Star trail with slide film

<p>I am going to have my own trip to East area in USA. I have Pentax 67 and Me super but Pentax 67 will be my main camera for start trail and astro photography. I tried shooting astro images few years every July or August with my digital camera. Well using the film camera with long exposure will be much better than using the digital camera.</p>

<p>I already made battery eliminator part for Pentax 67 and all I need to do is to shoot pics at night. But I have few concerns about exposure, aperture, film, and more.</p>

<p>How should I calculate the exposure base on the aperture?<br>

Provia 100f is what I'm going to use but how can I calculate the reciprocity failure?</p>

 

<p>Are you sure that film will be better than digital? With digital you can combine images, with film you have to be right every time. <br>

Google is your friend with regard to finding basic settings; you may even find a turorial on photo.net :-)<br>

I don't think reciprocity plays a real role in this. You may use it to your advantage though since the sky won't lighten us as much as in digital due to the reciprocity factor. But why not take a few test shots with digital in order to get the right settings?</p>

<p>I have 5 years old digital camera and batteries die quickly within an hour. Cant use it for this time.</p>

<p>I don't rely on google that much. </p>

<p>You would be well advised to at least look thru the results others have obtained to establish where you want to begin. One source, a contributor to Lunar landscape, suggests the following formula for determining the reciprocity factor for Provia 100F for exposures longer than 120 seconds (data was based on manufacturer curves as modified by his densitometer readings from his real life testing, and he noted that different film batches did show differences in results) : for indicated exposure times above 128 seconds: <br /> factor = 1 + 1.0165E-06 * (t-128)^2 where t = indicated exposure time in seconds.</p>

<p>As far as determining exposure based on aperture, normal relationships apply. I've occasionally used th New Jiffy Calculator, which advises the following: Line up film speed at Scene 26, and then convert shutter speeds to time exposures as follows: seconds become minutes and minutes become hours. </p>

<p>It's easier than you think with mechanical film cameras. I have done it several times on 35mm film with old Nikons. For ISO 100 film f5.6 is good for several hours, f4 is better for 1-3 hour exposures. A wide or super wide angle lens is my preference. Light pollution is worse than you expect because small amounts creep into the frame over the long exposures. Try to avoid it as much as you can. A solid tripod (hanging weights on the tripod helps a lot) and taping the lens at infinity helps. Lock the shutter button with a cable release. </p>

<p>A foreground terrestrial feature can help. Having the North Star in the frame gives dramatic circular star trails. I have done exposures up to 8 hours to get very long 120 degree arcs on the sky. Only one photo is possible per night per camera. Set an alarm clock if you plan to sleep. I have awakened after dawn and ruined a few shots. Clear nights will leave dew on your lens, another detail to check periodically during the night. </p>

<p>The long time exposures cause unpredictable color shifts. Fujichrome can get an overall green cast. I prefer Ektachrome for that reason. Experiment and have fun. </p>

<p>I still don't get it. Both shutter speed and aperture control the brightness. If I expose the film too much, than it will be too bright, if I expose the film less, then it will be too dark. How am I suppose to know about the shutter speed? </p>

<p>The night sky light levels are so very low. And the extreme film reciprocity failure works in your favor by not being overexposed over several hours. Try it once and see.<br>

Go to Google images and enter star trails film photography. This I did was with ISO 100 slide film.<br>

http://www.photo.net/photo/3758930</p>

<p> </p>

<p>Ben - You are way over thinking this. Shutter speed? Sort of a non factor if you are doing a 3 hour exposure. Reciprocity? Don't worry about it. Nothing you can do about it. As above, try f5.6 for a couple of hours. Be sure that you are not in light polluted area, and that the moon is not a factor. Bottom line - the chances of get perfect the first time are slim. Experiment! That's fun of it. </p>

The only thing the shutter does is determine the length of the star trails. Ten minute exposure equals short star trails; 5 hour exposure equals long star trails. If you live in an area where there is a lot of light pollution then the sky will be very light after long exposures. Reciprocity failure may then prevent any more fogging of the film by the sky so it won't burn out. In this instance reciprocity failure is your friend.I would try f/2.8 for one hour shutter open just to see what happens.

<p>What if I use F4~8? Double the exposure or?</p>

<p>My 2c. It is very dark out there just try to experiment. The 1 stop etc won't matter much. </p>

<p>Digital - With the few astro type I have done with a pro here where he gathered many people on FB, the general setting for the milky way galaxies was like ISO 3200, F2.8 but I had a F3.5 only and 30 seconds. Some used a bit higher ISO, others used lower. With fireworks also. Kinda similar. Very black sky and very bright fireworks. </p>

<p>Slide film - I accidentally underexposed by one stop. I went to a pro lab and requested a test strip. They processed a snip of the film as normal so 1 stop underexposed, came out fine. </p>

The smaller the aperture the smaller the size of the lines of the star trails. Thin lines as opposed to thicker lines; the lengths would be the same. When talking exposure with star trails you are talking about time. "For these trails I gave a one hour exposure, for these trails, which are twice as long, I gave a two hour exposure."

 

Milky Way galaxies? We are in the Milky Way galaxy, about 1/3rd out from the center of the galaxy. The stars we see in the night sky are part of the Milky Way galaxy. The Andromeda galaxy is the next galaxy closest to us unless one includes the Magellanic Clouds. 30 seconds doesn't sound like one is trying to capture star trails but rather heavenly subjects such as the Andromeda galaxy or Horsehead nebula.

<p>http://www.brendandaveyphotography.com/?page_id=13</p>

<p>But the shutter speed still control the brightness. How am I suppose to know the exact aperture and shutter speed for 1 or 2hours of long exposure?</p>

<p>1 or 2 hours is the shutter speed. You set the film camera shutter to the B setting. With a cable release you lock the shutter open for the long duration. With film the exposure relationship with shutter speed and aperture is negated due to reciprocity (aperture/shutter speed relationship) failure during the very long exposures. The film's chemical sensitivity to light is not linear and strange effects happen. Slide film is a very different realm from digital. Experiment and discover for yourself. </p>

<p>So what Aperture? It will be various depend on Aperture and shutter speed. How am I suppose to know?</p>

<p>For starters, set your shutter speed to "B" for 2.5 hours. Lock with your cable release<br>

Aperture to f5.6<br>

Focus using the depth of field scale (infinity mark at the 5.6 engraving).<br>

Next night maybe go f8 for three hours. <br>

Take notes of all of your experiments.<br>

Results will depend on ambient light, atmospheric conditions, and temperature.<br>

Like I wrote before, you're not going to get <strong>your</strong> perfect results the first time.<br>

Remember, for ever great photo in the National Geographic, there were hundreds that were crap.</p>

<p> </p>

<p>I told you that google is your friend and that photo.net has a learning section: <br>

http://www.photo.net/learn/astro/star-streak<br>

http://www.photo.net/learning/photographing-star-trails/<br>

This will get you started. Since stars are direct sources of light that move relative to the camera/earth the shutter speed only influences the background (sky), not the star trails. Consider making a few test shots with a DSLR, if even for half an hour or so. It will give you extra information about the best settings for film. </p>

<p>And just for inspiration :-)<br>

http://www.dpreview.com/news/3295764960/put-a-stamp-on-it-the-astrophotography-of-matt-dieterich</p>

 

<p>I did star trails with my old Nikon many times, without much thought, and they always turned out well or at least decent. The important thing is: you need dark skies. I assume you will be visiting the east coast of the US, and in many areas the skies are much too light-polluted to get decent images. Ideally you want pitch-black skies, no moon, and no clouds. Then you are taking a picture of slowly moving point sources in front of darkness. Exposing for a longer amount of time will not make the star trail brighter, only longer. Opening the aperture will make them brighter, so will higher ISO film.<br>

As a starting point: I stitched 250 (digital) images in Photoshop. The individual exposure data for each frame was: ISO 1600, f/4, 20". So the total exposure time was about 90 min. The result is <a href="/photo/17882504">here</a>.<br>

So with slide film I'd open the aperture as far as possible, sit back and have a beer - or five. I haven't bought slide film in years, so I don't remember how bad film grain on high ISO film was, but you might try something more sensitive than Kodachrome 25 - ouch that dates me. :-)<br>

I'd be mostly worried about really dark skies. Maine, New Hampshire or Vermont might be your prime destinations. Here the skies are dark and humidity is low.<br>

Good luck!</p>

<p>Hi Benjamin, I did a lot of star trails with film (Velvia 100F) with a 35mm camera and Pentax 67II (which has a special mode for long exposures that do not drain the battery). If you wish to have some blue color in the sky with star trails, then start your exposure about an hour after the sunset, at the onset of nautical twilight. If you wish to have a dark sky, then you shall have to wait. I always used f/4 or f/5.6 focused at infinity and exposed for a maximum of one hour, but as mentioned above, if the sky is dark and there are no near light sources then you practically cannot overexpose even if you make a several hour exposure. The best way is to make a test yourself. A good idea is also look up how lightpaint some foreground for your star trails (<a href="/photo/13530112&size=lg">example</a>). Good luck!<br>

Best regards.<br>

Peter</p>

<p>Ben - Speaking of light painting (a great idea), do you have an off camera strobe?</p>