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Star trails and Perseids

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#1 khingdheano

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Posted 09 August 2019 - 05:28 PM

Greetings!

I'm going to set an Asahi Pentax Spotmatic on a tripod tomorrow night after the moon sets, and try to catch some Perseids. I'll be using a 28mm lens at f/2.8. Will be shooting color, I have some 400 speed film, and also some 800. I plan on leaving the shutter open for maybe 4 hours. Which would you use? I'll be at a dark sky site, but I think the faster film would pick up more sky glow (there is a town about 30 miles away). So asking for suggestions. There is a camera store near me that still stocks film (!) so if other speeds are suggested, I could get something else.

I would appreciate opinions!

 

Regards,

K. Dheano



#2 Ken Watts

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Posted 09 August 2019 - 05:47 PM

I do not remember how to calculate it, but, be careful about fogging of the film.  Maybe an astrophotographer working in film can help...


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#3 ShaulaB

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Posted 09 August 2019 - 06:25 PM

The Moon will be a significant source of light pollution for this year's Perseid meteor shower.



#4 JGass

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Posted 09 August 2019 - 06:40 PM

Will the camera’s battery last during the exposure, or does that only power the meter?

#5 khingdheano

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Posted 09 August 2019 - 06:52 PM

Completely mechanical shutter, battery is not an issue. That is for the meter only, but I have never installed one.

 

Will the camera’s battery last during the exposure, or does that only power the meter?



#6 khingdheano

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Posted 09 August 2019 - 06:54 PM

Hence why I am waiting until moonset to shoot.

 

The Moon will be a significant source of light pollution for this year's Perseid meteor shower.



#7 Michal1

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Posted 10 August 2019 - 07:58 AM

Exposure times are generally hard to advice because different places have different light pollution and different films have different reciprocity failure. For your guidance, my standard for widefield astrophotography is 45 min at f/4, 200 ASA film with low reciprocity failure. 60 min at these setting would be a somewhat overexposed but still fine. Your 400 ASA would probably have a higher reciprocity failure and might be less sensitive to the sky glow in the result but that is hard to guess. If you insist on a 4 hour exposure, I would try f/8. But this will limit you just to bright meteors. I would personally stick with my favorite settings, 45 min at f/4, even with your faster film.

Here you can get some idea about the length of the star trails:

https://www.astro.cz...Praktica 35 mm/

Remember that the length also depends on the declination of the photographed star, the sky moves faster near the celestial equator than near the pole. If you have more time, you can search the galleries of the others:

https://www.cloudyni...aphy-galleries/

I don't remember any particular link that I could give you.

 

Good luck and share your results with us, I will be curious!


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#8 khingdheano

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Posted 10 August 2019 - 10:30 AM

Thank you, sir! Will follow your advice. I'll shoot some frames at 45 min f/4 on 200, then might try some longer exposures.

 

 

Exposure times are generally hard to advice because different places have different light pollution and different films have different reciprocity failure. For your guidance, my standard for widefield astrophotography is 45 min at f/4, 200 ASA film with low reciprocity failure. 60 min at these setting would be a somewhat overexposed but still fine. Your 400 ASA would probably have a higher reciprocity failure and might be less sensitive to the sky glow in the result but that is hard to guess. If you insist on a 4 hour exposure, I would try f/8. But this will limit you just to bright meteors. I would personally stick with my favorite settings, 45 min at f/4, even with your faster film.

Here you can get some idea about the length of the star trails:

https://www.astro.cz...Praktica 35 mm/

Remember that the length also depends on the declination of the photographed star, the sky moves faster near the celestial equator than near the pole. If you have more time, you can search the galleries of the others:

https://www.cloudyni...aphy-galleries/

I don't remember any particular link that I could give you.

 

Good luck and share your results with us, I will be curious!



#9 canondslr

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Posted 10 August 2019 - 06:04 PM

I’m going to take a guess here.  Although films like E200, and Provia100, are known to work nicely for long exposure astrophotography, shooting Star trails combined with meteors might work better with a higher speed film? It may all come down to how the sky glow registers over time on film. 

 

For example, if you’re shooting a very long tracking shot of Orion with Provia 100, as far as collecting light goes, it should quickly over take most 400 speed films after just a few minutes due to big differences in reciprocity failure.  But maybe real world photographs prove otherwise?  Either way, a meteor is very short-lived, and a higher speed film might capture it better than a slower speed film.  And if the shutter stays open for several hours , maybe the sky glows cumulative affect falls short of a slower film that has less reciprocity failure?   So maybe a higher speed film would win at both capturing meteors, and reducing skyglow on long exposures. Again, I’m not sure if this actually holds true. Haha. Hopefully someone can answer this. 

 

I may do a side by side test in the future. I’m really curious now! 

 

Good luck in your adventure!



#10 Michal1

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Posted 10 August 2019 - 07:09 PM

So maybe a higher speed film would win at both capturing meteors, and reducing skyglow on long exposures.

In theory yes. But the high speed films I used came out with a rather bright background. Maybe I was using too long exposure times or the light pollution was worse or whatever. I don't know. It was many years ago. I would definitely like to see a side-by-side comparison.



#11 canondslr

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Posted 10 August 2019 - 07:54 PM

Thanks Michal

 

A 2 or 3 hour star trails test with Portra 400 and the new Ektachrome 100 might be fun to try! 

 

Tom




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