I've got peter's 10" newt here for a while in an attempt to finesse the colmination on this F3.8 mongrel and am posting this so we can see where it is up to.
Stars are still a funny shape but compared to the viel shot which is where we started, it's a lot closer. FWHM is down to around 4.5 so it's getting there.
Cloudy now so all stop.
Just 6 Lum and 1 each RGB all 5minute binned x1 under the moon. Veil was 2min subs.
Hmmm, collimating scopes can be such a pain, I took the soft option and went to a refractor.... Although f3.8 is a light sucking ratio for sure.
253 looks ok, but the veil,it looks like the focuser moved on you, but with them all skewing to the left it does look as though there's a collimation issue too.
Last night is my second go at this thing, we seem to run out of sky whenever we get it close. But there's nothing like a big low F newt
I'm just using a laser, cheshire and ccdinspector peter but the other peter has a catseye kit he's going to dropin before flying out again.
I definately don't trust this laser and at this FRatio everything seems really touchy. At least I can leave it setup in the shed waiting for clear sky
Great to see you and Pete putting some effort into this beast Robin. It's always fascintated me every time I've looked at it (wistfully). It SHOULD be capable of some devasting pics on paper.
Really hope you get it singing. Then, for goodness sake, don't bump it!
You really do need to be using the Catseye gear, especially the autocollimator. I expect a mm either way on primary or secondary would be enough to knock it out at F/3.8
I wish Skywatcher or an Australian version of Orion UK would put out an F4-5ish 12" Newt with struts (CDKish?) to keep weight right down. Big secondary and 3" chinese corrector. Then again I also wish I had a cold beer and it was sunny right now.
Isn't carbon fibre heavier than aluminium though? I usually only need to focus once each night, sometimes twice after a few hours. I'd read that Peter Haese thinks his 12" RC is too big for a G11, thus the musings about a truss design. Still, the industry does seem to be taking notice of the steadily increasing number of amateurs getting hooked on astrophotography which has to be a good thing.
I don't think the tubes are aluminium, at least the GSO one I cut was steel. One site claimed the 10" one was 13Kgs but all of them only have 2" focusers and no info on the secondary I can find
Just looking at your stars Robin, and it may be something to check in on that none of your optics are warped, Ive seen very similar star shapes come out of my 254 when the primary mirror was warped (see astigmatisim).
A very quick way to see if you have a issue is put a eye piece in and go in and out of focus if your stars start roundish then as you get closer into focus they turn slightly oblong then on the other side of focus flip 90 deg.. Start hunting!
The biggest reason why i say this is your extra spike on the larger stars. The rest of it is coma as you probably well know!
You are also on the money for not trusting the cheshire and the laser at f4.74 my 254 is touchy as a bugger, at f3.8 0.5mm out of alignment means doom! Good luck
Cheers Brendan, It's a conical mirror and Peter has recently replaced the primary cell with a high end version but it will be worth a look if it doesn't come good. I'm still hunting around for spacers to adjust the mpcc distance and he's dropping in the autocollimator kit tomorrow. In the mean time it's a bit wet and overcast
ah well that kills that but still make sure that the secondary isn't suffering from anything ill.
As for the MPCC spacer if your using the baader one i just recently had one made up that is specifically for the job from Pro star I have yet to get it tested as the weather over here in WA has been shocking for nearly 3 months now, that and i havn't been able to do anything due to uni and work. But im hoping to get it tested during the week so ill let you know how it goes
I thought I'd try a barlowed laser before the other tools arrive. I got an old 2x barlow, put a circle of paper over the telescope end, put a laser into it and punched a hole in the paper to let the laser out. Putting that combo into the scope it generates a broad light circle on the primary lighting up the center spot. That reflects back and using a hand mirror inside the tube, angling it to see the paper on the end of the barlow up the focuser tube, you see the center circle from the primary. Now adjust the primary so that shadow of the center spot has the hole in the paper in it's center. This is not effected buy moving the laser around, you see the same result if you wobble the laser.
CCDInspector collmination routine was happy, it just revolved around in circles on a defocused star and after just one focused exposure, ccd inspector was giving pretty decent figures. Tilt and Collimation where 2% and 1.6", almost as good as my RC8 figures. FWHM on a random starfield was under 2.4, all looks great, but as always, the devil is in the detail. Stars are still warped, so I'm guessing the secondary is at fault and needs more work. So much for software tools.
Here's 253 again, 2minute subs this time to avoid the clouds and tuc with 30sec exposures. Definitely not a scope for clusters. Go much less than 30sec and I risk shutter artifacts
Got some M42 shots as well but what's the point More to come ...
Not bad at all Roin, the barlow laser is definately a way for you to get it close but like i said with the f3.8 you have to be 100 percent on the money to get it to hummmmmmmm.
once you get the cats eye collimation kit to start making things really tight then you will see the difference. I saw a massive difference when i got my kit together. the multi colour diffraction spikes are a dead give away for that.
If i was about your area i would be more than happy to come over and lend you my kit to get that 3.8 singing
that kills that but still make sure that the secondary isn't suffering from anything ill.
More to come ...
