The M Club!

Piotrek K · 10-08-2019, 07:07 AM

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.

womble · 10-08-2019, 08:06 AM - **1 Like**

M100/2.8. Silver Efex Pro "Antique plate" preset.

Lion's head par Kris Lockyear, on ipernity

ChristianRock · 10-08-2019, 02:50 PM

Originally posted by iheiramo

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.

**iheiramo** · 10-08-2019, 10:52 PM

Originally posted by ChristianRock

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

HoutHans · 10-09-2019, 12:19 AM - **1 Like**

Originally posted by Benz3ne

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.

womble · 10-09-2019, 03:01 AM - **1 Like**

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

**iheiramo** · 10-09-2019, 03:18 AM

Originally posted by womble

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.

womble · 10-09-2019, 03:28 AM

Originally posted by iheiramo

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.

Jonathan Mac · 10-09-2019, 03:29 AM

Originally posted by iheiramo

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.

womble · 10-09-2019, 03:34 AM

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.

**iheiramo** · 10-09-2019, 03:49 AM

Originally posted by Jonathan Mac

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.

**iheiramo** · 10-09-2019, 04:33 AM

Originally posted by womble

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.

**iheiramo** · 10-09-2019, 04:34 AM - **1 Like**

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:

ChristianRock · 10-09-2019, 06:06 AM

Originally posted by iheiramo

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.

Piotrek K · 10-09-2019, 08:59 AM

Originally posted by ChristianRock

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.

10-09-2019, 04:34 AM - 1 Like	#7453
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	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:

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10-08-2019, 07:07 AM	#7441
Piotrek K Pentaxian Join Date: Dec 2012 Photos: Gallery Posts: 1,384	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
womble Pentaxian Join Date: Apr 2010 Location: Hertfordshire Photos: Gallery Posts: 4,324	M100/2.8. Silver Efex Pro "Antique plate" preset. Lion's head par Kris Lockyear, on ipernity

10-08-2019, 02:50 PM	#7443
ChristianRock Pentaxian Join Date: Jul 2013 Location: People's Republic of America Photos: Gallery \| Albums Posts: 9,910	Originally posted by iheiramo 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
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by ChristianRock 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
HoutHans Pentaxian Join Date: Aug 2016 Location: Appingedam Photos: Gallery Posts: 3,119	Originally posted by Benz3ne 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
womble Pentaxian Join Date: Apr 2010 Location: Hertfordshire Photos: Gallery Posts: 4,324	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
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by womble 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
womble Pentaxian Join Date: Apr 2010 Location: Hertfordshire Photos: Gallery Posts: 4,324	Originally posted by iheiramo 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
Jonathan Mac Pentaxian Join Date: Apr 2009 Location: Madrid, Spain Posts: 10,897	Originally posted by iheiramo 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
womble Pentaxian Join Date: Apr 2010 Location: Hertfordshire Photos: Gallery Posts: 4,324	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
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by Jonathan Mac 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
iheiramo Unoriginal Poster Join Date: Nov 2016 Location: Espoo Photos: Albums Posts: 3,182	Originally posted by womble 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, 06:06 AM	#7454
ChristianRock Pentaxian Join Date: Jul 2013 Location: People's Republic of America Photos: Gallery \| Albums Posts: 9,910	Originally posted by iheiramo 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
Piotrek K Pentaxian Join Date: Dec 2012 Photos: Gallery Posts: 1,384	Originally posted by ChristianRock 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.