Nikkor M ring ?
I was the lucky bidder on a couple of lenses. One of which was an Auto H 50/2. It came with a M ring attached and in a presentation case. I can only seem to find information regarding the M ring + the 55mm lens. From what I gather the 27.5mm ring attached to a 55mm lens produces a macro 1:1 ratio.
so true or false?
if 55 mm + 27.5 = 1:1
then 50mm + 27.5 = <1:1 (1:-.975)
if the answer is false...please explain.
I assume that you mean the use of a 55mm lens on 27.5mm extension tube.
If you leave the lens set to infinity the magnification of 55mm + 27.5mm = 82.5mm is 0.5X.
You can increase the magnification by extending the lens forward further on its focusing helicoids.
A standard lens, such as the 55/1.2 AI has a maximum forward extension of about 4.8mm. In this case the magnification can be increased to about 0.58X.
A 55mm Micro Nikkor has about 27.5mm of helicoids extension that obtains 0.5X magnification by itself without tubes.
So by extending the 55 Micro Nikkor fully when mounted on a 27.5mm tube we get 1X (usually written 1:1) magnification.
With a standard 50mm lens at infinity focus the 27.5mm tube gives us 0.55X.
Since this lens only produces about 4.8mm of helicoid extension, when its mounted on the 27.5mm tube and fully extended we get 0.65X.
The key factor in determining the magnification is exactly how far forward of its infinity position the lens can be extended.
In all cases, the magnification is
m = i/f - 1
where i = the distance from the optical center of the lens to the film and f = focal length.
Thanks Ian. I'm totally confused. Just have to try it as is..with the 50mm attached to it. But the information on the web indicates that the M ring was the "usual" accessory to the 55mm lens which I do not have. The information stated that the macro with the 55 would be 1 to 1 and nothing was said about infinity or extending lens which would be longer reach than infinity? I dunno. So .065x = macro of 1:.065. ----- my fuzzy math was incorrect. More to learn. Thanks again. out of 80 views your the only one to answer and is much appreciated.
p.s. I'll print your response and save it in my camera note folder.
The 55mm Micro-Nikkor when used with the M ring, will focus from half lifesize to lifesize. Without the M ring, the Micro-Nikkor 55mm will focus from infinity to half lifesize.
Other lenses in the 50-55mm range are a different story. The M ring was an accessory for the 55mm Micro-Nikkor, not the other 55mm lenses.
The M ring will also allow you to focus more closely with a telephoto lens. But, that's not what is was technically designed for. =)
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I use tubes for tighter headshots w/tele's all the time.
as long as you dont get too close with a shorter lens (perspective distortion) it works great
For more info than you ever wanted on Nikon extension rings.
I have a Nikon M2 (27.5mm) extension tube that I use with a:
55mm f/3.5 macro lens for 1:1 shots
180mm f/2.8 lens for tight face shots
Nikon body that has a grip that interfere with mounting the body on a bellows unit
M rings are often way cheaper than the other 27.5mm tubes, too. Very useful.
Originally Posted by narsuitus
The clearance issue is a pain. Too bad Nikon never built them with a rotating tripod collar like the PN-11.