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Old May 17, 2005, 12:50 PM   #11
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Sort of,
The only lenses with a fixed f-stop that I know of are the mirror lenses.

All the other ones (either variable like the F4-F5.6, or constant like an F4) can be adjusted from their whatever their maximum is at a set focal length on down to F22 or F32 depending on the lens.

It is fairly simple:
  • Each move on the shutter dial either halves the amount of light recorded or doubles it. [/*]
  • Each move on the aperture dial either halves the amount of light recorded or doubles it. [/*]
  • Each move on the ISO speed dial either halves the amount of light recorded or doubles it.
Changing
[/*]
  • ISO also affects noise/grain/detail recorded [/*]
  • Aperture affects Depth of field [/*]
  • shutter speed, affects motion effects

    :cart: Simple as mud? :idea:

    Peter.[/*]
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Old May 17, 2005, 1:02 PM   #12
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Do you mean they are slow light gathering wise, or slow operating?

The tamerons do not have ultrasonic drive, so they operate slower that the Canons with a ring USM or Sigmas with the Hypersonic drive(same thing).

They operate at about the same speed as normal Canons/Sigmas with either a normal drive or the stepper usm drive(a can motor driving gears in the lens).

Peter.


Quote:
Originally Posted by zwdb08
[b]Tamron mentioned above but it seemed slow at 300mm and wa strying to find one a little quicker but they all seem about the same. Thanks Bill b
[/quote]
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Old May 17, 2005, 2:16 PM   #13
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Let me add something to this thread:

To effectively stop action you want shutter speeds of 1/500 or better. 1/250 will still have some blur to them. Now, if your primary purpose for the lense is shooting sports in a non-college or non-pro gym (by that I mean college and pros have good white light and high school and below generally do NOT) then you are going to want a lense capable of 2.8 at the focal range you will be using. You MAY be able to get by with a f4.0 lense using ISO 3200. But if you want to stop the motion (which usually means 1/500 on fast moving objects) then I think you want 2.8. So, in a nutshell - if you are going to be in the stands and want to stop the motion you need a lense that can shoot at f2.8 at a focal length of about 200mm (that's the lense itself - not accounting for the crop factor of your camera). I'm going to assume you can get good enough seats to make 200mm work. If you are shooting from the floor, you may be able to get by with less reach - but you're still going to want the 2.8. So a recommendation would be the Sigma 70-200 2.8 EX (I'm not sure what the Nikon equivelent would be). I would not recommend any lense that was going to be 5.6 or worse at 200mm for shooting sports indoors. 4.0 may be acceptable but is not optimal. Ideally, people who shoot a lot of indoor sports use fast primes (1.8 or 1.4) - but if you went that route you have to make sure you have the proper lenses for where you will be located (i.e. if you are on the floor under one of the baskets and have a 185mm 1.8 prime you will be too 'tight' for shots at that basket - you would likely need a 50mm or 70mm prime). Hope this didn't confuse your question too much
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