can you double stack teleconverters?

[andylawcc]

at least in theory, not by any practical means since you will be loosing all those f-stops

 

[996GT2]

You sure can, at least for most teleconverters.

You can even put like 5 or 6 of them together for a something like a 5000 or 10,000mm f/64 or f/128 lens if you REALLY REALLY wanted to.

 

[Fardringle]

As long as the teleconverters have matching threads on the front and back, you can stack as many of them as you want to, although you'll probably lose automatic focus and metering. Personally, I think the dramatic loss of image quality is the main reason why you wouldn't want to do this. Of course, if you really just want the maximum possible magnification without regard for image quality, then you could stack a bunch of them together as 966GT2 suggested.

 

[soydios]

Originally posted by: andylawcc
at least in theory, not by any practical means since you will be loosing all those f-stops

I've tried it. I used a TC-20E II (AF-S only TC) and a really old NT Rokunar 2x TC (basically replicates the pre-AI F-mount complete with aperture metering coupling). The image quality...uh...sucked, and the viewfinder was absurdly dark. 2x2=4x magnification, but that's also 4 stops of light loss. Nikon's AF-S TCs can't be stacked without hacking something off, I think.

 

[fuzzybabybunny]

I've stacked Kenko Teleplus Pros before. Oddly enough, a Sigma 1.4X stacked with a Kenko 1.4X actually had BETTER image quality than a single Kenko 2X....

 

[996GT2]

See this link for some test shots of a 12,800mm lens created by putting a Canon Extender 2x, a Sigma APO 2x, a Sigma APO 1.4x, a Tamron 2x, and a Tamron 1.4x teleconverters onto a Sigma 300-800mm "Sigmonster."

http://www.pbase.com/liquidstone/16x_tc