Catanonia

Excellent, thanks gents. It was something I thought would not be a problem reducing the image size from big to small (binning) and going this direction "should" work.

Will experiment in taking my master 1xbin flat and Integer Reducing it to a 2xbin and see what happens to the subs after calibration.

If that doesn't work, will take the actual individual flats, bin them and then integrate them with their appropriate 2xbin bias and darks.

Maybe a silly question, but is the following possible / wise

• Taking a 1xbin flat frame integration and x2 software binning to create a 2xbin flat frame  (Assuming the focus and image train is the same)

Obviously best to do dedicated 2x bin flats, but lets assume you forgot to take them but have 1xbin flats from the same session

Logic tells me it should work, but I am always wrong

Thanks

Ok here is a 2min sub at bin 2x with phd rms of about 0.6

I defocused a star in the centre of the frame, tweaked the secondary until good cantered doughnut. Tried video but atmosphere made it very difficult, but when I could see it looked good. 

• Then I move star to corners and same test. Tweaked primary to get central doughnut
• Then repeated process centre, corners etc
• Then set focus to prime focus for imaging, took bright star and checked vanes ‘ spikes in centre and corners. All looked good.

3 hours ago, powerlord said:

is this 'telescope alignment evaluation image' a 'thing' ? if so - what is it ?

Sorry could not resist.

on plus side I tnig I have tweaked my own scope. Stars certainly look better.

Cracked it

22 minutes ago, vlaiv said:

Stars in corners as far as you can place them (like 50px from each side), just make sure you place them in more or less the same position in each of the corners.

3/4 is when you are imaging and you want to achieve good focus all over the frame. You then focus on single star that is about 3/4 away from the center. If your autofocus routine examines all the stars in the sub - you don't need to bother, it will find best focus position so it minimizes star sizes all over the place, but if you focus on a single star - then don't choose one in the center of the sub but rather ~ 3/4 out (or 2/3 - no need to be very precise about it).

Yes, but make sure you have doughnut centered in your frame - like dead center.

On a separate note, since you have focuser tilt to adjust as well, and above procedure does not address that - here is what I would do.

You adjust tilt of focuser as a first step prior to collimation of the rest of the scope - you'll need some sort of laser that is collimated itself - that you can put in your focuser. Procedure is simple - laser spot should hit dead center of secondary mirror and remain there as you rotate laser while in focuser (like rotating eyepiece that is placed in focuser).

If dot moves when you rotate laser - laser is not square to focuser so you need to fix that - otherwise - if it's hitting center of the secondary - you are done.

thanks, focuser tilt was the 1st thing I sorted out and pretty sure I have that boxed off.

Will play a little more tonight to see if I can refine the collimation before my imaging session.

Thanks

@vlaiv  

So getting getting

• Central hole centred is via secondary mirror adjustments
• Stars in 3/4 of corners (because I am APC) aligned is primary mirror adjustments

As a rough rule of thumb , flipping between the adjustments of secondary and primary.

46 minutes ago, Tomatobro said:

I wish I had not read this post......I have just started with a 10 inch RC.....will take a look at my stars🤨

It is worth the effort. A steep learning slope for me, but well worth it.

I have almost got good collimation, but as Vlaiv has shown, there is still a little way to go.

I will play a little more tonight, but being this close is good enough for me

1 hour ago, powerlord said:

asiair manual focus - just click on a star in focus mode. it will put a box around it. click the + and it will take you into the measurement screen where you can manually adjust eaf to minimise size.

Ah, thanxs, that I did not know

4 minutes ago, vlaiv said:

Loads of stuff

 

Mind blown, will have to re-read this many times, but I think I get your reasoning. Watch this space and thanxs

3 hours ago, vlaiv said:

That collimation needs a bit of tweaking to get it fully right.

and more

At times Vlaiv I hate and love you   Still a little improvement to be had.

• Yes, forgot, bin in software to increase SNR
• Not sure if I can focus on a single star with ASI Air Pro and ASI EAF as it auto detects a star.
• Will experiment a little more with the collimation. Although for Galaxy hunting, I will no doubt be cropping the centre portion of the image.
• If I add a 0.67 reducer, will I have to re-collimate (assuming a good straight / quality reducer and correct spacing) or will the native collimation hold true for the reducer as well ?

Thanks for your patience.

3 hours ago, powerlord said:

free trial available - and unlike pi trial you don't need to prove to the gestapo that you are genuine user.

stu

Trying it now, nice concept, but hard to work out. Will keep playing, but can see how easy images can be taken out of it.

Ok played a little more, StarTools is quite clever. My quick playing and it seems star tools gives an unnatural feel to the images with too much sharpening, local shadow enhancements and a reliance a lot on wavelets. Perhaps it is just me and my obvious lack of skill in Startools. I will keep it downloaded and play more with it on other images

In PixInsight, a little Wavelet action without much testing gave this, I feel a more natural image.

8 minutes ago, powerlord said:

I don't know how you process, but I've found startools gets me better results with galaxies than anything else I've tried. might be worth a go as I'm sure there must be a lot more data in that massive frame to eek out.

stu

Thanks Stu, much appreciated. Not sure on the collimation airy either as was the 1st time for me too. Will do some more reading, but the collimation was a marked improvement upon the 1st attempt.

Will check Startools a I only use PixInsight at the moment

Firstly I would like to thank all that helped me with the collimation of the 10inch RC. Especially @vlaiv who is a fountain of knowledge.

The scope arrived from TS Optics and as expected, it needed collimation. The focuser tube was out (surprising) and the mirrors needed collimation too (not surprising as happens in shipping)

My learning process was very steep as never owned a RC before. The OCAL electronic collimator is good and helps get the focuser / primary and secondary close in the warmth of your house. But it only got it close and not perfect.

My first light was good, but it was obviously my stars were not good and collimation was indeed out.

Last night, I taught myself (with help from others, thanks) the defacto bright star collimation and eventually nailed it..... Yippeeee !!!!

So below is my 2nd light of M51 that I took last night. I am on the limit of CCD suitability with the scope and camera, but my guiding was very good averaging 0.5 in PHD2 so I risked 1x bin subs mainly to see any imperfections in collimation.

Amazing that M51 fills 1/2 of the sub frame at 1:1 zoom.

Click the M51 pic and zoom in  It is HUGE !!!!

• 138x 2min subs at 1x bin (about 4.5 hours)
• TS Optics (GSO) 10 inch RC open truss
• ZWO 2600 MC Pro and no filters
• EQ8-R Mount
• WO66 guide with ZWO 120mm guide camera  (PHD2 averaged 0.5)
• ZWO ASI Air Pro
• Bortle 6 skies and 83% moon

2000mm is probably too much for my Bortle 6 skies / imaging resolving power. Next is to experiment with the 0.67 reducer as I think this will be the default for me.

So my initial impressions are

• Awesome service from TS Germany as always
• Get the reducer from TS to give you options for 2000mm @F8 or 1340mm @ F5.3 - I have only tried at native F8 so far.
• It has a very flat field out of the box when properly collimated. 
• Open truss picks up dust easily, get a hand blower if this concerns you.
• Scope needed collimation on all 3 of focuser, primary and secondary so be ready for that
• It is heavy, 15.3 KG for the scope, about 22kg with all the kit on. It is fun lifting it up to the EQ8-R for mounting. I would say a EQ8 class of mount is a must as a EQ6 class would really struggle.
• I didn't need the cloth shroud as the baffle tube to the primary works well. Even last night under a 83% moon and I had no issues with light leaks.
• Taking flats is an issue, I used the teeshirt during the day method with the cloth shroud to stop the teeshirt falling into the open truss. I still need to refine this more.
• There is no ZWO EAF bracket for the GSO focuser, I had to 3d print a shim.
• Putting the primary mirror cover in / out is a PITA, ensure you have the secondary one on 1st to avoid scratches
• Due to extreme 2000mm, I hardly got any Elon trails (depends on target) - Nice
• It is impressive to see M51 fill half the image sub and not have to zoom in massive amounts 
• It is great to be galaxy imaging again as my Rasa8 is just not cut out for this type of work. RC for summer / RASA for winter

Again thanks all that helped with my new scope and the stupid questions I had

I have sorted out the collimation on the 2nd night by using the old fashioned star test.

Managed to re-do M51 last night with about 4 hours of data.

Will repost soon. Here is a single 2min 1xbin sub

Thanks all. 2min subs coming in at F8 2000mm and phd around 0.5. Looking good

Focused out more and adjusted secondary. Looks MUCH better now @vlaiv

Does this defocused star test look good ?

trying to refine the collimation on my f8 2000mm credit scope

thanks for any help you can offer

I wanted a scope for galaxy work to complement my Rasa8 for widefield.

Being me, I don't do things by half and recently took delivery of a TS 10inch Carbon Open Truss RC scope (GSO clone)

I have spent a good 1/2 day learning how to collimate it with an Ocal electronic collimator and looks like I got it fairly close. Although the M51 image below will show my collimation is slightly off.

It is a very heavy beast to lift and mount on to my EQ8-R mount (about 22kg all in with accessories bolted to it)

The equipment is 

• TS Optics 10inch RC at F8 2000mm
• EQ8-R mount
• ZWO 2600MC Pro - no filters
• WO66 guide scope with 120mm ZWO guide camera
• ZWO EAF
• ASI Air Pro

So first light target was my favorite galaxy, M51 Whirlpool and I got 150 2minute subs at binx2.

No flats used yet as I have to figure out how to do this, so PI DBE was used.

Guiding with the 388mm WO66 was around 0.5 - 0.7 in PHD so pretty good.

Below is a very quick process of 90 of the best subs along with one of the single 2min x2 bin subs. The image scale is 1:1

I can get better than this if I sort out the collimation a little more on a star test. It looked ok as a quick star test, but the subs definitely show it is still off a little.

So great to be back to imaging galaxies.

1st light.

120s at 2xbin with zwo 2600mc pro. Jpg raw from asi air pro

Native F8 at 2000mm 

yet to play with reducer to get it to F5.3

collimation off a little, but pretty impressive

5 minutes ago, JeremyS said:

Looks fantastic. Forecast looks promising for tonight 🤞🏻
Do you have a cover for the scope or set up each night?

Mount is permanently outside under a cover, scope get put on and off for each session.

Takes about 5 mins to mount and connect cables.

Oh wow she is big !!!!

My new 10inch RC Open Truss sat on my EQ8-R

Did I say it was HUGE !!!   BRING ON THE GALAXIES

All set up ready to find focus points and check collimation tonight hopefully.

Has ASI Air Pro, EAF and an old WO66 as a guide scope.

ZWO 2600 MC Pro camera attached

12 hours ago, powerlord said:

Let us know how u get on.

Will do once I get my guide rings delivered. Going to use either an old ED80 or old WO66 as a guide camera

12 hours ago, Clarkey said:

Sorry. Maybe came out a bit wrong. It wasn't meant to be patronizing.

No problems, didn't come across like that

47 minutes ago, Clarkey said:

I would still suggest a star test as this is the last step. However, carefully I have aligned everything visually when I do a star test it is always slightly off.  The good news is that once set I very rarely need to adjust it. Also, once you put the extension rings back onto the scope and star test you might find there is a small amount of tilt (between the mirror and the focuser). Tests up to now assume everything is aligned - which if you are lucky it will be. If you put the cheshire back on with all of the extension rings in place - after doing the star test and getting it 'perfect' - you might find the secondary slightly off centre for this reason.

Yup true test is a star test with image train in place

@powerlord I think I have it done.

I have enlarged the thickness of the lines to make it easier to see.