[Phoenix_splx]

Hello (New by the way)

I have a 20D, Canon 75/300mm USM & Sigma Macro II APO 70/300 and I want to Extent the zoom to 600mm if poss on one of these lens's. What do I need to buy for this ?

Thanks in advanced

[Steep]

Something like this

http://www.7dayshop.com/catalog/prod...ducts_id=98420

or its big brother

http://www.7dayshop.com/catalog/prod...ducts_id=98421

I expect

[Steep]

Or this

http://www.7dayshop.com/catalog/prod...ducts_id=99499

[Phoenix_splx]

Yeah I was looking at the Canon telephoto converters but it doesnt list my 75/300 USM as a compatable lens ?

[Steep]

Of course it is, it's an EF lens isn't it?

[silkstone]

The 1.4x TCs are compatible with Canon EF lenses that have a maximum aperture of f/5.6, provided they are 7-contact lenses which most of them are - apart from some L-series which have 10 contacts.

The 2x TCs are compatible with EF lenses f/4 and faster, again provided they have 7 contacts.

With 10-contact lenses, the apertures are f/4 and f/2.8 for the 1.4x and 2x TCs, although it is possible to fool them by taping over three of the contacts!

This means that you should be able to use a 1.4x TC with your 75-300 f/5.6, but not a 2x if you want to retain AF. If you're willing to focus manually it doesn't matter, but manual focus isn't easy with a standard viewfinder and a fairly dark image. Remember that a 1.4x TC will reduce the maximum aperture by 1 stop, and a 2x TC by 2 stops.

The Canon TCs are very expensive and really no better than the Kenko Pro300. If you do an eBay search you'll find at least two HK companies selling the Kenko Pro300 for around £85 + postage. Make sure you get the Pro300 version though - they do a cheaper one which isn't as good. (BTW, I believe that Steve has one of these.)

Hope that helps!

[Phoenix_splx]

Yea it does from both of you. I know this is going to sound really basic but reason I thought about the incompatable was Jessops listing a range of EF lens's (this one not been one of)

I need 2x really so I guess I wil look at the Kenko kit.

[Steve]

Originally Posted by silkstone

(BTW, I believe that Steve has one of these.)

Hope that helps!

I do indeed have a Kenko Pro300 1.4x teleconvertor and I am totally happy with it.

Silkstone's answer above pretty much covers all the details spot on though so there isn't much to add. I would also suggest having a look at the Tamron convertor as well but I have been informed that it also uses exactly the same glass as the Kenko but is generally slightly dearer. Results wise there is nothing much between the ones listed here but make sure you do go for the "pro" versions though as they are worlds apart from the normal range and not that much more cost wise.