View Full Version : Long shutter speeds

26th July 2011, 04:09 PM
My new LCW 9-stop ND filer arrived today, so I thought I'd make up a quick cheat sheet for working out exposures if I'm using bulb (my 520 only meters up to 60s). While doing so a question cropped up:

The shutter speeds we know aren't always what they should be. For instance, half of 1/125 isn't 1/60. But while the missing 200ths of second aren't too much in that respect, when you get into long exposures, the difference is a bit more. As said, my 520 meters up to 60s, but shouldn't that really be 62s?

And if so, the next stop should be 132s, not 120s, which is quite a difference. It obviously gets larger from there on in.

I'm not planning to, necessarily, make a lot of exposures that long, I'm just wondering what the correct technique is in that regard?



26th July 2011, 04:22 PM
And if so, the next stop should be 132s, not 120s, which is quite a difference.

It should be 124s (62 x 2) which isn't much different from 120s in practice (or even more accurately cameras should go up to 64s giving us 128s (not much different from 125s) as the next step) - I doubt you'd be able to tell any difference. If you want total accuracy then just use 1,2,4,8,16,32,64,128,256 etc.

But when you do start to use the filter I'd be really interested in your opinion on it as I've considered getting one myself.

27th July 2011, 11:41 AM
Oops, yes, my maths are a little shaky there. I was mainly thinking that as exposures get longer the disparity gets larger...

I'm hoping to get out and give it a proper go over the next few nights – I'll report back when I've got some shots. I tried a couple of quick test shots yesterday, and first impressions are that it is indeed fairly neutral (my worry was that it wouldn't be), if maybe a little cool. Looking forward to getting out and shooting some stuff.

I'll get my cheat sheet sorted out too :)

27th July 2011, 11:47 PM
I tried making up a cheat sheet, but it got a bit messy when trying to take into account different exposures, apertures and ISO’s. In the end I made up one of these.

http://e-group.uk.net/gallery/data/660/Exposure_Calculator_1.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/37283)

http://e-group.uk.net/gallery/data/660/Exposure_Calculator_2.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/37284)

http://e-group.uk.net/gallery/data/660/Exposure_Calculator_3.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/37285)

It is made up from a couple of pieces of plastic pipe. The upper ring fits onto the lower ring, is free to rotate and the two rings are kept from separating with a piece of string.

The lower ring has a numbered tape, starting at 15, going down to 0 and then back up to 15. Each represent 1 stop of exposure, let you read off the exposure for your required number of stops.

The upper rings tape has exposures, apertures and ISO’s. These are:

Exposures, starting from 1/4000 down to 30 minutes, in 1 stop increments.

Apertures, starting from F22 down to F2, in 1 stop increments.

ISO’s, starting from 3200 down to 100, in 1 stop increments.

I mostly use it for night photography. Having taken test shots to find the best exposure at ISO 3200 and the lenses widest aperture, I then use the calculator to find the exposure based on ISO 100 and my chosen aperture.

Saves me lots of frustration, head scratching and wrongly exposed photos.

http://e-group.uk.net/gallery/data/660/Forth_Rail_Bridge.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19686)

http://e-group.uk.net/gallery/data/660/20110504_239_oly.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/34020)

http://e-group.uk.net/gallery/data/660/20100423_26.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/23046)

28th July 2011, 08:14 AM
That sounds like a very interesting idea - perhaps you could sell the idea...!

28th July 2011, 09:23 AM
That sounds like a very interesting idea - perhaps you could sell the idea...!

I presumed there would be a smartphone “app” which could do the calculating. My plastic pipe and string “app” lacks the touch screen and 24 month contract, but it is certainly Orange.

If people are interested I could make more ….

28th July 2011, 11:27 AM
That's a pretty cool thing. You'd pay about £20 for that camera shop... I was thinking of something along those lines, but maybe with two rotating (flat) discs. Not sure yet. The germ of the idea is in my head, but not the execution.

Funnily enough, given your (excellent) pictures, I was down at South Queensferry last night trying out the filter. Just going to have a sort through the photos and post some impressions.


28th July 2011, 12:13 PM
Having gotten out and grabbed a few shots, first impressions are:

a) The filter tends to make the white balance rather cool, so best shoot Raw, or do a custom WB.
b) The camera doesn't seem to accurately meter with the filter in place, so it may be best to work out the exposure and use manual (I usually use Aperture Priority).
c) The filter is pretty thin, so it shouldn't vignette – certainly didn't on the 11-22mm. It does make it a little fiddly to put on though, best not to try if wearing mittens!

Here are some photos from last night – quite late on, admittedly, which maybe didn't help with the WB. All are out of camera jpegs, just resized. All are set to F8, ISO 100 and sunny WB.

A shot without the filter (1/10s):


Same shot with the filter (6s):


Same again, + 1 stop Exposure compensation (20s):


Same again, + 2 stops Exposure compensation (40s):


This is looking the other way, toward the road bridge. This is F5 at ISO 200, + 2 stops. WB at cloudy (25s).


I think I need a bit more practice to get it working right, and will need to shoot Raw (I did Jpeg & Raw for these), but it hsould work okay. Looks like +2 is the bare minimum comp needed for it though...


28th July 2011, 01:06 PM
The other option for longer exposures at that time of evening is to use a smaller aperture.

I found using Manual mode and RAW shooting gives me control rather than having the camera decide on how things should be done.

If you use ‘Bulb’ mode the longest exposure with your E520 is 8 minutes – use a remote control and you will not have to touch the camera

If you want a bit higher tech you could use a remote control timer

I keep watching the skies around sunset time, hoping for a bit of inspiration, but just seem to keep seeing the same band of low cloud over Fife and no nicely coloured clouds.

Remember to keep looking around, often the best part of sunset is the ever changing colours of the clouds behind you.

Good luck with your calculator. I thought about the circular plate route but could not find a simplistic way of laying out all the exposures, apertures, ISO’s and stops, at a legible size whilst keeping the plates small enough to fit into a pocket.

29th July 2011, 11:36 AM
Yeah, I just don't like the loss of sharpness that accompanies stopping down to F22. Whether the filter makes this better or worse, I don't yet know...

I've actually got a wee third-party wireless remote. Works fine enough and I'm pretty sure it can do bulb exposures – though I'll have to check. That said, the item on the second link would save faffing around with stopwatches...

Having looked at those pictures I posted, the correct exposure (1/10 + 9 stops) should be about 40 seconds (I've not worked out the 1/3 stop increments yet), so the the +2 stops picture should be about 'correct'. Still looks a little dark to my eyes, but practice will get me there.

I know what you mean about the light – it's only ever good when you're nowhere near anywhere photogenic or busy doing something else. Though it's worse in winter when I have to watch the lovely sunsets out of the office window then walk home in the dark.

Finding an interesting location is another thing again – Queensferry seems to have become my default go-to location when I go out.

I think my calculator may end up being as simple as a list of shutter speeds with the shutter speed + 9 stops next to it. Experimentation may be the key.

Out of interest, how long were the exposures in the pictures you posted?

29th July 2011, 06:54 PM
Here is the link to a chart you can download - http://stephendickeyphotography.com/northern_ireland_landscape_photography/neutral-density-filter-chart-for-landscape-photographers/

The exposure times for the photos are as follows:

1 - Forth Rail Bridge – 118 seconds

2 - Midnight at Glen Tanar House Trout Loch – 360 seconds - the moon was only 0.5% illuminated and the orange lights in the sky were from forest fires on the Balmoral estate

3 - Not All There at Bealach na Ba – 148 seconds

If you go west through South Queensferry, past Port Edgar on the coast road, just past the entrance to Hopetoun House, there is a handy headland for views like this

http://e-group.uk.net/gallery/data/660/Forth_Road_and_Rail_Bridges.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/19688)

The light trail in the sky was from a plane landing at Edinburgh Airport. This was a 118 second exposure.

If you use a remote timer you can set a delay before the exposure starts, giving you time to go off and do things like this.

http://e-group.uk.net/gallery/data/660/20100423_20.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/23042)

The remote timer has coloured LED’s so you can see when it is in delay modes and when the exposure starts, and stops.

1st August 2011, 04:10 PM
Interesting. I'm going to have to go out and do some experimenting. I'm taking a trip to the States at the end of the month (Washington/Oregon/Yellowstone/San Francisco) so hopefully I'll find some good subjects and nice light there. Going to post the one decent shot I got from this session into Foto Fair, if you're interested.