[RiceHigh]

Is derived to be 44 x 33mm by me, see my calculations based on existing officially disclosed information so far:-

RiceHigh's Pentax Blog: Sensor Size of the 645D (and More Technical Talks on DSLR Form Factors)

Happy reading!

[kenyee]

Pentax isn't the only MF digital system to crop. AFAIK, the only non-cropped MF digital system is the $40-50K PhaseOne back.
Hassies, Leica, Mamiyas all crop from 1.1 to 1.3...
I put up a table of all the competitors in one of the pentaxforums threads in case you're curious.

I tried to post this to your blog, but it apparently hates Firefox and doesn't work with it :-P

[RiceHigh]

Pentax isn't the only MF digital system to crop. AFAIK, the only non-cropped MF digital system is the $40-50K PhaseOne back.
Hassies, Leica, Mamiyas all crop from 1.1 to 1.3...
I put up a table of all the competitors in one of the pentaxforums threads in case you're curious.

I tried to post this to your blog, but it apparently hates Firefox and doesn't work with it :-P

My Blog is FireFox optimised. Just in case if you've failed to post, I guess its a Google problem.

[Sean Nelson]

Is derived to be 44 x 33mm by me, see my calculations based on existing officially disclosed information so far:

You've made a fundamental error by assuming that the 75mm lens is normal for a 60 x 45mm "sensor" (ie, film). In fact, the negative size of a film 645 camera is not 60 x 45mm, but rather 56mm x 41.5mm (see: Pentax 645NII Specifications).

...and speculating on the sensor size based on the focal length of a released lens is dubious at best, IMHO. You'll probably get an answer in the right ballpark, but there's certainly no basis to assert that it will be 44 x 33 instead of the more "standard" 48 x 36mm or even something else.

[RiceHigh]

You've made a fundamental error by assuming that the 75mm lens is normal for a 60 x 45mm "sensor" (ie, film). In fact, the negative size of a film 645 camera is not 60 x 45mm, but rather 56mm x 41.5mm (see: Pentax 645NII Specifications).

Then, it has the 120 film cropped, which I have been unaware of.

Anyway, the cropped factor is only 1.076, not a big amount though.

...and speculating on the sensor size based on the focal length of a released lens is dubious at best, IMHO.

That's why I said "based on the officially disclosed information so far".

You'll probably get an answer in the right ballpark, but there's certainly no basis to assert that it will be 44 x 33 instead of the more "standard" 48 x 36mm or even something else.

If it is really still 48 x 36, then this 55mm "standard" lens maybe a bit too wide, i.e., it is of 39mm equivalent of 135 systems for the Angle of View.

[Sean Nelson]

Then, it has the 120 film cropped, which I have been unaware of.

No camera that takes 120 film actually has a negative that is 60mm across the width of the film. All cameras have to allow a margin for the pre-exposed frame markers and numbers, not to mention the fact that the film gate HAS to be narrower than the film in order to keep it held flat. So it's not really correct to call it "cropped". This Wikepedia article lists the nominal sizes of various 120 film formats.

Anyway, the cropped factor is only 1.076, not a big amount though.

It's in the same order of difference as your resulting sensor size is from the "standard" 48 x 36 size - so it's pretty significant in terms of the results you're suggesting.

If it is really still 48 x 36, then this 55mm "standard" lens maybe a bit too wide, i.e., it is of 39mm equivalent of 135 systems for the Angle of View.

A "standard" lens is a pretty loose thing to begin with. The only vaguely agreed-upon criterion is a lens that has a focal length equivalent to the diagonal of the imaging area. That suggests a field of view equivalent to a 43mm lens on a 35mm film camera. 39mm is closer to that (percentage-wise) than the 50mm lens provided as standard with most 35mm cameras.

The vagueness in the provision of "standard" lenses for cameras is why I think trying to derive the sensor size by looking at the focal length of this new lens is basically a useless exercise.

[Haakan]

Originally posted by RiceHigh
Then, it has the 120 film cropped, which I have been unaware of.

I thought that the actual image size format of about 56x42mm was the standard for 645 cameras, just as 6x6 is about 56x56mm

Photoethnography.com - Classic Cameras

Best regards,
Haakan

[lol101]

Then, it has the 120 film cropped, which I have been unaware of.

Yes, 6x6 is actually 56mmx56mm, allowing for some space around the pictures.

[RiceHigh]

I thought that the actual image size format of about 56x42mm was the standard for 645 cameras, just as 6x6 is about 56x56mm

Photoethnography.com - Classic Cameras

Best regards,
Haakan

Oh, I see. No MF camera uses the whole frame?

[pingflood]

Oh, I see. No MF camera uses the whole frame?

Pretty much all of them use 56mm of the width (and that is the "frame"), though the film (including the frame numbers etc) is 60-61mm wide. No 35mm cameras use "the whole frame" either if you think about it.

(edit: sorry to disappoint you in that Pentax didn't produce an inferior MF film camera by cropping -- bet that'd make for some good material)

[jeffkrol]

Kodak Image Sensor Solutions - Full Frame CCD
http://www.kodak.com/global/plugins/acrobat/en/business/ISS/datasheet/fullfr...00LongSpec.pdf
If 31MP then it's probably this sensor.. Why Kodak? US to yen discount....
46.05 X 35....

[RiceHigh]

Pretty much all of them use 56mm of the width (and that is the "frame"), though the film (including the frame numbers etc) is 60-61mm wide. No 35mm cameras use "the whole frame" either if you think about it.

(edit: sorry to disappoint you in that Pentax didn't produce an inferior MF film camera by cropping -- bet that'd make for some good material)

In fact, we can forget well about the actual sensor size, the ratio of the two standard lenses, i.e. 75mm/55mm tells well about the crop factor, which is 1.36X.

[Sean Nelson]

In fact, we can forget well about the actual sensor size, the ratio of the two standard lenses, i.e. 75mm/55mm tells well about the crop factor, which is 1.36X.

Only if the two lenses have the same field of view (the 75mm on film vs. the 55mm on the 645D).

[Venturi]

In fact, we can forget well about the actual sensor size, the ratio of the two standard lenses, i.e. 75mm/55mm tells well about the crop factor, which is 1.36X.

Only if the two lenses have the same field of view (the 75mm on film vs. the 55mm on the 645D).

The 55mm lens being touted as what would ship with the 645D at this point really doesn't tell us squat about the sensor.

But for grins:
75mm on a 645/N/Nii yields an AOV of 50deg and a FOV of 9.33ft (7.47x5.6ft) from 10ft.
In order to make a match you'd need a 41x30.8mm sensor (49.99deg / 9.32ft).
The closest I'm aware of is the Kodak KAF-31600 31.6MP sensor at 44.2x33.1mm and would yield 53.3deg AOV and 10.04ft FOV.
Then again, a 55mm lens on a KAF-39000 or a KAF-50100 (both 49.1x36.8mm) would offer 58.3deg AOV & 11.16ft FOV, which is pretty darn close (theoretically) to the average macular vision of the human eyeball.

So there ya go, depending on what spin to throw at it, a 55mm "kit" lens could mean anywhere from a "new" 41x31mm sensor all the way up to Kodak's 50.1MP beast.

[janosh]

MF has traditionally included 46mm square "super slide" format, which fits nicely in a 2X2 slide mount (Carousel projector).


I'm not sure but that may be the same as the Baby Rolleiflex's format.


I personally shot thousands of slide duplicates on long roll 46mm E4 duplicating film using a Forox animation camera. Don't recall the usable film area...might be 41X41. It was a beautiful way to duplicate sections of 35mm slides or, for that matter, 120 or 4X5 sheet film. They were ultimately mounted in Wess anti newton mounts, which are still available.


46mm roll film was also very often used in long roll portrait cameras instead of long roll 70mm ( eg Camerz brand).


This is the same format as Hasselblad's super slide back, which used 120 film and wasted the excess. A super slide film cutting punch was available for that.