Reversing 50mm?

gardenersassistant wrote:

3D Gunner wrote:

gardenersassistant wrote:

What is puzzling me here is the "as long as", which presumably means the lens can't focus if it isn't at the proper distance from the sensor. However, if your options 1 and 2 put the lens at the right distance from the sensor so it can focus, how is it that the reverse to body option I used also allows the lens to focus, with it being at the wrong distance from the sensor? I used

3. m4/3 body + reverse ring + reverted lens

which puts the reverted lens closer to the sensor than your options 1 and 2.

It's about the minimum distance required between the lens and the sensor.
The adapter between different mounts provides the minimum distance needed (at least).
Using the bayonet-to-lens-thread adapter requires a few extra extension rings to get the minimum distance needed for imaging on the sensor.

I just mounted a Canon EF-S 18-55 reversed directly on to a reverse ring on a G80. Both have 58mm threads so no extension rings were needed to make the physical connection. It focused fine all the way through from 18 to 55mm. I then did the same with a Panasonic 14-140mm (the only other lens I have with a 58mm filter thread). It too focused fine without the need for any extension rings.

The m4/3 will focus with the lens reversed directly to the body, but a prime lens doesn't get the appropriate magnification. You need to use a prime to test. A 50mm prime should be 1:1 when reversed.

See what you get when you reverse a 50mm prime directly to the body. Even with the adapter, it still seems to need a few mm extension to be accurate. It's around 30mm from the body to the face of the lens.