Stars look like Saturn

[ampleamp]

Attached is a roughly stretched frames from a new setup - I was using a 6" refractor through a reducer onto an Atik 383L. Please ignore framing etc as I was just playing between clouds. All of the L frames taken that night had some form of similarily angled reflection through the brighter stars of M45.

There was a bit of stray light that night as my neighbours had their security light on and off but this was at 90 degrees to M45 and the light was certainly off later on. Whilst the reflections spikes (?) seemed to be a fairly consistent feature of all the L frames they were much less so in the RGB. There doesn't appear to be any problem in the filter wheel etc

Any suggestions as to the possible cause are more than welcome,

thanks,

Alistair

[Steve Ward]

If you save the image as a PNG file it will show in your post and save folks having to mess about downloading unknown files ... 

[ampleamp]

Image type changed 

[cosmojaydee]

A refractor should not produce any kind of spikes I would have thought , A reflector would and these odd spikes could be caused by many things, Pinched mirror, clothes lines, trees. stray light , bent /twisted spider veins, you will have to try and eliminate them one by one 

[D4N]

Looks a lot like a sub I had with my bahnitov mask still on.

Definitely something messing up your light path though, hope you can find it.

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[ampleamp]

thanks guys, definitely no external block like lines or trees etc and definitely a refractor , not 100% certain it wasn't the neighbour's lights but they haven't given me any image problems before with the same scope but a different FW and camera. It is the first time i have used the reducer so I am wondering if i might have some reflections in here (???) as I am 99% sure i didn't leave the bahtinov mask on although it has been known. One option would be to try another bright object and see how it all looks. 

By way of comparison, here is a single stretched R frame.

Any other suggestions?

[D4N]

Maybe a reflection between the reducer and filter, do you have any images without any filter in place?

TSED70Q, iOptron Smart EQ pro, ASI-120MM, Finepix S5 pro.

[ollypenrice]

Very very odd, Alistair. I've never seen anything like this before. A further curiosity is that the lines are strangely orientated (though this should be a clue.) Look at how the angle of the line through the star gradually changes from the top of the image, where they are close to horizontal, to the bottom where they are at something like 45 degrees. Near the bottom you need to look carefully to see this.

I've never seen reflections look like this. You get blobs of light from internal reflections and possibly lighthouse beam-like flares from stars out of shot. 

The fact is that obstructions in the lightpath are the things which generate artefacts out of stars like this. I'm wondering if you might have had a temporary intruder like a spider's web. If this were curved in the plane of the objective it might produce the change in spike orientation noted above. I'm not really sure about this, but the point of curved spider vanes is that each part of the curve produces a tiny artefact in a different orientation to that produced by the next point along the vane.

I can't see this being reflection. For me it is most likely to have been created by obstruction - but I could be quite wrong as I hasten to stress.

Olly

[ampleamp]

It appears Olly that you may well be on the right lines, although I can not see any physical obstructions I have read a thread on CN where some spikes were observed on images using the same scope and there was some discussion re the merits of baffles, numbers and alignment. Maybe???

I have been in discussion with the retailer and in order to dismiss the reducer as a cause, I am going to try the EFW2/383 without the reducer and then try with the reducer on an SX/694 combination since I was previously happy with these results. The 383 chip is larger than the 694 and this may or may not be exaggerating something here.. All questions that hopefully will be answered when we get another clear night and I am not working.

[Interested]

Just to add to your list of causes:

Is everything in the optical chain attached squarely?

It does look a little like some subs I had recently, but that was caused by excessive moisture on the objective.

[ampleamp]

Well to my mind the reducer is in the clear and it might well be something to do with the scope itself, but that is just my opinion. I am now speaking to Martin from FLO, where i originally purchased the scope, and frames taken at his request both using the reducer and without show that there are still these spikes no matter what combination I try. He is sending the frames on to be assessed. I haven't had the time to retry the SX/H694 combination again but will do so when I can. Since FLO are now looking at this I am a little reluctant to comment further until we know something a bit more concrete.

[ampleamp]

Hi Pete,

everything is threaded all the way through so hopefully it is square, or at least close enough it won't make a great deal of difference for the purposes of finding out what the cause might be. It has been very damp here lately but as far as I can see the optics are as clean as they could be.

thanks,