Digital NLC Photography

[tmcewan]

Hi all,

I've just realised that there are no digital photography exposure or technique recommendations on any of the NLC observing guides. The settings I've been using on my Canon 350D are:

200ISO, manual focus, 6 sec exposure on shutter priority setting.

If I use the intervalometer then I set a 4 sec gap between exposures, giving 1 shot every 10 secs. These settings do cover most situations but I've noticed that local midnight exposures can be slightly under exposed (my max lens aperture is f3.5).

What settings do you use? It would be useful to have recommendations for the observing notes.

Tom

[PeteG]

I use a Pentax Ist Dl DSLR with an 18-55mm lens
If I use auto settings I set it on Sports mode.
This chooses the widest aperture and the fastest shutter speed available.
I auto bracket every shot at one exposure intervals.
If I use the B setting (when it's very dark) I time exposures at 3 seconds, 5 seconds and 10 seconds then preview to see which appears best.
A sturdy tripod and a cable release is a must.
A lens cleaning cloth is essential as the lens can fog up quickly without you noticing.
Check the lens every few minutes and also check the focus regularly if you have it set to manual.
It is easy to knock the camera and the focus can shift without you noticing..

Take spare batteries and a spare Flash card...
PeteG

[tmcewan]

Hi,

I think what I'm looking for here is a general exposure setting; a good starting point for inexperienced observers to use on moderate to bright NLC. The old film photography advice was to use 200ISO slide film with exposures of 4-6 seconds, f2.8 (or thereabouts), bracketing 1-2 stops. This now needs updating as most observers have moved on to digital.

Tom

[PeteG]

well the BIG advantage these days Tom is being able to take 1,000's of images and review them instantly without a hefty processing fee.
All cameras behave differently and you have to learn what your camera can and cannot do.
Even handheld compact cameras can produce amazing results (see the link to Brian Mays photo today)
I don't think there can be any hard and fast rule for taking photos of NLC's.
The results coming in on this forum this year have been astonishing!
Well done to everyone, and to anyone who thinks their work isn't good enough post it anyway.
There are some very friendly people here who can advise and help you improve your technique.
Keep on snapping....
Pete

[tmcewan]

I think we can agree on the basic advice of using a sturdy tripod, exposing on the NLC and previewing results then adjusting exposure, if necessary. I'd also recommend that an observer should aim at keeping exposure duration as short as possible in order to avoid the NLC trailing. The aim here would be to accurately record NLC structure, I'm not concerned with pictorial or aesthetic considerations.

I know that there are a lot of variables to deal with. I already have some information to work with, based on the settings used on automatic camera stations (once set-up, these settings don't change over the season). In fact, that may be a better way to approach this; if you were to set up an automatic system, what settings would you apply to the camera? Remembering that this has to cope, as best as it is able to, with the full range of illumination conditions experienced across the season.


Options:

ISO?

Focus, manual or automatic?

Metering, manual or automatic?
If manual, lens aperture and shutter setting?
If automatic, then full auto or use of shutter or aperture priority?

[leolion]

I find that 400 ISO , 4 seconds , f 2.8 works OK for me at a focal length equivalent to 38mm on a 'steam film camera'. Yes, I still use film but not for NLC . It is easy and sensible to shoot and review . I will occasionally use a telephoto approach on some NLC detail . This is the time to bracket. The above setting I have also found is a great starting point for aurora ( we need a CME !!)
Many of the images you receive of digital origin should have the Exif information available as a 'passenger' which you could 'milk' for information. IrfanView does this easily with a couple of clicks
I keep my camera clock on GMT/UT year round and do occasional checks to see if any adjustment is needed. I photograph one of my 'radio-linked' watches and can cross check / record the error twixt Exif time record for the exposure and the watch display image!

[PeteG]

also, if you don't have a tripod and cable release place the camera on a hard surface and use the timer to release the shutter.
Pete

[johnmason]

Good info in this thread for someone like me with relatively limited experience of night photography!

On my Nikon I can go up to ISO 3200 but it gets a bit noisy: ISO 1000-1600 doesn't seem too bad though. The problem I've had this year is that each display has featured tropospheric clouds moving along quite briskly and all sorts of horrible motion-blur occurs with these. The best results in such situations seem to be right at the end of the display, as dawn is just about to break.

I've just worked out how to set the Nikon to self-timer. The manual makes some novel look decidedly rakish! With the Canon A-1 I used to use I shot a few noctis on self-timer with the camera sat on a bean-bag (a knotted pillow-case full of birdseed) - a bit of a thing to lug about but you can plonk it on top of any fencepost, stone wall etc etc etc and you have an instant tripod!

Cheers - John

[André]

I think all the important things are said here. The only thing I want to add is the rule "expose to the right", which means always expose the image as bright as possible without loosing the lights. Most digital cameras have the flashing lights display option as well as a histogramm. The Histogram should be as far right (hence the name) as possible without touching the very edge. You can always darken the image with minor loss. If you try to brighten the image you will just enhance the noise.
What I used recently on my Nikon D90 was a 18 - 70 mm/ 3.5 - 4.5 objective. Usually at apperture 5.6, 5 - 30s exposure at Iso 200. I used the same settings with my D70. With my old Powershot A60 and A95 I used 15s at 2.8 and Iso 100 - 200.
Tripod, remote/self timer and mirror lock-up (if possible) are a obiously necessary!

André

[markt]

Good tips all of you! I can only back up what everybody has said already

[johnmason]

Thanks again - all things to consider and practice - prior to fumbling about in the dark and wishing I had rehearsed a bit!!

Cheers - John

[johnm]

The other thing to consider is what the colour temperature should be.

A low colour temperature reduces the red response and enhances the blue. This will tend to reduce the colour of orange light pollution clouds to near grey.

A high colour temperature will reduce the blue response and may therefore decrease the contrast of NLC.

Anyone tried different colour temperatures or do you just let the camera decide by just leaving it on Automatic White Balance ?