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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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I know light pollution will fog the film on a long exposure, but how will I know how long is too long?
I have an f/6 scope, and I cannot make out the stars in the little dipper, but I can see polaris naked eye in my back yard.
I polar aligned my scope in the back yard with the best results so far, so I'm leaving the mount set up all week.
I've been getting better at guiding, so I've been trying prime focus for anywhere between 10 minutes to 25 minutes.
I do this every night until 1:00 am, and I have to be at work by 6:00 am. I'd like to know if I should keep trying, or just go to bed at decent hour.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
Edited by tommyhawk13 (12/05/07 05:31 PM)
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ClownFish
Post Laureate
Reged: 04/26/05
Posts: 5600
Loc: Islamabad, Pakistan
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What film?
CF
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Learn all about POLAR ALIGNMENT with my Drift Method Tutorial and simulator!! Or visit my Foreign Service Blog!
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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Kodak E200. I should mention that the North is by far the worst, I have a Super Walmart 6 blocks to the North, and Downtown Jacksonville is to the Northeast. The zenith to the eqitorial belt are by far the best views.
I can make out Lyra easily naked eye Praepse (sp?), and Sometimes I swear I can barely make out M31. The light pollution map in Skyclock says limiting mag is 5.5. I'm in the red, but close to the orange zone.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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JBull
sage
Reged: 10/10/05
Posts: 401
Loc: Dallas, TX
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I'm just throwing an educated guess out there but at f/6 under your described conditions I would expose about 15 minutes max on a moonless night. An advanced technique to beat the light pollution is to expose many 5-minute images and stack them to increase signal-to-noise ratio. This is commonly done with digital cameras but applies to film as well. I think you're not wasting your time practicing polar alignment and guiding. Getting to a darker site is the best solution and have your skills ready for those special nights when the milky way and faint objects are crisp and clear.
I live in between Dallas and Ft Worth and the light pollution is awful. My solution for light pollution has been to pack my scope and travel to a state park about 70 miles away in a light pollution blue zone. It can be very frustrating to get to the perfect spot on a clear night and struggle with alignment, tracking and focus and all the things that get better with practice.
In the meantime you can get some nice images under light polluted skies by picking the right targets and exposing the right amount of time. Orion nebula, M13, double cluster, other object with good brightness relative to the background of light pollution.
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Jeff Bullard
Dallas, TX
Check observing forecast for astronomers anywhere in the world:
http://astroforecast.org:8080
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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I took a leap of faith last night and shot M31 at 30 minutes. It was just a hair West of zenith when I started, so it was in a dark part of the sky. I guess I'll know for sure when the film is processed.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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jrw11
professor emeritus
Reged: 06/09/07
Posts: 501
Loc: U.S.A.
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Good luck!
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Celestron C6n -HD Reflector
dual axis drive motors added
Orion 80mm Short tube refractor
Skyscout
Early 70's Pentax 7x50
Garrett Optical 12x60
Garrett Optical 15x70
Oberwerk 20x80 Standards
Canon Rebel Ti (film)
4 Minolta Srt cameras
Mamiya RB67 Pro-s with 180 lens
127mm KL lens for RB, Bellows hood for RB67
120 and 220 film backs
Cambo SCII 4x5 view camera
over 50 other film cameras
several eyepieces
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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This is what 15 minutes gives me.
Be kind, it's my first DSO at prime focus.
Kodak E200
8" f/6 1220mm reflector
Manually guided with a very under powered 60mm Meade refractor.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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Nightfly
super member
Reged: 06/20/07
Posts: 199
Loc: Sullivan, Maine
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Better than my first prime focus. You should be encouraged! Crank up your guiding power and try again. Good luck!
Jim
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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I just received an Orion Guidescope, and That woll probably max out my mount. This was by far the best guided shot on the roll. The ep was a 25mm MA with a diy reticle, barlowed, and the "guidescope" was 700mm. I calculated that to be about 2x the imaging scope.
the new scoep is 900mm, and it came with a 12mm ill. ret. I'll barlow that as well, and it should be a lot better. The double crosshairs are a lot closer than mine are too.
Aside from this roll being ruined by light leaks, it did give me lots of useful information.
I found out how tight the guiding tolerances are, how little I can shoot in my yard, and it gave me a good idea at how my polar alignment was.
I'm not looking at this roll as a loss at all, but just another step.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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JBull
sage
Reged: 10/10/05
Posts: 401
Loc: Dallas, TX
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Thats pretty good. A little guiding error but thats ok it still looks nice. What did you find about exposure limit with the light pollution?
I also made a reticle for a 10mm eyepiece when I first started out. The hardest part was positioning the crosshairs so that they would be in-focus when looking through the EP. That Orion scope with illuminated reticle should help a lot.
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Jeff Bullard
Dallas, TX
Check observing forecast for astronomers anywhere in the world:
http://astroforecast.org:8080
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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This is a 30 minute exposure, the longest I attempted. It's unprocessed, and the dreaded light leak is not cropped out of this one.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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ClownFish
Post Laureate
Reged: 04/26/05
Posts: 5600
Loc: Islamabad, Pakistan
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Good job so far Tommy! You'll do better with each attempt.
That light leak is a serious problem. I really wouldn't waste much more film until you either fix it, or get a better camera. I suspect you're using a modern camera with perhaps some illuminated display or lights? I would seriously consider a fully manual camera, such as an old Olympus OM-1, Nikon F2, Pentax K1000 - these can be found on eBay for not much money. f you are using one of those old cameras, then the seals need to be replaced. I just re-did mine after 23 years.
Your photos also appear slightly out of focus. As you may have read here before, this is NOT an easy thing to do. You really need a focusing aid.
CF
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Learn all about POLAR ALIGNMENT with my Drift Method Tutorial and simulator!! Or visit my Foreign Service Blog!
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tommyhawk13
sage
Reged: 09/28/07
Posts: 492
Loc: Jacksonville, Fl
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It's an old model, and the battery wasn't even in the camera. The light meter does have a dim led, but since the light meter & flash functions weren't needed...
The red streak is all light leak. Luckily, I've found a kit on eBay for $8.00 from Japan.
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Meade Starfinder 8,Meade SN-8 OTA, Orion Atlas, and a handfull of film cameras
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