[J dear]

Hi,
Iuse a 350D with the Tamron 200 -500 zoom. In comparison to digiscoping a Nikon 450 on Opticron 80mm scope, the images are much clearer, and with Photoshop tweaking , about the same size. Would the addition of a Sigma
x1.4 teleconvertor be worth the effort? I acknowledge that I would probably lose AF, but are they compatible and worth the expense? I'm sure that someone out there has tried this before, so apologies if I am repeating a thread.
Thanks
john

[postcardcv]

I've not used this lens but I woudl think that you would be right about loosing AF (even with the pins on the tc taped). So it will be a matter of how you get on with MF, personally I'm not great at manually focusing so would prefer to shot at a shorter focal length and retain AF. If you do decide to go for a 1.4x tc then consider the Kenko 300 pro, it is as good optically but costs a lot less (~£65 new on ebay).

[gmax]

Originally Posted by J dear

Hi,
Iuse a 350D with the Tamron 200 -500 zoom. In comparison to digiscoping a Nikon 450 on Opticron 80mm scope, the images are much clearer, and with Photoshop tweaking , about the same size. Would the addition of a Sigma
x1.4 teleconvertor be worth the effort? I acknowledge that I would probably lose AF, but are they compatible and worth the expense? I'm sure that someone out there has tried this before, so apologies if I am repeating a thread.
Thanks
john

Hello John,
some sound advice from Pete here, but I'll add just one thing; I own the same kit and I would NOT add a TC to this lens (Canon, Sigma or Kenko doesn't matter in my opinion): I've tried with a Canon Extender 1.4X and there's a very slow focus speed and above all too much IQ loss .. so I'd forget about a TC
Cheers,
Max

[rockwright]

There is a way of increasing magnification on your lens with NO degredation in image quality, and that is by using extension tubes. Art Morris devotes an entire chapter to this in the book The Art of Bird Photography but I never see anyone bringing it up in a forum. Another advantage is that it allows closer focus. I am certainly no expert, but in my opinion the best pictures I've taken were ones where I managed to get close to the bird.
The tubes increase magnification of the image on the films sensor by increasing the image distance from the sensor - like moving a slide projector back to increase the size of the slide on the screen. There is a loss of light using this setup but on my sigma 170-500 lens the autofocus still works.
I am trying to post 2 images - a bluebird shot with a 12 + 20 + 36 mm tube and a tree swallow with the same setup but also with a 1.4x extender. The swallow is a little soft IMO and I had to autofocus. I have, however, gotten some passable images with the extender. If I'm shooting songbirds I usually have a 20 mm tube on.

[rezMole]

I have the Tamron and a Kenco Pro 300 1.4x. I don't, however use the converter on the Tamron, unless it is for "Close-up" shots. Trying to shoot distant birds with this combination just makes the images end up being too soft.

I just crop more off the image to get "closer", when printing.