The long and the short of dark glass

I have not blogged for a while, to tell you the truth, I kind of took a scunner to it, that and a general lack of free time has somewhat cramped my style lately. However, things are a changin’ and I should start having a lot more free time very soon.

Last week, I took the plunge and bought an expensive piece of dark glass, mainly because I could see the potential for long exposures in my aircraft and landscape photography.

The quest for dark glass stems from last year’s Christmas present which was a Cokin Z-Pro filter kit. The kit came with a mounting frame but not the adapter ring, that was extra and three ND Grad (Neutral Density Gradated) filters at ND2, ND4 and ND8, which equates to a one, two and three stop light reduction. The kit comes in a large but very functional filter wallet.
Shortly afterwards I added a Cokin ND8 Grad filter to the set.

The only negative comment that I can level against the Cokin kit is how the individual filters storage wallets are marked as they each bear the Cokin catalogue numbers, i.e. Z121L, Z121M, Z121S and Z154 for the ND8 Grad. It would have been easier from my point of view to have just plain ND2, ND4 and ND8 on the wallets and so making them easier to find.
Fortunately, the filters themselves are marked with the ND number, so all is not totally lost.

Why use the filters?
You can add a graduated filter in post-production and I will grant you the points if you said that you could do it better in Lightroom but I wanted to apply the Grads in-camera rather than in post. The long exposure part can only be done in camera anyway.

I have noticed in my aircraft photography that even though I stand with my back to the sun, it would seem that most of the light seems to come in from the sky above the subject, either over exposing the sky with a correctly exposed aircraft or vice versa. So the ND Grad reduces the light from the sky and gives a more even exposure throughout the image. I also like a dark sky as it helps to concentrate the viewers eye ont he aircraft.

The traditional way is to mount the camera on a tripod, then insert the ND grad and adjust it up and down until you get the cut off where you want it and then take the picture. Well, I’m awkward and generally hand-hold my camera, getting more or less the same result.
This was one of my first photos with the filter, I think this was the ND4.

G-BGIG PA-38 Tomahawk

1/350 @ f/8, ISO 200

So with that part up and running, I turned my attention to the real purpose that I wanted to put the filters to and that was the streaked sky effect, that you can only get from the dark glass.
The big name in the dark glass business is Lee Filters, their ten stop or “Big Stopper” is as expensive as its name suggests and one has to add on the price of the mounting kit and adapter ring which will leave you with little change out of £250. Lee makes pro quality gear so it may be worth the money but not for someone starting out with long exposures.
It is also at times as rare as rocking-horse poo, being hard to come by at times.

Looking about on the internet I found a ND1000 (10 stop) dark glass filter made by Haida for £77, expensive but more affordable than the £100 for the Lee Big Stopper.
The filter duly arrived in the post and in true fashion the weather turned dreich and I was not able to get out and play with the new filter for a week or so.
I did manage to get out one morning to try the filter but no sooner had I got the camera mounted on the tripod and the mount fixed onto the lens than I turned around and the sky behind me was as black as the Earl of Hell’s waistcoat, a portent to a heavy rain shower. The nice clouds that was over Bishop Hill then started to firm up and all that I got were three test shots; one normal, one with the ND1000 and one with the ND1000 and ND8 filters.
The clouds were slightly blurred but not what I wanted, as the exposure time was not long enough. The naked exposure was something like 1/180th adding the ten stops brings it down to six seconds and the ND1000 & ND8 was 30 seconds. The overall effect was to smooth out the clouds but the streaky cloud effect that I desired was not there because they had firmed up by this point.
The other down side was a marked magenta colour cast on the ND1000 & ND8 combination. As you can see I managed to null most of it. Unfortunately I was unable to run a colour profile on the combo due to the imminent rain shower so I had to null the colour cast out by eye.
On reflection, I should have included more of the surface of the loch in the picture to show that being evened out. Live and learn I suppose.

ND1000 6 seconds @ f/8, ISO 100

ND1000 6 seconds @ f/8, ISO 100

ND1000 & ND8 30 seconds @ f/8 ISO 100

ND1000 & ND8 30 seconds @ f/8 ISO 100

1-180th @ f-8, 100 ISO

1-180th @ f-8, 100 ISO

I managed another shoot with the ND1000 at Scone on an aircraft this time and the results were interesting, bearing in mind that this was a test shot and nothing serious.
This was another six second exposure, with a well blurred prop and a nice effect from the pilots head.
This test did help me with another concept photo that I have been working on, so I now know that that part will work but that will have to wait until I can find a nice day and a very co-operative pilot.

6 seconds @ f/8 ISO 100

6 seconds @ f/8 ISO 100

My latest and most successful picture to date came the other day when I had the opportunity to photograph a helicopter out on the grass at Scone. The naked exposure was 1/90 at f/11, 50 ISO, which brought the 10 stop exposure down to 15 seconds at f/9.5, ISO 50… I was a wee bit careless with a half stop but the image worked and while the clouds are not as streaked as I wanted them to be, the guy ropes and tapes on the blades are blurred enough for me. It just goes to show how much you never see.

15 seconds @ f/9.5 ISO 50

15 seconds @ f/9.5 ISO 50

Lee supply a chart with their big stopper where you can read off the naked shutter speed and dial the 10 stops directly into the camera. The Haida ND1000 does not come with such a chart, however my camera is set to half stops instead of the footery third stop intervals, so it’s no big deal to count 20 clicks to dial in the ten stops.
There are charts available on the internet that give you these settings but come on, counting one, two, three… nineteen, twenty isn’t that hard!

The one other item is that the Cokin filters are all made of a resin type plastic, while the Haida filter is made of glass, so knowing me, the chances of me dropping it are reasonably high so I’ll be doing a lot of cursing when that happens.
The Haida filter does come in a nice padded filter holder so it’s well protected in transit.

That brings us up to date, the weather has typically turned pure dreich and my filter fun will have to wait until another day but until then…

Mair tae come


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  1. #1 by Dan Traun on February 23, 2015 - 12:37 pm

    I just recently bought the same Cokin kit. I concur re: catalog numbering.

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