Clarkey

Looking at the image above suggests it is more than just distance from the sensor - possibly some tilt as well. The star shapes are certainly not consistent with purely a back-focus issue. If it is was purely distance  all of the stars would be pointing away from centre or around the centre - but this is a mixture.

From my experience of the RC8 I found collimating the secondary worked well with the TS collimator (even though it is the world's most expensive LED light with a hole in). Following this I use a star test to get the primary aligned. Whether this is the 'right' way is another question but it works for me.

I have tried some other methods including the laser version which completely ruined my relatively good collimation. Once right I think they are excellent imaging scopes.

I have used a similar system to Budgie1 above without a problem. (The asi1600 was temperamental with the hub but the cable was ok). You can get 12v powered hubs which make it easy to use a standard astro supply.

I have now converted to a Mele Quieter 2 mini PC at the mount for convenience which is just easier for me.

I have not used the 2" version but the 7/8 position wheel I have has been absolutely fine. I am not aware of any specific issues with the larger wheel but I am guessing most of the control is pretty the same. I do multi filter imaging and flats without a problem.

I would suggest if you are struggling to balance the scope the axis are too stiff. I would recommend a strip down and regrease to loosen the whole thing. My HEQ5 was stiff (but not that bad) but is now very smooth and easier to balance. I would also add that if the axis is that stiff the guiding will undoubtedly be affected also.

20 hours ago, Dave2292 said:

caution previous NPE is applied

You should be able to go into the handset and reset the NPE value to 0 in the settings menu.

6 minutes ago, ONIKKINEN said:

I dont trust bahtinov masks, even for DSO imaging. My star sizes decreased noticeably after switching to statistics (HFR) and visual based focusing.

I am happy to use a bahtinov mask if necessary, but statistical measurement is easier as I am always connected to a screen. I generally get the same result either way.

I'm glad I'm not the only one.....😂😂

A couple of things come to mind. Firstly, I assume the sensor distance from the camera front to the sensor is the same for the ASI and QHY? In theory the focus point with the same kit should be at the same place so the 20mm difference does not make sense. Secondly the star shapes seem to be getting worse as the distance increases (although I am looking on a small screen). Are you sure it does not need to be closer?

Probably not much help, but it is all I can think of.

I struggle to track the moon so I am suitably impressed. That is truly excellent.

I agree that the dithering frequency needs to increase. Every 10 frames is only 6 times in the hour which will not be enough to 'staitstically' remove the noise. You could adjust the clipping algorithm but you will probably start loosing detail.

7 minutes ago, Simon Pepper said:

wife filed scope

Keep her away from your scope🤣

Looking at the image I would say there are two things that will improve your guiding.

Firstly a bigger and better mounted guidescope to ensure no flex. Secondly adjust the mount to get the RMS down.

26 minutes ago, AstroMuni said:

Interesting. The Evostar line up shown under their US website are heavier

They do quote 'with accessories' which I assume is finder, diagonal and eyepiece plus tube rings and dovetail.

13 minutes ago, AstroMuni said:

That sounds very light -are you sure? I thought the 80ED itself was around 4kg

Skywatcher Website quotes 5.1kg for the OTA. Add a bit for the tube rings gives about 5.5kg. The ED80 is given as 2.5kg.

Sky-Watcher | Sky-Watcher Global Website (skywatcher.com)

With regards to the star shapes this does look like a guiding issue. The RMS you are getting is not very good for an HEQ5 - it should be well under 1. The Rowan upgrade will help, specifically if there is significant backlash, but I do find my HEQ5 does require regular 'tweeking' of the worm drive to keep the guiding to its optimal. The end float on the bearings is also critical. I think you need to get this better before going to OAG as you may end up with the same problem.

As for the black mark - this definitely looks like dust/dirt close to the sensor - probably on the sensor glass.

2 hours ago, AstroMuni said:

Worth bearing in mind that the 120ED is quite heavy and HEQ5 Pro may not be suited if you want to get into AP at a later point in time. Just a HEADS UP

It is towards the top end but I think it should be ok. The ED120 is about 5.5kg and the HEQ5 is probably ok up to 10kg or so. Providing the other kit is not too excessive I don't see it struggling.

Having said that I would say a shorter FL may be a better starting choice of AP. Maybe start with your initial choice and consider buying a small refractor at a later date for imaging.

5 hours ago, Iem1 said:

am also unsure of the difference between mounted/unmounted filters? (Manually inserted/changed v's electronic?)

Unmounted filters are just glass. You need a frame to hold them in the EFW. Mounted are screw fitting with an outer metal ring.

5 hours ago, Iem1 said:

Which if I'm not mistaken would be inserted into my field flattener as to block UV/IR before it hits the NB filters?

You won't need to use a uv/if filter with the other filters. You only need this for some OSC cameras and for luminance data. This is basically what the standard ZWO luminance filter is.

5 hours ago, Iem1 said:

Or is the LRGB equally as important for producing inages

You can get away without LRGB but most people use these for true star colours. With NB you cannot get accurate stars.

48 minutes ago, Simon Pepper said:

. If you get Sii and Oiii at a later date you will wish you got the 7/8 position EFW as it’s a pain opening it up and swapping out RGB

This is very true, especially if you are using 31mm unmounted filters. If your budget won't stretch to the 8 position wheel, the 1.25 mounted filters would be more user friendly to swap. However, the 31mm do allow slightly larger sensors.

FWIW I have the 1600mm pro and I have been really pleased with it. Flats are easy and amp glow is easily calibrated out. It is 'old tech' now but still very capable. I have recently purchased a Rising Cam IMX571 colour camera to complement the mono camera. (Could be an option for you?). I'll be using the 1600 for luminance data and the 571 for colour on a dual rig.

Ultimately any of these choices will give you good results, but if it was me I would start with the mono route. Personally I find the processing no harder than colour and you get the option of true narrowband imaging.

FWIW I use the DSI collimation method with a REEGO collimator for the secondary mirror. RC collimation is known to be tricky and it took me a call while to get the best method for my RC8.

The ED80 is a very good starter scope for imaging. There is a small amount of CA which can be removed in processing or you can use an L3 filter to reduce it. The focuser is OK, but some people have struggled with it for AP.

8 hours ago, Budgie1 said:

This configuration won't work with your Starlight focuser so it will have to be located somewhere else in the train.  

Oops. Missed the the Starlight focuser reference. Yes you are quite right - but a screw fitting system would still be a better option.

Yes I agree. Looks like tilt to me.

I would suggest you get the rotator / adaptor and screw the flattener directly into the focuser. It is quite a long imaging train hanging on the 2" fitting. something like this:

Sky-Watcher EvoFrame Camera Rotator for Evostar 80, 100, 120, 150ED DS Pro | First Light Optics

8 hours ago, lankywolf said:

Let's assume I go for a DSLR. It must have a tiltable screen as I suffer a little bit with my back. What's the best I can get for say £500? 

I don't think you need to spend 500. You will get something like a 600D for 2-300 which would be a good starter.

You can convert Nikon cameras but I think Canon are generally easier to work with.

On 25/06/2022 at 17:45, ONIKKINEN said:

Primalucelab rings, apparently made of gold according to the price

No. Gold plated platinum encrusted with diamonds.😆

You can get a DSLR with an APS-C sensor for <£200. I don't think you would get close to this with a cooled astro camera. I agree that if you have the finances a cooled camera is certainly the way to go, but a good sized sensor which will pair well with a 135mm lens would be difficult to achieve within budget.