Re: [APML]: Lunar Interference - Follow-Up - Thanks + Last Question

["Mike Regish" <mregish@map.com>]

I don't think it matters where you place it in relation to the focal
reducer. I have the eyepiece type, so I can't really use mine at all for
prime focus stuff. It does matter that you focus with the filter in place.
That can be difficult since it cuts out so much light. I swing to a nearby
bright star and then swing back to recompose on the original star field of
the object I want.

As for using it with planets, it won't do you much good. The filter is
designed to let the light from emission nebulae pass through while holding
most of the other light back. The light from planets is full spectrum, since
it's reflected sunlight, so I don't think it will really do what you want it
to do.

You don't really need it for planetary work anyway, since you'll be doing
eyepiece projection adn your effective focal ratio will be REAL slow. You
exposures for planets,also, will be only in the range of a fraction of a
second to a few seconds, so you don't need to worry about reaching skyfog
even on moonlit nights. Look at my web page for a shot of Saturn alongside
the limb of the moon. I would've liked to expose for Saturn a little longer,
but that would have just completely washed out the features on the moon.
This is an extreme example of planetary photography with the moon in the
sky, so you can see that you generally don't have to worry about it when
it's in another region of the sky altogether.
Mike Regish
http://members.tripod.com/~mike534
-----Original Message-----
From: EdwardsNo1 <EdwardsNo1@aol.com>
To: astro-photo@nightsky.com <astro-photo@nightsky.com>
Date: Thursday, January 15, 1998 2:34 AM
Subject: Re: [APML]: Lunar Interference - Follow-Up - Thanks + Last Question


>
>Mike, Rod & Philip,
>Thanks for your advice. You have demonstrated to me that with common sense
and
>the correct f ratio it can be worth having a go on clear nights, regardless
of
>that bright Lunar Beacon. You have lifted my spirits and determination to
>succeed in both Deep-Sky shots and Eyepiece-Projection. And as one of you
so
>relevantly pointed out it's good practice anyway, and as a beginner thats
what
>I should be thinking about.
>
>I do have one more question though, that concerns the use of my Lumicon
Deep-
>Sky filter. Are there any scientific reasons for placing this filter BEFORE
or
>AFTER my f 6.3 focal reducer in a prime-focus setup ? And should I use the
>filter in an eyepiece projection setup for the Planets ? (sorry that was
two)
>
>You may have gathered that my site is affected badly by sodium street
lighting
>and there are three Towns around the horizon all about 5 miles away.
>
>Steve Edwards
>