Are shrouds unavoidable?

If shrouded viewing is unavoidable, then I will make a shroud.

However, my cage blocks out all light from the top of the cage to the focal plane. But from the bottom, I can see some ground (crescent) with the eyepiece removed and looking at a sharp angle down through the fully racked in moonlite focuser. I wonder what the practical effect will be when I'm done. Is this normal, or better or worse than average? I've seen a lot of cages with the focuser right at the bottom of the cage, and having tested that position too, I can see a full circle of ground, not just a crescent as seen in my sketch below. My sketch is really my cage and dimensions, and about as high as I can get the focuser without more aggresive measures.

So, Should I worry about this? Is a shroud necessary anyway? will a filter slide/focuser baffle eliminate the need for a shroud? anyway what do you guys think?

Thanks for sharing your thoughts on baffling/shrouding.
TomL

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A shroud is not needed if you are always at a dark site without side lighting. If you are at a site with lights, it would be helpful.
Floyd

I'm not sure you could baffle enough at the focuser or with a filter slide without adversely affecting the light path from the primary.

BTW what did you use to create that drawing? It's very nice.

Thanks Craig, the program I use is for the macintosh, and it is a CAD-like program called sketch up. I purposely use the jagged line renderer as opposed to the precise lines as I feel it takes the cold computerness out of the CAD process, without sacrificing too much accuracy. I'm sure you agree.

TomL

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You don't necesarily need a full shroud. You should put a baffle below the UTA opposite the focuser so you can't see that slice past the UTA. Other places for a baffle are a ring behind the primary, and in front of the focuser. Read the stuff on Mel Bartel's pages about the minimal baffling necessary: http://members.efn.org/~mbartels/tm/ul-dobs.html

Jarad

The nice drawings are useful, but it is still more
complicated. Nagler eyepieces -- like the 17, 26, 31,
etc. -- have a negative lens that sits way down below
the focal plane near the bottom of the 2" barrel.
This lens will suck in stray light, even if
you can't see any looking in the focusser.