Lenses and Optics
The Effect of a Decentered Lens on Autofocus
As some of you know, I’ve been testing a large number of Nikon cameras and lenses as part of the Autofocus Reality series. (Nikon full frame results will be up in a day or so.) I noticed an abnormality in one copy of a lens we were testing that some of you might find interesting. We were using 28mm…
Canon Illumination Correction and Third-Party Lenses
I while back I put out a notice that the Sigma 150mm and 180mm OS Macros had an issue if you shot JPGs on a Canon 5D Mk III and left peripheral illumination correction on. The camera auto-corrected for vignetting that wasn’t there, leaving an interesting pattern with a dark center and lightened…
A Tilted Element Demonstration
One thing we preach here a lot is that just because a dropped lens looks fine on the outside doesn’t mean it is fine. The other thing we preach a lot is that a tiny difference in the centering, tilt or placement of a single element can have a dramatic effect on image quality. Aaron made a great…
Imatest Macro Results (With Apologies to the Nikon 105 VR Micro)
A few months back we tested a number of Nikon lenses on the D800 cameras, hoping to determine which lenses could bring the absolute best resolution out of that camera’s 36-megapixel sensor. The results were interesting, and in a few cases surprising. More than a few Fanboys went ballistic over…
Canon’s 18-135mm IS gets an STM Makeover
So the usual happened today: I read in a couple of places that the Canon 18-135mm IS STM lens isn’t going to be available in the U. S. for a while. A few minutes later Tyler walks in my office with one, asking if I want to test it. Let me be clear where I’m coming from: we never stocked the Canon…
Optically Adjusting a Lens
I write a lot about the fact that every copy of a lens is slightly different than every other copy. Now don’t get me wrong: I’m talking slight differences that are barely detectable, not good or bad. Even when things appear to be in the “bad lens” area, they usually aren’t. The majority of the time…
A Weekend with the Panasonic 12-35 f/2.8
Tyler has an amazing ability to purchase hard to find items and get them to Lensrentals. Today he amazed even me — a brand new Panasonic 12-35 f/2.8 OIS lens arrived when, in theory at least, there are none available anywhere in the U. S. None of us know how he does it. I’m pretty sure none of us…
Testing for a Decentered Lens: an Old Technique Gets a Makeover
## What is Decentering and What Does it Do? 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…
Some Mirrorless 5X Macro Fun. (Too much fun, actually).
I generally don’t write separate reviews on items. I put a ‘take’ up on most items we rent, letting people know what I think about it. That lets me be neutral because it doesn’t make me any difference what people rent as long as they’re happy with it: the return on a $10,000 lens and a $200 lens is…
Reflections on Reflections. Coatings: The Most Important Part of Your Lens.
Reflection is an interesting word with many meanings. To a philosopher it means careful or considerable thought on a subject. To an anatomist it means a structure that bends back along the path it came from. To a narcissist it’s their image in a mirror. To a photographer it usually means subjects…
Stop it Down. Just a Bit.
If you read much that I write, you know I love’s me some wide-aperture prime lenses. I like the narrow depth of field that isolates my subject, and the ability to shoot in low light. More than anything else, though, I love a nice sharp lens with superb resolution and excellent contrast. A lot of…
Are Zooms Always Sharper at One Extreme or the Other?
There is a statement often repeated about zoom lenses, which I have assumed to be generally true, or at least historically true. > “All zooms are sharper at one end than the other.” I also hear a lot of people saying they bought Zoom A because it’s sharper than Zoom B. Is that sharper everywhere?…