sony a7s and atomos shogun

the other week i finally got to test out the a7s/shogun combo with some friends while we worked on a short ad for local fashion company lulu*s. i also got to test out some fantastic led panels that jacob schwarz from mystery box lent our production (look for a separate review soon).

a7s_rig_1

my camera setup is pretty robust for a such a tiny mirrorless camera. full cage with lightweight 4×4 matte-box, rails, follow-focus and shogun up top with a massive sony battery. turns out i under- estimated the weight, and the tripod/head combo i got just isn’t quite beefy enough to handle the rig fluidly (it still worked, but needed a bit of post-stabilizing).

slog2 is impressive for a consumer device; you really can see all the latitude the camera is capturing. While that seems awesome initially, it comes with some notable downsides. mainly, all that latitude is stuck in an 8bit signal. even though the shogun captures 10bit, the sony only outputs 8 (something the gh4 has over it). being in such a crunchy space, it’s easy to imagine that all that information isn’t too malleable. lastly, the log shifts the curve in such a way that while it’s able to retain a lot of highlight and shadow detail, mid tones seem to be placed dangerously close to the shadow area.

shooting digitally i’m used to protecting the highlights, but oddly, i found that with the a7s it’s perhaps better to protect your mid-tones more than anything. to protect them, it would appear you’d want to expose them right near %65 ire. i’m used to 1ish stop over middle on key side, but you want the fill side to be around 1.5 stops over in this case to really keep noise out of the mids.

which brings me to another point. sony has a supremely wonderful denoising algorithm on its internal files, however when you’re pushing out of the hdmi at 4k, no such noise reduction takes place. even so, the camera can capture video at 25600 iso with a similar noise pattern to the epic dragon at maybe 2500 iso. it’s very impressive. but where that noise comes in is the problem. while i had heard that you should be over-exposing your mids a bit from the online community, i didn’t take it extremely seriously while we were shooting. so in some cases where i’d exposed skin at maybe 18% thinking i could bump it in post… its pretty noisy. turns out bumping the iso to keep your mid tones exposed results in much more manageable noise than an underexposed image.a7s_rig_2

after a bit of time checking out the footage in post, it seems that iso 3200 is quite clean (when exposed properly) even though no noise reduction takes place on the hdmi out, and as long as your mids are at least 1-1.5 stops over exposed, the image is remarkable in how crisp and how malleable it is in speedgrade. this is going to be key for my future shoots. We also tested some night shots in a local mall, lit only by the led lights strung throughout the establishment. the shogun made it appear we were getting a great image, and while it’s certainly an impressive image considering we shot it at 25600 iso, i should have opened up a little more on my lens (i was sitting at a 5.6 so I wouldn’t have to worry about focus too much) to over-expose the mids a bit more.

ultimately here is the formula that works for me: use the iso to bring your image to the correct levels, all the way up to 25600. expose your mids 1-1.5 stops over middle grey.

the noise is much cleaner on an properly exposed high-iso image than underexposed footage with even a dramatically lower iso. (i’ve since shot a scene entirely at 12800 iso properly exposed and the noise is quite subtle when just a grade is applied, more on that on a future post).

to sum it up: the a7s and shogun creates an impressive budget 4k package. the lack of raw information is frustrating in post, but the flat slog2 retains enough information, that in the hands of a decent colorist, can create a wonderful image. the video appears to be quite sharp (given the lenses used) and skin tones are malleable enough to create a pleasing tone (they may start a little yellow but are easy to pull back into healthy territory). lack of high-speed can be frustrating coming from a r3d background, but when matched up with other cameras in it’s price range ($3.5k-$5k), the lack of speed seems about right. ultimately, paired with the aforementioned opinions and its full frame/low light capabilities, make it a solid contender in its price bracket.

if you’re worried about the much-discussed battery issues with the a7s and shogun, i think what you’d need for a full day (12 hours) shoot is a minimum of six a7s batteries (and 2 chargers), and 3 sony npf970 batteries with a rapid dual-charger for the shogun.

media-wise there isn’t a significant difference between proros hq, 422, and lt when it comes to the a7s. one 120gb ssd gives you abut 44 minutes of record time at lt, so you don’t need to go crazy (2 120gb drives has been plenty for me so far).

i’ll hold off on a more in-depth review of the shogun for now. suffice to say the screen is amazing (but super reflective, as you can see above), and while light-weight feels a bit delicate. it eats batteries, but it also gives live wave-forms, false color, peaking, and will punch in 2:1 and 1:1. seems reliable so far, but it’s also missing a ton of features and only recently received playback (we had none for this shoot). ultimately, paired with the a7s , it can produce some fantastic 4k images.

finally, here are some graded shots (examples of proper exposure, and under-exposure), check out the description for each for more information:

color test 11 color test 12

 color test 15color test 16

color test 14 color test 13

4k video available here.

 

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