Talk:35 mm equivalent focal length

Untitled
I don't think that "sensor size specifications typically refer to approximately 1.5 times the actual sensor diagonal" is useful information. The reference for that actually says "There appears to be no specific mathematical relationship between the diameter of the imaging circle and the sensor size, although it is always roughly two thirds." I would suggest something like "Image sensor format specifications such as 1/1.8" should not be used in the formula above. Instead the actual sensor size needs to be found, which does not have a mathematical relationship to the sensor size specification" (but this needs writing more clearly) Danio (talk) 14:16, 26 February 2008 (UTC)

Derivation of conversion forumulas
For completeness, this is the derivation of the conversion formulas. This gives the numbers 33.8 34.6 and 46.1 48.0. Han-Kwang (t) 13:55, 17 February 2008 (UTC)
 * Define aspect ratio a=w/h, hence d=w*sqrt(1+1/a^2). (4:3 => a= 1.25 1.333; 3:2 => a=1.5)
 * Define W=36 mm and D=sqrt(24^2+36^2)=43.27 mm, the diagonal of 135-film images
 * Diagonal-based definition: f35 = f*D/d = f*D/(w*sqrt(1+1/a^2))
 * Width-based definition: f35 = f*W/w = f*W*sqrt(1+1/a^2)/d
 * Drono pointed out to me that I made a mistake. I corrected the numbers; see strike-through above. Han-Kwang (t) 11:08, 20 December 2008 (UTC)

Good work
Good work an making this article - I think it's good that the term "35 mm equivalent focal length" can now be linked to something.

Would it be an idea to include Image:SensorSizes.png on this page, or would that make it more confusing? (My opinion is colored by the fact that I made the first version of that diagram, so I'd like to see it all over the place :-)

--RenniePet (talk) 16:17, 17 February 2008 (UTC)


 * I think the article could use an image, but I'm not sure that SensorSizes.png is the best one to illustrate this. crop factor has a couple of useable images. Han-Kwang (t) 19:44, 17 February 2008 (UTC)

Renaming article "35 mm" to "35mm"
Just noticed that someone renamed this article a couple of days ago, changing all occurrences of "35 mm" to "35mm".

I think that was a big mistake.

From the Wikipedia Manual of Style: "Values and unit symbols are spaced (25 kg, not 25kg)." Manual_of_Style

If there are no serious (and they'll have to be pretty serious) objections I'll rename it back again tomorrow. --RenniePet (talk) 15:05, 26 February 2008 (UTC)


 * I agree with the revert to "35 mm" from "35mm", but the title can be confusing for people accustomed to the metric system. There is nothing that measures as 35 mm on a Full-frame camera sensor. The term "35 mm format" is pretty much an american term for what in many other countries is called something else. The term "35 mm format" comes from the fact that Full-frame film cameras use a film with a width of 35 mm, but digital cameras does not use that, of course, so there is nothing "35 mm" about a digital Full-frame camera. The image size of a Full-frame camera is 24 mm × 36 mm regardless of medium.


 * I propose that the title is changed to "Full-frame equivalent focal length" with a redirect from the current title. Amandashusse (talk) 12:36, 9 July 2019 (UTC)

Comparison aids and perspective
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 (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. --79.193.41.249 (talk) 00:24, 20 August 2010 (UTC)

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