Sony a7sii and the End of the Reciprocity Law
Sony's newest kid on the block and the Eradication of the Law of Reciprocity.
This is the camera that will supposidly blow all other camera gear out of the water. And coming directly from the mouths of Sony fans this is suppose to be the DLSR KILLER. This is Neo. The One. (Cue "Killing in the Name of" by Rage Against The Machine.)
The first Sony A7s was expensive. Body only was expensive. It is still expensive at $2500. But the results were worth it if you read the reviews. And it is tipped that the A7sii is to hit the $3000 mark. DAYUMMM!
What the A7s brought to the table was its high performance ability to shoot in low light. Compared to some of the more outrageously priced professional cameras such as the Nikon D4s or Canon 1DsmarkIV it performs as good or arguably better than these DSLRs.
All this from SONY!!?? Mirrorless. DAYUMMM, DAYUMMM.
With the A7s you also had 5 axis stabilisation which means you could take pictures jumping on a trampoline and the pictures would be tac sharp, so even at slower shutter speeds the results will still remain the same... flawless.
But this is its new brother.
The A7sii as before boasts a maximum sensitivity setting is ISO 409,600!! It also brags intself on 4K recording, better noise control and improved autofocusing.
Some previews I have read state that this camera would still function in almost pitch black conditions. DAYUMMM, DAYUMMM, DAYUMMM!!
As I was reading the previews and rumours surrounding the A7sii and I constantly read the anticipation on how it will work its magic around low light surroundings when my mind suddenly snapped to a word. Something long forgotten but like a crack of a whip it came to me.
I remember this word back when I was using film. It is a Law described in layman's terms as this:-
When light levels drop, the normal reciprocal relationship between shutter speed and aperture breaks down.
In regular daylight conditions, the relationship between the amount of light and the exposure time is constant. So if the light levels halve, you need to double the exposure time to get the same result. However, this rule – The Reciprocity Law – fails when using film in very low light levels.
Once the exposure time becomes longer than a few seconds, the film no longer reacts in the same way – responding with colour shifts and progressive underexposure. This characteristic is known as reciprocity law failure. The precise amount of failure varies between different films, but as a general rule of thumb you need an extra half-stop for exposures from 1 to 10 seconds.
Up to 30 seconds, add 1 stop, and beyond that, another 2 stops for longer exposures. So, for example, if your camera indicates it needs an exposure of 15 seconds, the exposure needed will actually be 30 seconds to ward off reciprocity law failure.
So what has this Law and the Sony have to do with one another? Well even though we are in the digital age and reciprocity primarily focused on film and how it reacts to lighting conditions there is still a "grain" of truth that can be taken over to the digital realm.
Digital sensors tend to be very linear in their response to light, in both time and intensity. Long exposures suffer from noise and become unbearable. This is surely an instance of Reciprocity.
So I sit here with that word in my head, the Sony a7sii filling my eyes and I wonder with all the hype and supposed truly amazing low light performance will we finally see now, the end, of the Reciprocity Law?