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Month: August 2015

Sony A7R II Long Exposure Tests.

Brendan

A7R II is the buzz word at the moment in the photography circles, with most reviews holding it in extremely high regard. So naturally I had to test the sensor for long exposure noise.

The results can be seen on the long exposure sensor testing page, and here are my thoughts:

There is no doubt, the A7RII is very impressive, considering the size of the sensor it’s delivering much better results than the D810 or the 5Ds(r). It’s performance is generally much better than the older model (A7R) and it’s results are almost identical to the Canon 6D, keeping in mind the 6D is only 20MP one can’t but help be impressed.

One of the reasons I started my long exposure testing was because no one was doing long exposures at high ISO. All the low light tests performed I could find were at best a second, and in most cases much shorter than a second, in some cases as fast as the body could shoot (1/8000th). But sensor behaviour for longer exposures is not consistent, and in some cases it’s not very linear. What is good for sport is not good for astrophotography.

The A7RII’s sensor behaviour is a very clear example of why this test is important. There is no doubt for general low light work or sport this camera is going to be a killer, but what about longer exposures? At 30 seconds the A7RII is holding it’s own, but starting to loose the edge it had at 1 second, and by 5 minutes significant noise has been introduced into the shot, and it looses it edge to many other models. There is no doubt that Long exposure NR enabled would fix some of this, but not all.

So my conclusion is, it’s going to be an awesome camera killing other models for shorter long exposures (1-10 secs), it is going to match the high end models in the 10-30sec range having the benefit of more MP, but for longer exposures other models start to win out including the 5Ds(r), I’ll be very interested to see how this one goes in the field and I think there is the possibility of further testing to understand the ISO to time relationship, for example higher ISO’s for shorter periods could yield better results than lower ISO for longer periods.

Please keep in mind my tests do not take into consideration other factors such as dynamic range (DR) or how linear the ISO relationship is (ISO-less or not). I am purely interested in the noise (floor) and what you will have to deal with in post.

Playing with the light. ND Filters.

Brendan

Most good modern DSLR’s have a good amount of Dynamic Range (DR), DR is the measurement from the brightest to the darkest a sensor can capture in one image, beyond this range highlights will be blown and dark shadows will yield no detail. It is normally measured in Exposue Values (EV). A Good sensor will be at least 12, and maybe as high as 16.

But what do you do if the image you are trying to capture has more DR than my sensor can capture? Well there are a number of ways to deal with this, these are the most common:

  • Take multiple exposures to combine into one image, either as a composite merge or a high dynamic range shot (HDR), later models can do HDR in camera.
  • Add additional light to the scene.
  • Use filtering effects to modify the light being exposed.

BPD_1948HDR and adding light are fairly common, but using filters is not very common for night sky photography and Aurora’s. The reason it is not popular is that adding filters reduces the amount of light entering the camera, resulting in either having to use higher ISO settings or longer exposures.

However given the right circumstances using a filter can have great results. I like to use them for shooting Aurora’s provided the Aurora is very bright and it has minimal movement. If the Aurora is bright I don’t need to increase my ISO, and minimal movement like beams in the Aurora will mean I can increase the exposure time a little without blurring any details.

I have found that using a 0.9 (3 stop filter) helps significantly with exposure compensation, balancing out the light Aurora in the sky to darker foregrounds. Not only does it help with the balance and bringing out blacks, but it effectively gives your sensor a 3 stop advantage.

A sensor that can shoot 14 stops of DR is suddenly equivalent to 17.

Suddenly I’m no longer dealing with those horrible black dark areas where the noise hides.

I can’t say it enough, foreground!

Brendan

The other night I was out shooting an Aurora with a friend of mine, and we were discussing what can make or break a shot. What is it about some scenes that make a photograph popular?

To be honest the Aurora Australis is not all that hard to shoot, you join a Facebook page, find out when the actions happening and the weather is clear, then go out and setup your camera pointing south with the settings everyone is willing to freely give you. The result? Well we have all seen them, the countless shots from decks and backyards.

BPD_1844So, what am I waffling on about? Imagination, creativity, beauty and effort. Yes, effort. A good shot does not happen when you drive into a carpark and proceed to setup your camera next to your car. A good shot takes research, framing and most importantly good subject matter. A good Aurora is not good enough by itself (yes there are exceptions to the rule), a good shot draws you in on many layers, first it may be the Aurora, but then your eyes start to wander as you look at the other subject matter and composition.

It’s very important to make sure your shot is level, and you use the proven framing techniques, and that the rest of the shot enhances the main subject matter, in the case of an Aurora maybe it’s reflections on water, interesting foreground subject matter or some lovely rolling hills. Also, try to avoid to much subject matter drawing your else away from the central theme, or bad subject matter.

Anyone can shoot a car, anyone can even shoot a nice expensive and exotic car, but it’s never going to look nice unless you place the car in surroundings that enhance the featBPD_1843ures of the car, and of course, shot in a way that enhances the cars features.

In the days before digital cameras you knew you only had one, maybe two rolls of film for a shoot, consequently much more time was spent on planning and setting up shots. Today there seems to be this idea that quantity is going to make up for quality. Sometimes I may only shoot 6 pictures, and at most I generally never go over 50.

The best shots are always the ones that have been researched, pondered upon, then with the subject matter framed correctly.

Could you go out and ONLY take 24 different shots?