Photographing Planets

[ronin]

I have no idea where I got the value of 90 seconds from, it is/was sort of lurking at the back of my mind. But that is the only one I can recall reading somewhere.

Will add the caution that it may be a maximum if and when conditions are right and the gods are smiling. Could equally be someone deciding they can get longer duration then the rest of us mere mortals and posted it. Whatever happens Jupiter is limited in duration, and it is not necessarily a long movie that you can take of it.

Still it is all software and there is the delete file option. :grin:

[JamesF]

And I stupidly forgot JamesF, he has also done some amazing images on a 127mak.

Sorry James. 

No apology necessary

James

[JamesF]

I have no idea where I got the value of 90 seconds from, it is/was sort of lurking at the back of my mind. But that is the only one I can recall reading somewhere.

Will add the caution that it may be a maximum if and when conditions are right and the gods are smiling. Could equally be someone deciding they can get longer duration then the rest of us mere mortals and posted it. Whatever happens Jupiter is limited in duration, and it is not necessarily a long movie that you can take of it.

Still it is all software and there is the delete file option. :grin:

If you have exceptional seeing and you're up a mountain in the Atacama with a big scope then very short imaging runs may well be the goal.  I worked through the maths a while back and the theoretical maximum depends on how fast the target planet turns, how wide it appears in the sky, the focal length and aperture of the optical system and the pixel size of the camera.  On top of that there are the restrictions imposed by the quality of the seeing.  It's all very well for example deciding you don't want more than 0.25 arcseconds of movement in your imaging data, meaning you need a very short imaging period, but not entirely helpful if the seeing isn't good enough for better than 2 arcseconds resolution, for example (which is probably not that bad for the UK).

Any statement of the maximum imaging time therefore ideally needs to be put in context otherwise it can be misleading.  The 90 seconds you remember could therefore be absolutely correct for the circumstances of the person who wrote it

James

[Freddie]

There have been quite a few threads recently with people talking about rotation blur and duration of AVIs. Most people state very short durations but as James has said these tend not to be based on real world imaging. My image below was at 9.4m FL and from a 3 minute AVI. A 3 min AVI is therefore a good starting point for by far the majority of images and at shorter FLs (which most will be using) the smaller image scale would allow an even longer AVI. I'd therefore suggest for most people, go for 3 mins to ensure you get a decent number of frames to work with and stop worrying about rotation.