I have a 400L f/5.6 and got tempted into wondering if a combo with this extreme teleconverter would work at all. For moon shots, distant landscapes etc. Anybody with any experience...?
I have no experience with this combo, but I highly doubt that you will be happy with the results. You end up at f/16, so the viewfinder will be very dim, and focusing extremely difficult. Then you want to stop down at least one stop to recover some sharpness, which now leaves us at f/22. At that f-stop you run into diffraction problems, and the shutter speed will be so slow that you'll need excellent long-lens-technique.
In short: I would try a 2x TC first. I'm sure that it's going to be easier to use and give you better results than the 3x. And if the 2x works, you can stack it with your 1.4x TC, to give you an effective 2.8x TC, and see whether or not you like it.
I used a similar setup with my old Canon Ftb, a vivitar 400mm lens and a Kenko 3X. I was shooting a lion kill from a boma up on a hill overlooking a waterhole in Kenya. The results were grainy, as can be expected, but the shots were all great.
I've heard the 3x TCs are pretty poor quality. I've used the 2x TC II and 1.4x TC II from canon, stacked on my 500 f/4L IS and obtained very good results, but even on that combo you are f/11 wide open and thus need to stop down to f/16 for best results. Rainer is correct, I wouldn't want to try the 400L with this setup and have to stop down to f/22 especially on a crop body. It may work ok on a 5D but would still need a lot of sharpening and may still look ordinary.
Pixel Perfect wrote:
... even on that combo you are f/11 wide open and thus need to stop down to f/16 for best results.
I have to admit I don't use teleconverters all that much, but why would I need to stop down? Isn't a teleconverter already looking through the central (i.e. theoretically sharpest) part of the lens?
duncanidaho332 wrote:
I have to admit I don't use teleconverters all that much, but why would I need to stop down? Isn't a teleconverter already looking through the central (i.e. theoretically sharpest) part of the lens?
Yes, it's looking through the central part of the lens, but for some reason, stopping down one stop makes quite a difference in image quality, especially with the 2x TC. This has been mentioned by others, and I have seen it in my own tests, too.
Rainer wrote:
... for some reason, stopping down one stop makes quite a difference in image quality, especially with the 2x TC. This has been mentioned by others, and I have seen it in my own tests, too.
Interesting. Whenever I've tried the 2x, I thought the results were horrible. Maybe this is what I was doing wrong.
duncanidaho332 wrote:
Interesting. Whenever I've tried the 2x, I thought the results were horrible. Maybe this is what I was doing wrong.
Depends on which lenses. The TCs were designed with the superteles in mind and were optimised for those lenses and as such the results are very good on them (if you use good technique). However, the extra glass does cause a loss in contrast and sharpness and stopping down will help ameliorate this considerably. The MTF curves reveal this. I use the 300 f/2.8L IS and 500 f/4L IS and when used with a 2x TC both improve stopped down, although the 300 combo does well wide open but even 1/3 stop helps a lot.
