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# Thread: Leitz minus aberration meaning

1. ## Leitz minus aberration meaning

I found that leitz summitar have negative spherical and coma aberration . Is negative aberration good thing or bad thing and if it is a good thing , how it comes at a picture ?

Umut

2. Mustafa, the only thing I can say regarding this 'negative' formulaic determination is that it just might balance out the other elements. So many elements are used to counter the bad effects of the others. That is why (especially) wide angles have so many surfaces: wides are the most difficult to correct. Read this:

http://www.lensrentals.com/blog/2010...ly-aberrations

- David Lyga

3. David, yes, negative, positive aberrations are used for balance each other. But it opens a new questions , is it explains everything. I have a Ektar ,my mother and I agree , when you look from the back of the lens , skin details, shadows, lines, 3d curves are faraway being increased and visible. Faraway, different than the eye sees. Why ? Are these high aberrations and compensartions used for something also ?

Umut

4. Nomenclature for negative and positive coma and spherical aberration.

Is negative aberration good thing or bad thing
Personally I prefer positive coma, where it seems to point into the picture frame, rather than pointing outward.

5. ic-racer,

Thank you very much, first time I have ever saw such graphs. Can you explain first graph and your preferenment ?

Umut

6. That is interesting about sph. aberration.

Since the effective focal point determines the position of the image for any object, the fact there are several different focal points for the different kinds of rays means that there are several “ghost” images formed by the lens – the “real” one determined by the location of the paraxial-ray focal point, and a number of other images that are formed at different distances depending on where the rays that form them struck the lens.

7. negative coma

when coma is negative, the image produced by the off-axis rays is slightly smaller.

8. Originally Posted by Mustafa Umut Sarac
ic-racer,

Thank you very much, first time I have ever saw such graphs. Can you explain first graph and your preferenment ?

Umut
Positive coma. They point inward toward the center.

9. Originally Posted by ic-racer
Positive coma. They point inward toward the center.
So that's what that is called. My Summitar has displayed this effect, shot at f2 at infinity. I can't say I like the effect at all.

10. How do you analysis below charts of Leitz Wetzlar Summitar Design Analysis ?

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