North Group APOs

[wasyoungonce (Brendan)]

Alrighty...I'm outside ATM and I focused & backed it off a touch!...What a change ...all good.

I did star tests...all good.

I'll post some happy snaps later. Thanks to all indeed!

[Octane (Humayun)]

Bren,

Happy to hear that. Happy imaging.

H

[DavidU (Dave)]

That's great news Wasyoung. Look forward to some piccies.

[wasyoungonce (Brendan)]

Dad left his page up..Silly him. He loves his daughter Emma most and he is still outside looking at the sky! What a nerd, but a cutie at the same time. PS i hate maddie.

[MrB (Simon)]

Originally Posted by wasyoungonce

Dad left his page up..Silly him. He loves his daughter Emma most and he is still outside looking at the sky! What a nerd, but a cutie at the same time. PS i hate maddie.

Haha, how funny is that!
Hello Emma
I wonder if dad's gonna find it as funny as I do?

[wasyoungonce (Brendan)]

Dads back....1 x daughter for sale...going cheap!

[Octane (Humayun)]

Hahaha, that was gold!

Emma rocks!

H

[MrB (Simon)]

I'm still laughing.... hahaha

[Coops (Sean Cooper)]

Hello

For those who didn't get replies to Gilman, I've been emailing him for the last couple of days with success.

I initially went through the Alibaba link getting a reply couple of days later.

[wasyoungonce (Brendan)]

Now my daughter is back at the "home"...I can post & leave web pages up!

Here are some quick pics. Outside focus/inside focus x 2 (diffraction rings). I used Antares for this.

M8 (enlarged crop) focus backed off, 60s sub.
M8 enlarged crop 300s sub.

M8 crop enlarged focus backed off (only a very very slight hue)...and the same with focus done at 10X liveview (notice the hue).


edit:
One thing...the outside focus diffraction rings had a blue hue on the upper right quadrant and violet on the lower left! pretty much same inside focus diffraction rings.

Focusing was accomplished by 10X live view then backing off & taking 60s subs to see the result. This is not ideal and easy to get frustrated. Anyone know if a Bahtinov mask can be designed for yellow wavelengths diffraction focus pattern? Indeed what wavelength are the masks made for?

I did some Avi's of focusing in/out but have not reviewed them yet.

Once again thanks to all members for helping me with this! and putting up with my wayward daughter!

[DavidU (Dave)]

The mask will focus the full spectrum of the star. If a slight Longitudinal aberration has the violate end more out of focus than the yellow/green (quite typical) I would use the mask with a yellow filter then a blue to see the difference in focus.

[DavidU (Dave)]

Also I would say your collimation is slightly out or a tilt in the camera plane.
Trow up a diffraction pattern like #2 and shift the scope around so the image goes around the camera chip and see when the offset violet becomes more uniform.

[wasyoungonce (Brendan)]

Originally Posted by DavidU

Also I would say your collimation is slightly out or a tilt in the camera plane.
Trow up a diffraction pattern like #2 and shift the scope around so the image goes around the camera chip and see when the offset violet becomes more uniform.

Thanks David. yep will try that. But...clouds are back!

Is it worth getting or using an artificial star for this?

[DavidU (Dave)]

Yes you bet. I have built a white on and a blue one. The trick is to have it 300+ feet away from the scope of it will be impossible to throw a diffraction pattern. During the day (direct sun) a 10mm ball bearing on a stick works a treat !

Originally Posted by wasyoungonce

Thanks David. yep will try that. But...clouds are back!

Is it worth getting or using an artificial star for this?

[wasyoungonce (Brendan)]

1st processed pic with 127ED and re-focus technique, M8.

Not posted in Deep space threads ...it's kinda an over done traget...anyway it turned out ok.

I think it's missing some fine detail and I'm guessing as I get better at focusing this will be better. I also need to track down why one side of my outside focus diffraction rings look violet & the other blue! As David said, more than likely due to camera nose piece not square or such like.

So, here's proof. The scope does work!

edit:
oh.. DSS stacked 15 x 5 min subs & darks from my dark library (no flats). DSS reported FWHM of around 5.1 to 6.1...that's a little high!....anyway...Curves, levels, some selective colour adjustments, and one smart sharpen in CS3.

[wasyoungonce (Brendan)]

Just a quick question.

After looking at the inside/outside diffraction patterns...they are compressed top right.

I also noticed a pic I took of NGC6744 showed coma in dim stars, same direction as compressed diffraction pattern.

So I need to collimate. I know I can use an artificial star (if I could get the distance between myself and the artificial star) but what about a Cheshire eyepiece or laser collimator or such like.

What's best, cheapest & easiest? I imagine a Cheshire?

[DavidU (Dave)]

A refractor Cheshire.

[wasyoungonce (Brendan)]

Thanks David.

forgot to ask..is a laser collimator any better (probably is for a newt) or is it hype not needed especially for a refractor.

[DavidU (Dave)]

A laser is good for collimating the focuser. Just remove the lens cell and replace it with a round piece of white paper with the exact centre marked, so if the focuser is spot on the laser will be dead centre .Make sure the laser itself is collimated (turn it around when in the focuser).

Originally Posted by wasyoungonce

Thanks David.

forgot to ask..is a laser collimator any better (probably is for a newt) or is it hype not needed especially for a refractor.

[DavidU (Dave)]

http://www.spacealberta.com/equipmen.../collimate.htm