Stacking macro lenses

[Scotttyd]

Simple, but maybe a dumb question. If I stack macro lenses is the magnification additive or exponential? Ex. if I have two 10x magnification lens (not sure what the actual magnification is) and I stack them, do I have 20x magnification or 100x?

I just got my first Inon macro lense UCL165, and was curious as to what happens when I stack them (Herman can tell you what happened the one time I tried, as the camera didn't quite make it to the water).

 

[alijtaylor]

Good question, I'm interested in the answer too. I have 2 UCL 165s and only use them together because with only one it doesn't do much. I suspect from experience that it is additive but I don't know enough optics to back that up.

Alison

 

[bvanant]

Somewhat less than additive and certainly not multiplicative. Do the experiment, shoot a dime full frame with your camera then add the diopter then add the second one. The big issue will be DOF which will get very tiny very quickly
Bill

 

[Scotttyd]

Somewhat less than additive and certainly not multiplicative. Do the experiment, shoot a dime full frame with your camera then add the diopter then add the second one. The big issue will be DOF which will get very tiny very quickly
Bill

Thanks - I only have one lens right now - couldn't experiment on my own - yet.

Out of curiosity, does anyone have example of the same pic, with no macro, 1 lens and then two? I remember seeing one on somebody (one of the dealers) web site, but I cannot remember.

 

[herman]

Scotty mine are working this week but we can get together some time and do some experimenting...although the pool is a better option now.....as long as you promise to be careful with them...no more camera fires!

Folks in all seriousness, be careful with macro lens, esp when you stack them. Scotty borrowed mine, set his camera down lens up and pretty much instantly melted his camera's shutter. High power magnifying glasses and the sun are a powerful mix, there are thousands of ants that can attest to that fact.
Dove a new site today Scotty, 2 turtles (one very cooperative), a huge school of bait fish and a baracuda that was huge.. It will be on our todo list in June.

 

[herman]

Oh, and they add. 2 x 10 diopters become more or less 20 diopters. The biggest issue you will face is depth of field, it gets somewhere in the 1/2 to 3/4 inch range when you stack 2 165's. Makes a nice photo but focus and composition is critical, being off 1/4 of an inch is not acceptable.

 

[shoturtle]

You will also make it very sensitive to camera shake, it may get a point where even an IS camera can not compensate for it. I know that when you stack TC's to DSLR lenses you bring down your aperture. If you start with a F2 lens adding a 2x tc will make it a f4 lens. And the more TC you add the smaller it gets and you get more camera shake. You may be creating more problem, just a thought.

 

[AndyT]

If I remember correctly the Inons are a +6 diopter. Two should theoretically give you +12.

Don't confuse diopters with TC's - diopters will allow the camera to focus closer to the subject but will also shorted the focal range considerably. Diopeters will not change the aperture, but you do lose 1-2 stops of light owing to the extra glass involved.

When used with a longer focal length finding the subject in the first place can be quite difficult ! Then there is the aforementiond depth of field issue. I generally find it is better to switch to manual focus and when you find the subject rock the camera back and forth untill you get a sharp image in your LCD / viewfinder.

Scotty, I think this is the link you were looking for?

Reef Photo & Video Support Center - KnowledgeBase - How much magnification will the INON UCL-165 lens yield?

This was taken with a 50mm macro, 2x TC and two Inon 165's

 

[gravity]

Also, don't get confused between 10X and +10. A plus +10 diopter does not provide 10X magnification. The level of magnification it provides is dependent on the focal length you are shooting at. For instance on a 60mm macro lens, it provides about 40% magnification. On a 105mm lens, it provides about 2.2x magnification.
It is possible to stack them, but the practical benefits disappear quickly. A +10 diopter (macro lens) has a maximum focus distance 100mm from the center of the lens. For practical purposes +20 diopter would have a maximum focus distance somewhere inside the macro lens. So there is an upper limit to its usefulness. reefnet.ca has a useful calculator for determining how much magnification you will get based on the focal length of the your lens and the strength of the diopter.

 

[Scotttyd]

Scotty, I think this is the link you were looking for?

Reef Photo & Video Support Center - KnowledgeBase - How much magnification will the INON UCL-165 lens yield?

exactly, thanks, that puts things a little more in perspective for me.