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Delboy_Hog

First Jupiter pics with SPC900 and Mak 127

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Hi All,

Thought I'd share my first two attempts at Jupiter using the SPC900 (with Mak 127), taken in the early hours of Friday morning.

I am really quite proud of these, and if you want to know why, please click your way through my Jupiter journey, as by way of comparison, I've also attached my previous two best attempts, taken when Jupiter was at it's brightest some time back, using the good old "point a camera down the eyepiece" method.

Any newbies out there wondering how to take better photos of planets, my advice would be simple - webcams are the way forwards!

Thanks to all those on here who I've bugged for advice and tips. Without the help from SGL, I'd still be wondering why it looked like I'd taken a photo of a lightbulb in a dark room, and wondering how to improve!

So, the old, taken over a year ago:

post-23024-0-01335600-1344771222_thumb.j

post-23024-0-62808100-1344771045_thumb.j

And the new, about 50 seconds worth of AVI captured with Sharpcap (can't wait to see what difference is made by boosting that to several minutes of footage) stacked in Registax.

post-23024-0-20064000-1344771897_thumb.j

post-23024-0-96616300-1344771918_thumb.j

Any advice on how to improve would be very gratefully received.

Cheers,

Derek

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Looking good Derek! I assume those last 2 shots are without using a barlow? You've got good focus and colour so the next step would be more focal length with a 2 or 3x barlow.

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Thanks guys!

Stuart, you're right, these are without barlow - I did try a few rounds with the 2x barlow but didn't get the focus right so they didn't come out well. Can't wait to try the longer captures (as discussed in other threads!) and of the course, the 2x and 3x barlows!

Hopefully the next step in this journey will be a real stunner of a photo!

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(can't wait to see what difference is made by boosting that to several minutes of footage) stacked in Registax.

Nice shots, keeping the magnification small is the right thing to do at this time of year whilst Jupiter is still low. If you're after advice I wouldn't recommend shooting the planet for much longer than you did on these shots even when its at its best and highest in the sky. Several minutes of footage will simply blur all the detail on the planet as it rotates very fast. You want to aim for not much longer than a minute to a minute and a half tops.

Good luck

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Hi Mr S.

The SPC is a great bit of kit, isn't it. You seem to have pretty well nailed it with those shots - it's now the little tweaks:

Waiting for opposition - Jupiter will be a third bigger on the chip.

Waiting for good seeing... I had a good night on 7 December last year :rolleyes: I've noticed a big difference in seeing between being on the grass (better) compared to being on the patio area (worse).

Making sure your Mak is fully cooled and well collimated.

Using some sort of focus mask to help nail the focus, especially with a barlow.

Play with the wavelets on Registax (or photoshop :confused: )

If using a barlow, go for at least a 3 element barlow (revelation 2.5x or Orion Shorty-plus/Celestron Ultima) if not a 4 element powermate/Telextender. If you are on a budget then the revelation is excellent value.

And keep trying, but don't forget to just sit and have a look through an eyepiece occasionally :grin:

Adrian

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Very nice indeed... I've been considering a Mak 127 for planetary and now I've seen your result I'm quite encouraged to get one when SWMBO lets me :)

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Nice shots, keeping the magnification small is the right thing to do at this time of year whilst Jupiter is still low. If you're after advice I wouldn't recommend shooting the planet for much longer than you did on these shots even when its at its best and highest in the sky. Several minutes of footage will simply blur all the detail on the planet as it rotates very fast. You want to aim for not much longer than a minute to a minute and a half tops.

Good luck

I strongly disagree. Jupiter can be captured for 3-4 mins without blurring at up to 10 metres focal length. These shots are only 1.5 m fl so even 5 mins would probably be ok. Yes Jupiter is not at it's highest yet but is still 40 degrees before dawn so f 25-30 is quite easily done. When at opposition f 30-40 can be tried with good success.

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Because I wanted to understand what was actually going on I worked through all the maths here:

http://www.tanstaafl.co.uk/2012/03/focal-ratio-capture-length-planetary-imaging/

but the theoretical maximum capture length I worked out for Jupiter, for an SPC900 (or another camera with the same pixel size) as 130 seconds divided by the focal length in metres. That is the theoretical maximum though and is based on certain assumptions of how much potential blurring in detail you'd be prepared to accept (almost none in that case). It's also based on Jupiter being at its maximum apparent size, which it isn't right now.

As Stuart suggests, I think you can push that figure a fair bit before you start to notice significant image degradation. I wouldn't be so keen to do so if I were doing LRGB images in outstanding seeing with, say, the C9.25, but with the SPC900 and 127 Mak on most nights in the UK you can be a fair bit more relaxed.

James

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I'm not going to weigh into this ATM except to say that practical experience supportts the use of much longer captures than theory might suggest ??

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I'm not going to weigh into this ATM except to say that practical experience supportts the use of much longer captures than theory might suggest ??

I won't disagree at all, Rob. Those calculations are based on having perfect seeing and wanting no more than half a pixel of blurring due to rotation at the equator when the planet is at its largest apparent size, using an SPC900. When you consider that Jupiter varies in apparent size by almost a factor of two, and that in general seeing is not going to be that good that half a pixel rotation is a sensible target then there's a lot more time to play with.

I worked through the maths because the capture times are usually given without justification and I wanted to understand why they should be what they are and if I was being told the right thing. Once that made sense it was also obvious why, in the real world, that the upper limit could be considerably higher.

James

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I strongly disagree. Jupiter can be captured for 3-4 mins without blurring at up to 10 metres focal length. These shots are only 1.5 m fl so even 5 mins would probably be ok. Yes Jupiter is not at it's highest yet but is still 40 degrees before dawn so f 25-30 is quite easily done. When at opposition f 30-40 can be tried with good success.

To each their own. I agree that at this focal length its not such a major issue, but certainly if you were to film jupiter for 'several minutes' as the OP said he wanted to do, detail on the planet would blur from the rotation and smaller details such as barges and cloud patterns would suffer in your end result compared to a 90 second capture that would not pick up any rotation. My own personal practical experience has shown this to me, but I can't speak for others.

The only contention really is that you'd need to be shooting with a significant FL on the planet to produce an image large enough where you would really notice (or be bothered by) the lesser detail you'd end up with in the small features on the surface. Its also something that you become more bothered about the deeper you go into planetary imaging as you strive for better, sharper and more accurate shots of the surface details of Jupiter.

Edited by Bubble and Squeak

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I'd be very interested to see your 90 sec capture images.

I'm not arguing with the theory but in practice that length of avi is way too noisy for any significant processing. You end up trying to reduce the noise rather than enhance the detail. As I mentioned unless one is shooting at over 10 metres fl (well over) the 90 sec rule does not work in reality.

Don't quote me on this but I'm pretty sure the stacking and aligning process of Registax or AS!2 corrects a certain amount of rotation though not like winjupas which allows for over 6 min captures (Think Damian Peach has done 8 mins?).

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I'm not arguing with the theory but in practice that length of avi is way too noisy for any significant processing. You end up trying to reduce the noise rather than enhance the detail.

Thats certainly true. Noise has never bothered me as much as the possibility of losing detail to rotation but you know what.., I may give it a try at longer times. You've got my curiosity going. I feel an experimental 2012-13 Jupiter apparition coming on!

Edited by Bubble and Squeak

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Surely stacking is about noise reduction? Then wavelets (and the like) is for detail enhancement? In a pure stacking function I'd have thought rotation would degrade the final image rather than add to it (or the rotated frames might get thrown out completely depending on what averaging method is in use), but that doesn't mean Registax doesn't do something else to handle the rotated images.

James

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Yes stacking reduces noise but if you've only a few frames to play with as soon as wavelets are introduced back comes the noise and then you need to use noise reduction which softens (blurs) the image slightly so you loose the detail.

If I wanted to image with a spc900 webcam at 10fps for 90 secs I've only got 900 frames. Unless seeing is very good there will be only 2-300 decent frames for stacking. This does not allow for much sharpening without noise kicking in. Obviously it depends in the camera settings. If gain is very low then you can get away with fewer frames but if you want to maximise the focal length of your given scope then gain is usually reasonably high.

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Ive had better results with 4 min runs than 2 mins, 2400 frames than with 1200 on jupe with my spc 900, all i can say is the limit is more than the general golden rule thats banded about, which is my own personal view! not necessarily the right one.

Edited by si@nite

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Interesting stuff! Thank you all! Worth having a play around with the capture lengths - some experimentation required it seems.

James, your maths / physics blew me away a bit, but it makes for fascinating reading. :icon_salut: Interesting to see the differences in capture times your conclusions draw for the other planets too, as they're all on my hit list now I feel a bit more comfortable with the kit.

RogerTheDodger - I confess I had to look up SWMBO, but grinned when I found out what it was! :grin: This is my only scope, so I cannot compare with other scopes, but this one has been brilliant for planetary for me, certainly with visual and increasingly with photography as well, once you've read a few dozen of the forums on here! <I particularly recommend the "embarrasing Jupiters webcam clinic">

Other members on here have taken incredible shots of Venus, Mars and Saturn too, with this set up, so I'm looking foward to having a go at those as well. All a bit tricky to get at at the moment, though Venus is do-able, providing that you're not hoping for a productive day at work after the necessary early start! :coffee:

And Mr T! Fancy meeting you here! Took me a moment to figure out who you were! Wouldn't mind a shot of Jupiter like your profile pic there sir. :icon_salut: The advice is much appreciated - I still have much to learn. Very much looking forward to opposition, and hoping there'll be one of those magic nights with good seeing around then too. With the amount of cloud and rain we've had up North here (think I'm averaging about one good night a month in 2012 so far) I'd settle for a few nights of average seeing for now! Fingers crossed though eh?

Thanks to all for taking a peek at my Jupiter journey! :cool:

Derek

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