Multiple Extenders on Telephoto Lens

[Belmondo]

My 1.4X extender arrived in the the mail today, and I thought I'd give it a shakedown cruise this afternoon. I connected it to my 400 f/5.6L, and took a few pictures with that setup. Then, I got the bright idea of trying both my 1.4X and 2.0X extenders together. I figured the worst that would happen would be a bad, out-of-focus picture. Much to my surprise, the pictures actually turned out with that combination of len/extenders.

I'm guessing that that the two lenses together give 2.8X magnification. That's only a guess, and the EXIF data just shows 800 mm. Apparantly only the 2X was registering.

Anyway, here are the shots I took starting with the 50mm 1.4 just to establish perspective. The next picture is with the 400 5.6L by itself. The next picture was with the 1.4X Extender. Then, the 2X extender, and finally, both extenders (2.8X)

I just thought I'd share these with you. I hadn't realized I could use the extenders together.

http://www.bytephoto.com/photopost/data/500/353U50mm-med.jpg
http://www.bytephoto.com/photopost/data/500/353U400mm-med.jpg
http://www.bytephoto.com/photopost/data/500/353U560mm-med.jpg
http://www.bytephoto.com/photopost/data/500/353U800mm-med.jpg
http://www.bytephoto.com/photopost/data/500/353U1120_mm-med.jpg

[ChrisNardone]

Wow! I might have to get another tele-extender. You had to focus manually, right?

[Belmondo]

Yeah, in every case. It's amazing how touchy the focus is when you get the extender on the lens. If you breathe on the lens, it changes.

Tom

[CyberDyneSystems]

Thats a lot of magnification!

Beleive it or not,. there are some lens/camera combos where they will still autofocus with "stacked" tele-extenders. The 70-200mm f/2.8 does!

Soon I will have a 500mm f/4.5,.. with that I will still get autofocus @ 700mm (with 1.4X) but at 1000mm it will be manual. If I stack them I will have 1400mm @ f/12.6

[ChrisNardone]

CyberDyneSystems, I revisited your website. Very nice. There are a lot of people that would enjoy your bird photos at:
http://www.astromart.com/messages.asp?forum_id=9
By the way, what's the story with the Comorant?

[jim monroe]

belmondo,
Thanks, for a very instructive series of images.
It was especially interesting for me since I plan to purchese the 400mm/5.6L lens relatively soon.
With my usual obsessive mind I immediately imagine someone now trying 3 extenders on at once.
A couple of questions;
What was your sense of the sharpness of the photos as you increased the magnification? You can't always tell with images from the monitor.
Also my understanding, and I'm a newcomer, is that the f-stop increases significantly with the addition of the teleconverters. What were the aperture settings for the shots?

[CyberDyneSystems]

chrisnardone wrote:
CyberDyneSystems, I revisited your website. Very nice. There are a lot of people that would enjoy your bird photos at:
http://www.astromart.com/messages.asp?forum_id=9
By the way, what's the story with the Comorant?

Thanks for the link Chris,. I think you can expect me to drop in soon.... :)

[lightandlife]

Very impressive shots, Belmondo.

I wonder how many extenders can be stacked before the image is noticeably degraded. I presume you have not tried three. If 70-200mm were used with three 2x extenders, it could reach 200mm x 8 = 1600mm. With 10D, it would be more. Has anybody tried this?

[CyberDyneSystems]

Even with two 2X extenders you would be in rough shape. It might do in a pinch but you would allready be at f/12 or thereabouts... add a third and it's f/24 and I'm sure we are running out of the original lenses resolving power....

[kn_guy87]

Does it seem to you that the pix with 1.4 and the one with combined TCs are clearer than the one with 2.0 TC?

[lightandlife]

Years ago I bought a used Oxford English Dictionary from the UK, the one that needs a magnifying glass, but it was missing.

I had to buy two magnifying glasses. When I look up a word, I have to pile up these two magnifying glasses to make out any letters. At least the center was clear, if not at the boundary of the lenses.

[Belmondo]

jim monroe wrote:
belmondo,
Thanks, for a very instructive series of images.
It was especially interesting for me since I plan to purchese the 400mm/5.6L lens relatively soon.
With my usual obsessive mind I immediately imagine someone now trying 3 extenders on at once.
A couple of questions;
What was your sense of the sharpness of the photos as you increased the magnification? You can't always tell with images from the monitor.
Also my understanding, and I'm a newcomer, is that the f-stop increases significantly with the addition of the teleconverters. What were the aperture settings for the shots?

There's no question that sharpness falls off as magnification increases. It's hard to say what the effect is on the f-stop setting because as you increase magnification, you're actually taking a different picture with different ratios of light and dark. In the case of the pictures I shot, the f setting started at about f/13 with the bare 400mm lens, went to about f/11 with either of the extenders on by themselves, and ended up at back at f/13 with both extenders. (I think that's an anomoly caused by the larger area of the highly reflective subject relative to the overall picture)

The next time I conduct this experiment, I'll take more pains to find a neutral subject to photograph.

Tom