Aperture

[abraxas]

I shoot nikons in manual mode because I like to push the buttons and spin the little wheels. One thing I've wondered about though, is how come I can't set the aperture to the minimum size?

For instance; one camera I have says the minimum aperture value is f/37. Anyone know why sometimes I can't set it below f/22?

 

[prodigy2k7]

IMO - Just guessing, maybe the lens can only go to 22 but the camera can allow up to 37?

 

[Miaow]

I've found it depends on the lens setting with the canon (kit lens 18-55mm) - to get F36 it has to be on 55mm

 

[davidfromoz]

On my Nikon 18-200VR both the maximum and minimum aperture vary with the focal length (zoom factor).

I'm a bit of a newb here. But conventional wisdom says in most cases you don't want to take the aperture number really high because the image will be degraded. But sadly, if you follow the advice you don't get to spin the wheels as much.

cheers,
david

 

[ScottS]

I shoot nikons in manual mode because I like to push the buttons and spin the little wheels. One thing I've wondered about though, is how come I can't set the aperture to the minimum size?

For instance; one camera I have says the minimum aperture value is f/37. Anyone know why sometimes I can't set it below f/22?

It depends on the lens. The camera has the ability to push the aperture to f/36, but the lens only goes to f/22.

 

[Garbz]

The camera is nothing. It's a piece of software. It all depends on the lens. The design is when you zoom in on a lens with variable aperture like the 18-55 f/3.5-4.5 is that at 55mm the image is 2/3rd of a stop darker. The actual physical dimensions of the aperture blades does not change.

So at 55mm you have the same range just 2/3rd of a stop darker instead of 3.5-22 you get 4.5-37. Diffraction would still limit you quite a bit above f/11 (or f/14 at the 55mm end) anyway, and the images would cease to be sharp.

 

[prodigy2k7]

Ya, but I assume the mathematics on the camera only allows up to F36 maybe?

 

[abraxas]

Thanks all.

 

[Garbz]

Ya, but I assume the mathematics on the camera only allows up to F36 maybe?

Don't assume that. What this would mean is that you would not be able to say take a macro photo at the correct exposure. This isn't mathematics. It's a mathematical formula. The camera is not the limiting factor. Apertures are controlled by the CPU in the lens. When I mount my MicroNikkor f/2.8 it ranges from f/2.8-22 as per normal. But at it's near zoom the camera can set between f/7.1 - f/56. If the camera limited this at f/36 then it would not be compatible with the lens.

 

[prodigy2k7]

ty, i said maybe lol