Night shooting problems

[cowcrzy06]

Hello all!

To some of you this may seem to be an easy question.When I set out to try this I did not think it would be such a hard task. We have a large amount of fireflies in our pasture right after sundown. The longer you wait after sunset the less there is. My Idea was to take a photograph where the fireflies would leave all sorts of yellow streaks in the picture. seems simple right? Well when you do this too soon after sunset there is still too much light in the sky and you cannot see the fireflies because the shutter speed was too slow and it let in too much light. It made the sky look brighter than it was. There is a 1/4 moon also. So I waited about 30 minutes and came back outside. Now there was not many fireflies but I thought that if the shutter remained open long enough that it would catch the few that were left. needless to say I just could not get any good results. So my camera is a Canon EOS Rebel Xti. Is there anyone who can help me with this by suggesting how I should set my camera? I know I must be doing something wrong but what it is I do not know.This is really getting on my nerves and driving me batty! Oh, and as usual THANK YOU! in advance!

[devilgas]

Re: Night shooting problems

as the fireflies are relatively dim, you will need to open the aperture as wide as it will go and maybe even increase the iso setting. the downside is that the shutter speeds will become faster, so it's a case of balancing everything out. in this instance though, your settings are dictated by the brightness of the subject and how fast they move.
do you have the possibility of shooting the fireflies against a naturally dark background? e.g. a wooden shed, a copse of trees etc.
it's similar with taking shots of star trails. a wide aperture will allow the fainter stars to be picked up, but also increases the light pollution captured. a smaller aperture reduces the light pollution but then also doesn't capture the fainter stars.
your light pollution in this case is moonshine / remnants of the day.

[Ian]

Re: Night shooting problems

as the fireflies are relatively dim, you will need to open the aperture as wide as it will go and maybe even increase the iso setting. the downside is that the shutter speeds will become faster, so it's a case of balancing everything out. in this instance though, your settings are dictated by the brightness of the subject and how fast they move.
do you have the possibility of shooting the fireflies against a naturally dark background? e.g. a wooden shed, a copse of trees etc.
it's similar with taking shots of star trails. a wide aperture will allow the fainter stars to be picked up, but also increases the light pollution captured. a smaller aperture reduces the light pollution but then also doesn't capture the fainter stars.
your light pollution in this case is moonshine / remnants of the day.

Erm - not sure I followed that

The exposure will be the same if you increase the aperture size and increase the shutter speed (if the camera is on auto, for example). One compensates for the other to maintain the same exposure value. A shorter shutter speed will mean shorter star trails or none at all, but the light pollution will be just the same if the exposure value remains the same.

The problem with fireflies is that they are incredibly dim. You need to up the sensitivity of the camera and the exposure value in order to capture the glow, but the much brighter, in relative terms, sky, will be bleached out. The dynamic range that the camera has to cover is just too much for a single exposure. Your eye (or more accurately, your brain) does a magic job of dynamically compensating so your first hand experience is 'normal' with a nice sky and nice fireflies, but in reality you just don't realise your brain is doing all that compensation.

The only solution I can think of is to bracket the exposure widely, using a tripod to keep the scene framing identical, and then to combine the images using selective layers or high dynamic range features, like HDR in Photoshop CS2/CS3.

Or, forget about the sky or other sources of relatively bright light and exclude them from the composition.

I'm so envious you have fireflies! I used to spend summers in central France in the wilderness and have fond memories of firefly spotting in the evenings (intensifed by the cheap local wine of course!) plus lying in the lanes looking up at the pollution-free sky and seeing the Milky Way

Ian

[cowcrzy06]

Re: Night shooting problems

Ian,

I cannot imagine moving back to the city and missing all those stars in the sky. On a dark night without the moonlight you can clearly see the milky way and it is soooo beautiful! Until I moved to the country I had no idea there were so many fireflies! This is why I want to capture it but with streaks and slow shutter speeds.

[devilgas]

Re: Night shooting problems

should've explained it better.

you'll need to expose for the fireflies. the speed at which they move AND their relative brightness dictates how wide open the aperture will need to be and what level you'll need to boost the ISO to. i don't know how bright (or dim) they are, but i'm assuming you'll need to open the aperture as wide as it will go. the shutter speed will then be dictated by how much ambient light you want in the picture. if it's dark, then there's no issues. if it's still pretty light then the shutter speed becomes a factor.

of course, you could use a slower shutter speed, and then close the aperture a bit to balance it out, however you may then not see the fireflies as they may be moving too quickly for the light given off by them to be picked up by the camera.

if ambient light is unavoidable, try shooting against a dark background rather than open sky - you can gain a longer shutter speed for free.

aperture will be king though. start wide open and stop down as necessary or, more likely, increase the ISO value.