[osv]

Well, such claims are just hopelessly misleading. I have looked at some of Norman Koren's speculations about film and resolution, and most of the stuff is really outdated. I shoot Fuji Provia 100F in 135 format, and with the Minolta Dimage Scan Elite 5400 scanner, I am sure I could extract the equivalent to 24mp from a well exposed Provia 100F slide, taken with the best lenses, tripod and cable release. A drum scan of the same slide would possibly result in an even better digital version.

norman koren is a scientist, not some internet flack... if you had actually read the article, you would have seen him debating with michael reichmann, over what amounts to the same conclusion: "Michael Reichmann's article, Ultimate Shoot-out, compares his 11 Megapixel EOS-1Ds to the medium format Pentax 67II. Although I agree with his conclusion that the EOS-1Ds has better overall image quality-- I'd buy one today if I could comfortably afford it-- I have to dispute one important detail: which camera has the higher resoluton. It's the Pentax. You can see it on the enlargements of the windows in the middle of the page, the second set of images under The Print Evaluation. A vertical line on the wall on the right is visible in the Pentax image but not in the EOS-1Ds image. Should this change Michael's essential conculsions? No. This thin line represents response at a very high spatial frequency that would have little effect on the appearance of a 13x19 inch image. It would be visible on a 24x30 inch image, but the 1Ds still has superior image quality due to the absence of grain-- see the discussion on Shannon channel capacity and image quality."

see the part about "compares his 11 Megapixel EOS-1Ds to the medium format Pentax 67II"... how can you claim that film is better than digital, when they can't quite agree over 11mp ff vs. mf film

fyi... the canon EOS-1Ds was released in 2002...

For anyone interested in a scientific and thorough discussion about film resolution, including the Adox CMS 20 film mentioned above, you should check out this article by Tim Parkin (from On Landscape Magazine):
https://www.onlandscape.co.uk/2014/12/36-megapixels-vs-6x7-velvia/

pure gibberish... that guy is a moron, and he doesn't know how to use a camera, look at the d800 photo, why is it soft, and why is there a bunch of blocky artifacting around the "nikon" text?

and once again, it's somebody comparing mf film to ff digital... if film is so good, why is no one comparing ff film vs. ff digital?

[r0ckstarr]

Maybe the guys from Finding Bigfoot should search for a copy of that lens instead. They might even find one...

I was wondering if anyone would catch it.

[osv]

Easy...the 28mm lenses I own are all at their infinity stop at that distance as reckoned by the split image finders on my film cameras.*

the ovf in film cameras doesn't begin to compare to the accuracy of full magnification in a good evf... it's so good that i can see diffraction at f/10.

there is no such thing as an "infinity stop" in camera lenses, that's a film construct that's used to cover up for the fact that you can't truly focus an ovf at long distances: When hyperfocal distance focusing is not good enough

many modern camera lenses, for example, don't have hard stops.

[stevebrot]

there is no such thing as an "infinity stop" in camera lenses

Ummmm...there is if the focus ring does not go any further.

This is not a question of superior vs. inferior vs. optical vs. electronic viewfinders (even excellent, state-of-the-art EVF). I actually did the exercise this afternoon and started with my S-M-C Tak 28/3.5.* With my copy (second version, the small one) at 100 yards distance it is not within the mechanical tolerances of the lens to do fine focus. I then switched cameras to magnified live view on the K-3 (e.g. high quality EVF at 100% the sensor resolution). Even a 1/2 degree of arc short of the hard stop has the plane of focus at 50 yards or closer. Now perhaps my ST 28/3.5 needs to be adjusted, but I had similar experience with both my Vivitar 28/2.8 CF (Komine) and Tamron 28/2.5 (02B).

I expected this result because, as is typical for that class of glass, the focus throw on all three lenses from infinity to 1m is only about 45 degrees of arc. The reason I went through the exercise was because you said you were able to nail focus both your K 28/3.5 and M28/3.5 at 100 yards with your A7RII. I then took a good look at your very excellent example linked above and sure enough, the "5610" is very nicely in focus as are most of the rows in the field and the power lines down by the beach. At f/8, this is what I would expect even if evaluated at full resolution from the A7RII.

Short answer? I am fully confident that I can "nail" focus at 100 yards with any of my 28mm lenses at f/8 with any of my film bodies or with the K-3 for that matter since the technique is the same.


Steve

* I don't have the K or M 28/3.5 and the S-M-C is the closet I could get from my shelf.

---

Last edited by stevebrot; 01-28-2016 at 09:03 PM.

[Dewman]

My copy of the K28/3.5 has no problems edge to edge on FF digital.

People must be careful saying a lens is no good - they're talking only about the performance along the bell curve of the one they own, not everyone else's.

Well said, my man! That's one of the reasons I take the lens reviews here on PF with a very large grain of salt! All it takes is for one person ( or 2) to have a bad experience with a lens and give it horrible scores and the overall rating drops through the floor. I tend to ask current posters their opinion of a lens I'm interested in, not someone who gave their opinion of it 7 or 8 years ago.

[osv]

The purpose of the lack of a hard infinity stop in AF lenses is to keep the AF mechanism from racking to a hard stop at the end of the focal throw and damaging the focusing motor, not because eliminating the stop gives you meaningfully better results at infinity.

i could see motor protection for in-body focus motors, but companies have been using hard infinity stops on af lenses for decades... the trend for modern lenses is focus-by-wire, the focus ring just spins endlessly.

"But where other lenses have helicoids that move focusing elements along grooved tracks, Sony FE lenses use electromagnets to move the focusing elements along a set of rails." LensRentals.com - Sony FE 35mm f/1.4 ZA Lens Teardown

that's right, no af motor at all... it's superior for af use, because it allows for very small back-and-forth focus movements, that are not impeded by stiction.

the complete lack of an infinity hard stop is a recent development in the history of af lenses for shooting stills, but it has been used on video cameras going back to the mid 90's, at least.

companies realize that there is no such thing as true infinity focus:

"For decades, the Canon FD and EF lenses have featured a variable infinity setting. Canon has two reasons for this:
Thermal expansion
Allowances for infrared photography
...Sony's rapidly expanding lens line features several approaches to the infinity-focus conundrum. Many of its lenses are devoid of focus markings, and the manual focus rings spin freely with no stops at all. Several of the company’s lenses feature soft-stops and the "L" marks, denoting a variable-infinity range. The owner's manuals claim that the "infinity position provides for some adjustment to compensate for focus shift caused by a change in temperature," before recommending that focus is verified through the viewfinder or live view modes.
...From a Tamron lens owner's manual: "The focusing ring rotates beyond the infinity position in order to properly focus to infinity under a variety of environmental conditions. When manually focusing, make sure the subject at infinity is sharp in the viewfinder."
etc...
Who Killed Infinity Focus? | explora

[fs999]

Soligor 20mm F2.8 C/D Wide-Auto of course...

On MZ-7

[pathdoc]

That's one of the reasons I take the lens reviews here on PF with a very large grain of salt! All it takes is for one person ( or 2) to have a bad experience with a lens and give it horrible scores and the overall rating drops through the floor.

Amen. The lens reviews are a good place to start, but you have to read the text and sometimes between the lines too; it's the only way to weed out the trolls, the malcontents ("Pentax is DOOMED!!!"/"Stop the full-frame now!"), and those who mean well but simply cannot give a coherent review.

[gofour3]

i'd like to see any film shooter on this forum back that claim up 28mm, 2' target, at 100 yards, post it up

As Steve mentioned you just move the infinity mark on the K28/3.5 to the red diamond mark and anything at 100 yards/meters will be in focus. Or if you want more foreground DOF you move the infinity mark to the aperture you are using on the distance scale.

Just curious what kind of adapter do you use on your Sony, for mounting Pentax K-Mount lenses? The adapter could be another reason you are getting less than ideal results with your K28/3.5, compared to what I can get using it on one of my Pentax K Series film bodies.

I'm assuming you are using older Pentax MF lenses on your Sony because you already owned them and the Sony 28mm lenses are very expensive? You'll always get better results with a lens if you use it on the camera it was designed for.

Phil.

[osv]

As Steve mentioned you just move the infinity mark on the K28/3.5 to the red diamond mark and anything at 100 yards/meters will be in focus. Or if you want more foreground DOF you move the infinity mark to the aperture you are using on the distance scale.

that works because there is room for slop with the dof at 28mm... but it's an imprecise guesswork technique, that's obsolete and unnecessary with mirrorless, and even with liveview in an lcd... the only reason for focusing like that is because people can't achieve accurate focus with an ovf.

Just curious what kind of adapter do you use on your Sony, for mounting Pentax K-Mount lenses? The adapter could be another reason you are getting less than ideal results with your K28/3.5, compared to what I can get using it on one of my Pentax K Series film bodies.

glassless adapters do not alter the path of light through the lens, so they have zero effect on pq... there is the possibility of a very small tilt factor, but tilt/shift lenses do not lower resolution, look at the canon 17mm/24mm tilt/shift lenses for example.

I'm assuming you are using older Pentax MF lenses on your Sony because you already owned them and the Sony 28mm lenses are very expensive? You'll always get better results with a lens if you use it on the camera it was designed for.

so why put a k28/3.5, that was designed for film, on a k3?

the things i'm talking about here will be difficult to understand for people who don't have experience with 36mp mirrorless... you all should try to understand, because this is how your lenses will look on the new pentax ff camera.

yes, i already had the old glass, but if you blow this photo up to 100%, you'll see why i'm not interested in new glass... it's focused at the "5610" mark again, look at the "5620" point at midframe, the people in the tractor trailer, the extreme sides of the shot... i used the same adapter for this pic that i used for the k28/3.5, only this m28/3.5 lens blows the other lens completely away, with the possible exception of center resolution.

https://www.dropbox.com/s/86ch2xumwhq060r/DSC01364smcm283point5f8.JPG

so... which lens would you use for landscape shots, on any camera?

[monochrome]

Your K28/3.5 needs a colimation adjustment. Either that or my M28/2 does.

This conversation is tiresome. Thankfully, it will shortly be resolved.

[stevebrot]

the things i'm talking about here will be difficult to understand for people who don't have experience with 36mp mirrorless...

The thing that is difficult to understand is the exquisite fine motor control you must have to actually nail focus with your K 28/3.5 at 100 yards. Even if the mechanical stop were beyond infinity, focus lash alone would make it extremely difficult (actual lens linear motion is on the order of microns). That is the point I have been trying to make and that is fairly evident just looking at the distance scale for the lens.



To be fair, I don't have a K 28/3.5 or M 28/3.5 and it may that both have divinely smooth and silky mechanism allowing for extremely fine control where a micrometer adjustment might normally be required. I tried backing off with my lenses, but even the slightest movement off mechanical hard stop put the plane of focus much closer than 100 yards.

That being said and totally shifting topics, I agree with monochrome that there may be something wrong with your lens. Other than the center third, the image in the K 28/3.5 version is not just soft, it is smeared.


Steve

[osv]

I tried backing off with my lenses, but even the slightest movement off mechanical hard stop put the plane of focus much closer than 100 yards.

using magnification in the lcd, does it look like the lens rotates past the focus point at 100 yards? because with cheap adapters on mirrorless, the register distance is slightly less, in order to guarantee focus ring rotation beyond what passes for infinity focus, when the lens is on a dslr... so you can smoothly approach the 100 yard mark from either direction, which minimizes the backlash effect.

with many lenses, the rotational distance to sharp focus, when you are within several feet of the target area at 100 yards, is less coming into it from the backside of the focus point... so you rotate back and forth to establish both ends of the focus range, then stop right after creeping into it on the back rotation stroke.

but that still may not be enough; modern lenses, as gofour3 alluded, have better coatings, and they can sometimes blip a very small focus peaking mark, even wide open, using a wide angle lens at a distance that's so long i can't discern maximum sharpness in the evf, even with 14.4x mag... the fa35/2 can do it in that scene, but even better, is the korean 35/1.4 lenses, here at f/2, at 300+ yards?
https://www.dropbox.com/s/0gxrx5uebxgstlk/DSC03353at2point0.JPG

when you have perfect focus like that, it's easy to see all of the problems with those junk korean lenses... fwiw, the mf functionality on that lens is very good, which addresses the point you were making.

That being said and totally shifting topics, I agree with monochrome that there may be something wrong with your lens. Other than the center third, the image in the K 28/3.5 version is not just soft, it is smeared.

on page 2 of this thread i clearly stated "i'm writing that situation off to copy variation with the k28/3.5" so we have all been in agreement there, all along.

point is, copy variation trumps everything, if we are going to talk about older and forgotten lenses being revived on the new pentax ff camera, we'd better know how to test for the problems.

[stevebrot]

when the lens is on a dslr... so you can smoothly approach the 100 yard mark from either direction, which minimizes the backlash effect.

Not with any lenses or cameras on my shelf. 100 feet maybe, but not 100 yards. With all three of my 28s 100 yards may as well be infinity. I have a friend here locally who shoots with A7RII and also has a quiver of Pentax and other glass. We are both going to be at a meetup on Sunday and I will see what he has to say.

As for sample variation...yes, indeed. This is particularly true with lenses that have been in the wild for 40+ years having been subjected to who knows what insults of abuse and bumbled service attempts during that time.

I will likely not be able to afford the new FF camera for some time, but my interest will definitely be high as people mount up the legacy film lenses. I expect there will be a few surprises similar to what I experienced with my K-3. It was a bit of a shock to have adequate performance from a few of my lenses that I expected to not be up to the challenge. I don't know why I thought that. After all, they were fine with high resolution film scanned at 4000 dpi. That is spitting distance of the K-3. The Leitz lenses from 40+ years ago perform nicely on both Leica and Sony and I would expect similar from many in the Pentax range from that same era.

BTW...I am glad you are enjoying your Sony. I took a long look at the A7 and A7R before I bought my K-3, but could not deal with the EVF...instant headache. End of discussion for me


Steve

[wombat2go]

but could not deal with the EVF...instant headache. End of discussion for me

I have the early model clip on for the Oly M4/3 now.
It does not trouble me, in fact I quite like it for still photos, but I think some would be troubled when panning.