Does anyone know what might be causing this???

[Mick UK]

This image is 10 x 3.30mins with darks added in DSS.

It was taken using my skywatcher 250pds newt with a modded canon 350d.

I collimated the scope before taking the images using my hotech laser collimator and i've just recently collimated the laser so i done think this might be the problem??

I have a dew sheild on my scope to stop my secondary mirror misting up(which it tends to do quite a lot) which i made from a camping mat and flocked with black felt.

Im wondering if the dew sheild was causing the problem but it certainly looked to be seated perfectly when i put it on the scope and was a nice tight fit so it should'nt have moved anyway as there was no wind at all last night .

anyone have any ideas??

[Jannis]

*waits for someone to respond to this and it looks ratehr confusing to me...*

I have to say though, something is way off, and i don't think it's the dew shield either (wouldn't it be even all around, and still in focuse and clear in center?), and collimation after adjusting with laser is extremly little likely (at least something this serious).

from the looks on the shape from the "stars" on the top right there, it looks like focuse if way off. Isn't it the 2nd mirror you see in the middle of the "stars"?

Kind of looks like the camera wasn't hanging stright and therefore focuse changed from top right to bottom left, but i can't belive that's possible either, as you'd notice it if camera was mounted That uneven. And i don't even think it's physically possible anyway...

[Mick UK]

I used a Bahtinov mask to achive perfect focus so i can only assume the problem doesnt come from there.

Funnily enough i was imagine the moon a little earlier last night before i decided on doing some Deep sky imaging and the moon was clear and sharp at around 600x using a tal 3x barlow and spc900 webcam!.

Somethings gone awry somewhere.

[Mick UK]

I have just gone through every single frame and they are all like the one shown, i thought perhaps the mount might have juddered on one of the frames, but obviously not.

[FraserClarke]

Oooh, that's a funny looking one :-\

Looks very much like a hugely tilted focal plane. Definitely seeing some defocus across the image, and vignetting on the right (wouldn't worry about that - quite normal). Why is there a chromatic difference across the field though? (only seeing green on the right???).

Would check the camera mounting first perhaps??

[Tim]

Have another look at the secondary Mick, I'd guess it has rotated relative to the focuser. It would still look ok on the laser though.

[Mick UK]

"Would check the camera mounting first perhaps??"

I think you could be right here, when i got focus with the mask i remember the star i used was off to the left of the center a wee bit, looking at the image, that area seems fine, i wonder if i havent pushed the camera adaptor in square and nipped it up slightly off.

good shout:icon_salut:

[Tim]

ps, how do you collimate a hotech?????? and did you need to?

[Mick UK]

TJ i did need to collimate my laser as it was quite a ways out, it was a bit of a pain as it was the first time i had done it, but now i understand whats needed to be done its quite easy.

I made a jig for the laser from a piece of scaffolding board about 12" x 6" and used 4" nails to form a X shape for the front and back of the laser to rest in, this enabled me to rotate the laser and get it spot on.

Ive made a thread about it somewhere, i'll stick a link to it on this one if i can find it.

[Steve]

... i've just recently collimated the laser ...

Hotech lasers don't need collimating. Best that you contact your supplier.

[barkis]

Looks like a misaligned camera. Could it have slipped in the focuser, or something loose in there?

Ron.

[Steve]

... with a modded canon 350d.

Where was the camera modded? Is this the first time you have used it since it was modded?

[Mick UK]

Steve my Hotech was out by quite some distance, i didnt realise at the time that i could have sent it back to FLO for collimating, but im now glad i didnt, ive learned something new!

I think the camera is the problem, im pretty sure it wont have been sat in the focuser properly, thinking back, ive had probs getting it in due to the fact the connector im using doesnt have any threads to accept my light pollution filter so i just use to very fine strips of that chrome tape to hold it in place. I really do need to get arung to buying the proper connector! ... i'll check it out tomorrow on a distant object or later tonight if the sky clears.

Steve, no its not the first time ive used it, ive used it dozens and dozens of times, and the camera was modded by myself, i remove the IR blocking filter and just left it without any replacement on it as i was informed at the time i'd only need to put a clear glass filter on if i wanted to use the camera for daylight photography. (which i didnt)

[Mick UK]

Found out the problem of the false colour in that image!

I'd forgot that a while back i was playing around with my camera settings and i changed the colour space from RGB to Adobe RGB!! i completely forgot about doing it:o...... in future, if im going to mess around with the settings, i think i will tie a tag on the camera to remind me of what i'd done!

[Photosbykev]

If you are shooting in raw then then Adobe RGB colour profile is better than the sRGB profile for capturing subtle colour shifts. It's easy enough to convert from aRGB to sRGB once you've processed the final image