Eta, a few more bells and whistles.

[tilbrook@rbe.ne]

Hi,
Here’s another image of Eta, please disregard the star images. Although I’ve got closer to the correct spacing for the coma corrector it’s still not producing the sharp round images I would like.
The BINTEL corrector is actually designed for F/4.5 but they say it will work at 3.5 to 6.0, I have my doubts.
What correctors do others use for an 8” f/4 astrograph??
To the image.
This time I have more data, 40 minutes in total, would have liked more but the cloud rolled in. I managed to preserve star colour this time, needed to get quite heavy handed to bring out the red in the nebula. My canon 1100D is not modified, so doesn’t register in the red very well.
I’ve been using a lot of the tips you guys have supplied and I think I’m improving?
Maybe the weather will be kind on the weekend so I can get more data.
Equipement.
Telescope 8” f/4 astrograph – HEQ pro 5 mount – Orion mini guider.
Camera. Canon 1100D – BINTEL 2” coma corrector.
8 x 5 minute subs – 7 x 5 minute darks – 7 flats – 7 bias, at ISO 400.
Median stack in DSS.
Processed in Photoshop.
Cheers,
Justin.

[Ross G]

A very good photo Justin.

Nice colours.

I have an 8", F4 Vixen. I have the Vixen coma corrector and an MPCC, but I'm not happy with the stars with either of them.


Ross.

[tilbrook@rbe.ne]

Thanks Ross,

Certainly frustrating !!

Justin.

[Peter.M]

I have the same scope and I use the Baader MPCC, one thing I can tell you about the stars is you need VERY good collimation. With my tools I am able to achieve perfect collimation, and even then if the focuser bends the metal when it is under load ( when I attach my camera/filterwheel/OAG/guidecam) I still wont get perfect stars in the corners.

[tilbrook@rbe.ne]

Hi Peter,

Yes on top of the collimation, I make it part of the routine to do this just before imaging. It amazes me that just about every time it needs a slight tweek, I think this may be due to temerature change in the observatory, it gets quite hot during the day as the observatory is made of steel.

Iv'e got collimation down about 5 minutes, took a lot longer when I first got the scope.

Cheers,

Justin.