p.3 #1 · Diffraction the great equalizer? (Guess what the lenses are)
That is a very interesting test, Tim. It's amazing how much difference there is on the Loxia in the outer zones between f/11 and f/16. And, it may just be my eyes or my monitor, but it looks like there's a bit of color shift in the upper left corner on the f/16 shot.
p.3 #2 · Diffraction the great equalizer? (Guess what the lenses are)
Yes, I noticed the magenta in that corner too. I'd be curious if someone else with a Loxia 25 sees the same thing.
-Tim
freaklikeme wrote:
That is a very interesting test, Tim. It's amazing how much difference there is on the Loxia in the outer zones between f/11 and f/16. And, it may just be my eyes or my monitor, but it looks like there's a bit of color shift in the upper left corner on the f/16 shot.
p.3 #3 · Diffraction the great equalizer? (Guess what the lenses are)
I remember that diffraction busting feature, but I can't imagine it's in play here. If it were, I would expect less of a difference as you stopped down the Loxia. I wonder if it's part of the on lens profile, in which case it's possible that the Loxia might not have it. I can't remember if it was baked in the RAW file.
-Tim
realVivek wrote:
Tim, When Sony introduced the A7R, they elaborated on how the system lenses would miminise the diffraction effect digitally.
With the Loxia having a chip (albeit lacking the distance information) would help the camera to do that. Any non system lens would lag behind when it comes to this.
p.3 #4 · Diffraction the great equalizer? (Guess what the lenses are)
I love the look of the Pentax, but you're kind of limited to having to stop down for shooting landscapes. For however amazing it is for a lens of that age, modern lenses are even more amazing for their performance at wider apertures.
If you can live within its limitations, it can deliver very nice results. Some of my favorite shots are with that lens and it's part of the reason I give it some camera time.
p.3 #5 · Diffraction the great equalizer? (Guess what the lenses are)
Another cheap lens that delivers way above its pay grade is the Zuiko 28 f3.5. Great contrast and colours and sharp when stopped down to 5.6. Weighs nothing...costs about nothing.
p.3 #6 · Diffraction the great equalizer? (Guess what the lenses are)
I don't see any magenta corner issues on my Loxia 25 (on A7RII).
It's almost criminal (to me) to stop the L25 down to F16. At that aperture I would expect loads of cheap lenses to do almost as well as much more expensive ones, at least in easy lighting conditions like this.
p.3 #7 · Diffraction the great equalizer? (Guess what the lenses are)
Greens are more fruity (yet flatter) in the Loxia 25 here too, Pentax neutrals are creamier (Loxia clinical), Loxia has duller green/yellow transitions. 43 years on, the 28/3.5's strong colour performance is close to the heritage Zeiss lenses' signature. I have a lot of blue sky and my modern optics drift away too readily into an uneven pale cyanish mess. Not what your eyes see.
Phillip Reeve on the 28/3.5:
'What surprised me the most was the truly exceptional flare resistances and very high contrast. I didn’t know that a 40 years old lens could be that flare resistant. The Pentax is even better than the Zeiss Distagon 2.8/28 in this regard.'
It's a 6/6 design (180g), the CY 28/2.8 is 7/7 (280g), the Loxia 25mm is 10/8 (390g). Then new glass (asph/APD), coatings, tolerances, stray light, etc. Progress. The old light little lenses are so easy to use for landscape/general use.
p.3 #9 · Diffraction the great equalizer? (Guess what the lenses are)
Went looking for info on the a7r 'diffraction correction' technology. Just summary mentions at release time, including:
'Another function promised by the Bionz X processor is 'Diffraction Reduction', in which the camera's processing attempts to correct for the softness caused by diffraction as you stop a lens' aperture down. This processing is presumably aperture-dependent..'
'SONY’s A7R uses a unique diffraction correction function aimed to correct such effects. This distinctly improves taking images with an aperture as low as F11...However, SONY A7R’s diffraction correction feature does not support RAW images. The editor feels that to be able to fish out and prevent diffraction problems makes one practically a serious photographer.'
p.3 #11 · Diffraction the great equalizer? (Guess what the lenses are)
So anyone want to play another guessing game? Here are 3 shots taken with 85mm'ish lenses, all at f/16 on an a7R III. They were all processed in Lightroom with same sharpening and contrast setting. Exposure and color balance were adjust to try to get them reasonably close to each other. They were all run through Topaz Sharpen AI with the "auto" setting. For me, both prior to, and after running these shots through Topaz, I'd put them in the same order. While the differences are subtle, with a tool like Photo Mechanic you can pan across two shots and it helps at least me judge that there is a difference.
What order would you rank them in for sharpness/acuity?
No need to play if you're not interested in playing....
One of the shots has EXIF, the others don't. Some of the differences may be due to depth of field differences in the way the lenses put the depth of field in relation to the plane of focus.
Again, probably a silly exercise for most...but I find it a little interesting.
p.3 #13 · Diffraction the great equalizer? (Guess what the lenses are)
Digging up a blast from the past. I believe the Loxia I had in the tests above was slightly decentered. Here's a comparison between what I consider an excellent copy of the Loxia 25 against the Pentax 28/3.5 (Fred's copy actually) at f/11. The trick is that it's at f/11, I can get sharper results from the Loxia 25 at wider apertures, but I'm also willing to stop down to f/11 for added depth of field. I love this Loxia 25, but I also love the Pentax (and I love the Sigma 28/1.4 as well.)
This was shot on a higher resolution sensor than the tests I did above. I personally think the Pentax performance is amazing given that it's a 45+ year old lens. I tend to shoot the Pentax at f/11 though, as the corners start to drop off as you open up further.
Note as well, I tried to keep the foreground similar, I was close, but not perfect. Notice the change in perspective between the 2 lenses. The "zoom with your feet" guidance sort of falls apart when you see that there is an impact in perspective that people often forget.
These were processed in Lightroom where I balanced the exposure and color temps between the two lenses. The contrast is set the same, as well as sharpening. I did apply distortion correction to both, for the Pentax I used the Pentax 31 Limited profile as I feel it's a very good approximation for the K28/3.5. I did sharpen them both in Topaz Sharpen AI, but used the exact same settings there.
I've always felt the Pentax "fit in" with my Zeiss lenses. It even seems to have some of the similar field curvature behavior of the wider Loxia lenses. The Loxia is better, no doubt, but closer than I would have guessed.
