Camera Freezes with Extension Tube on it.

[Mary Anne]

Using my Canon 40D with the Tamron 90mm macro on it works ok though the focus does not seem the best lately.

Pop on the Kenko 36mm Ex Tube and the lens screams to find the focus on A/F so I put it on M/F then is freezes when I press the shutter button, and looking through the viewfinder I see a dark screen not black more a very dark grey like looking at a very noisy night time pic. I turn the camera off and I can still hear the motor going so I take out the battery and the CF card then I hear a click as though its fixed itself, I take off the ex tube and the problem disappears, there is no Error message.

Today I was taking a pic of a green spider having no problems then decided to put the Hoya +2 close up filter on it and the same thing happened it froze again as above and I did the same thing then removed the Hoya filter.. I have been using that close up filter for a couple of years and have had no problems with it before, though could never master the ex tubes that I got for Christmas having only used them about three times previously and thought I would give them a go recently and this is when it all started

Not game enough to put the macro lens with either the ex tube or the close up filter on my 5D so I was wondering if any of you great Folks on here have had this kind of problem with any of the accessories mentioned above.

Maybe it's time to buy a new macro lens as my little tamron macro could be worn out seeing its my oldest and most used lens, or perhaps its the 40D that's causing the problem, just wish I knew how to work out what is causing the problem hoping someone can help me here on how to check either of them out. Thank You.

[arthurking83]

Depending on the exact extension tube you got yourself, this could be perfectly normal.

Some extension tubes don't operate the aperture on the lens, but if the lens was trying to autofocus, then my guess is that this particular ext tube is of the more modern type that does AF and do automatic aperture stop down too. Some Kenkos do, and others don't.

By placing the extension tube between the lens and the camera, you're changing the focusing characteristics of the lens, in that it can now no longer focus at infinity. if the ext tube is operable in AF mode, and the lens is set to focus from close to infinity, you're confusing the camera(ie. the AF system), as it doesn't know that infinity is no longer achievable. I think this lens has mode whereby you can limit the focus range of the lens.

switch the camera to full manual mode and lens to manual focus mode.
the Tamron has an aperture ring(from memory) so turn it to the fastest setting (f/2.8) and see if this changes the darkened view through the viewfinder.
To operate the the lens normally on the camera, they're generally set and locked to the smallest aperture position(highest f/ number.. which I think is f/32 on this lens), and if the ext tube doesn't allow aperture coupling, then the lens fitted to the ext tube, fitted to the camera is subsequently fully stopped down.. resulting in a very dark viewfinder.. but lots of DOF

normally with these kinds of tools(ext tubes and close up lenses), full manual mode on the camera is the best choice.

[Mary Anne]

Hi Arthur Thank You so much and you are right looking back at the Exif data on the 10 or so shots I took this morning of the spider the first four were shot on Manual (like I usually do) and were too dark then getting up off the decking floor to go and get my speedlight I find I had forgot to recharge the batteries for it so I get down on the floor again and push the flash button on and I must have knocked it on to Av when I reached across to grab my glasses when they fell off the top of my head as I cannot see in the viewfinder when they are on my nose.

I did manage to get two pics in focus after all that with the flash on.

I will remember to always use MF in future and check that Mode Dial. Thanks again.