Reverse mounted lens

[Cal Stanley]

Nikon D300
24mm lens reverse mounted

US one dollar bill -
http://www.flickr.com/photos/calstanley/4101898792/sizes/l/in/set-72157613428449139/

Cal

 

[Hamish Gill]

That's what I was going to say ... I have mounted a 50mm reversed onto another 50mm and got this

Same sort of idea?

 

[Cal Stanley]

Nikon makes a "Reversing ring" - the BR-2A that has the same configuration as the camera end of the lens on one side and a 52mm male thread on the other. Screw the ring on the filter thread and then mount the lens by the adapter just as you would a regular lens. They also have a BR3 ring that then mounts to the exposed rear end of the lens for protection of the rear element. I'm not sure if you can thread a filter onto that one or not. The shorter the prime lens, the greater the magnification.

Mounting a lens in reverse to the front of a mounted lens using reverse mount rings as above is another great way to get macro shots. The big difference is in what you need for lenses. The image size on the sensor then becomes either the f/l of the mounted lens divided by the focal length of the reversed lens, or just the opposite - the f/l of the reversed lens divided by the f/l of the mounted lens.

 

[Cal Stanley]

One point I forgot to mention - I'm talking about old glass here - lenses with aperture rings so you can stop down to take the shot.

 

[Paul Lange]

I've just had my reverse lens adapter delivered the other day. I also bought an old Canon lens on Ebay but had to send it back as it has a dirty great chip on the rear element. I'm still getting my head round the magnification but I think basically that if you back to back 2 lenses of the same focal length you don't get an increase in magnification but you do get a closer working distance and something approaching 1:1. In regards to getting an actual increase in magnification I'm not sure yet as everything I have read so far has been badly put.

Carl, can you elaborate?? I think what I had read so far is that to get a magnification the reverse lens needs to be a shorter foal length that the lens on your camera.

 

[Cal Stanley]

Hi Paul,
It's Cal, not Carl - but I've been called worse

I just did a quick check with my D300 and a couple of old lenses - a 50mm and a 24mm. With the 50mm on the camera and the 24mm reversed in front of it, 4 letters of a word in bold type on a business card filled my viewfinder. With the 24mm on the camera and the 50mm reversed in front of it, I could see all or most of the card, but the vignetting made it hard to tell.

Getting back to my earlier post, I think I was right in my first description - the image scale or magnification factor is roughly equal to the focal length of the lens mounted on the camera divided by the focal length of the lens reversed in front of that lens. In my example, I had a 50mm on the camera and a 24mm reversed in front of it giving me a roughly 2:1 magnification. That is - the image size on the camera's sensor is twice life size. And you're right - the longer lens is mounted on the camera.

 

[Paul Lange]

Oh, so it is. I misread it!!

Thanks for that, I plan to get a lens to reverse mount to my 85mm Macro (its the only prime lens I have & also the only one without a huge front lens) As its 1:1 anyway I didn't want to go completely OTT wit the magnification.