As you can see, the LoCA signature is different than is typical. Most often you'd find a green/red split between fore- and back-ground. Here, we see that they managed to get the background fairly well corrected. The two colours are still there, but they are blended fairly well into a more neutral (and smooth) tone. In order to do this, it seems they needed to sacrifice foreground LoCA which gets a fair dose of both red and green. They made the same sacrifice of the foreground bokeh for the benefit of the background, as well.
So, the conclusion is; watch out for high contrast stuff in the foreground bokeh, but LoCA is not going to be an issue on the Rokkor under most conditions.
Tariq Gibran wrote:
That is a very good performance for a non APO lens I would say.
Ya, I think so, too. For a non-APO f1.2 lens.
People talk about how the price has skyrocketed on this lens. To me it is no mystery. The fact is, it was incredibly de-valued for the longest time due to an abandoned mount. Converting them simply restored their value, and restored value even to the unconverted ones.
>Don't bring out too much of this stuff, it will drive up Rokkor prices!
They are already pretty damn high. ;-P
property-tax time in canada too, eh? ;-)
thanks for the examples and testing.
btw, the rokkor predates the Nikkor Noct, so I wonder if there was licensing/copying involved if the noct copied rokkor optical formula? maybe the patent office has some info...
I see no association between the Nikkor Noct and the Rokkor 58/1.2. The Nikkor Noct, if I am not mistaken has a hand figured aspherical element which the Rokkor 58/1.2 does not.
The 2 lenses do not even share the same optical formula. The Rokkor 58/1.2 is a 7 element in 5 group configuration, and the Nikkor Noct is a 7 element in 6 group configuration.
Some around here like to go off on promotional campaigns, even if it's not well deserved. Comparing it to the Nikkor Noct without some solid comparative data is close to ridiculous. I tested a Rokkor 58/1.2 against my excellent Zuiko 50/1.2. Here are the results of both for LoCA. The Zuiko is the clear winner in my conclusion:
The Zuiko appears to be a little faster (per the histograms)
The Zuiko has a much closer focus distance
The Zuiko is sharper in the corners when used stopped down
The Zuiko has better color
Just this week, a thread with quite a lot of data (a report in a pdf) was posted as to resolution/performance caractheristics of among others, the rokkor, those insinuations you are making doesen't really do anyone any good Please try to stay on the rational level, avoid ad-hominems, implied or not.
Nov 02, 2008 at 06:29 AM
Steve Spencer Offline • • • • • • • Upload & Sell: On
Thanks for adding your test to the earlier ones by Paul (cogitech). I see the tests as quite complimentary. Here are my thoughts. Both lenses seem to do quite well with LoCAs. Like Paul (cogitech) noted, however, the Rokkor does better with them in the area behind the focus point and not nearly as well in the area in front of the focus point. I think I see that pattern in your test as well--Yom seems cleaner than the 8. Interestingly the Zuiko seems to show the opposite pattern--at least to my eyes. It seems to show more LoCAs behind the focus point and less in front of it. I also suspect you are quite right that the Zuiko has a closer focus distance (close focus distance is not one of the Rokkor's strengths) and the Zuiko might well also be sharper in the corners when stopped down. I personally would not use my Rokkor for stopped down applications in which I care about the corners. Many lenses can handle this well, but I use the Rokkor for wide aperture low light portraits, so soft corners stopped down wouldn't bother me and I suspect most people who have this lens. It is good to know its limits, however. Now colour that is of course much more subject and if one had a radioactive Rokkor and the glass was still even a bit yellow this obviously might affect the colour as well. So picking a winner on colour is likely to be difficult. Anyway thanks for sharing your test.
Thanks guys for all your perspectives. Especially Paul (Cogitech) for giving a helping hand to those who have limited experience in alternative lenses. this seems to be very subjective. The bottom line is the Rokkor 58 1.2 is an amazing lens that those who have are enjoying! Thanks again Paul for your insight.
Yes, I posted that thread with the PDF report from BJP.
re: noct vs. rokkor formula - was just repeating what Paul had passed along regarding the similarity of them (minus the aspherical of course). I haven't researched it myself enough yet to say one way or the other.
Groups I'd think would matter some, but even with different groups you could still have basically the same formula. one would just use an extra air lens, presumably. All academic for the most part - we need to do more shooting and less yapping about it all.
First off, I agree with Steve's analysis of Paul's (pdmphoto) test shots. From what I see (and from my own analysis), my choice would be the Rokkor. I typically care much more about background LoCA (and bokeh) than I do about the fore-ground. I also find the Rokkor's colour to be superior (right across the Rokkor line, in fact). That is subjective.
Regarding the Noct-Nikkor vs. Rokkor comparison, all I have is this statement from a student of optics at a European university, whose group recently studied all these ultra-fast lenses:
"... today I met Mr. Zörkendorfer, the main alternative lens guru in Europe (a former Arri and Mamiya engineer and an a credible inventor in our field, see: http://www.zoerk.de/ ). Beside the main project that we are doing with him right now, I showed him the 58/1.2 Rokkor... He said, the lens is identical in optical formula and calculation, just not coating with the Nikkor."
I'll not be the one to challenge Mr. Zörkendorfer on this issue.
Since Paul is quoting me (Zörkendörfer on Noct-Nikkor), after a long while of being inactive here a clearly unsatisfying hint from my side:
At the named university laboratory we have compared all available 1.2 SLR lenses, including the Contax 55mm, including the rarest of them all (Noctilux R 1.2) excluding the Konica Hexanon 57mm (impossible to use with 1DsIII because of register) about one year ago.
We had (in many cases two copies) these at hand: Canon FD SSC 55mm, Canon FD SSC AL 55mm, MD Rokkor 50mm, MC Rokkor 58mm, Nikon Nikkor 50mm, Noct-Nikkor 58mm, G. Zuiko Auto-S 55mm, Pentax SMC 50mm, Yashica ML 55mm, Contax 55mm, Leitz Noctilux-R 52mm f/1.2 prototype (borrowed).
I never had the time to upload the test results. We did MTF's, real life test photos at infinity, 35m and closest distance possible, studio and available light...
Surprise: If sharpness and resolution center wide open is in question the Pentax beats all other lenses by a clear margin. At f 2.8 to f 5.6 the difference gets smaller with the non-AS Canon and the Contax leading. Bokeh seems to me to be a mere aesthetic property, not an intersubjective one. Regarding flare, CA and distortion the Contax appears to be the best.
The 58mm Rokkor in use, was converted by Paul. I am sorry we did not have a radioactive copy for the comparison.
(By the way: Do you gear-guys happen to know the work of John Gossage? The main man in art photography and conceptual using thin DOF. Recommended: His Book "The Romance Industry".)
The Zuiko 50/1.2 has less LoCA in forground and background. These shots were taken at diifferent angles (due to the focal length differences), with the Zuiko shot taken at more of an angle. The background stuff you see is mostly just out of focus blur. In the variois shots I took it was easy to see the LoCA in the foreground/background of the Rokkor shots, but not in the Zuiko shots.
I also see that no Zuiko 50/1.2 was included in the testing, too bad (especially a good copy). While it doesn't have quite as nice bokeh as the Rokkor (which really only has nice bokeh when stopped down some), it is sharper wide open (as my test shows), and has better color. Maybe I'll get around to posting my color test, but the Rokkor mutes the greens compared to the Zuiko.
I've definitely noticed the LoCa in the FL 55 (I hope you don't feel like this is thread-jacking... I've added bits about the FL since that's what I have and there seems to be only a few of us using this f/1.2 lens). I haven't had a chance to do any real tests, and I don't have access to all my files right now, but it would be interesting to try an example of what you shot above. I definitely think that the FL shows more LoCa than the Zuiko... maybe more than the Rokkor. It also glows quite a bit wide open, which seems to make the problem worse.
Anyway, hope my input adds to the discussion... and I hope no one thinks I'm bashing the Rokkor (I'd like one!).
