NEW StellaMira 90mm ED Triplet Refractor

[SAW]

13 minutes ago, Gary Clayton said:

Hopefully this guide should help

Would that cause the stars to look like crosses if it's too close ?

[Gary Clayton]

1 minute ago, SAW said:

Thanks all. I'll check a single sub.

if you post a single sub, we can check it out in ASTAP.

[SAW]

Ok will do when I get home. 

[Gary Clayton]

9 minutes ago, SAW said:

Would that cause the stars to look like crosses if it's too close ?

If your to close to the reducer you get radial shaped stars pointing to the centre of the image as per the top image and cross shaped/diagonal stars if your to far away from your reducer as per the lower image, so in your case you seem to be to far away from your reducer but also have some camera/focuser tilt.

Edited June 24, 2023 by Gary Clayton

[SAW]

I loaded this frame into astap.

Light_Cygnus_300.0s_Bin1_H_20230624-012407_0031_a_REF.xisf

[Gary Clayton]

10 minutes ago, SAW said:

I loaded this frame into astap.

Light_Cygnus_300.0s_Bin1_H_20230624-012407_0031_a_REF.xisf 49.77 MB · 0 downloads

This quite clearly shows both your tilt (32%) and your Off-axis aberration (back focus error) as being high, try to get this in the 0.20 mark, I would start on the tilt first by shooting a starfield that has no nebula or clusters in it at around 30 second mark.

[Gary Clayton]

With a lot of fiddling I managed to get mine down to this from around what you have

[SAW]

I have some tilt shims which side do I need to put the raised part on ? How much should I reduce my spacing each time to notice any changes ?

Edited June 24, 2023 by SAW

[Gary Clayton]

5 minutes ago, SAW said:

I have some tilt shims which side do I need to put the raised part on ? How much should I reduce my spacing each time to notice any changes ?

It's impossible for me to say as I don't have access to your rig, it's going to be trial and error on your part. Does you camera have a tilt adapter ?, if so your need to work out which side is which as well as it's top and bottom, if your using a ZWO camera my understanding is that the bump in the camera's body is the top, have a look at these videos to get you started.  https://www.asgastronomy.com/collimation-tilt-and-backfocus/

[SAW]

Just now, Gary Clayton said:

It's impossible for me to say as I don't have access to your rig, it's going to be trial and error on your part. Does you camera have a tilt adapter ?, if so your need to work out which side is which as well as it's top and bottom, if your using a ZWO camera my understanding is that the bump in the camera's body is the top, have a look at these videos to get you started.  https://www.asgastronomy.com/collimation-tilt-and-backfocus/

I don't have the tilt plate connected the camera is bolted directly to the filter wheel.

[Gary Clayton]

3 minutes ago, SAW said:

I don't have the tilt plate connected the camera is bolted directly to the filter wheel.

In that case try getting the back focus correct first, other things to check are your focuser tube and camera rotator make sure there both nice and tight with no play or movement at all.

[SAW]

I've removed 1.6mm of spacing i'll give that a try and compare the Off-axis aberration before I tackle the tilt.

[SAW]

This is what I am getting now with the 1.6mm of spacing removed. Off-axis aberration has dropped quite a bit but looks like I still need to be a bit closer, tilt is still way off !

[Gary Clayton]

Single unprocessed 5 minute sub on M13 using an APS-C sensor, no calibration frames or crop to test out the new SM 1:1 field flattener, I adjusted it to 23mm on the scale for my setup, it will need minor tweak's when time allows.

[Anthonyexmouth]

I picked up my rotator the other day. Should make things easier now. Shame it wasn't a standard feature. Turned out an expensive ride up to FLO, ended up buying an Askar duo filter and seems a boat load of clouds too. 

 

[Gary Clayton]

I managed to get an hour on M13 last night, no calibration frames as I was tweaking my rig's setup for the darker night's to come.

[Anthonyexmouth]

OK, has anyone here with an SM90 or maybe someone a @FLO done the calcs to work out what the step size is for the focuser paired with the ZWO eaf? I want to input it in NINA for the image Abberation tool. 

[Gary Clayton]

I managed 2 hours last night on NGC6914, imaged though the twilight here in the UK and processed in the HOO palette 

StellaMira 90 with 1:1 flattener
Antlia golden dual band 5nm filter
Altair Astro Hypercam 26C Camera
Ioptron CEM40G equatorial mount

[Gary Clayton]

23 hours ago, Anthonyexmouth said:

OK, has anyone here with an SM90 or maybe someone a @FLO done the calcs to work out what the step size is for the focuser paired with the ZWO eaf? I want to input it in NINA for the image Abberation tool. 

Well I did a while ago but my old brain can't remember, I will check next time I boot up my image acquisition pc. In the mean time check out this great video for setting this up: 

 

Edited July 4, 2023 by Gary Clayton

[Anthonyexmouth]

1 minute ago, Gary Clayton said:

Well I did a while ago but my old brain can't remember, I will check next time I boot up my image acquisition pc.

Thanks. 

[Anthonyexmouth]

9 minutes ago, Gary Clayton said:

I managed 2 hours last night on NGC6914, imaged though the twilight here in the UK and processed in the HOO palette 

StellaMira 90 with 1:1 flattener
Antlia golden dual band 5nm filter
Altair Astro Hypercam 26C Camera
Ioptron CEM40G equatorial mount

Don't you miss out on a lot of the reflection nebula when using a dual band filter on this target? 

[Gary Clayton]

Just now, Anthonyexmouth said:

Don't you miss out on a lot of the reflection nebula when using a dual band filter on this target? 

Yep but any duo-duel band filter is bound too lose some, that said there is some blue in there which I could have pushed harder.

[Anthonyexmouth]

5 minutes ago, Gary Clayton said:

Well I did a while ago but my old brain can't remember, I will check next time I boot up my image acquisition pc. In the mean time check out this great video for setting this up: 

 

Autofocus is fine now I've switched back to using the default Nina autofocus and not Hocus Focus. I just wanted to get the focuser distance movement per step for the image inspector to adjust my tilt. I don't think it's super critical but with the correct number I think it give you an accurate adjustment figure. 

 

[Anthonyexmouth]

Just now, Gary Clayton said:

Yep but any duo-duel band filter is bound too lose some, that said there is some blue in there which I could have pushed harder.

Ah ok, I was under the impression that reflection nebula were more of a broadband target and a dualband blocks a lot of it completely. Only had a dual narrowband filter less that a week so I might be talking out of my....... 

[Gary Clayton]

Just now, Anthonyexmouth said:

Autofocus is fine now I've switched back to using the default Nina autofocus and not Hocus Focus. I just wanted to get the focuser distance movement per step for the image inspector to adjust my tilt. I don't think it's super critical but with the correct number I think it give you an accurate adjustment figure. 

 

Its odd that your having issues with Hocus Focus as I am still using it (latest update) with no issues, how dark was it when you tried?, as that's the only time I have had it fail so I wait until after midnight.