Elongated stars in image

[Chefgage]

I processed this image of M44 the beehive cluster and noticed elongated stars in the bottom left of the image.  The top left of the image the stars appear elongated but not as bad as the bottom left (although they have a bit of a squashed look).  The stars on the top right and bottom right look pretty much ok. The stars in the central part of the image are round.  What could cause this and how could it be improved/corrected?

The equipment used was a skywatcher ed72 refractor, modified canon dslr, OVL field flattener.

Thanks for looking.

[newbie alert]

Possibly tilt, think you can run it through ccd inspector ( think there's a trail period available)

[Chefgage]

10 hours ago, newbie alert said:

Possibly tilt, think you can run it through ccd inspector ( think there's a trail period available)

Thanks I was wondering if it was tilt. But this is something I have not looked at before. I will try ccd inspector and see what it comes up with.  I have checked some of my other images and I don't seem to have that problem when using just the Samyang 135mm lens instead of the refractor. So at least it narrows it down.

[bottletopburly]

Astap has a ccd inspector built in , Startools has an algorithm to fix eggy stars which works very well 

[michael8554]

Bottom left stars are radially elongated.

All the rest are elongated TL to BR.

I'd sort that first - guiding ?

Michael

 

[gduffett]

 

i have an evostar 72ed  with fied flattener and was getting elongated stars on one side. I bought an adapter to thread the flattener  directly to the drawtube witch cured the problem. I was getting tilt when I inserted the flattener into the adapter that came with the 72ed.

I also have an SL2. Did you mod it yourself? I have modded a canon 600d and was thinking of doing my sl2 but there is no info online to do the mod like with the t3i. was wondering if the sl2 has the two low pass filters like the t3i, one that reduces ha and the one you leave in that cuts ir. 

You might find this article helpful . Its about what the best iso to use for the canon 800d but the 800d has the same sensor and digic 7 processor as the sl2.

geoff

 

 

 

 

 

 

 

 

i

[Chefgage]

On 23/03/2021 at 11:47, michael8554 said:

Bottom left stars are radially elongated.

All the rest are elongated TL to BR.

I'd sort that first - guiding ?

Michael

 

I am guiding using a zwoasi120mm mini. The guiding done with an asiair pro. The best error I can get down to is 2". As the mount only guides in RA and coupled with a known guiding  issue on the asiair then 2" is probably the best I am going to get. 

[Chefgage]

On 27/03/2021 at 14:10, gduffett said:

 

i have an evostar 72ed  with fied flattener and was getting elongated stars on one side. I bought an adapter to thread the flattener  directly to the drawtube witch cured the problem. I was getting tilt when I inserted the flattener into the adapter that came with the 72ed.

I also have an SL2. Did you mod it yourself? I have modded a canon 600d and was thinking of doing my sl2 but there is no info online to do the mod like with the t3i. was wondering if the sl2 has the two low pass filters like the t3i, one that reduces ha and the one you leave in that cuts ir. 

You might find this article helpful . Its about what the best iso to use for the canon 800d but the 800d has the same sensor and digic 7 processor as the sl2.

geoff

 

 

 

 

 

 

 

 

i

Thanks for that. Do you have a link to the adapter you bought please. I did not modify to 200d myself.

Edited March 30, 2021 by Chefgage

[gduffett]

I bought this in the US but I belive FLO has one too https://agenaastro.com/blue-fireball-m48-male-m54x1-male-adapter-m09.html the M54x1 male thread is what threads into the evostar 72ed drawtube , doesn't seem to be a very common size I couldn't find any in Canada and had to order it. Do you need to use an IR cut filter with your modded 200d? did you have the option to get a full spectrum or just a hydrogen Alpha modification?

[Chefgage]

On 30/03/2021 at 21:48, gduffett said:

I bought this in the US but I belive FLO has one too https://agenaastro.com/blue-fireball-m48-male-m54x1-male-adapter-m09.html the M54x1 male thread is what threads into the evostar 72ed drawtube , doesn't seem to be a very common size I couldn't find any in Canada and had to order it. Do you need to use an IR cut filter with your modded 200d? did you have the option to get a full spectrum or just a hydrogen Alpha modification?

Thanks for the link. I do not need to use a IR cut filter with my mod as I did not have the full spectrum mod.