Not Your Everyday Banana

by Bart Arondson

submit your photo


Hall of Fame
View past winners from this year

Please participate in Meta
and help us grow.

Tag Info

Hot answers tagged

21

Summary A zone plate is a way of focusing light, like a lens, but using Fresnel diffraction instead of refraction. This is cool from a theoretical point of view, because it demonstrates the wave nature of light. And it's cool from a photography point of view, because the images produced have a unique glow, with a impressionistic almost-painted look. If ...


5

One option is to use a zone plate optic with a wide-angle converter lens in front. An off-the-shelf solution is Lensbaby's zone plate optic + wide angle 0.6× or super-wide angle 0.42× conversion kit. Since the optic gives a focal length of roughly 55mm, the results will be about 33mm or 23mm. Examples are available on Lensbaby's site with the zone plate ...


5

They're an alternative to lenses. Basically using diffraction instead of refraction to focus light. They're very common in some forms of lithography when dealing with wavelengths that glass blocks. You can actually think of a single pinhole as a degenerate case of a zone plate.


4

Focal length from field of view is really simple and covered in my answer to What is “angle of view” in photography?. The formula for field of view in degrees is 2 × arctan( half sensor size ÷ focal length). Because this formula is so simple, I see no reason for the calculator you're using to be wrong (and it indeed seems to match my validation). And, yeah, ...


3

I really like the idea but in my opinion anything can go wrong with a 4 hour exposure. Firstly, you may be right about the sensor. It might overheat, although opinions are divided on this issue. CMOS sensors are really energy efficient and I've never experienced sensor overheating while taking pictures or recording videos. However, my longest exposures were ...


2

An 18mm focal length does indeed yield an horizontal Field of View (FoV) of 89°- if it is projecting onto a FF sized 36 x 24mm sensor. In the case of the Sony NEX, the smaller APS-C sized sensor (23.4 x 15.6mm) means a plate placed at an 18mm focal length (the E mount flange focal distance) will yield an FoV of around 67°. The new Sony α7 and α7R are Sony E ...



Only top voted, non community-wiki answers of a minimum length are eligible