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08-25-2010, 06:49 PM   #16
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QuoteOriginally posted by clark Quote
maybe a stupid question, but I guess you can't put pentax 35mm lenses on the 645? Would be very tempted if you could use pentax m glass on it
but I doubt you can
no, it isn't possible. the focus flange on the 645D ( the distance from the mount to the camera sensor) is significantly longer than that of Pentax K mount camera bodies.

08-25-2010, 06:53 PM   #17
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QuoteOriginally posted by clark Quote
maybe a stupid question, but I guess you can't put pentax 35mm lenses on the 645? Would be very tempted if you could use pentax m glass on it but I doubt you can
Different mount. The 645 lenses must cover a larger image circle. You can however go the other way and get an adapter for 645 lenses on K-mount (35mm and and APS-C). Or even 6x7 lenses on k-mount.
08-26-2010, 03:23 AM   #18
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QuoteOriginally posted by Digitalis Quote
no, it isn't possible. the focus flange on the 645D ( the distance from the mount to the camera sensor) is significantly longer than that of Pentax K mount camera bodies.
Well, that's correct but it's not the complete truth. Obviously using K lenses at infinity is not possible, but using them as macro lenses on the 645 (even the film ones) is doable. A wildlife photographer here in Italy some years ago was using K-A*200/4 macro e K-F*300/4,5 for flowers close up on a Mamiya 645, mounting them wiha self made adapter using a body-cap for the camera.
08-26-2010, 05:31 AM   #19
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QuoteOriginally posted by eurostar Quote
Well, that's correct but it's not the complete truth. Obviously using K lenses at infinity is not possible, but using them as macro lenses on the 645 (even the film ones) is doable. A wildlife photographer here in Italy some years ago was using K-A*200/4 macro e K-F*300/4,5 for flowers close up on a Mamiya 645, mounting them wiha self made adapter using a body-cap for the camera.

That's all fair and good, but using a 35mm lens even on reduced frame 645 is a bit daft IMO. That is what extension tubes are for, Pentax 645 FA*300mm f/4 ED IF is superb for such things. Mamiya doesn't make many telephoto lenses for their 645 range of cameras,Last I heard they are discontinuing their 500mm f/8 mirror lens. Carl Zeiss doesn't make many either, And that has always been a strength of the Pentax medium format system, the fast telephoto lenses.


Last edited by Digitalis; 08-26-2010 at 05:44 AM.
08-26-2010, 06:41 AM   #20
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Wow...any processing done on that TIFF conversion at all?
If that was ISO1600, that's pretty impressive...I don't see much noise in the crop at all :-O
08-26-2010, 07:41 AM   #21
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QuoteOriginally posted by rparmar Quote
Different mount. The 645 lenses must cover a larger image circle. You can however go the other way and get an adapter for 645 lenses on K-mount (35mm and and APS-C). Or even 6x7 lenses on k-mount.
thanks

maybe i don't understand medium format, but surely with a 50mm 2.8 as the standard lens compared to a 50mm 1.4 on 35mm- you lose 2 stops of light, so the iso has to be increases by 2 stops to compensate

or is the medium format sensor inheritantly more 'sensitive' at the same ISO?
08-26-2010, 07:54 AM   #22
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"maybe i don't understand medium format, but surely with a 50mm 2.8 as the standard lens compared to a 50mm 1.4 on 35mm- you lose 2 stops of light, so the iso has to be increases by 2 stops to compensate

or is the medium format sensor inheritantly more 'sensitive' at the same ISO?"

no, the sensor on the 645D is 44X33mm in comparison full frame 24X36mm. With the 645D the bigger the format the shallower DOF will be. So technically a 55mm f/2.8 on the 645D is the 35mm equivalent FOV of a 43mm lens, and the equivalent depth of field of a f/1.1 lens.

ISO sensitivity on the 645D is the same as all other digital SLR cameras, the sensor isn't any more sensitive than any other, it's just bigger.
08-26-2010, 09:23 AM   #23
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QuoteOriginally posted by Digitalis Quote
"maybe i don't understand medium format, but surely with a 50mm 2.8 as the standard lens compared to a 50mm 1.4 on 35mm- you lose 2 stops of light, so the iso has to be increases by 2 stops to compensate

or is the medium format sensor inheritantly more 'sensitive' at the same ISO?"

no, the sensor on the 645D is 44X33mm in comparison full frame 24X36mm. With the 645D the bigger the format the shallower DOF will be. So technically a 55mm f/2.8 on the 645D is the 35mm equivalent FOV of a 43mm lens, and the equivalent depth of field of a f/1.1 lens.

ISO sensitivity on the 645D is the same as all other digital SLR cameras, the sensor isn't any more sensitive than any other, it's just bigger.
you're probably facepalming right now but...

i get the 'crop' factor thing, I understand that a 55mm will be 0.8x the 35mm equivalent, so will give the FOV of a 43mm as you say, but in terms of 'light gathering ability' it's still an f2.8 lens, so surely only lets in f2.8 worth of light, so compared to an f1.4 lens surely this would be worse for low light shooting- or is the physical size of the aperture on 645 lenses larger, i.e. is an 645 f2.8 going to have a 'bigger hole' and transmit more/less/the same amount of light to the 645 sensor as an f1.4 transmits to a 35mm frame of film

i'm sorry i've never shot MF before and until now i've never really been interested in the format, I know these are largely banal questions but i'm just trying to figure out the low light capability of medium format vs 35mm, not that i'm ever likely to own MF and not that it even matters, i'm just curious


Last edited by clark; 08-26-2010 at 09:32 AM.
08-26-2010, 11:54 AM - 1 Like   #24
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QuoteOriginally posted by clark Quote
you're probably facepalming right now but...

i get the 'crop' factor thing, I understand that a 55mm will be 0.8x the 35mm equivalent, so will give the FOV of a 43mm as you say, but in terms of 'light gathering ability' it's still an f2.8 lens, so surely only lets in f2.8 worth of light, so compared to an f1.4 lens surely this would be worse for low light shooting- or is the physical size of the aperture on 645 lenses larger, i.e. is an 645 f2.8 going to have a 'bigger hole' and transmit more/less/the same amount of light to the 645 sensor as an f1.4 transmits to a 35mm frame of film

i'm sorry i've never shot MF before and until now i've never really been interested in the format, I know these are largely banal questions but i'm just trying to figure out the low light capability of medium format vs 35mm, not that i'm ever likely to own MF and not that it even matters, i'm just curious
Lets say that someone built a f1.4 lens for a MF...that would be some beast...the thing is that it would correspond in terms of depth of focus to something well below f1. If you use it for low light conditions and shoot wide open, your DOF will be sooooo thin that you would have a great problem finding anything sharp anywhere in any picture. Not much use of the speed then. That, and the astronomical cost of such a lens, is why a MF lens is considered fast at f2.8. If you want to isolate the subject against a smooth OOF field, f2.8 does it as well as a f1.4 does on 35mm film. If f2.8 doesn't let in enough light for you, you have to increase the shutter speed, even if it may require a tripod.

Nice review btw.
08-26-2010, 11:56 AM   #25
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Nice detail in the picture. That is one great camera to use. Yes of course some things could improve, but hey it's a first for Pentax and they made it real cheap so some compromise is okay. The compromise is not image-wise and that is the main thing to me.

One correction: your cards probably write at a speed of 15 Mb/s so that wil take an extra second. Did you make sure to not activate lenscorrections wich slows it down, and also not activating the view of the picture makes it faster to use again. So some speed is there to win.
08-26-2010, 12:02 PM   #26
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QuoteOriginally posted by Douglas_of_Sweden Quote
Lets say that someone built a f1.4 lens for a MF...that would be some beast...the thing is that it would correspond in terms of depth of focus to something well below f1. If you use it for low light conditions and shoot wide open, your DOF will be sooooo thin that you would have a great problem finding anything sharp anywhere in any picture. Not much use of the speed then. That, and the astronomical cost of such a lens, is why a MF lens is considered fast at f2.8. If you want to isolate the subject against a smooth OOF field, f2.8 does it as well as a f1.4 does on 35mm film. If f2.8 doesn't let in enough light for you, you have to increase the shutter speed, even if it may require a tripod.

Nice review btw.
thank you, that clears everything up
08-26-2010, 03:02 PM   #27
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QuoteOriginally posted by Warped Quote
No worries at all Adam.

Should this post be moved to the 645D review page or copied there?

A wide angle lens is top of my wish list for the first thing to buy once the 645D is in my hands - after that, a 120mm Macro is next and I think I'll be pretty happy with those 2 lenses and the 2.8 55mm.
An Ultrawide and something like a 24mm or wider would be awesome .... I'd definitely grab one.

As for the dough - this camera will end up costing me well over $20K ..... the refinancing to afford the 645D also meant some extra cash for home renovations. a new pc and a few other bits and pieces ....... but when we refinanced our home loan it ended up costing me an extra $30 a fortnight so not to bad
(just got to silence the little voice in my head it's $30 a fortnight for the next 10 to 15 years!!!).
If you'd like, you're welcome to post a review there as well.

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08-26-2010, 04:52 PM   #28
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QuoteOriginally posted by RonHendriks1966 Quote
Nice detail in the picture. That is one great camera to use. Yes of course some things could improve, but hey it's a first for Pentax and they made it real cheap so some compromise is okay. The compromise is not image-wise and that is the main thing to me.

One correction: your cards probably write at a speed of 15 Mb/s so that wil take an extra second. Did you make sure to not activate lenscorrections wich slows it down, and also not activating the view of the picture makes it faster to use again. So some speed is there to win.
Yes I had the image preview turned on as I did want to check my shots as I wasn't all that used to the 645D, but did not have lens corrections activated.

QuoteOriginally posted by kenyee Quote
Wow...any processing done on that TIFF conversion at all?
If that was ISO1600, that's pretty impressive...I don't see much noise in the crop at all :-O
That shot and crop is from an ISO200 image. The ISO1600 images I shot on the night are yet to posted up anywhere but will get around to that shortly.
08-27-2010, 02:28 AM   #29
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QuoteOriginally posted by Warped Quote
A wide angle lens is top of my wish list for the first thing to buy once the 645D is in my hands - after that, a 120mm Macro is next and I think I'll be pretty happy with those 2 lenses and the 2.8 55mm.
An Ultrawide and something like a 24mm or wider would be awesome .... I'd definitely grab one.

Pentax presented a mockup of a 28mm f/4 lens with drop in filters - not sure when it will be announced (probably soonish) looks like Pentax's answer to the Mamiya/Phase one 28mm f/4.5 ASPH - the lens will most likely feature ED and (hopefully some Aspherical elements too) SDM WR and enhanced optical coatings.
08-27-2010, 03:34 AM   #30
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QuoteOriginally posted by Digitalis Quote
Pentax presented a mockup of a 28mm f/4 lens with drop in filters - not sure when it will be announced (probably soonish) looks like Pentax's answer to the Mamiya/Phase one 28mm f/4.5 ASPH - the lens will most likely feature ED and (hopefully some Aspherical elements too) SDM WR and enhanced optical coatings.
Hopefully my bank account will have recovered from the 645D and the 2.8 55mm by then!
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