PeterCPC

Will they not just vacuum off? I would be loathe to try to brush them as it may scratch the sensor. The windows can be replaced. I think that you won't know for sure until the sensor is cleaned and tried out.

Hello and welcome.

Hello and welcome.

23 minutes ago, iwols said:

thanks peter so once i have a dark and flats library i can use that with either scope for the same camera but i need to take seperate bias  frames for each setup i have ?

No. Other way round. You need to take flats each time you use either scope whatever the camera as it will help eliminate defects in the image train like dust. Darks and bias can be used again as long as the conditions are similar i.e temperature.

Darks and bias are specific to the camera. Flats are specific to the scope and camera.

Hello and welcome.

I don't think the C8 is ideal for DSOs (I have one) but something like a small refractor such as ED80 would be lighter, easier to guide etc.

I see what you are saying but the top graph doesn't end as such. the red line continues but I don't know what that means.

Hello and welcome.

7 minutes ago, edjrgibbs said:

I havent but it looks clear tonight so i might try with my Altair triband to see if any difference. 

Good idea. Some filters can cause bloat.

Have you tried without the filter?

Hello and welcome.

We all get nights like that. Glad you managed to fix it up ok.

4 minutes ago, FLO said:

The morning after, so back at my desk.

I see yesterday afternoon, Ian emailed you saying we would arrange for Es' to check your telescope if you wish. For your peace of mind. 

You replied that you wanted this to happen, so Ian arranged collection for Monday. All this before I replied to you here at SGL. 

I know from experience how two conversations, one here and another with a colleague via email, can confuse, so I'll bow out and leave you in Ian's capable hands 🙂 

HTH, 

Steve 

Thank you Steve.

15 hours ago, FLO said:

I understand you are already talking with my colleague, Ian. 

Kinda. 

It is after hours so I am not at my desk but my colleague, Ian, did mention this earlier today. 

He said (after looking at the images you emailed him) the pinching was only very minor, and not present at all until recently. 

I don't know if he communicated this to you, but when speaking with me, his opinion was it isn't worth your spending money trying to correct such a minor aberration. He was concerned chasing it down, to perfection, would only introduce another. 

HTH, 

Steve 

Noted but how, in good conscience, could I sell the scope on at some point without declaring this issue. If I do who would buy it? I wouldn't.

I feel that I am left with no choice but to see if it can be improved. If not then I feel it could be sold on knowing that I tried.

It's odd that the telescope was fine during it's warranty period and then develops this fault but that's just my bad luck I suppose.

I expected better from a scope at this cost.

2 hours ago, Adam J said:

Good news, I am sure they will sort it for you. 

Adam

I am not that confident as it is out of warranty.

46 minutes ago, Adam J said:

Peter, just want to politely note that although I am quite happy to give my opinion as a scientist, I don't want to be drawn into a debate with the supplier. 

Adam

No of course not. Thank you for all your help. FLO has agreed that there are pinched optics so I am trying to sort out a resolution.

@FLO Could I have your response please.

Hello and welcome.

14 minutes ago, Adam J said:

What I would say to you is that as the problem is not present at room temperature the solution may be to just to slacken each of the centring screws a tiny bit. 

I would worry about this in case I do it too much. Are they around the lens cell under the dew shield?

@Adam J Thank you for your efforts, really appreciated. I have referred the issue back to FLO to get their comments. I'm not worried about the corner stars - I am making changes to the spacing.

@Adam J

Tried again with the artificial star last night and the air was much less turbulent. Temperature was 5C.

When I transformed these from FITS to jpeg they were much brighter than they appeared on the laptop screen so the first one showing the star in focus (by Bahtinov) is not much help I think. I managed to darken the others sufficiently I hope. 1-6 were taken from in focus going out. 7-10 were taken just past focus going the other way (if that makes sense)

Astro gear is usually valued at about 70% of new prices if it's in good condition. At the end of the day it's what anyone else is prepared to pay for it.

10 hours ago, Adam J said:

I have not really experianced turbulance like that from an airtificial star normally its too close to see anything, did you let the scope cool to ambient once you got it outside.

I would also say that its still too big though better, but I am starting to see some potential notches in the outer ring.

Adam

 

Yes I let the scope cool for about an hour first. I'll try again soon.

@Adam J

I set up my artificial star outside - temp around 5C or so.

Air currents were a nightmare but these were about the best I got either side of focus. I will have a go at a real star when I get the chance.