catadioptric Zwiierigkeiten
entschuldigen bitte dass ich English schreibe, Ich habe mehrere CAT objektive, auch ein solid CAT, aber keine bilder die eignet sich für bewertung
The issues of CAT optics has been discussed in several threads here. I have given up on making fair comparisons between my CATs since they presuppose
1:a lack of disturbance in the air between the lens and the object, in particular thermal disturbances can be destructive
2:rocksteady support and exposure,
3:an adequately long sunshade and
4:perfectly set focus ,
none of which is easy to achieve.The standard sunshades usually fail in ensuring enough contrast and focussing must be millimeter exact. And one must assume that original adjustment has been good and not destroyed by amateur cleaning in order to draw conclusions. Also, CAT design differs as to tolerance of different object distance, so to compare like with like requires knowledge of their construction.
The usual complaints about f-Number and out of focus circles (and for some constructions cats-eyes at the edge of the imaging circle) can be avoided by using higher sensor sensitivity and choosing motives carefully. The volume of my Vivitar CAT is certainly more easily portable than the Maksutov i used back in the 1970es.
p.
Zitieren