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01-22-2015, 04:26 PM   #1
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Questions about medium format!

1. I heard that there is FF for 645. I thought 645 is crop and 67 is FF medium camera. Is there any size comparison?

2. Why Pentax lens category for 645 wide lens have two 25mm lens? I don't see DFA version at all.

01-22-2015, 04:43 PM - 1 Like   #2
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QuoteOriginally posted by sunshine7913 Quote
1. I heard that there is FF for 645. I thought 645 is crop and 67 is FF medium camera. Is there any size comparison?

2. Why Pentax lens category for 645 wide lens have two 25mm lens? I don't see DFA version at all.
Full frame is 24x36mm. 645 digital is 44x33mm. 645 film is ~60x45mm. 67 is ~56x70mm. Digital sensors that match the size of medium format film aren't mass-produced at the moment, but you still get a very large sensor with digital medium format.

Pentax ended up releasing a DA version of the 25mm with the same optics but a longer hood because the hood on the DFA version was too small, failing to optimally reduce flare on the 645D/Z.

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01-22-2015, 04:47 PM - 1 Like   #3
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You may get more complete answers from others, but keep in mind that all digital 645 cameras are a crop from 645 film - especially the Pentax and the new models from Phase One and Hasselblad which use the same senor as the 645Z. Phase One, for example, has a number of sensors that are less of a crop - including one or two sensors that are a fairly minimal crop.

Here is a size comparison, though you can find more comprehensive information comparing different brands on Wikipedia:

http://www.phaseone.com/Camera-Systems/IQ2-Series/IQ2-Specifications.aspx


The IQ250 uses the same sensor as the Pentax 645Z. The IQ250 certainly has its advantages, but it costs a lot more than the Pentax body - or for that matter a complete Pentax system! Note that while Phase One calls the "Lens Factor" 1.0 on the larger sensors, they still aren't quite as large as the frame of 60x45mm on film (let alone the larger frame that same film gives in a 67 camera).

Last edited by DSims; 01-22-2015 at 04:58 PM.
01-22-2015, 04:51 PM - 1 Like   #4
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QuoteOriginally posted by sunshine7913 Quote
I thought 645 is crop and 67 is FF medium camera
You are mixing digital parlance with film sizes. There are at least 6 medium format frame sizes for film and to say that 67 is FF is not correct.

Just to clarify an above point, the 645 film frame is 41.5mm X 56mm and the 6x7 is 55 X 70mm


Last edited by desertscape; 01-22-2015 at 04:57 PM.
01-22-2015, 04:58 PM   #5
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*"Full Frame" is an ambiguous term and I wish it would never have become prevalent. Most seem to interpret it as 24 x 36 mm, but many other formats can be claimed to be FF as well as desertscape hints, such as the 6x7, 645, and 6x6 film formats based on 120/220 roll film.
01-22-2015, 05:16 PM - 1 Like   #6
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I shoot 6x9 so the only thing bigger with 120-film is panorama cameras.
01-22-2015, 10:18 PM   #7
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QuoteOriginally posted by VisualDarkness Quote
I shoot 6x9 so the only thing bigger with 120-film is panorama cameras.
There used to be 6x12 cameras, which might be considered semi-panoramic or just wide.
01-22-2015, 10:30 PM   #8
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QuoteOriginally posted by hsteeves Quote
There used to be 6x12 cameras, which might be considered semi-panoramic or just wide.
Well, those are most often found under "panoramic" so I consider them to be that. Wiki says this about panoramic:
"This generally means it has an aspect ratio of 2:1 or larger"

All in all 6x10 or 6x11 might be biggest non-panoramic medium format available, after that you hit stuff mostly considered large format.

01-22-2015, 10:57 PM   #9
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QuoteOriginally posted by sunshine7913 Quote
Why Pentax lens category for 645 wide lens have two 25mm lens? I don't see DFA version at all.
The SMCP-D-FA 25mm f/4 ASPH ED is presently only available for the Japanese market - Originally it was made for the worldwide market, but Pentax re-designed the lens to suit the smaller 44X33mm sensor in the 645D and 645Z.

QuoteOriginally posted by Ole Quote
*"Full Frame" is an ambiguous term and I wish it would never have become prevalent.
Which is why I use the term "FX format" or "24X36 format" But some people get hung up about me using the term "FX format" as being a Nikon centric term.
01-26-2015, 08:04 AM   #10
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QuoteOriginally posted by desertscape Quote
Just to clarify an above point, the 645 film frame is 41.5mm X 56mm and the 6x7 is 55 X 70mm
And if you are going to get down to the millimeter of the the actual frame projected on a 120/220 roll of film, that will vary from one manufacture to the next.
01-26-2015, 09:30 AM   #11
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"Full-Frame" and "Crop" are used in relation to the film size that a camera is based on, at least where applicable. For instance, if you are shooting 645 lenses on a native-mount camera whose sensor doesn't cover the full image circle, that would be a crop sensor, yet nowadays we have many camera systems that were designed from the ground up for a specific sensor size with no ties to any film equivalent.

As an example, the Leica S can't really be called a crop camera, because it's not possible for the sensor to be any larger, Leica designed their lenses to cover 30x45mm from the start. The fact that you can adapt other 645 lenses to the S is purely incidental to it having an unusually short flange distance, thanks to the 2:3 image format, and consequently smaller mirror. Similarly, micro four-thirds cameras aren't crop cameras compared to 35mm or APS-C, because they don't use the same lenses, they are a self-contained system.

Medium format film is just a contiguous roll and the size was set by the camera used, so in this case full-frame and crop can simply refer to what percentage of a given camera's imaging plane is used, especially considering that different medium formats required different bodies and lenses. 645 is a crop of 6x7 - but only if you shot it 6x7 and then cut the film.
01-26-2015, 10:58 AM   #12
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QuoteOriginally posted by hsteeves Quote
There used to be 6x12 cameras, which might be considered semi-panoramic or just wide.
There still are 6X12 and 6X17 cameras available for sale (film cameras that is)

And I agree with the poster who lamented the use of the term full frame; not only is it confusing in "normal" cameras but when looking at other formats. micro 4/3 is a full frame camera as is a 8X10
01-26-2015, 06:40 PM   #13
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And, rather ironically, the Leica cameras that pioneered the 35mm format were initially referred to as double frame since their negative was twice as large as the standard movie frame. By that standard APS-C is almost full frame (25.1 x 16.7mm vs 24.9 x 18.7mm).
01-26-2015, 11:36 PM   #14
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QuoteOriginally posted by redrockcoulee Quote
There still are 6X12 and 6X17 cameras available for sale
A colleague of mine works with a 6X23 format camera from Gilde - sadly only a handful of these cameras were made but they could change format from 6X6 to 6X17 with a very clever magnetic masking system. The 6X23 format option was only available with an optional film back adapter.
01-27-2015, 10:15 AM   #15
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QuoteOriginally posted by Digitalis Quote
A colleague of mine works with a 6X23 format camera from Gilde - sadly only a handful of these cameras were made but they could change format from 6X6 to 6X17 with a very clever magnetic masking system. The 6X23 format option was only available with an optional film back adapter.
I was not aware of that format, that is truly panoramic.

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