Single sub - Orion Nebula

[Cimitar (Evan)]

Despite looking a little painted after bringing out the faint stuff - it's not bad for a single sub: 270sec ISO 800 (stock Canon 600D).

I was testing the new mounting bracket for my guide scope after buying some aluminium from Bunnings and building an adapter onto the Losmandy dovetail bracket. Now I can have my Stellarvue 50mm guidescope + red dot finder side-by-side. It's the little things in life!

Taken on 3 November through an 8" LX200. Suffice to say very happy with the new guiding rig

Thanks for looking. Cheers, Evan

[cometcatcher (Kevin)]

Lovely shot Evan.

[raymo]

I REALLY don't want to rain on your parade, but the stars are enormously
and oddly elongated, so it would seem that the guiding was very poor indeed,
or am I missing something? Maybe the mount was nudged during the exposure.
raymo

[Cimitar (Evan)]

Originally Posted by cometcatcher

Lovely shot Evan.

Thanks Kevin

[Cimitar (Evan)]

Originally Posted by raymo

I REALLY don't want to rain on your parade, but the stars are enormously
and oddly elongated, so it would seem that the guiding was very poor indeed,
or am I missing something? Maybe the mount was nudged during the exposure.
raymo

Hi Raymo,

The stars do look like little worms. I went back and looked at the raw image and they look OK (see attached - full zoom). Not quite perfect but fairly round.

It might have been a processing artifact If so I'll have to keep an eye out for that in the future. There was also the slightest breeze that night. So hard to get a still night these days.

Cheers, Evan

[cometcatcher (Kevin)]

The stars look pretty round to me Ray.

[raymo]

If you enlarge your screen to at least 150% Kevin, preferably more, you'll
see that the brighter stars especially are elongated more or less vertically.
Unless my comp has gone weird on me, that is.
raymo

[ZeroID (Brent)]

There does appear to be a small vertical component of about 2 pixels in the image. For a single shot 270 sec image I would say it was pretty dang good. It may be that the focal plane is not exactly parallel with the image plane, not sure. Multiple images stacked with shorter subs would possibly 'cure' it. But for a single frame I am quite impressed with colour and resolution and the guiding is pretty dang good IMHO. Any filters used for LP ?

[cometcatcher (Kevin)]

Originally Posted by Cimitar

...

The stars do look like little worms. I went back and looked at the raw image and they look OK (see attached - full zoom). Not quite perfect but fairly round.

It might have been a processing artifact ...

I'd say so. They are not on the raw image.

[Cimitar (Evan)]

Originally Posted by ZeroID

...For a single shot 270 sec image I would say it was pretty dang good. It may be that the focal plane is not exactly parallel with the image plane, not sure... Any filters used for LP ?

Thanks for your comments Brent, much appreciated
Are you able to please elaborate when you say - focal plane not being parallel with the image plane? I love to learn and that sounds like something I should try to avoid if possible? Is it related to the guidescope not being perfectly aligned with the main tube or the DSLR not mounted at 90degs to the main scope? Both of which are quite possible on my existing setup

RE: Filters - none. Gunnedah only has 10,000 people so we're very fortunate to have some beautiful dark skies.

[MarcusG]

Lovely shot mate!

[ZeroID (Brent)]

Originally Posted by Cimitar

Thanks for your comments Brent, much appreciated
Are you able to please elaborate when you say - focal plane not being parallel with the image plane? I love to learn and that sounds like something I should try to avoid if possible? Is it related to the guidescope not being perfectly aligned with the main tube or the DSLR not mounted at 90degs to the main scope? Both of which are quite possible on my existing setup

RE: Filters - none. Gunnedah only has 10,000 people so we're very fortunate to have some beautiful dark skies.

Lucky you ... got to contend with a fair bit of sodium and mercury at my place.
Focal plane and image plane. The cause is focuser droop which tilts the camera sensor with respect to the plane of focus from the objective ie not square to the optical axis. Puts objects at top and bottom of the image ever so slightly out of focus even if the centre looks ok. Not sure if this is your symptom or cause but for short focal length scopes with a small depth of focus it can be critical. Longer focal lengths it is not so apparent.

For a long exposure as yours though even just a small worm error could be enough to induce some tiny smudge effect. As I said shorter image times and stacked images would probably eliminate it. I'm super envious of your dark skies though.

Keep it up

[Cimitar (Evan)]

Originally Posted by ZeroID

Focal plane and image plane. The cause is focuser droop which tilts the camera sensor with respect to the plane of focus from the objective ie not square to the optical axis...

Great, thanks mate . Appreciate you explaining that. It makes sense and might explain an issue I was having before with my meade microfocuser.

[Cimitar (Evan)]

Originally Posted by MarcusG

Lovely shot mate!

Thanks Marcus

[Adriano]

Nice image of M42.

[DarkKnight (Kev)]

I came across this the other day and wasn't quite sure what it did

https://www.bintel.com.au/product/zwo-t2-tilt-adjuster/.

Reading this thread has probably given me a clue.

[Cimitar (Evan)]

Originally Posted by DarkKnight

I came across this the other day and wasn't quite sure what it did

https://www.bintel.com.au/product/zwo-t2-tilt-adjuster/.

Reading this thread has probably given me a clue.

I think your spot on Kev
I noticed my camera sagging was caused by 2 things primarily: Firstly the thumbscrews I was using on my microfocuser weren't up to par, and secondly the 2 inch spacers I was using inside the microfocuser had the smallest amount of give. It's amazing the little tips you pick up along the way

Cheers, Evan