Planet images with a UC18...

[ram]

I really should've gotten a classic Obsession instead of the UC 18 --- I bought the UC since I thought it looked cooler. Anyways, what's done is done and since I do a lot of AP these days, I don't use it that much. I'm starting to get around this but I'm wondering about taking pictures with it. Obviously any kind of long exposure DSO imaging would be difficult with a non-GEM but why not planets and planetary nebulae where exposure times are very short - this should be doable right? Or will the vibrations be too much?

I ask because I saw the really awesome images of the ISS being taken by someone who is holding their C8 on their shoulders (if even that) and just snapping pictures as it goes by. I thought if they can do that, I should be able to use my UC18 to take fast exposure shots right? I need to go back and look into planetary imaging but I imagine being able to stay on a target for a total of about 100 seconds should be okay if I take 10 images per second right?

If it would work it would probably better than my C925 for planetary imaging. Or is that really true? The C925 is 2950mm FL and at F/10 (but I can put it on a GEM). The UC18 is F/4.2 and a focal length of 1920mm. So has anyone done any kind of imaging with a UC18 here?

--Ram

PS: It's already started to get cold where I am so I probably have another month or so left of this season to image. Sad...

[OzEclipse]

Hi Ram,
Give it a try. The thing to remember about the ISS is that it is illuminated by sunlight same distance from the sun as the Earth and Moon and so exposures are similar to daytime landscape exposures and very short - perhaps around ISO1600, 1/3000s @ f10. I am not a planetary photographer so others can no doubt give better advice.

Planets are a lot farther from the sun and therefore need longer exposures. So then it's a question of whether the motion due to earths rotation will be handled by the short exposure. Just using a simple 1/d^2 exposure rule:-

ISS............1.0 AU.......ISO1600, 1/3000s @ f10.
Mars..........1.5 AU.......ISO1600, 1/1500s @ f10.
Jupiter.......5.2 AU.......ISO1600, 1/90s @ f10.
Saturn........9.5 AU.......ISO1600, 1/30s @ f10.

I have an 18" f5.5 which is a smooth push scope and quite solid, no vibration. I have only attempted photos of the Moon not the planets.

Joe

[JayTee]

Ram,

Plug your 120MC-S into the eyepiece, get it focused and shoot Jupiter. See what happens. I think you'll be surprised even though your focal length may not be optimal the resolution should be stunning.

Cheers,
JT