Filter draws vs wheels & stacking filters??

[Gastraea (John)]

Hi all
I believe I will be coming into some money soon and was planning on purchasing the much vaunted ASI2600MM Pro.

I currently have a optilong l-enchance 2" filter that I'm using with an unmodded DSLR.

I was hoping to slowly build up a high quality 2" filter set of LRGB plus three narrowband filters over time. This is due to wanting to "invest" in 2" and probably not having enough to pay for the 7 position filter wheel and 36mm filters than get packaged as an option with the ASI2600MM Pro.

Anyway to cut to the chase I was looking to buy some cheaper 2" LRGB filters probably from ZWO and use a filter draw.
My scope is a WO GT-81 and the optilong filter is screwed into the flatterner.

So what are the issues with stacking filters like this? I'm expecting some reduction in sensitivity but is it AP suicide?

Also I'm expecting filter drawers are a PITA but if the exposures with one filter are 2+ hours then changing them out 2-3 time over the night doesn't seem too bad.

So any comments suggestions are welcome. Is it worth stretching to invest in 2" filters??

My fallback option is to buy the camera initially and then save up for the filter wheel. Bundling doesn't save too much.

[sunslayr (David)]

Stacking filters is pretty pointless especially narrowband as they would cancel each other out. Any reason you want 2" filters? Your GT-81 is an F4.7 scope with a reducer so even with 36mm filters you would not vignette. Also if you wanted A high quality filter set (Astrodon??) 2" would be very expensive. If I were you and still wanted 2" I would get the 7x2" filter wheel and a set of Antlia LRGB filters at first and then later buy 5nm Ha and 3nm Sii+Oiii filters. I think they are a step above Zwo in quality and you have the benefit of a tighter bandpass for light polluted sky.

[Kuz]

Hi John.
I say go the filter wheel fully sealed no dust don't have to worry about finger prints on filters during change over. And later down the track attach a auto focus. And sit back a relax.

[Gastraea (John)]

Thanks for your comments/suggestion guys. I'll wait to see how much money I can scrap together and make a decision

[AdamJL]

imagine your first filter is Ha.
That means EVERYTHING, except the specific band pass of Ha +/- the sensitivity of the filter gets reflected back out of the scope, and only Ha gets in.
Imagine your second filter is OIII. Not only will that not get any OIII signal because the Ha filter stopped any OIII coming through, but now it blocks Ha and tries to send it back through the scope.
Your SII filter at the back? It's asking what the heck is going on, and why is it so dark.

Net result? Black picture.

As for 2", well that's great, but only if you ever see yourself getting a full frame camera and a scope with a big image circle. If you get neither, then the 2" will provide little benefit.

[Sunfish (Ray)]

Yep . Filter wheel. Even manual at first . You don’t want to drop a very expensive filter. You could start with just oiii and ha.

You can also have a night with ha and then another night with oiii .etc.

[Gastraea (John)]

Right so I didn't explain very well what I meant by stacking filters.

This is the way I see it. Currently I have an optilong L-enchance which has three narrow passbands. With the current DSLR it has an IR cut filter and then it has the RGB filters over different pixels in the bayer array. From a certain view point that is stacking three optical filters.

What I was looking to do was use the L-enchance to get the light pollution rejection and then the RGB filters, used one at a time, to isolate the three passbands individually and make up colour for the ASI2600MM

Anyway thanks all for your help. My main goal is to have something to play with and stagger the cost. My push to go for 2" filters is that who knows what the replacement for the ASI2600 will be. Full frame sensors may become cheap in the future.

[ChrisV (Chris)]

If you are going mono go with individual filters -rgb and narrowband. The l-enhance and others like it are really for colour not mono cameras - allow you to split h-alpha and o3 on the red v blue/green Bayer matrixes. You won't be able to split them on a mono cameras

You only need 36mm filter with an aps-c, not the larger 2" filters

It doesn't make sense to l-enhance then RGB on a mono. You'll get transmission loss through 2 filters. Also the l-enhance is not as good as individual narrowband filters


Cheers Chris

[jahnpahwa (JP)]

Originally Posted by Gastraea

Right so I didn't explain very well what I meant by stacking filters.

This is the way I see it. Currently I have an optilong L-enchance which has three narrow passbands. With the current DSLR it has an IR cut filter and then it has the RGB filters over different pixels in the bayer array. From a certain view point that is stacking three optical filters.

What I was looking to do was use the L-enchance to get the light pollution rejection and then the RGB filters, used one at a time, to isolate the three passbands individually and make up colour for the ASI2600MM

Anyway thanks all for your help. My main goal is to have something to play with and stagger the cost. My push to go for 2" filters is that who knows what the replacement for the ASI2600 will be. Full frame sensors may become cheap in the future.

Take a look at the RGB transmission graphs, you'll see the wavelengths of common light pollutants fall in the dips where the r, g and b overlap. In short, don't worry about stacking a light pollution filter onto broadband colour filters, they have you covered.

[Gastraea (John)]

Thanks all
Pending money I thing the decision I'll go for is 36mm ZWO LRGB filters with the 7 position filter wheel. The narrowband ZWO filters are out of stock at the moment but it will give me time to figure out which brand & save up more.

I should have enough to play with for a while.

Does anyone really image with Hydrogen Beta?

[Gastraea (John)]

Postscript/Update

I just placed and order for an ASI2600 with 36mm 7 position wheel and LRGB HSO filters.

So time to list the L-enhance filter in the classified LOL

[rustigsmed (Russell)]

Originally Posted by Gastraea

Thanks all
Pending money I thing the decision I'll go for is 36mm ZWO LRGB filters with the 7 position filter wheel. The narrowband ZWO filters are out of stock at the moment but it will give me time to figure out which brand & save up more.

I should have enough to play with for a while.

Does anyone really image with Hydrogen Beta?

Originally Posted by Gastraea

Postscript/Update

I just placed and order for an ASI2600 with 36mm 7 position wheel and LRGB HSO filters.

So time to list the L-enhance filter in the classified LOL

nice decision - i rocked a filter draw for quite some time with 2" filters. even used them for RGB planetary imaging - got to be quick
yes it is fine to use can even help with a more rigid linear imaging train with no sag or lean - but eventually you will want a filter wheel.

H-beta isn't used that often, I wouldn't worry about it unless you had a particular interest in imaging Hbeta. Often people will blend in some Ha into the blue (15-20%) in an HaRGB image to simulate H beta (from a colour perspective as Hbeta is blue).

cheers

[xelasnave]

Good on you.
My advice would be what you have done.
I have a seven wheel job with a zwo 1600 and it is great.
But with my RASA 11 you need filters drawers..seven of them ...already just trying to organise them in a box is a pain..I bought a ZWO 2600 mono and got tired waiting for the filters and got a zwo osc 2600 but it hasn't stopped raining or cloudy so haven't used a thing