Photographing the IIS

[sharptrack2]

Hi,

I've done my customary search and found 2 threads, but neither answered my question, which is... would you be able to get a single snapshot of the IIS, with enough detail to know what it was, passing across the moon, using a 127mm f5 refractor?

Reason for asking is that Friday morning 00:18 and that night 23:43, the IIS passes across the moon and the ground path for centre crossing will only be a couple of kms east of my house. According to Calsky, I should be able to see it cross very close to centre of the moon even though I am roughly 1.3km NE of the ground path.

I've got both Nikon and Canon cameras, so have my choice of full frame or not. I have 3 scopes to choose from, 8" SCT (not wide enough FoV IMHO), 127mm doublet f5, and a 90mm f5.5 no-name Chinese doublet. I also have 300mm standard camera lenses, but I don't think they would show enough detail. Would the SCT be the better choice for detail and try to time it right?

I'm also looking for suggestions on settings. Would it be appropriate to use an ND filter to be able to keep the moon from over exposing or will really fast shutter speed be good enough. I'm guessing ISO 100-200 maximum.

Thnx in advance

[BeanerSA]

ISS? This, is IIS?!

[rally]

This sort of thing ?
http://www.astrophoto.fr/iss_atlantis_transit.html

[sil]

Simple answer is yes. In practice a bit more tricky.

ND filter probably not, you should be shooting around 1/250 - 1/125 sec, no slower. Test shooting the moon at approximate phase first to nail down what settings you find acceptable for exposure of the moon (the ISS will be black / underexposed).

It will move across the moon quickly so use a good high speed burst mode to have a hope of catching it. Choose whichever camera gives you more pixels across the moon, should give you more detail of ISS (test before hand and measure for yourself to decide).

Basically you can go outside anytime before hnd and shoot the moon for yourself and decide what settings and gear to use to give you the exposure and detail you want.

Shooting ISS myself I've found it difficult to get an accurate prediction of both time and orbit for ISS when planning composition. They don't match up to the shots I get. EG if I can see in a program the ISS pass between two stars or bisects a cluster when I take a long exposure to get the ISS trailing in shot its path doesn't match. You can shoot ISS any time its visible for you and test.

Plan and test.

[sharptrack2]

Ooops! :screwy::rofl:

[sharptrack2]

Yes, something like that would be fantastic, but maybe a bit over-optimistic for me to achieve;):P



Which scope is better suited, the 127mm or the SCT? I would think if I want the most pixels I would want the narrower FoV to start. But as you mention, timing and exact tracking will be hit and miss. How do I measure the number of pixels? (this whole pixels per arc second and per FoV baffles me a bit... but I guess I need to learn it sometime :D )

I have a Nikon D7200, 24 MP, 6-7 f/sec, a Canon 5D, 20 MP, 4-5 f/sec, and a 7D that is supposed to be capable of 8 f/sec, but is only 18 MP. Recommendation?

[JA]

I would use the D7200 with the 127mm f5 (635mm), which would make it 1.5x635=~950mm mounted on an APS Nikon camera (D7200). This should fill the frame with the moon - check this before hand and if you are lucky give you the ISS-over-the-moon-shot that you said you were after with plenty of room to crop/zoom. Considerations:
1. Do you have lunar tracking on your mount? If so, set that and wait for ISS or try HD video (unfortunately much lower resolution, but much higher frame rate 30 or 60 fps on the D7200)
2. Check the buffer depth on the camera for how long you can shoot before full and also use a fast card.
3. Exposure - It may be diffcicult to get much detail on the ISS as it will likely be underexposed relative to the moon
4. Timing - very tight see Video at 0:30sec......https://youtu.be/Z1m_qG9cx7s?t=30s

Best
JA

[sharptrack2]

Got everything out tonight and ran a quick test...

1. Yes... HEQ5 Pro mount
2. 10 shots @ 1/200th sec automatically stops at 10 - maybe should use video instead like in YouTube example?
3. Most definitely... sample photo attached, I had to bump up the exposure 1 stop in post processing to get any detail visible on the moon, didn't help that it was hazy.

I'm thinking I might want to put in a 2X Barlow to increase the ratio of moon to frame and take the risk I might miss the station. Based on what I can glean and logic, I won't be able to see the station prior to its transit, so it will be a "wing and a prayer" attempt.

[JA]

One thing that that video clearly shows (from 0:30sec onwards) is how short the transit time is for the ISS across the moon. Sub 1 second - around 1/2 second. That means you need to be on the ball to catch it photographically as at best you will only get 3 or 4 shots across the moon in 1/2 second at say 6-8 fps. That doesn't even factor any reaction time. And look how small a flea the ISS appears against the moon - difficult to see. So short of some sort of automation/motion detection to get the shot photographically - go to video. On your camera you could try 30fps and 60fps @1080p. Of course 4K would be better, albeit probably at 30fps.

Best
JA

[sharptrack2]

May all be for naught... looks like my parade will be rained on, literally. :rain:

Best chance was Friday morning just after midnight, second crossing Friday night has a ground path farther to the south by a good 2 kms or more, but now weather is forecast to be overcast for the whole day. :( :cloudy: