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long exposure help

sheriffwoody

Distinguished Member
i tried to take a long exposure shot of the ISS tonight as it flew over at dusk, but my camera wouldn't take the shot :(

i wanted it set to something like 10-20 seconds but everything i tried the camera tried to focus and then just said "nope, not gonna happen" and i missed the shot

was it just due to the lack of light? i was out on my balcony, 4 floors up, so not much light around me. i tried to include the lights in the horizon to provide the camera with a bit of light.

what am i doing wrong?

another question - if i have the camera set to f4 or f5.6 etc then it will tell me how long the shutter needs to be open for in order to get a correct exposure shot, so scroll left or right until the marker is in the middle and away you go.
is there a way of reversing this and instead of setting the f stop and then moving the exposure time around, can i set the exposure time at say 10 seconds and then be told what my f stop and/or ISO needs to be?

Thanks for any help
 

Ugg10

Distinguished Member
Focus on close to infinity and then set to manual focus to stop it re-focussing. As for setting, switch to shutter priority, auto ISO and then the aperture will sort itself out or just use manual plus ISO100 then set shutter and fiddle around with aperture until you get the exposure that you want.

Also, may be helpful if you let us know what camera/lens you have so help can be a bit more specific.
 

chum_2000_uk

Established Member
I've recently been trying my hand at some night time shots with my Nikon D5100. It's certainly not easy as you seem to have found out. My first few efforts turned out very poorly indeed, and I was just trying to photograph static-ish subjects such as boats down in Poole/ Sandbanks harbour.

My latest attempts have come out much better. I've been using a tripod (I'd say pretty much essential for night time work) and have also been using the self timer so that I'm not actually touching the shutter release. If a self timer is not ideal for the types of shots you want to get, then perhaps a remote may be a good idea?

Anyway, the last couple of shots I took came out really sharp and I was pretty pleased with the results. I also bracketed the shots; let the camera take three shots at different exposures, i.e. 0, -2 and +2 (but you can choose how big you want the gap in exposure values). The value in doing this is two-fold. One, you are more likely to get at least one decently exposed shot. Two, you have the potential to use all three exposures for HDR processing, which will allow you to extract more of the range of light from the scene.

Here are links to a couple of the night time pics I took down poole Harbour a little while ago:

Cargo Ships | Flickr - Photo Sharing!

Sunseeker | Flickr - Photo Sharing!

Those were both pretty long exposures, well actually three long exposures combined into one using HDR software for each pic, so that each part of the picture is correctly exposed.

I'd say another tip is to always shoot in RAW for night time photography. If you get a poorly exposed picture, but have shot in RAW you are much more likely to be able to salvage it in your chosen photoshop style package when you upload it to the computer. Remember though, if you shoot in RAW, no camera processing such as sharpening will be applied, so its always a good idea to give the pic a once over in photoshop or whatever to get the sharpness, contrast and exposure the way you like it.
 

sheriffwoody

Distinguished Member
thanks for the help guys, ran out and got this quick snap


any ideas how i could have made it look sharper? it was set to 15 seconds exposure.
 

chum_2000_uk

Established Member
any ideas how i could have made it look sharper? it was set to 15 seconds exposure.

Did you use a tripod? Also use self timer/ a remote so you're not touching the camera. Shoot in RAW then sharpen it using a photoshop style package.

What ISO did you use? Obviously you want to be using as low as you can get away with for the aperture and exposure time.
 

sheriffwoody

Distinguished Member
Did you use a tripod? Also use self timer/ a remote so you're not touching the camera. Shoot in RAW then sharpen it using a photoshop style package.

What ISO did you use? Obviously you want to be using as low as you can get away with for the aperture and exposure time.

Yep, used a tripod and used a 2 second timer, so had time to get my hand off the camera before it started taking the pic.

also, did as suggested, pressed the button to get it to focus automatically until it stopped and wouldn't take the photo, then switched to manual focus and took the shot.

had the ISO on auto i think - according to the details the ISO was at 250.

unfortunately i don't have any decent photo shop software - the best i have is paint.net

edit: just realised that photo was a 30 second exposure, not 15.
 

chum_2000_uk

Established Member
this photo was taken a bit earlier in the evening at 13second exposure and is a lot sharper

What was the aperture set at for this one? Obviously during night time photography to keep the exposure times down you either need to have the aperture wide open or the ISO up a bit. But, both of those things will mean you lose sharpness and add noise. Find out what the sweet spot is for your lens in terms of aperture; often around f8 or something like that and try to stick to that and then keep your ISO as low as you can.

Obviously make sure your tripod is rock steady and use as long of an exposure as you can for the shot you want. Other than that... I'm sure the guys on some of the photography forums can offer you loads of good advice. My experience is limited to the few sets I've done and started to learn from I'm afraid.
 

sheriffwoody

Distinguished Member
the second photo was at f5.6
the photo of the ISS was at f3.5

for the ISS shot i had it in shutter priority, so i chose how long i wanted it open for and the camera set the fstop itself
 

chum_2000_uk

Established Member
the second photo was at f5.6
the photo of the ISS was at f3.5

for the ISS shot i had it in shutter priority, so i chose how long i wanted it open for and the camera set the fstop itself

I'd personally be more inclined to shoot in aperture priority on the sweet spot of the lens and let the camera decide how long to expose for. That's what I did with the pics I linked to. An even better option may be to get rough settings using aperture priority then switch to manual and tweak a little.

How are you with histograms on the camera? You're exposures seem to be pretty decent actually, are you using histogram overlays to see how the exposure looks? If not, just spend a little time getting your head around them, they look scary but are really easy to use.

In terms of the apertures you've used so far, I reckon they could be a bit low for sharpness, I definitely reckon you could be going up a few f-stops and letting the exposure time or ISO increase to compensate.
 

sheriffwoody

Distinguished Member
I'd personally be more inclined to shoot in aperture priority on the sweet spot of the lens and let the camera decide how long to expose for. That's what I did with the pics I linked to. An even better option may be to get rough settings using aperture priority then switch to manual and tweak a little.

i normally use manual mode, but the reason i swapped is because i wanted the lens open for at least 10 seconds so i could get a nice light trail of the ISS - and this was the easiest way of doing it. if i had switched to aperture priority it ended up only allowing the lens to stay open for a very short time instead.

How are you with histograms on the camera? You're exposures seem to be pretty decent actually, are you using histogram overlays to see how the exposure looks? If not, just spend a little time getting your head around them, they look scary but are really easy to use.

In terms of the apertures you've used so far, I reckon they could be a bit low for sharpness, I definitely reckon you could be going up a few f-stops and letting the exposure time or ISO increase to compensate.

i have no idea what histograms are or what they do :laugh:
 

chum_2000_uk

Established Member
But if you keep your aperture not so open in aperture priority, say f8 and above and ensure the ISO is set to manual and keep it between 100 - 300 then your camera should have no choice but to choose longer exposures, there's no other way it could get enough light to correctly expose.

Histograms are really important to get your head around in digital photography IMO. They are the best way of ensuring your pictures are nicely exposed. Read this article and find the setting on your camera that turns them on:

Understanding Histograms

The reason I say learning how to use histograms is important is because relying on the camera to work out settings for you is not ideal. With difficult scenes such as night shots etc the camera will likely struggle to choose the correct settings for a good exposure. If you take a few quick snaps and check out the histograms you can instantly get an idea of if the scene is too dark or too light (under or over exposed) with your current settings and you can adjust aperture, shutter speed or ISO depending on what you want to achieve/ sacrifice.

I'd definitely suggest getting yourself some photo editing software and also shooting in RAW format too. Obviously photoshop is silly expensive, but there are lots of other good, much cheaper alternatives. Anything that can do basic sharpening, and alter contrast and exposure values would be a good start. I hear lightroom is very good.
 

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