Re: [APML] AP 130/F6 LPR filter help

[Chris1011@aol.com]

In a message dated 2/22/2001 11:54:38 AM Pacific Standard Time, 
Matthias.Felsch@t-online.de writes:


> >>Is it a reflection inside the filter (between the two surfaces), or is it 
> rather one between thefilter and the field flattener (or both?)? >>



Reflections can only occur between two parallel surfaces. The field flattener 
has a curved surface, so any light relected off that surface would diverge so 
rapidly, as to be totally out of focus by the time it reaches the film plane. 
Also, the field flattener has a very low reflection multi-coat, < 0.2%, and 
would not reflect back any meaningful amount of light.

> >>Does the place of the filter in the light path or the distance between 
> filter and flattener have any influence on the amount of ghost images?>>



The flattener does not produce ghost images with the filter. Makes no 
difference where the filter is located, it will by itself produce the same 
ghost image. In fact, you could place it in front of the telescope, and even 
tilt it, yet it will produce the same ghost image (assuming the filter has 
flat surfaces). That is just the way it is with optics.  

Roland Christen

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