08-10-2011, 09:58 AM
[quote name='miro' timestamp='1312964621' post='10567']
The problem with encoder is not resolution. We have novadays rotary encoders with 37 bits/revolution. However the accuracy is still counting in percents % /e.g. 0.01...1%typical value /. When you look at high end encoders from Heindenhain you will come back to Ziess. They use the Zeiss high quality glass for their encoders.
However I woud say that there are not extreme expansive – e.g price of 2000..3000Euro for such encoder or target is still acceptrable???
What will be more exaensive is
1. Keep clean target
2. ALignment of Target
3. Alignment of camera
4. Precisision foucus
5. Environmental disturrbanceses. E.g trilling
======================
I have few ideas. But all of them are very expensive.
If you have some ideas how to solve all 5 issues above please let me/us know.
I'm interested of such setup too
[/quote]
I think these issues are solvable. An absolutely clean target is not necessary - only the edge to be measured must be clean.
Alignment is primarily a focus issue and you can refocus for the spot to be measured. That would mostly rely on CD-AF which is usually extremely accurate at least at max. aperture.
It's still a quite hypothetical discussion I think. We just can't afford to put vast resources on this specific aspect. There are further characteristic which are generally more important than macro performance (other than for macro photographers of course).
The problem with encoder is not resolution. We have novadays rotary encoders with 37 bits/revolution. However the accuracy is still counting in percents % /e.g. 0.01...1%typical value /. When you look at high end encoders from Heindenhain you will come back to Ziess. They use the Zeiss high quality glass for their encoders.
However I woud say that there are not extreme expansive – e.g price of 2000..3000Euro for such encoder or target is still acceptrable???
What will be more exaensive is
1. Keep clean target
2. ALignment of Target
3. Alignment of camera
4. Precisision foucus
5. Environmental disturrbanceses. E.g trilling
======================
I have few ideas. But all of them are very expensive.
If you have some ideas how to solve all 5 issues above please let me/us know.
I'm interested of such setup too
[/quote]
I think these issues are solvable. An absolutely clean target is not necessary - only the edge to be measured must be clean.
Alignment is primarily a focus issue and you can refocus for the spot to be measured. That would mostly rely on CD-AF which is usually extremely accurate at least at max. aperture.
It's still a quite hypothetical discussion I think. We just can't afford to put vast resources on this specific aspect. There are further characteristic which are generally more important than macro performance (other than for macro photographers of course).