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Pfiltz
13-Jul-2013, 05:30
last night in an effort to get star trails. Was a beautiful night. Weather has cooled down toward the end of the week. Not that it's been terribly hot anyway.

I was using Foma 100 4x5 film. I placed the camera in a small field around 8:00 to get focusing. I walked back out at 9:00 to cock the shutter, and pull the black slide out. Walked back at 10:15 to closed the shutter, only to find out that the front of the lens was covered in moisture.

Kind of bummed out on that moisture part.

Any ideas on how to shoot something like that? I have NO light pollution here in the sticks.

Jim Jones
13-Jul-2013, 06:34
This is a problem that has long plagued astronomers. This link explains the problem and some solutions: http://www.astronomy-education.com/index.php?page=188. I improvised a heated dew shield from a rectangular tin can, a resister from a box of radio junk parts, and old filter rings to mount it on the camera. It takes only a very few watts of power to eliminate dew on night-long exposures. Mine is a 120 volt model, but one powered by rechargeable batteries should be practical for remote locations.

Corran
13-Jul-2013, 07:15
To be fair, with the abysmal reciprocity failure of that Foma, I doubt you'd have gotten anything on film anyway. I've had limited success with T-Max 100 and long exposure and it has better reciprocity.

I've never had dew on my lens, except when I would come out of a cool car into hot humid evening, at least here in the Deep South.

Pfiltz
13-Jul-2013, 07:35
To be fair, with the abysmal reciprocity failure of that Foma, I doubt you'd have gotten anything on film anyway. I've had limited success with T-Max 100 and long exposure and it has better reciprocity.

I've never had dew on my lens, except when I would come out of a cool car into hot humid evening, at least here in the Deep South.

Well, how do they shoot it then, or are you saying you can't shoot star trails with LF film?

Jody_S
13-Jul-2013, 07:38
I did most of mine in winter, at -20 degrees. The air was dry enough that no frost formed on the glass.

98723

Greg Miller
13-Jul-2013, 07:47
last night in an effort to get star trails. Was a beautiful night. Weather has cooled down toward the end of the week. Not that it's been terribly hot anyway.

I was using Foma 100 4x5 film. I placed the camera in a small field around 8:00 to get focusing. I walked back out at 9:00 to cock the shutter, and pull the black slide out. Walked back at 10:15 to closed the shutter, only to find out that the front of the lens was covered in moisture.

Kind of bummed out on that moisture part.

Any ideas on how to shoot something like that? I have NO light pollution here in the sticks.

Just hang by the camera and check the lens periodically. Wipe the lens if a bit of dew has formed. It only takes a couple of seconds so will not affect the photo. Take a stool, sleeping bag, or blanket and listen to photo podcasts to kill the time.

Also, keep the lens at ambient air temperature before shooting. Check the weather forecast to see where the dew point is relative to the actual temperature. Clear nights allow for a lot of cooling of the air which in turn raises the risk of condensation on the lens as warm moist air cools to the dew point.

Jim Noel
13-Jul-2013, 07:56
If you want star trails you need to think of exposures longer than one hour. The stars only move 15 degrees per hour.

Corran
13-Jul-2013, 07:56
No, I'm not saying that, I'm saying that you need to use an appropriate film for the task. Having used some Foma 100 in 120 that stuff would lose the shadows even for a 2-second exposure, so if the "correct" exposure was 1 hour, you'd probably have to give it 4-5 before it was even close to being exposed enough, and might never get there. Acros or Provia would be a much better choice, or any number of films with better reciprocity.

I've done a lot of startrail stuff with digital and film, and it's a challenge, and you have to experiment and learn and really practice it. Haven't gotten to do any in almost a year because of poor weather, but here's a shot on Provia that I believe was about an hour exposure, taken with a 35mm Fisheye / Pentax 67 (edit: that jpeg looks terrible after resizing, oh well):

http://www.oceanstarproductions.com/photosharing/036.jpg

I saw a lovely image of the New River Gorge Bridge up in West Virginia a couple years ago, taken on 4x5 with TMX I think (65mm lens). I don't remember the photographer but it was really great and I think it was a 4-5 hour exposure.

With respect to Jim, the amount of "apparent" movement in the stars depends greatly on which direction you are looking. The closer to the poles, the less they'll move, the further from them, the more they will move. Yes, 15 degrees per hour, but different size "circles."

Jac@stafford.net
13-Jul-2013, 07:57
This is a problem that has long plagued astronomers. [... snip good article ...]

I don't know if they are still available, but I got a couple heated aerial camera-port windows from www.surplusshed.com.

Pfiltz
13-Jul-2013, 08:15
Appreciate it guys..

Don't know much about film or foam's reciprocity characteristics. Haven't shot much film to be honest. Just started around 9 months ago.

I may have some other films in the freezer I can consider as well.

vinny
13-Jul-2013, 08:46
Appreciate it guys..

Don't know much about film or foam's reciprocity characteristics. Haven't shot much film to be honest. Just started around 9 months ago.

I may have some other films in the freezer I can consider as well.
you may want to go back and read your earlier thread and take some of the advice there.
it's nice to be able to compose during daylight hours but if it's focus you're concerned about, just focus on infinity (or just something way off) druing the day and leave your camera set up.
acros, tmy, fp4, tmx are all better films suited for this type or work.
put on a lens hood or shade, that helps with moisture.
go to flickr*, search star trails in the large format group, pick a proper film, open the shutter, set an alarm for several hours later, go to bed.
for example http://www.flickr.com/search/?q=large%20format%20star%20trails

Greg Miller
13-Jul-2013, 09:13
I would advise against going home to bed. A lens pointed up will get dew or frost, even with a lens hood. Even in the most remote area planes and satellites with their blinking lights will fly over. Heavy clouds will appear even on otherwise clear nights. An inquisitive deer will come by an nudge the tripod. Lightning will occur on the horizon. These are all things I have encountered in the middle of the night that will spoil a star shot. Better to be there and, either end the exposure, or cover the lens momentarily to save the shot. And besides, most of the successful star trail photos range from 30 minutes to 3 hours.

Vaughn
13-Jul-2013, 09:57
I would not worry too much about reciprocity failure (rf) with star trails. As it is the shadows that drop out -- how black can the night sky behind the stars get? The stars sit above the effect of the rf, and trees, etc will often be silloeted anyway. But Acros seems to have the least problems with long exposures. Not always easy to find. TMax400 would be another nice film to work with.

How about a small battery operated fan mounted on another tripod blowing gently across the lens?

I have the reverse problem occasionally -- 'dew' forming on the inside surface of the lens. Living and working here on the north CA coast, my bellows maintain a relatively high moisture level (but not high enough for mold, so far). When I take the camera to Yosemite, or to the desert, and I set for the first time, the sun hitting the extended bellows causes my camera to steam-up inside. I'll be looking at the image on the GG and the focus and sharpness start to disappear. I have to take the lens board off and the back and let it air out inside!

Vaughn

PS -- once backpacking in the Grand Canyon, I set up my 4x5 centering on the North Star that was perched right above one of the Grand Canyon temples. Right from my little camp. perfect. Except I opened the lens but then fell asleep and did not wake until first light.

Photo Dave
13-Jul-2013, 10:00
I wouldn't bother... to much trouble... a waste of film... listen to the pessimistic critics... stay home and sleep!

But... I do this a lot. I live in the desert so have never had an issue with dew, but I am concerned with frost. I shoot most of my star trails in the winter... longer nights. When it does become an issue I think I'll visit Radio Shack and pick up a small battery pack and small cooling fan (muffin fan). Rig up the fan on a goose neck thing clamped to the tripod out of view and blow a small amount of air across the front of the lens... a defroster. I'm assuming that will take care of the problem.

I shoot MF (until the Wanderlust PS becomes available!) FUJI RDPIII, f8 or f5.6, 4 - 4.5hrs.
I start late, most of the planes have gone to bed after 11PM so you have less chance of blinky lights across your image.
"abysmal reciprocity failure"... color shift... PS it!
"An inquisitive deer" Yes I've had a smudge on my lens in the morning... now I do a pee dance around the tripod before I leave it for the night. There's always a simple fix to a problem.

Yes star trails are a challenge... that's why you don't see many good ones. Experiment, try new things... but have Fun!
Good luck.... Dave
98727

tgtaylor
13-Jul-2013, 10:13
A lens hood (aka dew shield in astro circles) will keep the dew off the optics for a longer period of time than without a shield. To keep it off all night, I place a dew shield on my 10" telescope and a dew zapper by the front objective: http://www.telescope.com/Accessories/Dew-Control/Orion-Dew-Zapper-Pro-4-Channel-Prevention-System/pc/-1/c/3/sc/44/e/22.uts The heating elements come in various sizes to fit everything from eyepieces to objectives of large telescopes. You can power them off your car battery/cig lighter. I use a Celesgtron 19Amp battery pack but I'm also running the scope.

Thomas

Greg Miller
13-Jul-2013, 11:44
I wouldn't bother... to much trouble... a waste of film... listen to the pessimistic critics... stay home and sleep!98727

Who here has said that??? Seem's to me like everyone is trying to help him get his shot.

polyglot
14-Jul-2013, 04:14
To be fair, with the abysmal reciprocity failure of that Foma, I doubt you'd have gotten anything on film anyway. I've had limited success with T-Max 100 and long exposure and it has better reciprocity.

I've never had dew on my lens, except when I would come out of a cool car into hot humid evening, at least here in the Deep South.

Actually it depends on what your foreground light is like. Stars are bright which means they are not very attenuated by the reciprocity failure of Fomapan, but the light pollution (quite a bit dimmer) is more-attenuated.

Ignoring reciprocity failure, light pollution is your limiting factor on star-trail exposure duration and therefore trail length. Since the stars move, the intensity of the star trails is mostly a function of aperture and film speed; the trails don't get brighter with more time though the light pollution does. So Fomapan can actually be a pretty good approach to star trail photography as it will make the trails stand out better and therefore you can obtain longer trails without light pollution washing them out.

But you're likely to lose all detail in your foreground compared to a a film (Acros, TMY2) that doesn't have severe reciprocity failure. Unless you flash-light it ;)

Corran
14-Jul-2013, 07:04
Do you have any Foma long exposures? I get where you are coming from but the stars vary in Magnitude, a lot. I think you'd be correct for the brightest stars like Sirius, Vega, etc., but most others will still be under the reciprocity line.

Go take a 1-second exposure on a digital camera at f/11, ISO100 tonight and I bet you'd see nothing on the screen save for a couple bright spots. This photo below was something like 2 seconds at f/2, ISO 1600 if I remember:

http://www.oceanstarproductions.com/photosharing/644_n.jpg

polyglot
14-Jul-2013, 16:59
Do you have any Foma long exposures? I get where you are coming from but the stars vary in Magnitude, a lot. I think you'd be correct for the brightest stars like Sirius, Vega, etc., but most others will still be under the reciprocity line.

Go take a 1-second exposure on a digital camera at f/11, ISO100 tonight and I bet you'd see nothing on the screen save for a couple bright spots. This photo below was something like 2 seconds at f/2, ISO 1600 if I remember:


Certainly the dimmer stars will disappear on Foma. But you probably only want the greatest-magnitude stars for trails, otherwise it will be a very busy picture (like dirty windscreen-wipers), no? I guess that's a matter of taste. If you want to see every possible star, I would recommend TMY2 on a very clear (no light pollution) night.

How awesome would it be if we could get RXP (Provia 400X) in sheets!?

Corran
14-Jul-2013, 17:27
RXP (Provia 400X) in sheets!?

That would be pretty awesome! Personally, I do want to see a lot of stars, even with trails. To each his own. More importantly though - test, test, test!