12 or 6nm Ha / OIII /SII filters

[OJ87]

Hi everyone,

I'm planning to upgrade to cooled mono (AS I 1600mm Pro) and I want to buy the motorised ZWO filter wheel and LRGBcHa OIII and SII 1,25 filters from Astronomik. Since I'm completely new to mono camera and narrowband filters world, I have a couple of questions and I hope if you could help me:

If anyone has the same equipment as I have a fast Teleskop F4 and 1000mm focal length.

Would I face any problems with vignetting with  my telescope?

I know 6nm can show more contrast and details than 12nm, should I take all the filters with the same wave length (6nm)? i have a bortel 4/5 skies. 

Best regards, 

 

 

[Anne S]

I use 36mm with a 16mm diagonal ccd with a back focus of 17.5mm. Mostly because adding a focal reducer gave me bad vignetting with 1.25 filters. It did work with the smaller filters without. Any reducer brings the focus point closer in which causes the problem. I believe the ZWO cameras have short backfocus which may make the smaller filters possible.  FLO lists 1600 cameras in bundles with various filter sizes, it might be worth asking them. Flats will deal with any difference of illumination but it gets more difficult if the there is bad vignetting. 
 

As to the filters, 12nm filters are normally for noisier cameras such as DSLRs. CCD and CMOS cameras can use 6nm or narrower. 
 

[OJ87]

3 hours ago, Anne S said:

I use 36mm with a 16mm diagonal ccd with a back focus of 17.5mm. Mostly because adding a focal reducer gave me bad vignetting with 1.25 filters. It did work with the smaller filters without. Any reducer brings the focus point closer in which causes the problem. I believe the ZWO cameras have short backfocus which may make the smaller filters possible.  FLO lists 1600 cameras in bundles with various filter sizes, it might be worth asking them. Flats will deal with any difference of illumination but it gets more difficult if the there is bad vignetting. 
 

As to the filters, 12nm filters are normally for noisier cameras such as DSLRs. CCD and CMOS cameras can use 6nm or narrower. 
 

Thank you Anne for reply:

 In which Teleskop did you used this filters?

 I’ll use it now with my 1000mm f4 Telescope, as I said, but in future I may upgrade to SC C11 or go for smaller focal length Teleskop. Could it be a problem using those filters then?

 

[Laurin Dave]

6 hours ago, OJ87 said:

Hi everyone,

I'm planning to upgrade to cooled mono (AS I 1600mm Pro) and I want to buy the motorised ZWO filter wheel and LRGBcHa OIII and SII 1,25 filters from Astronomik. Since I'm completely new to mono camera and narrowband filters world, I have a couple of questions and I hope if you could help me:

If anyone has the same equipment as I have a fast Teleskop F4 and 1000mm focal length.

Would I face any problems with vignetting with  my telescope?

I know 6nm can show more contrast and details than 12nm, should I take all the filters with the same wave length (6nm)? i have a bortel 4/5 skies. 

Best regards, 

 

 

According to ZWO website you'll need 31mm filters at f4 as the 1.25" ones will vignette below f5..  I'd suggest you consider 36mm filters as these will be more versatile in terms of working with other manufacturers kit which tend to have greater filter to sensor distances then ZWO's kit.   Baader do both sizes (Astronomik don't seem to do 31 or 36 mm, well at least not on the FLO website)..  With narrowband narrower equals better contrast.  

Dave

[Anne S]

I'm using a 102mm F7 refractor so not particularly fast. I did have slight vignetting in the corners with this setup. Once I added a 0.79 reducer it became a problem so I bought a set of Astronomik 36mm filters after checking with Starlight Xpress, the ccd manufacturer. With the 36mm filters, I'm not aware of any issues.

As I understand it, the faster the telescope the more issue you may have. I suspect it steepens the light curve as it comes through the telescope so there's more chance of catching the edges of the filter. 
 

I used the same camera and 1.25 filters with a 6 inch  Ritchey Chretien and 0.6 reducer. The vignetting was visible then. Given that you may well fit a reducer to a SCT as the are fairly slow, I think you would have a problem. I didn't have issues when using the RC without the reducer. The SX camera is fairly long back focus, for example some of the Atik cameras have 12.5mm and I believe some of the ZWO ones have 6.5mm which will change matters substantially.

Hopefully one of the more experienced member on here will chip in. 

 

[Anne S]

2 hours ago, Laurin Dave said:

According to ZWO website you'll need 31mm filters at f4 as the 1.25" ones will vignette below f5..  I'd suggest you consider 36mm filters as these will be more versatile in terms of working with other manufacturers kit which tend to have greater filter to sensor distances then ZWO's kit.   Baader do both sizes (Astronomik don't seem to do 31 or 36 mm, well at least not on the FLO website)..  With narrowband narrower equals better contrast.  

Dave

Astronomik do do 36mm. I got some last year. 

[rickwayne]

I've heard plenty of folklore -- and repeated it myself! -- about the relationship between filter bandpass and aperture ratio, but I'd love to hear some quantitative information. I know that the angle of incidence can dramatically affect how much light passes through an interference filter. But specific nanometers and f ratios, I have not seen. My optical train is f/4.8 according to Stellarvue, I'm using 1.25" 12-nm filters on a 1" sensor with 55mm back-focus. Vignetting certainly isn't egregious -- I mean if I stretch a flat till it screams I can certainly see some, but it calibrates out easily. Heck, I've got a 183, vignetting is the LEAST of my calibration problems! 🙂 (If you don't get that joke, do a Google image search for "IMX183 amp glow"...and marvel.)

[davew]

19 minutes ago, rickwayne said:

I've heard plenty of folklore -- and repeated it myself! -- about the relationship between filter bandpass and aperture ratio, but I'd love to hear some quantitative information

http://dosandbox.astrodon.com/wp-content/uploads/2018/05/Astrodon-Narrowband-Filters_FAQ.pdf

Look about half way down the PDF on page 4.

Dave.

[rickwayne]

Thanks! This is WAY more solid info than I had. I'm still a little hungry for something deeper than "this isn't a problem with our filters because reasons", but I don't doubt their assertion -- nothing like a repeatable experiment to back one up!

Plenty good enough to guide any notional future purchases, now I'm merely curious.

And I have to go home, take the cover off my filter wheel, and peer at the physical object -- ZWO's spec sheet says 7nm, not 12, and I'm reasonably confident that's the product I have. Duh.
 

Edited February 5, 2020 by rickwayne
Mistake in earlier comment

[TareqPhoto]

I hope to see more members buying Baader filters of 3.5nm/4.5nm instead of Astronomik 6nm, i want to see how good or bad those filters as i can't afford Astrodon 36mm sizes, i already bought 1.25" sizes, but then i read all the issues about vignetting, so i think either i use cheaper 36mm filters with their own issues or accept vignetting using high quality filters, not sure what will you choose between those two.

[Anne S]

4 minutes ago, TareqPhoto said:

I hope to see more members buying Baader filters of 3.5nm/4.5nm instead of Astronomik 6nm, i want to see how good or bad those filters as i can't afford Astrodon 36mm sizes, i already bought 1.25" sizes, but then i read all the issues about vignetting, so i think either i use cheaper 36mm filters with their own issues or accept vignetting using high quality filters, not sure what will you choose between those two.

I'd love to buy some Baader ultra narrowband filters but they don't seem to stock one in 1.25" size. I don't need any bigger for my Atik 428 and I can get 9x1.25 in m'y filter wheel, so I can try a couple before selling on the older Baaders.

[TareqPhoto]

10 minutes ago, Anne S said:

I'd love to buy some Baader ultra narrowband filters but they don't seem to stock one in 1.25" size. I don't need any bigger for my Atik 428 and I can get 9x1.25 in m'y filter wheel, so I can try a couple before selling on the older Baaders.

Ok, my situation or reason is different then, but i hope to see more of that Baader Ultra Narrowbanding results, i don't mind 36mm sizes, otherwise Astronomik is an alternative, i do use Optolong, but the more i use it the more i hate it, the only reason i can keep it is if i will use lenses at F2 up to F4.

[Anne S]

45 minutes ago, TareqPhoto said:

Ok, my situation or reason is different then, but i hope to see more of that Baader Ultra Narrowbanding results, i don't mind 36mm sizes, otherwise Astronomik is an alternative, i do use Optolong, but the more i use it the more i hate it, the only reason i can keep it is if i will use lenses at F2 up to F4.

I'm using Astronomik 36mm on my  SXVR H694, 36mm ones. I'm really pleased with them. I took subs of the Ghost nebula, IC63 last night and Navi is bright but I can't see a halo around it after a rough process. My 2010 vintage Baader narrowband struggled with the bright star near the Jellyfish nebula.  I do think Baader have improved their filters since, there was a recall several years ago following halo issues. I am using a focal reducer on both scopes so that might have had something to do with it.

The scope I used last night has a 5mm extension between camera and fw as I was getting bad reflections on the camera from light sources outside the dome last year. Something to do with the reducer as I only got them when using it.  That may explain why my Astronomiks are working so well. A spacer is suggested as a workaround with some scopes when using reducers.  I must try that on my other setup. Or try turning the filters around, which is also suggested.

[TareqPhoto]

2 minutes ago, Anne S said:

I'm using Astronomik 36mm on my  SXVR H694, 36mm ones. I'm really pleased with them. I took subs of the Ghost nebula, IC63 last night and Navi is bright but I can't see a halo around it after a rough process. My 2010 vintage Baader narrowband struggled with the bright star near the Jellyfish nebula.  I do think Baader have improved their filters since, there was a recall several years ago following halo issues. I am using a focal reducer on both scopes so that might have had something to do with it.

The scope I used last night has a 5mm extension between camera and fw as I was getting bad reflections on the camera from light sources outside the dome last year. Something to do with the reducer as I only got them when using it.  That may explain why my Astronomiks are working so well. A spacer is suggested as a workaround with some scopes when using reducers.  I must try that on my other setup. Or try turning the filters around, which is also suggested.

Results are telling the trust as long there are no much deeper processing to fix filters issues, i am not looking for doing extra time to fix the halo from filters, my Astrodon Ha doesn't create any halo, even if there is it is very minimal that i can neglect, while with my Optolong Halo is always there with bright stars in many targets, even with M42 target.

[Anne S]

27 minutes ago, TareqPhoto said:

Results are telling the trust as long there are no much deeper processing to fix filters issues, i am not looking for doing extra time to fix the halo from filters, my Astrodon Ha doesn't create any halo, even if there is it is very minimal that i can neglect, while with my Optolong Halo is always there with bright stars in many targets, even with M42 target.

I'd love Astrodons but I suspect my husband wouldn't!

[TareqPhoto]

11 minutes ago, Anne S said:

I'd love Astrodons but I suspect my husband wouldn't!

And many are commenting about wives who are preventing husbands from buying more gear, lol