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10-08-2019, 07:07 AM   #7441
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It is complicated. Actually while Pentax 50/1.7 lenses are great at f5.6 it is the only aperture at which they are tad worse than my other vintage lens- Rikenon 50/2. At f4 and f8 they are clearly better (not by much of course).


Last edited by Piotrek K; 10-08-2019 at 08:59 AM.
10-08-2019, 08:06 AM - 1 Like   #7442
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M100/2.8. Silver Efex Pro "Antique plate" preset.


Lion's head par Kris Lockyear, on ipernity
10-08-2019, 02:50 PM   #7443
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QuoteOriginally posted by iheiramo Quote
That's why I used term, usually, in my sentence. I do like to use my M50/1.7 between f4 and f5.6 and even wide open, but according to same source it, indeed, is sharpest at f8.
I have no experience to comment behaviour of other series, but with M stopping down does make them sharper. Of course there are other values than sharpness in photography. Since getting K1ii I've shot quite a lot wide open with my M's, as with FF the results are sharp enough.
These tests are probably a weighted average of the center and corners, but the tester doesn't really say. So what are those lines? Corners only?
Also, they are quite old and were made on film. I still look at them from time to time but I wouldn't expect them to be the supreme authority on the sharpness of a lens, especially since I've seen other tests where the SMC-A 50 1.7 was sharpest overall at f5.6, not f8 like on that test.
10-08-2019, 10:52 PM   #7444
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QuoteOriginally posted by ChristianRock Quote
Also, they are quite old and were made on film. I still look at them from time to time but I wouldn't expect them to be the supreme authority on the sharpness of a lens, especially since I've seen other tests where the SMC-A 50 1.7 was sharpest overall at f5.6, not f8 like on that test.
I'm really not that much a test person, so can't comment on how well that test is done and how correct it is. I only know of it because it was linked to me when I was protecting M85 being worth its price and had dig it up from old posts

10-09-2019, 12:19 AM - 1 Like   #7445
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QuoteOriginally posted by Benz3ne Quote
Agreed, but with my A-50/1.7. Heck, it's even nice around f/2.8.
Same goes for the M-50/1.4. It's wonderfully sharp at f/2.8 and /4 is tack-sharp. Of course, this continues through /5.6 and towards /8.
Same here, plus I'm not always interested in absolute sharpness (with the M-50/1.4 of my K135/2.5 I also enjoy the bokeh). I often find myself stopping down to make focussing easier, even with CIF.
10-09-2019, 03:01 AM - 1 Like   #7446
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Pentax MX, SMC Pentax-M 100mm f/2.8, expired Kodak BW400CN film @ 200. (Cross-posted with the BW film images thread.)


Dahlias par Kris Lockyear, on ipernity
10-09-2019, 03:18 AM   #7447
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QuoteOriginally posted by womble Quote
Pentax MX, SMC Pentax-M 100mm f/2.8, expired Kodak BW400CN film @ 200. (Cross-posted with the BW film images thread.)


Dahlias par Kris Lockyear, on ipernity

The shot is nice, but it doesn't show on PF. The link to Ipernity works. To get the shot visible you need something like BBCode on Flickr or direct address of jpg image. I believe I've seen shot from Ipernity here before, so it can be done

Edit: At least I cannot see the image. Don't know if it's visible for others.

10-09-2019, 03:28 AM   #7448
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QuoteOriginally posted by iheiramo Quote
The shot is nice, but it doesn't show on PF. The link to Ipernity works. To get the shot visible you need something like BBCode on Flickr or direct address of jpg image. I believe I've seen shot from Ipernity here before, so it can be done

Edit: At least I cannot see the image. Don't know if it's visible for others.
I've been using BB code from Ipernity for all my images on PF. Clearly it usually works judging by the likes the images have got. Something odd is going on. I noticed that someone else's "selfie" shot showed when I first looked at it, then didn't later. And they aren't using Ipernity.

K.
10-09-2019, 03:29 AM   #7449
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QuoteOriginally posted by iheiramo Quote
The shot is nice, but it doesn't show on PF. The link to Ipernity works. To get the shot visible you need something like BBCode on Flickr or direct address of jpg image. I believe I've seen shot from Ipernity here before, so it can be done

Edit: At least I cannot see the image. Don't know if it's visible for others.
I can see it. The problem is with your settings and you're not the first to have it. I experienced it with one user's posts a while back and had to go to my settings and turn something off and back on again, unfortunately I don't remember which setting it was.

Regarding the ongoing debate, there are very few lenses which don't have a sweet spot (assuming this means optimum sharpness) around f/8, though with modern digital sensors I believe that with sharp lenses diffraction has a small impact at f/8 resulting in f/5.6 being the sweet spot. But any lens that doesn't produce good, sharp images at f/8 is a very bad lens.

Personally, it's hard to think of many lenses which don't perform very well at f/8. The exceptions that come to mind are super- and ultrawide lenses such as the Sigma 10-20mm f/3.5, DA 15mm limited and Cosina 19-35mm, which all benefit from stopping down to f/11 to maximise corner sharpness, though this is possibly at some expense of centre sharpness due to afore-mentioned diffraction.

I don't worry much about these things - I know which apertures I'm happy to use my lenses at depending on the results I want. For example any of the 50/55mm f/1.7 or 1.8s will be very sharp by f/2.8. This isn't based on them being in the M, or any other, series, it's just a question of knowing your lenses.
10-09-2019, 03:34 AM   #7450
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Visibility problem: see gofour3's post (#19676) in the film images thread, cf. dsmithhfx's reply (#19677).

Perhaps the fora have had a code upgrade and we need to adjust settings as Jonathan suggests? It is not an Ipernity problem.
10-09-2019, 03:49 AM   #7451
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QuoteOriginally posted by Jonathan Mac Quote
I can see it. The problem is with your settings and you're not the first to have it.
OK. I look around the settings, if it doesn't disappear by itself in couple of days. I noticed it only with last two posts from Womble.
10-09-2019, 04:33 AM   #7452
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QuoteOriginally posted by womble Quote
Perhaps the fora have had a code upgrade and we need to adjust settings as Jonathan suggests? It is not an Ipernity problem.
Thanks for the comments. I'll look into it.
10-09-2019, 04:34 AM - 1 Like   #7453
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October Single In Challenge 2019 with K1ii & M100/4

9th

This week weather was sopposed to be bad, but today at lunch time... Just about as good as October can get. One day I get back to close-ups and macros, but today I continue stitch work. I also got good autumn colors, but I just had to go with one which has sea in it.

K1ii M100/4 ISO100 f4 1/750 Brenizer method from 21 shots:
10-09-2019, 06:06 AM   #7454
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QuoteOriginally posted by iheiramo Quote
I'm really not that much a test person, so can't comment on how well that test is done and how correct it is. I only know of it because it was linked to me when I was protecting M85 being worth its price and had dig it up from old posts
I think the test is fine, I recommend it sometimes because there aren't a whole lot of tests made with lenses from that era that are available on the internet. Generally, I think they give a good idea of how good a lens is. But they're old tests and we don't really know how they were done, so I'd take them as a guideline only and work on each lens to see how that sample stacks up - if we have lens sample variation today, back then there was probably even more!

Sometimes even magazine tests from the 80s and 90s aren't reliable - for example I've seen a magazine test that ranked the SMC-A 70-210mm f4 as a pretty bad lens, not very sharp at all. Now I think we know it's one of the best zooms from that era and it gets used quite a lot on digital Pentax DSLRs.
10-09-2019, 08:59 AM   #7455
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QuoteOriginally posted by ChristianRock Quote
I think the test is fine, I recommend it sometimes because there aren't a whole lot of tests made with lenses from that era that are available on the internet. Generally, I think they give a good idea of how good a lens is. But they're old tests and we don't really know how they were done, so I'd take them as a guideline only and work on each lens to see how that sample stacks up - if we have lens sample variation today, back then there was probably even more!

(...).
Well for good OEM lenses (like Pentax - M) I tend to believe that sample variation was much less thanrith today's lenses. But after 40 -, 50-years it is clear it is no more the case.
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