The Golden Prawn - with AG12

[bmitchell82 (Brendan)]

they can be a pain in the arse when you don't have the right set up from what i have seen. I have not hit a snag yet and its not even focused to the main ccd, I will post up what im guiding on so you can pee yourself laughing! but hey its representative of the stars and if it moves it corrects and the stars are round. your setup is just a wee bit better than mine so you shouldn't have a issue.

[strongmanmike (Michael)]

Originally Posted by bmitchell82

they can be a pain in the arse when you don't have the right set up from what i have seen. I have not hit a snag yet and its not even focused to the main ccd, I will post up what im guiding on so you can pee yourself laughing! but hey its representative of the stars and if it moves it corrects and the stars are round. your setup is just a wee bit better than mine so you shouldn't have a issue.

I had a look at your OAG - very nice job...I couldn't see much difference between the before and after photos though so I must have been looking at something else..?

I want to go down the OAG path but I need to nail the correct spacing first so I know what Orion needs to make me exactly.

Mike

[bmitchell82 (Brendan)]

Non OAG
http://brendanmitchell.net/wp-conten...-animation.gif

OAG
http://brendanmitchell.net/wp-conten...-animation.gif

Like i said this is the white polished turd at work with massive PE at best!

This is what OAG has enabled me to do

http://brendanmitchell.net/wp-conten...0_25_25_30.jpg

Vs This

http://brendanmitchell.net/?page_id=...to=126&occur=1

Its worth the screwing around but yeah at the moment im guiding not on banana stars but comets with tails!

[multiweb (Marc)]

Originally Posted by strongmanmike

The heater strap is molded into the tube in-line with the primary mirror.
You can see it here at the back of teh tube (mirro removed) http://www.pbase.com/strongmanmike20...98033/original

Interesting to see it's fitted under the lining. Is it bulging or coming off the wall with the heat or do you regulate it so it's just warmish? So I understand it just warms the primary glass by proximity? Doesn't transfer any heat to the mirror by touching it right?

[strongmanmike (Michael)]

Originally Posted by multiweb

Interesting to see it's fitted under the lining. Is it bulging or coming off the wall with the heat or do you regulate it so it's just warmish? So I understand it just warms the primary glass by proximity? Doesn't transfer any heat to the mirror by touching it right?

The broad pad is molded onto the inside surface of the tube. It is designed to gently warm the air in the area in fornt of the mirror, warmer air can hold more moisture and thus slow or prevent the formation of dew, the moving air caused by the rear fans also helps here too and produces a laminar air flow .

Mike

[strongmanmike (Michael)]

Originally Posted by bmitchell82

Non OAG
http://brendanmitchell.net/wp-conten...-animation.gif

OAG
http://brendanmitchell.net/wp-conten...-animation.gif

Like i said this is the white polished turd at work with massive PE at best!

This is what OAG has enabled me to do

http://brendanmitchell.net/wp-conten...0_25_25_30.jpg

Vs This

http://brendanmitchell.net/?page_id=...to=126&occur=1

Its worth the screwing around but yeah at the moment im guiding not on banana stars but comets with tails!

OK I didn't look at your pages properly (I was at work) those results are quite telling....

I guess you haven't been using it for long but so far how easy has it been to find a guide star..?

More thinking to do

Mike

[mill (Martin)]

Very nice Mike
Love the color and sharpness of the picture.
Gotta love narrowband
On the subject of off axis guiders, sometimes it is a pita to find a good guide star
But normally you would find one good enough.

[bmitchell82 (Brendan)]

If you run a high quality guide camera, for example SX Lodestar and what im using at the moment is a SBIG 402-me, I haven't had a issue with finding a guide star yet. If worse comes to worse run it at bin 2x2.

And yes I have only just finished it mid last month, but I am convinced that it works as described and kills all flexure which big newts are renowned for. The thing that will make it hard for you is the back focus from the whynn corrector and fitting everything in between that and the sensor.

[strongmanmike (Michael)]

If you run a high quality guide camera, for example SX Lodestar and what im using at the moment is a SBIG 402-me, I haven't had a issue with finding a guide star yet. If worse comes to worse run it at bin 2x2.

No worries there I use an SXV-H9 and it is excellent, very small and compact.

And yes I have only just finished it mid last month, but I am convinced that it works as described and kills all flexure which big newts are renowned for. The thing that will make it hard for you is the back focus from the whynn corrector and fitting everything in between that and the sensor.

Yes but I thiiiink I can squeeze one in...?

I'm going to try stiffening up my guide scope first..then, we'll see

Even consitent 10min with 12" at F3.8 would go very deep

Mike

[Phil Hart]

Originally Posted by strongmanmike

I agree, I am now pretty sure the star issues is a spacing problem, must be very slightly too long or two short, probably only a mmm or two?.. not sure how t happened either as I used all the right measurments and the adpater made by OO measures up to the specs I supplied
Mike

Did you allow for the optical thickness of the filters and ccd sensor glass when you calculated all that? As I recall, if you have a filter 2mm thick that's only equivalent to 2/3 the amount of air.. say 1.3mm. If not you could move in by 1mm and see if that helps? Or maybe you figured all that already.

Your extreme corner stars are the same shape as mine on the Tak E160 f3.3.. but I'm using much smaller sensor. Tweaking spacing may help but you may be close to the limit of what you can achieve at f3.8.. it is a compromise after all!

And I understand what you mean by going round in circles trying to collimate using the camera.. you make one tiny adjustment and then the star has moved and you have to be looking at a star right in the centre of the frame so then you have to recentre.. blah.. impossible i say! i gave up too..

Phil

[bmitchell82 (Brendan)]

well like i have shown, since doing that mod, its been keep 3 out of 12 odd images because of bad guiding and even those images where pretty average. now i keep everything bar the meridian flips images .

Im even going to start moving out to 15 min Lum and possibly 10min rgb because of the confidence i have with it now.

[strongmanmike (Michael)]

Originally Posted by philiphart

Did you allow for the optical thickness of the filters and ccd sensor glass when you calculated all that? As I recall, if you have a filter 2mm thick that's only equivalent to 2/3 the amount of air.. say 1.3mm. If not you could move in by 1mm and see if that helps? Or maybe you figured all that already.

Your extreme corner stars are the same shape as mine on the Tak E160 f3.3.. but I'm using much smaller sensor. Tweaking spacing may help but you may be close to the limit of what you can achieve at f3.8.. it is a compromise after all!

And I understand what you mean by going round in circles trying to collimate using the camera.. you make one tiny adjustment and then the star has moved and you have to be looking at a star right in the centre of the frame so then you have to recentre.. blah.. impossible i say! i gave up too..

Phil

Hi Phil

I extended the distance 1mm (with a gasket made from plastic bucket lid ) and the corners are deffinitely better ..so it (predominantly)wasn't a collimation issue, hence the going around in circles when collimting on camera . Yes the 16803 sensor at F3.8 is a challenge but worth the trouble I think. The design of the fast Newt, even with mega bracing, is pushed to the limit with a camera like the PL16803 and CFW-5-7 attached!..variations in star shapes across the sky as a result of tiny amounts of flexure is probably inevitable and hard to eliminate 100%..? In the end the massive field of view at good image scale with a high incoming flux density were the two main reasons for going down this route - I have a Starfire after all and that is hard to beat for imaging resolution

Originally Posted by bmitchell82

well like i have shown, since doing that mod, its been keep 3 out of 12 odd images because of bad guiding and even those images where pretty average. now i keep everything bar the meridian flips images .

Im even going to start moving out to 15 min Lum and possibly 10min rgb because of the confidence i have with it now.

If you read this Brendo I am up now so ring me!

Mike

[gregbradley]

Interesting Mike. So that means you need to extend out further. I got some spacing rings from Astrodon for my MMOAG. Each one is 5mm. Something like that would be handy as its all black anodised aluminium and slides over the threaded fittings to pack it out the right distance.

If you experiment with any sort of packing material and get the exact distance you could then get a more permanent solution with one of these rings made up. Moog could probably make one for you cheaply or Precise Parts - more expensive but its correct every time.

Greg.