On May 7th, our customer service manager, Sharon Perez, passed away unexpectedly. Sharon was a wonderful friend and co-worker for the past 4 1/2 years. She was an integral part of our Lensrentals family and she will be sorely missed by all of us.
Out of respect for our friend Sharon, and to allow her co-workers to attend her memorial service, our customer service department will be closing at 12:00 PM CT today. If you need our assistance, please call us before this time. We will have staff monitoring email throughout the afternoon but our response times will be slower than normal.
I want to give credit to Canon for so quickly handling the problem we first reported with some T6 sensors. We announced the problem on April 30th, and within 10 days Canon had determined which cameras were affected (those with Serial Numbers beginning with "01 or "02") and issued a product alert.
Let me add that most cameras in the affected SN range do NOT have the problem. Some cameras have a mark in the battery door that identifies them as not possibly affected.
Credit for image, Canon, USA. http://www.usa.canon.com/cusa/support/consumer?pageKeyCode=prdAdvDetail&docId=0901e02480f0bcb2
Even if your camera does NOT have this mark, it still probably isn't affected. If you lock up the mirror for sensor cleaning you can look and see if you have one of 'those' sensors. If you aren't sure, Canon will check for you at no cost and correct the problem without charge, although it will take them a bit of time to get a solution ramped up.
Some Information and Speculation
The following is NOT information directly from Canon, but I think it's quite reliable. Several knowledgable people have told me the issue arises from the coating (more properly sputtering) process on one of the pieces of glass making up the sensor stack. If you want more detail on it, Dave Etchells at Imaging Resource has as a complete discussion of it.
The takeaway message is the sensor issue is not going to occur to a normal sensor over time. If you camera is fine now, it will be fine in several years. The problem probably occurred at a supplier to Canon and the QA process just missed it.
And Some Proper Credit
I can't say enough about how impressed I am with the speed with which Canon has addressed the issue. We've seen problems like this ignored for months, or denied until the next version of the camera is released. Mistakes in manufacturing complex devices are inevitable. How the manufacturer handles them is the variable.
If, like me, you'd like to see more manufacturers take positive action, and fewer blow smoke up our rears for months or years, the please join me in supporting Canon for doing exactly what we would hoped they would do.
We got a pre-release set of Sony FE 90mm f/2.8 G OSS Macro lenses in for preliminary testing last week, and I was kind of excited about this lens for a couple of reasons. First it simply gives me a nice short telephoto prime option that has been lacking in the lineup (although the Zeiss 85mm Batis lens will be coming along fairly soon). Second, it gives me a true macro lens at the focal length I prefer.
Image Courtesy Sony, USA
I hoped that the combination of a good macro lens with the A7r sensor would turn out to be a winner. We used our Imatest lab to compare Sony 90mm f/2.8 G OSS lenses mounted to Sony A7r cameras, and compared them with Canon 100mm f/2.8 IS Macro lenses shot on Canon 5DIII cameras in our Imatest lab. (For those who are curious, we can't test Sony E mount lenses on an optical bench because the electromagnetic focus system requires electrical power to operate. Until we do some really geeky, overly complex engineering modifications, the optical bench isn't an option for Sony E mount lenses.) It would have been nice to also compare with a Nikon D810 and Nikon 105 f/2.8 Micro lens, I know, but our time is limited.
Overview of the 90mm f/2.8 G OSS
First of all, if you're used to Sony E mount lenses being smaller than their SLR counterparts, you'll need to get over that. The 90mm lens is very similar in size to the Canon 100mm f/2.8 IS and other SLR macro lenses in this focal range.
Canon 100mm f/2.8 IS on 5D III (left) and Sony 90mm f/2.8 on A7r (right). Lens rentals.com, 2015
If you'd like the numbers for comparison, I've put them in a table.
Sony 90mm f/2.8 OSS
Canon 100mm f/2.8 IS L
Nikon 105mm f/2.8 Micro VR
Filter size (mm)
Min. Focus Dist. (in.)
The Sony is a bit more expensive, but that's not unusual for a new release. Otherwise they are pretty similar in specifications.
We tested these in our Imatest lab but at two different focusing distances and with two different charts. Remember, the higher resolution of the A7r camera will make the system resolution higher. My thinking when making this comparison was if the Sony lens wasn't up to the standards of the Canon (which is arguably the best macro lens in this focus range), then the Canon system would be close to the Sony, despite the higher resolution of the Sony camera.
Our first test was using a standard Imatest setup shot at a distance of about 20 feet.
Canon 100mm f/2.8 IS L
Sony 90mm f/2.8 G OSS
4 Corner avg.
We then repeated the tests, using a high-resolution, back lit chart made by Imatest specifically for testing macro lenses. The focusing distance was now just under 2 feet. This doesn't give us quite full 1:1 macro working distance, but it's pretty close.
Canon 100mm f/2.8 IS L
Sony 90mm f/2.8 G OSS
4 Corner avg.
At both focusing distances the Sony system is clearly out resolving the Canon system. We would expect that, to some degree, given the higher resolution Sony sensor. But the difference was, quite frankly, surprising to me. It would seem to indicate the new Sony 90mm Macro lens performs at least as well as the Canon 100mm f/2.8 IS L, from a resolution standpoint, anyway.
Please don't take this out of context. These are simply Imatest MTF50 numbers. By that standard the new Sony 90mm f/2.8 G OSS Macro seems to be a superb addition to the E mount lineup, and the lens on an A7r should provide superb resolution. We'll have to look at more in-depth, hands on reviews to see how it actually performs in the field, what the bokeh looks like, how well the OSS performs and a host of other factors to decide how great (or not) the lens performs in the real world. But these preliminary results look very good.
NOTE: As of May 8th, Canon has issued a recall of affected units. My hat is off to them for superb Customer Care. I didn't dream it could be done this quickly.
Every once in a while we notice something, because of the large quantities of cameras and lenses we buy, that we think people should be aware of. This particular issue won't affect our renters; we've sent the affected cameras back. It may not affect very many people at all, since this is from a relatively small sample size. But I still think it worth mentioning.
The bottom line is that 4 of the Canon T6s and 2 of the T6i cameras we received had to be sent back because of a defect in the sensor stack (the layers of filter glass over the sensor). This is out about 10 copies of each; the others were absolutely perfect.
The affected cameras all had a dramatic pattern that at first we thought was oil or dust on top of the sensor glass.
Affected Canon T6s sensor, Lensrentals.com 2015
But when the techs couldn't clean the 'dust' off, they alerted us. Closer examination with a 10X microscope show the spots are inside, within the stack and under the top layer of glass. I would assume it's a defect in the adhesives used to put the layers of glass together, but I don't know for certain. One person has suggested there may have been dust on the glass when the adhesive was applied, which seems logical, but again, I have no real knowledge of how it happens.
The affected cameras all looked exactly the same, so I won't bore you with more images. It's quite easy to see, even without a sensor loupe, so don't make yourself crazy trying to find it on your camera; if it's there, you'll notice it. Actually it's easier to see without a sensor loupe. Angled light seems to show it up very clearly, lights shining directly down on the sensor not quite as much. The other cameras had no signs of this at all, so it was either a 'yes' or 'no' situation. We didn't see any cameras with just a few dots.
We took a number of images to see how much they would show up on an actual photograph. In wider aperture shots, as you'd expect, they don't show up at all. At about f/11 to f/16, taking pictures of sky, clouds, or a well-lit white wall, they do become apparent, but they aren't as bad as I would have expected.
They're also have a very different appearance than dust on the sensor does. These have have a ringed, or target appearance rather than the dark blob that sensor dust has. Below is a 100% crop from the corner of the camera with the sensor pictured above. Remember, this is an f/16 image of a clear sky. In a regular photograph at wider apertures I doubt you'd notice it.
f/16 sky image from affected camera. Lens rentals.com, 2015
Here's another image that is contrast boosted quite a bit, showing the bulls eye pattern a bit more clearly.
Contrast enhanced f/16 photo showing the pattern is very different than dust on the sensor. Lens rentals, 2015
All of the cameras we received had early serial numbers, and there is not going to be a direct serial number correlation with the problem. For example, we had 7 cameras in the SN 0220310007X range. Cameras with the last digit of 2 and 4 were affected, but 3 and 6 were not. That's not surprising, really, since sensors would be manufactured somewhere else and then placed into the camera during assembly.
I've talked to people at Canon about this issue and they are aggressively looking into it. It will take some time for them to figure out what the issue is, where it occurred, and what cameras might be affected. They're actively looking into the situation. They are NOT telling me, as some manufacturers do, that there is no problem.
My guess, and it's just a guess, is that a bad batch of sensors were made, quality control missed this, and they got put into cameras. How big is a batch? I have no clue. Maybe it's just a few hundred and we happened to get a lot (all of the cameras we've received have been pretty close in serial number). Maybe it's thousands. Time will tell and I'm comfortable the problem is being addressed.
Oh, and for those of you who want to bash Canon quality control over this, well it's appropriate, I won't stand in your way. But I can't because when I looked at these cameras myself the first time, I missed two of the ones with bad sensors. Like I mentioned earlier, direct light through a sensor loupe didn't reveal it nearly as well as an angled spot light did. It's possible the inspection of the sensors after assembly is done using a direct light, or some other automated equipment that isn't capable of seeing this.
So I'm not throwing any stones out of my glass house. And having dealt with many manufacturers concerning many issues over the years, I'm just pleased that this issue is being taken seriously and investigated immediately. That's not always the case.
In the meantime, check your new T6 when you get it, return it if you need to.
Roger Cicala and Aaron Closz
Addendum: I originally speculated that the problem might be in the adhesives used between layers of glass in the sensor stack. Several people, at least one of whom is an engineer in the industry, have emailed to tell me it appears much more likely this is a defect in the sputtering process used to coat the glass in the stack. Assuming this is the case, the problem would be visible immediately, it's not something that would show up later after originally appearing normal.
This past week, I had the unique opportunity to go to the National Association of Broadcasters' trade show, more commonly known as NAB. To say NAB is massive, is a gross understatement; with over 100 thousand people in attendance, and over 1 million square feet in booths and other showrooms, NAB is one of the largest expos and trade shows in Las Vegas. LensRentals was there to see all the new products as they were announced, as well as supply gear for Post Production World - an educational function held within the NAB trade show.
Given the size of NAB, it's nearly impossible to see everything this show has to offer. Hundreds of booths are placed within the Las Vegas Convention Center, making it incredibly easy to get overwhelmed, exhausted, and even lost at times. Even after a full 3 days of walking the showroom floor, I am convinced I missed a thing or two, and wasn't able to see everything that NAB has to offer. That said, here are some of the biggest and best products I noticed while walking NAB show room.
Those of you who read our teardowns know that we commonly are tearing down Canon or Nikon mount lenses. The reasons are pretty simple and it basically comes down to the fact that we have a lot more of those lenses. If we have a lot more it's less of a problem to take a couple out of stock for a teardown. Plus, we're more likely to be doing repairs on them in-house so we need to know the layout. Not to mention, since we spend most of our day inside those lenses, we know our way around them pretty well and don't look to stupid when we do a teardown.
But people who shoot Sony, or Pentax, or micro 4/3 ask us to rip apart their lenses, too. We've avoided doing that because of the above reasons and because we rarely try to repair them. But in the last few months, we've gotten motivated to look inside Sony E mount lenses. Partly it's because we're carrying a lot more of them. Partly it's because repair costs on Sony lenses have become — well I like Sony, so let's just say "fully valued."
A few days ago, we sent a Sony 24-70 f/4 ZA OSS to repair because it made a grinding noise and wouldn't autofocus properly. That kind of thing happens all the time and the repair cost at most manufacturers is $200 to $300. When the service center told this would be an $800 repair, we decided to have them send it back and take a look inside ourselves.
"Self Portrait in a Vario-Tessar". Lensrentals.com, 2015. Call for print prices.
Sony has just released a new line of full frame FE lenses that will hopefully eliminate the need to use adapters with lenses from other systems. We just received the Sony FE 35mm F/1.4 ZA Distagon which has the largest aperture in the lineup and we couldn't wait to have a look at it. Will this replace the petite FE 35mm F/2.8 ZA Sonnar? Probably not for the photographer who enjoys fitting a camera/lens combo in her purse. For the low light lover, bokeh buff, and adapter averse? Let’s find out.
Before I show you fair comparisons of each lens at F/2.8, here are photos taken with each lens at its widest aperture.
Both images were captured on the same camera and tripod setup, so it looks like the Distagon is actually a touch wider even though they are both technically 35mm. Will this make a difference? Not really.
Sony FE 35mm F/2.8 ZA Sonnar at F/2.8
Sony FE 35mm F/1.4 ZA Distagon at F/1.4
And now for a better look at those out of focus areas I threw the focus ring all the way to the closest focus. With everything blurred it is easy to notice the variations in color between the two images. The shape in the highlights is slightly different with a noticeable increase in softness in the 35mm F1.4.
Sony FE 35mm F/2.8 ZA Sonnar at F/2.8
Sony FE 35mm F/1.4 ZA Distagon at F/2.8
Time for the contrast challenge. Here is a mix of light and dark subject matter in bright sunlight. Both lenses seem to handle the situation without obvious aberrations, but the solid background makes it easy to see the vignetting in the 35mm F/2.8.
Sonnar at F/2.8 1/5000 ISO 100
Distagon at F/2.8 1/5000 ISO 100
Another thing to consider with these two lenses is the difference in minimum focusing distance. It's handy to purpose wide angle lenses as macros when possible. The FE 35mm F/2.8 has a minimum focusing distance of 13.8in while the F/1.4 version lets you get as close as 11.76in. And in my experience, 2 inches can really make a difference.
Sonnar at F/2.8 1/2000 ISO 50
Distagon at F/2.8 1/2000 ISO 50
Okay, onward and upward (literally). Let's take a look at flare. As I have noted, the 35mm f/1.4 has a more buttery quality in the out of focus areas. When put against the sun it doesn't seem to hold together as well as the f/2.8 version, exchanging creamy blur for flatter color and more blown out highlights.
Sonnar at F/2.8 1/5000 ISO 100
Distagon at F/2.8 1/5000 ISO 100
And for the final event, landscape photographers, here are two images shot at f/8 focused at infinity. Again, the vignetting and color in the sky is noticeable. What we really want to know, though, which one is sharper. Right?
Sonnar at F/8 1/500 ISO 100
Distagon at F/8 1/500 ISO 100
This is an interesting comparison. The center of each image is very comparable as shown in the 100% crop. You may notice, however, that the edges of the 35mm F/1.4 lose some clarity. This is especially apparent on the left side of this particular image. This is not a flaw of the lens, but due to the curvature in the field of focus. It's commonly thought that the wider the aperture, the sharper the lens is stopped down. We have seen in our labs at LensRentals that this is often not the case. Many lenses made to open as wide as F/1.4 are built with a field of focus pattern that have one or several curves making them less desirable for shooting landscapes or architecture.
Sonnar at F/8 1/500 ISO 100 (100% Center Crop)
Distagon at F/8 1/500 ISO 100 (100% Center Crop)
One last thing to consider when comparing these lenses is the size. The 35mm F1.4 weighs in at 1.39 lbs while the smaller 35mm F/2.8 is only .26 lbs. The weight alone could be a deciding factor.
I'm really impressed with the image quality of the Sonnar F/2.8. This lens is tiny, sharp, and half the price of the Distagon F/1.4. Am I a sucker, like many others, for the smooth F/1.4 lowlight capable lens? Definitely. And I will probably use it whenever I am renting. For the consumer looking to purchase, however, the FE 35mm F/2.8 looks like a smart choice.
Most of you know I've been very impressed with Sigma's new Art lenses. Their 35mm f/1.4 Art I still think is the sharpest 35mm prime lens made. The 50mm f/1.4 Art is also superb.
When I heard about the Sigma 24mm f/1.4 Art lens, I had some mixed emotions. I was excited that we might get a 24mm lens of similar quality to their 35mm. But the logical side of me thought that perhaps Sigma had bitten off a bit more than they could chew this time. Designing a wide-aperture 24mm lens is much more difficult than designing a fast 35mm lens. Even the best 24mm f/1.4 lenses (I consider the Canon 24mm f/1.4 L to be the best current offering, although that's arguable) still have distortion, aberrations, and some edge softness.
But when our first five copies of the Sigma 24mm f/1.4 arrived, I swiped them from intake and took them over to the testing lab for a quick look and MTF testing on our optical bench. We already had results from the Canon 24mm f/1.4 L, the Nikon 24mm f/1.4 ED AF-S, and the Rokinon 24mm f/1.4 lenses in our database to compare them to.
As usual, MTF testing was done for five copies of each lens. Each copy was tested at four rotations (0, 45, 90, and 135 degrees) to give an average MTF across the entire surface of the lens, and the results for each lens then averaged. Prior to MTF testing, all lenses were double-checked on OLAF, our 5-micron pinhole collimated testing machine, to assure they were well-centered. Since the Sigma was the focus of this post, I'll show its MTF curves compared to each of the other 24mm f/1.4 lenses.
Legend for all the MTF graphs
For those of you who don't speak MTF, I'll summarize a bit. In the center 1/2 of the lens (from 0 to 10mm) the Sigma clearly is more contrasty and has better resolution than even the Canon lens, especially at higher (40 lp/mm and 50 lp/mm) frequencies. In the outer part of the image (from 15mm to 20mm) though, the Canon and Sigma are about the same. The Sigma is better than the Nikon all the way out to 15mm, but again, in the outer areas there is either no difference or the Nikon is slightly better.
The Rokinon is a rather different lens. It doesn't resolve as well as either the Nikon or the Canon, and not nearly as well as the Sigma in the center of the image. The Rokinon's advantage is that its curves remain flat almost to the very edge of the image circle, and again in this outer 1/4 of the image it is as good as the Sigma, or perhaps a bit better.
What the MTF curves suggest, then, is that Sigma has made the best resolving 24mm lens in the center of the image, but at the outer edges they've run up against the same aberrations and problems that designers of 24mm lenses have always faced, and haven't managed to overcome those.
Those of you who read my blog regularly know I'm not a huge fan of sameness. But new lens releases, lately, have tended to have a lot of sameness. Don't get me wrong, there have been some excellent lenses released; marked improvements and refinements have taken place. Other than (arguably) the Canon 11-24 f/4 lens, though, there haven't been a whole lot of exciting new designs that aren't like anything else on the market.
Most of you also know that I'm friends and coworkers with Brian Caldwell (the man who designed the Coastal Optics 60mm Macro, Metabones Speedboosters, and a number of other great optics) and Aaron "The Lens Whisperer" Closz, who I'm certain is the best person in the U.S. at optically adjusting lenses.
So one day, we all went out to lunch. One beer led to another, and pretty soon we decided what the world needed most was another lens manufacturing company, and we were just the boys to do it. Brian knows everything there is to know about lens design and likes to think outside the box, so he was an obvious choice. Aaron knows everything there is to know about optical testing and adjustment and likes to think outside the box, so he was an obvious choice, too. I write a blog and was paying for all those beers, so that got me included.
Next we needed a catchy name. With Caldwell, Closz, and Cicala being the founders, the name was obvious: C-4 Precision Optics. Why C-4 you ask? Well, there are several versions of that. It could be because there was a lot of beer being consumed at lunch and our counting skills had deteriorated. Or it might be that there's a silent 4th partner (there is, actually, but her name doesn't start with a C). Or perhaps we feared that C-3 would lead to a bunch of Star Wars jokes. No wait, I just realized that my name has two C's in it, so that's 4 C's total.
Plus we liked the whole explosives tie-in. The only things cooler than optics are explosives. Unless we had some exploding optics or were making optical explosives or something. So we got a cool logo made, and opened up shop. Then we dropped the cool logo because Brian hated it, and well, it's hard to have a lens designing company without a lens designer.