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Old 31-07-2020, 08:57 PM
Quopaz (Nick)
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Jupiters

So much video to go through after 3 nights of very good seeing. Have made a start, one with the red spot and the other with Europa and shadow from tonight about an hour ago:
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Old 06-08-2020, 08:27 PM
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Good image Nick
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Old 07-08-2020, 09:45 AM
Spidy (Phil)
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I'm curious. I've had my telescope home since last Friday and the only clear night we had in Melbourne was Saturday night, which I couldn't use because of prior engagements (i.e the missus).


So, I'm still to see first light with it. My question is, those images you posted Nick, are they actual size, that is, is that what you see in Sharpcap or Firecapture or AutoStakkert!2 or whatever it is you use?


I have a 23mm, 8.8mm eyepieces and an ASI017 and ASI174 MM mini cameras, so I'm guessing for planetary, I use the 8.8mm eyepiece and the 174 mono camera for capture?


Some details of how you captured those awesome images would be great Nick.
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Old 07-08-2020, 12:54 PM
Quopaz (Nick)
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Hi Phil, my scope is a 10" Skywatcher at about F 4.8. I use a 3x barlow to give about F 14.4, I don't use any eyepieces. I use a Canon 60D DSLR in the 640x480 crop mode. I don't use sharpcap or firecapture, just straight onto the camera then transfer the videos to my computer. For jupiter I set the crop function in PIPP to 300, saturn and mars 250. The rest is just how it comes out after going through autostakkert and registax. Once finished I sometimes do further cropping in Paint if needed.

On the camera screen, jupiter looks about as big as a 5c coin, taking up about half the height of the screen. If it drifts a bit I use the arrow keys to keep it on screen. When filming, I like to be able to see on the camera the thin gap between the red spot and the cloud band, detail in the festoons, and the small round circles but needs to be good seeing conditions. Processing brings out more details than I can see at the camera.
From what I've read, you should film at about F20 to F 30, but I'm getting best results at F 14.4 with the 3x barlow. However, I'm not sure if that takes into account the crop mode magnification on the camera. I've tried with a 2x barlow and with two 2x barlows stacked (4x) but 3x has been best. I'd like to try a 3.5x barlow but I don't know if they make them.
Anyway, that's pretty much how I'm doing it at the moment and that may change if I find a better way. Here's a pic from a few nights ago that I didn't crop in PIPP, so that I could fit the moons in. I later cropped it a bit in Paint around the moons. Moons are Io and Ganymede:
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Old 07-08-2020, 02:11 PM
Spidy (Phil)
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Thanks for the detailed response Nick.


Can't wait to start my own journey.
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Old 07-08-2020, 04:43 PM
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Quote:
Originally Posted by Spidy View Post
I'm curious. I've had my telescope home since last Friday and the only clear night we had in Melbourne was Saturday night, which I couldn't use because of prior engagements (i.e the missus).


So, I'm still to see first light with it. My question is, those images you posted Nick, are they actual size, that is, is that what you see in Sharpcap or Firecapture or AutoStakkert!2 or whatever it is you use?


I have a 23mm, 8.8mm eyepieces and an ASI017 and ASI174 MM mini cameras, so I'm guessing for planetary, I use the 8.8mm eyepiece and the 174 mono camera for capture?


Some details of how you captured those awesome images would be great Nick.
Hi Phil, welcome to the rabbit hole

As Nick says (nice images by the way ), no eyepiece required, just connect your favourite camera (I'd start with the colour camera myself) to the end of the OTA (with a Barlow if you have it) and away you go. Not sure what equipment you have, but the best way to capture the planets is to track them for a few minutes at a time, capturing video frames as fast as you can (within reason of course) using something FireCapture (my personal favourite), stack them in AS!3, sharpen them in Registax, post process in Photoshop (or your favourite editing software) and away you go.

For best results, you should try to capture at a focal length around 5x the pixel size of your camera in pixels, so for your ASI071MC you should aim for f/24 with your Barlow. Capture Jupiter for 3 minutes, Saturn and Mars for 5, and aim for 100+fps. This should give you a good set of frames to choose from when stacking.

According to my weather apps, it looks like the next best time for imaging in Melbourne is Monday night (although we may get a chance on Sunday also), so lots of time to brush up on your technique

Watch these videos, they will help a lot.
http://planetaryimagingtutorials.com/

Andrew

P.S. Last time I got out there, I was able to bag a few myself, this is the best time to be imaging the planets!@
http://www.iceinspace.com.au/forum/s...d.php?t=184973
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Old 07-08-2020, 07:20 PM
Quopaz (Nick)
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Hi Andrew, using that formula of 5x (the video says even up to 6x or 7x) the pixel size for the 60D I get: 5x 4.3= f 21.5. With the natural focal length of 4.8, I should need a 4.5x barlow to acheive this. Why then am I getting better results with a 3x barlow than 4x (two 2x barlows joined)? Something to do with the magnification factor in movie crop mode? Or would a proper 4x barlow or powermate be better than joining two 2x barlows together?
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Old 07-08-2020, 10:42 PM
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Quote:
Originally Posted by Quopaz View Post
Hi Andrew, using that formula of 5x (the video says even up to 6x or 7x) the pixel size for the 60D I get: 5x 4.3= f 21.5. With the natural focal length of 4.8, I should need a 4.5x barlow to acheive this. Why then am I getting better results with a 3x barlow than 4x (two 2x barlows joined)? Something to do with the magnification factor in movie crop mode? Or would a proper 4x barlow or powermate be better than joining two 2x barlows together?
Firstly, are you sure you are getting 3x magnification from your 3x Barlow? Nearly all Barlows change their magnification with distance from the back of the Barlow (for instance, the graph on this page).
http://www.televue.com/engine/TV3b_p...=52&Tab=_photo

You can tell what focal length you are actually using by using the formula shown in the image below (from here), simply measure the size of Jupiter's width in pixels (with the planet horizontal), type in the pixel size and the size of the planet in arcsec and you can work out the actual focal length you are capturing at. You might be closer than you think. When I was using my Canon DSLR and Celestron 2x Barlow, my effective magnification turned out to be 2.6x. A quick back of the envelope calculation from your images above shows you are capturing at about f/19 with your current setup, or about 4.4x the pixel size (which is pretty much bang on).

That being said, using just 1 Barlow would be far preferred over stacking two together.

Andrew
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Old 08-08-2020, 10:43 AM
Quopaz (Nick)
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Thanks Andrew, yeah that's probably what it would be. I'm probably getting more than 3x magnification from my 3x barlow. Maybe if I didn't slide it all the way in I could even get a little bit more magnification?
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Old 08-08-2020, 12:14 PM
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Yep, that would work too. I don't think it would make that much difference though, but you might want to try ...
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Old 09-08-2020, 11:24 AM
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Just playing around with my gear and discovered that my 3x barlow fits into my variable length eyepiece projection adapter. Meaning I can extend the distance between the camera and barlow by up to 40mm. Would have to make a difference? I haven't been using the eyepiece projection method lately, just using the 3x barlow. Eyepiece projection worked with the 25mm eyepiece in the 600D, but not in the 60D- image was too big, would need a different eyepiece for the 60D, something like 30-40mm. I tend to use trial and error to figure things out, but there are probably ways of working it out so you don't have to waste money on things that don't work.
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Old 09-08-2020, 07:52 PM
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Yep, that would work. You can use the formula mentioned above to work out what f/number you are actually capturing at, the problem is that seeing changes hourly (even minutely) so it's difficult to say whether one setting gives you better results based on the images you get. Aim for f/21, but don't fixate on it too much, the maths is only approximate anyway (see image below for the "proof").

I'm not a fan of eyepiece projection, I reckon the less glass you have in the system, the better. However, I've never tried it before.

Andrew
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Old 10-08-2020, 12:10 PM
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Thanks again Andrew. So in theory a 4x barlow would give me f/19.2 which would be close. Maybe even a 5x at f/24. Just had a look and couldn't find any 4x barlows but there was a 4x powermate, bit more expensive and it was 2" not 1.25"- might be worth a try? Strange that stacking two 2x barlows didn't work as well as the 3x, but like you said earlier what I'm actually getting might be more than 4x with that set up. There was also a cheaper 5x barlow I could try too, and a 5x powermate.
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Old 10-08-2020, 03:34 PM
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Before you spend any money on an expensive 4x Barlow/PowerMate, I would try the 3x with the extender and see what magnification you end up with. I suspect you should be able to get pretty close to 4x with what you currently have. Have you measured the magnification of your 2x2x barlow combination? I suspect it will be far greater than 4x. Having too high a magnification will reduce the brightness of the planet, and reduce the signal to noise ratio.
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Old 11-08-2020, 11:35 AM
Quopaz (Nick)
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No, I haven't worked out the actual magnification yet, I need to know how to measure the size of jupiter's width in pixels. My guess would be if I'm using the 640x480 crop mode, then the width of the screen would be 640 pixels, and I could measure the size of jupiter and work it out as a percentage of that? But that might not be right, and there might be a better way to do it. Size of planet in arcsec I should be able to look up.

I also found another way to get an extension in there. I unscrewed the lens out of a 2x barlow, leaving the hollow tube, and the 3x barlow fits onto that nicely. I think this would get me pretty close to where it needs to be.
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Old 11-08-2020, 12:29 PM
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Did a bit of googling and found I can use Winjupos to measure pixel size, and it also gives planet size in arc sec, much easier! For my current set up with the 3x barlow, FL worked out to be 4945. Focal Ratio worked out to be 19.7, (not 14.4 like I thought) meaning my 3x barlow is actually working like a 4.1x barlow. Probably why it has been giving the best results. Now I need to work out what the two 2x barlows stacked were actually giving.
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Old 11-08-2020, 01:05 PM
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Doing the same for the two 2x barlows stacked, I came up with a focal length of 8123.8, giving a focal ratio of 32.5 (not 19.2 like it should be). Meaning the two 2x barlows stacked are actually working like a 6.7x barlow, not 4x. Probably why it hasn't been working very well! All starting to make sense now. The 3x barlow with an extender tube should be close to optimal, even as it was at f/19.7 is probably not too bad but a little bit more might be better.
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Old 11-08-2020, 04:32 PM
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Yep, as suspected your Barlows are giving you a higher magnification than what's written on the box. I myself use SkySafari Plus to show me what's happening in the sky, it also gives the size of the planets in arcsec which is what I used to estimate your effective f/num of around f/19 from the equation above. All you need to do is measure the number of pixels across the equator (and yes, just use a photo editor to count them) and apply the formula.

I'm surprised you got anything with the 2 Barlows in series like that, working with an 8m telescope would not have been easy!

Glad you were able to work it all out, at least now you have confidence in your equipment.

Andrew
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