EOS R6 Mark II Trouble Focusing using both 2x and 1.4x extenders with extension tube EF12

[enriquehoja]

Hello all,

I am having trouble focusing with my R6mII and adapted EF 200 F/2 lens using the extension tube between both extenders. I cannot focus to infinity and have read that this should work with most lenses, including this one.

[shadowsports]

Greetings,

This does not surprise me.  I know there are sites that tell you how to do it, but Canon says don't do it.

What I might recommend is buying a longer lens.

[enriquehoja]

Hi Rick,

Thanks for replying. Where did you get that from? The instructions for the lens?
I read this https://shuttermuse.com/how-to-stack-canon-extenders-teleconverters/

I have also read of people doing this so I am surprised that this telephoto prime does not focus in the distance, though for macro it indeed may work

[deebatman316]

When you use extension tubes you loose the ability to focus to infinity. The lens now sits further away from the image sensor where AF takes place on a mirrorless camera. OR on a DSLR the lens sits further away from the AF sensor.

[jrhoffman75]

The first sentence of your linked article states loss of infinity focus. 

[enriquehoja]

Thanks for your reply. Yes, you are correct. What surprised me is that I cannot focus on things closer than or beyond 3-4 meters. At about 4 meters, I reach focus, which is displayed as 10m on the dial. I intended to shoot the moon, and things that might not be quite at infinity, but this lens focuses way too close for this, or really even wildlife.

[FloridaDrafter]

Have you tried the built-in digital 2X and 4X tele-converter feature in the R6 mark II? I tried it with an RF 100-500mm L for some moon shots and it was fair, but not as sharp as I would like. It's not for everyone, but with some sharpening it does work. The downside is it's JPeG only.

Newton

[amfoto1]

It is possible to stack Canon teleconverters, by fitting a 12mm extension tube between them. The extension tube is needed because all the Canon teleconverters have a protruding front element that will physically interfere with stacking them with another teleconverter... and in fact limits the lenses they can used upon. The space created by the extension tube prevents the front element of the one teleconverter from interfering with the rear element of the other. Whether the lens will be able to focus to infinity or not with this extension really depends upon the lens.

Both the images below were shot using Canon EF 500mm f/4 IS USM lens (1st version) with EF 1.4X II and 2X II extenders stacked behind it. Focus was done manually.

This first image was a test to see how if the lens and extenders would work. The black tail mule deer was probably about 1/4 mile away. The image isn't great... probably due to camera shake. Even on a sturdy tripod and with IS working, 1400mm is a lot of focal length to try to keep steady. PLUS, this was on an APS-C camera, so the effective focal length was more like 2240mm!

Above image was not cropped and took a lot of work in Photoshop to make it at all presentable. Even then, I wouldn't ever display it very large... Probably no more than, say, a 5x7" print. It just doesn't have sufficient quality for anything larger.

This image is a composite. The moon was shot using the same 500mm lens with 2X and 1.4X on APS-C digital (both of these images were done with EOS 10D... all of 6MP!). The wolf was photographed a couple years earlier using a film camera (Elan 7, if I recall correctly), an EF 28-135mm lens and 550EX flash. She was a beautiful "ambassador" wolf who visited schools in southern Oregon or could be visited at the sanctuary where she lived.

Dakota had been found injured beside a rural road. She'd been shot. She was nursed back to health, walked with a bit of a limp, but always was a really sweet girl... not a mean bone in her body. Unfortunately she died about a year after this photo was taken at around 6 or 7 years of age. The bullet from years before had just done too much damage.

I always liked this photo of Dakota, but wasn't happy with the plain black background. So one clear night I decided to try some moon shots. This time I had better luck keeping everything steady on the tripod. In fact I ended up softening the details in the moon a bit, while compositing the two images in Photoshop.

Once again, both the deer and the moon had to be focused manually. The AF systems of the cameras couldn't handle the effective f/11 aperture of the f/4 lens + 2X + 1.4X. (I don't recall which extender I put next to the camera and which next to the lens... or if would make any difference.) However, the EF 200mm f/2 is two stops faster AND the R6 Mark II is able to autofocus at least two or three stops lower light conditions than any of the DSLRs.

So, it is possible. But it may mean manual focusing and may have a lot to do with the specific lens used with the stacked teleconverters. In this case, the 500mm has enough leeway "beyond" infinity that it's no problem using the 12mm extension tube between the teleconverters. That may not be the case with a 200mm lens.  

EDIT: FWIW, both the shots below of small birds (Anna's hummingbird and bush **bleep**) on their nests required an extension tube on the 500mm lens to make it capable of focusing a little bit closer. I'm pretty sure I used a 36mm tube in both cases (a Kenko, Canon's longest is 25mm) in order to make much difference in the lens' minimum focus distance. If I recall correctly, that particular lens' MFD is about 15 or 16 feet. No teleconverters for these images... just a fairly large amount of extension to be able to focus a little bit closer.

Now THAT'S HILARIOUS! I got "bleeped" over the name of a bird! Hah! 😎

Spoiler alert, the name of the bird is only three letters, starts and ends with "T" and has an "I" in between. Didn't even occur to me that it might get bleeped! 😁

***********

Alan Myers
San Jose, Calif., USA
"Walk softly and carry a big lens."
GEAR: 5DII, 7DII (x2), 7D(x2), EOS M5, some other cameras, various lenses & accessories
FLICKR

[enriquehoja]

Beautiful images! I would love to try it on the EF 500 but don't have one. I was hoping to reach at least 500 with this combination, a sandwich with the 12mm tube in between as you did with MF at least, but I guess it's not possible to do much with distant subjects if going the 200 or a 70-200 route.