Pillars of Creation

[RobF (Rob)]

Originally Posted by peter_4059

I've also encountered some issues in DEC where I've had to increase the guiding (rate?) from 0.3 to 0.6 in EQMOD to get Guidemaster to complete the calibration - it was complaining there wasn't enough movement in the star during calibration. I'm guessing this is a backlash issue however this seems to have got worse (since I changed the balance) for some reason. I'm wondering if something has become loose within the gear train? Is there a way to measure backlash in DEC - I know Guidemaster reports if it detects backlash but doesn't really quantify it. I assume the fix is to adjust the gear mesh?

Peter

I find I have to increase my pulse guide rate up to between 0.4 to 0.6 to keep Guidemaster happy too Peter. I seem to be able to get consistently get much nicer stars out of GM though, even though it says I've got quite a bit of DEC backlash. One day I'll work up enough guts to dig around in there....

Fantastic pic! Have enjoyed seeing what's coming out of that newt lately.

[Hagar (Doug)]

Well captured Peter, The detail you have managed to capture with the DSI is outstanding. Again you have nailled the focusextremely well. I wish I could do half as well.

Keep at it Mate.

[peter_4059 (Peter)]

Interesting that you've encountered a similar guiding issue Rob. I can't understand why it's become an issue after so long? I agree with you re GM - I seem to get a better result from it too however I get the same message re dec backlash - perhaps everyone gets this message - might be worth a poll as it might just be a bug.

Doug - the focus is easy given I have a very basic setup - my secret is
Orion motor focuser fitted to a GSO Crayford
Shoestring FCUSB
FocusPal software
Bahtinov mask

I overlay Magnifier software over the DSI live view with exposure set at 0.5 secs and focus on a bright star.

Peter

[RobF (Rob)]

I'm pretty sure I do have backlash - can see it takes a while for the mount to reverse in DEC when I have the slew rate turned right down to absoute min in EQMOD (gets lower than hand paddle).

What's the Magnifier software Peter? Sounds like a clever addition to the focusing routine.

[peter_4059 (Peter)]

Rob,

Here's a link:

http://www.iconico.com/magnifier/

Enjoy.

Peter

[Rastas]

Originally Posted by Dennis

A stunning image Peter; great image scale and a large field too – well done! I hear ya about the elongated stars – I’m still ironing out my set up too!

Cheers

Dennis

Peter
You have to have egg'y stars in that photo. It is the Eagle nebula afterall.

[Prickly]

Absolute ripper Peter.

What focal length are you guiding at? I wonder whether adding a barlow/OCR would help with the stars. Usually I guide with the C90 at 1m focal length and the stars are pretty sharp with the imaging at 800mm.

Have heard it said you should guide at 2x your focal length, in the days when it was all done by hand. Mind you, ccds are a lot better at correcting than the human eye so maybe it wouldnt make a lot of difference.

Cheers
David

[peter_4059 (Peter)]

Thanks David. I'm imaging at 1250 mm and guiding at 500 mm. I've also heard the 2x rule but thought the CCD guiding system was capable of sub-pixel accuracy such that this wasn't an issue.

After reading another thread on guiding I'm wondering if my guide star wasn't bright enough for accurate centroid determination. I've been using the star brightness chart in Guidemaster to adjust the number of stacked frames to ensure the chart doesn't max out. There is no reference to the chart in the instructions but I guess it is possible that it needs to be at the top of the chart to be bright enough.

Peter.

[Prickly]

Brighter guide star is well worth a try Peter. I know for a fact that balance issues caused eggy stars for me in my second last image - might be worth checking the balance of the scope in various positions too just to make sure, although I think you mentioned this was ok.

Like Jase said - there is more detail in your image if you stretch it. Also I regularly do an artificial darkframe in Pixinsight LE which helps too. Pixinsight is great for stretching because you can zoom in to 10x (more if needed) with the histogram to make sure you are not clipping it.

Im really amazed with this image how sharp the stars are. It would have me thinking twice about an RC scope. Can see Im going to need one of these GSO 10 inches.

Cheers
David

[RobF (Rob)]

Thanks for this link Peter.
Have had my first opportunity to play tonight, and certainly a nice help with Bhat mask and Liveview on the canon.

Rob

Originally Posted by peter_4059

Rob,

Here's a link:

http://www.iconico.com/magnifier/

Enjoy.

Peter