Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
09-29-2009, 01:01 PM   #46
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,353
Trying to be objective, but it is hardly science and of course partly subjective, I would make the following conclusions on the first set of shots.

The Meyer is the real dog here, the pancolor is not that much better, but have in some shots a nice color. A pitty since I think the Meyer lenses look sexy.

The A*85 and the DA77ltd produce very similar pictures, and they should since they have the same optical solution, with the difference that wide open the 1.4 lens has a thinner DOF and hence less of the plants etc in focus. There is probably two things going on here at the same time: the A*85/1.4 really goes quite soft wide open, then it sharpens up rapidly when you close down (which is confirmed by the later portrait shots). In addition, the thinner DOF enhance this impression. The softness wide open is probably why Pentax limited the limited 77mm to f1.8 since that optical solution is not ideal if you go further. My guess is that at the f2 shoot out, the difference will be much smaller, the A* may even surpass the 77 in sharpness.

The Takumar f1.8 and f1.9...this confirms the feeling I've got from before...and it is a bit odd that the f1.9 does so well against the f1.8 since on the paper the f1.8 should be a better lens...so what comes out of a lens is not always so easy to predict. Some simple lens solutions may be some sort of soft spot in the multidimensional space you move around in when designing a lens. Makes me want a super f1.9. Only good they may go a bit less expensive than the SMC 1.8's.

The M85/2...a limited lens before the limiteds where invented? How does this simple lens does so well against the others? While being so tiny? A mystery like the 70ltd. It's not so good reputation I suppose is only because its been compared against the f1.4 and f1.8 lenses that may be a tiny bit better. The 85/2 has been on my list to Santa Claus for a while. Better be a good boy. Please Pentax take this lens design and tweak it into a DA90ltd f2 too give the 135mm equivalent that are missing in the DA ltd line.

Asahiflex...my compliments on the portraits. Some lens shoot out threads are rather booring due to rather booring and technical test pictures (like your first set), but there are some really good portraits there with the 85/2 and 85/1.4.

09-29-2009, 04:45 PM   #47
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,416
QuoteOriginally posted by glasbak Quote
I will bite,
First, on APS-C I would not call these portrait primes.
Good point, though on 35mm film the 135mm focal length is an acceptable portrait lens and fulfilled that purpose for many photographers back in the day (85 x 1.5 = 128 ... close enough). My experience is that the 77-85mm focal length works well enough for portraits on APS-C assuming you have adequate working distance.

QuoteOriginally posted by glasbak Quote
Second, you cannot judge the corner performance on APS-C, sensor is too small.
The corner performance on APS-C is the corner performance on APS-C. That is why you can't generalize lens tests across sensors/formats.

QuoteOriginally posted by glasbak Quote
Third, if you shoot all wide open, and not at the same aperture, what are you comparing ?
Wide open bokeh.

QuoteOriginally posted by glasbak Quote
Fourth, why buy fast primes and use them stopped down :
In general, a 1.4 lens will be a better lens at 2.0 than a 2.0 lens at 2.0.
Why not use them stopped down? I know that sounds flippant, but there truly is no problem having headroom and not using it. As for the f/1.4 lens being better at f/2 than a f/2 lens at f/2...not always true. In fact, I don't even know that it is generally true. That may be why all of my "fast" lenses are f/1.7 or slower.

To the OP...

Thanks for doing this quick comparison. My comments:
  • I don't see the CA on the A*85, but if you say its there, I believe you. The second set of images...really nice...In fact, all of the Pentax 85s are really great.
  • I really like...want...need...a Pancolar 80/1.8
  • The Meyer...sorry, but just a little too dreamy for my taste
  • The FA 77/1.8...the results are what I have come to expect from this lens...worth every penny and compact to boot. 'Nuff said

Steve

Last edited by stevebrot; 09-30-2009 at 12:08 AM. Reason: Fixed bad math...
09-30-2009, 12:07 AM   #48
Veteran Member
Asahiflex's Avatar

Join Date: Jan 2008
Location: Netherlands
Photos: Gallery
Posts: 2,754
Original Poster
There definitely is CA in the A* shots. Just have a look inside the right eye of the mask photo. You'll see the blue shine there. Also, I made some pack shots a while back and the CA is clearly visible. This one was at f/6.3 (warning: this is a full-res image from my K-7: http://i385.photobucket.com/albums/oo293/spotmatic/KomuraBox-01.jpg). Look at the left side and you'll see it on the side of the box.

Regarding the Meyer: it's an uncoated pre-war lens, so I'm not surprised at all. With a little PP (added contrast) I can make it look as good as the other lenses.

Some good news: the 83mm f/1.9 is just in! Quite a nice lens with its 20 (or so) diaphragm blades. It's smaller than I thought however, it fits easily into a Macro-Takumar 4/50 lens case.

@Douglas_of_Sweden: I think you meant to say "Komura" instead of "Pancolar". The Pancolar belongs to the best in the bunch but the Komura is indeed soft at wide open aperture because of its old Ernostar design (early 20th century). However, after a little stopping down (to f/2.8 or just past f/2.8) things get considerably better. The Komura has great colors.













And it gets a 10 for looks

09-30-2009, 02:19 AM   #49
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,416
QuoteOriginally posted by Asahiflex Quote
There definitely is CA in the A* shots. Just have a look inside the right eye of the mask photo. You'll see the blue shine there. Also, I made some pack shots a while back and the CA is clearly visible. This one was at f/6.3 (warning: this is a full-res image from my K-7: http://i385.photobucket.com/albums/oo293/spotmatic/KomuraBox-01.jpg). Look at the left side and you'll see it on the side of the box...
Ok...I see what you are talking about on the mask image (blue fringe on left edge of right eye opening). Compared to the results from the other lenses, it definitely is distracting. I also do see some blue/yellow CA on the left side of the Komura box and on the adjacent white lettering. Not horrible, but probably enough to compromise sharpness for some subjects. This can be corrected in PP, but I can understand the expectation that this step should not be needed for a lens at this price point.

My vote still goes with the FA 77 Limited followed closely by the Pancolar and M 85. The A* 85 is nice, but I agree that the value point is not there.

Steve

(Ironically, the 77 Limited, while well-corrected against lateral CA, is prone to PF at times...my copy included. Perfection is always a step away!)

09-30-2009, 04:00 AM   #50
Veteran Member
rparmar's Avatar

Join Date: Jan 2008
Photos: Gallery
Posts: 8,783
QuoteOriginally posted by Douglas_of_Sweden Quote
The A*85 and the DA77ltd produce very similar pictures, and they should since they have the same optical solution, with the difference that wide open the 1.4 lens has a thinner DOF and hence less of the plants etc in focus. There is probably two things going on here at the same time: the A*85/1.4 really goes quite soft wide open, then it sharpens up rapidly when you close down (which is confirmed by the later portrait shots). In addition, the thinner DOF enhance this impression. The softness wide open is probably why Pentax limited the limited 77mm to f1.8 since that optical solution is not ideal if you go further. My guess is that at the f2 shoot out, the difference will be much smaller, the A* may even surpass the 77 in sharpness.
Great summary. I agree with your assessment based on other photos I have seen. I also second your call for a Limited lens based on the 85mm. That would be sweet!
09-30-2009, 05:00 AM   #51
Pentaxian
Class A's Avatar

Join Date: Aug 2008
Location: Wellington, New Zealand
Posts: 9,193
QuoteOriginally posted by Asahiflex Quote
There definitely is CA in the A* shots. Just have a look inside the right eye of the mask photo. You'll see the blue shine there.
True, but note that the Pentax 85/2.0 got CA as well, and (in green) the Pancolar and the Takumars.

Note that some of these colour aberrations could show up worse the more something is not in focus. That's were a non-scientific test shows its limits. From your test you cannot conclude that the A* 85/1.4 has worse CA than other lenses. It may have, but since your focus is not always on the same spot, you cannot deduct it from your images.

I understand that you would wish the A* 85 had less CA but overall I'd still rate it my favourite.

BTW, the "CA" might be out-of-focus colour aberrations. Strictly speaking CA is only defined for in-focus areas. It seems like "out-of-focus colour aberrations" as there is only minimal blue/yellow fringing between the black and white borders of your box shot, with the highly visible blue fringing being confined to edges which are already a bit out of focus.

Nice focusing, BTW. I guess you are using a split-prism screen?

Last edited by Class A; 09-30-2009 at 05:08 AM.
09-30-2009, 06:01 AM   #52
Veteran Member
Asahiflex's Avatar

Join Date: Jan 2008
Location: Netherlands
Photos: Gallery
Posts: 2,754
Original Poster
QuoteOriginally posted by Class A Quote
True, but note that the Pentax 85/2.0 got CA as well, and (in green) the Pancolar and the Takumars.

Note that some of these colour aberrations could show up worse the more something is not in focus. That's were a non-scientific test shows its limits. From your test you cannot conclude that the A* 85/1.4 has worse CA than other lenses. It may have, but since your focus is not always on the same spot, you cannot deduct it from your images.
You're completely right, hence the "pointless" in the thread's title. But I'm getting extremely good ideas from all of the replies here, including yours. So I hope the definitive "test" will also really be "definitive"

QuoteQuote:
I understand that you would wish the A* 85 had less CA but overall I'd still rate it my favourite.
It still isn't my favorite, but that may change of course.

QuoteQuote:
BTW, the "CA" might be out-of-focus colour aberrations. Strictly speaking CA is only defined for in-focus areas. It seems like "out-of-focus colour aberrations" as there is only minimal blue/yellow fringing between the black and white borders of your box shot, with the highly visible blue fringing being confined to edges which are already a bit out of focus.
I've always connected the blue "CA" to high-contrast transitions, such as a black border to a white background. Maybe I'm wrong though. I should have shot the box with another lens too just to be sure. But fact is - I experience more blue CA with the A* 85/1.4. I'm not referring to the CA in OOF areas - I expect this because none of the lenses are APO ones.

The M85/2 also shows this blue CA as can be seen here (in the rose for instance):



QuoteQuote:
Nice focusing, BTW. I guess you are using a split-prism screen?
No, sometimes I use the Live View of the K-7. With the last set of portraits I just used the focusing screen. With some experience I'm now able to get perfect focus with the stock ground glass screen (it's actually easier to focus than the K10D and the K20D).
09-30-2009, 09:52 AM   #53
Veteran Member
glasbak's Avatar

Join Date: Apr 2009
Location: Netherlands
Posts: 346
QuoteOriginally posted by stevebrot Quote
As for the f/1.4 lens being better at f/2 than a f/2 lens at f/2...not always true. In fact, I don't even know that it is generally true. That may be why all of my "fast" lenses are f/1.7 or slower.

Steve
Can you give an example of a 1.4 lens, which is still 1.4 in the corner of a 24x36 image ?
Stopped down to 2.0, the vignetting is already much less.
Almost the same for 1.7/2.0 lenses, you have to stop them down to 2.8 or so to get an even illuminated image.
And that already proves my point.
Most other aberrations decrease also significantlly when stopping down from 1.4 to 2.0.
I have never seen photographic optics which get worse when stopping down (except where diffraction spoils the picture)
In theory, a perfect lens has the best performance at the largest aperture though, but who has that photographic lens ?

QuoteOriginally posted by Asahiflex:
The Komura has great colors.
I see lots of similar comments, 'a lens has great colors'.
How can a clear peace of glass have any effect on the color of the image (apart from chromatic aberration) ?
Exposure variation, environmental light, white balans, sensor, monitor (+ calibration), printout (+calibration) etc. determine the color, not the lens.

George

09-30-2009, 11:29 AM   #54
Veteran Member




Join Date: Mar 2008
Location: Nowhere, Sweden
Photos: Gallery
Posts: 654
QuoteOriginally posted by glasbak Quote
I see lots of similar comments, 'a lens has great colors'.
How can a clear peace of glass have any effect on the color of the image (apart from chromatic aberration) ?
Exposure variation, environmental light, white balans, sensor, monitor (+ calibration), printout (+calibration) etc. determine the color, not the lens.

George
Why not? Consider your own statement "a clear piece of glass" and then rethink what a lens is.
09-30-2009, 12:31 PM   #55
Site Supporter




Join Date: Jan 2007
Location: Upstate New York, US
Photos: Albums
Posts: 223
QuoteOriginally posted by glasbak Quote
Can you give an example of a 1.4 lens, which is still 1.4 in the corner of a 24x36 image ?
Stopped down to 2.0, the vignetting is already much less.
Almost the same for 1.7/2.0 lenses, you have to stop them down to 2.8 or so to get an even illuminated image.
And that already proves my point.
Most other aberrations decrease also significantly when stopping down from 1.4 to 2.0.
I have never seen photographic optics which get worse when stopping down (except where diffraction spoils the picture)
In theory, a perfect lens has the best performance at the largest aperture though, but who has that photographic lens ?
I think you are generalizing too much here. Vignetting is probably the area where this is the most true (because it's usually related to the size of the piece of glass on the end of the lens), but even more vignetting for a slower lens at max aperture compared to a faster one stopped down is not guaranteed. Sharpness, contrast, and color being better on the faster lens stopped down to the max of the slower lens are far from guaranteed.

In lenses of similar quality sharpness will usually be better, but that's as far as I would go. As an example where even that is not generally considered true, look at the Pentax F 50 1:1.7 compared to various Pentax 50 1:1.4 lenses. Most people say that the f1.7 lens is sharper at f1.7 than the f1.4 lenses are at f1.7. This may be the exception to the rule, but it shows that you can't just assume that the faster lens will always be sharper at the max aperture of the slower lens.


QuoteQuote:
I see lots of similar comments, 'a lens has great colors'.
How can a clear peace of glass have any effect on the color of the image (apart from chromatic aberration) ?
Exposure variation, environmental light, white balans, sensor, monitor (+ calibration), printout (+calibration) etc. determine the color, not the lens.

George
I guess you'd have to ask the manufacturers why they all seem to have a different definition of the word "clear" . Seriously, lenses have a definite effect on the color of the resulting photos. You'll see people mention often that a certain manufacturer's lenses tend to have a warmer or colder rendering than the lenses of another manufacturer, and this is true. If you keep all the other factors the same, and merely switch lenses, you will see differences in color rendering. Auto white balance tends to hide this to some extent, but it is definitely there. The glass that lens makers use isn't perfectly clear, and I'm not sure I'd want it to be. This is one of the differences that gives different lenses, and their resulting photographs, distinctive character.
09-30-2009, 01:18 PM   #56
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,353
QuoteOriginally posted by glasbak Quote

I see lots of similar comments, 'a lens has great colors'.
How can a clear peace of glass have any effect on the color of the image (apart from chromatic aberration) ?
Exposure variation, environmental light, white balans, sensor, monitor (+ calibration), printout (+calibration) etc. determine the color, not the lens.

George
Because glass are not so clear as you believe and light are a bit more complex.
Different colors (different wavelengths) have different refractive index. This is what cause Chromatic Abberration when different colors have different focus points, but it also do other things with the difference between what enters the lens and what leaves it in the other end.
Different glass mixtures (adding trace compounds to the glass is one way the manufacturers try to minimize unwanted effects and optimise the output of the lens) also have different effects on light of different wavelength (color).
The coating...well the way I understand it...the reason why we need multi-coating or even super-multi-coating is because a one layer coating, while it can get rid of a lot of the reflections, it do that to different degree for different colors, so they started to combine severall layers of coatings optimised for different colors until we had the SMC, RMC etc. But this never work perfectly and each manufacturer has a bit different multi-coating methods and this gives a different final effect on how the colors comes out.
So lens design, glass quality and coating properties all influence the color character you get from a lens. Long before sensor/film does.
09-30-2009, 01:40 PM   #57
Site Supporter
Douglas_of_Sweden's Avatar

Join Date: Apr 2008
Location: Stockholm
Photos: Gallery
Posts: 3,353
Asahiflex, just a short question...regarding the older lenses with less coating. Did you use a hood on them?
09-30-2009, 02:10 PM   #58
Veteran Member
georgweb's Avatar

Join Date: Apr 2008
Location: Berlin, Germany
Photos: Gallery
Posts: 1,381
George/glasbak,

here's an interesting read on color fidelity in Minolta's 70ies/80ies lenses.

It also highlights Leica's quest for microcontrast (MTF>60) and that Zeiss did quite the opposite (MTF<30 = the usual 'test'-MTF).

It dawns on me why Zeiss developped genuine soft filters - the "Über-Kontrast" is not "the best" in every given field of photography.
In that regard I like Peter's portraits from the Komura more than those from the Pentax superstar (which obviously is a stellar lens).

Peter, thanks for putting so much work in this, I have great joy in watching every photo of yours from all those lenses I might never have!

Best, Georg (the other)

Last edited by georgweb; 09-30-2009 at 03:19 PM.
09-30-2009, 02:36 PM   #59
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,416
QuoteOriginally posted by Asahiflex Quote
The M85/2 also shows this blue CA as can be seen here (in the rose for instance):


I think that what you are calling "blue CA" is what many of us would call "Purple Fringing" (PF). There is lots of it in the above photo. I have never read a really good explanation as for what causes it, but it is not CA (lateral or axial) in the classic sense. Current thinking is that it is artifact related to the physical structure of the digital sensor. Some lenses are more prone to generating PF as are some sensors. Probably the best evidence that PF is not strictly a lens issue is the fact that it is entirely absent from film images. CA, on the other hand, is easily demonstrated on film.

Steve
09-30-2009, 02:46 PM   #60
Veteran Member
Asahiflex's Avatar

Join Date: Jan 2008
Location: Netherlands
Photos: Gallery
Posts: 2,754
Original Poster
QuoteOriginally posted by Douglas_of_Sweden Quote
Asahiflex, just a short question...regarding the older lenses with less coating. Did you use a hood on them?
Yes, in fact the 7,5cm Primoplan has the (metal) hood attached all the time.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
k-mount, pentax lens, portrait, slr lens, subject, test
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
People Portrait Exercise Jun 19 danielchtong Post Your Photos! 1 06-27-2010 06:58 AM
For Sale - Sold: EX+++ Canon EF USM 100mm f/2.0 Fast Portrait Lens, Worldwide Shipping wallyb Sold Items 1 12-01-2009 11:23 AM
For Sale - Sold: Minolta Rokkor 85mm f/1.7 Fast Portrait Lens converted to M42 Mount wallyb Sold Items 6 02-26-2009 10:55 AM
Examples from long teles which don't include birds? Jasvox Pentax SLR Lens Discussion 49 01-29-2009 11:10 PM
Who says Pentax don't have long teles? 2 x 780mm lens coming Katsura Pentax SLR Lens Discussion 3 09-26-2007 10:38 AM



All times are GMT -7. The time now is 06:03 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top