Camera sensor dynamic range (DR) is refer to how much detail it can capture into a picture from very dark to very bright. A sensor with weak DR will either unable to capture details in dark shadow or blown out details in highlight. I am going to compare my A77 and A700 where DXO mark shows both DR score is 13.2 and 11.9 respectively. It is about 1.3 exposure value A77 better than A700.
The test is simple. I take a same shot with seven ISO speed, from 100 to 6400. Each shot is using aperture priority at F8 with exposure value (EV) set to -2. Later in Lightroom processing I will push the EV back to +3, means it become +1 EV overall. The objective is to examine how much details has been captured by each ISO and how good it can be restored. This is quite useful especially in certain condition our picture is underexpose and we can still recover it later in post processing. The question is how good it can be recovered without losing details.
Here is the original underexpose shot. It might be too dark.
Original Shots with EV -2
Let’s look at the EV +1. There are two objects behind the shadow. And the tiles surface is reflective. If higher EV been push will results overblown the highlight details.
Original Shots with EV +1
Let’s see how is JPEG comparison between A77 and A700 after the picture was post processed with EV +3.
Left to Right : A77 and A700
Top to Bottom : ISO 100,200,400,800,1600,3200,6400
SLT A77 vs SLR A700 (JPEG)
You will notice A77 pictures is slightly dimmer. Although both camera was set to same aperture and shutter speed. Let’s not worry about it, it could be the light lost in A77 due to the translucent mirror. My interest is to see how good A77 dynamic range compare with A77. A77 shows very good SR, up to ISO1600 it still maintain the highlight where A700 is losing the detail at reflective tiles. At ISO 6400, A700 produce a wash out picture where A77′s still usable in my sense. It is 1/8000, F8 at ISO 6400. I beg no one will shoot ISO 6400 in a sunny day. So I can conclude that A77′s ISO 6400 is about the same as A700′s ISO3200. It is about 1 stop light or DR level better.
Probably shooting in RAW can retain better DR value for post processing. Let’s see the same pictures which are convert from RAW to JPEG.
Left to Right : A77 and A700
Top to Bottom : ISO 100,200,400,800,1600,3200,6400
SLT A77 vs SLR A700 (JPEG
Looks like A77′s is underexposed while A700 is overexposed. There is how Lightroom process it when I set the EV to +3. Overall we still see A77 manage highlight better than A700 about 1 EV+. Let see whether there is more details captured by A77 under the shadow area.
Oh no! The A700 is a clear winner in details although it just have 12 megapixels. A77 shows very grainy noise and unnatural colours. I believe this is the the main problem lies in A77 image quality where the noise destroy the details. Noise reduction is no option to disable as well, only can set to weak. All A77 users are still eager waiting a good firmware update to resolve the issues.The version 1.04 is just for transition. Just like A700, it only produce real good image in its third firmware updates.
Conclusion, A77 has better dynamic range than A700. But in details it does not outperform A700. I will come up another details battle within this two camera soon.
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