Adam J

It can be about three different things, colimation would have to be very far out and you would not expect it to effect all four at the same time. So this is more likely twisted spider vanes. Adam

Better to go for a 450d as you get live view function. The evoguide is not required there are cheaper optiions like the Orion 50mm guide scope.

The OVL is known to work on the ED72, so I would go for the OVL. Adam

Well that just makes me glad that I already own one then.

Is that filter rated to work at F2? Might explain the halos.

Sounds like they have designed a telecsope for ZWO cameras only as anything with greater back focus will be difficult to use as per this example.

So the backfocus on a rasa is only 25mm? Then how do people use a DSLR with one?

So this is another new OCS but look at the comment for ZWO today "we plan to release a mono camera later this year". Also the ASI1600mm pro is not discontinued. Adam

To be honest I would not go with a CLS CCD from Class 4 skys its too harsh and compromises colour balance. Class 4 is actually quite good by modern standards. I would even give galaxies a try with no filter especially if your local lighting is LED, although the sodium light might cause an issue I would imagin they will soon be replaced so it might not make too much sense to buy something to mitigate them in the short term. I dont use a filter for galaxy imaging from my class 5 site. For emission nebula I would pick up one of these: https://www.firstlightoptics.com/optolong-filters/optolong-l-enhance-dual-narrowband-deep-sky-imaging-filter.html I would go with 2 inch filter if it was me as that will allow you to keep using it if you ever change to a cooled OSC camera. Adam

Honestly the reason I went with the ASI1600mm pro and not the horizon was the ability to use 1.25 inch filter on the ASI1600mm pro, but if I was using a fast scope like the RASA I would go with the Horizon for the UK service because you will need 36mm filter in either case. So I say Horizon in this instance. Adam

I have never really gotten the appeal of these 5 position wheels. I would actually go so fars as to say I find them annoying as in some cases you are litterally talking about the same electronics with a minor firmware change yet they are massively cheaper. Or looking at it the other way, whats to justify the price hike for a bigger wheel beyond a tiny bit of extra machining. I cant imagine ever wanting anything less than a 8-position wheel for 31mm / 1.25 inch filters at anyrate but at the same time resent the price difference. Adam

I see amp glow and this chip is known for uneven cooling producing patterns in the background. So I would say its just bacause your darks are not working correctly. Adam

You are forgiven.

It would depend on your focal length.

Lol. But I guess depending on your point of view another word for pedantic is precise. 🙂 It's the scientist in me.

Daws limit applies for everything not just point sources. On nebula for example as you decrease the image scale below the Daws limit the image will look increasingly as if you have applied a Gaussian blur to it. To a certain point that will look fine but beyond that it breaks down and in no case will you actually resolve more detail irrespective of aspherics In terms of I would say that some sharpening algorithms work better to the eye if oversampled but that does not mean you have more detail it just means that sharpening is giving the impression of more detail but those are artifacts not real detail. Damian peach is using a ASI290 on a 14 inch edge HD, he is at 50% of the Daws limit but he may bin. Looking at his images at full size fantastic though they are I would say he is not resolving details down to pixel level. It's not that you are getting less signal to noise at finer image scale it's that you have insufficient aperture per arcsecond. A larger aperture scope like a RASA is therefore ideal for the asi183 as it has lots of aperture per arcsecond. As for

Gain 76 Offset 50

Yes thats doping. So a typically rare earth nanoparticles suspended in the gaps between the polycrystaline matrix of the glass but not chemically part of the glass itself, hence if you padantic like me then Lanthanum is not a type of glass. Some Lasers are made like that, hence things like Nd-Glass lasers where by the Neodymium is the active lasing element. But you can also sputter deposit it onto the surface such as you would an AR coating and acheive the same effect. Adam

The issue I always have with these is that you dont need to level a pier top to polar align and so you introduce a vibration source in making the leveling device using threaded rods.

Where on earth are you getting that from?

I suggest that you have a longer read. The daws limit is the limit to the ability of the scope to resolve distinct points of light from one another in terms of resolution. So if you have a scope with a daws limit of 2 arcsecond per pixel as you would with a 60mm aperture then selecting a small pixel camera like a ASI183mm pro will result in a image scale of 1.4 arcseconds per pixel at 360mm focal length. Hence the pixels are too small and dont actually resolve detail smaller then 2 arcseconds irrespective of the fact that your are sampling at 1.4 arcseconds. Try it, it will tell you its fine when its actually quite sub optimal as your exchanging SNR for resolution...but not actually getting better resolution by using a small pixel camera. The odd thing is they have a Daws limit calculator on their web page but dont intergrate it with the CCD suitability calculator. Adam

was never a fan of that calculator as it will tell you that chosing a camera that gives a pixel scale smaller than the Daws limit is absolutly fine.

Well I guess it depends on what your interested in imaging also then

If you search backwards in this thread then you will see I made a post covering that. Maybe around AUG 2019.

Dont know about dollers but the only real contender under 1000 pounds is a IMX183 based camera. So ASI183mm pro or Altair or QHY basically take your pick. As for the higher price range, that will depend on many factors. Adam