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Jupiter Nov 14th 1st light Flextube auto 250


Space Cowboy
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Thanks guys! Yes i'm now in the heavyweight division lol Certainly a contrast to the skymax 127.

This image is actually overexposed (had to reduce brightness) even though I used 1/50 shutter speed. Did do some at 1/100 but they were undercooked plus the clouds were spoiling the fun.

Once I've got used to the extra light intake of the 10" compared to 5" i'm hoping to get some good results especially with Saturn (licking lips).

Hopefully if I move up to f20 overexposure wont to such an issue with Jupiter (scared to go below 50% gain i.e onion rings)

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Early days yet but visually Jupiter and the Moon are certainly superior. With the Skymax Jupiter has a yellow hue but through the Dob its a more natural colour and shows clearer banding. The moon is awesome....takes much higher magnification. I was using 650x on crators with the same clarity as half that on the skymax.

I'm hoping to get superior images too so long as the tracking can cope with longer focal length. There was a lot of drifting at 3x Barlow and I was keeping the handcontrol pressed during the full avi. With the scope properly level fingers crossed tracking will improve. Quite impressed by the smoothness of slewing for such a large beast.

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Hopefully if I move up to f20 overexposure wont to such an issue with Jupiter (scared to go below 50% gain i.e onion rings)

Not too bad Stuart.

Don't be scared to experiment with gain and other different settings :)

You have nothing to lose and lots to gain:rolleyes: (sorry, bad pun):)

Are you using a capture program that has a histogram display for each channel? I find this very useful to set correct exposure:icon_salut:

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Not too bad Stuart.

Don't be scared to experiment with gain and other different settings :)

You have nothing to lose and lots to gain:rolleyes: (sorry, bad pun):)

Are you using a capture program that has a histogram display for each channel? I find this very useful to set correct exposure:icon_salut:

Thanks Clayton,

Its easier to experiment when you have a clear sky with no clouds threatening lol On this occasion i knew there was only about 5-10 mins before wipeout. I'm using Craterlet rather than vxastrocapture (which has a histogram but will not run at more than 8fps and produces poorer luminance).

Thanks brantuk!

The settings were 1/50 shutter, 0 Gamma and 56 Gain using Craterlet.

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Thanks Clayton,

Its easier to experiment when you have a clear sky with no clouds threatening lol On this occasion i knew there was only about 5-10 mins before wipeout. I'm using Craterlet rather than vxastrocapture (which has a histogram but will not run at more than 8fps and produces poorer luminance).

Thanks brantuk!

The settings were 1/50 shutter, 0 Gamma and 56 Gain using Craterlet.

Yes I know what you mean re the clouds:eek::p

I use wxAstrocapture to set the histogram and then switch to my normal program (QCFocus) to capture as wx produces a white ring around Jupiter, which I could process out :) but can't be bothered :)

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Yes I know what you mean re the clouds:eek::D

I use wxAstrocapture to set the histogram and then switch to my normal program (QCFocus) to capture as wx produces a white ring around Jupiter, which I could process out :) but can't be bothered ;)

I could do the same if astrocapture would run at the same frame rate....I've asked on here before but nobody seems to know why it wont. All other capture programs I've tried are no problem.

Cheers Ezza! I'm gonna set up a large paving slab in the middle of the garden. Should keep things level and out of the wet grass. I did read somewhere that the auto track handset worked better than the GOTO handset for tracking so will try that out too. With everything properly set up I'm hoping for 4, 5 or 6x Barlow scale.

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This image was at 1/100 shutter :

An excellent image (the colours are beatifully saturated and you can see very butle hue differences, and you haven't processed it all out); I think the focus is the next thing to optimise is probably the focus (as it's very hard to do correctly on an f/5).

Have you considered using a Bahtinov mask and a star to focus?

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Thanks Sixela!

You are dead right about focus. I'd been looking at the moon, saw cloud had cleared Jupiter and slewed across...thought focus looked near enough and took the images in that clear window. Usually use Jups moons for focus (will look into mask option).

The other point I've not mentioned was collimation. Using a laser I had no problem aligning the primary but could not get the secondary 100% nailed...laser was within primary bullseye but not dead central, Not sure how much difference that makes?

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For planetary imaging adjusting the tilt of the secondary correctly isn't critical at all, provided it doesn't affect the correctness of the adjusting of the primary afterwards.

If you're using the return beam of a laser collimator, you should know that the return beam is only a correct reference when the forward beam points exactly at the middle of the primary. Otherwise, you'll miscollimate the optical axis at the focal plane by half the error in pointing the forward beam (because all the beams that trace back to themselves go through the centre of curvature of te mirror, but not necessarily the focal point).

That's why the barlowed laser protocol was devised by Nils Olof Carlin. If you really want to continue using the laser to set the tilt of the primary, I'd suggest buying a Howie Glatter TuBlug to put your laser in (unless you already have a barlow and want to build a screen to use the barlowed laser protocol yourself - all you want is a cap that can go over the barlow, not transparent and preferably white, with a small hole for the forward beam. On the screen you read the shadow of the centre spot in the returning light cylinder and make that centred).

If you don't want to go that route, always check the collimation with a collimation cap or Cheshire with the pupil close to the focal plane. It's as precise as the barlowed laser, and more precise than the unbarlowed laser's return beam.

The absolute best Cheshire for this is the CatsEye BlackCat cheshire and matching centre spot, but you don't have to buy it if you're satisfied with the tools you have now. Even the small collimation cap eith reflective inside that came with my Orion scope will do (although some don't have a very well centred pupil, and obviously that's not good).

Also, check whether the centre spot on your mirror is actually at the centre, or at least how much the error is. More than 1mm is Not Good.

CatsEye collimation's template for the centre spot they sell with the BlackCat will let you centre spot with ease, but it's not the only way to check it (some tracing paper and a compass will also do).

What people in my neck of the woods usually do is borrow my CatsEye template (I even have some spare centre spots to place on their mirrors if they want me to correct the error --I've done it around 30 times by now so I'm less nervous than some), so if you can find someone in your 'hood with CatsEye tools I'd certainly try to borrow that template.

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thought focus looked near enough

If you were just "looking" at the moon before (and then at Jupiter) through an eyepiece, it's treacherous.

The eye is actually fairly good at focusing on objects closer than infinity (fortunately) and will accommodate for quite large focus differences, but a camera sensor will not; so if it looks focused to the eye, it may not be focused for a camera sensor.

It's pretty important to evaluate focus with the camera/webcam. Preferably with a star, and possibly with a Hartmann mask or its successor the Bahtinov mask.

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When I said "looking" at the moon I meant through the webcam :)

OK; sorry about the confusion. But it is a lot easier to see whether focus is OK with a point source and a Bahtinov mask. The trouble is that often, it's only once the subs are stacked and processes that you'll see how good focus was, and by then it's too late to do much about it (even though wavelet processing can actually partly repair small focus errors).

Edited by sixela
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