Canon extender 2x mk ll on Canon 6D produces black images - SOLVED

[Starlight90]

Hello everyone,

I have a Canon 6D camera and 2 2x mk ll EF extenders (canon official), I have read that you can stack these extenders and get a bigger and better view of an object.

The Lens I'm working with is a  canon EF 100-400mm f/4.5-5.6 L IS USM Lens with the 2 extenders, however my live view doesn't with them both attached to my camera and lens, but I can see through the view finder, after I've taken some photos of the moon just to test and observe, I go back to check to see how they came out, it's all black, like nothing was taken, just a black void.

Can anyone advise?

Thanks 

[Waddizzle]

I also have a bad back, so I can relate to those related issues. 

Stacking extenders is inadvisable, IMHO.  The expected gains do not support the means.  Download the manual and do a search for “lens groups” for a detailed explanation of how extenders and specific lenses work with your camera.

I understand that you are manual focusing, but your image quality will take a major hit.  There is no substitute for having actual focal length in your lens.

[Starlight90]

I have a printed manual for my camera 

[ebiggs1]

"Stacking extenders is inadvisable, IMHO."

Mine too, in fact any 2x tel-con is not a good idea, IMHO. It is a fool's errand to spend your limited funds this way. Don't do it. Have you looked into a t-mount and a t-mount to Canon for your telescope? Way less than a single 2x te-con even a used one.

[Starlight90]

I don't use tel-con, I use the official canon 2x extenders. These are stackable. I won't use cheap knock offs unless they are recommended. 

The tel-cons aren't compatible with L series lens

[ebiggs1]

A tel-con and an extender is the same animal, my friend. Just different nomenclature and still a very bad idea.

[Waddizzle]

Another issue with using 2x extenders is that you may get “ERROE 01” messages with certain lenses, Exp specially if you begin to stack them.

Again, there is no substitute for have a lens with the actual focal length you want or need.  

Teleconverters are not cheap.  Only certain models will work with certain combos of camera and lens.  That is why I suggested that you download the manual and search for “lens groups”.

[Starlight90]

I got no error code message. I use the official canon L series extenders

[Waddizzle]

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@Starlight90 wrote:

Hello everyone,

I have a Canon 6D camera and 2 2x mk ll EF extenders, I have read that you can stack these extenders and get a bigger and better view of an object.

The Lens I'm working with is a  canon EF 100-400mm f/4.5-5.6 L IS USM Lens with the 2 extenders, however my live view doesn't with them both attached to my camera and lens, but I can see through the view finder, after I've taken some photos of the moon just to test and observe, I go back to check to see how they came out, it's all black, like nothing was taken, just a black void.

Can anyone advise?

Thanks 

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If your screen is black, then you need to enable ExpSIM in the camera.

[Tronhard]

I suspect that the reason it's not working for viewing through the live view compared to the viewfinder is that one sees the image via the viewfinder with the aperture wide open, which is not how the image will be captured.  Live view reads the image off the sensor with the aperture closed down.

My research indicates that the minimum f/stop with the 100-400L on the 6D is f/8.  Each 2x extender added will cost 2 stops.  So, with 2, 2x extenders that gives f/8 - f/11  - f/16 - f/22 - f/32!  When looking at an essentially black universe at f/32 it's going to be black! So, to try to get a decent exposure one would have to crank up both the ISO and extend the shutter speed to a period where I would predict there is almost certain to be movement of the earth, resulting in star trails.  That isn't even addressing the significant impact on the image from diffraction.

I am not an astro photographer, so if someone here is, can they confirm or correct this logic please?

[Waddizzle]

“ Live view reads the image off the sensor with the aperture closed down. “

Maybe.  If the exposure is set with the Aperture wide open, then Live View with ExpSIM enabled should see the same exposure as the OVF.

The problem could be that ExpSIM is running out of gas beyond a 30 second exposure.  I noticed that he mentioned a tracking mount.  The issue could be as simple as the exposure times are too long for Live View in Bulb Mode.