Magnification with an extention tube or extender

[Ronald Zigler]

According to Canon, one can enhance the magnification of their 300mm f4 lens by adding either an extension tube or an extender. By adding the 25mm extension tube, one raises the magnification from .24 to .37. However, Canon also indicates that by adding the 1.4 TC you can increase the magnification from .24 to .33. My question is this: would there ever be an advantage to adding both the extension tube and the TC at the same time? Or, would the longer focal length of the TC reduce or neutralize the effect of the extension tube?

[John Chardine]

Hi Ronald- The quick answer is no I don't think so. The lens-tc combo is just another lens. The extension tube will allow you to focus at a closer camera-to-subject distance, and therefore gain more magnification with or without the tc, at these closer distances.

[Roger Clark]

Hi Ronald,

Yes, you can do both for a little more magnification, but 25mm extension on a 300 mm lens is not a lot. Also, the combination is beyond the lens design so you may not improve resolution on the subject much. I think I've tried this with a 300 f/4 + extension tube + TC without much improvement in detail on a subject, but if I remember right it was with a 2x
TC.

Roger

[Ronald Zigler]

Thanks for you reply Roger. What would you recommend in terms of extension tubes? That is, how many might one be able to stack together to optimize the 300mm f4 as a "macro" lens substitute? I read that since there is no glass in the extension tube, one may not need to use a Canon brand extension tube. However, if one were to use another brand, like Kenko, would autofocus work as well?

Hi Ronald,

Yes, you can do both for a little more magnification, but 25mm extension on a 300 mm lens is not a lot. Also, the combination is beyond the lens design so you may not improve resolution on the subject much. I think I've tried this with a 300 f/4 + extension tube + TC without much improvement in detail on a subject, but if I remember right it was with a 2x
TC.

Roger

[brian simpson]

I use kenko tubes on my nikons no problem everything works even VR. I dont think going beyond 50mm is a good idea. I think you would need 300mm of tubes to get 1 to 1 true macro,,How do you support that.. two tripods? have you thought of trying a diopter? Or better yet the amazing Canon 180,3.5 macro,,,

[Ronald Zigler]

Thanks for the guidelines Brian. I wish to avoid the extra expenditure of a macro lens. What I like about the Canon 300mm f4, is its versatility that is made possible by combining it with the extension tube or a teleconverter; as well as the quality of the lens when used alone. Thanks again.

[brian simpson]

Yes ive had the canon 300 f4 since the day it came out a true keeper lense..I have been really suprised at the qaulity when using the new 2x canon converter,,,I call it my butterfly setup,,also great for dragonflys.. But AF on pro cameras only,,, Canon ext tubes are stronger but kenko are alot cheaper ,,

[Ronald Zigler]

So you think the Canon "III" teleconverters are really that much better than the less expensive "II"? For both the 1.4x and the 2.0x? Have their been any technical reports based on tests?

[brian simpson]

NO,,,I ve only heard that the 1.4s are about the same, and the new 2x is a little better.,,,I just thought i should get the best being at 600mm need all the image qaulity i can get and only couple hundred bucks more,,