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Forum: Welcomes and Introductions 02-26-2017, 06:11 PM  
MU43 with vintage Pentax Glass
Posted By Stirling Bartholomew
Replies: 11
Views: 1,043
I know this doesn't matter but I did quick living room shot focusing on the left hand corner and did a comparison of Zuiko 14-54mm at 35mm, with 1/3 stop increments from f3.2-f5.6 and then the SMC 35mm f3.5 same setup with half stop increments when possible. The wide open f3.2 Zuiko shot was better than the best I could get from SMC 35MM at f6.3 or f8. Here are screen captures of images in Lightroom at a ratio of 2:1. First Zuiko 14-54mm at 35mm at F4. Next is the SMC 35mm at f6.3 which was best of the lot. (Not much change from f5.6-f8, however f6.3 is a lot better than f3.5. You can see that plainly in field tests. It isn't the OOF that bothers me, its the qulaity of OFF, the bokeh is ugly in a number of my field tests. It isn't far enough OOF, just enough to look jagged. These screen shots at 2:1 make bokeh look smoother than what I was bringing home in the field tests. I would post field tests but they subject matter wasn't thrilling and it would waste storage.

The third shot is the SMC 35mm F3.5 wide open at f3.5.
Forum: Welcomes and Introductions 02-25-2017, 03:23 PM  
MU43 with vintage Pentax Glass
Posted By Stirling Bartholomew
Replies: 11
Views: 1,043
I am really not assuming that my lens is typical. The resolution charts were small and not really readable where I saw them posted. It looked like the fall off in resolution from center to 2/3 was pretty dramatic but if people are getting good shots on 24mp FX cameras with this lens I am willing to accept the fact that damage to lens might not be visible. Under extreme heat the surfaces between the lens elements might undergo irreversible changes which would throw everything out of alignment without it being visible looking into the glass.

What defies imagination is why I have a Pentax-M 85mm f2 lens with visible mould in dozen places on internal surfaces and find it quite usable and other hand have a spotless pristine lens SMC 35mm f3.5 which the more I look at it with strong light at various angles I am convinced it has no internal defects, not even a tiny dust spots. This perfectly spotless lens is not behaving as it should. I can see using the 10x focus enlargement in the Oly EM-5 that the whole image is soft and doesn't improve much stopping down. Most of my field test shots look decent at 1:2 in Lightroom. It is only at 1:1 you see the difference between the different lenses.

I like to experiment with lenses that have faults like flare and CAs to see what sort atmospheric affect can be gained. Recently read the autobiography of Sally Mann titled "Hold Still" which got started on playing around with all the old lenses again.

Thank you for the replies.
Forum: Welcomes and Introductions 02-25-2017, 08:52 AM  
MU43 with vintage Pentax Glass
Posted By Stirling Bartholomew
Replies: 11
Views: 1,043
I agree. The general pattern of the results are typical of many lenses. Its like seeing a radial gradient in Lightroom. The center out performs the edges by a significant amount. In the case of the test i saw the drop between the center and the mid-postion was radical so that would mirror what you would seen on 4/3 crop. Doesn't really matter how it performs on other sensors. I am using the same adapter for three other lenses and it works fine. This was a topic for introduction to the forum not some big problem that needs to be solved. My tests on the other vintage lenses produced results you would expect. The pentax-m 200mm f4 isn't steller but usable. The ST 150mm f4 is better than the 200mm. The ST 55mm f1.8 and Pentax M-55m f1.7 are both very good, with the later showing sligt edge over the older at f2. The Pentax M-50mm F2 isn't in the same ball park so it ghathes dust. I keep in permanently mounted on a pentax K1000 body which will probably never be used.

Thanks for all the replies.
Forum: Welcomes and Introductions 02-24-2017, 11:09 AM  
MU43 with vintage Pentax Glass
Posted By Stirling Bartholomew
Replies: 11
Views: 1,043
Thank you for the replies. This is a friendly forum.

I took the SMC 35mm F3.5 for another field test. I find shooting charts in my living room tedious and I have already done that. Look at what I shot yesterday I can see how someone shooting film and printing 8x10s or even 11x14s might find this lens usable. But pixel peeping and comparing the results to the Oly E1 "kit lens" aka Zuiko 14-54mm f2.8-3.5 the digital zoom lens at 35mm is better at f4 than the Pentax at any aperture. This shouldn't surprise anyone. The digital lens was designed for digital sensors which put demands on a lens somewhat different than film.

I do a lot of shooting of flat surfaces at 90 degrees, the brick wall shot, so any kind of field curvature would be notable at wide apertures. But f4-5.6 on 4/3 sensor equal to two stops smaller in 35mm film. So DOF isn't the issue. I also specifically tested using charts for field curvature and it turns out the corners are soft even when you focus on the corner. So perhaps the lens is damaged from heat but not vioiably. It was hauled all over Israel for 8 months in a backpack which was left sitting in the sun.

I would like a to use a smaller lens than Zuiko 14-54mm f2.8-3.5 for street shooting. But it is my best option under the circumstances. I had a 28mm prime with a Pentax K mount but it was some off brand and optically it was worthless. SMC 35mm F3.5 delivers decent medium size images. But when you shooing complex and high contrast texture the gradual softening toward the corners isn't acceptable.

I saw one review of the SMC 35mm F3.5 which had resolution charts showing three zones: middle 2/3 and extreme corner resolutions. The charts mirrored my test results. The extream corners were soft to marginally acceptable at all apertures. Again, I didn't run the test for these charts and know nothing about how they were done. My own living room tests were done at a distance of 3 meters shooting at five US AIRFORCE charts vintave 1951. After running these tests my experience in the field shooting side by side with the Zuiko 14-54mm resulted in retireing the old prime.
Forum: Welcomes and Introductions 02-23-2017, 01:42 PM  
MU43 with vintage Pentax Glass
Posted By Stirling Bartholomew
Replies: 11
Views: 1,043
I started mounting old pentax lenses on a Pana G2 I picked up when they were dumping them at steep discount in 2011. I had the Pentax S1a that I gave my father for XMas in the early 70s. So I mounted 55mm ST f1.8 on the G2 and had lots of fun. I also had a vivatar 135mm f3.5 in m42 mount. Both lenses were tolerable at 12mp G2. The Vivatar didn't improve with stopping down. At F4 it was as gook as it was going to get. The ST55mm f1.8 wide open was soft and dreamy which I liked for some applications. At F2 it cut CA's some and helped contrast and from 2.9-5.6 in improved.

In 2013 an old friend gave me his Pentax gear. All of it. Two bodies seven lenses. Most of it was late 1970s gear and had been toted all over europe and middle east under unfavorable circumstances. I found this fourm when I started looking for comments on lens performance for the lens in his kit. I ended up keeping all but lens which was not a pentax and was worthless for digital. I am now shooting with them on an OLY E-M5 MK1. Most of reviews I found on the lenses seemed somewhat weighted toward optimism on issue of resolution. The reviewers don't always tell you what body they were testing the lens with and this makes for diffiuclties since. One I read which really supprised me was a fellow who had mounted a SMC 35mm F3.5 on a Sony A7 and reported that it worked well. The lenses I have tested include Pentax-M 200 F4, Pentax-M 85mm F2, Pentax-M 50 F2, Pentax-M 55mm F1.7, F4, ST 150mm f4, SMC 35mm F3.5. The last in the series is the most problematic since I was unable to get any kind of resoution in corners even at f8. The lens is in pristine conditon, looks brand new. No dust, no mould, flawless glass. On MU43 cameras it is soft at f8-f3.5 getter softer as you open up.

Perhaps something happend to this looks like new lens while it was toted through the Sinai in 1979. The other lenses which were along for the ride work as expected. The Pentax-M 85mm F2 has spots of mould on the internal surfaces but it doesn't cause any problems on 4/3 sensor. It is soft with hugh CA's wide open but from f2.8 to 5.6 or even f8 it is very usable. I mention it since it is most damaged lens in the lot and the SMC 35mm F3.5 is the most undammage, virtually mint condtion lens.

Anyway,

I did film photograpy in 1970, worked for studios, labs, freelance. From 1980-2005 didn't own a camera. Been shooting 4/3 cameras since 2006.

Stirling Bartholomew
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