OK guys. Nowhere near the Dennis/Rob T class but then neither was the seeing!
Thought I'd give the 9.25 a run last night to see what we'd get.
Seeing wasn't too good but the image shows an improvement on prior efforts with the SCT and that's all that matters.
No motor focus or cooling, but did have the new dew heater running, which I think made a difference.
Managed to adjust our capture settings for a more natural appearance and this time we've caught some extra detail like extra swirls in a few of the belts and some extra "spottage"
Hey Asi Thanks for the encouragement. It's nowhere near as good as the image you've posted in the last half hour but I'm workin' at it. My wavelets was very different to yours. I worked sliders 4,5 and 6 pretty hard. From memory I think 6 was about 65, 5 around 50 and 4 about 30. I sort of work a sliding system from 6 the hardest, downwards. I'm fascinated by your experiment with using just the one slider. I still don't think I've got collimation right??? The star test looked ok though, although I noticed my central obstruction looked bigger on one side of focus than the other. Could I be dealing with a problem primary perhaps???
Paul Re: collimation - I suspect this is one area where I can still make great strides. To my eye it looks OK, but I'm sure my eye is just simply not experienced enough. I'm seeing a nicely positioned central obstruction and concentric rings, but I've perhaps not had good enough seeing to crank it up to really high mag and test at that level. Last night I star tested with the 10mm XW
If your seeing will let you have a go at trying it using the NexImager and barlow on the laptop (or leave the barlow out if it's too much).
In some situations I've found that its' helpful, if for nothing else than keeping the star in the center of your imaging train. If the star image is out near an edge using an eyepiece then curvature can affect what you see and the position of the diffraction rings.
Paul Re your comment: "If the star image is out near an edge using an eyepiece then curvature can affect what you see and the position of the diffraction rings." I have no idea what that means in terms of collimation, given I check the diffraction rings only when the image is centred in the ep?????
When you adjust the collimation screws the star will move out towards an edge of the field of view because the secondary mirror is moving. You then recenter the star. If the star is not well centered then, as I understand it, because the star is now an extended object rather than a point souce and the scondary is convexly curved, the appearance of the diffraction rings can be affected by the curvature of the mirror.
If I'm being really pinickety on a night of imaging, I'll use my ToUcam and the reticle function of K3CCDTools to make sure my defocused star is dead center of the screen. That way I can be pretty confident my diffraction rings are off center because of collimation and not because of where the star is in on the secondary.
Plenty to be learned here Matt, thats for sure! Yes, up to only last night I've always used waveletts similar to you ie: #6-30 to 40 / #5-24 to 30 etc etc etc. I'm stacking the same AVI right now as ANOTHER experiment, this time using 1 & 2 waveletts only. (depends on the amount of frames stacked here, as to how far you can push them)
I don't collimate until the scope has reached ambient. I was collimating using 2X barlow + extension tube + 7.5mm EP the last few nights....Now I use 2X barlow + extension tube + toucam. I see better 'quality' diffraction rings/central obstruction on the laptop than by eye threw an EP. Try it. (On a fairly bright star close to the intended target) You'll have to boost/tweak gain & gamma to get a good image.
I think cooldown is just as important as collimation with SCT's. I set mine up just after sunset, cover it & forget it. By the time Jupiters high enough, I'd say its very close to ambient, even without the cooler.
Paul. Was just a bit confused coz I've been reading different ways to collimate an SCT. The way I've been working is to start with the star in the centre of the field of view and de-focus to get diffraction rings. Then judge how central the obstruction is and how concentric the rings are. If they are out, move the image around the field of view to find the spot where things look more centred and concentric, then turn the secondary collimation screws to bring that improved image back to the centre of the field of view. Have another look and repeat if necessary. If the seeing allows, insert higher mag ep and do it all again. Asimov... glad it all makes sense to you, you clever fellow, you!
Thanks Mike That was something I was really keen to achieve with this image, even if it looks a little soft. Getting those more natural eyepiece tones is actually quite a challenge. It's so tempting during Registax and post-process to push things too hard. I also tried a few things differently during capture, which made the overall experience worthwhile. Set gamma and gain to around 60%, brought brightness down to about 50% and backed saturation off to around 60-70%. That's the highest I've worked the gamma and gain. Seems to work quite nicely.
Well there you go, ya learn something new everyday. That sounds similar to the meade standard technique but with a twist. I hadn't heard about finding the spot where the rings are concentric first. I'll have to give that a go.
Nice image Matt, I was out last night as well, but the seeing around here was too poor. I'll be out again tonight though, see the 'HST + Amateurs' thread... Hopefully you can have another go as well.
Oh, you must be assuming my comment was a smart-A one Matt, it wasn't mate I assure you. (I'm thick as 2 pallets of bricks!) I just meant while were using curved mirrors, star centering is a must. I'm with Paul too....never heard of that technique you just described! I'll try anything!
Oh, I just remembered another benefit of doing it through the ToUcam. It's live eye. You don't have to look through an eyepiece and reach around the end of the scope to adjust. Simply position the laptop in the most convenient spot and watch the screen. Adjust collimation with one hand hand and adjust scope postition with the other to keep it centered on the screen. Very comfortable and civilized. You can even carry on a conversation and demonstrate at the same time. How geeky is that
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I see better 'quality' diffraction rings/central obstruction on the laptop than by eye threw an EP. Try it. (On a fairly bright star close to the intended target) You'll have to boost/tweak gain & gamma to get a good image.
I just meant while were using curved mirrors, star centering is a must. I'm with Paul too....never heard of that technique you just described! I'll try anything!
