Originally posted by Digitalis Takes A deep breath
from my testing the pentax K 50mm f/1.2 has a different resolution characteristic from the canon 50mm f/1.2 which I own and use from time to time. In my testing with a pentax LX on T-Max 100 at f/2.8 the SMCP 50mm f/1.2 has higher overall resolution in the periphery of the imaging field than the Pentax SMCP-FA 50mm f/1.4. The Canon 50mm f/1.2L is close to the SMCP 50mm f/1.2 @f/2.8 however the image quality at the edges of the frame are a bit softer in comparison to the SMCP 50mm f/1.2
The SMCP 50mm f/1.2 has extremely low Purple fringing*,however it does possess transverse chromatic aberration which is exacerbated at closer focusing distances, it is most apparent at the periphery of the imaging field. It is my personal opinion in regards to optical aberrations the Canon 50mm f/1.2 is an inferior performer when compared to the SMCP 50mm f/1.2
The DA*55mm has higher amounts of PF and CA than the SMCP 50mm f/1.2. The FA 50mm f/1.4 is an old design, but it is basically identical to most of the 50mm f/1.4 "me too" lenses. The DA*55mm f/1.4 uses a different optical formula in comparison to the SMCP 50mm f/1.2 and FA50mm f/1.4 lenses. And since the lenses are of a different focal length it becomes increasingly difficult to quantify and compare results.
In the case of the canon lens no, it really isn't worth it. because the Canon EF 50mm f/1.2L has a T stop of T=f/1.33- the SMCP 50mm f/1.2 has a T stop T=f/1.22(as I recall) so IMO it isn't even worth comparing the two lenses.
the colour and contrast doesn't just vanish, it's still there. what do you think PP,darkroom filters and variable contrast papers are for? Do you expect every image from your lenses to be perfect in colour and contrast? even without application of rudimentary PP? I have never seen a jeweller present a finished ring with an uncut diamond in its setting.
Well that would be a $15,000 mistake. but from my ownership of leica lenses and cameras i'm sure the 50mm f/0.95 ASPH can take more abuse than most lenses will ever be subject to. I use my noctilux 50mm f/1.0 without the ND filter. As Ansel Adams said "If your lens has bad vignetting, use it to frame your subject" those ND filters are for nitwits who obsess over achieving this ridiculous ideal of perfection. The tools we are using are imprecise, compare the shutter mechanism of a Nikon F5 to a swiss designed invar watch movement and the shutter from the F5 will look like a crude contrivance.
*I'm not entirely sure what causes PF, there are hypotheses some claiming it is UV light,some saying it is a sensor defect. I have another theory, but I need more hard data to come to any conclusions. All I know for certain lenses suffer from inordinate amounts of it; FA77LTD and DA 12-24mm f/4 are the worst culprits. Yet, some lenses appear to be remarkably free from it.
I know you're testing a film result against a modern MTF reading, which is why the issue is as speculative as counting angels dancing on the head of a pin.
When Photozone and other sites have gone back and tested legacy glass with high expectations, generally, the legacy glass has not performed well. I am not sure what you mean by "resolution characteristic". It either has the resolving accuracy or it does not. The only way to know is via MTF. Until then a T-Max film res count through a loupe is subjective. And the issue was not how they performed at 2.8, but at 2.0. The Canon 1.2 and 1.4 are equals at about 1.7 and they are modern lenses of comparative vintage. Again, until the testing benchmark is similar, I have doubts that the Pentax A 50/1.2 is superior to a more modern Canon offering. the Pentax has terrific bokeh. The resolution........let's see some real numbers. Prove me wrong. Someone send a good copy of the A 1.2 to Photozone with some pleading. It would be fascinating.
What also speaks volumes is that there has been no 1.2 Pentax released in well over 20 years, and that those from other companies are priced very, very high. You'd think that companies would push these out for the cachet and high margins, but they do not. Likely the reasons are optical quality issues in an age that values resolution and sharpness which they simply cannot deliver, made more obvious in digital negatives. These lenses would disappoint the market as much as excite it.
Yes, loss of contrast can be lost data if it never reaches the sensor through the Bayer filter. I don't expect cameras and lenses to be perfect (Lecia does:
Leica Camera AG - Photography - M9). I do know that the pursuit of ultra-fast glass involves irrecoverable compromises. You get amazing bokeh and a 3D pop in the centre of the frame. Everything else is compromised...by design.
With PP and Photoshop in the equation, the economics of these lenses doesn't make much sense. It is far more cost-effective for the photographer put those resources into software manipulation. Yes, there is data integrity and authenticity arguments, but at these apertures, the competition is Photoshop! Or a Hasselblad:
flores | Flickr - Photo Sharing!
I can't beat this comment from LL regarding the ultra-wide aperture lenses (
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"... I question how long or how often a photographer can use it before he begins repeating himself visually. Rather, a lens like this is a creative tool that’s fun to reach for when you want to do more creative or experimental work."
Most newbies here look for the fast glass solution for a host of issues, such as capturing shots of running kids indoors. The same can be said for the nightclub shots, handheld shots, etc. Too fast glass is not a photographic solution to the majority of real world solutions. Noise-free high ISO sensors, better flash, and PP are.