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-   -   LENS APERTURES (https://forums.steves-digicams.com/sony-alpha-dslr-konica-minolta-dslr-sony-slt-77/lens-apertures-104097/)

joee Oct 17, 2006 2:31 PM

mayby somebody can set me straight on lens apertures, lets use for example the 70-210.

f 4.5-5.6

f 3.5-4.5

f4

the only decent 1s are the f 3.5-4.5 & 4, but what puzzles me is why a fixed aperture f4.

the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.

but then there's something about the 3.5-4.5 that when you get all the way out to 4.5 it's no good.

100% confused.

cope Oct 17, 2006 3:04 PM

joee wrote:
Quote:

mayby somebody can set me straight on lens apertures, lets use for example the 70-210.

f 4.5-5.6

f 3.5-4.5

f4

the only decent 1s are the f 3.5-4.5 & 4, but what puzzles me is why a fixed aperture f4.

the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.

but then there's something about the 3.5-4.5 that when you get all the way out to 4.5 it's no good.

100% confused.
Quote:

f4.5 isn't necessarily bad, it's just slower than f4. On the wide end, f3.5 can be better than f4. The f4 beercan is way heavier and longer than the f3.5-4.5, and many who own both say the f4 doesn't produce pictures that are all that much better. Most will admit that they carry the lighter 3.5-4.5 for longer walks. Unless your budget is really tight, don't think about the 4.5-5.6.

JimC Oct 17, 2006 6:22 PM

joee wrote:
Quote:

the way i understand it is if it's fixed then you have no variable depth of field & would be limited to shutter speed depending upon amount of light but yet the f4 is the better 1.
Lenses are rated by their largest available apertures (smallest f/stop numbers). That does *not* mean that you can't use other aperture settings.

You can still use smaller apertures (higher f/stop numbers).

Most lenses can be set to an aperture of f/22 or smaller (a smallest aperture of around f/32 is relatively common with zooms in this focal range).





MINOLTANUT Nov 8, 2006 12:32 AM

constant apr just means it doesnt change when you zoom in........others get darker the closer you try to get........


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