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Jim Chung
Vendor - Icodome
*****

Reged: 12/07/05

Loc: Toronto
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5545381 - 11/29/12 11:43 AM

Tim,

I've done several ISS transits of the Moon & Sun and I would advise on a wider field because you might miss is entirely otherwise. You must be exactly on the Calsky centerline and then sometimes they are still a little off. This past summer I was prepared to image the ISS at about 2000mm focal length with my 2/3" sensored Point Grey Research camera but decided to hedge me bets and image at only 1000 mm. It was the right decision because even though I was exactly on the centerline the ISS transited the Sun at a very slightly lower level and I would have missed it at the high focal length/FOV.

Getting the right exposure will be tricky since the ISS can be quite bright and is easy to overexpose and thus lose detail. It's easier to capture a Lunar or Solar transit because both those bodies will always be brighter and exposing them correctly will always ensure a sharp silhouette capture of the ISS.

If you're using the 640x480 Flea then I would use a much shorter focal length instrument because even if you are lucky to get it, the speed of the ISS will only allow it to appear in one frame.

With DSLR .... I'd still hedge my bets and get a focal reducer on the C14 or the 10" - and have both cameras running a couple of minutes before predicted time although you have the advantage of actually seeing the ISS in the sky with the naked eye well before it crosses Capella.


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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: Jim Chung]
      #5545496 - 11/29/12 12:56 PM

Hey Jim,

Thanks for the advice. Yes, I've considered all those possibilities. I figure the ISS will be in the FOV of the Flea3 for about 0.3 seconds and I was going to run it at 100 -120 FPS hoping for the ISS to show in a few frames.

I do have a focal reducer for both telescopes as well as a thread in 0.5 reducer for the Flea3. I'm going to set up tonight so I might see what kinds of images I can get with the reducers stacked. I think I'll take your advice and put the 0.6 on the C14 along with the T2i. (I'll have to get out my chainsaw first).

Focus won't be an issue with Capella right in the FOV... but exposure will. I was going to use the Moon as a guide there and hope for the best. It will be tricky but I don't have any other choice. At least, I haven't thought of any.

I'd love to do a transit. But they don't seem to happen very often. At least from my location.

I'm open to any and all suggestions at this point so please feel free...


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FoxK
Carpal Tunnel
*****

Reged: 11/07/07

Loc: Cape Cod, MA
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5545640 - 11/29/12 02:29 PM

I'd go an entirely different route. Although its ok to use Capella as a guide to get a perfect focus (which is essential), I wouldn't use it as the only aimpoint for getting frames of the ISS. I went through all this years ago and found the best method is to precisely match your finder with what is on the camera, ie, image capella, then move the finder so that whatever the finder is pointing at, the camera is imaging. I actually went out and bought a good 50mm crosshair illuminated finder for this........when I move the crosshairs onto the ISS, I know I have a really good chance of having a few frames at least, of the ISS...usually I have a few HUNDRED to choose from....so many that I can use registax to process a few frames in a row to get a better image. If you have a good open field view of the West, then you can start imaging very early in the transit. This way you have more room for error and in my opinion, its inevitable that the first few tries produce not so great results but are useful in that you can get a good idea of the correct exposure based on this result. If you use the crosshair method, you can start imaging early in the transit when it is less bright, up until it is overhead and beyond, where it is VERY bright....the point being that you will be imaging the ISS though a variety of brightnesses so hopefully some will be correct exposure.




If you focus and aim right at Capella, then there's no room for error. Any computer hiccup and you'll miss it. With that F/L you prolly get less than 10 frames but Its ok if you wanna try this way though.....its less work trying to keep the ISS in the crosshairs but I NEVER go that route anymore and using the crosshair method, I now get a 100% success rate (due to knowing the EXACT correct exposure per given overflight brightness. It took a few tries to get it down pat however. Oh, and because you don't want blurring, you're gonna want at least 1/1000 shutterspeed. I use an 80mm ED refractor with a 2x barlow....1/1200 exp and gain about 3/5 to full is about the right settings in my case and might be a good guide for you.




Good luck!


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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: FoxK]
      #5546765 - 11/30/12 08:06 AM Attachment (9 downloads)

Well when I checked this morning, CalSky had changed it's mind to "close to" Capella. So, in spite of Murphy stopping by (drive issues, focus, forgetting to lock the mirror, and FOG!) I decided to try a manual grab... Take my word for it... this is the ISS... though you'd never know it to look at it.

I have two more passes I can try, but it doesn't look like the weather will cooperate. Oh well... maybe next time.

Still... it was an experience.

Stats: Flea3 + 0.5X reducer, 10"LX200GPS,manually pointed 15 frame stack


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Koen Dierckens
professor emeritus


Reged: 11/04/09

Loc: Antwerp, Belgium
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5546787 - 11/30/12 08:33 AM

Murphy always is right behind you, of course, but I think you did a good job.
Following such fast objects with long focal length and the need for manually tweaking parameters like exposure and focus just is damn hard and need practice.

I practiced already a few times photographing passenger jets cruising at 30,000 feet. With them, you have the advantage that when you loose them out of sight, you can use the contrail to lead you back to the plane. (also manipulating camera and telescope in daytime is way easier) But because they are closer, you continuously need to adapt focus as the planes fly over. These sessions made me aware of the challenges when imaging satellites.

I guess that your experience triggered a new interest anyways and I'm sure the next times will give better results. Thanks for sharing your little adventure!


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Mike Phillips
Post Laureate
*****

Reged: 02/21/06

Loc: Swift Creek, NC - 35.682 N, 78...
Re: ISS and Capella photo op planning new [Re: Koen Dierckens]
      #5546845 - 11/30/12 09:21 AM

Great 1st try Tim!!! Glad you got something.

Mike


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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: Mike Phillips]
      #5546887 - 11/30/12 09:57 AM

Thanks guys.

Actually, other than the focus going off (not sure how that happened) I'm rather pleased with this as a first attempt. I learned quite a bit. The exposure time wasn't bad, so I have a handle on that now.

I'll double check collimation, and make sure to lock the mirror down tonight in the hopes that tomorrow morning will cooperate... though it isn't looking promising right now.

Thanks to everyone that contributed their technical and emotional assistance. It was a fun little adventure and definitely worth another try.

Cheers
Tim


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FoxK
Carpal Tunnel
*****

Reged: 11/07/07

Loc: Cape Cod, MA
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5547092 - 11/30/12 12:19 PM

Tim..don't give up yet........reload that series of frames in registax....checkmark the frames you want included (make sure the box for "Frame List" is checked) and try, instead of manual alignment, use the option for "align using Centre of gravity".other options you want checked are "track object" and "predict track"

I'm not convinced its even out of focus...bad stacking will result in an effect that can mimic bad focus. Perhaps you can load your video into registax and go through the frames and make an image of the best single frame. It appears to me that your image is just stacked poorly.....I believe I can see the radiators which tend to often be the brightest parts, and they appear pretty focused but multiple images of it (as expected by a bad stack)

Also, do yourself a favor....write down the brightness of that overflight and write down what you used here as far as shutter speed, and gain so you have a frame of reference for next time. We can get a better idea for adjustment after looking at the single best frame if possible....also....If I stop responding, I am leaving to go crab fishing in Alaska on Saturday so will be unable to help any further so hopefully we can get some results tonight.I will check later.


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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: FoxK]
      #5547181 - 11/30/12 01:03 PM

Hey Fox,

Thanks for the encouragement. Alas, I do think it is a focus issue... mixed with the thin fog I was shooting thru. I ran the avi thru VirtualDub and selected the frames that contained the ISS. It was out of focus in each frame. But maybe close? Anyway, the longest stretch I got was 16 frames, I ran that thru Castrator and then stacked with AS!2.

I have the record log from FireCapture so I know the camera settings. I don't plan to give up just yet. Not sure what I want to try differently for the next go (tomorrow morning at 5:34). I've never tried the satellite tracking feature of the LX200GPS. Don't know how well that works. I had the scope equitorially mounted. I might change that to alt az. I'm going to stay with the Flea3+0.5X FR for now for the high sensitivity and fast frame rates. As posted above, my other option is the T2i, but I think the transfer rate is too slow.

I have another window on Sunday morning and possibly another short one on Monday. Other passes are below the treeline. I won't get another chance 'til 12/10.

Enjoy your fishing trip north. One of my dreams is to take a kayak out on Great Slave Lake in the NWT for a couple of weeks.


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FoxK
Carpal Tunnel
*****

Reged: 11/07/07

Loc: Cape Cod, MA
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5547394 - 11/30/12 03:24 PM

Thanks Tim.....good luck....In a few more tries, it'll be easy for you to capture once you get into the groove. Just some info...............because of its orbital trajectory, you should expect the ISS to alternate between overflights in early evening and then it switches over to many passes in the early morning. Besides exposure.....you see how critical focus is....best bet is to do one more focus on a star 10 minutes before the overflight.....changing temperatures in a scope can really change the focus over time...I have a lil set screw I can use to lock the focus but just the pressure it puts on the foccus tube knocks the focus out enough to be useless so I do the 10 minutes before method and be VERY CAREFUL not to touch anything in the focal train. One more thing to watch for is sometimes with the cam etc attached, and the scope pointing near up at the ISS's brightest...the weight can pull the focus tube enough to ruin the shot......be aware.......ok.....that's all the advice I have lol........i'm sure you'll get it next try or the next.

Fox


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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: FoxK]
      #5547445 - 11/30/12 04:00 PM

Thanks Fox. I'm hoping the weather will cooperate for tomorrow. Fingers crossed. I think I messed up the focus when I started to manually slew... I bumped the camera.
Live and learn.
T


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zAmbonii
Carpal Tunnel


Reged: 01/19/08

Loc: Ypsilanti, MI
Re: ISS and Capella photo op planning new [Re: tjensen]
      #5547475 - 11/30/12 04:26 PM

You might not have been out of focus. When manually tracking You need a pretty high shutter speed so it doesn't smear. Also the ISS is going to change orientation and size as it moves across the sky and that is going to affect a final stack if there was a bit of time between the images you caught on chip.

What do your single frames look like?


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Jim Chung
Vendor - Icodome
*****

Reged: 12/07/05

Loc: Toronto
Re: ISS and Capella photo op planning new [Re: zAmbonii]
      #5547702 - 11/30/12 07:05 PM

It looks like too slow a shutter speed to me as well and not a focus problem.

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tjensen
Carpal Tunnel


Reged: 02/16/05

Loc: Chapel Hill, NC
Re: ISS and Capella photo op planning new [Re: Jim Chung]
      #5547759 - 11/30/12 07:41 PM Attachment (3 downloads)

I know the orientation changes... the stack was of 18 consecutive frames.

Could be a slow shutter speed... capture log indicates 116 fps with a shutter speed of 0.7ms (1/1428) I have no idea what others use.

Here is a composite of 6 of the 18 images that went into the stack.

So I'm curious... what techniques work?


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