Help with star trails.
I am going to the northern area of michigan were there will be little ambient light, and more stars, and i will be on lake michigan, so i thought this would be a good opportunity to experiment with photographing star trails. My format is 35 mm, and i plan to use color film.
Does anybody have any quick rules of thumb or tips for me? Thanks a lot to all that do,
Where is the art in digital photography?..
I'd say just use common sense... the length of the trail will be based on the rotation of the earth - so for each hour the shutter is open, the trail will traverse 1/24 of 360 degrees (which probably look bigger than you think).
Here's a google image search showing star trail photos with the search term "minutes" - so the exposure length should be indicated on them. Probably a medium-speed film would work best (too slow a film may not get enough ambient light to make an interesting photo - but you should try both). See what these guys used.
GREAT first image. Amazing! Apparently fogging is a HUGE issue. Beware!
basic rule for this, and the similar subjects of lightning and fireworks, camera on tripod, shutter on B, aperture on f8, expose for as long as is required to capture the scene, cover lens between events if necessary, add flash to near ground objects to render detail
Sky fog is a problem as mentioned before. You can print through sky fog with negatives to some extent, but not with transparencies. Another problem is color shift (different rates of reciprocity failure in different emulsion layers), but that can mostly be balanced out by a lab with most modern negative films. For slide film, try Ektachrome 200, which has little reciprocity failure and very little color shift, and the color shift tends to a pleasing blue that seems more natural than red or green shifts.
Sky fog will depend heavily on your observing site, so get away from local lights as much as possible. Bracket exposures widely. If you have time to get results back and try again, you can keep notes and find the longest time that you can run without sky fog.
Go here: http://cleardarksky.com/csk/prov/Michigan_clocks.html to find a dark sky nearby and look at the column for light pollution. You can get a map of the sites, or go to an observatory on that page. Once on an observatory page, you can click on a link to light pollution and get a light pollution map of the area to look for public places to shoot or find out how good your location is. From the light pollution map you can display a Google map of the area with streets, etc.
Stars will trail 15 degrees per hour.
Let me know if you have other questions.
Last edited by Lee L; 08-14-2006 at 09:36 AM. Click to view previous post history.
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Tip: if you want the circular star trail look, point your camera towards the north star.
"...slow down and start using photography to create an image, not just capture one." b.e.wilson
"Speed kills, Del" Johnny Fever
A little hint, if you are getting your film processed at a lab it is a good idea to take a daylight shot first so they know where to cut the negatives. A rough guide for 400 speed film is f3.5 or f4 for exposures up to an hour. If you have plenty of time take several shots for different lengths of time. You will be surprised how many stars show up on film that you couldn't see yourself. Also the colour is pretty cool too. Good luck.
"Out, damned spot! out, I say!" - Lady MacBeth
As has been suggested, the star trails will be more interesting nearer to one of the poles, in your case north. At your latitude that should be high enough up to avoid including ground objects.. unless you wanted to, which may be interesting, too.
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Anyone can appreciate a fine print. But it takes a real photographer to appreciate a fine negative.
And if a person doesn't know where Polaris is, it's easy: in the northern hemisphere, it's due north, and it is as many degrees above the horizon (assuming a level horizon) as you have degrees of latitude at your location. For me, I'm at 50.5 degrees north, so Polaris is 50.5 degrees above the horizon. Roughly. Curvature of the earth overstates this a bit, but that's being picky.
Originally Posted by dschneller
In the southern hemisphere there is no obvious "south star" although the Southern Cross, Crux, can point you there. The same rule applies in reverse though. Look south. Look above the horizon the same as your latitude south of the equator.
At the equator, both celestial poles are at the horizon, one north and one south.
Jim MacKenzie - Regina, Saskatchewan, Canada
A bunch of Nikons; Feds, Zorkis and a Kiev; Pentax 67-II (inherited from my deceased father-in-law); Bronica SQ-A; and a nice Shen Hao 4x5 field camera with 3 decent lenses that needs to be taken outside more. Oh, and as of mid-2012, one of those bodies we don't talk about here.
Favourite film: do I need to pick only one?
SKY FOG?? Ain't got nuthin' to do with SKY FOG. You mean light pollution - if you were referring to the earlier comment about fogging being a major concern - I was talking about LENS fogging. It's kind of hard to get any kind of shot without some kind of lens heater. See the article. It's pretty informative. Light pollution is light pollution - we just do with what we have. It can be pretty, even.
Originally Posted by Lee L