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 Evening time exposures 
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Joined: Mon Oct 29, 2007 12:16 pm
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Post Evening time exposures
This evening, thinking about neutral density filters (which I don't have as yet) I thought I would do some time exposures of moving water using the diminishing light of the evening as a natural alternative to a neutral density filter.

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This is a fountain just off Mareeba's main street.

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I used aperture F8 for this photo,

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-and for this one, taken later when the sun had gone down. The fountain is not illuminated at night so I was fortunate that a car paused over the road, enabling me to get a shot with the water lit up a bit.

Mareeba bears no comparison to Whakatane for scope for evening and night-time time exposures. There's really nothing worth taking a photo of.

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Bunch of queen palms in the central reservation of the main street

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Looking north down the main street with the setting sun colouring the clouds. I think it is fair to say tourism was not uppermost in the minds of the town's founders.

Hoping to buy a neutral density filter during this week.


Tue Apr 01, 2008 10:13 am
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Joined: Mon Oct 29, 2007 2:06 pm
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Location: London/Lincoln UK
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Peter,

There are various post-camera ways of applying an ND filter rather than buying one. A decent circular polarising one I would have thought was more useful as I don't know of any means of applying that after taking the shot - cuts down on haze and reflections.

If you want the links to the tutorials let me know - but tell me what you use, i.e. photoshop or the GIMP.

HTH

Tim


Wed Apr 02, 2008 4:32 pm
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Thanks, I have had a circular polarising filter for some time. I used it on 25th November last year, on Green Island, before the onset of the current rainy season;

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- haven't used it since because during the summer it is nearly always cloudy.

How would application of a neutral-density filter effect in PhotoShop turn a sharp picture of moving water or a moving car's headlights into a motion blur, the effect I am interested in achieving, as in the photos displayed above?


Wed Apr 02, 2008 7:01 pm
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Location: London/Lincoln UK
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Peter,

Apologies, I assumed you were after a graduated effect rather than blur (increasing the exposure) - I was looking at the under-exposed foreground and thinking that if you lightened the image in PS (or whatever) and then darkened the sky using a gradient on a layer. Creating blur, well yes I suspect you can in PS but I'm not sure how realistic it would be.

I use a +2 filter very occasionally (for the waterfall/fountain effect when it's bright) and modify skies in the GIMP (equivalent to PS) to allow for darker foregrounds - with the latter it's possible to take two photos one over and one under-exposed (for the foreground etc) and combine them.

HTH

Tim

ps sorry for the long delay in replying, I haven't been on her that much recently.


Thu Apr 17, 2008 11:41 am
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Joined: Mon Apr 07, 2008 10:24 pm
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Location: Bristol, UK
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There are some excellent articles on how to combine multiple exposures at Digital Outback Photo. I have just trimmed down my collection of filters to:

ND filters: ND8 and ND64 (can stack these to get an amazing reduction)
Circular polarisers
UV filters - for use in mountainous areas - or shadowed areas lit by a bright blue sky - which can end up too blue.

I don't keep the UV filters on the lenses. There is much debate either way, and it comes down to personal preference.

By the way, there's an article somewhere on this forum with a picture of a blue flower and a comment by the author that it looks really bleached out and was much bluer in real life. Certainly it was true for film that strongly blue flowers, like bluebells, would bleach the film, because they reflect so strongly in the ultraviolet. They are known to be difficult to photograph for this reason. I am beginning to suspect that the same effect is at work in digital sensors, I took a couple of pics of a blue Streptocarpus a couple of days back and they were also disappointing. If so then a UV filter might help, as long as it really cuts out a lot of UV (they vary a lot in quality, and sometimes the most expensive makes are worse than the cheaper ones). There are good transmission % graphs here.

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Francis Bell, growing Proteas in Bristol.
51:29N 02:35W 63m ASL


Thu Apr 17, 2008 1:55 pm
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Francis,

ND64? Wow I didn't know they went that dark. I've used ND 4 and 8 but haven't seen anything beyond that. Do you have some shots that you can put up please?

Cheers

Tim


Thu Apr 17, 2008 2:14 pm
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Hi Tim,

They go a lot darker than that! B+W have a leaflet on their ND filters, the ones I have are 103 and 106, meaning that if stacked they give a reduction of about 9 stops, so i can do 3,6 or 9. This is generally enough for me - but they also make 110, 113 and 120 filters - the 120 gives 20 stops of reduction. Sadly some of the higher values seem to be no longer made by B+W - but you could possibly find one second-hand. Heliopan do them as well - see page 7 of their leaflet. The stronger ones are surprisingly difficult to find, PM me for a source of ND1000.

The higher values are typically used in astronomy - e.g. very long exposures of the night sky - for these you need a tripod plus a rotating platform (unless the aim is to make a star trails photo).

Some pics with the ND filter: Witches' Cauldron, Loch Arkaig, Scotland; in this one, the sun was obscured, and the dynamic range is just about bearable:

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The following picture has two problems - firstly droplets of water from the falls have settled on the lens making everything slightly out of focus, and secondly, the sun has come out, this was shot on slide film, and the dynamic range of the film just isn't great enough to capture the scene properly - the highlights are blown out, and the quartertones are all plugged.

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Actually there is another problem now - saving this as .jpg has created some nasty banding in the darker areas of the picture. I've got both side by side - web and Photoshop and the Photoshop image doesn't have the problem.

The dynamic range problem makes me wonder whether this type of photography would also benefit from HDR (high dynamic range) treatment.

Same waterfall, with a rainbow:

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Finally an old favourite of mine - Allt a'Chumhann near Kinlochleven, Scotland:

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The water is nice and clean, and the long exposure tends to make it invisible - the picture is mostly of the stream bed - except where there are some air bubbles in the flow, those areas show up white-ish. The blue tint to the water isn't Photoshopping, by the way - reflections of the sky over a long enough period of time make the water slightly blue where it is at the right angle. Some of the foliage which appears out of focus probably isn't - over a long enough period even on a fairly still day you will get some motion blur as leaves move around. The professional would pitch a tent and hang around till the wind died down, given that this is in Scotland, it could be a while :).

I don't have details of how long the exposures were, I'm afraid... I'm not that kind of photographer. I know some people keep detailed notes, when I have tried that, I just lose the notes, or I can't pair them up with the photos afterwards, or something. Actually, I was shooting on slide film until a couple of months ago, when I gave up the unequal struggle and went digital - so now the camera does keep track of stuff like this for me - exposure lengths and amazingly it even seems to know what the aperture was - even for 3rd party lenses, which amazed me the first time I saw it.

By the way, I'm viewing these on a Mac, and I know the PC uses a different gamma... I'm hoping they still look OK on a PC, I don't have one I can use to check (must get a bumper sticker saying "my other computer is also a Mac").

I hope this encourages anyone who is interested to try an ND filter (hint - if you have several lenses requiring different filter sizes, just buy the biggest size one and use a step-up ring for the smaller lenses. Just watch for vignetting if you're lucky enough to own a super-wide lens). It's great fun and if you're using digital, you don't have to worry about wasting loads of film if it goes wrong. :)

ND8's are great, not too expensive, and depending on the minimum aperture of your lens, at f/16 you are probably exposing for 1/15th or 1/30th, and if your camera will go to f/22 then you have 1/8th and if it will go to f/32 then you have 1/4. At 1/8th or 1/4sec you are starting to get some nice motion blur in water. On a slightly overcast day, you can get more - say 1/2sec to 1sec.

ND64s are more expensive, but on a nice sunny day you can make an exposure of perhaps a second, or two if overcast, and if you stack an ND8 with an ND64 you can get 9 stops, maybe up to 8 seconds. ND113 will give about 30 seconds of exposure. Another hint - if you've got an ND8 and you're depserate to get a longer exposure, you can stack it with a polariser for an additional 2-stop typical reduction. Yes, I have done this...

Will stop now as I am going on too long... I'll leave you with one more - not sure whether this really works as intended, I probably wanted an even longer exposure, but it's fun to experiment:

Image

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Francis Bell, growing Proteas in Bristol.
51:29N 02:35W 63m ASL


Thu Apr 17, 2008 8:59 pm
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Francis,

Thanks for all that, those look great. Until a year ago I was using slide too, but had bought myself a small compact digicam for travelling and found myself using that more. So I saved up and bought myself a Nikon D200 - I was using an F4 previously, Olympus OM1 before that. Interestingly I didn't own a single ND filter until I'd bought the D200, I used to wait until evening or get up early, then curse the contrast. Don't ask me why I didn't look into it more, probably time and laziness. :?

I'll have to reread that post at leisure, I don't have the time today.

Quote:
By the way, I'm viewing these on a Mac, and I know the PC uses a different gamma... I'm hoping they still look OK on a PC, I don't have one I can use to check (must get a bumper sticker saying "my other computer is also a Mac").


So am I since I'm at work, otherwise it's an ordinary pc running linux, although I also have an iMac at home I can use, so the photos look fine to me :P

Cheers and thanks for all that

Tim


Fri Apr 18, 2008 9:05 am
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I can ruefully confirm that you do need a particularly dark neutral density filter in order to get exposures of 1/4 second or more in mid-day conditions. I used an ND4 plus polarising filter for this shot, with aperture f8 and ISO 80 - and still it was only a 1/40 second exposure, so not the ethereal, floaty, misty effect I wanted. I wanted a darker filter, but Cairn's main photographic supplies specialist only seems to hold one item of anything at a time so if its gone, that's it until they have ordered one more up from Sydney, which takes two weeks. Grrr - part of the downside of living in Hick-land. I ought to disregard the so-called shops and order everything online I guess.

Image


Sun Apr 20, 2008 8:44 am
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Hi Peter,

Which one did you go for in the end ?

I guess the whole of the UK is hick-land then, I had to import my ND64 from Hong Kong (via ebay). They are barely available here and if they can be found then they tend to be crazy prices. Seems like it should not be too difficult to mix some black dye into the glass while they are making it, but what would I know ?

Yes, for something like ND filters, I would be tempted to buy online, as long as the filter is a reputable make then you can be pretty sure it's going to do what it says on the tin.

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Francis Bell, growing Proteas in Bristol.
51:29N 02:35W 63m ASL


Sun Apr 20, 2008 8:32 pm
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Mine's just a Cokin, although that set me back forty-five dollars. Cokin do an astronomical ND filter without a ND number, which might be comparable to your ND64, but it looks extremely dark - I wonder if it would be too dark.


Wed Apr 23, 2008 10:20 pm
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Yes, I think the astronomical ones are much higher than ND64, night sky exposure times can be several hours. Values of ND 10,000 or 100,000. I'd love to try the ND 10,000 though - on a nice bright day it could give exposures of perhaps 30 seconds to 2 minutes.

According to photo.net: "The (Cokin) ND100 (P155) is just over 6 stops and the NDX (P156) is 12 stops." The NDX sounds ideal for lightning photos. I have tried to do these in the past - I have an attic room with a good view of the Bristol skyline - but (a) the camera gets a good soaking, (b) I can't keep the shutter open long enough. Thunderstorms in Bristol don't seem to be the electrical-only type, they are generally accompanied by torrential rain, and I have to open the window because otherwise I can't see through it due the amount of water on it. Looks like there is a solution to (b), though.

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Francis Bell, growing Proteas in Bristol.
51:29N 02:35W 63m ASL


Thu Apr 24, 2008 1:15 pm
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There was an electrical storm tonight, so just for fun, I took a few pics. Some of these were on manual (bulb) exposure. I did try with the ND filter (NDx8), but I'm not sure whether it really helped, there is a lot of light pollution from sodium streetlights where I live.


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Strange that the lightning didn't go for the communications tower, although of course the strike could be much further away than that:
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Cropped from the following picture:
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Another crop:
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Despite appearances, my neighbour's chimney was not hit:
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Somehow the lightning always chooses to strike just where the camera isn't pointing, or just after the shutter has closed :-)

Also a lot of the lightning strikes were cloud-to-cloud, which seems to be the type of storm we get round here; cloud to ground strikes are comparatively rare.

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Francis Bell, growing Proteas in Bristol.
51:29N 02:35W 63m ASL


Fri May 09, 2008 10:24 pm
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