D800 and E-M5, can you tell the difference?

Started Mar 25, 2013 | Discussions thread
acahaya
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Re: Update: flickr set with plus 1, 2, 3 EV images
In reply to Anders W, Mar 27, 2013

Anders W wrote:

acahaya wrote:

I finally managed to finish my own small test of raising EV and/or using fill light on those images. If interested, you can find the results (including exif data) in a set here on flickr: http://flic.kr/s/aHsjEuLLM2

The motivation for me was to find out how much more lattitude regarding noise and shadow detail a D800 will give over the E-M5 when shot at base ISO. I rarely use higher ISOs for images i plan to pp but unfortunately most comparisons only look at higher ISOs and ignore heavy base iso raw tweaking.

The results are roughly what i expected but it was nice to see that my initial expectations were confirmed. The E-M5 will do nicely for what i need and the D800 is simply amazing.

Sabine

You exposed the E-M5 at 1/200 and f/8 versus 1/125 and f/6.3 for the D800. So, assuming that the light level in the studio remained unchanged, you gave the E-M5 1.3 EV less light on the sensor.

Yes. I already explained why in the OP and in several answers. Everything was set up for the D800 and i just grabbed the E-M5, made sure that the skin was about right and also shot some pictures.

But there is absolutely no reason to do that. If you look at the DxOMark "measured ISOs", which are effectively a measure of how much light it takes to reach the clipping point of the sensor at a certain camera ISO, you find that the E-M5 base ISO is 107 versus 74 for the D800. That means that the D800 can take only marginally more light (about half an EV) than the E-M5, not one full EV less light as the camera ISOs (200 versus 100) might have you believe. So at least part of the reason why the D800 shot gives you more latitude in PP is that the E-M5 shot was "underexposed" by nearly one stop relative to the D800.

This is all very well in theory but in this case i had limited time on the set, the model was moving, i.e. changed distance from the strobe and in this case you simply set up the cam for the intended aperture, make a test shot, maybe adjust the strobe or cam  and then its pose shoot pose shoot ... i.e. there simply isn't time to check exposure between each shot. There also is no time to change the light and shoot another set of test shots if you want to take pictures with a different cam, you just grab it, make one test shot, check the blinkies and shoot before you change the cam again. The model may have been closer to the light in my test shot withbthe E-M5 and then have moved further away, i honestly don't know anymore.

If your model is not moving at all, you are shooting from a tripod and have all the time in the world, you will for sure  go for perfect exposure. If you plan to compare cameras, you'll also plan the scene ahead and make sure both cams are set for perfect exposure. This was not the case here.

If the model is movingand you are moving for different angles and the time is limited, you simply go for an exposure that will be more or less OK and fix it in the RAW converter later on if necessary. This is one of the resons why lattitude at base ISO is important to me.

Consider additionally the DoF requirements. You could have shot the E-M5 at two stops wider than the D800 for roughly the same DoF (at the same subject magnification). Suppose, for example, that f/8 and 1/125 is what you need for proper DoF and control of subject motion with the D800. You could then use f/4 and 1/125 on the E-M5 to achieve exactly the same thing.

Regarding F4, sure. If i plan to shoot with the E-M5 i will adjust the strobe to shoot with something between F4 and F6.3 at 1/200s. I prefer 1/200s with moving models anyway. But for most of my images there is only one DOF requirement and that is as much DOF as possible because composing is much easier with in focus areas, i.e. it is hard to realistically blend an oof area with a bg.

Again, this is different if you plan to make comparison shots where DOF might be a factor or if you go for shallow DOF.

Now suppose you can't use f/4 and 1/125 on the E-M5 without dimming your studio lights. Well you can. Just use a magenta filter of the kind I describe here

http://forums.dpreview.com/forums/post/51133125

and you are effectively down from ISO 107 to ISO 25 with the E-M5 so that it can stomach the exposure you are in a position to give it. That treatment would reduce the difference in PP latitude between the E-M5 and the D800 even further.

I will try using a magenta filter next time. Promised

I am not saying the difference would disappear altogether. But if you make sure to maximize the exposure the E-M5 can take, by taking stock of what its base ISO actually is in terms of DxO "measured ISO" rather than nominal camera ISO and make use of the filter, the difference will shrink quite significantly.

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