timelapse - Milky Way

[Les R]

I am currently on holiday in Tenerife (lucky me!) lol

I intend on taking a trip up Teide at night to take some time lapse of the Milky Way (and anything else thats there of course!) Looking through You Tube clips and different bits of info, I'm unsure of the settings I should be using. They also say you must use manual (and not rely on what the camera tells you.)

So, obviously from the base of Teide, there should be no light pollution. (The lower cloud base should filter out any stray light from the resorts 30 miles away!) From what Ive read, I should be selecting a very high ISO, low aperture and up to 30 seconds exposure for each shot. The last part is the killer, as I dont think we are there for more than 2 hours! We are going as part of a trip, but I'm thinking I might be better off going on my own and staying longer. (If the missus will let me of course! lol)

Anyway, I know some of you have had a play with this sort of stuff, so any tips would be useful. I intend on using two tripod mounted cameras (my old trusty canon 300D with timer - and my newer 550 with firmware upgrade.

Also.... anyone know of any links that show details of cloud info? Its a long drive to get to Teide and find its cloudy! (Obviously clouds at sea level are irrelevant!)

Problem I mostly have is the fact I'm one of those lazy photographers that tend to use auto settings far too much! I've had a daytime play with timelapse which worked really well - but auto settings used!

Link to my first attempt at timelapse in Switzerland.... http://www.youtube.com/watch?v=5khQMFnqvLs


Apologies if this is the wrong place to ask! Please move if so!

[MarkS]

Les,

It all depends on the focal length of your lens.   I'm assuming you are putting the camera on a fixed tripod. Too long an exposure and you will suffer obvious star trailing.

At 18 mm I would say use an exposure of 10-20 sec though I have just about got away with 30sec in the past by shrinking the image later to disguise the trailing.
At 50 mm use at exposure of 3 -6 sec - maybe 10 seconds at a pinch.

These settings will both result in some moderate trailing but you will need a reasonable exposure to overcome the CCD read noise and make the Milky Way visible.  You'll also want a fairly high ISO - 800 or more.

In any case take a careful look at your first exposure - if you feel there is too much star trailing then reduce the exposure time.

Mark

[Les R]

Thanks Mark

I imagine Id be using either 18 or 24mm focal length to get maximum sky. The trip we have planned only gives us 2 hours at the mountain base, so time is limited to experiment. I have thought about doing two trips (the organised one is on Wednesday - and we leave Friday morning, so things are a bit tight.) Its a clear blue sky today too!

[Mike]

To get the maximum exposure length you can use without trailing stars use the '600 Rule'. That is, take 600 and divide it by your focal length and that will give you the exposure length in seconds.

E.g. With a 50mm lens then take 600/50=12 seconds.

You may need to decrease this if there is noticeable lit pollution but anything over 12 seconds (for a 50mm lens) would produce trails.

[MarkS]

For a camera whose CCD has a 5.5 micron pixels (an average DSLR), the 600 rule would give star trails 8 pixels long.  You certainly wouldn't want longer exposures than that.

You want to use a fast F-ratio e.g. F/2 or F/2.8 but on the other hand that might lead to unacceptable optical aberrations (star distortion) in the corners of the image.  So F/4 might be a better compromise.   You might be able to test this on a bright star in the edge of the field of view one night before you go. 

Mark

[Les R]

OK cheers guys.

Ive got a pass out tonight to head up the mountain, armed with the two I will hav cameras and tripods a laptop (for larger image viewing) and a helper aged 12. Before letting them loose on the timelapse, Im hoping that I will have everything optimised.

So just going with rough figures, 5 seconds, 1 second gap = 2m 30s= 1 second of viewing. So 1 minunte = 2h 30m - Does that sound right?

So all systems go for this evening and also a meal a shorter viewing session on Wednesday.

[MarkS]

Your calcs sound right but remember you don't have to view it as fast as 25 frames per second.

[Les R]

I went up last night... excellent night sky as expected. I went with 5 seconds F4.5 18mm on the 550D. Bright stars clearly visible, but the mist of the milky way doesnt appear to show up in the photos. Had no joy at all with the 300D. Couldnt get the timer sorted for it. With the LCD too small and no CF card reader, I just used it to take same snaps. But to be honest, once night came, it was nigh impossible to do anything with focus and all was fingers crossed time.

Rather anoyinging, a car pulled up full headlights into the path of the camera. The driver and passenger getting out leaving headlights and internal lights on before being told to turn them off. Then being treated to 10 minutes or so smoochy smoochy! I was like .... get a room! Then 15 minutes later another car pulls up on the road edge and stops, headlights off, to smoke and leave the bright internals on! They turned off when asked.

I had planned on staying later than I had, but on the horizon, the bright headlights I could see, turned out to be the moon and game over as it rose. I have a feeling it will be an earlier end on Wednesday evening in the planned excursion.

I was half expecting to see lots of colour as seen in the timelapse clips, but just a cloudy mist. Is that done post production?

[MarkS]

I went with 5 seconds F4.5 18mm on the 550D. Bright stars clearly visible, but the mist of the milky way doesnt appear to show up in the photos.

Yes, you can increase the brightness during processing which might help.  But 5 second exposures are rather short.  Shame you weren't able to do a few test exposures first.

You may end up having to perform some kind of rolling average substack e.g.
frame 1 = stack of 1,2,3,4
frame 2 = stack of 2,3,4,5
frame 3 = stack of 3,4,5,6  etc.#

Mark