| | List |
| Subject: | Re: Why is there no DX standard lens? |
| Poster: | Jim |
| Date: | Sun, 25 Feb 2007 13:14:00 EST |
| Related Postings: | 1 2 3 4 5 6 7 8 9 10 11 12 13 |
"Paul Rubin" <http://phr.cx@NOSPAM.invalid> wrote
news:7xhctai1ft.fsf@ruckus.brouhaha.com...
> "Jim" writes:
>> There is no "standard" lens for any format. There is a "normal"
>> lens whose angle of view more or less has the same angle of view as
>> the sharp area of human vision.
>
> I think a "normal" lens has about 45 degrees of coverage because
> that's the simplest to make optically for a given f/ratio. For 35mm
> FF, that's around a 45mm focal length. The film to flange distance on
> a 35mm SLR system is chosen so that the image circle of that 45mm lens
> is about the right size for the film frame. However, with a DX lens,
> because of that extra distance, they need a more complex optical
> design to get the same angular coverage.
No, the flange distance was set to such that the rear of the lens would not
interfere with the operation of the mirror. In the case of Nikon, the
flange distances of the DX cameras and of the 35 mm cameras are identical.
I think that I will go mount my 28-105 zoom on my D70 just for grins. On
second thought, my daughter uses her 28-105 on her D70 with no coverage
problems at all.
Jim
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