Adam J

i would need to see the 30s subs and guide graph to help mate.

yeah 200 seconds at 17.1c is too much Also from the stars your colimation looks out? But at least thats your target! The thing is longer subs can look better on a sub for sub basis but over a night your better off with more shorter subs by the time you stack them. 200 gain is too high for 200second subs if that length gain 50 is a better bet to not blow stars and the galaxy core out. 200 will work better with 30 second subs. Also shorter subs work better with poor tracking. Just trust that you will get something out from many many subs stacked even if the individual subs look a little rubbish. Adam

depends on the ambient temperature. Could go with 30seconds if its a warm night. I think i worked out optimal gain and exposure for you before so just go with those figures.

I would normally find 90% aggr too much but whatever works.

Its worth pointing out that theory would actually agree with that statement though.

NGC7331 looks like something worth a try, if you want a emission nebula then the Signus wall is a good bright section of the north American nebula that will fit with careful framing and a Ha filter. The crescent Nebula might work, or the propeller DWB111 fits nicely too. However the broad band galaxy target will be easier starting out. 60- 120 second luminance subs are probably a good place to start.

Could be delamination if so it will be covered by warranty but equally it might be fungus. Difficult to say. All you can do is clean it and see what happens. I recommend baader optical wonder fluid and a pure cotton bud. I have been cleaning optics for years some people say don't use cotton buds but not ever had a single issue so long as you use the correct fluid and don't push crazy hard. You could also send an image to daader directly.

Need to see a picture from the other side of the filter.

Gina ZWO discontinued all the smaller sensor cooled cameras. Your best / only option now for those sensors is QHY. Adam

If you refocus between filters then you wont see any CA on a mono camera, well unless its a really poor scope. It might cause a tiny bit of bloat on stars but it wont cause colour fringing so long as you re-focus.

I have done the same, I still have issues. I think that nothing short of a moonlight focuser will totally solve it. The other thing is that the secondary mirror can shift about if you have not got the spiders sufficiently tight (just dont distort the tube!). Adam

Similar two element design, to prevent that issue you need a three or even four element corrector.

Its probably tube droop on the focuser causing tilt and that is variable according to the direction that the scope is pointing in. The color fringes on the stars towards the edges are inherent to the Baader Field Flattner as it suffers from some degree of radial CA.

1.25 inch will work fine down to F4

No 1.25 inch mounted will do fine for F5

I think it depends on the quality of the display some are more homogeneous than others. Also how you mount it against the scope as pressure on the screen changes its brightness locally.

Unfortunately the OP is in Norway so difficult to get it out to him, costs quite a bit to post insured.

I agree, I have never had a good time getting a flat from a LCD screen. You need a proper flat panel.

Many many down sides to be honest. I think I would avoid it just because you will have a very hard time focusing is nothing else. You could get a 50pound Canon 1000D from e-bay and do vastly vastly more.

No one is going to send you a camera without taking your money first mate. I would look and see his reputation on Cloudy nights and ask to see pictures he has taken with it. Talk to the guy on the phone too perhaps. Just make sure he knows that he needs to get it to you in good time while you are still in the country. Its always a risk buying second hand but I have yet to have an issue and I have bought and sold loads of stuff. Astronomers are normally reliable types. Adam.

See my pm mate.

I am going to be putting a SW ED80 DS-Pro up for sale tonight, its got a tiny scratch about the size of a eye lash on the lens so ill be selling it at good price £190. The reality is that its performance is compleatly uneffected by this and it will vastly outperform any of the scopes you mention here in terms of colour correction and general build quality. I just thought I would point it out to you as these are normally outside the price range your considering and so it might be an option for you. Adam

I would expect the Atik 460EX mono to be significantly more sensitive than a IMX183 OSC camera. So if that is what you are used to then I am sorry to say that I doubt you will be impressed by the new camera. People seem to think CCD is dead but its just not the case. The camera has its uses but its not a direct replacement for your 460EX mono when it comes to DSO imaging in my opinion. However, I would have thought that you would see the nebula! NGC7000 is very bright perticually 'The Wall' section. Are you using the correct bayer pattern? RGGB? Are you 100% sure your imaging the correct area?? How is your light pollution are you using a filter? Can you post a image? Adam

I cant comment on US pricing but I see no issues with it.

On the basis of the above comments I think ill offer it at a reduced price compared to normal second hand, but not silly low. I will clearly disclose the scratch. Cheers all. Adam