This article shares the results of an Olympus OM-D E-M1X ISO invariance test. My base image for this test was a tripod assisted photograph captured at ISO-6400. I then took successive images at ISO-3200, ISO-1600, ISO-800, ISO-400 and ISO-200 while shooting in Manual mode.
My skill set in post processing doing this level of recovery is very limited, so I apologize to readers in advance. I’m sure that someone more experienced with these types of adjustments would have done a far better job than I was able to do.
To set a benchmark for this E-M1X ISO invariance test, let’s have a look at all of the corresponding jpegs.
Now let’s have a look at these same images after the corresponding RAW files were adjusted in post. I used my standard post processing approach with DxO PhotoLab 2, CS6 and the Nik Collection.
Our last comparison in this article is to look at each out-of-camera jpeg and its corresponding RAW image after it was adjusted in post.
While I would seldom create a dark image purposely, other than for creative effect, it is reassuring to know that the RAW files from the Olympus OM-D E-M1X respond well in post.
I recently had a practical example of the benefit of this when capturing some family photographs. Due to lighting conditions some of my photographs were underexposed by 1-2 stops even when shooting at ISO-6400. Not expecting particularly good results, I lightened these family images in post. The quality of the finished images was a very pleasant surprise. They were absolutely useable and I would be comfortable printing reasonable sized enlargements from them.
Some people put a high emphasis on sensor size when choosing a camera and assume the worst about small sensor cameras like M4/3. Factors like IBIS performance, Handheld Hi Res mode (HHHR) and the degree of ISO invariance can impact how a camera like the Olympus OM-D E-M1X performs in lower light conditions.
Photographs were captured handheld using camera gear as noted in the EXIF data. Some images are out of camera jpegs while others were produced from RAW files using my standard process.
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12 thoughts on “E-M1X ISO Invariance Test”
Awesome, I was curious about my X’s. Cheers!
I performed a similar test on my EM1X up to 6400 ISO
I did the raw conversion using ACR yet it’s important to zero out all noise reduction.
Bottom line I found shooting at ISO 6400 with proper exposer looked a little better then shooting at ISO 200 and adding +5 EV in ACR . I also just looked the Blue channel as this is we’re you can see the noise pattern very clearly.
So based on my findings the EM1X is clearly doing some “ digital” gain when increasing ISO which is what most camera do today.
Though it’s always a good idea to do your own evaluation
Everything John mentioned above is 100% correct
Thanks for adding to the discussion… it is always great to have readers share their experiences!
It’s “astonishing”, isn’t it, Tom – – The first time one does this the results are remarkable and totally unexpected (at least, that was my experience).
Note to other readers, tho; results shown in Tom’s test (above) are possible only with cameras that exhibit tendency to be ISO-invariant (none are perfectly so) … and that’s not typical for cameras from one of the major manufacturers.
Some technical notes (from a self-confessed pedant!):
1) Your test images were not “under-exposed”:
Exposure involves 3 elements (none of which involves ISO), being aperture, shutter speed and quantity of light FROM the source.
Your exposure was the same for all images; f/2.8, 1/50 and a consistent light source (from what I can see in your images).
2) ISO (in digital cameras) is a process of magnifying the signal captured by the exposure – – and NOT (as is commonly, but wrongly, asserted) increasing the sensitivity of the sensor (which would be require defying rules of physics!).
3) What I find most intriguing is that we typically use ISO to achieve a faster shutter speed in low light conditions (to avoid camera shake associated with a slow SS) – but, by doing so we are actually *reducing” exposure (See above) !
This is also why we are not so bothered about low SS when using a tripod – – and we’re then able to keep a low/optimal ISO setting.
All fascinating stuff !!
Very interesting comment. However, don’t your 3 elements of exposure simply reduce to 2, since aperture and shutter speed determine the third, the quantity of light?
I never before considered that changing digital ISO is merely performing an in-camera effect that could also be done in post, correct? Having come from a film background, where changing ISO really meant changing the “sensor” (film characteristics), I always assumed that changing digital ISO somehow changed the characteristics of the sensor.
Yes, that is a very common misconception, Bill.
In film, each film type IS does have different degrees of sensitivity (as each type has different chemical composition) .. but a sensor’s physical makeup cannot be changed (as we don’t swap sensors in/out like we used to with film) .. instead, ISO now determines the amount of “amplification” applied to the digital signal taken off the sensor.
Re your question about 3 elements of exposure; the quantity of light coming FROM the subject is just another variable (like aperture and shutter speed) – it can be varied by, say, using a flash, or moving the subject into better light, etc.
Th term “exposure triangle” is wrongly used to include ISO .. if doing so, a better term would be “photography triangle” .. a minor difference.
Thanks for the additional input John!
I’m obviously not a technical photographer, and have admitted that here many times 🙂 … so my test was based on some other ones I had seen other folks do. My intent was to create a series of increasingly dark images, then lighten them in post to see what would happen. When I’ve done this same experiment with some other cameras in the past the results were quite poor. On a comparative basis I was quite pleased with the results from my E-M1X.
I went on the Photonstophotos.net website and compared the Olympus OM-D E-M1X Mark II and Mark III on the Photographic Dynamic Range Shadow Improvement versus ISO Setting chart.
I was surprised to see that there was a fair difference between these two cameras. While both curves are reasonably flat, the one for the E-M1 Mark III is flatter and lower. If I’m understanding the information you provided correctly, this would indicate that the E-M1 Mark III would be more ISO invariant than the E-M1 Mark II. As such it would respond better in post when an image is lightened which would provide more photographic options to an E-M1 Mark III owner.
Looking at the data there appears to be a 0.5 EV advantage for the E-M1 Mark III throughout the ISO range from ISO-400 through to ISO-12800 in terms of dynamic range shadow improvement. I imagine that for some folks who currently own an E-M1 Mark II this may be an important difference to consider when contemplating moving to the newer model.
Here are the chart values for both cameras:
ISO-400: Mark II 0.51 EV, Mark III 0.04 EV
ISO-800: Mark II 0.57 EV, Mark III O.O2 EV
ISO-1600: Mark II 0.65 EV, Mark III O.18 EV
ISO-3200: Mark II 0.83 EV, Mark III 0.42 EV
ISO-6400: Mark II 0.94 EV, Mark III 0.48 EV
ISO-12800: Mark II 0.98 EV, Mark III 0.48 EV
I went back to the article and adjusted some of the wording. I changed ‘underexpose’ to ‘create a dark image’. Hopefully this will be more technically correct.
I’m currently traveling (up in Cairns again) .. I’ll get back to you when I have a proper screen and keyboard to work with.
Great article ..
John – TKA
Thanks John… I appreciate your input and sharing.
Another great article on the E-M1X. You are truly a great resource on small sensor cameras. Thanks and please keep it up.
You’re welcome Jack! It’s always a pleasure to share my explorations with readers!