DPReview.com is closing April 10th - Find out more

Sharp, nice bokeh -- great lens!

Started Dec 27, 2019 | User reviews thread
J A C S
J A C S Forum Pro • Posts: 20,521
Re: Sharp, nice bokeh -- great lens!

medon78 wrote:

J A C S wrote:

medon78 wrote:

...

Some testers say, this lens would exhibit extreme vignetting. Well, looking at the example below (far from scientific, true!) I can see a 1.5EV difference in the corners between f/1.8 and f/5.6 in the RAW file. That does not bother me too much, since in-camera correction reduces this even further.

You are comparing different exposures and different ISOs... Optical Limits measured 3.8 EV vignetting, which is pretty extreme. I checked their numbers of other lenses (I do not own the RF 35) in RAW, and their numbers are quite close to mine. DPP measures extreme vignetting as well.

Yes you are right, the ISO were different in the real world snapshot.

I re-checked with fixed ISO against my white ceiling, with 4 variations -- lens corrections turned ON/OFF, focus set to infinity vs. focus at 0.5m.

Seems the both variables "focus" and "lens corrections" do not affect vignetting, maybe the focusing distance changes corner exposure by ~0.2 EV. Not too significant.

Result: Yes, vignetting is stronger compared to my initial 1.5EV statement; now it is close to 2.0EV.

I am sure the guys at Optical Limits have more sophisticated measurement methods and tools at hand, though. OR -- maybe the R and RP exhibit different vignetting thanks to different micro lens design. Don't have an EOS R at hand, though.

Cheers!

This is interesting. Would you share that RAW file with me? I can share some RAWs of my 50L with the R and the 5D4 if you want.

I found it tricky to measure (and even define) vignetting. It depends how directional your source is. Walls/ceilings are good targets but they can be a bit too directional. I tried putting a napkin over the lens and when I point it to a light source, for example, I still see a hot spot.

I measured about 2.2 stops for my 50L. If I choose the center to be strictly the center, and measure the corners in the extreme corners with a small box, I get a bit more.

Keyboard shortcuts:
FForum PPrevious NNext WNext unread UUpvote SSubscribe RReply QQuote BBookmark MMy threads
Color scheme? Blue / Yellow