Filter Drawer / Slider for observational astro?

[globular]

Filter drawers (and wheels, etc) seem to be targeted at imaging; and I think I understand why:
*  filter changes are common.
*  spacers are often needed to get optimal focus so why not have a filter drawer doing something useful rather than just a spacer.

However does anyone find them useful for eyepiece observing?

It feels tempting to me to be able to side in a filter, change to another, use no filter, etc all without removing eyepieces, threading filters on and off in the dark, etc.
And maybe focusing is easier?  Am I right that there would be little or no refocusing as filters are added or changed when using a filter drawer?

If this is a good (or not a bad) idea then does anyone know how to do it?
I'm looking at the ZWO 2" M54 Filter Drawer (so there is no narrowing of the clear aperture in my 2" set-up) and was hoping to slot it in between the diagonal housing and the baader clicklock that currently screws into the diagonal.  However I can't seem to find adapters to go from 2" to M54 and back again.

Thoughts?

Edited September 10, 2020 by globular

[Cosmic Geoff]

Filters have obvious uses for imaging, but I can't remember when I last used a filter for visual observing.

[globular]

Found this (from Baader via FLO) so maybe it is a thing to do this after all.

I'll put it on my 'maybe one day' list. At £130 for all the bits it's not cheap.

[Stu]

It is something I’ve tried in the past, but with a filter slide that allowed me to switch between no filter, and one of two others. Totally valid and useful for visual astronomy, switching between UHC and OIII is interesting to see the different features change, and also blinking a filter in and out of the light path can help to highlight planetary nebulae for example.

[globular]

That was my thinking @Stu.

I was just a bit worried there must be some serious flaw, perhaps optically, as no one seems to do it - or rather no company seems to be pushing sales of it for this purpose. I guess they are happy making a living out imagers. (Or maybe I've not been looking in the right places).

[AstroTim]

I’ve also been looking into getting a filter drawer for visual use and have had the same thoughts as you. I currently use a manual filter wheel, but that is a very bulky solution for just swapping quickly between one or two filters during a session. I have been quite surprised at the lack of options, and cost involved compared to filter wheels, which are readily available and relatively inexpensive. I actually suspect that filter drawers are geared more towards visual use (if you regularly want to switch between 3 or more filters then a wheel becomes more convenient) and therefore there is probably much less demand.

 

Tim

[Stu]

26 minutes ago, globular said:

That was my thinking @Stu.

I was just a bit worried there must be some serious flaw, perhaps optically, as no one seems to do it - or rather no company seems to be pushing sales of it for this purpose. I guess they are happy making a living out imagers. (Or maybe I've not been looking in the right places).

The only thing to be aware of really is if they take up too much inwards focus. Normally you can keep them fairly short so should not be a problem but worth noting, especially if you use binoviewers aswell for instance.

Funnily enough, I did a google search and came up with my own SGL thread 🤣🤣

 

[globular]

My scope's optimal back focus is apparently 133mm and with the Baader Prism that I have my eye on having a light path of 100mm (plus a bit for light absorption within the prism glass) I reckon there is a bit of spare space for a filter slider.  I'm not imaging so I don't need to be bang on it.

I did search for 'filter drawer' threads before starting mine, but it didn't pick up your 'filter slide' one.  Small world.  Glad I bumped into an expert!

Edited September 11, 2020 by globular