Nikon D50

[ems3369]

I have a nikon d50 and I am a little new to photography. My question is. When using any of my lenses, Nikkor 18-55, Nikkor 28-80, or Tamron 28-105 I set my f stop to the highest setting on the lens then adjust through camera. When I am at the lowest zoom setting the my f stop will be at the lowest if that is what I set it at, but when I move to the highest zoom then the camera will not let me use the lowest f stop setting. I am looking for a very blurred back ground on my portraits. ex. My 28-105 lens has f stop from 4 to 22. When zoom is set to 28 the f stop can be set to 4. But when zoomed to 105 the f stop will only go to 5.8. Can someone explain this and can it be changed in camera? If so how because I can't find it. Or at least explain why the camera and lenses do this. Thank you.

 

[MrJ]

Hi,

I'm a newbie with a D50 too (just got it yesterday!).

From my understanding the maximum apperture setting changes with the amount of zoom. So for the 18-55mm, for example, can get down to f/3.5 at 18mm but only f/5.6 at 55mm.

 

[epp_b]

See: variable aperture zoom.

There are constant aperture zooms as well, but they're honking expensive.

 

[ems3369]

Thank you for that information. Guess if I want a good fixed focus lens with multi aperture settings for portraits I will have to go with the 50mm f1.8 lens I keep reading about. I am going to do some test shots with the other two lenses tonight on a model and see how those turn out. Thanks again to all that post.

 

[CrazyCanuck]

Thank you for that information. Guess if I want a good fixed focus lens with multi aperture settings for portraits I will have to go with the 50mm f1.8 lens I keep reading about. I am going to do some test shots with the other two lenses tonight on a model and see how those turn out. Thanks again to all that post.

Fixed focus, is not what your after, your after a fixed focal length lens also called prime lenses. The 50mm f/1.8 is a really good cheap portrait lens, but for a bit more, if your going to be doing a lot of portrait work, I would personally suggest the f/1.4 version. It can blur the background even more(shallower depth of field), and its incredible in low light.
Not sure about the 35mm f/1.8 DX that came out, but its also a prime. It might be to short for portraits though, and not give a big enough working distance.