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Thread: Chasing star trails with an 8x10

  1. #1

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    Chasing star trails with an 8x10

    I've got permission to spend as much time as I want between 7:00PM and 7:00AM in a special place, directly South of a landmark I want encircled by star trails. I have an idea where the moon will be rising and setting to avoid getting it in the shot courtesy of
    https://www.cambridgeincolour.com/tu...calculator.htm
    Aside from the 1/2 mile hike in and out sugar anting the 8x10, tripod, thermos bottle and lawn chair, I have my choice of HP-5+ or FP-4+ emulsions.
    Which film do you recommend?
    The lens will be either a 14" Commercial Ektar or 10" Wide Field Ektar
    I also have to select an evening that will be cloudless, like under a high pressure system, which should be easy enough to predict this time of the year.
    I also have to determine which phase of the moon will offer the best light for my purpose---I'm thinking a full moon might be too bright, washing out the night sky.

    It has been a long time since I did any night photography and I can't even recall shooting any star trails using large format.

    If the North Star is directly behind my target, the star trails should make complete circles, right?

    Is there anything else that needs taking into consideration?
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  2. #2
    Gary Beasley's Avatar
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    Re: Chasing star trails with an 8x10

    Personally I would use Acros for its reciprocity characteristics. Faster film will give you fatter trails on the bright stars so you should previsualise with that in mind.

  3. #3

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    Re: Chasing star trails with an 8x10

    Quote Originally Posted by Gary Beasley View Post
    Personally I would use Acros for its reciprocity characteristics. Faster film will give you fatter trails on the bright stars so you should previsualise with that in mind.
    I'm tending towards shooting during a New Moon with HP-5+, for 1 hour at f/8. I wasn't aware that Acros is available in 8x10 although I think Tmax 400 may still be?
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  4. #4

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    Re: Chasing star trails with an 8x10

    The sky is a 24 hour "clock", so for full circles you need to expose for that, but there is that pesky thing called daytime that will blow out the exposure...

    But don't fear, after a long enough exposure, other stars will help fill the incomplete circle...

    To really get a complete-like effect, you need to expose from after sunset, to before sunrise... Light pollution will start fogging dark areas after not too long time... That can be kept lower by shooting through a dark red filter... Stars themselves are quite bright and will record as they move well...

    This is a better project to do if you stay up all night while camping, while one camera is open the entire time... Shorter exposures only record shorter segments of the arcs...

    Bring mosquito repellent!!!

    Steve K

  5. #5
    Vaughn's Avatar
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    Re: Chasing star trails with an 8x10

    Aperture will affect the width and sharpness of the trails. Aim of those middle ones, f16 or f22 or so, for narrow sharp trails.

    Unless you are bringing it or there is lighting on the landmark, it will be siloletted (sp?), so choice of film is not that important...faster film for more contrast between the sky and stars at the same aperture (more exposure of the stars while sky remains black). Reciprocity failure will not affect the exposure of the stars themselves and will help keeping the sky dark. So the exposure you want on the landmark will determine a lot of your exposure needs.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

  6. #6

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    Re: Chasing star trails with an 8x10

    When the moon is down or new you will have much, much darker skies. If the moon is a thin crescent and you're facing away from it (which you should be, shooting North) then it doesn't brighten the sky very much. IOW, chase both the moon and weather: better to have a thin crescent 1 or 2 days from new moon and clear skies, then perfect new moon but clouds.

    At a dark site with long exposures, the difference between nautical twilight (sun 12 degrees below horizon) and astronomical twilight (18 degrees) is noticeable to the film / detector, even if not to your eyes.

    Star trails will be centered on the North Star, but the length of the arc depends on your exposure. So if you expose for 1 hour trails will be 1/24 of a circle.

    A partial moon low on the horizon (just at moon rise or set) can give a gentle illumination to objects in the foreground, because the light is reduced a lot by the atmosphere and the angle is low - it's basically the moon equivalent of the golden hour. If you were shooting color, the moonlight is actually warm in color temp because the moon's albedo is red (plus reddened by the atmosphere). Color or B&W, sometimes the partially-moonlit landscape combined with star trails is interesting.

    So given the effort to get your gear in there and set up the shot, it could be worthwhile taking images spanning moonset (or rise) and several images of different exposure lengths in dark time, at as fast an aperture as you are comfortable with. Don't forget a flashlight, a red light, and a timer/stopwatch/alarm clock.

  7. #7

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    Re: Chasing star trails with an 8x10

    Quote Originally Posted by reddesert View Post
    When the moon is down or new you will have much, much darker skies. If the moon is a thin crescent and you're facing away from it (which you should be, shooting North) then it doesn't brighten the sky very much. IOW, chase both the moon and weather: better to have a thin crescent 1 or 2 days from new moon and clear skies, then perfect new moon but clouds.

    At a dark site with long exposures, the difference between nautical twilight (sun 12 degrees below horizon) and astronomical twilight (18 degrees) is noticeable to the film / detector, even if not to your eyes.

    Star trails will be centered on the North Star, but the length of the arc depends on your exposure. So if you expose for 1 hour trails will be 1/24 of a circle.

    A partial moon low on the horizon (just at moon rise or set) can give a gentle illumination to objects in the foreground, because the light is reduced a lot by the atmosphere and the angle is low - it's basically the moon equivalent of the golden hour. If you were shooting color, the moonlight is actually warm in color temp because the moon's albedo is red (plus reddened by the atmosphere). Color or B&W, sometimes the partially-moonlit landscape combined with star trails is interesting.

    So given the effort to get your gear in there and set up the shot, it could be worthwhile taking images spanning moonset (or rise) and several images of different exposure lengths in dark time, at as fast an aperture as you are comfortable with. Don't forget a flashlight, a red light, and a timer/stopwatch/alarm clock.
    Good stuff. Thanks!
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  8. #8

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    Re: Chasing star trails with an 8x10

    Quote Originally Posted by LabRat View Post
    The sky is a 24 hour "clock", so for full circles you need to expose for that, but there is that pesky thing called daytime that will blow out the exposure...

    But don't fear, after a long enough exposure, other stars will help fill the incomplete circle...

    To really get a complete-like effect, you need to expose from after sunset, to before sunrise... Light pollution will start fogging dark areas after not too long time... That can be kept lower by shooting through a dark red filter... Stars themselves are quite bright and will record as they move well...

    This is a better project to do if you stay up all night while camping, while one camera is open the entire time... Shorter exposures only record shorter segments of the arcs...

    Bring mosquito repellent!!!

    Steve K
    Definitely mosquito repellent. Thanks!
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  9. #9

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    Re: Chasing star trails with an 8x10

    Quote Originally Posted by Vaughn View Post
    Aperture will affect the width and sharpness of the trails. Aim of those middle ones, f16 or f22 or so, for narrow sharp trails.

    Unless you are bringing it or there is lighting on the landmark, it will be siloletted (sp?), so choice of film is not that important...faster film for more contrast between the sky and stars at the same aperture (more exposure of the stars while sky remains black). Reciprocity failure will not affect the exposure of the stars themselves and will help keeping the sky dark. So the exposure you want on the landmark will determine a lot of your exposure needs.
    Lighting will be an issue. There's no power to the site and it's in a pretty dense forest, so I'll be stuck with a silhouette I'm guessing. Thanks!
    I steal time at 1/125th of a second, so I don't consider my photography to be Fine Art as much as it is petty larceny.
    I'm not OCD. I'm CDO which is alphabetically correct.

  10. #10
    Drew Wiley
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    Re: Chasing star trails with an 8x10

    John, ACROS 8X10 would be very difficult to find, because the tiny bit remaining is probably being jealously hoarded. I used up my last sheet of it a couple years ago. TMax400 is going to be no.2 choice in terms of long-exp characteristics, and will be way sharper than HP5. FP4 sounds awfully slow. Test any of these in 35mm first. Someday I'll have to show you the secret UFO landing site up above Granite Creek. It was about 5 mi back in the woods, and once a summer a UFO cult would gather there and wait in a circle holding hands and chanting. Finally it happened. Of course nowadays if some frisbee with flashing perimeter lights went over someone's back yard BBQ at night they'd just snicker about what the neighbood kids were up to. But in the mid-60's, way back miles from even the nearest dirt road, who would have imagined some kids would design a very elaborate model and giant slingshot device, and haul in six car batteries for sake of powerful projector black light strobe system, just to make fools out of what were already fools? But that 12-second UFO overflight was good for a lifetime of laughs afterwards, and it sure made true believers out of them.

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