Any ideas what this is caused by

[alan potts]

1 hour ago, rockinrome said:

Is this a slight imperfection/crack in the glass that the eye cannot see ...??
 

Well that is sort of difficult to trace, one would hope not, can't see anything but I am having a better look later on.

Alan

[alan potts]

For everyone, just out of shot is Sadr, fairly bright, here are 25 stacked 4mins images and some actually had Sadr in them, which I cropped. Same telescope, same reducer, same camera position, only I was a few days younger.

 

Alan

[JamesF]

Is this the TSRed 279 reducer, Alan?

James

[alan potts]

13 hours ago, JamesF said:

Is this the TSRed 279 reducer, Alan?

James

Yes James the large one for 3 inch focusers, not very impressed, it is a good job I didn't buy it new.

Alan

[JamesF]

I wonder if the spacing might be out slightly then.  I have the 2" version and whilst I haven't used it yet because I didn't have the right spacers to get the correct backfocus, it does appear to vary quite a bit with the focal length of the OTA.  They give a table of backfocus distances on the web pages for each reducer, but I suspect they're only actually guidelines and that experimentation may be required to find the exact distance.  What OTA are you using?

As already suggested, I think I would be trying all the usual stuff like rotating the camera, rotating the camera and reducer, trying a different camera, even rotating the telescope if that's possible, to try to identify what is causing the problem.   Like the ASI1600 microlensing issue, it may be a specific combination of kit or something specific to the positioning of it that combines to give you a problem that you wouldn't otherwise see.

James

[alan potts]

5 hours ago, JamesF said:

I wonder if the spacing might be out slightly then.  I have the 2" version and whilst I haven't used it yet because I didn't have the right spacers to get the correct backfocus, it does appear to vary quite a bit with the focal length of the OTA.  They give a table of backfocus distances on the web pages for each reducer, but I suspect they're only actually guidelines and that experimentation may be required to find the exact distance.  What OTA are you using?

As already suggested, I think I would be trying all the usual stuff like rotating the camera, rotating the camera and reducer, trying a different camera, even rotating the telescope if that's possible, to try to identify what is causing the problem.   Like the ASI1600 microlensing issue, it may be a specific combination of kit or something specific to the positioning of it that combines to give you a problem that you wouldn't otherwise see.

James

Mine is 805mm and I sort of thought 5mm wouldn't matter too much, Dave had a look around and said there were others with problems and were being made to jump through hoops to prove it, which sound like this outfit judging by experiences I have had.

Alan

[alan potts]

Still not totally sure what caused this issue with internal flare but now it appears to have gone away, camera placed in the exact same places causes nothing. I have an odd feeling it is caused by a small piece of damage on the lens hood of the scope. I turned this round as a way of eliminating it and now have blacked it over.

Alan

[ollypenrice]

These are fairly standard problems but, alas, not ones which are easy to solve. I'd be confident that the light source is simply from the stars and almost certainly ones out of shot. I'd also put money on it being generated by the distances between internal glass surfaces, not from any damage-related defects. Since many of these distances can't be adjusted the problem is often intractable. This is why I'm very wary of generic reducers. Dedicated ones should have been tested for compatibility but generic ones, however up-market, make simply conflict with certain scopes. One of our guests, for instance, struggled with internal reflections when using a Riccardi reducer-flattener with his TEC140. TEC's own flattener, though, is a peach and actually improves colour correction. (TEC say it doesn't but it does! )

I don't get your round arcs but sometimes, like everyone else, I'll get flares from stars out of shot. The only fix I can think of is to move the scope a little towards the source of the flare (may seem counter- intuitive) and to shoot the flare-affected bit of sky from this new position. This gives me a 'patch' I can use in Photoshop layers. You don't need anything like the same depth of data for this. 

I guess it will be a matter of luck whether small changes in spacing will cure the problem but I'm afraid I wouldn't bank on it.

Olly

[alan potts]

17 minutes ago, ollypenrice said:

These are fairly standard problems but, alas, not ones which are easy to solve. I'd be confident that the light source is simply from the stars and almost certainly ones out of shot. I'd also put money on it being generated by the distances between internal glass surfaces, not from any damage-related defects. Since many of these distances can't be adjusted the problem is often intractable. This is why I'm very wary of generic reducers. Dedicated ones should have been tested for compatibility but generic ones, however up-market, make simply conflict with certain scopes. One of our guests, for instance, struggled with internal reflections when using a Riccardi reducer-flattener with his TEC140. TEC's own flattener, though, is a peach and actually improves colour correction. (TEC say it doesn't but it does! )

I don't get your round arcs but sometimes, like everyone else, I'll get flares from stars out of shot. The only fix I can think of is to move the scope a little towards the source of the flare (may seem counter- intuitive) and to shoot the flare-affected bit of sky from this new position. This gives me a 'patch' I can use in Photoshop layers. You don't need anything like the same depth of data for this. 

I guess it will be a matter of luck whether small changes in spacing will cure the problem but I'm afraid I wouldn't bank on it.

Olly

Olly,

I took it off a few times to check and put it back on, seems to have stopped now for whatever reason. I also played with the spacing but we are talking maybe .25mm, if that, I noticed the thread reducer in the Canon bayonet was very slightly proud, so I turned it, now it's not. The Riccardi is the one for mine really. but at the time it was 700e, which I thought was a bit steep, this one is priced at 345e but I got it S/H here. Your correct in what you say though.

Taken it off altogether today as I am going to try and get to grips with the Zwo 071, I am not hold my breath as I don't have much idea what I am doing, I can't use the Reducer with this camera as I don't have the spacing. There is no room for a 2 inch filter inside so I need to put it inline with a 6mm spacer I don't have.

Alan