Canon or Tamron?
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30-10-10, 06:32 PM
Join Date: Sep 2009
Originally Posted by
I am considering buying either the Canon EF 28-135mm or the Tamron 28-75. I don't fully understand the Tamron in that it is f2.8 full time. I acknowledge this could be beneficial in low light but as there is no image stabilisation on this lens exposure times will be required to be fast. My question is this. If it is f2.8 full time does that mean that the focal length is permanently short so taking a shot for example of a group of people, or a landscape, the shot will have more out of focus areas than a lens that stops down? Does the camera compensate for this? I hope this doesn't sound elementary (it probably is to the informed) but I genuinely can't understand this point.
When a zoom lens is described as having an F stop aperture that is "full time" it means the lens can shoot at that specified value throughout the whole of it's zoom range. It doesn't mean that it has to, or can only shoot at that value. Any aperture size, beyond f2.8 in this case, can be dialled in at any time. You can choose what aperture you want, and set the variables of the shutter speed (time) and ISO (sensitivity) accordingly, depending on the amount of light available.
AMK1977 is more eloquent than I and can think and type a lot faster than me too.
Last edited by rbarry; 30-10-10 at
. Reason: Took too long to give my reply before someone else gave a better one!
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