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Those of you who have both, I am trying to make a final decision
and this is one of the things that I am very curious about.
I know that there could be an autofocus issue with an untaped
2x Tele and the 7D. I just wonder how bad it is in real life usage.
I would primarily be using it with the 500 F4.
Any advice or info would be helpful.
thanks
Garry
I would stick with a 1.4x TC. The image quality is noticeably better and you don't have to worry about AF.
Hi Garry Stay away form taping pins, if you ever need just go manual focus. Fully agree with Axel !!
Hi Garry,
I don't have a 2x but have (2) 1.4x's and a 600mm f/4. One of my TC's does not have all the pins and does not report to the 7D. The 7D will not accurately autofocus with both TCs, although sometimes it lucks out and gets it right. I did find that autofocus in Live View on the 7D does accurately autofocus albeit slower with 2, 1.4x TCs.
Of course, the Mark III will work with 1.4x's stacked with the 600mm f/4 lens.
BTW, the Mark III with two 1.4x TC's is pretty close in resolution/quality to the 7D with one 1.4 TC when cropped accordingly. You do lose light however with two TC's vs one.
If you are trying to decide whether to buy a new 7D or a used M3 for bird/wildlife photography, my vote is for the 7D.
Alan
Thanks guys I really appreciate the information. Its helpful to have information
from people who have used the equipment in pretty much the way you
anticipate using it yourself.
GG
I experimented with 7D, 500mm f/4 and taped 2x and it would not autofocus. As Alan mentions the Live View autofocus does work (slowly) and gives very precise focus. It is really only practical where the subject remains stationary for a while.
The others have nailed it, I had 2 2X TCs and sold them both and stick to my trusty 1.4X TCs
If I had to choose between 7D and Mark III, I would go for the Mark III because of the better noise performance. YMMV
Axel,
I agree and disagree with your statement regarding lower noise performance. This is true if you can walk up to your subject and take the picture otherwise noise levels are similar.
When photographing from a set distance and cropping images identically, noise levels are very similar and the 7D has better resolution. The Mark III's 1.3x sensor requires heavier cropping than the 7D's 1.6x sensor to frame the bird identically.
Your statement is correct if you can walk up to the bird and photograph it. The Mark III has lower noise at similar ISOs. Unfortunately it is not very often that I have that luxury.
I have drafted a paper about this (real world examples) in case anyone is interested. This is why I wrote about creating a standardized test for focal-length-limited situations in the field:
http://iwishicouldfly.com/iwishicoul...Mark%20III.pdf
Cheers,
Alan
how can you stack 2 1,4x TC? One Canon and one other brand?
Yes, it depends upon who makes the TCs. Tamron and Kenko make TCs that can be stacked. I believe the problem with the Canon and a few others has to do with the protrusion of the back lens element.
Alan
Alan,Quote:
Originally Posted by Alan Stankevitz
Nice writeup and I agree with your conclusions. A couple of things to note. With a 1D series camera, you can go 2x TC and still have good autofocus, which is closer to equalizing the images from the 7D versus 1dIII. Another situation where they will be closer is when you stop down more: the 7D's resolution will be more limited by diffraction. And finally, as ISO goes up higher, and ligh levels drop (e.g. night photography), the read noise will become a larger factor in the 7D before that of the 1DIII.
My apparent image quality metric (AIQ) in figure 9 at:
http://www.clarkvision.com/articles/...mance.summary/
shows the 7D delivers slightly higher image quality than the 1DIII. Note the predict for the 1D4 is much higher than either. I will have real data for the 1D4 soon.
Roger
Thanks for the feedback Roger.
Yesterday, I did stack (2) 1.4x TC's on the Mark III and compared that to the 7D with (1) 1.4x and the resolving power was almost the same. It is amazing that an "old 10 megapixel" camera can compete with camera's with higher megapixel counts and greater sensor density cameras. I wish Canon would stop upping the megapixels on their cameras and focus their energy on image quality.
Alan
Anal what kind of 1.4 are you stacking? I'm not completely satisfied about the TC 2xII canon so I would like to try a double 1.4 configuration to check if could be a better choose than a single 2x.Quote:
Originally Posted by Alan Stankevitz
P.s. I'm using a 7D with 300 2.8 IS atm.
