NGC 2997 with Ed80

[Tony Leece]

High winds, poor seeing and clouds made for a short imaging session last night, but i managed some subs on galaxy NGC 2997 in Antlia.
Also picked up NGC 3001 too

2 hours 15 minutes of unguided 5 minute subs

Skywatcher ED80
Azeq6 pro mount
Zwo 533 camera @ -5 (tried -10 but cooling fan was at 100%)
Baader 2" IR/UV cut filter

From my Bortle7 Perth backyard

[raymo]

Nice job. Has anyone asked you why you are using your little 80mm
rather than the 250mm, which would give great results in approx 1/8th
of the exposure time, with the bonus of better resolution?
raymo

[Startrek (Martin)]

Tony,
Great effort with that small refractor
Well done !!
I agree with Raymo , Galaxy imaging is more suited to the bigger scopes with more light gathering power and resolution ( 8” and above )
Even an 8” f5 Bintel newt ($549 ) on that AZEQ6 with your 553 would yield great results.In saying that the longer focal length (1000mm) and aperture would require guiding at a image scale of 0.78 arc sec per pixel to take advantage of resolution with longer subs.You can take 60 sec unguided subs with an 8” but your PA has to be sub arc minute and your holding back the capabilities of that 533 camera.
Cheers
Martin

[Tony Leece]

Thanks Raymo. I have tried the newt a few months ago but it was a bit of a failure. Since then I have fallen into using the ED80 as its easier and more forgiving.
Also I made a home brew dovetail bar of dubious accuracy
I will hopefully have the funds shortly to sort everything out and dust the old girl off

[Stephane]

Tony, this is an awesome image. You got some nice colour. Nice work.

Regards,
Stéphane

[Tony Leece]

Thanks mate

[raymo]

If the main problem was the dovetail bar, assuming that it secured the scope
properly, any cone error introduced by the inaccurately made bar can easily be adjusted or shimmed out, and then you can get on with some seriously deep imaging.
raymo

[Tony Leece]

Oh brilliant, are there any YouTube videos of anything on doing this?
I have heard of cone error but don't know what to do mate
I will probably get a new dovetail in time but if I can do anything in the mean time that would be awesome

[Startrek (Martin)]

Originally Posted by Startrek

Tony,
Great effort with that small refractor
Well done !!
I agree with Raymo , Galaxy imaging is more suited to the bigger scopes with more light gathering power and resolution ( 8” and above )
Even an 8” f5 Bintel newt ($549 ) on that AZEQ6 with your 553 would yield great results.In saying that the longer focal length (1000mm) and aperture would require guiding at a image scale of 0.78 arc sec per pixel to take advantage of resolution with longer subs.You can take 60 sec unguided subs with an 8” but your PA has to be sub arc minute and your holding back the capabilities of that 533 camera.
Cheers
Martin

Apologies Tony for getting carried away
When I see these results from a smaller scope I kinda get get excited for the imager and what could be achieved with upgraded gear
Got ahead of myself
Apologies
Again well done !!

[Tony Leece]

No Apologies needed Martin, I really appreciate your comments immensely mate

[raymo]

Hi Tony, Cone error is when the scope is not perpendicular to the RA axis of
the mount[parallel to the saddle that the dovetail bar fits into.
Scopes normally come with adjusting screws on their dovetail rails.
You don't have that luxury, so you could use very thin metal shims on the bottom of your dovetail bar, and once correct alignment is achieved glue them in place on the bar. Just insert a shim between the bottom of the dovetail and
the saddle at one end or the other, and tighten the dovetail.See if it makes things better or worse.
If it improves things add more shims until error is eliminated, and obviously
if it makes things worse, shim at the other end instead.

To check error before you begin adjustments you ideally need a reticle or crosshair eyepiece, or an eyepiece you don't care about much which you can mark in
the centre with a fine marker pen.
Take rig outside and find a small target at least a few hundred metres away.The lamp unit on top of a street light would do.
Rotate mount so that counterweight shaft is parallel to the ground.
aim the scope to centre the target on the cross hairs and lock the scope.
Rotate the mount so that the CW shaft is parallel to the ground on the opposite side of the mount, and see if the target is still centred in the eyepiece.
raymo

[Tony Leece]

thanks mate i will give that a go, cheers