Odd offset star reflection.

[gaz81]

Can anyone advise what is causing this?

Camera is a Canon 100D with Baader mod, attached to a StellaMira filed flattener with a 2inch SkyWatcher UHC filter screwed on the end of the flatener.... then attached to a Skywatcher 72ED.

Seems to happen on the brighter stars, can only assume its the filter.

Shows more with 20 x 200s exposures stacked. 

This is the filter:

https://www.amazon.co.uk/Sky-Watcher-UHC-Ultra-Contrast-Filter/dp/B00AWD3YC6

 

Autosave.tif

Edited October 17, 2020 by gaz81

[Seelive]

I get the same effect on bright stars with my IDAS D2 filter away from the centre of the FOV when using 'fast' lenses (f2.8).  It is certainly down to the filter, identical images without the filter show no such aberrations. 

[almcl]

Don't be too quick to blame the filters. 

I get a similar effect on bright stars with no filter in the train.  Beginning to think it may be an artefact of the DSLR matrix/Baader Filter &c  (single cropped sub from 1st light with my SW190MN):

[gaz81]

Hmmmm

Interesting. 
 

At least it’s not just me then 🙂

guess will need to learn out to deal with it in PhotoShop. 

[Seelive]

Don't be too quick to blame the filters. 

Since I've taken identical images of the same star field using exactly the same equipment and exposure etc with and without the filter, I think I can say it's the filter.

[almcl]

Sorry if it wasn't clear, I was referring to the OP's question, not your response.  His issue may or may not be caused by the filter.  Mine isn't.  It might be him worth checking.

[Seelive]

@almclApologies if my response seemed in any way antagonistic, it certainly wasn't intended that way. I suppose the question could easily be answered by comparing images taken with and without the filter.

[almcl]

Just now, Seelive said:

 Apologies..

the question could easily be answered by comparing images taken with and without the filter.

No apology needed, I was trying to clarify and, yes, absolutely, a test image with and without filters should help clear things up.

[gaz81]

Next time its clear.... will give it a try 🙂