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  1. #11
    Sirius Glass's Avatar
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    Quote Originally Posted by 2F/2F View Post
    Steve,

    Wouldn't f/11 or f/16 be too tiny an aperture for this?
    It has been years since I tried this, so yes it may be too small an opening. I was thinking about the ambient light causing the background [trees, etc] becoming too bright.

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

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  2. #12
    Sirius Glass's Avatar
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    2F/2F,

    You are right. From the FotoSharp "Day & Night Exposure Guide" - www.FotoSharp.com

    "Star Trails - Use a tripod with fast film (ISO 200 or faster) and a wide aperture. With landscape or foreground subject in the scene, determine the desired exposure for the landscape or foreground using an aperture that allows an exposure of 20 minutes or longer. For circular trails, aim your camera at the North Star and expose the film for 20 minutes to several hours."
    Steve
    Last edited by Sirius Glass; 08-14-2009 at 05:02 PM. Click to view previous post history. Reason: Added website
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  3. #13
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    Forget about reciprocity failure, since your shots will be at least 30mns.
    The smallest aperture, the less stars you will get (only the brightests). No need for small aperture (smaller than f/8) since you dont need depth of field either.
    Also, you will not overexpose in your case (away from city lights) so you can focus at infinity and set aperture at f/5.6 to 8 for at least 30mns for a bit of trailing. Then before going to bed, open the shutter and wake up before dawn (then for safety leave smaller aperture if you oversleep).
    Best time for this is full moon, when you actually capture landscape as well.

  4. #14
    Sirius Glass's Avatar
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    Quote Originally Posted by calceman View Post
    Best time for this is full moon, when you actually capture landscape as well.
    Yes, but keep the moon out of the field of view to avoid a burned out white blur. Also be aware that if the Moon passes close to the camera lens longitudinal axis, then the Moon may cause flares in the photograph.

    Stev
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  5. #15
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    The way I understand it, the aperture determines how many stars of each intensity are captured. The wider apertures show more of the fainter stars on the film, and the more you stop down, the more of the faint ones get cut out.

    But I do not know at what apertures you also start to lose the brighter stars.

    I have also heard, but not tested, that the angle of view affects this by showing more or less of the sky, which can gain density due to fog/haze and obscure some stars. Thus it is more important to have a wider aperture on a wider lens, to allow the stars to better appear to "burn through" the fog/haze on the picture.

    I have only shot star trails a few times. Only a few scenes have inspired me to do so. I used f/4 - f/8 and a 100-speed film in a Mamiya M645 with a 55mm lens and all-night exposures. Pix came out OK. F/5.6 seemed to be the best for the conditions at the time. Film was Fuji Reala, which is not the best as far as reciprocity, but also not the worst.

    I set up my shot, put the lens cap on, took the camera off the tripod, removed the quick release plate, opened the shutter on B, removed the battery, put the quick release plate back on (hopefully aligning it the same exact way), put the camera back on the tripod, and then removed the lens cap.

    I don't know if this was necessary, but I assumed that since the camera has an electronic shutter, that it would be burning through the battery if the camera was left open on B.
    Last edited by 2F/2F; 08-14-2009 at 05:32 PM. Click to view previous post history.
    2F/2F

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  6. #16
    Sirius Glass's Avatar
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    Quote Originally Posted by 2F/2F View Post
    I have also heard, but not tested, that the angle of view affects this by showing more or less of the sky, which can gain density due to fog/haze and obscure some stars. Thus it is more important to have a wider aperture on a wider lens, to allow the stars to better appear to "burn through" the fog/haze on the picture.
    The wider the field of view the more impressive the photograph becomes. I do not remember the details of my early work to recall the "burn through" factor [Whether or not it exists.].

    Steve
    Warning!! Handling a Hasselblad can be harmful to your financial well being!

    Nothing beats a great piece of glass!

    I leave the digital work for the urologists and proctologists.

  7. #17

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    Thanks guys, this is some really great advice! A few questions, though.

    Quote Originally Posted by calceman View Post
    Forget about reciprocity failure, since your shots will be at least 30mns.
    Wait. Now I'm confused. Doesn't the reciprocity failure come into effect when the exposure gets long (eg 30 min exposures)?
    Then before going to bed, open the shutter and wake up before dawn (then for safety leave smaller aperture if you oversleep).
    Best time for this is full moon, when you actually capture landscape as well.
    Cool idea! Whether I do this or not will depend on how much I trust my campsite neighbor not to steal my camera!
    Quote Originally Posted by 2F/2F
    The way I understand it, the aperture determines how many stars of each intensity are captured. The wider apertures show more of the fainter stars on the film, and the more you stop down, the more of the faint ones get cut out.
    Ahh good point. So, from what I gather, it's not really possible to over expose the stars. What I have to watch out for is overexposing the landscape and the moon (if it crosses through the picture).
    I don't know if this was necessary, but I assumed that since the camera has an electronic shutter, that it would be burning through the battery if the camera was left open on B.
    I'm using a fully mechanical camera (except for the meter), so this shouldn't be a problem. I'm guessing that an all night exposure probably isn't too good for the components though (would springs, etc get stretched out?).
    Quote Originally Posted by jnanian
    i may have the star wrong but if you point to polaris
    ( north star/end of the handle of the little dipper )
    all the stars will make concentric circles around IT ...
    polaris doens't rotate ...
    Good idea. I'll have to take a star chart and get somewhat familiar with the sky so I can plan out my star trails.

    In any case, it sounds like I'll have to use all this as a starting point for some test rolls I'll be shooting over the next few nights. They'll be in the city, but hopefully it'll give me a little closer idea of how the reciprocity failure, etc will affect my film (Fomapan 200).

    Thanks guys!

  8. #18
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  9. #19

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  10. #20

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    Quote Originally Posted by beala View Post
    Doesn't the reciprocity failure come into effect when the exposure gets long (eg 30 min exposures)?
    It sure does.
    But you're no longer trying to use an exposure meter and figure out how you have to deviate from what it says to get a good exposure.
    Exposure times are based on experience and are often paired (though perhaps not explicitly) with advice about what film is less or more suited for the purpose.
    It is a hit and miss affair, but without the "miss" part: you always get a result.

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