Hi Mudsab 

 In my opinion, the tolerance items manufactures use to calculate the f and the ones you use may be different. Since from the site, only dimension tolerance can be got. Other information ,say n tolerance, is not released to public.

best regards 

Yang

Wavelength variation?  Not sure what you mean…. 

If you buy an achromat designed for use in the visible, then you might be using it at a wavelength anywhere from 425 nm to 675 nm.  The measured focal length will change with wavelength, and my assumption is that this focal length variation is part of the tolerance spec.  Otherwise, it’s hard to see how the focal length can change by +/- 1% with only fabrication tolerances (when measured solely at the design wavelength).  However, I can’t find an exact definition of Edmund’s focal length tolerance.

Jeff 

Thank you for the replies!

That’s a good point that you raise Jeff. I didn’t consider that the tolerancing is really only considering focal length variations as a direct consequence of manufacturing and not the variation you would see across the visible wavelength band.

I’ve checked the best and worst case monte carlo files and used some EFFL operands to check the focal length at the F,d,c spectral lines. Taking that into consideration the +/- 1% specification makes more sense now!

Musab