Extension tubes, macro photography and higher maths I shouldn't have skipped.

[TylerW]

Dear Dgrin: what lens should I buy? (just kidding)

Ok, so after oggling much of Awais's macro work, its got me fired up to do some of my own. I don't feel like spending a ton of money, trying to be conservative on buying photo gear for the rest of the year. So I'm wondering, how does an extension tube on a telephoto lens (say,the Canon 70-200mm f/4L) compare to a dedicated macro. Also, clearly the length of extension tube affects the minimum focusing distance, but is there any math to determine by how much? My lens has a min. focusing distance of 1.2m, what would a 12mm tube bring it down to? or the 25mm?

Thanks in advance,

[BigAl]

Using the following search terms in Google:
macro magnification "extension tubes" site:http://photography-on-the.net/forum

yields 640 hits. Of those, the following may answer your question:
http://photography-on-the.net/forum/showthread.php?t=51952

[ziggy53]

Using the following search terms in Google:
macro magnification "extension tubes" site:http://photography-on-the.net/forum

yields 640 hits. Of those, the following may answer your question:
http://photography-on-the.net/forum/showthread.php?t=51952

Good answer! Instructional and informational.

ziggy53

[howard]

I just had a quick check using my Kenko tubes on a 70-200/4 and here's roughly what I/you get.

12mm tube you can fill the frame with an object about 10cm wide
20mm fills with about 6mm.

Not exactly macro but usefull for close up.

By way of illustration here's one from Sunday with all three tubes on a 300/4 slight crop from the sides

http://i.pbase.com/o4/36/547236/1/65105288.nhlcn5EF.IMG_3539.jpg

Here's one from the 135/2 again with all three tubes

http://i.pbase.com/o4/36/547236/1/65105286.58eBxtDQ.IMG_3597sml.jpg



Dear Dgrin: what lens should I buy? (just kidding)

Ok, so after oggling much of Awais's macro work, its got me fired up to do some of my own. I don't feel like spending a ton of money, trying to be conservative on buying photo gear for the rest of the year. So I'm wondering, how does an extension tube on a telephoto lens (say,the Canon 70-200mm f/4L) compare to a dedicated macro. Also, clearly the length of extension tube affects the minimum focusing distance, but is there any math to determine by how much? My lens has a min. focusing distance of 1.2m, what would a 12mm tube bring it down to? or the 25mm?

Thanks in advance,