Teleconverter and autofocus

[nicolas_delorenzi1]

Hello, my name is Nicolas and I am biology student.

I am starting to take pictures of nature ( just for my pleasure ),

especially birds, but I am limited by my machine that is a

Canon Rebel G, with a Zoom Canon 75-300 F 4-5.6 Usm.

I have bought a teleconverter Tamrom 2X C-AF, but I lose

the autofocus. Is there some form of maintaining it?

And, What negative film do you recommend me?

Thank you for your advice.

I have already learned a lot reading your opinions.

Pd: I do not have money for better lens.

[kevin_han]

When you put a 2x converter on a lens with f/5.6 max, the result is an effective aperture of only f/11. Usually camera's don't AF below f/5.6. What good is a lens at f/11 anyway. Too dark, no AF and no way to confirm focus. If you still decide to keep the converter to use it, go get something like a 300mm f/2.8. That way, you'll get 600mm and f/5.6. Just nice. Even better, just get a 600mm f/4 straight. No cash? Not to worry. You already have 300mm. Damn. Mine got smashed.

[mikemilton]

Nicholas,

 

Canons (other than the EOS3) won't autofocus reliably at the maximum apeture that results. You alos won't find it easy to manually focus (and you would not, even with an old split-focus screen as they tend to 'go black' as well). So... you have a couple of choices

 

Spend money as above - not a choice, you say. Not something I'd recommend until you are sure it's worthwhile anyway

 

Shoot at 300 and enlarge a portion of the negative - Likely your best option and likely to give as good results as you will get using an aftermarket 2x on the lens you mention. If you are shooting birds use a low speed film in bright light with a tripod and focus on getting closer to the subjetc (or drawing it to you)

 

Good Luck, have fun and lets see some of the results