You are in the minority when you say the atrocious bokeh of CV 35/2 does not bother anyone. Sales figures of that lens will tell Cosina what not to do again.
vdo1 wrote:
"Rendering". That ineffable quality that can be always invoked to defend one's preferences against some measurable evidence.
It's applicable though only when convenient. Just check how the Voigtlander APO 35/2 atrocious bokeh doesn't seem to bother anyone.
I don't think APO's intended audience will care about subpar bokeh, there are noktons for that...
I'd be more worried about the GM though ...
realVivek wrote:
You are in the minority when you say the atrocious bokeh of CV 35/2 does not bother anyone. Sales figures of that lens will tell Cosina what not to do again.
j4nu wrote:
I don't think APO's intended audience will care about subpar bokeh, there are noktons for that...
I'd be more worried about the GM though ...
Ah the Noktons... they have purple fringing, LoCa, onion rings, cat eyes and other ailments, but no one is bothered by those either.... Their "rendering" is not to be questioned. Because "Nokton". They have "character" unlike "sterile" lenses.
The GM (from the images thread) is sitting pretty.
j4nu wrote:
I don't think APO's intended audience will care about subpar bokeh, there are noktons for that...
I'd be more worried about the GM though ...
Jonas B wrote:
Hmm... Your napkin may be out with a factor of ten. Then again I also make mistakes... but I suspect something is off with your numbers. Logic also tells us that every lens test made at a short distance is impossible, or close to impossible. Yet people, all IMA-test folks and so on have done this for years.
Anyway, it doesn't matter really as:
a) I can repeat the test easily
b) other lenses work fine with the same setup
c) Check the "resolution" curves I showed and you'll see the Sigmas were better when checked at the right most patch (patch 7) than they were at patch 6. That can then be compared to the result Lenstip showed in their review. ...Show more →
Yep, it's just very hard to test lenses accurately - especially at such short distances and such high spacial frequencies up to 60lp/mm. Alignment just becomes so critical. I just don't think you can test up to 60lp/mm accurately in a home setup at under 1m distance, the DoF is just too shallow and there are too many (6) degrees of freedom in setting up a camera. Heck, even the flatness of your shelf front could matter - some testers even dry the paper of their charts in an oven to minimize curling problems due to humidity. I found documentation for a photo magazine testing film lenses at 55 times focal length - that'd be about 2 meters, but lower lp/mm than 60.
The math is pretty simple, mostly just basic trig. Let a = sensor to target, b = imaged length of the shelf/2, c = sensor to "patch 7" diagonal distance, d = a + depth-of-field_at_distance(a). FOV horz 35mm is 54.4 deg, so half-angle theta is 27.2 deg. You just need to calculate c = a / tan(theta) and then solve the "opposite" angle of the triangle with hypotenuse c and adjacent d, so we have theta' = 90 - arccos(d/c) and then the difference theta - theta' is the max allowed angular deviation to stay within DoF.
I could be off by a factor of 10 but a quick check using the old physics trick of "projecting" a force (cos of angle times magnitude of force) shows that an 8 degree error moves back the right edge focal plane by 5.3cm, 4 deg by 2.8cm, 1 deg 8mm, so that looks right to me, based on your 60lp/mm chart your acceptable DoF is 8.5mm.
It would be interesting if you could replicate your findings at longer distances - the problems should also show at other distances if the elements are misaligned or even incorrectly ground. You should see a marked difference in image quality of the edges at infinity.
vdo1 wrote:
"Rendering". That ineffable quality that can be always invoked to defend one's preferences against some measurable evidence.
It's applicable though only when convenient. Just check how the Voigtlander APO 35/2 atrocious bokeh doesn't seem to bother anyone.
Nonsense, rendering can be measured in blind tests like nehemiahphoto did recently on the alt forum. It can be just as measurable as anything else, and is applicable for any one who makes it part of their evaluation of a lens. The APO 35 f/2 is sharp but it does not do well in such tests of rendering. I wouldn't say it bokeh is atrocious, but I would say it is quite busy int he transition zone and it is fairly high contrast.
I think Fred's tests of rendering in this thread are a quite useful part of the review he did here.
vdo1 wrote:
Ah the Noktons... they have purple fringing, LoCa, onion rings, cat eyes and other ailments, but no one is bothered by those either.... Their "rendering" is not to be questioned. Because "Nokton". They have "character" unlike "sterile" lenses.
Another big mischaracterization of Voigtlander lenses. These are f/1.2 lenses. Wide open they have lots of aberrations, but stopped down a bit they do have nice rendering especially in the transition zone. They do have cat's eyes until well stopped down, but onion rings are exceedingly rare. Of course their rendering can be questioned, but that doesn't mean some people don't like what they have to offer.
Apr 20, 2021 at 09:32 PM
Steve Spencer Offline • • • • • • • Upload & Sell: On
Yes, the CV 40/1.2's specular highlights can show onion ring pattern although not the worse I've seen. The 35/1.2 III and 50/1.2 Nokton lenses not so much. Sony is doing better with their aspherical molding process compared to Sigma.
The Nokton's focus transitions are generally very smooth but rendering is not perfect:
There is strong axial CA at f/1.2
Cats' eye bokeh off-axis at f/1.2
It's the compromise for having super fast + compact lenses. Many of us love the images they produce and they should only be compared to other ultra fast lenses that are compact as well.
i35 is glued to the a7c. Almost perfect for everyday stuff. Somehow Capture 1 thinks this is Loxia 35. Maybe C1 thinks it's like Loxia with autofocus and softer transition.
chiron wrote:
I'm assuming that you keep the tripod in place as you go through the different Sigma lenses. If so, one way to get some evidence on whether it is your setup or the lenses creating the softness would be to break down your setup (tripod, camera, lens, and including dismounting the test charts) and then set it all up again and retest one of the lenses with the second setup.. If the flaw is in your setup, it is very unlikely that your error would occur in the same way a second time. If you get the same results with the second setup, it points to the lens. Alternatively, you could do an equivalent test in another room with different targets. ...Show more →
I get your point and it's not bad at all.
However, I never had more than one of the Sigmas at hand at any given day. Borrowed, returned, ordered and returned... and I didn't keep the last one either.
So, the test shots with the Sigma are all taken different days and can't be repeated.
But, doing some alterations...I'll do that if I get another lens not working as expected. it doesn't happen often.
...
