Extension Tube Help

[David Billingsley]

I have Canon 12mm and 25mm extension tubes but have never used them - or any other extension tubes. In about two months I will be photographing the very small spring migration birds. The shots will be from a blind and at a distance of about 14 ft. I will be using a 40D and external fill flash when needed.

I plan to use the 500 F4 with one or both of the extension tubes. According to Canon the 25mm tube on a 500 F4 has a focus range of 11 ft to 35 ft. This combination seems to be adequite but not having tube experience leaves me with questions.

Do extension tubes further reduce the already shallow DOF???

Would stacking the 12mm and 25mm be a better choice??? (I don't know the focus range of this combo)

Would a 1.4TC have any place in this set-up???

Any recommendations will be greatly appreciated and would save me a lot of testing.

Have a blessed day - dave b.

[Don Lacy]

Hi Dave, i often use my 500 with extension tubes when shooting Butterflies and Dragonflies and for what you plan to do the 25mm should be all you need but you can stack the 12 if you need it I would let the situation determine the amount of extension used.
Your DOF will be swallower since you will be closer to your subject this is true with or without tubes.
Your 1.4TC will work fine with the tubes just make sure you mount it first then the tube then the lens.
The one thing you do need to be careful of is camera shake from the increased magnification and the all the hardware between the camera and lens.
Hope this was helpful.

[David Billingsley]

Don,

Thanks for the info - greatly appreciated.

dave b.

[Alfred Forns]

David you only use them if they is no other choice. Will loose light and AF performance. I generally skip the 12 and go on to the 25.

You can use the tubes with converters and have seen some wild combinations !!!