Nikkor 105mm macro lens and extension rings

Vixen

Vixen

Senior Member
I did this to see what extra I could get by putting extension rings behind my 105mm macro lens
I had to do it handheld as I don't have a fine adjustment setup for my tripod so the focus is not fantastic, but looking at how much of the coin is visible, you can see how much closer you can get to the subject (in this case the match head)

so....with just the 105mm lens (at effectively 157mm on my D7100 acc to the exif data). I didn't change ANY camera settings and focused by moving the lens closer.

DSC_4903_zpsbb01f1a4.jpg


add in a 12mm extension tube

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with a 20mm extension tube

DSC_4906_zpsad487e23.jpg


with a 36mm extension tube

DSC_4908_zpsbca9db5d.jpg


You can of course also stack the extension tubes on top of each other to get in even closer.
 
G

Geoffc

Senior Member
gqtuazon said:
No. It just allows the lens to shoot closer to the subject.
Click to expand...

I think what it does is increase the focal length whilst maintaining the closest focussing distance, at least that's how it behaved when I tried it. Therefore the magnification increases.


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4

480sparky

Senior Member
FastGlass said:
Nice. I'm curious. Does using extension tubes take away stops like TC's?
Click to expand...

Yes. It has to... the aperture blades are further from the camera.



Geoffc said:
I think what it does is increase the focal length whilst maintaining the closest focussing distance, at least that's how it behaved when I tried it. Therefore the magnification increases.


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Click to expand...

Focal length cannot change as there's no glass in extension tubes. Only TCs can change the focal length.
 
F

FastGlass

Senior Member
O'k, I recieved two different answers regarding if adding extension tube rob light thus taking away a stop of light give or take. The more I think about it I would have to agree with 480Sparky. Sorry gqtuazon. To me the further away a hole is from a given point the smaller it appears. So by adding extension tubes your putting the aperture blades further from the sensor allowing less light to reach it. I think.
 
Vixen

Vixen

Senior Member
FastGlass said:
O'k, I recieved two different answers regarding if adding extension tube rob light thus taking away a stop of light give or take. The more I think about it I would have to agree with 480Sparky. Sorry gqtuazon. To me the further away a hole is from a given point the smaller it appears. So by adding extension tubes your putting the aperture blades further from the sensor allowing less light to reach it. I think.
Click to expand...

When I took those pics, I was in manual mode so NO settings at all were changed on the camera and all are exposed approx the same if you look at them. OK, I was out in bright sunlight at the time. I can't go back and tell you the settings coz I deleted the originals...not exactly keepers are they? :D

This may answer your questions tho

How Extension Tubes Work for Magnification - For Dummies
 
G

Geoffc

Senior Member
480sparky said:
Yes. It has to... the aperture blades are further from the camera.





Focal length cannot change as there's no glass in extension tubes. Only TCs can change the focal length.
Click to expand...

From what I've read it does increase the focal length, in that the optical centre of the lens is now further from the sensor. It certainly increases magnification for the same lens to subject distance.


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4

480sparky

Senior Member
Geoffc said:
From what I've read it does increase the focal length, in that the optical centre of the lens is now further from the sensor. It certainly increases magnification for the same lens to subject distance.


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Click to expand...


Focal length is determined by measuring from the focus center to the focus point, using parallel light beams. When you focus a lens closer, the focused light beams are no longer parallel... they converge in front of the lens at the same distance the subject is.
 
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