How to use Aperture Priority for loooooong exposure?

Hi,
I've heard that Nikon FE/2 and F3 are well known to be capable of giving an extra long exposure, i.e. leaving it on AE for star trails and getting 2-3 hours of exposure. My question is how does it deal with reciprocity failure? Do you guys give extra + compensation? What are the tricks?

I have just begun experimenting with star trails myself (8hours bulb mode) and have conducted extra long exposure (1 hour) aperture priority AE with my F3, FA, FE2, FM3A & FG so I this is still new to me. From the very few star trails tests I've conducted, I believe my ideal setting using ISO100 slide film is f8 with bulb mode but more importantly well outside city - or any other artificial lighting, and obviously clear starry night. I also think there should be no moon in the frame at anytime. This is my first attempt taken with ISO50 Velvia, f2.8 from my back porch (city lites, neighbor porch light) and the big white line is the moon coming into frame. This started at 9pm and I ended the exposure about 5:30am with the moon coming in past midway of the time. I am thinking well outside the city, the rest of the frame would be near black and only the star trails will show up white. My next few attempts were worst - and not interesting, due to weather and still not outside the stray light zone!



Extra long exposure AE is not the same as in this case, there will be enough light in the frame to trigger the meter after some extended period of time. I have conducted controlled light setup of up to 2 hours and these long periods are not accounted for by the film's data sheets as usually it only shows compensation for seconds worth and not any longer. In both cases below, there was enough accumulated light to allow the camera to get "proper exposure" and I really didn't know how the waves would look leaving the shutter open for that long. This was taken with Fuji 100 C41.



Anyway, I believe these are two different applications and you'll have to try it anyway as these extremes are not usually accounted for in data sheets.

I can’t see a reason to use aperture priority for star-trail shots unless you have an illuminated subject in the foreground for which you want a ‘proper’ exposure.

You can, however, use either body without battery power to shoot trails. A cable release is required for the FE2 when using ‘B’ (bulb mode) on the shutter speed dial. On the F3 you can do the same – cable release in bulb mode. Or you can accomplish the same (long exposure) on the F3 without a cable. The drill, after removing any filters, mounting on tripod, focusing, composing, setting aperture: 1) set power switch under film advance lever to ‘off’ position, 2) close viewfinder curtain, 3) shutter speed dial set to ‘T’, 4) turn manual shutter release button (under DOF preview button) from 12 o’clock position to 10 o’clock ‘ready’ or stand-off position, 5) using an object such as a baseball hat or equivalent and with one hand, totally obstruct the front element without touching the lens/camera, 5) trip the shutter using the manual release lever, remove hand from camera, 6) wait a half second for vibration to stop, 7) remove baseball hat from front of lens, 8) wait several hours while enjoying your beverage of choice (critical step…don’t blow it), 9) obstruct front element with hat, 10) turn shutter speed dial to ‘B’ or ‘X’ to close shutter. Keep in mind that dew may settle on your front element so you may want to consider how to combat it.

If using a cable release, firmly secure the cable/finger plunger to the camera to keep it from swinging or being jostled by even a slight breeze.

Les, are you saying aperture priority kept the shutters open for one hour in all those cameras you listed? Whoa! I didn't think that was possible given their low-end metering range of EV 1. You didn't go overboard on my Step #8 above, now did you?

Aja B said:

I can’t see a reason to use aperture priority for star-trail shots unless you have an illuminated subject in the foreground for which you want a ‘proper’ exposure.

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Sorry, star trails may not be the correct example. I meant for object that we want to exposed as 18% grey, for example moonlit landscapes.

Meters cannot account for failed reciprocity. If you insist on using AE for these shots, you'll have to covert your data on reciprocity loss into EI changes instead of time extensions or aperture changes. Then again, unless the meter can tell you how long it plans on exposing the film ahead of time, this is not possible. Is there a camera meter that can display a time longer than 30 sec? Manual will server you far better IMO.

Aja B said:

8) wait several hours while enjoying your beverage of choice (critical step…don’t blow it)
Les, are you saying aperture priority kept the shutters open for one hour in all those cameras you listed? Whoa! I didn't think that was possible given their low-end metering range of EV 1. You didn't go overboard on my Step #8 above, now did you?

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In the tests I conducted, all of these made very long exposure of more then an hour in the controlled lighting I provided. From much shorter exposure times, the FG consistently terminated exposure well before the others. I also exposed some C41 film in these and they came out perfectly exposed.

I haven't found a device or figured a way of accurately timing such long exposures so I can see where step #8 can be a problem . . .

MFstooges said:

Sorry, star trails may not be the correct example. I meant for object that we want to exposed as 18% grey, for example moonlit landscapes.

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These Nikons will determine exposure at the time of shutter firing and may successfully take very long exposures. Just exactly how long I have not qualified although I have done more then an hour. I am not aware of a handheld meter that can perform this metering to test just how accurately these are. Of course a potential problem here is if the exposure time calculated extends it past dawn in which case it will result in overexposure. Of all the aperture priority AE cameras I have tested, the only camera that can account for changes in scene lighting during extended exposure would be those that are equipped with off the film metering and those are the Olympus OM-2 & OM-4 and the Pentax LX. I don't have the OM-2 (I have the OM-2N) which I understand can meter for as long as it takes to get a correct exposure but the Pentax LX will.

None of the cameras would do an AE exposure accurately for such a long exposure time. Although some cameras would have the shutter open for a long time but it by no mean accurate. The light level is well below the metering range. The shutter time is well longer than the designed shutter speed range. Reciprocity failure is not taken into account.
If you get good result it's just luck.

When results are repeatable it is no longer luck. It may be luck that the cameras I have tested have repeatable results since these are well outside their specs so YMMV.

I am particularly interested in aperture priority AE for very long exposures and to that end I did test the following:

1. Canon - A-1, AE-1P, Elan 7, EOS-1V, EOS-3 - all stop at 30 seconds
2. Minolta - X-700, XD-11, XE-7, XK - anywhere from 8 to 25 seconds
3. Nikon - F3, FA, FE-2, FG, FM3A - more than an hour
4. Olympus - OM-2N, OM-4T - off the film but ends at 3 minutes
5. Pentax - ES II, K2, LX, ME Super, Super Program - LX has off the film and hours long

For full disclosure, I conducted the tests as follows:

1. Setup continuous daylight balanced light and verified with Sekonic 758 a proper 1 second exposure on gray card
2. Qualify metering at 1, 5, 30 seconds
3. Qualify metering at 1, 5, 30 minutes
4. Tested more then an hour on F3, FA and LX with C41

Again these are using only my own seemingly fully functional cameras. I don't know if this applies to all of the same models. Repeatable results in the setup and I have more than a handful of repeatable results on C41.

These are some results I got from my controlled very long aperture priority AE exposure with Kodak Gold 100. These are unretouched straight-up neutral scans. Background and base are white foam core boards so you can easily adjust colors as needed. Of course this film has so much latitude that meter can be off by -2 or +6 stops and still be automatically recovered with no problems so I should try it with slide film.




Link to larger version -> Gold 100 long exposures.jpg

FWIW The Luna Pro's calculator goes to 8hrs. Accurate? At least as a SWAG.

Les Sarile said:

These are some results I got from my controlled very long aperture priority AE exposure with Kodak Gold 100. These are unretouched straight-up neutral scans. Background and base are white foam core boards so you can easily adjust colors as needed. Of course this film has so much latitude that meter can be off by -2 or +6 stops and still be automatically recovered with no problems so I should try it with slide film.

Link to larger version -> Gold 100 long exposures.jpg

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Thank you for the post Les, that confirms what I heard and read. At least for negative film.
Have you done color correction on your samples? I was thinking it may cause color shift.

MFstooges said:

Have you done color correction on your samples? I was thinking it may cause color shift.

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All my scans from the Coolscan are neutral - all color settings off, with no pre or post anything.

When you hit reciprocity failure, the exposure becomes a function of how an individual emulsion responds, so what may work with one emulsion may not work with another. IME building a knowledge base with bulb exposures is the way to go. Les Sarile's test is very impressive, but it isn't a sky scape. Also, depending on subject and emulsuion, you may get an expansion effect, because some parts fail and others don't, particularly if your exposure times/exposure levels for some parts of the comp fall somewhere near the point of failure. For star trails with a dark sky you probably aren't seeing much effect because the dark part isn't exposing enough to fail, and the stars are exposing plenty while they track through the frame. Using AE probably isn't going to trip the shutter until enough photons have added up to wash out the sky, what the camera would see as a proper middle of the road exposure, so works great for the bridge shot and the crayons but not as well for something when you want the predominant part of the composition to be black, or at least dark sky. I used to paint foreground objects with a flashlight, and sometimes it worked out pretty cool. If you have a somewhat light polluted sky reciprocity failure is your friend, helping to hold back the sky while the brighter stars expose, but of course some of this is negated by the stars being apparently dimmer, and dimmer stars being drowned out all together. All in all light pollution sucks, destroys the night sky for astronomers, photographers, and lovers alike, wastes energy on a vast scale, and should be seriously against the law. Ask me about my real opinion on it sometime. I have noodled using a filter that blocks the wavelengths common to city light so I can shoot from my current location, but I haven't noodled what that filter/s might be. One thing I can tell you is that you will likely be amazed at the difference a truly dark sky can bring out, and beyond having no moon in the frame, having no moon in the sky at all can bring out several magnitudes more of stars. In my experience if you have a truly dark sky, you almost can't screw it up. (and if someone could, that would be me)

If you are feeling particularly exotic you can hyper your film: http://www.astropix.com/HTML/I_ASTROP/FILM/HYPERING.HTM

I think I still have some hypering junk laying around somewhere.

Nowadays I use the imaging technique that shall not be mentioned for my astrophotography. Funny this thread has come up, I've just started getting back in to it. I have been thinking of piggy backing on of my fim cameras onto my EQ mount and doing some wide field MilkyWay exposures, but I'll have to get a ways out of town for that.