Beginner Trying to Master Long Exposure

Chris J

Chris J

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Hi all,

I was out yesterday with cam, thought I'd give long exposure a go.

I like this kind of shot.

This is how I had cam setup: F11 / S 30" M & Manual Focus - remote shutter release setup and working. ND4 Filter attached.

Light was not bad, bit overcast but plenty of light.

Anyway, after 30 secs once shutter had closed and cam had processed the image it was just a white screen.... Tried 2 or 3 times on 30secs. Did I need to leave shutter open longer ?


Thanks
 
Chris J said:
Hi all,

I was out yesterday with cam, thought I'd give long exposure a go.

I like this kind of shot.

This is how I had cam setup: F11 / S 30" M & Manual Focus - remote shutter release setup and working. ND4 Filter attached.

Light was not bad, bit overcast but plenty of light.

Anyway, after 30 secs once shutter had closed and cam had processed the image it was just a white screen.... Tried 2 or 3 times on 30secs. Did I need to leave shutter open longer ?


Thanks
Click to expand...

Chris, it sounds like you over exposed the image if it was a completely white screen.
30 secs exposure I would generally expect with a 10 stop ND filter, even then I would likely use f16 or thereabouts.
 
I would think you had the exposer set to long, without being there it's not possible to be certain what the correct time should of been. Try 1sec then 2sec then 4 sec then 8 etc and see what turns out then you can fine tune it around the best result.
 
if it was a "white screen" then there was WAAY too much light getting in - hardly surprising over a 30 second exposure, considering you'd only got f11 plus a ND4 - effectively, another 2 stops - or f22...

(a quick run through with the "sunny 16" lightmeter in my head, reckons that 1/100th second at f8 and 100 ISO would have been about "normal" exposure - so you'd be looking at 3 stops slower shutter speed than that as being "acceptable" as a starting point... maybe 1/15th or 1/8th of a second... so, 30 seconds is definitely over the top... as in a good 8 stops too much... )
 
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Thanks guys, I did try f22 but only at 30secs. Ill see if I can get an ND10. In the meantime try longer shutter ?

BULB mode, f22 ?
 
Chris J said:
In the meantime try longer shutter ?
Click to expand...

Noooooo! As I said above, you're shot would have been properly exposed (assuming 100iso set on the camera) at around 1/8th of a second with f11 and the 2 stop filter.

Even with f22, you'd only gain 2 more stops of slowing down, so 1/2" exposure.
 
Chris J said:
Thanks guys, I did try f22 but only at 30secs. Ill see if I can get an ND10. In the meantime try longer shutter ?

BULB mode, f22 ?
Click to expand...

In good light as you mentioned it was that day, in order to get such a long exposure you would need a 10 stop filter Chris.
However, with your ND4, lens stopped down to f16-22, lowest ISO, you should still be able to achieve a longish exposure, not 30 secs though.

In the meantime, try a shorter exposure. As Andy mentioned above, 1s, 2s, 4s, etc. Double your exposure as you go until you achieve your desired result.
 
This chart should help you understand better the relationship between pre filter attached shutter speed and filter attached shutter speed.

neutraldensityfilterchartbystephendickey.jpg
 
Chris J said:
I see you can get variable ones on the net from ND2 to ND400.

Are these any good ?

http://www.ebay.co.uk/itm/58mm-Slim...708715?hash=item3f5e295ceb:g:cNEAAOSwmmxW4Fdk
Click to expand...

Nope, they're bloody terrible... they're actually 2 crossed polarising filters - the more you turn the light blocking up, the more it moves one polariser towards 90° in relation to the other polariser - which blocks more light. Problem is, the "darker" they get, the more uneven the effect can become - especially when used on a wide-ish angle lens (as lots of slow-speed landscape type shots tend to be).

A friend bought one, and brought it to me saying "I think this is broken, can you look at it for me" - was another of these sum £10 wonders, badly build, poor materials, and the polarising lenses were loose in the frames, so as supplied it barely worked above about 3 stops. As they'd ordered theirs from china, there was no point in bothering sending it back, so I tried to "fix it" - I rotated the "moving" polariser in the frame until it gave something like 8 stops worth of "block" - so it did work after a fashion - however, the blocking was uneven across the image - banding of light then dark then light then dark again (strange, as I'd expected it to be more like a polarising filter fitted to a Wide Angle Lens, giving more effect at one side of the frame than the other....) - in short - Bloody Awful.

Some of the more expensive variable ND's aren't too bad, but expecting something for £6.38 from fleabay to be a universal panacea is going to be a fools errand...
 
TheBigYin said:
Nope, they're bloody terrible... they're actually 2 crossed polarising filters - the more you turn the light blocking up, the more it moves one polariser towards 90° in relation to the other polariser - which blocks more light. Problem is, the "darker" they get, the more uneven the effect can become - especially when used on a wide-ish angle lens (as lots of slow-speed landscape type shots tend to be).

A friend bought one, and brought it to me saying "I think this is broken, can you look at it for me" - was another of these sum £10 wonders, badly build, poor materials, and the polarising lenses were loose in the frames, so as supplied it barely worked above about 3 stops. As they'd ordered theirs from china, there was no point in bothering sending it back, so I tried to "fix it" - I rotated the "moving" polariser in the frame until it gave something like 8 stops worth of "block" - so it did work after a fashion - however, the blocking was uneven across the image - banding of light then dark then light then dark again (strange, as I'd expected it to be more like a polarising filter fitted to a Wide Angle Lens, giving more effect at one side of the frame than the other....) - in short - Bloody Awful.

Some of the more expensive variable ND's aren't too bad, but expecting something for £6.38 from fleabay to be a universal panacea is going to be a fools errand...
Click to expand...

I'd figured as much, It was just an example!!

Can anyone recommend anything ?
 
if you're intent on going "cheap"...

https://www.talkphotography.co.uk/threads/10-stop-filter-for-£2-really-d.151141/page-2



ETA: Just gave my mate a call... the one who bought the variable ND... after that, he bought a cheap-ish 10 Stop ND from fleabay that wasn't actually all that bad - reasonably accurate at around 10-11ish stops (it CAN get a bit "near enough" at that kind of attenuation, so its not a big deal) and not too bad a colour cast... he's just emailed me the link to the ebay seller...

think this was the one... this is a 77mm diameter, obviously, you'd need to get one that suits the lens you're using...

http://www.ebay.co.uk/itm/77mm-ND10...amera-LF510-/161928291606?hash=item25b3ada516
 
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TheBigYin said:
if you're intent on going "cheap"...

https://www.talkphotography.co.uk/threads/10-stop-filter-for-£2-really-d.151141/page-2



ETA: Just gave my mate a call... the one who bought the variable ND... after that, he bought a cheap-ish 10 Stop ND from fleabay that wasn't actually all that bad - reasonably accurate at around 10-11ish stops (it CAN get a bit "near enough" at that kind of attenuation, so its not a big deal) and not too bad a colour cast... he's just emailed me the link to the ebay seller...

think this was the one... this is a 77mm diameter, obviously, you'd need to get one that suits the lens you're using...

http://www.ebay.co.uk/itm/77mm-ND10...amera-LF510-/161928291606?hash=item25b3ada516
Click to expand...
Nah im not intent on going cheap per se, More interested in knowing what I need. I may check out the recommended Ebay links though

Thanks all.
 
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ND filters are marked in different ways. NDx4 is only two stops, or may be labelled 0.6 in optical density. Ten stops is NDx1064 (rounded to x1000) or 3.0. It reduces the exposure 1000-fold and the filters appears almost completely black to look through. All extreme ND filters like this must be completely sealed to the front of the lens (screw-in is better for this) and also cover the viewfinder to prevent light leaks getting in there.

NDx2 = 1 stop = 0.3
NDx4 = 2 stops = 0.6
NDx8 = 3 stops = 0.9
NDx16 = 4 stops = 1.2
and so on...
 
Thanks everyone for your replies, Ill head to ebay and grab a cheapish one and do some testing see how I get on and invest in something more pricey!!

:)

Thanks all.
 
@Chris J Just to play around and get the feel for it you could try using a piece of welding glass for only a few quid on ebay. When you have got the hang of it then look into getting a proper 10 stop filter which could cost you a lot of money for a good one with no colour cast.
 
Big Andy said:
@Chris J Just to play around and get the feel for it you could try using a piece of welding glass for only a few quid on ebay. When you have got the hang of it then look into getting a proper 10 stop filter which could cost you a lot of money for a good one with no colour cast.
Click to expand...

There is no need to start off with welding glass these days with decent 10 stop filters available for a tenner (see links above).
Don't get me wrong, I really like using welding glass, in fact used mine yesterday, but it is a lot more difficult to learn with and get good results, especially in colour.
I suppose the other way of looking at it is, that if you can master using welding glass, using a 10 stop after is a breeze ;)
 
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If you have a smart phone there are apps to tell you the exposure conversion i.e. no filter to exposure filtered if it helps
 
BlackCloud said:
If you have a smart phone there are apps to tell you the exposure conversion i.e. no filter to exposure filtered if it helps
Click to expand...

Another method, if your shutter speeds are set at 1/3rd stop increments (the factory default) is to count the clicks, ie three stops is 9 clicks, ten stops is 30 clicks etc. That only works up to 30 seconds max though.

Also, you need to check the density of your actual filter. These extremely dense filters are rarely exactly as marked, and can vary batch to batch. Just shoot the same scene with and without the filter, adjust until both exposures are the same and note the difference in stops. That should then hold pretty good for all situations.
 
I bought a fairly cheap 10 Stop ND filter from Amazon and been really happy with it. There is a bit of a colour cast but nothing that can't be easily removed.

I don't bother with any calculators for working out exposure. Start with ISO 100, f16 and 30 seconds. Then look at what you get and adjust from there.

Kenny
 
Kenny Girvan said:
I bought a fairly cheap 10 Stop ND filter from Amazon and been really happy with it. There is a bit of a colour cast but nothing that can't be easily removed.

I don't bother with any calculators for working out exposure. Start with ISO 100, f16 and 30 seconds. Then look at what you get and adjust from there.

Kenny
Click to expand...

Even the best and most expensive ND filters have a colour cast, even if it's only slight, eg B+W is warm, Lee is slightly blue. And it really doesn't matter. What matters is the colour accuracy after adjustment in post processing (or in-camera with a custom WB). With B+W and Lee etc, they are able to deliver a better final result, throughout the visible spectrum, by having slight errors corrected in PP as opposed to doing it with different dye recipes in manufacture.
 
Thanks all for the advice and recommendations... when I get a spare 5 minutes Ill give another go!
 
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