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03-01-2010, 01:49 PM   #1
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fov format comparison graphic

I don't have any 645 lenses but stumbling across an ebay sale and subsequent forum thread discussions, I wanted to approximate the fov of the three formats; 645, 35mm and APSC. I'm using 'crop factors' of 1>1/2>1/3, (105mm MF = ~52mm on 35mm film =~34mm on APSC) relative to the order above. I know it's approximate but this is just a quick and dirty test. I searched google and the forums, and nothing came up, so I thought I'd give it a try. Is the picture below representative of the fov comparison between the three formats, given the initial 105mm lens on the Pentax 645 pic I used for this example? (or is there a link to a more accurate pic somewhere?)



03-01-2010, 06:50 PM   #2
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Great graphic! And I'll remind readers that the smallest rectangle, the APS-C size, is the same size as half-frame 35mm, and the same size as classic Hollywood cinema (turned horizontal). Yes, all those big-screen movies in pre-70mm days were projected onto those big screens from that little frame. (Smaller, actually, since the frame also included an optical soundtrack.)

Now, shrink that APS-C frame by half, and you've got the frame size of 110-format film, and the Olympus 4:3 digital format. Depending on which Pentax camera you have, there are 6 or 10 or almost 15 megapixels on that APS-C sensor. With 4:3, there are 10 or 12 megapickels on a sensor half that size. It gets a little crowded there, inherently a bit noisy.
03-01-2010, 10:29 PM   #3
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Assuming you were using the same focal length on all three cameras, yes. If you used the three different focal lengths listed, they would all show about the same FoV, the largest area.

And a better comparison of focal lengths would be 80=50=32 or 105=65=43 to get the same FoV.

Three things you might look at:

Image sensor format - Wikipedia, the free encyclopedia

Lens Reviews (FoV visualization tool)

FOV Calculator
03-01-2010, 10:56 PM   #4
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thanks!

Thanks Rio and W;

Thanks for the kind words, Rio!

W: I didn't think to google Wiki as that page has the idea I was trying to wrap my head around, though I think using an actual picture like I did says it better.

Thanks also for the other links!

03-02-2010, 02:01 PM   #5
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apples, oranges, pomegranites

QuoteOriginally posted by WJW Quote
Assuming you were using the same focal length on all three cameras, yes.
I think that was the point -- to show what happens with a single focal length, at the same distance, on different size frames. The perspective, the relationship between objects seen, remains the same. From a single vantage point, smaller frames just take smaller slices of the overall scene.

In practice, photographers change position and/or focal length to fit the desired scene-slice to the available frame. Doing so changes the perspective. A wide lens at close distance will barrel-distort the picture. A long lens at long distance will flatten the picture. And if (in the example) all three cameras used appropriate lenses to fill their frames, the smallest sensor must necessarily record MUCH less detail than the largest.

I want a 645D, not an m4:3 !!! (More stuff to schlep around. Groan.)
03-02-2010, 05:38 PM   #6
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QuoteOriginally posted by RioRico Quote
I want a 645D, not an m4:3 !!! (More stuff to schlep around. Groan.)
I want a cheap digital back for my RB67 that actually covers 6x7. Now that would be a camera!!
03-26-2010, 01:50 AM   #7
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bump

For anyone with questions about (shudder) Crop Factor aka FOV (Field of View), see the picture at the top of this thread. 645 vs FF vs APS-C. To see is to know.
03-26-2010, 01:59 AM   #8
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QuoteOriginally posted by RioRico Quote
Now, shrink that APS-C frame by half, and you've got the frame size of 110-format film, and the Olympus 4:3 digital format.
The 4:3 is half the size of 35 mm cameras, not APS-C.

03-26-2010, 02:28 AM   #9
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QuoteOriginally posted by flyer Quote
The 4:3 is half the size of 35 mm cameras, not APS-C.
are you sure about that?
FF = 24x36 roughly
APSC = 18x24 -//-
4:3 = 14x18 -//-

correct me if I'm wrong
03-26-2010, 02:31 AM   #10
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QuoteOriginally posted by flyer Quote
The 4:3 is half the size of 35 mm cameras, not APS-C.
35/FF: frame is 36x24mm, diagonal is 43.3mm, area is 864mm^2
APS-C: frame 25.1x16.7mm, diagonal 30.1mm, area is 419mm^2 (49% of 35/FF)
4:3: the frame is 17.3x13mm, diagonal 21.6mm, area 225mm^2 (26% of 35/FF)
In area, APS-C is 1/2 of 35/FF, 4:3 is 1/4 of 35/FF. Those are the numbers I find.

For comparison, with 35mm half-frame (35/FF) and 110 (remember the Pentax 110 SLR?):
35/HF: frame is 24x18mm, diagonal is 30mm, area is 432mm^2 (50% of 35/FF)
110: frame is 17x13mm, diagonal is 21.4mm, area is 221mm^2 (26% of 35/FF)
APS-C is virtually identical to 35/HF and 35mm cine. 4:3 is virtually identical to 110.
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