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Astrocrumb Filter Slide for Dobs with a FT focuser

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#1 Olivier Biot

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Posted 01 July 2010 - 03:59 PM

Assembly of the new Astrocrumb Filter Slide for Dobs with a Feathertouch focuser

#2 Howie Glatter

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Posted 04 July 2010 - 08:10 AM

I was out last night at an observing session of the Catskill Astronomy Club at Walnut Mountain, Liberty, N.Y., and Rob Teeter was there with an 18" f/5 with a Zambuto mirror that he was testing before delivery to a customer.
It had an Astrocrumb filter slide installed, and although I've observed with many Dobs that had them, this CN report prompted me to think about the great utility of this accessory. The fact that it eliminates all handling of the filters (saving them from accidents and fingerprints), and lets you rapidly switch to find the best filter for the particular object being observed, makes it a wonderful adjunct indeed, especially for planet and nebulae freaks.
The quality is superb, with very smooth action and secure detents without backlash.

Howie

#3 davidpitre

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Posted 04 July 2010 - 02:23 PM

Paulo,
You did a nice job explaining the set-up and function with your images.
You also have a beautiful telescope.
The Astrocrumb Filter Slide looks like it would intrude substantially into the light path unless you have an exceptionally large secondary cage.

#4 Roger Greenwood

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Posted 04 July 2010 - 11:33 PM

David,
You are correct that it intrudes into the light path. What I tell people is that while a star test will certainly show such an intrusion, actual observing isn't affected enough for it to be an issue. The trade-off, of course, is for being able to click instantly between all your filters. I don't usually recommend it for Dobs smaller than 12.5 inches.

-Roger

#5 RapidEye

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Posted 09 July 2010 - 02:11 PM

The Astrocrumb Filter Slide looks like it would intrude substantially into the light path unless you have an exceptionally large secondary cage.


I installed one of Roger's slides a couple of months ago and have been pleased as punch with it! Like you pointed out, it does intrude into the light path, but on my 18" f/4.5 Obsession, it isn't enough to effect the views of DSO's (which is where you primarily use filters anyway).

For planetary work where subtle changes in contrast can be very noticeable, it takes all of 1 minute to remove the slide from the focuser and when you are done, all of 2 minutes to reinstall it.

Typically where I observe in the Mid-Atlantic region of the US, seeing is the primary limiting factor for planetary work and in practice, I've not seen any degradation in the view due to the slide. :cool:


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