Why is focal length measured in mm




















It'll walk you through getting a good exposure, how to set your camera up to get crisp sharpness, composition, and more. Read the photo basics series here.

I love this article! Truly excellent and easy to read. I study photography at Chicago Photography Academy and found this extremely helpful.

Thank you so much for explaining focal length in so much detail! I am a new DSLR owner crop sensor so this article was super helpful for me.

Your work is amazing. Thank you. Very affordable fast primes. This is really a great information for beginners. Today I learnt something new and informative. Thanks so much, keep posting. Is it true that when using a crop sensor your 1.

In other words, are your f stops all doubled? I pick the lens in my kit that I know would work best for my needs and shoot. Do I really need to know all this? Landscape photography 10mm to 18mm Full body portrait of a person 24 to 45mm Headshot 55 to mm Night photography 10 to 18mm Close-up photography or macro photography 70 to mm Wildlife photography mm to mm General lens for shooting family and kids 35 to 90mm Outdoor sports photography to mm.

Given the following suggested focal lengths for different situations above, what is the ideal distance between the photographer and the subject? I am new into photography, I am sorry for my noob question. Thank you for this interesting article. You mentioned that there is no advantage of full frame sensor over the crop sensor.

Now what about shooting in low light and the impact on the noise level? Skip to content. The focal length scale shows that this lens can go as wide as 10mm and as long as 24mm zoomed in. Right now, it is set at 18mm. Almost all lenses have a scale like this on them. What is focal length? The inner rectangle is the photo taken with a Nikon crop sensor DSLR, the full outer picture is taken at 18mm as well, but with a full frame camera.

In this example with my lovely wife, I first stood VERY close to her and shoot at 10mm, then stepped back and zoomed in for each consecutive shot. Scoot back and zoom in when shooting portraits! Using a Proper Focal Length for Portrait Photography Wider lenses show more distortion unnatural bending of objects in a picture—especially around the edges of the frame.

Landscape photography 10mm to 18mm Full body portrait of a person 24 to 45mm Headshot 55 to mm Night photography 10 to 18mm Close-up photography or macro photography 70 to mm Wildlife photography mm to mm General lens for shooting family and kids 35 to 90mm Outdoor sports photography to mm Now that you've read through this handy cheat sheet of focal lengths for different situations, you should really consider checking out my free lens finder.

Notice the HUGE difference between 10 and 15mm, but the tiny difference between and mm. In fact, the and marks are so close together that you can't even tell them apart on this web-sized version. As your focal length gets longer, the difference in field of view is less of a change. That's the front of my house, by the way. How Differing Focal Lengths Affect Field of View There is one last thing you need to understand about focal length in order to have the basics under your belt. Quick Links.

Peter Mortensen 6 6 bronze badges. B 1, 3 3 gold badges 21 21 silver badges 31 31 bronze badges. What would you expect a length to be measured in? One obvious reason is that the scientific world generally not always uses SI even in countries like the US and UK where it is not used in otherwise general practice. Lens making is very much science, so no surprise there. Perhaps a better, more complete question is "how is focal length measured?

I see a certain dismissiveness in this thread from some people. I would like to state that I think this is an important "History of photography" question and the comment by mattdm below is an important addition.

So, I would say the true answer is: We settled on mm due to a combination of SI units and convenience in terms of magnitudes though historically different units have been used. I still see ebay listings for 2. Lol, this is absurd. The moment this question pop-up on the home page of the community I thought "Oh god, it's been ages I've wanted to ask this, too".

Opened it, read the comment, and seriously I was thinking "Are they joking?? Then I realized nobody understood the sense of the question People, you cannot imagine how many times people asked my why the field of view is in mm and not in degrees, and how many time I had to resort to "Tradition. Don't ask" :-D — motoDrizzt. Show 3 more comments. Active Oldest Votes. Improve this answer. Diverging concave lenses also have a focal length, but it's negative, since it measures the distance to the apparent origination point behind the lens that the diverging rays appear to come from.

Lenses have been measured in other units, but that was very long ago mostly 19th century. Most I saw that was not mm was cm. Add a comment. Olin Lathrop Olin Lathrop Matt Grum Matt Grum k 5 5 gold badges silver badges bronze badges. The other logical way to characterize a lens could be by the FOV angle it produces. Kaushik Ghose Kaushik Ghose 4 4 silver badges 14 14 bronze badges.

In the case of portraiture a telephoto allows the photographer to take the photo at a distance that does not intrude upon the subject. These lenses provide a good range for wildlife and sports photography where the photographer is limited as to how close they can get to the subject.

Close-up photography uses a specific range of lenses that allow up to reproduction. These lenses allow the photographer to focus very close to the subject and reproduce them at a life-size ratio on film or an imaging sensor.

These lenses are popular for subjects such as flowers, insects and small products. By clicking Sign Up, you are opting to receive educational and promotional emails from Nikon Inc. You can update your preferences or unsubscribe any time. Search Articles. Glossary Off On. What is Lens Focal Length Focal length, usually represented in millimeters mm , is the basic description of a photographic lens.

Standard Lens FX format approx. Telephoto Lens FX format approx. Super Telephoto Lens FX format approx. More Like This More articles like this. Article Collections.



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