Stacking tele extenders?

After reading another post here, I got to wondering if anyone uses stacked tele extenders? I use a 2x extender on my 70-200 f2.8 IS lens for wildlife, and often come up short. I wondered if another extender might give me more reach, or is there so much distortion and abberation that it isnt worth it? Wishing I could afford a 400 f2.8, but owell. (lets see, 400mm x2 with extender, x1.6 with crop = 1280mm. That should do it)

Two 2x teleconverters is a loss of 4 stops of light - you'll finish up with an 800mm f/11 lens that will be difficult to focus (and certainly won't autofocus), a very dim viewfinder and probably significant distortions. The IS isn't likely to be much use with 4x of teleconverters either.

If you need the big stuff for a bit, why not hire it? A 600mm f/4 with a 1.4x is a little bit longer, will autofocus on any body (it's an 840mm f/5.6 combination), the IS is likely to work just fine - and you will need a sturdy tripod if you value your back! (The other alternative is a 400mm f/2.8 with a 2x - but if you really need the length, I suspect the 600mm lens is the right option).

David

Thanks for the response. The problem is I live in the hills, carry the camera everywhere. Rental is out, so next is the weight and cost issues. Weight is not the problem, I am strong and healthy, and the wildlife is in my wifes flower beds here at the house.(Deer love roses like candy to a baby) Cost however, I cannot justify the cost of a 600mm lens for a hobby. Hell I dont even pay that much for automobiles. Owell Maybe I will hit the lottery one day Have a good one.

I wouldn't suggest stacking many TC for wildlife. They move too much and autofocus will be really slow and you will need a lot of light. I would suggest to use 1 tc & just crop more until you can afford a longer lens. When you go to print, even if you crop half just the center 4mp image (I'm assuming you have a 8mp or 10mp canon) you can still print excellent 4x6 images and decent 8x10

I have done tests on double stacking the 1.4X and 2X II for academic interest with the 200/2.8 and 300/4, of course the results are a lot less sharp than they are with less or no TCs but still better than upressing. http://www.zen20934.ze​n.co.uk …nsTests/tc_comp​/index.htm

I have not tried this in anger so to speak, probably really not practical with anything other than f2.8, the 300/2.8 might fair better, I suspect zooms a lot less well.

I'm not sure about the dark viewfinder part. I think it *may* have been overexagerrated. Just turn the aperture to f8.0 and hit the DoF preview button...I think that's the result of 2 X 2x extenders

EOS Man wrote in post #3302640
I'm not sure about the dark viewfinder part. I think it *may* have been overexagerrated. Just turn the aperture to f8.0 and hit the DoF preview button...I think that's the result of 2 X 2x extenders

With the 300/4 1.4X and 2X stacked that is f11, I had no trouble manual focusing although that was with a stationary high contrast test target, with wildlife in the field another matter I would think.

Not heard of anyone double stacking two 2X.

I have a 100-400 and found that even with the 1.6 crop factor that I just didn't have enough reach so Kenko 1.5 to the rescue, and it does auto focus even in low light conditions. IQ was respectable. But being greedy and wanting a little more reach I added a Kenko 2X with the 1.5 and as stated it loses AF and a "few" stops of light, and Image quality degrades slightly but IMO not as bad as cropping 200 percent to get the shot you want. If your on a budget it'll do in a pinch. So 20D X 1.5 X 2.0 X 400 = 1920 mm.
Here are a couple shots taken at over 100 yards away rested against a running truck window. Sharpened and color corrected from raw. Shots under 100 feet are very nice!

HOSTED PHOTO
please log in to view hosted photos in full size.

HOSTED PHOTO
please log in to view hosted photos in full size.

I use stacked teleconverters a lot with my 500mm f 4L IS lens. Stacked teleconverters do not perform well with zoom lenses, however. You really can only get the best results when using very highly corrected telephoto lenses. I have a 300mm f 4L non-IS lens that I have stacked teleconverters on but it does not perform as well as the 500mm lens. Here's links to 3 articles I found on the Internet regarding stacked teleconverters...

http://www.tomwebsterp​hoto.com …converters/stac​kedtcs.htm

http://www.tomwebsterp​hoto.com …kedTcsII/stacke​dtcsII.htm

http://www.tomwebsterp​hoto.com …dTcsIII/stacked​tcsIII.htm

Pretty interesting stuff. These articles are what got me to try it in the first place.

I agree with Billy- if you've got decent light you aren't going to beat the 100-400 for versatility. This glass combined with a Kenko 1.4x or Soligor 1.7x gives some great reach with only an extra 1 or 1.3 stop loss. I think you'll find better IQ with this glass than the 300 f/4 with a TC or the 100-400 with a 1.4 v. the 300f/4 with a 2x TC.

I have tried to stack 2x and 1.4x Canon Extenders with interesting results. It should have been a three stop hit on my 2.8 lens. Camera only saw the 2 stop hit, let me shoot in f/5.6, autofocus worked but hunted at times. EXIF data showed an actual f/8 exposure though.

The thread is here:
https://photography-on-the.net/forum/showthre​ad.php?t=317553

milleker wrote in post #3303334
I have tried to stack 2x and 1.4x Canon Extenders with interesting results. It should have been a three stop hit on my 2.8 lens. Camera only saw the 2 stop hit, let me shoot in f/5.6, autofocus worked but hunted at times. EXIF data showed an actual f/8 exposure though.

The thread is here:
https://photography-on-the.net/forum/showthre​ad.php?t=317553

Yes I found the same thing on the two lenses I tried this on. With the the 200/2.8 it should not have AFed at f8 but the camera thought it was f5.6 and so tried to AF. On AI Servo you could see the camera zero in on the correct focus, I guess one shot would result in a spread of focus accuracy.

Here's two more for you TomHuckWa!
About 10 feet away, no PP just saved for web and at some great risk to life and limb from its concerned, divebomber parents. Full frame and 100% crop. Just about what you'll find in your "Flower Bed" Studio!
Oh yea, forgot to mention that this shot was hand held in the shade. You can almost see me
in its eye. Purty cool!

HOSTED PHOTO
please log in to view hosted photos in full size.

HOSTED PHOTO
please log in to view hosted photos in full size.

Hey thanks everyone for the responses. I think I will order another extender, as I can live with those results and even working for the picture is better than not getting it at all. I am not a pro, so people expect some irregularities in my photos. Thanks again Tom

milleker wrote in post #3303334
I have tried to stack 2x and 1.4x Canon Extenders with interesting results. It should have been a three stop hit on my 2.8 lens. Camera only saw the 2 stop hit, let me shoot in f/5.6, autofocus worked but hunted at times. EXIF data showed an actual f/8 exposure though.

The thread is here:
https://photography-on-the.net/forum/showthre​ad.php?t=317553

FYI, when you have multiple teleconverters attached to Canon cameras, the only teleconverter reported by the camera is the one attached to the lens. The second teleconverter against the camera body is not recognized by the Canon camera to affect autofocus. This is why I will stack 2, 1.4x teleconverters on my 500mm f 4 lens when shooting with my 30D. The camera only recognizes the first 1.4x tc attached to the lens, doesn't see the second teleconverter, and allows my 30D to autofocus with both teleconverters. Cool!