Reverse lens (Fourmulas)

[spmakwana]

If I reverse 50mm 1.8G reverse it on 18-55mm...
what will be the closest focus distance?
Light will decrease by how much f-stops?
What will be the maximum reproduction ratio?

Is there any mathematical formulas to calculate all above things?

 

[spmakwana]

125+ views and no single reply? Question is that tough or what?

 

[manuelian]

Hello Summit, The minimum focus varies according to the lens. May this article will help you in calculation of minimum focus distance Lens Magnification

 

[spmakwana]

Hello Summit, The minimum focus varies according to the lens. May this article will help you in calculation of minimum focus distance Lens Magnification

Ok thanks for the link of article, and do you have any idea about decrease of light by how much f-stops when I reverse Nikkor 50mm f1.8D wide open on 18-55mm at 55mm? and what will be the actual focul length of combine lens

 

[chris]

If you reverse a lens and set it at infinity focus then it will be focussed on a point equivalent to where the sensor (or film) plane would be if it had been mounted conventionally on the camera body, ie probably about 20 - 30 mm from the back of the lens depending upon the lens mount. If the reversed lens is focussed closer than infinity then the plane in focus will be further away from the rear of the mount.