Originally posted by First Poster I wasn't going to do this but, just out of interest, would this work?
Would you lose much IQ?
Yes, it may work - sometimes. But as already said:
Originally posted by Mikesul Double teleconverters can help in only a limited number of circumstances.
Just to show that it can be done, here's a special example:
A 350mm catadioptric lens plus two 2X teleconverters stacked.
That makes a 1400mm system that......
....may produce this under good atsmospheric conditions.
(non-cropped, downsized image)
100% non-resized crop of the above
(click on images to see larger versions)
Here cropping of a 350mm image would produce much less detail, because in THIS situation, the sensor resolution (: the spatial resolution) is the limiting factor. But it's definitely not a setup I would recommend for birding.........