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OSC filter wheel


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Considering getting an l-extreme filter for my OSC. Wondering if I should get a manual filter wheel so I can use a smaller filter and also make changing to a LP filter easier and means less handling of the filter. Anyone else doing this? 

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Haven’t done myself but I think that should be fine. Why would a FW allow the use of smaller filters? I would have though the filters would be further from the sensor if placed in a wheel? (Assuming you normally put a filter on the nose of the cam)

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47 minutes ago, CraigT82 said:

Haven’t done myself but I think that should be fine. Why would a FW allow the use of smaller filters? I would have though the filters would be further from the sensor if placed in a wheel? (Assuming you normally put a filter on the nose of the cam)

My filter screws into the reducer, 2" filter. Just thought I could save a few quid with 1.25" filters as the filter wheel will be screwed to the camera

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I used to use a 2" filter wheel with my DSLR before which worked fine.

I've since moved to a ASI 1600MM with 1.25" filter wheel. It's supposed to get the filter close enough to avoid vignetting but I haven't found that to be the case. Vignetting is mostly removed with flats though.

I think the 294MC sensor is marginally bigger than the 1600MM so would expect similar vignetting (and removal)

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With a ZWO filter wheel, mounted straight onto the camera, you can get away with 1.25" filters. There will be a small amount of vignetting, but flats will remove it completely.

Be aware though, not all 1.25" filters are created equal! Some have smaller clear apertures than others - my Astronomiks have a clear aperture of 27mm, but my old ZWO ones, only 24mm. The ZWO ones caused hard vignetting due to the frame introducing, this could not be removed by flats. 

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I started off with the 1.25" L-eXtreme in the adaptor, but soon got tired of removing the camera to change the filter. So I ended up going with the ZWO Filter Draw and got the 2" Askar Duo-Band filter instead.

I now have the 2" Astornomik L-2 UV/IR Block for broadband and I recently acquired the 2" L-eNhance for when I don't want the full blown Duo-Band.

The filter draw suits my needs because I generally don't change filter mid-session and there's no chance of getting vignetting with the 2 " filters on the ASI294MC. ;)

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One negative of imaging with a manual filter wheel is they tend not to be very light-tight. The filter drawers and EFW's are much better in this respect.

You might get away with a 2" to 1.25" reduced in the image train.

Astro Essentials 2" / M48 to 1.25" Filter Holder / Adapter | First Light Optics

I can't really comment on the 1.25 filters with a 294 sensor though. As stated above , it should be as close as possible. From memory the ED80 FF/Reducer allows filters to be screwed in on the scope side of the flattener which may cause a vignetting problem.

 

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I think it's wiser to remove the camera from the scope and just put the cover over the sensor when shooting Darks. If you build a Darks Library then you only have to do it once, unless you start to notice they're not working. I setup a plan in APT on a cloudy day, put the sensor cover on, sit the camera on the sensor cover (so it's pointed down) and create 30 Darks of each exposure setting I'm likely to use. Once the library is created then I reuse the Darks for the rest of the season.

With the filter draw, here's what I found with mine:

I now have a second filter draw, complete with the "lip" for my filters and I don't get any light leaks when imaging. ;)

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L-pro and L-extreme in the filter wheel here, with the asi 533 mc pro. 
because i wasn’t sure about vignetting, i went with 2” filters. 
 

the only issue I am getting with the L-extreme is that on faint targets (well, rather faint stars in the frame), the autofocus doesn’t work properly, even with up to 20s exposures. 
while being an excellent filter, i am thinking of putting my STC duo narrowband back in the wheel, and use that instead. Both are ha-oIII filters, but the extreme is a bit more narrow. On targets with fainter stars, i’ll use that one. (Osc has limited filter use so i still have 3 slots open :) )

Apart from that, the choice for a filter wheel was to eliminate the need of opening my light path and risk getting dust in. Darks are just made with the front cap on in a dark room. 

 

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24 minutes ago, Wiu-Wiu said:

L-pro and L-extreme in the filter wheel here, with the asi 533 mc pro. 
because i wasn’t sure about vignetting, i went with 2” filters. 
 

the only issue I am getting with the L-extreme is that on faint targets (well, rather faint stars in the frame), the autofocus doesn’t work properly, even with up to 20s exposures. 
while being an excellent filter, i am thinking of putting my STC duo narrowband back in the wheel, and use that instead. Both are ha-oIII filters, but the extreme is a bit more narrow. On targets with fainter stars, i’ll use that one. (Osc has limited filter use so i still have 3 slots open :) )

Apart from that, the choice for a filter wheel was to eliminate the need of opening my light path and risk getting dust in. Darks are just made with the front cap on in a dark room. 

 

The idea of minimal handling was my thought on the filter wheel. 

What are your sky conditions like? I'm low bortle 4 in my garden, MW is a bright swathe across the sky. Never an issue for fait stars here. 

I'm just about to get a new scope too so would be nice to have a clean setup that I don't have to expose to any more chance of dust than I have to. 

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My back yard is SQM 19.3-19.6. Narrowband is the way to go, but the L pro does a decent job when shooting other targets. 
I’m keeping my setup intact when storing it in the shed or even moving it to a dark location. Saves me a lot of worries with dust or spacing. 

the 533 and esprit 120 combination has a quite narrow FOV, thus reducing the amount of stars in the field, and less chance of having brighter ones in there. I didn’t have that problem with the 071 on this telescope. 
 

the NB targets are usually quite large, with this setup I am aiming more towards galaxies and comets anyway, so i’m not going to use the l extreme that often.  

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