strmrdr
Super_Ideal_Rock
- Joined
- Nov 1, 2003
- Messages
- 23,295
That is a very interesting parallel to make.Date: 6/27/2009 5:08:21 PM
Author: Serg
Take any nice shot with fine professional camera. Then add dust ( a lot of dust ) on external surface perfect professional lens and take same shot.
You can not see any dust on second photo but quality second photo is worse than quality first photo.
Quality second photo is worse because optical system with dust has worse MTF
Of course less quality camera with same quantity of dust will give worse image. But less quality clean lens could easy give better image than high professional dirty lens
If you have not the shot from clean professional lens you can not understand what other images have some problem with quality.
Diamonds with I1 inclusion ( as a lot of small points spreading in all diamond( due internal reflections) like milkiness ) has worse MTF than clean diamonds with same geometry.
Even you do not see inclusions ( because each point is very small) , all these points together could noticeably reduce diamond MTF. Photos from lens with less MTF have worse sharpness and brightness than photos from lens with bigger MTF
Diamonds MTF depends from facet Flatness too. When cutters want receive good H&A pattern ( high level symmetry) they should use very good polishing disk( low vibration at least), what create better Flatness.
I think( my hypothesis ) what “true H&A“ diamonds have better light performance mainly because such diamonds have very good facet flatness ( better MTF). Parameters are important also of course, But flatness could be more important than high level symmetry .
Some tipe I1 inclusion reduce high score MTF had been created by fine facet flatness . So such diamonds can not have highest MTF and High Light Performance
one of the sharpest lenses I ever owned when it broke and I took it apart I was shocked at the bubbles it had in the lenses.
Dust on a diamond like the inclusions under discussion comes back to the density of the clusters.
A camera in my experience will overstate the effect of dust on a diamond.
I have looked at a diamond, blown on it, looked for dust and not seen anything then snapped a picture only to see it had a lot of very fine dust all over on it in the picture.