Exmor vs DualISO

Note: This was a two particle article that I merged together so I may have missed some things and there may be sections where the writing doesn't flow properly.

I've already posted this on another website but thought people here might be intersted as well. I've noticed there's a feeling that MagicLantern's DualISO for the 5D3 is nothing more than a gimmick and that it's too flawed to actual be useful.I've been using it for over a year now and while there were some major tradeoffs to using it in the beginning, the MagicLantern guys (i.e. mostly A1ex) have made enormous steps towards making it a genuinely useful tool for high dynamic range shooting on Canon DSLRs.

When the A7R was first released I bought one because I wanted to see what it was like shooting on the same sensor as the D800E, but after a couple days I returned it because I just could not get over the terrible ergonomics and poor battery life of the camera. I did do some very rough comparisons between DualISO and the A7R at the time so I had some sense then of how they compared. Anway, fast forward to a couple weeks ago; like always happen someone was complaining that their 5D3 didn't give enough dynamic range, so I recommended DualISO and then a bunch of people started claiming that you lose half your resolution, get horrible aliasing and artifacts, it was completely unsuitable for printing, and still didn't get rid of the pattern noise or bring the DR anywhere close to an Exmor sensor camera. I wanted to create some kind of controlled experiment to compare a DualISO 5D3 with an Exmor sensor, as I hadn't seen anything like that online, so I bought an A7 and EF adapter to perform the test.

The first shot shows the two shots pictures with no post-processing exposure adjustments (Note: Please forgive the terrible picture, I was cleaning up my bike while I was doing this.) Exposure was set so that the sky was as exposed as possible without clipping and I turned off all the lights in my garage so that the interior was much darker. Focus is on the rectangular object in the lower left corner, which is a Risk box, and is ~5 stops underexposed. Both pictures were taken with a 70-200ii.

I then took both cameras hiking to get some more real world type pictures as well as to show one of the weaknesses that I know still exists with DualISO. For all of the following pictures I metered so that the highlights were just clipping (based on the A7 zebras) and then dialed it down 1/3rd a stop. ISO, aperture, and shutter speed are identical for each scene, although the light was changing quite a bit so not all shots are exposed identically but I'd say they're all within 1/3rd stop. For the first shot I was using a 40mm STM on the 5D3 and a 16-35 F4 IS on the A7 (made the weight distribution fairly even and meant I didn't have to constantly swap lenses), while on the last shot I used the 16-35 at 16mm for both cameras. Both shots were done at ISO 100 while the secondary ISO for the DualISO shots was 1600 for the first shot and 3200 for the last shot were I wanted to show a specific type of artifacting that can occur.

The first is a tree that had a nice dark shadow down the middle from a branch hanging just right with a bright blue sky in the background.

The last thing I want to show is that there is another type of artifacting that can occur in situations where you push the secondary ISO very high, for this example 3200, and you have thin lines (i.e. small branches or wires) running almost parallel to the sensor rows. On the left hand side of the frame in the shots below you can see a tree with some bare branches sticking out.

• Using a very high secondary ISO. This usually only happens over ISO 3200, and MagicLantern will warn you about using these settings.
  
• You have a very thin object. Thin as in less than ~2 pixel in width.
  
• That thin object is at an angle of less than ~15 degrees to the horizontal row of pixels.
  

Awesome write-up! Might have to dust off the 5D3 that's been sitting in my pelican case and try it out

wait, so does dual iso lose resolution or not?

With the new interpolation algorithms you don't lose much resolution at all if you keep the secondary ISO under 1600. If you look at the small text on the Risk box at near the beginning, that's the degree of resolution loss you can expect.

Another thanks for the comparison.

Re: resolution loss, the side by side comparison of the tree trunk at the bottom of post 2 is a pretty good example of difference in resolution

I have absolutely no idea how to use the dual iso thing in magic lantern. I tried and I couldn't get nothing but wierd crap all over the images. is that just playback or what.

I need to relook at this. I need linkage to help me out. any ideas?

When you look at the images on the camera LCD they'll look screwy. It's only after you've run them through CR2HDR that they look normal. This is part of the workflow problem that I mentioned. If you use Lightroom then I highly recommend the LR plugin that some of the MagicLantern community members put together, makes things much easier.

wow nice comparion. Kudos to magin lanten. And shame to Canon of falling behind in sensor But 5D3 isn't new, let's hope Canon get their act together and produce some good sensor again

Or maybe Sony will get their act together and make a camera that's more ergonomic and conserves battery life. Oh, and has a better viewfinder. And a superior lens system. Canon has done that already, so why is Sony so far behind?

I hope I don't have to put a flag here that says <tongue in cheek>.

eelnoraa wrote in post #17097070
wow nice comparion. Kudos to magin lanten. And shame to Canon of falling behind in sensor But 5D3 isn't new, let's hope Canon get their act together and produce some good sensor again

To be fair, the last 3 offerings from Canon has really shown improvement over past models, both in noise performance and noise quality. These differences shown in this thread, however illuminating they are between the differences of sensors and firmware, are not going to be realized by the vast majority of folks. Definitely landscape and architectural shooters are going to follow this, but the typical portrait, sports, wildlife, etc aren't going to be all that concerned by such a wide DR and how different cameras compare. For those more inferior cameras, you still have HDR capability with great software out there, so you can still do bracketed shots and quickly run them through the software to produce a wider DR result, so there is a workaround.

Speaking of that, raptor, have you tried the HDR mode of the 5D3 to see what result you get with that mode? It might be worth testing that next to dual ISO and vanilla 5D3 shots.

GregDunn wrote in post #17097718
Or maybe Sony will get their act together and make a camera that's more ergonomic and conserves battery life. Oh, and has a better viewfinder. And a superior lens system. Canon has done that already, so why is Sony so far behind?

I hope I don't have to put a flag here that says <tongue in cheek>.

it's a full time live view camera, it has it's pros and cons. The EVF is outright amazing, 90% of the time, I will prefer it. In really really low light, it's not fast enough to keep up with action and you may have timing problems due to sluggish reaction.

TeamSpeed wrote in post #17097741
Speaking of that, raptor, have you tried the HDR mode of the 5D3 to see what result you get with that mode? It might be worth testing that next to dual ISO and vanilla 5D3 shots.

HDR mode brackets exposure and shoots 3 shots. I use it a lot for outdoor photography, but since it's a continous shoot, you'd get registration issues in certain scenes with movement. The 5D records three RAWs and composites one jpeg image. I always trash the jpeg and just work with the RAWs: which because they're different exposures are effectively increasing the dynamic range. Dual ISO is improving shadows, but not recovering blown highlights.

TeamSpeed wrote in post #17097741
To be fair, the last 3 offerings from Canon has really shown improvement over past models, both in noise performance and noise quality. These differences shown in this thread, however illuminating they are between the differences of sensors and firmware, are not going to be realized by the vast majority of folks. Definitely landscape and architectural shooters are going to follow this, but the typical portrait, sports, wildlife, etc aren't going to be all that concerned by such a wide DR and how different cameras compare. For those more inferior cameras, you still have HDR capability with great software out there, so you can still do bracketed shots and quickly run them through the software to produce a wider DR result, so there is a workaround.
shots.

We are talking about two angles here. One, I really don't think the improvement in ISO will bring a vast improvemet in image quality from the eyes of general viewer. Most people won't even be able to tell looking at output on screen, internet or prints. Only for photographers (maybe) who like to analyse thing at 100%, the difference is appeaant. So in practice, I don't think there are much difference.

Now, as Canon user, supporter for so many years, I am not happy to see how slow Canon is advancing their product compare to other company. Canon was making, comparatively, better sensor back in the days (5D classis). This was also true for SLR video. Sensor performance, measureably, has been falling behind competitors. Video also seems to fall behind. I am hoping Canon will make a change.