Why 40mm

It only takes a minute to sign up. Connect and share knowledge within a single location that is structured and easy to search. Are these two things by physical limitation or by design? By design long long ago? If by design, by which part's design? By whose design?

It's to do with the backfocus distance, that is, the space between the back of the lens and the sensor. When this distance is greater than the focal length a simple symmetric lens design can be employed. The backfocus distance on a regular 35mm SLR is about 40mm. To make a wide angle lens with a symmetric design the back of the lens would have to be closer to the sensor, which wouldn't leave space for the mirror.

So it has to be further away with a reverse telephoto group stuck on to make up for it. This is known as a retrofocus design. Now you have two lenses in one, instantly increasing the size and weight. There are other factors too, such as the extra corrections required for wide rectilinear lenses due to the use of spherical lens elements.

The larger the aperture, the more glass is required, both for the aperture itself and for the necessary corrections. Tsk, tsk. Looks like a slightly bulging body cap:. You can see her work on Flickr , Behance and her Facebook page. In the video he uses a 40 mm on a Canon 5 D Mk 4.

Or 25 mm on a Canon crop body. You are right about this: if you use the 40 mm full frame lens on a crop body it will behave as a 64 mm lens. But the question was; if you use a 40 mm on a full frame body, which lens would you have to use on a crop body?

Those big lenses fit on cameras that some would say are too big for street photography. Maybe for a prime but nothing beats a And yes, you can still hide in plain sight using it. I am a big 40mm fan on film. It is a 4 element Tessar formula lens and is very sharp and has gorgeous bokeh. This is not only a "fancy" rangefinders forum, and lots and lots of rangefinder and viewfinder cameras from the forties up to the digital days had 35mm to 40 something lenses fixed permanently on them.

It was harder to keep lenses shorter than mm clearing the mirror on the earlier single lens reflex cameras and I think this tended to fix the slightly longer lenses as being "normal".

Here are a couple of examples out of many. The Ricoh is 35mm and the Rollei is 40mm. JDMvW , Jul 16, Perfect lenses on all three, but I did feel like wanting a 85mm sometimes. Could it be a portrait issue?

I'll bet a huge number of shots at 50mm are portraits, and not scenic or action. Anything less than 50 in 35mm format is likely to yield less flattering faces and a little too much depth of field. Even for head-and-shoulders, you really have to get in someone's face. Even in MF, I find a 75mm such as that on my Mamiya 6 just a little too wide for portraits, and the 80mm a little better.

Not being a proponent of "street photography", the 50mm is my normal lens. As Scott mentioned, it provides a good perspective for people pictures and does not introduce the distortion found in close-ups with wide angle lenses.

One lens does not fit all situations and 35mm is just too wide for many applications. I live in the country and use the 65mm Elmar with Visoflex and Bellows more than my other lenses. My 90mm Tele Elmarit has produced some fine portraits and other situations have called for the mm Tele Elmar or mm Telyt. The world is full of subjects for photography and there is a very valid reason that Leitz made a wide range of focal lengths that could be used with their rangefinder cameras.

Popular rule of thumb is that "normal" focal length is equivalent to the diagonal on your negative Why did 35mm and 50mm become so popular? I think it's historical accident On the RD-1s, which has a crop factor of 1.

On the M8, a 28mm is a 37mm equivalent. I 5mm a big deal? Sometimes I think people worry about focal length too much. For practical purposes, a 35mm and 40mm are not materially different. The signature, sharpness, and flare performance of the individual lenses are probably more important I'm surprised no one has linked yet to Mike Johnston's well-known article, "Why 40mm? A Review of the 40mm Sigma Art. Premium Photography Tutorials Check out the Fstoppers Store for in-depth tutorials from some of the best instructors in the business.

Perfecting the Headshot. Log in or register to post comments. Anonymous - February 20, Couldn't agree more with this assessment which is obviously a personal preference. Thanks for sharing. Campbell Sinclair - February 20, sexy time with canon Dariano Bisotnik - February 21, Eric Robinson - February 22, I enjoy dropping by fstoppers now and then, nearly always interesting stuff on offer.