Stacked tc's with the 300/2.8 - samples

Just for a change last week I shot exclusively with stacked 1.4x and 2x Canon tc's with the 300/2.8 on the 7D (840mm with a FOV of 1344mm).
Because the Camera only sees the tc nearest to the lens when stacking Canon converters the EXIF reports 600/5.6 so AF is possible. I took over 300 shots all with AF. AF speed varied quite a lot from very reasonable to extremely slow - I was shooting with just the centre AF point but on a few occasions I had to resort to zone AF or all 19 points to obtain AF.

Although the results were nothing to write home about they were very usable IMO.

Nice IQ indeed, is that lens IS or original non-IS version?

Impressive!

Interesting that the camera sees only the closest TC to the camera. Do you notice any difference if you change the TC so that the 1.4x is the closer TC? It should report the lens as a 420mm f/4, but I'm not sure if that would make any difference in how the camera focuses, or in the overall results...?

ckhorne wrote in post #11717510
Impressive!

Interesting that the camera sees only the closest TC to the camera. Do you notice any difference if you change the TC so that the 1.4x is the closer TC? It should report the lens as a 420mm f/4, but I'm not sure if that would make any difference in how the camera focuses, or in the overall results...?

Chris, you can only stack one way: Camera > 1.4x > 2x > Lens. BTW it is the one closest to the lens (not Camera).

Good to know- thanks!

Owl_79 wrote in post #11717449
Nice IQ indeed, is that lens IS or original non-IS version?

The lens is the I.S. version. BTW I always keep I.S. switched on (mode 2) when shooting on a tripod.

Roy C wrote in post #11718017
The lens is the I.S. version. BTW I always keep I.S. switched on (mode 2) when shooting on a tripod.

Ok, I wish to see some 300 2.8L non-is samples w/teleconverters..

I carry both converters and on rare occasions I will stack them. Sometimes you get lucky. I have a few shots that are pretty good. Better to give it a try while you have the opportunity. Good light is essential. $12k for an 800 f/5.6 is an other option.

I have shot wildlife with the 400 2.8 IS and stacked TCs before and like you mentioned the results can be very usable. It is disappointing that the new 2x III is not stackable.

fotobean wrote in post #11722553
It is disappointing that the new 2x III is not stackable.

I agree, I have seen several reviews of the new 2x III with the 300/2.8 and it is looking really good but I would miss the ability to stack.

Great co-incidence that you posted this.

Earlier in the week I was just playing around & took some shots with the 300 2.8 IS but I used my Sigma TC's, the 1.4 followed by the 2.0.

Not great shots, just playing around. These are taken from the deck attached to my home, early evening on a quite hot day, hence the heat haze.

The first shot, the train is 2.98km away, the control tower in the next is 9.87km away. (I used TPE to provide the distances)

What kind of duck is number is the first shot

picken wrote in post #11723608
What kind of duck is number is the first shot

In order - Coot, Tufted Duck (female), Tufted Duck (male), Mallard (male), Coot.

Roy C wrote in post #11716879
Just for a change last week I shot exclusively with stacked 1.4x and 2x Canon tc's with the 300/2.8 on the 7D (840mm with a FOV of 1344mm).
Because the Camera only sees the tc nearest to the lens when stacking Canon converters the EXIF reports 600/5.6 so AF is possible. I took over 300 shots all with AF. AF speed varied quite a lot from very reasonable to extremely slow - I was shooting with just the centre AF point but on a few occasions I had to resort to zone AF or all 19 points to obtain AF.

...

I've found that when "cheating the AF" with stacked teleconverters, the AF sensors adjacent to the center AF point on the 7D seem to actually be more consistent at locking focus. This is opposite of the 5-series bodies where the center AF point is king.

I also found, at least with the 400/2.8 IS, that on the 7D, stacked converters took enough away from the IQ that it was almost a "wash" when comparing the stacked 1120 mm shots with the 800 mm shots using just the 2X. This was when viewed at 50% or 100% though - not something that might normally be noticable in the typical 8 X 10 inch print. I suspect that by the time you've stopped down an extra stop or so, the diffraction is fighting against the gain in focal length.

I'll have to do some experimenting in daylight - my experience with stacking has been primarily with moon photography.

Thes shots are quite good. What did you use for camera support, a gimbal head or a straight ballhead on tripod