NGC 6744 first light

[Jbunky86 (Jason)]

Hi everyone after what seemed like ages trying to sort out my new scope and wrestling with guiding i managed to get capture this.

Looks like my collimation is slightly out and i still have a few things to sort out with camera alignment.

Thanks for looking

1 hours worth of data
QHY10
GSO 8" F4 CF newt
C5GT mount
Orion mini auto guider
50mm guide scope

cheers

[tilbrook@rbe.ne (Justin Tilbrook)]

Nice start Jason!

Certainly takes a while to sort out the gremlins.

Cheers.

Justin.

[Jbunky86 (Jason)]

Thanks Justin,
I noticed we have very similar gear. Did you find your getting vignetting with your 35mm chip?? I seem to be, also i suspect my camera is not sitting square on the focuser. Im wondering whats the best way to line everything up.

cheers mate

[tilbrook@rbe.ne (Justin Tilbrook)]

Originally Posted by Jbunky86

Thanks Justin,
I noticed we have very similar gear. Did you find your getting vignetting with your 35mm chip?? I seem to be, also i suspect my camera is not sitting square on the focuser. Im wondering whats the best way to line everything up.

cheers mate

I'm running a DSLR canon 1100D which is not 35mm chip size so no problems there fortunately.

I think PeterM. from Adelaide is running the same setup as you, might be worth sending him a PM to see what he's done.

Cheers,

Justin.

[David Fitz-Henr]

Yes, a good start and not bad for just 1 hour of data. Collimation may be slightly out as you say. When I lock my adapter / camera in the focuser I check that there are no gaps between the adapter flange and the focuser as/after I tighten the set screws. However, your image looks like a general collimation issue to me - do you use any tools (eg. laser collimator,etc) to align the mirrors?

[Peter.M]

The qhy10 is a big sensor for a fast newt, you need to make sure it is as close to the tube as you can. Even then I think you will find a very large secondary is needed to fully illuminate the chip. The Orion optics ag8 uses a 90 mm secondary from memory. Personally I think that smallish fast newts lose too much because increasing the secondary size effects the obstructed area far greater than larger fast newts.

And I use the smaller qhy9 for reference.

[Peter.M]

I did some measurements on my GSO 8 inch F4 and plugged the values into NEWT.

The parameters were

secondary = 70mm
focuser min height = 70mm (gso 10:1 crayford)
spare in focus = 10mm (I guessed this, it is how far out the focuser is when the camera is focused)
tube diameter = 225mm
additional height for camera = 56mm

the value it predicts is 100% Illuminated Diameter: 11.38 mm
Your qhy10 has a diagonal of 28.4mm to cover this with the 100% rays your secondary would need to be a minimum of 82mm

[Jbunky86 (Jason)]

Thanks for all response guys. Looks like I will have to play around with my secondary sizing and focuser. Cheers Jason.

Oh yes I use catseye collimation tools, but I am a bit of a bigginer so still learning how to get everything spot on.

Thanks again

[Ross G]

Nice galaxy photo Jason.

A great start.

Ross.

[Peter.M]

Just to make it clear, while increasing secondary size will help vignetting it will also make collimation more of a pain as the weight of the secondary will cause more movement as the telescope changes orientation. It always seems to be a balancing act with newtonians.