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Originally Posted by imcarm I'm sure I read somewhere that teleconvertors need to be used between 100mm and 500mm?
So as SSB stated the 28-75 might be too short. (You could always test one out in a camera shop though) |
Dunno where you read that but I use a 2x TC with my 70-200 f/2.8 and I've even seen paps use 2 2xTC with this lens. The ability to use a TC with a lens isnt governed by the focal length or even the apeture (you can always manual focus after all) but how rear element of the lens moves. If the rear element extends beyond or is flush with the lens mount at either minimum or maximum zoom then it can't be used with a TC as the front element of a TC slots inside the lens it's attached to. If you do attach a TC to such a lens then at best you'll find the lens wont even attach to the TC, at worst you'll try and zoom and....SMASH!
ALWAYS check the compatibility of your lens with a TC before you fit it it.
If you do buy a TC third party ones are a lot cheaper BUT it is always advisable to use the TC from the same manufacturer as the LENS you are using (not the body as previously mentioned although an all Canon or all Nikon body, lens, TC combination is always a good idea). The reason for this is that a Canon TC that is stated as compatible with the relevant Canon lenses WILL be compatible but no gurantee can be made that it will definitely be compatible with a Sigma or Tamron lens even if they are ones that are listed as being compatible with the Sigma/Tamron TC's, it probably will be but do you really want to risk the SMASH scenario? Another reason is that, in the case of Canon L lenses anyway, is that the Canon TC's have a better 'dust seal' that is designed to fit the Canon L lenses dust shield too, something that would be lost if you used a third pary TC.
HTH