2" Filter placement in imaging train

[oymd]

Good day everyone.

Can you please advise how to fit a "2 filter in my imaging train?

My setup is:

Evostar ED80mm ===> Focal reducer ===> ZWO 16.5mm extender ===> ZWO 21mm extender ===> ASI294MC Pro

I have been advised to get the ZWO 2" filter drawer, which is 21mm, and replaces the ZWO 21mm extender.

With the virus outbreak, shipping times are forever, and it isn't in stock at FLO or 365, I would rather try another solution for the time being?

I threaded the filter onto the back of the reducer, and threaded the 16.5mm extender to the other side of the filter, but it did not screw on properly, and it was a very weak connection, and might possibly damage the filter, so I did not proceed with it.

Is there any alternative option to the ZWO filter drawer for 2" filters? (also other than a filter wheel)

Many thanks

[Waldemar]

I think you were advised well... patience is a good thing these days.

You could image without filter while it is on it's way to you, it is a color camera anyway... If light pollution is in the way, try more shorter subs.
Depending on the thickness of the filter, you will need some adjustment shims as well. 1/3 of the filterglass thickness is standard.

[oymd]

Just now, Waldemar said:

I think you were advised well... patience is a good thing these days.

You could image without filter while it is on it's way to you, it is a color camera anyway... If light pollution is in the way, try more shorter subs.
Depending on the thickness of the filter, you will need some adjustment shims as well. 1/3 of the filterglass thickness is standard.

Thanks for your reply.

So without that drawer, there is absolutely no other way in the time being?

[Laurin Dave]

Try this  https://www.firstlightoptics.com/pro-series/astro-essentials-filter-cell-adapter-for-sky-watcher-ed-series-flatteners.html

[Waldemar]

Like you said if screwed into one of the extenders, you will ruin your focal distance with the focal reducer, or skip that one in the mean time.

[gorann]

You can run the camera without a filter but you may get bloated stars since the camera lacks an IR/UV filter (at least my ASI071 lacks it) and your scope is probably poorely corrected outside the visual light spectrum (400-700nm). With my Esprits I noticed that it works quite well without a filter but maybe not for the less well-corrected Evostar.

PS. TS also sells some filter sliders, like this one, but you will need to adjust with T2 rings to get the correct distance to the chip.

https://www.teleskop-express.de/shop/product_info.php/info/p10475_TS-Optics-M48-Filter-Changer---strengthened-Design.html

Edited April 27, 2020 by gorann