Linked Questions

15
votes
7answers
8k views

What is a normal lens?

I've heard people call 50mm lenses "normal lenses". For a lens to be considered normal, does it have to be exactly 50mm or is there some leeway? Does the normal focal length depend on crop factor of ...
8
votes
2answers
3k views

Is it normal for focal length to change while focusing?

When I change the focus distance on my Pentax 55-300mm lens, the focal length appears to change. More specifically, the lens appears to zoom in as I focus towards the minimum focusing distance. This ...
5
votes
2answers
19k views

How can I calculate focal length from a photograph?

I posted this question over on Stack Overflow, but someone suggested this site might be of more help to me. I'm doing a college project where I'm trying to calculate the focal length of a camera ...
12
votes
1answer
8k views

What are the different sensor sizes used in DSLRs?

What do the different sensor size names used by Canon mean? There's APS-C, APS-H and full format? What are the standards used by Nikon, Pentax, Sony, Olympus, Panasonic, and others? What are the ...
5
votes
2answers
5k views

Why is the sensor size small in D3100 as compared to D3000?

I thought Nikon D3100 must be more advanced than D3000 (because of the higher number and the increased price). But, the D3000's sensor size is 23.6mm x 15.8mm and the D3100's sensor size is actually ...
1
vote
2answers
4k views

What size is the Canon 550D sensor?

I have these options: 35 mm film Medium Format Canon 10D Canon 30D Canon 300D Canon 5D, 5D MKII Canon 450D, 1000D Canon 50D Which is the closest to 550D?
4
votes
3answers
12k views

How can I calculate vertical field of view from horizontal field of view?

I have an Axis M1011 (specs available here), which I need to find the vertical field of view. The online specifications tell me the horizontal field of view is 47 degrees, and the image size is ...
5
votes
3answers
2k views

Why aren't the electronic bright lines for framing in the X-Pro 1 viewfinder more accurate?

The Fujifilm X-Pro 1 has a viewfinder which can switch between an electronic mode and an optical mode with an electronic overlay. One of the key features of this overlay is a "bright frame" — the ...
13
votes
3answers
523 views

How to test what aperture is actually used?

It seems odd to me that Canon EF 100-400mm f/4.5-5.6L does away with a front element of only about 63 mm, as reported by @jrista - which would be enough for only f/6.3 at 400mm, missing the spec by ...
1
vote
2answers
16k views

How can I know the focal length and sensor size of my webcam?

I have this webcam: QHM495LM WEB CAMERA and I need to know its focal length and its sensor size, but in the specs of the webcam, it only gives me this information: • Inbuilt sensitive microphone and ...
4
votes
3answers
1k views

Why isn't my computation of the actual size of an object in a photograph matching the expected value?

Let's say I have a full frame camera (Sony A7) with a 50 mm lens (Canon FDn 50mm f/1.4) mounted on it. At a given object (a plane) distance I should be able to compute the size of the image in real ...
3
votes
2answers
436 views

How to compare the speed of lenses taking transmission into account?

When comparing the speed of two lenses, you almost exclusively hear about the maximum aperture. This of course makes sense, since at a certain lighting condition, a larger aperture in general allows a ...