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saturn 24th May


neil phillips
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Was just experimenting with the now going saturn. i recently got a 5x TV powermate, and just for fun thought i would see what sizes popped up. What most people dont realize is the 5x powermate is 5x visual. for ccd work its actually 7.7x so these shots were take at F48

and over 12.000 mm focal length. way over the top agreed. i was surprised i snatched what almost is a workable result. seeing wasnt really up to it. and the camera and scope not sensetive enough at these crazy powers. But i reckon under good seeing and a 618 ccd clearly this ampliyfier is nice. As it seems to want to deliver even under average seeing and not enough sensetivety.

I also took a image of my optics with the DMK to see what collimation looked like. it looks fairly good. but there is a fuzzy side,

Im not sure ? i think its temperature related, as the rings themselves look even. im not positive though. any thoughts or opinions if others think im right and this is a temperature, not collimation effect.

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will have to redo this, as i didnt align the rings with a large enough box but im in a rush.

i prefer this one its a higher frame rate than top image. 30 fps 1/30th secs exposure. 120% k3 ccd

5759188150_898f615aa8_o.png

Edited by neil phillips
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Impressive images Neil!

I'm getting 6x (f30) with my powermate but both sessions I've tried it out (one last night) seeing has been pants.

I bet you are champing at the bit for Jupiter now! Just imagine Jup at f48 and 50 degrees! BTW do you use a B mask? I used one for first time last night on Arcturus but it was not as clear cut to focus as I expected using live view.

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Hi Rik im not sure where up was ? but it does look like currents doesnt it.

No mask Stuart. good old fashioned tweaking. I used a OC1 motor focusser. found myself going back to hand. I dont know. too many years, being connected to the scope during focusing. seems alien any other way. But i wish i could get the hang of a motor. Do you rate the mask. for very precise focus, lets say at these powers ?

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Hi Rik im not sure where up was ? but it does look like currents doesnt it.

No mask Stuart. good old fashioned tweaking. I used a OC1 motor focusser. found myself going back to hand. I dont know. too many years, being connected to the scope during focusing. seems alien any other way. But i wish i could get the hang of a motor. Do you rate the mask. for very precise focus, lets say at these powers ?

I was a little disappointed the defraction spikes were not as clear and precise as I'd hoped and with seeing being unstable there was a certain amount of guess work. I'm not one that likes to fiddle about too much so may end up going back to manual tweaking on the planet. Having the dew shield off the scope while using the mask is a worry..not much point of having perfect focus if the optics mist up! Anyhow I will try it out again when seeing is better.

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That's seriously impressive Neil !

As for the rings/collimation- the rings look nicely even and concentric, the fuzziness is not down to collimation I'd bank on it ! More likely residual heat and seeing effects.

Early August mornings aren't that far away :D and certainly by the end of August I'll be up bright 'n early :p

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Great to try limits and in perfect seeing this would be doable even with fewer frames. Nice to see diff rings and fuzz at lower part looks strange - successive nights may show it as tube effect of cool down or something. Should focus and stack to see Airy disc which is a better test but seeing is often distructive with this feature.

John.

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Hi Neil - DR's almost never look the same from one set of seeing conditions to the next.....I think it's important to make sure that the scope is as close to ambient temperature as possible to get the best appraisal of collimation, as temperature effects can be quite overwhelming in terms of their distortion effects upon the Fresnel/diffraction rings.

It is also much better when tweaking collimation (and I do, and advise anyone else, to do it every time before they image) to make a short avi (say 200-odd frames) in the red channel and then a quick Registax processing.....this will give you a much more accurate idea of the concentricity of the rings, and in particular the poisson point, that small dot of light right in the middle of that central "dark zone."

It is when the pp is exactly central there that the rings will be truly concentric and your scope accurately collimated - this is for an SCT or a newtonian where there is no offset for the secondary.....as most newts these days have a slight offset you would expect a slight displacement of the pp to one side of centre in the dark zone...and a commensurate shift re concentricity in the rings.....

I now allways run these little captures and processings as they take hardly any time, and ensure that whatever the seeing you can be confident that you've collimated the scope as best as can be - much easier and more accurately gauging the exact nature of the patterns.....I believe the "Metaguide" software program allows you to do similar "on the fly" but I'm more than happy to take the little bit of extra time as said with Reggie.....:p

Airy disks (at focus) are something I just never see in the C11, but a truly concentric set of DR's for the SCT are just as good imho.:D

I've looked through my files and managed to find 2 examples I haven't binned of jpegs I've kept of DR's from samplings when collimating to use as an example here.....neither of these appear terribly similar nor are they "perfect" - the pp's (poisson points) are both displaced slightly to the left of dead centre, and if you look carefully you'll see there's a corresponding effect on the spacing between the rings that is different on each side: as it's from my C11 it means slightly off from truly collimated optics - but for an offset newt they'd have been just about dead on the money....!;)

post-16205-133877609255_thumb.jpg

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Cheers Clayton

Will have to try that John. Thats all interesting information Darryl. thanks for posting the examples. I think it will be worth getting the TV adapter that will enable me to remove the long barrel and directly connect the power mate to the webcam. for a more realistic focal length for good seeing. but its all worth trying and experimenting and i certainly will. Bird uses hes TV 5x with hes Newts at 7.7x. though of course hes conditions are for the most part superiour. But its going to be a exciting time in the coming months. Jupiter has entered the morning. Early days though. not going to try just yet. still to low. i need that CCD chaps. i may gey the astronomiser mod in july. and wait and see if the IS camera is any good later in the summer. still undecided. Especially as the flea is already waiting. If i could get the readys

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i need that CCD chaps.

hehe :p

I'm looking also on few cams (as Basler tends to be naughty from time to time). First is French cam - iNova PLA-Mx

Astronomie - une SATURNE du 18 mai pour changer ! - AstroSurf

Astronomie - saturne du 17, ma plus belle !!! - AstroSurf

Astronomie - Deux saturnes du 7/04 a la PLA-Mx - AstroSurf

[Planète] Saturne à 10m ... - Forums d'astronomie Webastro

whis is known only in France I guess. The constructor (?) of those cameras (Roger Perié / M42 Optic) did state that the cam uses lower clock rates in the CCD to prevent any artifacts like in DMK 60 FPS or sometimes Basler. ~399 EUR for the camera in some French shops. And there is cooled QHY IMG0H - but that needs a little more in depth reviews/check to be sure if that QHY actually works as intended :D

From my experiments there is no strong point in doing 140 FPS luminance on Saturn at max gain, f/20 and 5 msec exposures... Exposures up to 25-30ms and gain as low as those exposures allow (+ seeing) tend to give higher quality / less noise after processing.

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Thanks for the links Rik. very interesting. the second large saturn shot on the last link. looks iffy though as i can see a artifact on the left hand side of the planet. plus under the rings. I have the rings artifact a bit. but not the planet. It could be seeing, but im unsure ?

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5xpkc9.jpg

That's ~f/37 so it's overscaled a bit. It looks like it could be a diffraction pattern or uneven stack or something else... If it doesn't cross the planet and doesn't screw the image it's rather ok.

I have that shadow too, and it's also C11 (maybe it's SCT related?):

1qlum-2b-rgb-1959.png

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Hi Neil - DR's almost never look the same from one set of seeing conditions to the next.....I think it's important to make sure that the scope is as close to ambient temperature as possible to get the best appraisal of collimation, as temperature effects can be quite overwhelming in terms of their distortion effects upon the Fresnel/diffraction rings.

It is also much better when tweaking collimation (and I do, and advise anyone else, to do it every time before they image) to make a short avi (say 200-odd frames) in the red channel and then a quick Registax processing.....this will give you a much more accurate idea of the concentricity of the rings, and in particular the poisson point, that small dot of light right in the middle of that central "dark zone."

It is when the pp is exactly central there that the rings will be truly concentric and your scope accurately collimated - this is for an SCT or a newtonian where there is no offset for the secondary.....as most newts these days have a slight offset you would expect a slight displacement of the pp to one side of centre in the dark zone...and a commensurate shift re concentricity in the rings.....

I now allways run these little captures and processings as they take hardly any time, and ensure that whatever the seeing you can be confident that you've collimated the scope as best as can be - much easier and more accurately gauging the exact nature of the patterns.....I believe the "Metaguide" software program allows you to do similar "on the fly" but I'm more than happy to take the little bit of extra time as said with Reggie.....:D

Airy disks (at focus) are something I just never see in the C11, but a truly concentric set of DR's for the SCT are just as good imho.;)

I've looked through my files and managed to find 2 examples I haven't binned of jpegs I've kept of DR's from samplings when collimating to use as an example here.....neither of these appear terribly similar nor are they "perfect" - the pp's (poisson points) are both displaced slightly to the left of dead centre, and if you look carefully you'll see there's a corresponding effect on the spacing between the rings that is different on each side: as it's from my C11 it means slightly off from truly collimated optics - but for an offset newt they'd have been just about dead on the money....!:D

:D Most of this good advice I agree with 100% Darryl, but I'm not so sure about the part's I have highlighted :D

In my limited understanding of DR's and PP's the Newtonians secondary's centrality plays no part in the resulting image of DR's and PP's as long as all the elements are collimated re the light path. Being perfecly flat (in an ideal world) the secondary in theory doesn't even have to be at 45 degrees as long as the light path travels smack bang up the centre of the focuser which would also have to be tilted in this case, however it is much easier to achieve good collimation with orthoganal elements. :p;)

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