XSeries-forum

It is not so much the sharpness, it is the distortions that I have a problem with.

18-200mm is a big 'ask' for a single lens. It's approx 29 - 320mm in 35mm field of view equivalent (EF-S/APS-C sensor conversion crop factor = 1.6). For a single lens choice it's not bad, and the Canon is better than the Sigma. A lot of photographers would split the range to maybe a EF-S17-85 and a EF75-200 to reduce any distortions. You might also add a EF-S10-22mm for wide angle work. That being said, if you are using the Canon Pro Software it can remove those distortions on a number of lenses as the corrections are stored in the program now.

Hmm. Maybe I can chip into this thread and ask about a lens I want to by for my Canon 7D

I've just got the kit 15-85mm lens and so need a fairly long zoom (for sports and er, candid stuff!). I was looking at the 70-300mm L (f4-5.6) but then I had a play with 70-200 f2.8
BUT if I bought that I'd need a 2x extender, which seems to be about £500 although the converter is about half that price, does anyone know what the difference is between a 2x extender and a 2x converter (I presume they both take 2 f stops off the lens)? Has anyone got any experience of either of these lenses?

Thanks.

Convention say that a 2x Teleconverter will basically double your focal length to 140-600mm. An Extension device allows closer focus than is normally possible by shifting the lenses and therefore the normal minimal focal point away from the film plane. Annoyingly Canon call their Teleconverters 'Extenders' and their Extenders, Extension Tubes (which is conventionally correct)!!

Not all the Canon lenses are compatible with their 'Extenders' so you need to watch for that one. You may also lose some functions like Auto-Focus! Beware!!

My own experience of teleconverters is that not only do they stop down by at least two full stops, but they make the screen darker and focussing can be a really tricky art. Other than that they are fine. Oh, and you need a tripod unless you're shooting at high ISO numbers in bright light. I have a Sigma 100-500mm and a 2x teleconverter so giving 1000mm at full zoom. It's nice to use against distant targets, but I also have to use a tripod and cable release to prevent movement.

I haven't used extension tubes in years as I've not done any macro work. What I do remember is that it was very hot working under photofloods to get the lighting right for film use - no digital in them days!! These days you use a ring flash or similar.

Be very carefull with lens compatibility, I was reading the reviews a while back and was not overly impressed by the extenders, hence me not buying one. The general critisism was something like "they never told me it would not work on my type of lens" type thing.

Thanks for the advice X5Sport and pvr

It seems the converter is the mark 2 version and the extender is the mark 3 version - and twice the price!
http://www.camerapricebuster.co.uk/cat5.html

70-300 it (probably!) is then.