Hi everybody,

I would like to open up a thread dedicated to one topic:

DA lens on Full Frame: a sticky test shots thread.

This thread shall be dedicated to test shots of a DA lens mounted to a full frame body (e.g., a film camera body). By test shot, I mean shots dedicated to evaluate the performance. Shots of ordinary subjects aren't suitable to this task, normally, and should not be posted. So, these are the rules:

• K mount lens dedicated to the APS-C form factor is used.
• Image is taken full frame 36mm x 24mm.
• Lens hood was removed.
• And ideally, no filter is mounted.
• The aperture used is specified (note that film cameras don't record EXIF...).
• Sample image shows the entire field of view.
• Sample image(s) show(s) corner, border and center performance at 10MP-100% (multiple crops, or single not-resized image).
• The subject is such that resolution and vignetting at the borders can be compared to the center.

The idea behind this thread is obvious: To compile enough data to assess the spectrum of available lenses for a forthcoming full frame DSLR in K mount.

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Table of results as obtained in this thread (updated regularly):

SMC Pentax-DA primes...

• DA 14mm F2.8: - (clawhammer)
• DA 15mm F4.0: - (Zav)
• DA 21mm F3.2 Limited: - (Boris Liberman)
• DA 35mm F2.4 AL: +++ (aurele ;like FA35/2.0 and no vignetting) (frank)
• DA 35mm F2.8 Limited Macro: 0 (ryno), + (@ 1.15 crop)
• DA 40mm F2.8 Limited: +
• DA* 55mm F1.4 SDM: +++ (aurele)
• DA 70mm F2.4 Limited: +
• D FA Macro 100mm F2.8 WR: +++ (officially specified FF by Pentax)
• DA* 200mm F2.8 ED [IF] SDM: +++? (common belief, but is it true?)
• DA* 300mm F4 ED [IF] SDM: ++ (officially rated "designed for FF" by Pentax patent US7715116)

SMC Pentax-DA zooms...

• DA 10-17mm F3.5-4.5 Fish-Eye ED [IF]: FE, see #59, #61, #94. 10mm: heavy vignette / 14mm: almost no vignette / 17mm ++ (Reps, froeschle, Gooshin)
• DA 12-24mm F4 ED AL [IF]: - (below 16mm, xitek.com), o (at 18mm, architorture), + (at 20mm, architorture), ++ (at 24mm, architorture)
• DA 16-45mm F4: - (below 21mm, Nesster)
• DA* 16-50mm F2.8 ED AL [IF] SDM: - (xitek.com)
• DA 17-70mm F4 AL [IF] SDM: - (KjetilH)
• DA 18-55mm F3.5-5.6 AL: - (at 18mm, Spongefingers; below 23mm, xitek.com)
• DA 18-55mm F3.5-5.6 AL II: missing
• DA 18-250mm F3.5-6.3 ED AL [IF]: - (xitek.com)
• DA 50-200mm ED: -
• DA* 50-135mm F2.8 ED [IF] SDM: - (elho_cid)
• DA* 60-250mm F4 ED [IF] SDM: ++ (officially rated "designed for FF" by Pentax patent US7489452) probably good on full frame but evaluation still missing; the rating is +++ with a baffle modification, + without)
• DA 55-300mm F4-5.8 ED: 0 (+, ++ at tele end, viking79)

Sigma K mount DC...

• Sigma 18-200mm f/3.5-6.3 DC: -
• Sigma 10-20mm f/4-5.6 DC: - (below 14mm, Gooshin)
• ...

Tamron K mount Di-II...

• ...

Overall rating scale:
+++: no significant difference between APS-C and FF corners
++: difference but usable at full aperture with a small loss in corner IQ only
+: usable staring at f/4~f/5.6, with no or a small loss in corner IQ only
o: usable at f/11 or with big loss in corner IQ only
-: not usable

[aurele]

For kicks, I mounted the new 18-50 collapsing kit lens that comes with the K-S2 on my MG. Obviously, the lens can't be focused without ca camera power source. Nor can it be stopped down. So it's useless except at infinity and wide open with most Pentax bodies. That said, on FF, it vignettes with a clear image circles and corner cut-off in the viewfinder from 18mm to 24mm on the MG. Given that the MG has a smaller viewfinder, it could be assumed that it would vignette up to 28mm. One interesting thing is that the entire image is sharp. I had a vertical slat fence on the side of the viewfinder and there was significantly less distortion at 18mm in the out-of-APS-C-image-circle area than expected. In fact, the out-of-circle area was nearly as sharp as the in-circle area.

The 18-50 use the same formula as the DA 18-55, so it should produce the same results : vigneting from 18 to 24, stopping down possible with "A" contact bodies, quite sharp from 24 to 50 wide open.

[K David]

stopping down possible with "A" contact bodies, quite sharp from 24 to 50 wide open.

Will the A bodies support he manual focus fly by wire that the new lens has?

[stevebrot]

Will the A bodies support he manual focus fly by wire that the new lens has?

I think not. The A-series bodies have no way to power the lens.


Steve

[UncleVanya]

I'm guessing any power zoom capable body (or SDM) will work for the powered focus by wire option.

[aurele]

Will the A bodies support he manual focus fly by wire that the new lens has?

No, of course not, but it will handle the aperture without having an aperture ring. Having the possibility to change aperture is the minimum to use a lens.
K body will always stop the lens down to f22-32.

---------- Post added 1st Apr 2015 at 05:22 PM ----------

I'm guessing any power zoom capable body (or SDM) will work for the powered focus by wire option.

No, only bodies that handle the SDM can focus using the contact.
So : no film body can AF with SDM lenses.

The fact that a body can handle powerzoom bas nothing to do with SDM focusinc capability.

[UncleVanya]

No, only bodies that handle the SDM can focus using the contact.
So : no film body can AF with SDM lenses.

The fact that a body can handle powerzoom bas nothing to do with SDM focusinc capability.

I never said it could do SDM. I said the lens can possibly work in Manual Focus because it gets the power to do the POWERED manual focus by wire from the SDM/Power Zoom contacts. Obviously the SDM focusing itself won't work anymore than it works on a K100D.

Do you know for a fact that the lens fails to focus manually on a film camera with power zoom?

[aurele]

I never said it could do SDM. I said the lens can possibly work in Manual Focus because it gets the power to do the POWERED manual focus by wire from the SDM/Power Zoom contacts. Obviously the SDM focusing itself won't work anymore than it works on a K100D.

Do you know for a fact that the lens fails to focus manually on a film camera with power zoom?

i don't know for a fact that it can't.
But considering the way the lens communicate with the body : the body ask if the lens is powerzoom. SDM answer is no, so the contact aren't powered (tested on my 3 film bodies). At least on the MZ series.

We can wait further test, but i don't have a lot of hope.

Are you sure it's focusing by wire ?

[UncleVanya]

i don't know for a fact that it can't.
But considering the way the lens communicate with the body : the body ask if the lens is powerzoom. SDM answer is no, so the contact aren't powered (tested on my 3 film bodies). At least on the MZ series.

We can wait further test, but i don't have a lot of hope.

Are you sure it's focusing by wire ?

Yes. The first impressions review listed here: Pentax 18-50mm F4-5.6 First Impressions Review - Hands-on Reviews | PentaxForums.com

One interesting side-effect of the 18-50mm's compact design is a motor-actuated manual focusing system. Rather than being mechanically linked to the lens, the focusing ring sends digital signals to the DC motor, which in turn adjusts the focus. As a result, the new 18-50mm supports "quick-shift" manual focus overriding, unlike any other DA L lens. There is unfortunately a little bit of latency when focusing, and it is not as easy to make precise adjustments, so we would have preferred the traditional mechanical implementation.
This type of manual focusing system is a first for Pentax K-mount lenses. It also means that the earliest Pentax DSLRs (*ist D, K100D) cannot be used with this lens, since there would be no power for the DC motor and you won't be able to focus (even manually). Likewise, manual focusing will be unavailable when your camera is turned off.

This seems to indicate that K100D can't do this but I don't think it was tested.

[Caat]

I am guessing that Pentax could profile lenses like the DA* 60-250mm specifically for the new FF camera - i.e. the vignetting correction and distortion correction could be tailored for it. Which might help a bit if you don't want to go to the PP effort yourself. I am hoping that Pentax has various auto-cropping options with some way of indicating this in the viewfinder. Would be interesting if they could have a variable auto-crop mode that gave you the widest possible high-quality view and whatever focal length you were at. But that would be a lot of work to programme for a minor convenience gain for some people in some instances.

[falconeye]

I am guessing that Pentax could profile lenses like the DA* 60-250mm specifically for the new FF camera - i.e. the vignetting correction and distortion correction could be tailored for it. Which might help a bit if you don't want to go to the PP effort yourself. I am hoping that Pentax has various auto-cropping options with some way of indicating this in the viewfinder. Would be interesting if they could have a variable auto-crop mode that gave you the widest possible high-quality view and whatever focal length you were at. But that would be a lot of work to programme for a minor convenience gain for some people in some instances.

IIRC, the 60-250 vignettes slightly at the long end. However, that's no problem as it doesn't at the wide end and it is easy to crop into longer FL to avoid it. So, one wouldn't want the Pentax FF to autocrop the 60-250. But Pentax probably will think differently as they may think to assert operation at all FL.

Just another case where the world isn't black or white.

[Na Horuk]

The best solution would be if the Pentax FF had four options:
a) No crop. Photos taken at FF, even if lens' image circle is too small. Basically like shooting film.
b) Always crop. Photos cropped to APSC regardless of image circle. This would allow for smaller file size, maybe even faster burst mode and extra "sensor shift".
c) Auto-crop to APSC. For FF Pentax lenses and manual lenses, the camera would use FF area. For certain Pentax lenses, camera would crop to APSC
d) Auto-crop to fit. If lens is okay at 60mm, no crop. If the same lens is not okay at 250mm, then crop it to whatever dimensions it requires at that focal length (not necessarily APSC crop, might be 1.2x or whatever Pentax engineers determined would make sense.).

c and d would probably only work for Pentax lenses. Third parties would just be assumed to be FF.
Focus also affects the size of image circle. I don't think the camera can know where exactly the focus is set, so it would just assume worst case scenario for that part of the image circle equation

[UncleVanya]

It might also be possible to have a variable crop ratio and set the crop per lens like you set AF adjustments today. This would only work on modern lenses with communication with the body.

EDIT: To be clear Variable in this case was not meant to be a continuously variable ratio that scales as the lens zooms etc. What I was talking about was the ability to set a specific crop value out of a set of preset ratio choices to be associated/default with the use of a particular (modern) lens based on a user selection.

I realize this might have been mistaken for something more like the continuous zoom crop that was previously mentioned and wanted to clarify what I meant.

[falconeye]

d) Auto-crop to fit.

Yeah, I'll wait for the following to happen: You zoom the lens out and the LV image zooms in. Because this is what can happen if you make the crop depend on focal length. Pentax will never do that, for a reason.

This is why there will probably only be 1 or 2 crop factors (1.5x, 1.3x) to be used for all lenses. Esp. as you need a marker in the VF. Nikon has a few discrete crop factors too.

[Class A]

... even as the OP, I cannot modify my OP anymore

If you contact Adam with a PM, he should be able to grant you indefinite access to your first post.

[falconeye]

If you contact Adam with a PM, he should be able to grant you indefinite access to your first post.

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/31629-da-le...ml#post2371431