Here’s the story in Andrew’s words:

I recently rented a D4, Wimberly head, and 600VR from you, and the day
before yesterday, I had a little bit of an accident. I was photographing a
coyote here in Yellowstone and I followed it into the woods about 300yds
away from the road. As I am taking pictures of the coyote, I heard twigs
breaking behind me, and as I turned around I saw it was a grizzly bear. I
picked up the tripod with the D4 and 600 on it and slowly started to back
away. The bear got closer and closer as I tried to back up. When the bear
got to within 20 yds. of me, I bumped into a brush pile that I could not
lift the tripod over, so I had no choice but to leave the gear and continue
away from the bear.

And here’s what happened next:

Courtesy Andrew Kane, moosephoto.smugmug.com

Courtesy Andrew Kane, moosephoto.smugmug.com

Not being willing to let things go with just a full pushover, the bear decided jumping up and down on the equipment would be a good idea too.

Courtesy Andrew Kane, moosephoto.smugmug.com

In a testament to the durability of the new D4, in Andrew’s words “The D4 functions properly, but the lensmount is bent and the images are backfocused severely”. In a testament to the wisdom of having the damage waiver, replacement equipment is already on it’s way to Andrew. If he gets shots like these with his backup equipment in a situation where I would simply be concentrating on not soiling myself, I can’t wait to see the shots he gets with the D4 and 600 VR in more stable conditions.

Addendum: Our friends Jody, Linda, and Anne sent us this “Bear’s Perspective Flow Chart” to present the bear’s point of view.

Bear's perspective flowchart, courtesy Anne Cavagnaro

Strictly speaking, decentering would involve one or more of the lens elements being off of the central axis of the lens. This would prevent the curved surfaces of the lens from bending the light properly. In severe cases it could result in halos or ghosting. In most cases it causes softness, especially away from the center of the lens. A decentered lens may be normally sharp in the center, but very soft in the corners. Or it may just be soft and blurry everywhere. Most lenses have one or more elements that are adjusted to correct centering. Which element that is varies depending on the lens type and design. The front element is often a centering element, with the rear element being the second most common centering element.

Diagram of a Perfect Lens

Lens with the Front Element Decentered

An element can also be tilted to one side or another. Strictly speaking this is not decentering, but it can have similar effects, so people often say a lens is decentered when in fact it’s tilted. In this case one axis may remain sharp, but the other will be out of sorts. If the tilt is side-to-side, the top and bottom of the image might be fine, but both sides soft. If it is corner-to-corner the top right and lower left corners might be fine, while the top left and lower right are soft. High quality lenses usually have one or more elements on which the tilt can be adjusted by two or three elliptical collars.

Lens with the Front Element Tilted

The third problem that can occur with lens elements is spacing. If elements aren’t the proper distance apart the lens may not focus the image sharply, or might not focus all the way to infinity. But the lens is not decentered and the tests we’re describing would be normal. There are usually a couple of elements that have ‘critical spacing’ within the lens. Theses are adjusted when the lens is assembled either by removable shims or by installing an element on a ‘ramp’ so that rotating the element moves it forward or backward.

Lens with a Poor Spacing of a Central Element

Some Generalizations

It would be nice if we could say “a decentered lens looks like this” and “a tilted lens causes that”. Unfortunately lenses are too complex for that. But one common issue people ask me about is a lens that seems OK in the center but is very soft in the corners. Sometimes that’s just how the lens is designed. But if the lens doesn’t have a reputation for soft corners, it may well be that the copy in question is decentered.

The Way It Used to Be

Back in the days of film and manual focus lenses, most repair shops had a centering collimator. It shined a star chart or a chart of concentric circles through the lens. If an element was decentered the chart would flare or be distorted in one direction. The technician would then adjust those elements that could be adjusted until the lens was properly centered. Obviously in film days you didn’t take a test shot, send it off to be developed, make an adjustment, take another shot . . . . it was all done off camera.

When lenses became more automated, so did testing: Lenses are mounted to the manufacturer’s electronic test system and most of the adjustments made electronically – or the computer report suggests which lens elements need be adjusted. The equipment is breathtakingly expensive and only the factory and some (not all) factory authorized centers have access to it. Standard centering collimators became a thing of the past, except for some specialty shops. (You can find them on eBay every so often if you want one to keep around the house.)

A Simple Test for Decentering

If you want to correct a decentered lens you need an optical bench, a computerized MTF program, or at the very least a lens projector and a lot of knowledge about which elements can be adjusted to correct an abnormality. But if you just want to check and see if your lens is centered properly (at least for most lenses) you don’t need much equipment at all. Now that we have live-view focusing and the ability to look at images in real-time, we nearly have the same thing as a centering collimator built into our camera and lens. You need just a couple of accessories: a tripod to give your camera a stable platform and a simple chart.

The screening test I’m going to describe is not perfect: a few lenses (particularly ultra-wide and 10x zooms) will give false-positive results; and this test won’t detect other causes of softness like problems with spacing of elements. But it’s at least 95% accurate for detecting decentering in our experience (which is for several thousand lenses tested over-and-over).

We use a the Zeiss modified Siemens Star Chart. Star Charts are often used as focusing aids, which is one of the reasons we put them on the resolution charts we use for Imatest and our other testing setups. You determine the lens is properly focused as the rays of the stars get closer and closer to the center. The Zeiss version adds a small white circle around a small black dot in the middle of the star chart. You can buy them for about $30.

Zeiss Siemens Star Chart

If you manually defocus the lens just a bit, the star rays and the white and black circles in the center blur, of course. If the lens is in proper alignment and pointed directly (lineup isn’t critical, you can eyeball it) at the star, the white and black circles remain circular as they blur. But if the lens is decentered or significantly tilted the center blur will ‘flare’ out in one direction or another as you defocus.

For example here are star charts shot just out of focus using four Canon 24-70mm f/2.8 L lenses at 70mm.

Even at the low resolution of blog-post graphics you should be able to tell that one of these things is not like the other: the lens in the lower left has a blur which is flared out toward 9 o’clock while the other three lenses have nice round blurs. The nice thing about this test is it’s not very set-up critical. The chart doesn’t have to be exactly in the center of the lens, you don’t have to line the lens up at exactly right angles to the chart, it doesn’t even matter which way you go out of focus (near or far) or exactly how far you go.

Let’s look at the resolution tests we did on the same 4 lenses using our Imatest lab – keeping the graphs in the same positions as the star patterns were above. Yellow areas are the highest resolution, blue are worst.

Imatest results for the 4 lenses

You probably notice that our lower left lens (the one with the flared star chart) has a pattern much softer on the right side. Also note the vertical axis (which shows the peak resolution) is different for this lens (the program automates the axis). The other three lenses peak near 800 line pairs, while the lower left lens peaks at about 600. It’s significantly worse than the other lenses.

Our star-chart flare did a nice job of identifying this decentered lens. The other thing that’s nice is the expensive Imatest lab shows me exactly how much the lens is affected, but it doesn’t show WHY it’s affected. The star chart made it pretty obvious the lens had a centering problem. We recentered the front element (the most common place for decentering on this particular lens) and the lens returned to perfect resolution.

If you don’t have $30 to spend on a Zeiss Star Chart, you can make a reasonable substitute yourself: just stick some white rings (like notebook paper reinforcing rings) on some black posterboard.

The flare isn’t as easy to spot as with the star chart, but it’s still noticeable. Here are the same four lenses that were used for the example above. Look particularly at the black center and see how it bleeds out onto the white circle at 5 o,clock — the opposite direction from the white flare noticed above. There is still some white flare noticeable: compare the outside of the white circle at the lower right and upper left areas. It’s not as easy to spot as the Star Chart flare, but it’s there (and this chart is free).

Uses and Limitations

Using the Star Chart as a poor-man’s centering collimator is a nice screening tool. It’s not perfect by any means. Some consumer grade zooms (particularly superzooms), some retrofocus lenses, and a few others show a pattern like this even when they are perfectly aligned, but those are the exception. For the majority of lenses, seeing a decentering pattern when the lens seems soft provides you some confirmation that the lens has a problem and may need a trip back to the factory. It can often answer the ‘is it me, or is it the lens?’ question. It may provide some further data when you’re trying to decide if the corners on your new lens are supposed to be sharper than they seem.

Because I know some people are going to ask, I don’t recommend trying to adjust lens elements at home using this method. Centering the lens element to remove the flare can be a good starting place and we do it here. But it’s just a starting place and you need a LOT of other equipment to fine tune the resolution (especially in a zoom). There are some lenses that don’t have any elements that allow tilt or centering — a factory rebuild is the only option when it gets out of sorts. With others, nearly complete disassembly is required to make such adjustments. And, of course, opening up your lens voids any warranty.

This is the second in a series of three posts about Imatest results on m4/3 mount lenses. The first post covered most of the lenses of 25mm and wider focal length. Most of the zoom lenses in that test were done at, or near, their widest focal length since we were concentrating on the wider angle lenses. This test run started by retesting most of the zoom lenses at 25mm, which we hoped would show a bit better performance since most zooms are weakest at their extremes.

We also did some confirmation testing at 25mm. First retesting the Panasonic – Leica 25mm f/1.4 because it just didn’t seem as great as we expected on the initial set of tests. Then we did some comparison testing, testing the same lenses on both the Panasonic GX1 and the Olympus OM-D E-M5. I won’t bore you with all the numbers, but testing 6 copies of the Panasonic-Leica f/1.4 didn’t change our initial results much. (The results have been updated on the previous article.)

I had assumed, since we test only unsharpened raw files, that camera brand would not make any difference, and it did not. We tested copies of the Panasonic 14mm f/2.5, the Olympus 9-18mm zoom, the Panasonic 7-14 f/4 zoom, and the Olympus 12-50 zoom on both cameras and there was no difference in MTF 50. This doesn’t mean there is not some distortion correction or other manipulation going on when using a same-brand lens on a given camera. It just means there’s no obvious manipulation of the raw image that affects MTF 50.

Testing the Zooms at 25mm

In the last article, we tested the Olympus 12-50 and 14-42mm f/3.5-5.6 II R lenses at 14mm.  I thought that focal length might be weak points for those lenses, so today we retested them at 25mm, more towards the center of their zoom range. We also tested the Olympus 12-50 f3.5-6.3 (we were out of stock during the wide angle test), Olympus 14-150 f/4-5.6, and Panasonic 14-140 f/4-5.8 OIS all at 25mm. Two or three copies of each lens were tested, and testing was done as described for the other article.

I’ll present the numbers in two tables:

In the first table, we’ll look at the MTF50 of each lens at the widest aperture it can use at 25mm

In the second table, we’ll look at the MTF50 with each lens at f/5.6

There are few comments to make about the zooms. Using the rule of thumb that a difference of less than 50 lp/ih is probably not noticeable, only the Olympus 14-42 lags a bit behind the others in resolution. The two superzooms, the Oly 14-150 and Panasonic 14-140 were both pleasant surprises. It’s quite a good showing they made, keeping up with the smaller-range zooms. Have to give some props to the Panasonic 14-45, too. It’s a low cost ($275) lens but hangs right there with the others. Finally, the zooms haven’t changed much between their wide end in the previous tests and the middle of their range we tested now.

Testing the 45mm Primes

We have two 45mm lens choices for m4/3: the Panasonic-Leica 45mm f/2.8 and the Olympus 45mm f/1.8. There are a lot of differences in the two. The Olympus gives a wider aperture, is smaller, and $250 cheaper. The Panasonic-Leica has built in Image Stabilization. I’ve presented this table a little differently so you can compare the two lenses at equal aperture.

In our tests the Panasonic-Leica 45mm does outresolve the Olympus by what is probably a noticeable margin if you compared them side-by-side. Results from both are excellent, though, and I can’t imagine anyone being disappointed with either one.

Oh, and One More Thing

I was just about to break down the testing set up when the receiving people brought me a present: several copies of the Sigma 30mm f/2.8 and 19mm f/2.8 in m4/3 mount. These were spectacular on the NEX system so I had to go ahead and run the tests on these before they went out on rental.

Several things are interesting here. First, the Sigma lenses give excellent resolution on m4/3 mount like they do in NEX mount. No surprise there. Second I would have expected the resolution to be lower on m4/3 mount since we are measuring in line pairs / image height and the NEX-7 has 4000 pixels of image height versus the m4/3 3460 pixels and Imatest measure system (camera and lens) resolution, not just the lens.

As expected, the Sigma 30mm has slightly lower resolution on m4/3 cameras. However, the Sigma 19mm was had nearly the same resolution in m4/3 mount as it did in NEX mount. In m4/3 mount, therefore, the Sigma 19mm and 30mm were had about equal MTF50 (the 19 actually a tiny bit sharper in the edges and corners at f/2.8). (In NEX mount the 30mm was slightly sharper than the 19mm.)

I’m not sure why the difference, so what follows is purely speculation and I welcome other people’s ideas. In looking at our m4/3 results overall, it seems there is a tendency for wider focal lengths to resolve at least as well as longer focal lengths. In most systems we’ve tested that hasn’t held true: wider lenses, with a few notable exceptions, tend to be a bit weaker. Perhaps the m4/3 sensor format makes designing wider lenses easier or more effective. Perhaps the m4/3 sensors, particularly the newest 16-megapixel sensors have a better or more effective microlens array? Perhaps there is some sharpening or contrast boost going on in-camera to the raw images? Note: Please read Thom Hogan’s excellent comment below: it makes more sense than any of my ideas did. 

It’s also possible there is some defect in our testing set up that’s giving an advantage to wider focal lengths on m4/3 cameras. I don’t think this is likely, we’ve run 5,000 lenses through our Imatest lab and I think we’ve worked the kinks out. But it’s always possible. I’ll look forward to seeing the results from other testing labs to see how theirs compare.

Part 2 Summary

Having been through most of the m4/3 lenses now I think there are some very obvious conclusions: 1) there are a lot of good prime lenses available for m4/3 from 14mm to 45mm. It’s interesting that the new Sigma lenses stand out as superb compared to other NEX lenses, but are just another good prime lens on the m/4/3 system.

Things are a bit different on the zoom side. There are some good consumer quality zooms, but other than the Panasonic 7-14 f/4, there are not any that I would consider ‘top’ or ‘pro’ quality zooms. Several of the zooms have good resolution, but they are all aperture-impaired. I think this is a big hole that needs to be filled, especially now that we’re getting reasonably fast autofocus in mirrorless bodies. An f/2.8 range 35-100mm would kick some serious butt, even at a premium price. Even a reasonably long wide-aperture prime, something like an 80mm or 100mm f/2.8 would be welcome.

The biggest gap in the m4/3 lens lineup, though, is certainly going to be at the long end and we’ll cover that in the third part of this series. I’d love to find an exception, but having spent a weekend shooting every one of the m4/3 mount long zooms and comparing them to what’s available for SLRs, I don’t expect a lot of good results.

Roger Cicala

Lensrentals.com

May 2012

Addendum: Wouldn’t you know, the day after I wrote my little diatribe about needing good quality f/2.8 zooms for m4/3 the first preliminary reviews of the Panasonic 12-35 f/2.8 OIS come out and are very positive. Now, just give me that good telephoto, guys, and I can stop juggling mirrorless systems

Long ago in a lifetime far away, I discovered photography. I loved it. I mean, I really, really loved it. Not just learning how to make photographs. I loved learning how the camera and lenses made those photographs. I loved learning about the major and minor differences various lenses had. I spent every free moment using equipment and learning about our craft. I spent almost every free dollar buying more equipment.

In a burst of insanity I decided the best thing a gearhead photographer like me could do was to start a photography rental company. I’d have to buy everything because now it would be ‘stock’ and ‘assets’. Brilliant!! Like people say, it’s not work when you’re doing what you love. (I will mention, for those considering a similar path, that when you are working 14 hours weekdays, 8 hours Saturday and Sunday, and losing money, you should not mention how much fun it is to your wife.)

Lensrentals was more successful than I’d ever dreamed it could be.  What I found out, though, was that I wasn’t running my personal photography toy store.  I was leasing office space, negotiating shipping rates, filling out two gazillion governmental forms, learning how to regain stolen equipment, obtaining lines of credit, hiring people, managing employee benefits, trying to figure out what would rent well, and various other things that did not fit my definition of really fun stuff. Not to mention trying to learn about those business –type things like return-on-investment, depreciation, profitability, market share, corporate tax structure, and a bunch of other terms I still can’t understand.  (Maybe unwilling to understand is more accurate, but whatever.)

The bigger the business got, the less time I spent with the equipment I loved and the more time I spent being a businessman. I learned several things in a fairly short time: 1) I’m not a good businessman, 2) I don’t want to become a good businessman, and 3) I want to play with the toys and lots of business responsibility keeps you from playing with the toys. For those of you thinking I should add “I refuse to grow up” to that list, I had figured that out way before Lensrentals started.

During the last several years Drew, Tyler, and Kristin, who actually have business sense and training, have taken over the day-to-day operation of Lensrentals. They not only do it a lot better than I did, they like doing all that stuff I hate to do. Even stranger, they’ve never expressed the slightest interest in taking lenses apart. Go figure. They all came here when the company was still small, leaving secure corporate jobs and taking significant risks (and pay cuts) to do so. They’ve had as much to do with the growth and success of Lensrentals as I have.

So it makes sense, and is with real enthusiasm, that I’ve accepted an offer from the current management team to buy a majority interest in Lensrentals. I will remain owner of a significant portion of the company’s stock, but am now “one of the owners” not “the owner”.  I’m totally comfortable that the company I started will continue to be run the way I wanted it run, because the people buying it are the ones who’ve been running it that way for several years.

The best part is they basically told me “you can do whatever you want to do as long as you remain an active part of Lensrentals.” So going forward, I will continue to head our quality assurance, repair, and research efforts. In other words I will spend my days taking stuff apart, figuring out how it works, testing it, repairing it, and writing about it. I’m in gearhead heaven once again.

What will you notice that’s different? Nothing. The only thing changing is that I’ll have more time to do the stuff that leads to most of these blog posts.

Roger Cicala

Lensrentals.com

Every once in a while, though, I’ll evaluate a piece of equipment as a possible rental item and really be impressed with it. Impressed enough to write something about it even though we don’t even stock it for rent (yet). That happened today. We received a Nanoha Ultra Macro lens for mirrorless cameras that I’d ordered to evaluate as a possible rental item. Let me start by saying my expectations were low. The lens is made from a microscope objective so it has a maximum f/11 aperture. It has some LED lights on the front which I usually think of as something cheap and ineffective. If you Google Nanoha you get 42 pages about a female Anime character. But they had some nice images on their site, and I thought it might, might be worth a look.

I was a bit more impressed when I opened it up: the LED lights are powered by a small self-contained unit with two AA batteries, and the LEDs were really pretty bright. Everything was well built and the instructions were clear. The focusing and aperture rings were smooth and solid. It comes with 5 little holders to put stuff in at just the right distance in front of the lens to focus on it (shooting range is a rather close 8 to 11 millimiters), which I thought was a nice touch.

Nanoha 5X mounted to an NEX 7

You can shoot without the holders (which we did). A nice tripod with a focusing rail is not a must, but it’s near to a must. So it’s a really limited, one-trick pony lens that shoots things at 4x to 5x Macro. Like, say, the Canon MP-E 65 5x Macro lens. Not something most people would use everyday, but really just an absolute blast to play with. How much of a blast? Enough that the entire inspection department got yelled at and told to get back to work after I led them on a scavenger hunt for more little stuff we could take pictures of. All work ceased for an hour while 7 of us were fighting over who got to play with it next.

Since we had such a good time with it, I thought I’d share some of the images Tim made with it. I’ll post a Nanaho Macro shot, followed by a standard shot of the same object. See if you know what the Macro showed before looking at the item in a standard image.

Ribbon cable with chips and fuses

Microfiber lens cloth

Piece of packing foam

Toothbrush

leaf

And a few more images that I didn’t have regular shots of. In two of the three cases because we ate or drank the photographic subject before we could do regular shots. In the third case, well, he (or she) escaped.

First, some freshly ground coffee.

Ground coffee (Brazillian Monte Carmelo for those who are into it as much as we are).

A piece of bread (whole wheat, I believe)

And what would a Macro post be without the obligatory spider? I mean it’s the macro lens equivalent of the pet dog shot we all take with a new portrait lens, right?

Obviously we like this little lens. There was a fight over who got to take it home tonight, and there’s another brewing over who gets it for the weekend. We’ve ordered a couple of copies for rental items, but if you’re a m4/3 or NEX shooter who’s into this kind of thing I’d buy one. At $480 it’s reasonably priced, especially when you consider it comes with a built in light.

Remember, though, the working distance is 8 to 11 MILLIMITERS. You’ll either want to take pictures of things  you can put in the little plastic holder, or you’ll want some macro photography aids like a focusing rail and things to hold your subjects in position. But if you’ve always thought “I wish there was a microcsope type macro lens for 4/3 or NEX format, well, now there is.

Roger Cicala

Lensrentals

May 2012

A lot of Sony users liked seeing some Imatest results for NEX lenses, and some micro 4/3 users asked us to do the same thing. That’s a more complicated undertaking for several reasons. First, there is a much wider selection of native lenses for micro 4/3. Second because there are a lot of different micro 4/3 cameras. But we wanted to tackle the project because, quite honestly, we’d never done any lab testing on m4/3 lenses. We wanted to know, too.

Making the project something we could do in reasonable time means cutting some corners. First we can’t test every camera. We chose the Olympus OM-D EM-5 for several reasons. We wanted a camera with 16-megapixel resolution, which eliminated most m4/3 cameras. Also, the physical layout of the Olympus lets us test more quickly in our lab than we can with any of the 16-mPix Panasonic cameras. There just wasn’t enough time in one day (all we could set aside for this right now) to do two different cameras.

Second, we split the test into two sets of lenses because there were so many to test. In this part we did lenses that were 25mm or wider in focal length. We’ll do the longer lenses later. Zooms with a long range were tested near their wide end in this test, and will be tested again at longer focal lengths when we do the longer lenses.

Disclaimer

The usual “don’t read this stuff and go insane” cautions apply: this is a test of lens and sensor resolution for MTF 50 (detail resolution) done at a distance of 10 to 30 feet, depending on focal length. The results might be different at 4 feet or 400 feet. The results might be difference if we tested at MTF 10 for best acutance. Focus is done manually and bracketed so it’s not a test of a camera’s autofocus ability. The tests use a controlled-lighting test-target with a hardware mounted camera at ISO 400, so photos taken in the dark of night or hand-held for 12 second exposures will give slightly different results. It doesn’t measure autofocus speed, lens size, manual focus feel, bokeh, color rendition or anything like that. It’s not a lens review; it’s one simple test of resolution.

More importantly, remember that while we are testing RAW files, both Olympus and Panasonic seem to do some in-camera corrections on their own lenses, but not the other brands. We don’t know what effects, if any, that might have on this test. Possibly Panasonic lenses might do a little better on Panasonic cameras and Olympus lenses a little worse. We’ll figure that out later, but I doubt any such corrections will affect the MTF 50 at all. If it did the effects should be minor and limited to the edges and corners. But we don’t know for sure. Yet.

Addendum 4/13/12: I had hoped that the m4/3 community might not be quite as Fanboy riddled as Canon and Nikon. Obviously I was wrong about that. Because there was such an uproar about the results of the Panasonic / Leica 25mm I’ve repeated the tests on 6 copies (all that we have) and also on Panasonic cameras, because Fanboys have been on suicide watch and full-attack-mode since they’ve taken them so out-of-context. The average of 6 lenses on both Olympus and Panasonic 16 Mpix cameras are now reported. The results are basically unchanged.

The Lenses

We had a nice selection of wide-angle m4/3 lenses in stock on the day we conducted these tests:

• Voigtlander 17.5mm 0.95 Nokton and 25mm f/0.95 Nokton
• The Pancake lenses: the Panasonic 14mm f/2.5, Olympus 17mm f/2.8, and Panasonic 20mm f/1.7
• Other primes: the Olympus 12mm f/2.0 and Panasonic/Leica 25mm f/1.4 ASPH
• And a few zooms: the Panasonic 7-14 f/4, Olympus 9-18 f/4-5.6, Olympus 14-42 f/3.5-4.6 II R, and the Olympus 12-50 f/3.5-6.3 EZ

Imatest Results

The values are for MTF-50 (which correlates with fine detail resolution) measured in line pairs / image height. The first (higher) number is the MTF 50 measured at the center of the lens only. The second (lower) number is the average of the MTF-50 measured at 13 points including the center, 4 corners, 4 sides, and 4 mid points. I keep a point total for every time someone posts the question “what do the two numbers mean” as an indicator of the reading comprehension for each group of camera users. I have high expectations for m4/3 users, so please don’t let me down.

I’ll also mention that numbers sometimes make minor differences seem really large. A difference less than 50 lp/ih is probably not noticeable in real-world photography. So if you print a reasonably sized image from a lens resolving 860/750 lp/ih and compared it to a shot with another resolving 810/700 lp/ih the difference would probably not be noticeable. You would almost certainly notice a difference of 100 lp/ih.

At Widest Aperture

The first graph shows the numbers for each of our lenses (zooms measured at 30mm) with the lens aperture wide open. This test isn’t a level playing field, since some lenses are f/4 wide open while the primes are at anything from f/1.4 to f/3.5. But since some people tend to shoot every lens wide open, it may be useful to know how well (or not) the lenses do at their widest aperture. I’ve listed them from widest to longest focal length. The zooms were all shot at 14mm so they might be a bit better or worse at other focal lengths.

MTF 50 at Widest Aperture

*Panasonic-Leica results on this test are the average of 6 copies. The average numbers are slightly better at f/1.4 than  the first version of this article, which reported only one copy, but the difference is not really significant.

There’s not a lot to see from this set of numbers. As usual, good primes are as sharp, or sharper, at wide apertures than consumer-grade zooms are at lower apertures. The Panasonic pancake lenses pleasantly surprised me. Pancakes are usually not the greatest lenses, but he Panasonic 14mm and 20mm are really quite good.

Stopped Down to f/2.8 or Smaller

We can level the playing field a little bit by shooting the wide primes at f/2.8, as shown in the graph below. It’s somewhat more meaningful: the zooms are still at smaller apertures, but everything else is shot at f/2.8 here.

MTF 50 at f/2.8

*Panasonic-Leica results on this test are the average of 6 copies. The average numbers at f/2.8 are slightly better than  the first version of this article, which reported only one copy, but the difference is not really significant.

By f/2.8 the superiority of most of the primes over most of the zooms becomes pretty apparent. The Olympus 17mm f/2.8 is easily the weakest of the prime lenses, which isn’t really surprising. It’s an older design and a consumer-grade pancake lens. The two Panasonic pancakes being so good surprised me, though. They’re not much more expensive than the Olympus 17mm. I had expected a bit more out of the Panasonic Leica 25mm given it’s cost and build quality. It has other good qualities, this is simply the results for MTF 50. The Voigtlander lenses, despite being built for ultra-wide aperture (which usually results in a rather soft lens) did quite well. But as easily the most expensive lenses in the group, that seems appropriate.

Personally my biggest disappointment was in the Panasonic 7-14 f/4 zoom, which is probably my favorite m4/3 lens. But we were testing at 14mm, and that lens is actually a bit better at the wide end. And really, it’s probably a bit much to ask a lens to be this incredibly wide, and also incredibly sharp. The Nikon 14-24 pulls it off for about $2,000, but that’s the only one I can think of.

MTF 50 at f/4

We can level things out even further by shooting all of the lenses at f/4. Most of these lenses would get a bit sharper still at f/5.6, especially in the average (as opposed to center) resolution.

MTF 50 at f/4

*Panasonic-Leica results on this test are the average of 6 copies. The average numbers at f/4 are slightly lower than  the first version of this article, which reported only one copy, but the difference is not really significant.

There’s really not much new information here that we didn’t already see at f/2.8. The Olympus 9-18 and 12-50 zooms are clearly better than the little 14-42 zoom. The Panasonic 7-14, despite working at such wide angles, is better than either of the others. Overall another “you get what you pay for” situation – slapping  II on the name doesn’t make it a great lens. (BTW – although I expect m4/3 shooters to go a little less Fanboy than the Canon and Nikon guys, let’s get this out of the way: some Fanboy always says “the rental guy wants you to rent the most expensive lens”.  Actually the rental guy could care less: the profit margin is the same on a really expensive lens and a cheap one.)

Of the prime lenses, only the Oly 17 pancake isn’t very good; the Panasonic pancakes were clearly better. The Panasonic/Leica 25mm disappointed a bit: it was good but I had expected it to be THE best of the bunch and it’s not. I only had one copy the day of this test, though, so I would take this result with a grain of salt until I can repeat it with other copies. There’s a chance it was just a copy variation thing.  The Olympus 12mm was just excellent, though, and the Voigtlanders provide an amazing wide aperture lens.

Part 1 Summary

Compared to the NEX system lenses I just tested, m4/3 users have a host of wide-angle, native-mount choices. There are good pancakes, standard primes, interesting (and expensive) ultra-wide aperture primes, all at reasonable prices. There’s a good f/4 ultrawide zoom and a couple of reasonably sharp zoom lenses. The big hole, as I see it, is that there’s no wide-aperture zoom, period. For my shooting style, the m4/3 begs for a wide aperture.

Remember, we’re just talking about resolution here. When I’m choosing a lens, it’s my starting point: I require good resolution. But that’s all it is, a starting point. If you’re seriously considering some of these lenses, go to a good review site where you can get more in-depth information about distortion, handling, focusing accuracy, etc.

In this part we’ve looked at most, but not all, of the m4/3 lens choices for shooting at 25mm or wider. We’ve only tested on the Olympus OM-D. We’ll do some testing on at least one of the Panasonic 16mm cameras just to make certain there’s no significant difference soon (I doubt there will be, but it’s possible). We’ll also do a second post on the longer lenses in the next couple of weeks.

Roger Cicala

Lensrentals.com

May 2012

As always, it is our goal to be the best rental company in the business. As part of that, we want to have the easiest to use and all-around best website of any rental company. So, over the past two years since our last iteration of our site went live, we’ve gathered feedback from all of our customers about what they liked and what they didn’t like about our site. For the past six months, we’ve put a lot of work in redesigning our site from the ground up, to fix the things that people don’t like, and to make the well received features of our site even better.

Navigation

We’ve gotten a lot of feedback that the top-button navigation system on the old version of the site was confusing or difficult to navigate. We’ve moved the navigation from the top to the left side of the screen. To navigate, simply select your camera system, and then proceed through the categories as you did on our old site.

At any point, should you want to choose a different camera system to navigate to, simply click the name of the current camera system to be presented with the list of all camera systems.

Filtering & Sorting

Another common point of feedback we’ve received is that, because we now carry so many products, it can be difficult to narrow down your selection to just a few products. To improve upon this, we’ve added filtering options. Our filters will work whether you’ve accessed a list of products through our regular navigation, or if you’ve used the search function of our site.

At this time, the filtering categories are mostly lens-specific such as focal length, maximum aperture, and active stabilization. We hope to expand the filtering choices to other product options in the future.

We’ve also added the ability to sort a list of products by different attributes such as weekly price, popularity, newness, or focal length.

Product Pages

We know how much everyone loves the large amount of information we try and give you on each product, whether it is Roger’s Take, MTF charts, or detailed specifications. We also know how much everyone hates how long and disorganized all this information has made some of our pages. That’s why we’ve added tabs to our pages, allowing you easy access to all the information available, if you need it, without cluttering up the page if you don’t.

Shipping

Along with the new site, we’ve changed our default shipping carrier to FedEx, as well as changed our shipping speeds on some orders. Rest assured, whether our site tells you your order is going to ship via Next Day Air, 2nd Day Air, 3rd Day Select or Ground, your order is guaranteed to arrive on the date you selected, just like before.

Since we know some of you prefer UPS, UPS shipping will always be available, for a slight extra charge (it costs us a bit more to ship UPS, so we have to charge a bit more). Simply change your shipping method using the drop-down menu during checkout.

As always, we have support available via phone, email and chat during business hours (8:00 AM – 5:00 PM CT), and email support available after-hours and on the weekend if you run into any problems with our new site, or simply can’t find what you are looking for. Contact us at any time!

Let me say it here first: I knew this was going to be the fix since the first time I took one apart: Canon has this very cool black tape they used to cover circuit boards (I’m assuming either water resistance or electrical shielding or both) and I figured they’d just slap another piece over (or under, depending on your point of view) the top LCD light. Which is exactly what they did. Yes, I’m making fun, but it’s a perfectly good solution and it works flawlessly.

And because I know you have enquiring minds: I did power the camera up with the shell off in a dark room. There is no more leak.

Addendum: for those who notice there is a black plastic piece over the shutter button that was removed in the first photo, but not this one.

Read This Please!!!

Sometimes I forget that other people don’t spend most of their days looking in cameras and lenses. Some people seem to think tape is bad or cheap fix. It’s not. Actually, I can’t think of any SLR camera that doesn’t have a bunch of tape inside. Nor can I remember any high quality zoom lens that doesn’t have tape inside (some of the cheaper consumer grade lenses don’t). This stuff lasts for the life of the camera and then some. Trust me, I’ve taken some water soaked equipment apart where the only thing still working was the tape.

In a previous post, I praised the broad sheets of the same tape used to cover all of the circuit boards: it obviously provides added protection. This solution seems silly, but it’s logical and effective.

Roger Cicala

But some of us (myself included) like to shoot native-mount lenses, or can’t afford the price of Leica glass to put in front of the camera. The NEX-7 is physically set up in a way that allows us to mount it to our Imatest set up, and we happened to have most of the new lenses in stock one day, so I thought I’d take advantage of the situation to do some resolution testing. (Because I know someone will ask, we can’t test many of the small cameras because mounting to our tripod system blocks the memory card door. It takes 10 to 20 test shots to align the test setup. But if you have to unmount from the tripod mount, you have to start over. So it’s not possible for us to test some camera systems.)

The usual “don’t read this stuff and go insane” cautions apply: this is a test of lens and sensor resolution done at a distance of 10 to 30 feet, depending on focal length. The results might be different at 4 feet or 400 feet. Focus is done manually and bracketed so it’s not a test of a camera’s autofocus ability. The tests use a controlled-lighting test-target with a hardware mounted camera and Imatest software at ISO 400, so photos taken in the dark of night or hand-held for 12 second exposures will give slightly different results. It doesn’t measure autofocus speed, lens size, manual focus feel, bokeh, color rendition or anything like that.

The Lenses

Still the results are interesting and I suspect none of you would pick one of the eventual resolution co-champions out of the lenses we tested:

Leica 50mm f/1.4 Summilux on a Fotodiox adapter (picked because it’s the highest resolution 50mm lens we’ve tested on other bodies).

Sony 18-55mm and 18-200mm E-mounts zooms both tested at 30mm because that was our original point of interest. That was probably the sweet spot for the 18-55, but may have handicapped the 18-200 a bit: it seems better around 50-90mm. But certainly it’s better at 30mm than at the long end.

Sony 16mm f/2.8; 24mm f/1.8; 30mm f/3.5 Macro and 50mm f/1.8 E mount prime lenses.

Sigma 19mm f/2.8 and 30mm f/2.8 E mount lenses.

Unfortunately we did not have a 55-210 Sony zoom in stock at the time of the tests.

Imatest Results

The values are for MTF-50 (which correlates with fine detail resolution) measured in line pairs / image height. The first (higher) number is the MTF 50 measured at the center of the lens only. The second (lower) number is the average of the MTF-50 measured at 13 points including the center, 4 corners, 4 sides, and 4 mid points.

The first graph shows the numbers for each of our lenses (zooms measured at 30mm) with the lens wide open. This test isn’t a level playing field, since some lenses are f/4 wide open (the zooms) while the primes are at anything from f/1.4 to f/3.5. But since some people tend to shoot every lens wide open, it may be useful to them. Please note: On Monday, May 7th I retested a number of Sony-Zeiss 24mm f/1.8 lenses because the initial two we tested seemed strange, and were very close in SN (it’s all we had in stock at the time). I’ve since repeated that test with different copies and the new results at f/1.8 are much better. I’ve changed the results below to reflect the better results — here’s a good example of tests of one copy of a lens, even two copies, is never enough to base your decision on. We’ve examined the copies from the original test carefully and other than the softness at f/1.8 (which is gone by f/2.2) we still haven’t figured out what problem they have.

MTF 50 at Widest Aperture

We can level the playing field a little bit by shooting the wide primes at f/2.8. That gives us the numbers below. It’s somewhat more meaningful: the zooms are still f/4 and the Sony 30mm Macro at f/3.5, but everything else is shot at f/2.8 here. Notice the results for the little, reasonably priced Sigma 30mm f/2.8 are in bold. While some lenses are close to as sharp in the center, nothing is nearly as good in the corners. Impressive.

MTF 50 at f/2.8

We can level things out a bit more by shooting all of the lenses at f/4. Most of the lenses would get a bit sharper still at f/5.6, especially in the average number. Notice the Sony 24mm f/1.8 has gone from easily the worst resolution to among the best (at least in the center) by stopping down a bit. It really was much, much better at f/2.0 so I would consider that the real maximum aperture for that lens. (We checked a second copy and it was exactly the same – it’s possible that we had two copies that were bad at f/1.8 and not at f/2.0, but I really, really doubt it. I’ll check a couple of others when they get back from rental to be certain.) Really only the Sony 50mm and the zooms are lagging behind in the center, and the Sony 16mm pancake does, of course, still suck.

MTF 50 at f/4

Comparing Lenses

Imatest is measuring the resolution of the lens-camera combination (as opposed to an optical bench, which measures the lens’ maximum using collimated laser or LED lighting). We chose the Leica 50mm f/1.4 Summilux because we’ve tested it on a lot of other camera systems and know the lens is as good as it gets from a resolution standpoint. That the Sigma 30mm, a $200 lens, is keeping pace with it is really amazing. Obviously it’s not really a wide aperture prime, with a maximum aperture of f/2.8, but it gives world-class resolution. The Sony 24mm f/1.8 is not the bargain the Sigma is, but from f/2.2 on it has amazing center resolution, although it lags behind the other two in the corners. The Sony 50mm f/1.8 appears to be tuned like the Nikon 50mm f/1.4 G: it’s not quite as sharp in the center, but keeps good resolution across the entire front of the lens. Notice it’s average resolution is up there with the 3 best lenes, although the center isn’t quite as sharp as the other primes.

The Sony 30mm Macro may be better at Macro distances (should be actually), but the Imatest setup requires us testing it at about 15 feet distance. Very decent also describes the Sigma 19mm f/2.8 which is clearly far better than Sony’s 16mm pancake. The zooms, well, they’re about what we thought: OK lenses for when you need a zoom.

Comparing Systems

It’s always a little complex to compare Imatest resolution between cameras with different sensor sizes, since the numbers we generate are measured in line pairs / image height, and image height differs.  I hesitated to do it at all, because it will inevitably lead to 716 posts about whether it’s most appropriate to multiply the resolution of the crop sensor of divide the resolution of the full frame, and by what amount. But my thought is to keep it simple. If I take a picture of a building with whatever camera I’m shooting so that it is the same size on the image I print, then image height of the sensor doesn’t matter.

In other words the printer doesn’t care what size the sensor that took the picture was if the pictures were the same. Given this ‘Roger Rule’ the results with the NEX – 7 and good lenses are about what we’d expect: resolution at f/4 with a good lens is about what we see with a Canon 5DII or III (1050 / 800 or so LP/IH) with a good lens, not quite as good as a Nikon D800 (1200 / 1000 LP / IH). So shooting with one of the better lenses  listed above you can certainly get all the resolution you should ever need.

If you want to shoot a zoom, though, things aren’t so pretty. For example, a Nikon 24-70 f/2.8 shot at f/2.8 gives around 890/830 jumping up to 940 / 875 at f/4. A Canon 70-200 f/4 resolves at 920 / 845 at f/4. The Sony zooms are both about 855 / 660, which means the corners of a good Canon or Nikon zoom are about as sharp as the center on the Sony E zooms. Those are more expensive zooms, no question. I’m not trying to compare apples and oranges. Simply stating that the NEX system doesn’t offer a high quality zoom and giving some examples of what a high-quality zoom’s numbers would be like.

But for prime lenses, at least, we’re now getting some good quality, native mount lenses to put on NEX cameras without an adapter. My hat is off to Sigma for making a couple of really good lenses at amazingly good prices. Well done! Hopefully as the user base of E mount cameras increases we’ll start to see more third party options.

Roger Cicala

Lensrentals.com

April 2012

]]> http://www.lensrentals.com/blog/2012/04/nex-7-lens-imatest-resolution-comparison/feed 25 http://www.lensrentals.com/blog/2012/04/quick-tamron-24-70-mtf-data http://www.lensrentals.com/blog/2012/04/quick-tamron-24-70-mtf-data#comments Fri, 27 Apr 2012 20:06:19 +0000 Roger Cicala http://www.lensrentals.com/blog/?p=6583 We got a couple of Tamron 24-70 f/2.8 VC in Canon mount today and I was able to compare them, very briefly, with the Canon 24-70 f/2.8 L.

The Tamron is not quite the range of the Canon on the long end, clearly a few mm shorter than Canon (which is clearly a couple of mm short of 70mm). For anyone who doesn’t know, manufacturers “round” up or down to give the numbers they actually put on the zoom. I can’t see where being a bit shorter is going to affect anyone very much.

Autofocus is reasonably fast, although the Canon may be a bit quicker. Nothing dramatic like the Tamron 70-300 (which was horribly slow), though. Again, I can’t see this making a ton of difference to anyone.

Imatest results were clearly in favor of the Tamron, though, at both the long and short ends. I was able to run 3 copies of the Tamron on 2 cameras and results were as consistent as we’d like them to be.

These are MTF 50 results (3 copies of each lens tested, best results of each copy averaged, variation +/- 2.5%) measured in line pairs / Image height on 5D Mk II test cameras from unsharpened raw files.  Ctr = the Center Point, Avg =  a weighted average at 13 points on the lens (center, 4 mid 1/3, 4 corners, top and bottom) The Tamron is clearly better on the wide end, particularly in the average number across the entire lens. At 70mm the centers are about the same (you couldn’t see that difference, even in reasonably sized prints), but the average across the lens is again better with the Tammie

The Lens sharpens up even further at f/4, and a bit more, particularly in the corners at f/5.6 as shown in the graph below.

MTF 50 improves to f/4 in the center and f/5.6 in the corners.

So what does this all mean? It means the lens has potential to be good. We’ll have to wait until some real world results and reputable reviews come in to get some real-world initial impressions.