Macro... beyond 1:1 - DPChallenge Forums

01/22/2006 03:39:52 PM · #1

So I bought a Teleconverter (2.0x) for two reasons:
- increase my focal length to 400mm on my 70-200mm 2.8 VR.
- increase my reproduction ratio on my sigma 105 2.8 to 1:2 (or 2:1, which ever)

Problem, the sigma and TC-20E are incompatible, the rear glass element of the sigma interferes with the TC-20E. F**k!

Anyway, what should I do? are there any teleconverters that work with the sigma?

How about the Nikon 60mm 2.8. Does it work with the TC-20E?

Thanks for your help...

Brent_Ward

Canon EOS-5D

Canon EF 85mm f/1.2L USM

01/22/2006 03:41:42 PM · #2

Place an extension tube in between the tele and your lens. You'll even get more magnification to boot.

Canon EF 70-200mm f/2.8L USM

01/22/2006 03:53:12 PM · #3

Originally posted by Brent_Ward:

Place an extension tube in between the tele and your lens. You'll even get more magnification to boot.

Can you suggest any extension tubes?

hsteg

Fujifilm X-T20

01/22/2006 03:54:42 PM · #4

Originally posted by labuda:

Originally posted by Brent_Ward:
Place an extension tube in between the tele and your lens. You'll even get more magnification to boot.

Can you suggest any extension tubes?

arent all extension tubes the same, as long as they have metal contacts? other than that, its just a big ring.

kirbic

Canon EOS R5

Canon RF 24-70mm f/2.8 L IS

01/22/2006 04:43:07 PM · #5

The kenko extension tubes are well thought of. I use either a Canon 12mm tube or Kenko 25mm tube between my Canon 2.0x II converter and my Canon 100/2.8 Macro because of the exact same physical interference you're experiencing.
Basically the only consierations with the tubes is whether they have the required contacts to retain lens function, and the quality of the mounts, contacts and tube (rigidity and security).

Canon RF 24-70mm f/2.8 L IS

01/22/2006 04:55:18 PM · #6

Originally posted by kirbic:

Now, how does the focal length of the extension tube relate to magnification? which should I pick?

Does it reduce the minimum focus distance, and hence increase magnification?

Which would be optimal to mount between my TC-20E and my Sigma 105mm for maximum magnification?

kirbic

Canon EOS R5

01/22/2006 05:03:36 PM · #7

The extenson tube increases magnification, simply by moving the lens farther from the mount, thus spreading out the image circle. It also decreases the minimum focus distance which adds again to magnification. The downside is light loss; since you're spreading out the image circle, it's brightness falls with the square of the diameter (linearly with area).
I'd advise buying the set of 3 tubes, you can stack them any way you please to create 6 different lengths.

sir_bazz

Pentax K-5

Pentax FA 50mm f/1.4 AF

01/22/2006 05:12:19 PM · #8

Originally posted by hsteg:

arent all extension tubes the same, as long as they have metal contacts? other than that, its just a big ring.

The Canon extension tubes have L class air in them. ;)

bazz.