Resolution Tests
What Actually Happens When You Stop Down a Lens
I got an email the other day that got me thinking. A guy simply asked “How far do I have to stop down a lens to get maximum performance. I’ve heard two stops from wide open. I’ve heard down to f/8. Which is correct?” I asked him which lens he was referring to, and was he talking about the center…
Tamron f/1.8 VC Prime Lenses Sharpness MTF Curves
OK, for the first time I can remember, I’ve been browbeaten into doing a test I didn’t plan to do. When Tamron released their neat little Tamron 35mm f/1.8 SP Di VC and Tamron 45mm f/1.8 SP Di VC lenses, I thought, well that’s interesting, and the price point is reasonable and didn’t think about…
Sigma 20mm f/1.4 DG HSM A1 MTF Curves
OK, here we go again, with what has become a regular routine. Sigma announced another new lens doing what nobody has been able to do before. My expert friends, technical people I ask questions of, all say, “I don’t know this time. I just don’t see how they can pull this one off. Not at that price…
Zeiss Milvus Optical Bench Tests
When Zeiss announced the new Milvus lens lineup, there was a mixture of excitement and yawns. In part, I blame Zeiss’ marketing department for the yawns. OK, I shouldn’t be harsh. I shouldn’t, but I will. I’m certain a lot of people are perfectly comfortable just knowing that the new lenses will…
Sony E Mount Lens Optical Bench Tests
It has taken a long time, the sacrifice of a couple of cameras and lenses, and a lot of soldering, but we have finally managed to rig up a powered Sony mount to our optical bench so that we can test the new full-frame Sony and Sony-Zeiss E-mount lenses. For those of you who haven’t understood why…
35mm f/1.4 Shootout: Canon 35mm f/1.4L II VS Sigma 35mm Art VS Canon 35mm f/1.4L I
Yes, indeed, I learned my lesson. I’ve had MTFs on a few copies of the Canon 35mm f/1.4 Mk II lens for a while now, but I wasn’t about to publish the results until I had a full 10-sample group done to get a thorough look at them. If you don’t like pretty graphs, then I’ll give you the quick summary…
Sigma 24-35mm f/2 DG HSM Art MTF Curves and Sample Variation
For years now, I’ve been telling people to always take the results of tests done on one copy of a lens with a serious grain of salt. Not matter how carefully it was tested, it’s still just one copy. Others will be worse. Others will be better. Because I’m so aware of copy variation, I (in theory at…
Sony a7R II Vs a7S Video Field Comparison
The amazing low-light performance and ability to shoot in 4k has made the Sony a7S a definite favorite for our customers and the LensRentals team. We have been very excited over the release of the a7R II with new features such as 5-axis in-body image stabilization, a 42.4MP back-illuminated…
MTF and Variation: An Example
We’ve spent most of the last month establishing a database of MTF curves and expected copy-to-copy variation for a number of lenses. Most people have a general idea about what we’re doing, can follow along the basics of MTF curves, etc. But many other people also have a very good question, “How…
70-200mm f/2.8 MTF and Variations
Finally, the last in our series of MTF and variation tests is here. We’ll be doing these going forward as new lenses are released but for now we’ve got a nice database of common lenses that we can measure others against. We’ve completed almost all of the common prime lenses, along with wide and…
Wide-Angle Zoom MTF and Variations
We recently published the MTF and variation curves of standard range lenses and now are going to tackle wide-angle zooms. As we’ve seen, zooms have more variation than primes and wide-angle primes have more variation than standard range primes. Also, the MTF curves of wide-angle primes are weaker…
A Quick Look at the New Sigma 24-35 f/2 Art
* Image Courtesy Sigma USA * I generally do MTF testing on multiple copies of a given lens so that I can present the averages, look at sample variation, and stuff like that. I’m always aware that looking at any single copy of a lens, especially a zoom lens, gives only a limited prediction of how…