scanner lens test

[soldevilla]

A friend has given me a slide scanner that can no longer be used because its drivers are for Windows7 (I hate computers because of these things). I have disassembled the scanner to recover the optics, thinking that a scanner must have a very good resolution to be effective.

I have printed an M42 thread adapter in my 3D and I have tested it. Of course, I haven't been able to respect the original objective-to-chip distance with my reflex, so I get a little more magnification, roughly like a x4 microscope objective, albeit less bright. The result is a surprising absolute absence of chromatic aberration, but a really low resolution. Is this possible simply because of the distance variation between the lens and the chip? I have verified that I have enough tolerance when I vary that measurement with my microscope objectives... Any suggestions? I try again?

[Scarodactyl]

It sounds like you're pushing it way out of its spec in magnification, beyond what it can handle anyway. How close do you have it to the camera sensor?

[chris_ma]

and which scanner was it pulled from?

often film scanner lenses are designed somewhere between 0.5x-1x or 1-2x reversed

[soldevilla]

The scanner was a ENVIVO brand. I don't know the quality.
Maybe you are right. This lens is designed for put a whole slide in a smaller chip. I will test it inverted this weekend

[soldevilla]

Tested! Yes, inverted is great lens!!! At 12mm fov maybe is my best lens in the big center area, without CA. In the borders it have a bit of distorsion.

I will print a new adapter nex week. I tested it at 2.5 mm fov too and perhaps it not have the same resolution that a 12mm, but the field is more flat and the CA not appear. I will test it with the new adapter.