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06-13-2010, 06:12 AM   #46
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Falconeye, that's an interesting interpretation and some well argued reasoning.

So where does APS-C fit in a Pentax line-up with a MF body and a 35mm body? Does it have a place?

06-13-2010, 06:20 AM   #47
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APS-C is the butter

QuoteOriginally posted by uccemebug Quote

So where does APS-C fit in a Pentax line-up with a MF body and a 35mm body? Does it have a place?
APS-C is the butter of the current digital offer from Pentax. Bread is dozens of small digicams. A bit of jam on top, well spread, will be a FF camera. And the drop of cream is the MF.

It's the butter that gives a delicious taste and appeal to your bread, and everything else on top of butter are good extras that makes you smile, thinking how good is to live in your house.

Last edited by Uluru; 06-13-2010 at 06:22 AM. Reason: Spelling
06-13-2010, 06:22 AM   #48
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Buy a Pentax autofocus film camera & mount 60-250 on it &

Buy a Pentax autofocus film camera & mount 60-250 on it & shoot film.

You will then see if 60-250 edge performance is worthy of full frame use.

I tried this with my old ZX-L Pentax film camera, my first Pentax camera purchase, and a Pentax Reps 16-50, 50-135 SDMs years ago.
What I saw in the viewfinder on ZX-L is not what my pictures showed me in print.
The ZX-L viewfinder is not 100% view so vignetting is not as pronounced.

If anyone here is curious about the full frame performance of any current aps-c lens then buy a camera like Pentax ZX-L and shoot some film at different apertures.

ZX-L allows one to control aperture of aps-c pentax lenses which makes it a great full frame testing camera.

Its that simple.

All your Pentax aps-c lens' EDGE PERFORMANCE on full frame platform questions will have answers




QuoteOriginally posted by falconeye Quote
George, you'll find all available info in the https://www.pentaxforums.com/forums/pentax-slr-lens-discussion/31629-da-lens-...ts-thread.html.

Until I actually did a serious measurement of this lens, I judge it based on the fact that Pentax patented the lens as a full frame lens and that me and several others cannot see any sign of vignetting when looking through a FF viewfinder (just tried again). I've seen the serious vignetting claim as well (1 Chinese post) and don't believe it. I actually watched the exit pupil getting obscured at a given angle which lies slightly outside the full frame image plane.

The DA*300 is patented as a full frame lens too but not every DA lens is. E.g., the DA 70 is patented as an APS-C lens.


Tell me what you want. But the end of APS-C lenses in 2008 (with the DA15 being the only late comer in early 2009) and the obscured release of five FF lenses over the last two years speaks for itself (*).

Rather, I believe 2008 marks the year where Pentax has changed its roadmap, defining 2011 as the year to release an FF camera and 2010 to finish their MF project. And 2009 to finish their K-7 project which must have started 2006/2007 right after release of the K10D when they still were APS-C convicted.

I don't know if Pentax would announce a 2011 camera as early as PK 2010. But they'll better do. Because Pentaxians will likely migrate in masses if they don't. It would be a shame if Pentax eventually released their FF camera with no Pentaxians left to buy it

__
(*) DA*55/200/300 released in 2008 and DFA100 being only mechanically different (released in 2010) tells us that lenses developped in 2nd half of 2008, in 2009 and in 2010 are held back (with the notable exception of the DA15 which I declare a 2008 late comer ). Held back what for? Remember the 1.4x converter disappearance already showcased during PK 2008? Realize that an 1.4x/1.5x converter will make any DA lens fit for FF? So, this is my educated guess based on pure speculation (but I am good at this...):

When FF releases, there will be 4 new lenses: DFA 28-80 standard zoom, DFA*24-70/2.8 and DFA*70-200/2.8 star zooms, and a sub-20 UWA DFA zoom or prime. One lens per year (2008/09/10/11) the FF project took them to deliver.














So, putting 2+2 together, this is MY prediction:
  • All in 2011:
  • Pentax xxx 135mm digital SLR
  • DFA lineup: 28-80, 100Macro, UWA?
  • DFA* zooms: 24-70, 70-200, 60-250 (maybe replacing the 70-200 for 2011), UWA?
  • DFA* primes: 55, 200, 300, UWA?
  • FA Limiteds: 31, 43, 77
  • DFA-DA adapter: 1.4x/1.5x converter
I am just not 100% sure that September will be the date where all this is announced yet.

UPDATE:

Actually, the decision for their FF development project back in 2008 was actually leaked by Shibata, Chi Ho! We may not have taken notice or forgot, but here it is:
Pentax SLR-rich product line general manager Ho Chi Shibata interview

The relevant sentence in a better translation (Franka T.L.):

(which in short words means: "we have decided to go FF")

So every move we have seen by the inner circle of Pentax after 2008, June 21 must be analyzed with taking their knowledge of this decision to eventually release an FF product into account.

E.g., this is what Ned Bunnell wrote back in April 2009 when discussing rumors the K-7 may be FF:

So, from what we know now, this probably exactly is what Pentax did

Last edited by Samsungian; 06-13-2010 at 06:37 AM.
06-13-2010, 07:21 AM   #49
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QuoteOriginally posted by Samsungian Quote
Buy a Pentax autofocus film camera & mount 60-250 on it & shoot film.
[...]
Its that simple.

All your Pentax aps-c lens' EDGE PERFORMANCE on full frame platform questions will have answers
This is exactly what we do in the thread I linked with first in my post. A thread you didn't obviously look into. It's the reference and you should contribute if you did test shots.

The 60-250 test is on my to-do list. But it's not that simple. To shoot test charts, scan and numerically evaluate is hard work. And to evaluate vignetting with hard gradation film is even harder work. And then to know what corner performance to expect for an official full frame lens is yet another question...

06-13-2010, 07:43 AM   #50
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QuoteOriginally posted by Samsungian Quote
Buy a Pentax autofocus film camera & mount 60-250 on it & shoot film.

You will then see if 60-250 edge performance is worthy of full frame use.

I tried this with my old ZX-L Pentax film camera, my first Pentax camera purchase, and a Pentax Reps 16-50, 50-135 SDMs years ago.
What I saw in the viewfinder on ZX-L is not what my pictures showed me in print.
The ZX-L viewfinder is not 100% view so vignetting is not as pronounced.

If anyone here is curious about the full frame performance of any current aps-c lens then buy a camera like Pentax ZX-L and shoot some film at different apertures.

ZX-L allows one to control aperture of aps-c pentax lenses which makes it a great full frame testing camera.

Its that simple.

All your Pentax aps-c lens' EDGE PERFORMANCE on full frame platform questions will have answers
The MZ-S, MZ-3 or ZX-5n would be better choices than the L.
06-13-2010, 07:54 AM   #51
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Both lenses I tried vignetted, but I did not note apertures, focal lengths

Both lenses I tried vignetted, but I did not note apertures, focal lengths.
I shot images of my car outside the camera shop.
Now I have no local Pentax Rep, & no one carries Pentax SDM locally.

Just inside the black vignetting the edge performance was fuzzy also.
Its not a crisp line with sharp detail to the circular darkened edges.

I did the test as back then the HOT Rumor was Pentax would have aps-h soon.

That aps-h was a fun rumor, some 3 years ago, yet to flesh out as fact, as usual...




QuoteOriginally posted by falconeye Quote
This is exactly what we do in the thread I linked with first in my post. A thread you didn't obviously look into. It's the reference and you should contribute if you did test shots.

The 60-250 test is on my to-do list. But it's not that simple. To shoot test charts, scan and numerically evaluate is hard work. And to evaluate vignetting with hard gradation film is even harder work. And then to know what corner performance to expect for an official full frame lens is yet another question...

Last edited by Samsungian; 06-13-2010 at 08:01 AM.
06-13-2010, 07:57 AM   #52
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Why are your listed cameras superior to ZX-L for using aps-c Pentax glass ?

Why are your listed cameras superior to Pentax ZX-L for using aps-c Pentax glass to shoot film ?

Do they note focal length and aperture on edge of negative ?

Or ?

I liked my ZX-L for my vignetting test as I owned it, bought it new, and still functions right.


QuoteOriginally posted by Blue Quote
The MZ-S, MZ-3 or ZX-5n would be better choices than the L.
06-13-2010, 08:08 AM   #53
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QuoteOriginally posted by Samsungian Quote
Why are your listed cameras superior to Pentax ZX-L for using aps-c Pentax glass to shoot film ?

Do they note focal length and aperture on edge of negative ?

Or ?

I liked my ZX-L for my vignetting test as I owned it, bought it new, and still functions right.
A little thing called exposure modes and metering modes and better viewfinders. Remember, the DA lenses don't have an aperture ring. Maybe I should ask you why you pick an inferior body.

06-13-2010, 08:13 AM   #54
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Dude, Pentax ZX-L is an autofocus camera

Dude, Pentax ZX-L is an autofocus camera.

It screw drives the autofucus lenses I tried:

16-50mm 2.8
50-135mm 2.8

No power zoom contacts though, so no SDM function.

The ZX-L allows one to change aperture on non aperture ring Pentax lenses



Great to know you think something "Pentax Japan" made is "inferior"




So how exactly does a bigger viewfinder impact film image vignetting output using aps-c pentax glass ???



QuoteOriginally posted by Blue Quote
A little thing called AF and better viewfinders. Remember, the DA lenses don't have an aperture ring. Maybe I should ask you why you pick an inferior body.

Last edited by Samsungian; 06-13-2010 at 08:25 AM.
06-13-2010, 08:24 AM   #55
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QuoteOriginally posted by Samsungian Quote
Dude, Pentax ZX-L is an autofocus camera.

It screw drives the autofucus lenses I tried:

16-50mm 2.8
50-135mm 2.8

No power zoom contacts though, so no SDM function.



Great to know you think something "Pentax Japan" made is "inferior"
Dude, the L has a .7 viewfinder. The power zoom features don't matter. No AF film camera can use SDM. You were the one to bring the terms inferior and superior into the discussion so don't try to pin that on me. What I said was they would be "better choices" in part because of better view finders.
06-13-2010, 09:02 AM   #56
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QuoteOriginally posted by falconeye Quote
This is exactly what we do in the thread I linked with first in my post. A thread you didn't obviously look into. It's the reference and you should contribute if you did test shots.

The 60-250 test is on my to-do list. But it's not that simple. To shoot test charts, scan and numerically evaluate is hard work. And to evaluate vignetting with hard gradation film is even harder work. And then to know what corner performance to expect for an official full frame lens is yet another question...
Test charts are not well suited for testing vignetting, as the vignetting changes with focus distance at least on lenses without IF. At farther distances, the vignetting gets more visible.

An easy option, which I often applied in the past, when testing lens hoods for vignetting is to place a peice of tracing paper on the film rails, leave the back open, open the shutter in B (with remote release and then you see vignetting easily and can go through the focus etc. Best suited for this apporach are probably old mechanical cameras. With the help of a loupe it is even possible to look for more pronounced loss of IQ near the corners.

This purely visual approach is fast and rules out all the film-related problems, though is more qualitative, then quantitative.

Ben
06-13-2010, 12:11 PM   #57
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QuoteOriginally posted by Ben_Edict Quote
Test charts are not well suited for testing vignetting, as the vignetting changes with focus distance

to place a peice of tracing paper on the film rails
Ben,

thanks for the suggestion.

I actually already tried the laterna magica method which has the advantage to deliver image circles in excess of 43mm.

For the 60-250, I however failed to take an exact measurement because I didn't construct a black box. It was around 40mm. Without a black box, the projected image at f/4 isn't that brighter than ambient light

I tried the tracing paper method but my camera either refused to trigger with an open door or didn't go to bulb with aperture in "A". So, I saw the image for a fraction of a second only. No vignetting at 60mm, a bit less sure at 135 and 250mm though.


You're correct with the focus distance dependency. At 250mm and 5m distance, the effect should be 250mm/5000mm = 5% or smaller though. Which is 1mm in the extreme corners.

I'll think about it again when I have scanned test shots
06-13-2010, 12:24 PM   #58
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QuoteOriginally posted by Groundloop Quote
Don't (some? all?) other brands FF bodies detect when an APS-C lens is mounted and default to "crop mode"? I can't see why Pentax wouldn't implement a similar scheme. Or did I imagine reading that?

Somewhere.
Nikon has that feature.

Canon crop lenses (EFS) cannot be mounted on FF bodies because the back of the lens will hit the mirror.
06-13-2010, 01:08 PM   #59
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The latter two don't allow manually setting the aperture. If you use a DA lens on them, you lose M and Av mode.



QuoteOriginally posted by Blue Quote
The MZ-S, MZ-3 or ZX-5n would be better choices than the L.
06-13-2010, 01:53 PM   #60
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QuoteOriginally posted by cousinsane Quote
The latter two don't allow manually setting the aperture. If you use a DA lens on them, you lose M and Av mode.
The L doesn't either and with the S you give up some of the pentaprism. Furthermore, the L has a pentamirror. So what is your point? That's why for AF film, the aperture rings are important. The point of this is to test for cropping in the viewfinder and on the film.
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