Extension tube test

I posted this in the macro forum also, but it actually might be a better fit in one of these more general forums, as everybody there is mostly using real macro lenses!

Kind of a dreary day out there, so I decided to do a little test. This was mainly for my own knowledge, but figured I would post the results on here for anyone who is interested! Not too long ago I got a set of Vivitar extension tubes, and wanted to figure out what kind of results I could get with my different lenses.

I tried out my 50 1.8, 85 1.8, and Sigma 70-300 3.5-5.6. All photos were shot at f8.0, 1/160, and ISO 800. Using the extension tubes changes the exposure, so I tried to make them about equal in exposure in LR5. I was surprised that there seemed to only be about 1-1.5 stops of light lost when using the full set (65mm) of extension tubes.

Here was my set-up, just a penny sitting on my subwoofer! All shots were handheld, just because my distance varied to much from shot to shot, it would have taken more time than I wanted too!

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98025​26374/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​97956/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​97706/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​97286/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​63355/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​96806/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​96696/

Now here's the from my Sigma 70-300 APO Macro ("macro" in the 200-300 range) Here it is @200mm with no tubes. MFD according to the distance scale on the lens is .95 meters.

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​95846/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​95736/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98024​42553/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98023​86604/

IMAGE LINK: http://www.flickr.com/​photos/davidmtml/98025​26464/

davidmtml wrote in post #16309740
To start off.
Here is the 50mm bare, MFD is ~1.5ft.


Here is the 50 with just the 21mm tube, which brings the MFD down to about 6 inches.

Wow. Just the addition of a 21mm tube brings your MFD from 18 inches all the way down to 6 inches - that's awesome!

My 400mm's MFD is 10 feet - when I put my 25mm tube on, the MFD only gets down to about 7 feet . . . not much of a difference at all.

I think it's great that you experience such a dramatic difference with your tube/lens combo. I'm disappointed with mine.

Tom Reichner wrote in post #16310626
Wow. Just the addition of a 21mm tube brings your MFD from 18 inches all the way down to 6 inches - that's awesome!

My 400mm's MFD is 10 feet - when I put my 25mm tube on, the MFD only gets down to about 7 feet . . . not much of a difference at all.

I think it's great that you experience such a dramatic difference with your tube/lens combo. I'm disappointed with mine.

Ya, it really just depends on focal length. It takes a lot of extension tubes to make much of a difference on a 400mm!

If the lens focus is set to Infinity, then 1:1 is achieved when Extension = FL
Stated differently, Reproduction Factor = Extension:FL

That is why you cannot get as close in using same extension tube with longer lenses.

50mm extension on 50mm FL = 1:1
50mm extension on 100mm FL = 1:2
50mm extension on 200mm FL = 1:4

Wilt wrote in post #16313180
If the lens focus is set to Infinity, then 1:1 is achieved when Extension = FL
Stated differently, Reproduction Factor = Extension:FL

That is why you cannot get as close in using same extension tube with longer lenses.

50mm extension on 50mm FL = 1:1
50mm extension on 100mm FL = 1:2
50mm extension on 200mm FL = 1:4

You're supposed to add the native MM on top of the increase, aren't you Wilt?
For example.. 50/1.8 II(native MM =.15x) w/ 50mm extension would equal ~1.15x (.15x + 1.00x).

1Tanker wrote in post #16313371
You're supposed to add the native MM on top of the increase, aren't you Wilt?
For example.. 50/1.8 II(native MM =.15x) w/ 50mm extension would equal ~1.15x (.15x + 1.00x).

That is if you want to determine the MAXIMUM magnification with the combination. I provided the calculation of the minimum magnification with the combination...the lens focus set to Infinity. Put a different way, true macro work for scientific/engineering purposes wants some degree of precision, and with lens at Infinity you get that; with lens focus closer, you have some greater difficulty in calculation a reproduction (unless you know MFD and set the lens to that)

1Tanker wrote in post #16313371
You're supposed to add the native MM on top of the increase, aren't you Wilt?
For example.. 50/1.8 II(native MM =.15x) w/ 50mm extension would equal ~1.15x (.15x + 1.00x).

This is what I thought too!

Wilt wrote in post #16313594
That is if you want to determine the MAXIMUM magnification with the combination. I provided the calculation of the minimum magnification with the combination...the lens focus set to Infinity. Put a different way, true macro work for scientific/engineering purposes wants some degree of precision, and with lens at Infinity you get that; with lens focus closer, you have some greater difficulty in calculation a reproduction (unless you know MFD and set the lens to that)

Thanks for this Wilt, I did not know either!

Wilt wrote in post #16313594
That is if you want to determine the MAXIMUM magnification with the combination. I provided the calculation of the minimum magnification with the combination...the lens focus set to Infinity. Put a different way, true macro work for scientific/engineering purposes wants some degree of precision, and with lens at Infinity you get that; with lens focus closer, you have some greater difficulty in calculation a reproduction (unless you know MFD and set the lens to that)

Ok..gotcha. Thanks!