nifty fifty and kenko's on my D80...

[DarrenT]

I have had some time to experiment with the magnification this evening and found that my D80s sensor (23.6mm wide) can capture a total width of 16mm at closest focus.

if i worked it out right that puts the magnification at about 1.475:1 which will be fun!

I also found that my Sigma 24-70mm on the tubes would get me about 14mm (1.68:1) but the working distance is so small that the huge 82mm thread looms rather menacingly over the target!

Now if i wanted to boost my numbers further one obvious option would be to extend further, but that would shrink the focusing distance to be right in front of the lens.

does anyone have the numbers on a 105mm fixed with a 50mm reversed onto the front? i have seen images of such arrangements before with some even including teleconverters.

[daft_biker]

Originally Posted by DarrenT

does anyone have the numbers on a 105mm fixed with a 50mm reversed onto the front? i have seen images of such arrangements before with some even including teleconverters.

If you divide 105 by 50 you should get your answer

The longer the lens on the camera and the shorter the reversed lens the greater the magnification ratio.

[DarrenT]

if i worked that out right it came in as 2.1:1 with a 105 and a reversed 50mm.

Its definatly something i'd like to try out i tihnk if i can pick up a cheap 105mm on ebay.

i assume the teleconverter just extends the focus point out a little so you dont have to be so close to get the same magnification?

[PhotoNewt]

Originally Posted by DarrenT

...i assume the teleconverter just extends the focus point out a little so you dont have to be so close to get the same magnification?

Actually a teleconverter is a magnifying element that usually goes between the lens and the camera optically increasing total magnification of the lens, producing the field of view of an equivalent longer focal length unit. A 100mm lens with 1.4x teleconverter will have the same field of view of a 140mm lens.

A teleconverter will increase your magnification, decrease your DOF at any given aperture and decrease the light reaching the sensor (a 1.4x will cost you one stop, a 2x will cost you two) but will not change the minimum focusing distance of the lens.

An extension tube placed between the lens and the camera will move the focus plane of any lens forward of the sensor forcing the lens to get closer to the subject to achieve correct focus. This will magnify the subject by decreasing the minimum focusing distance and reduce the DOF as well.

[DarrenT]

ahh, thanks for that PhotoNewt!

After daft_bikers comment earlier i realised that my 70-300mm vr with the 50mm 1.8 on the front could also be worth a try. i would imagine the images wouldnt be as crisp as the 50mm with kenkos but it'll allow a much higher magnification so its definatly something i'll experiment with.