Linked Questions

-3
votes
1answer
1k views

How does focal length determine lens quality? [duplicate]

What does an 18 - 50 mm lens mean? Are those numbers the first focal length and second focal length? How do you use this parameter to judge what kind of lens to buy? Does more equal better?
1
vote
3answers
279 views

Is focal length internal or external? [duplicate]

I just wanted to check because I've encountered various distinctly different assertions. I was originally taught that focal length referred to the optimum distance from subject| ←→|lens, where ...
83
votes
6answers
39k views

What is “angle of view” in photography?

I read on the Lens Buying Guide @ neocamera: Focal-length determines the angle-of-view seen through a lens for a given sensor-size. With a full-frame sensor a lens gives the same angle-of-view ...
64
votes
7answers
395k views

How do I convert lens focal length (mm) to x-times optical zoom?

What is the rule to convert the 'mm' notation to the 'optical zoom' notation? I searched a bit and found this one: optical zoom = maximum focal length / minimum focal length For example a 18-55mm ...
8
votes
2answers
4k views

How to zoom with Canon 77D with Canon 50mm 1.4 lens?

I've just bought this camera and the lens, and I feel so silly; I don't know how to zoom. Do you know how? When I turn it on it seems to be zoomed and I would like to zoom out.
18
votes
5answers
11k views

How does changing focal length affect depth of field?

I'm curious about how my "area of acceptable focus" changes when the focal length of the lens I'm using changes as I zoom (or switch lenses). In particular, I'd like to know how the front & back ...
13
votes
3answers
16k views

What is the technical difference between focus and zooming?

This may look like a silly question but I don't know what the difference between zooming and focusing is. Zooming in will usually let me have fewer subjects in the scene while zooming out will allow ...
12
votes
4answers
4k views

How do manufacturers get to high (83x) zoom levels on hybrid cameras?

Obviously the biggest hybrid zoom on the market (Nikon Coolpix P900 I think) does not range from actual 24 mm to 2 meters in physical length, but what kind of optical systems do manufacturers use to ...
4
votes
3answers
72k views

What mm lens for distance shots?

If I am looking to take landscape and wildlife shots and some of those shots being from a decent distance what mm lens would I need? I am not sure what else I should be adding here, I am just looking ...
5
votes
3answers
8k views

What does the millimeter measurement of a macro lens mean?

I understand that the millimeter measurement on a lens is, for lack of a better term, how far it can "zoom" in or out, but what about macro lenses? What does the millimeter measurement signify? How ...
12
votes
2answers
3k views

When I use FX lenses on a DX camera, does the focal length or minimum aperture change?

If I put a Nikkor 35mm f/2 FX lens on a DX camera, is it still 35mm f/2, or has the effective focal length or minimum aperture changed, because it is being used on a smaller format than what it was ...
4
votes
9answers
1k views

How can I explain focal length to someone who isn't into photography?

Context So my friends and family are curious about how far my lens can reach. I usually explain with focal length and show them a few pictures. Question Is there any easier way to explain what ...
5
votes
3answers
3k views

Is the kit lens focal length specified for APS-C or FF?

I have the 18-55mm kit lens for my Canon 50D and was wondering if they're still specified against full frame 1:1 crop? Would my 18mm actually be 1.6x? I ask because I doubt anyone with a full frame ...
1
vote
3answers
6k views

How far can a Nikon P900 focus?

A Nikon P900 has an effective focal length of 2000mm. What's the farthest away that I could get an object in focus with it?
2
votes
3answers
3k views

What do the F and f numbers written on lens mean?

On this particular lens rim is written "F:2.6 f=3.8mm". What does it mean? Focal point 3.8 mm and aperture 1/2.6 of the focal point ???

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