Monday, 30 March 2009

Eye Sensitivity

CatchlightIt has been said that the human eye has a maximum aperture of f3.5, a shutter speed of about 1/30s and a maximum sensitivity equivalent to ISO800. It got me thinking that if I wanted a photograph to look like my unadjusted night vision I could use these settings and get an appropriate exposure for a night scene. I tried this out and ISO800 was a little on the dark side I found that ISO1600 was much closer to the scene I observed with my naked eye. Not that I'm bragging about my night vision or anything.

It seems to me that this could be a useful rule of thumb for manually setting an exposure where the camera's light meter would be fooled by the darkness into overexposing everything. Get in that ballpark and then dial up or down to suit your taste. More easy to remember than f3.5 1/30s ISO1600 would be f8 2s at ISO100.

Of course the thing that would mess things up is the eye's enormous dynamic range, because when you look at the street lights your eye will change its aperture and sensitivity to suit. The camera's sensor may struggle to capture everything, so you may well need to expose for the highlights, but the rule of thumb may be good for getting close.

Here is an exercise for you, calibrate your night vision starting at our rule of thumb exposure f3.5 1/30s ISO800 take a shot, then adjust the ISO, aperture or shutter and chimp until you see in the viewfinder what you see with your own eyes. What is your baseline for night vision? Are your eyes more or less sensitive? Drop me a comment and let me know what you get

Saturday, 21 March 2009

Mounting a speedlight to a softbox

SoftboxA while ago I bought a main's powered flash and softbox from ebay. The flash is one of those things that I'm unlikely to use very often and will stay at home, but I have been thinking of ways of leveraging some more value out of the softbox by mounting it to a stand and mounting a speedlight to it.

Mounted I had a couple of strobists around to my house last weekend and they figured out how to mount it to the stand. The speedring for the softbox is rather large. It uses four screws which can be tightened to attach the mains powered flash. If you turn one of these around and screw it in tight, you can put it into the top of a standard umbrella mount.

ClampedWith that problem solved all thats needed is to mount the flash. This can be achieved by using a clamp with a ball head, which you can clamp to the speedring and then attach the flash to the ball head using and adaptor. You could use the foot that the flash came with. In this case I'm using a sonia all purpose adaptor and the clamp I got from Maplins

The softbox is still slow to put up and bulky to pack compared to an umbrella but when I get a bag with wheels, is going to be a very useful addition to my kit.

Saturday, 14 March 2009

Petition to reverse the latest photographic restrictions

ChattingOn the 16th of February, the Government passed a law (in the Counter Terrorism Act) making it illegal to take a photograph of a police office, military personnel or member of the intelligence services - or a photograph which "may be of use for terrorism". The legislation is fairly vague which means that its going to be difficult to prevent the police from abusing it, just as they already abuse section 43 and 44 of the anti-terrorism act.

This act doesn't just affect the rights of photographers. By enabling police to threaten people with arrest for taking photos they will be less accountable in those rare situations when they cross the line. You can find out more from this article in the Guardian and when you are done reading, why don't you head over to Number 10 and sign the petition

Saturday, 7 March 2009

Do Something Funny

Do Something FunnyThe London Photography Meetup Group organised a charity event in aid of comic relief at Portobello Road market. A ridiculous number of photographers turned up, showered people with leaflets and took portraits galore. I had a 2:30 slot booked and set up a couple of lightstands with white shoot-through umbrellas which I gaffer taped to our market stall and the adjoining stall.

The umbrellas created a cross light at about 45 degrees to the sitters. The rear umbrella was about three times further from the subjects than the front umbrella and contributed a nice soft highlight on the subjects right hand side. The ambient was underexposed by about one stop.

Shooting groups with this setup worked reasonably well. You had to take care not to let people fall into each other's shadow which was difficult in the cramped conditions.

It was a fun hour for me, a little chaotic perhaps, but a great way to raise money for charity. You could construct a little photo booth and create studio quality portraits in just about any location.

Wednesday, 4 March 2009

Farewell Lord Dearing

Lord DearingLast September I was photographing the LAFTAS awards for the CILT The national centre for languages.

The show was a tough gig, the lighting was very low and there were two lecterns on either side of a big screen and only one place that I could safely put a flash. I had a choice of two backgrounds, black or vomit green. I had hoped to be able to use the screen, and had balanced the ambient and flash, aiming the flash to miss the screen, but the colour of the screen was so bilious that it just wasn't possible.

While I was reading through the program waiting for things to kick off an old boy came over and started chatting to me, he asked me a few questions about my camera, told me about photographing his grandchildren and how a photographer friend of his told him that all the technical stuff doesn't matter, you can learn that, but its how you deal with people that matters. I had no idea he was Lord Dearing until he climbed up to the podium later in the evening.

Ron Dearing was a pleasure to photograph, wonderfully expressive, full of life and laughter. Sadly he passed away on the 19th of February aged 78. Its a great shame as he seemed to have a lot left in him to give.