Talk:Crop factor

message: I reverted the last 2 of many edits by Acerimusdux, due to an objective error.  My edit summary got truncated; tried to say "shooting from the same position, with same f-number, with the same actual focal length will yield the same depth of field" is objectively incorrect as it ignores COC dependence on format size.  See the depth of field and circle of confusion articles.  Some of the earlier edits I'm not so keen on, either, as they seem to be suppressing the idea of "full-frame" in favor of the more ambiguous 135 film size, which has more than one format. Dicklyon 07:16, 10 November 2007 (UTC)
replies: text: Actually, "full Frame" is the ambiguous term as it originally meant --and to some, it still means-- a 10x8 inch (HxV) studio camera with a crop factor of 1x. 135 has only one size; 36x24 mm. There is no other size for which 135 format means. It refers to the 35mm film in the daylight loadable cassette invented by Kodak in 1939. It is very specific down to the millimeter unlike APS-C (or 120/220 film which has several form factors, which is where the term "crop-factor" originated). Applied Logics 03:18, 31 March 2015 (UTC)
replies: text: Are you confusing "full frame" with "full plate"?  Dicklyon (talk) 05:29, 1 April 2015 (UTC)
thread_title:  Acerimusdux edits 

message: Since the image is effectively cropped, less light is available. Should be 1/form factor², probably a bit dampened by cos^4 law (probably not much, since lenses are built to avoid vignetting). This should (these are my ideas, not read somewhere) act like an additional aperture (cameras do not care since they measure the light anyway). But the additional "aperture" is a crop only, i.e. it does not make the image sharper since the original aperture is responsible. It does however cut a lot of vignetting, fringing etc. that appeear in the outer regions. This means using "analog" objectives on APS-C should result in unchanged central image, less fringing etc but less light and thus potentially more ISO/noise (i.e. F5.6 is really about as dark as F8). May also be a good idea to use "A" mode for fixed aperture because camera may go for ISO 100 and F5. The sharpness is of course reduced by form factor compared to 35mm, since the pixels are simply smaller. --88.74.172.201 (talk) 07:14, 2 June 2010 (UTC)
replies: text: The same amount of light is hitting any given square mm area of the image. Cropping off 99% of an image does not reduce the amount of light hitting the remaining 1%. Yes, 99% less light (assuming even lighting) is now being used overall but the amount of light that hit that 1% of the image does not change. f5.6 on a 135 format lens on a 135 format sensor is still f5.6 on an APS-C sensor with an APS-C designed lens or the 135 format lens. That is why hand-held light meters, whether incident or reflected, do not care what camera one uses, just aperture, film sensitivity and shutter speed. Applied Logics 19:12, 26 March 2015 (UTC)
thread_title:  Aperture reduction 

message: Hey, what about a table with common photography formats, movie formats, and sensor sizes in comparison to 35mm in photography and Academy format movie 35mm? I'm thinking of a table which has 6 columns for each entry: Width, height, diagonal, image area, and area size ratio compared to 35mm and Academy format each as an integer. It'd help people about calculating equivalent focal lengths to achieve identical angle of view. We could also have  in the weblinks, people could look up the image/sensor dimensions here, then enter the values into that calculator.
I'm thinking about one table as described above (6 columns on each entry) for the common sensor sizes such as those at Image sensor format#Table of sensor sizes (keep in mind there's three different aspect ratios when it comes to sensors, 4:3, 3:2, and 16:9!), a second for the most common movie formats (70mm, 65mm, Super16, 16mm, 9.5mm Pathe, Super8/Single8, and Regular8), and a third for the most common photography formats.
Also, angle of view greatly affects not only the amount of how much of your scenery you can capture, but even moreso your perspective. It's why these issues matter so much beyond simply how much moving space the photographer has available at a given location.
You may move back and forth to capture more or less of your scenery, but you'll never be able to do the same as when you're changing your angle of view! Long lenses compress a perspective, wide-angle lenses stretch it, see perspective distortion (photography). That's why 35mm equivalent and crop factor are of such significance in photography and cinematography, people wanna know how to achieve a particular amount or lack of perspective distortion, but focal lengths are by default given for 35mm only. A single line about "BTW, perspective will change, too" just doesn't cut this. --79.193.41.249 (talk) 00:17, 20 August 2010 (UTC)
thread_title:  Comparison aids and perspective 

message: Hi. I started a discussion here  and the conclusion was that the angle of view variation should be put in the Crop factor page. 
Could you tell if the proposal to add the variation formula in this article is ok? Iulian.serbanoiu (talk) 09:21, 9 December 2011 (UTC)
thread_title: Angle of view variation

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