Effects of Teleconverters

[tostitos]

Hello I am somewhat new to photography (only been at it for about a year), and I have a few questions (but I did searches first to try to find information before making this post)
I thought I would start out with where I am at this point.
I have a Rebel G II with Factory 35-80mm 4-5.6 lens (52-58mm step up ring so I can use 58mm filters)
A Tamron 19-35 3.5-4.5 Lens
A Sigma Super II Macro 70-300mm 4-5.6 Lens
Remote Shutter Release, Tripod, 58mm Red, Green, Circ Polar, and Sky filters.

Now to my Queery.
I have been searching for information all over the net to learn about Teleconverters, and I have found some mixed information. For the most part I have learned that since my camera doesnt have mirror lock I shouldnt use shutter speeds slower than 1/125 sec to prevent blurr when using my 70-300mm lens when cranked up to 300, even for macro, but I have taken some very very good macro pictures right at 1/125 sec if not slower with iso 100 neg film. So I am thinking that my camera might handle mirror movment a littler better than the average.
But this leads into my question. If I need to maintain a shutter speed of aprox 1/125 sec, can I do this with my 300mm + the new Kenko 3x Teleconverter?
Let me set up the conditions I would use it under. First I understand that my 300mm + 3x Teleconverter results in a min f-stop of 16 (approx) and a 900mm Lens. So with this setup on bright sunny days, would I be able to maintain a film speed of atleast 1/125 sec, with ISO 400 Film, at 900mm magnification to take pictures of small birds? And if so would I be able to blow those pictures up to a max size of 4x6 and produce a good quality picture? (not professional grade)
Also would there be enough light coming through the lens for me to be able to focus the camera, or even see what I am shooting at?

Also I read somewhere that you can take a 1.4x teleconverter and a 25mm extention tube and it will result in a 2x teleconverter costing you only 1.5 f-stops instead of 2, so in that case, would I be able to take a 2x teleconverter and 50mm (or more) worth of extention tube to make a 3x teleconverter that wouldnt take as many fstops? (I thought that Extention tubes were only for macro photography)

Any Help or Information would be much appriciated.

thanks

 

[Jeff Canes]

A few of us here have some experience of shooting sports with long lens.
I am not very good with the technical questions. That setup may work, for sports with good light but birds are a lot smaller the athletes. My experience and intuition tell me that you will not be able to get good sharp details of small birds. I think that you will need better lenses.

 

[drlynn]

When you get out to 900mm, you are probably gonna have problems with blur even at 1/125 shutterspeed unless you're using a tripod. I don't have a lot of experience over 300mm, but I think you're gonna have trouble getting acceptable shutterspeed at f/16, even on sunny days.

Also, keep in mind that AF doesn't work for most of the less expensive Canon lenses with a teleconverter attached, so you're gonna have to manually focus, which isn't gonna be easy stopped down to f/16 with no focusing aids.

You can check the speed part without the teleconverter. Just put the lens on, go out in the sun, set it on APerture priority, set teh Aperture at f/16 and see what shutterspeed the meter sets.

If the G II has DOF preview, press that button with the aperture set at f/16 and see if you can see well enough to focus.

 

[tostitos]

Thanks for the help this far
here were a couple sites that I was looking over for information

http://www.camerahacker.com/stacking_teleconverters/
http://www.profotos.com/education/promag/articles/april2002/bird_photography/index.shtml

I used these links because it deals with the magnification I am talking about even though they are talking about stacking to get 3x I was thinking about a straight 3x.

As to the lens, would it be an accurate test to see how my lens would act at 900mm, to zoom my camera all the way out to 300mm and set the f-stop to 16?

I havnt tried that test with mine (been raining over here for the last week) but I have used my friends Sigman 70-300 Super Macro (old model) and I commonly shot photos at 22 up to 32(?) I think with speeds at 1/250 a second or so.
Would I be better served with a 2x teleconverter, and if so would it work for small birds?

If I did deside to get a 3x teleconverter, what kind of things would I be able to take pictures of?

Thanks