Re: [APML] Zapping moonlight glow with PS

[Matt BenDaniel <matt@starmatt.com>]

At 03:08 PM 4/2/2002, Emmanuele Sordini wrote:
>At 17.21 01/04/2002 -0500, you wrote:
>>Emmanuele,
>>
>>You can use curves to darken the background. The problem is the loss of 
>>S/N. To get the wispies on film under moonlight, the only thing you can 
>>do is stack. The blue component of moonlight washes out the tail, which 
>>is mostly blue. Sorry.
>
>I'd bet it... but I can not zap the Moon, can I?

You cannot "zap" moonlight in an exposed image. I think the screen/subtract 
suggestion is barking up the wrong tree. Curves are the most useful image 
processing tool and, when properly used, will get all the detail possible 
out of this image.

>it's better a moonlight-flooded comet picture than none at all :-)) And if 
>weather allows for it, I'll have some more chances to shoot the comet in a 
>moonless sky in the next days...
>
>>Or, if you'd be satisfied with B&W film, you could use a swan band filter 
>>during the exposure.
>
>That could make do, but what kind of B&W film should I use? I mean, since 
>I don't have any way of hypering TP or getting a hypered roll, I should 
>turn to such films as T-MAX or HP5. Could it be worth a try?

Hypered Tech Pan is by far the best B&W film for faint objects. Perhaps 
other astrophotographers in your region would hyper for you. But in any 
case the filtering out of moonlight (which was your original question) 
still requires the swan band filter (which costs something like US$200 in 
the 2" size).

--
Matt BenDaniel
matt@starmatt.com
http://starmatt.com


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