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Re: [APML] Orion Mosaic (finally done)
John,
The vignetting could be partly due to the camera back's opening. A Pentax
67 lens mount, for example, causes corner vignetting on my Borg 100ED
scope, but a Planet Town astrocamera with a 4" coupling tube eliminates
this on 6x7 film. My Borg 100ED also uses a 72mm filter.
Dave Kodama
> Wade,
>
> The rear lens on the FSQ-106 is around 72 mm so I don't think adding a
> 72 mm filter makes much difference in the vignetting characteristics.
> The optics with or without the filter does have a noticeable vignetting
> pattern on 6x7 format. One of the first processing steps I take with all
> my 6x7 shots is to flat field the image.
>
> John
>
> Thomas W. Earle wrote:
>
>>John,
>>
>>Thanks for the detailed response.
>>
>>I have two more questions. First, do you have vignetting in the
>>corners due to the 72 mm filter? The diagonal of 6x7 film is
>>approximately 90 mm so logic would suggest you would have it. If
>>so, how much?
>>
>>Thanks,
>>
>>Wade
>>
>>
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>
>
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