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02-24-2015, 11:39 AM   #1
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Da 300 on FF

Hi
Can anyone please advise whether I will be able to use my DA300 on the new FF camera without any cropping or reduced pixels etc
Thank you

02-24-2015, 12:18 PM   #2
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QuoteOriginally posted by West of the tamar Quote
Hi
Can anyone please advise whether I will be able to use my DA300 on the new FF camera without any cropping or reduced pixels etc
Thank you
The way the cropping will work is yet to be decided. However, based on user reports, the lens does cover the FF image circle.

Adam
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02-24-2015, 12:22 PM   #3
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QuoteOriginally posted by Adam Quote
The way the cropping will work is yet to be decided. However, based on user reports, the lens does cover the FF image circle.
But possibly not with Shake Reduction turned on, that's yet to be determined.
02-24-2015, 12:46 PM   #4
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The DA 300mm has an image circle big enough for FF. It works on film. The question is just whether a FF sensor will still have enough extra room for SR.
Anyway, see this thread for a quick reference:
https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/31629-da-le...ts-thread.html

02-24-2015, 01:16 PM   #5
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QuoteOriginally posted by normhead Quote
But possibly not with Shake Reduction turned on, that's yet to be determined.
Unless pentax intentionally disable SR for those lenses, I do not think a reason why SR will not work. A general advantage for in body SR is that it can apply to all the lenses...
02-24-2015, 01:24 PM   #6
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QuoteOriginally posted by starjedi Quote
Unless pentax intentionally disable SR for those lenses, I do not think a reason why SR will not work. A general advantage for in body SR is that it can apply to all the lenses...
The SR needs the projected image circle to be big enough, or it will "shift" out of it. But there is some debate over how much bigger the image circle actually has to be, how much space SR needs. Some say it is very little space, others say it is many mm
02-24-2015, 01:41 PM - 1 Like   #7
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QuoteOriginally posted by normhead Quote
But possibly not with Shake Reduction turned on, that's yet to be determined.
Possibly, but that theory is exaggerated IMO.

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02-24-2015, 02:42 PM   #8
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QuoteOriginally posted by Na Horuk Quote
The SR needs the projected image circle to be big enough, or it will "shift" out of it. But there is some debate over how much bigger the image circle actually has to be, how much space SR needs. Some say it is very little space, others say it is many mm
Maybe that instead of correcting 4 F-stops they only correct 2 F-stops.

02-24-2015, 02:45 PM   #9
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QuoteOriginally posted by Adam Quote
Possibly, but that theory is exaggerated IMO.
Agreed - Pentax is pretty much committed to releasing FF cameras with in-body SR now, since the new D FA 70-200 and 150-450 don't have SR in the lens. They can't sell a 70-200/2.8 for the exact same price as Canon and Nikon without SR capability.

SR will have to use the full image circle to compete.
02-24-2015, 03:20 PM   #10
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QuoteOriginally posted by DSims Quote
Agreed - Pentax is pretty much committed to releasing FF cameras with in-body SR now, since the new D FA 70-200 and 150-450 don't have SR in the lens. They can't sell a 70-200/2.8 for the exact same price as Canon and Nikon without SR capability.

SR will have to use the full image circle to compete.
I think the suggestion is the DA 300mm can "just" fill a full frame where a full frame lens + SR support needs to have a bigger image circle (so when SR shifts the sensor around, it doesn't vignette to all heck).
02-24-2015, 04:57 PM   #11
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QuoteOriginally posted by Adam Quote
Possibly, but that theory is exaggerated IMO.
It all comes from an interview that John Carlson did with IR back in 2012. Q&A with Pentax’s John Carlson and Genichiro Takaoka: Is full-frame coming, and what’s next for medium format?

DE: "Speaking of the lenses, this was another reader question: There are rumors that many of your APS-C lenses might actually have full frame circles but they’re not advertised as such. Can you shed some light on that?"

John Carlson: "All the tests I’ve seen, if you put those lenses on a film body, you get vignetting. So they’re bigger than if it were just an APS-C without shake reduction, but that added image circle is just to accommodate the shake reduction, it doesn't accommodate full-frame."

Of course John works in the marketing dept. so there is a very good chance he doesn't even know what shake reduction it.
02-24-2015, 07:17 PM   #12
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QuoteOriginally posted by phoned Quote
I think the suggestion is the DA 300mm can "just" fill a full frame where a full frame lens + SR support needs to have a bigger image circle (so when SR shifts the sensor around, it doesn't vignette to all heck).
This is possible - to directly answer the OP's question, legacy glass like the DA*300 could possibly have some crop with SR. But new glass will have to cover FF with SR on.

Also keep in mind that many digital ILC manufacturers are now compensating for vignetting in-camera, so it's possible this will be handled by processing without actually cropping the image.
02-24-2015, 07:41 PM   #13
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QuoteOriginally posted by DSims Quote
This is possible - to directly answer the OP's question, legacy glass like the DA*300 could possibly have some crop with SR. But new glass will have to cover FF with SR on.

Also keep in mind that many digital ILC manufacturers are now compensating for vignetting in-camera, so it's possible this will be handled by processing without actually cropping the image.
Another interesting possibility.... that being said, someone found the patent for the new 70-200 on the web, it was a 2012 patent, and the image circle was more than 4mm bigger than it needed to be to cover a 35x 24 sensor. At the time most of us thought "ah ha, shake reduction."

The other thing of relevance is I don't know how big the image circle from the DA*300 is. For all I know it's as big as the image circle for the 70-200 ƒ2.8.

I would be a lot less confident about this, if shake reduction didn't constantly cause vignetting on my 18-135, it's lens designed for APS-c and they didn't make it big enough to work correctly with SR. Now your telling me that lenses signed for APS-c are big enough to work flawlessly with FF SR. I'm dubious.
02-24-2015, 08:41 PM   #14
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This should be testable before the real camera comes out.
Going by the claim I read that the K-3 sensor moves +-1.5mm, we need to see the image circle over at least 27x39mm (47.4mm diagonal).
I tried using a ground glass screen at the back of my old film camera to test this but I saw that the test wouldn't work because the focal plane gets masked to 24x36mm. Since I don't feel like wrecking my old camera just yet, I found a cheap extension tube to mount lenses on and could get close (45.6mm) to the Pentax 45.46mm flange to focal plane distance.
I compared the image circle of a 100mm DFA Macro (about 50mm or so, vignetting made measuring hard) to the 300mm DA* (about 48mm).
There didn't seem much vignetting within that 48mm on the 300mm and that should be enough to cover that 47.4mm diagonal we need (assuming the full frame sensor doesn't have much more movement than +-1.5mm).
It was all done hand held though, so I should mount the lens on a tripod, measure more accurately and take some photos of the glass screen to post.

John.
02-28-2015, 06:39 AM   #15
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Does it mean anything for this discussion of what the da*300 will be like on the Pentax
FF that it performs beautifully on the Sony A7II with shake reduction enabled?
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