Can't focus with extension rings on Canon

[Aquarium Dreams]

I have some Kenko extension rings and when I attach them to my camera (400D) and lens, the camera won't focus. I've tried manual and auto focus and various combinations of rings with different lenses, all to no avail. I'm thinking about returning them, but others seem to have great results with these. Am I doing something wrong?

 

[TomHuck-wa]

I have Kenko rings, and a 20D, they work fine. You will have a very narrow fov, mine is out there a ways with the 200 lens. Put the rings and lens on, find a contrasting spot, (I used a doorknob on a white door) look thru the viewfinder and move back and forth from 1 foot to 6 feet or so very slowly, depress the shutter button half way every foot or so, till you see if it starts to bring the subject into focus. Hope this works for you.

 

[Big Mike]

I agree with that. Your depth of field will be extremely narrow...and I believe that extension tubes also prevent your lens for focusing at infinity. With the tube on, start with the lens very close to something and slowly move back until you find where your working distance will be.

 

[Aquarium Dreams]

Thanks, and WOW, you two weren't kinding about the narrow focus. The wider the lens, the closer I have to be to focus with an extension ring. I added the 12mm ring to my 28mm lens on the 400d and there might have been space to slide a couple playing cards between the front element and the surface in focus. Every combination of lens and rings focused really close. 300mm with all three rings focused at about four feet and my cat's eye filled a quarter of the frame. Is this normal? I suppose I was expecting more of a telephoto effect versus the macro effect I'm getting. These could be fun, but they're not exactly what I thought they would be.

 

[250Gimp]

Extension Tubes are for macro type work. They allow you to focus with the lense closer to the subject than without.

If you were wanting more zoom than you would need a tele-converter to magnify your zoom lense.

Cheers

 

[Big Mike]

Extension Tubes are for macro type work

:thumbup:

 

[Digital Matt]

Extension tubes are for macro photography. They take away your infinity focus and allow you to focus closer. Using all 3 kenko tubes (65mm) on a 50mm, gives you better than 1:1 reproduction.

 

[Aquarium Dreams]

:lmao: Well, now I wish I had done more research before buying. In my defense, I read an article that suggested buying these with my 24mm TS lens to "get more miles out the lens," or something to that effect, and I assumed by miles the writer meant millimeters. That's what I get for assuming instead of asking.

Using all 3 kenko tubes (65mm) on a 50mm, gives you better than 1:1 reproduction.

That might just make these babies worth keeping.

Thanks everyone.