Sony Alpha 7R II: Real-world ISO invariance study: Digital Photography Review

Article

The recently announced Sony Alpha 7R II packs a lot of groundbreaking features, and one of its highlights is the new full-frame 42.4MP BSI-CMOS sensor. Sony sensors tend to show very high Raw dynamic range due to low noise characteristics, but we wanted to take a closer look at exactly how little noise the camera itself contributes to images. So we performed our typical 'ISO-invariance' analysis on the camera, but with a real-world scene. Have a look at the results for yourself.

Preface

Recently, we've been testing the 'ISO-invariance' of cameras in a controlled manner, as a means of comparing Raw dynamic range across cameras. Before we move on to the Sony a7R II results, we thought we'd do a quick refresher here.

A camera with a very low noise floor is able to capture a large amount of dynamic range, since it will add very little noise to the detail captured in the shadow regions of the image. This means you can push those shadow regions and make them visible, allowing you to expose your scene for the highlights, and 'rescue' shadows later. Cameras with lower dynamic range provide less of an ability to do so, meaning that pushed files look worse than files exposed 'properly' at the time of capture.

All of this has an interesting implication: a camera with a very low noise floor (high dynamic range) minimizes the need to amplify the sensor's signal in order to keep it above that noise floor (which is what ISO amplification conventionally does). This provides an alternate way of working in situations that would traditionally demand higher ISO settings. In a nutshell, it means that once you've determined your optimal shutter speed and aperture settings, you can forego the higher ISO setting - which really only brightens your file in-camera - and adjust your exposure later.

Why would you do this? To protect highlights. In fact, I used this methodology to achieve the shot taken on the Nikon D810, a highly ISO-invariant camera, below:

We've published this image a few times on DPRreview, because it's a good real-world example of what can be achieved when using a camera with very wide dynamic range.

This shot was exposed for the highlights by keeping ISO near base. I shot in M mode which allowed me to dial in a wide-open aperture and the shutter speed necessary to freeze the action (1/640s). In order to ensure I didn't blow any of the sky, I kept my ISO down at 140. Pushing shadows/midtones 4 EV in post, while holding back the highlights, I was able to tonemap the scene to my desired vision, without tones becoming too noisy. All thanks to the Raw dynamic range of the Nikon D810, and its Sony sensor.

ISO-invariance

In our ISO-invariance test, we do something that may seem counter-intuitive: we use the same aperture and shutter speed at different ISO settings, and then equalize brightness of all resulting Raw files in post-processing. Recall that your ISO setting in your camera is simply an in-camera 'brightening' slider of sorts, so what we're essentially looking at is: what is the difference between brightening in-camera by increasing ISO (and using hardware, mostly analog amplification) vs. brightening after-the-fact in your Raw converter (digital correction)?

Below, you'll see a bunch of shots at different ISOs. Note that all shots X EV below ISO 6400 were adjusted +X EV in ACR. For example, the ISO 100 shot was pushed by 6 EV, ISO 200 by 5EV, and so on. An 'ISO-invariant' camera shows little cost to boosting a low ISO file in post-processing, while an 'ISO-variant' camera (which has lower dynamic range) shows significant cost to performing this exposure adjustment in post-processing as opposed to in-camera via setting your ISO to a higher setting.

Image comparison

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As you can see above: there's a very modest visual difference* in noise between shooting at ISO 6400, compared with using the camera's base ISO (100) and digitally pushing later. Why does this matter? Well, for a start, it shows that the sensor is contributing very low levels of downstream read noise, which is impressive in itself. But it also opens up the option to use the shutter speed and aperture value you'd usually use for ISO 6400, while staying at ISO 200 and using a much lower level of amplification and, then, selectively brightening your image later. Using a lower level of amplification means that highlight detail is less likely to get over-amplified and blown-out. And you can see this in the signage: lower ISO settings retain more detail in the bright sign, whereas all detail is blown in the ISO 6400 shot.

Now, we're not saying there's no cost to keeping your ISO low and brightening in post.** We're saying that the cost of a 6 EV push of an ISO 100 shot (vs ISO 6400) is only a mere half a stop or thereabouts in shadows, with almost no visible cost in midtones.*** Meanwhile, you give yourself no less than 6 EV highlight headroom by decreasing your ISO to 100.

Raw Compression

Speaking of that sign, take a look at the unpleasant artifacts around it. With the a7R II, Sony continues the tradition of lossy Raw files, with no option for lossless 14-bit Raw. This isn't going to affect all your photographs, but it can rear its unsightly head at high contrast boundaries of pushed files. The area around the sign in the ISO 100 + 6EV and ISO 200 + 5EV shots have artifacts not present in the higher ISO shots. These posterization artifacts are due to Sony's lossy compression, which you can read more about in Iliah Borg's excellent study here.

We think this Raw compression is particularly a shame, especially when you consider how ISO-invariant this camera is otherwise. As you saw above, the pushed ISO 200 shot has very little additional noise compared to the ISO 6400 shot. This is because of the high dynamic range, and ISO-invariance, of the camera, which means that realistically you can save much of your image brightening for post-processing as opposed to increasing your ISO setting in-camera. However, you'll be limited in your ability to do so because of Raw compression, essentially meaning the camera isn't as ISO-invariant as it could be.

In summary...

As we've come to expect from Sony sensors, the a7R II's high dynamic range means the camera is fairly ISO-invariant. This means you can often save image brightening for after-the-fact, affording yourself (potentially) stops of highlight headroom by keeping analog amplification low in-camera. You can do this by shooting in Manual, holding your shutter speed and aperture at whatever is needed for the higher ISO your low-light situation demands, but then simply dialing down your ISO setting.

Sadly, Raw compression means you'll be limited in your ability to do so, due to the potential for posterization artifacts around high contrast edges.

One thing to note: on many cameras, working in the manner we're suggesting may be awkward, because it can mean trying to operate with a very dark preview (because the camera thinks you're under-exposing when you dial down that ISO setting). But on Sony's newer cameras, you can employ the ultra-flat S-Log2 gamma curve from the Picture Profile menu. This super-flat tone curve ends up representing relatively dark captured tones as mid-tones, which allows you to see the wider dynamic range the camera and our eyes are capable of when shooting in the manner we're suggesting.

Footnotes

* Remember to turn off 'Shading Compensation' so you don't get weird artifacts like this near the edges, even in Raw (scroll back up to the widget after clicking this link).

** In terms of noise levels, there actually is some cost to pushing in post-processing as opposed to performing analog amplification in-camera (leaving aside discussion of Raw compression). In this case, this can be both a good and bad thing. Even with the best cameras with the lowest noise floors (e.g. Nikon D810), we see a bit of a noise cost to performing amplification in post vs. in-camera, and this is due to some residual downstream read noise, likely including some quantization noise due to insufficient ADC bit-depth for the large full-well capacities of such cameras. Part of the noise cost with the a7R II, though, is likely due to an additional benefit of the higher ISO settings on this camera: a higher conversion gain. Bill Claff's data on the a7R II vs the a7R indicate that at ISO 640 and above, a higher analog gain is applied fairly upstream in the signal pathway, which can help overcome the finite downstream read noise that, while incredibly low in Sony sensors, still is non-zero. In this case, then, 'ISO-variance' is actually a good thing, with the camera only truly ISO invariant from ISO 640 and above. Confused? It's a bit much to elaborate upon here, so let's discuss in the comments below!

*** For reference, here's what 1 EV differences in noise performance look like between different ISO settings on a D750, or what a 1 and 1/3 EV difference in noise looks like between formats (D750 vs D7100 in the link provided). The noise performance cost we see in shadows in our a7R II ISO 6400 vs. ISO 100 + 6EV shots appears to be less, to our eyes, than any of the differences you see here, hence our 'merely half a stop or thereabouts' comment.

Comments

Total comments: 372

Blimey, to think I just point the thing at something nice and press thebshutter....

1 upvote

I do hope that we'll soon see BSI sensors for aps-c :-) available to Pentax and Nikon.

0 upvotes

I have still not seen why no one mentions the split ADC approach used by Sony on A7RII and other sensors.

I guess it is about video ease/speed vs a full 14/16 bit ADC, but does it somehow effect the ability to do full 14bit loss-less Raw files ??

Anyone know?

0 upvotes

The dual conversion gain happens inside the Active Pixel Sensor (APS) so I doubt this has any effect of the bit depth of any downstream electronics.

0 upvotes

Nothing really special for $3200 body only cam.
The D7000 does just as good, even at ISO-5000.
Just learn how to use your tool.
http://s244.photobucket.com/user/rvrsbnd/media/de8c4ba4.jpg.html

Comment edited 48 seconds after posting

0 upvotes

That's saved everyone a few quid then!

2 upvotes

Great test! Move cursor to the Street-pointer on the word "Was...". Under letter "W" there is a light source. Its going to loose details already on ISO 200. So you can't restore it, if you have no data. So, if one wants to get max from this particular camera, just follow the test's advice - keep it as low as possible, use PP. Yes, this fantastic machine for people with very advanced PP technique, otherwise use something else, 800-810 is great enough. I do!

1 upvote

Look the dual light-pole at the corner, at ISO 100 you can see the air holes on the metal ring around top of the glass, but after 100-400 (depending which one you look) the details are gone. So bright light areas gets severely clipped, but otherwise details are kept very well.

But nothing so special after all.

0 upvotes

Fri13, with some reservations, agree. What I like - 5 ways of OS, wide abilities to use any optics. But DR is still less then Nikon's one. Will see.

0 upvotes

Rishi, you are too aggressive in your replies, and not the first time either. Its obvious what's going on with Sony

4 upvotes

Perhaps Rishi is understandably tired of having to defend what is a completely reasonable review? Or perhaps he's tired of newbies and laypeople telling them how to run DPR and what they "should" be doing.
I know I am.

9 upvotes

This is definitely a great article. Keep them coming!

1 upvote

How to do a +6EV push in ACR?

1 upvote

I know of two methods.

1st and easy: make an off-image gradient, boosting exposure by +4EV. Then the exposure slider effectively works as -1EV to +9EV.

2nd and more complicated: Export image to PS (as 16 Bit Tiff) and convert to 32 Bit. Save and back to LR. Now the exposure slider magically supports a -10EV to +10EV range.

1 upvote

@falconeyes: No way! Giving this a try right now (your option #2). If that works, you'll have saved us a lot of headache :)

Does LR preserve its aggressive highlight rolloff with this method? One issue with taking images into Photoshop is that exposure adjustments are applied without roll-offs, so highlights clip easily.

Personally, I think ACR needs to turn up the volume on most of its sliders to cope with the incredible dynamic range of certain recent offerings.

2 upvotes

We can run some experiments. My #2 assumes that the RAW is preprocessed to have no clipped channels. Also, I assume that the 32 Bit file is reimported into LR. No exposure is altered within PS!! The LR rolloff behaviour should remain the same.

But I confess it is a while ago I tried this the last time ...

> ACR needs to turn up the volume on most of its sliders

IIRC, LR increased the exposure variance from 4 to 5 EV.

1 upvote

@falconeyes I had no idea that the slider will magically have 10EV+/- when converted to 32-bit! But I did notice a strange change. When I "Edit in photoshop cc" and I convert it to 32bit mode then then save it which naturally adds 32-bit TIFF in LR and for some reason, the image looks more like the default JPG (more contrast/saturation) and is overall brighter than the default on NEF. In fact, the TIFF does not match the TIFF in PS CC at all. But I was able to use the EV slider and get far more details in shadows than I could in default NEF. Definitely something is going on. I am just stunned how much potential there is. I am using Nikon D5500

@Rishi it would be nice if you could report your findings with falconeye's methods.

0 upvotes

A 32 Bit Tiff file has arbitrary default brightness (set when being converted). The initial brightness when imported back into LR is to be ignored.

BTW, beside 32 Bit Tif, 32 Bit linear DNG does the same trick. It can be created by DNG converter (IIRC) or by LR 6's new HDR merge feature. Maybe, HDR merge would work with two identical RAWs too ...

1 upvote

That's a very useful tip. I need to play with this sometime.

0 upvotes

I now played with the possibilities a bit and this is the result ...

First, let's recall the methods:
#1 Off-Image Gradient+4EV + Exposure
#2 Export to PS, save as 32 Bit
#3 Duplicate RAW, merge both into one HDR (LR-Shortcut ^H)

In #2 and #3, exposure sliders support a -10 to +10EV range.

Findings:
Methods #1 and #3 yield identical results. #1 is easy and remains my preferred method. Rishi, what do you use at DPR?

#2 works and yields similiar results. However, unlike the 16 Bit tiff file, the 32 bit tiff file has much more default contrast. This makes it a bad choice for one to one comparisons.

The reason why #2 doesn't work as expected is a bug in LR: PS saves 32 Bit files with gamma=1 (whatever be the profile) but LR treats it as if having gamma. To work around, one would have to use a linear color space supported by LR and convert to that in PS before converting to 32 Bit.

Happy re-exposing :)

0 upvotes

Thanks for the additional info. :)

0 upvotes

Here is an idea, why doesn't DPR just do a review of the camera and be done with it?

Instead we have extensive discussions of the technology of this particular camera and "reviews" of other cameras that fall far short content-wise of what Phil Askey used to put out years ago.

1 upvote

So when we forego really, really technically detailed analyses for a product for a quick review (E-M10 II), b/c it's more an iterative update than a whole bunch of new technology that needs to be tested/addressed, you complain the reviews fall short.

OTOH, when we go really in-depth, & publish one piece at a time b/c each piece is so in-depth that it requires its own treatment, and so that we can update you on findings while the camera is still relevant, and then you also complain.

If you could carefully spell out exactly what it is you'd like us to do, we'll try and address your feedback, b/c as it is, I'm honestly confused.

6 upvotes

Rishi
OMG...Weekend. Finally got to dig into the S Log 2 that you explained some in the RX100m4 review. Also a new feature in the A7rii.
This picture profile thing is making a whole new level of adjustments available to photographers... Real world potential is HUGE... We need a whole separate article or series of articles just about the adjustment features in picture profile. I am testing today. But it will take weeks just to understand the many areas of potential and learn how to apply. Don't listen to Dave. We need more technical articles that help us learn to use the cool new features coming our way.

1 upvote

So Rishi please keep up the good work.

Comment edited 1 minute after posting

2 upvotes

Tech/detailed reviews simply make some ppl's HEAD HURT !! Trying to do something the brain is not capable of maybe ?

Keep on with as much tech detail you can, but add a very simplistic 'Executive Brief' for those whose heads hurt !! ;)

Ouch, me head hurts !! ;)

1 upvote

Yes, I like the idea of an Executive Summary (i.e., "tl;dr" version) - but perhaps that's what the already included Conclusions is about. Maybe feature that Conclusions section up front for those that don't want to skip directly to the end using the pulldown menu?

0 upvotes

There are dozens of 'Quick' / 'Executive Summary' / 'Feeling' type reviews. I ignore them all. I want highly technical analysis when looking at buying a camera. DPreview is one of the few sites that provide that.

1 upvote

Regarding phase detect sensors embedded on the image sensor: I assume these phase detect "pixels" take real estate away from image pixels? Does Sony interpolate image data for these "holes" in the image array?

3 upvotes

Yes, it gets interpolated just like on the Olympus E-M1 does it.

But it is just a single R, G or B pixel, that gets then calculated from surroundings without data loss.

Only pixel peepers are worried about it, even when there are 399 sub-pixels lost because of that, from over 42 million of them.

http://www.imaging-resource.com/PRODS/olympus-e-m1/ZTECH_PDAF_PIXELS.gif

Comment edited 43 seconds after posting

0 upvotes

The
DSC09021.arw
is the ISO 100 Image. I just ran it through originalraw. All i can say about the original JPG result is, that the image is massively underexposed. Maybe its underexposed by 7 stops. Boosting that image by 6 to 7 Stops and complaining afterwards doesnt make any sense.

Who on earth takes pictures at EV-7 GENERALLY ??
I never do.
As a photographer its your job to expose the Sensor of you digicam CORRECTLY to get the maximum SNR.

I think Sony did very well here, providing
40 megabytes for each ARW file (lossy)
instead of
70 megabytes for each ARW file (lossless).

Lossless RAW with 70 megabytes may be only useful for a few boosting brightness by EV+7.

But the majority of the photographers can save a lot of Space, and most of them, never take pictures at EV-7.

Lossless ARW with 70 megabytes filesize may be a welcoming option, but it should be optional, but i would never use it.

Comment edited 2 times, last edit 1 minute after posting

1 upvote

I would suggest Sony giving ppl a choice of lossy or lossless raws.

As to why Sony can not do a lossless but compressed raw still baffles me, as don't other makes offer this ??

4 upvotes

@ www_zeeshan_de,

unfortunately, you don't have a valid point.
First, you seem to miss what isoless is all about. Read up about it, it will benefit you in your photography. Rishi does the right tests here.

Second, Nikon D800 14 Bit lossless NEFs are the same size as Sony lossy ones. Sony destroys image information for no reason. Lossless compression is as old as ZIP and older...

And BTW, there are much better ways to do a lossy compression. No measurable loss in image quality and much smaller output files. No vendor does it ATM, but the methods exist. Maybe, I should write about that ...

Comment edited 2 minutes after posting

0 upvotes

@falconeyes re:lossy compression alternative algorithms - no measurable loss or no "perceivable" loss? Got links?

Sony probably thought their scheme was imperceptible too until DPR formulated a pathological - though not unreasonable - example.

0 upvotes

@steve_hoge the algorithm is unpublished own work. Like some lossy compressors, it makes use of photon shot noise statistics. However unlike any existing approach, I rescale the statistiscs to hold true at all spatial frequencies. Something the other lossy compressors fail at miserably. Also, I add any noise I removed at compression when decompressing. Therefore, two separate reads of the raw file yield two different uncompressed images. However, against a third, stored w/o compression, no method could know which one was stored which way.

0 upvotes

@www_zeeshan_de, of course, you don't need to shoot at EV-7 (I don't think there is any camera with that much range in EV). The point of the article is showing how it makes little difference between shooting with a given high ISO in camera and pushing the ISO in RAW editor from an image taken at ISO 100 if you're using an ISO invariant sensor. When you shoot at low ISO despite being underexposed by a few stops and develop in an editor, you could preserve highlights better.

With that in mind, using the ISO invariant sensor, it's a good idea to expose for the highlights and push the shadows in RAW editor and not worry about the chroma noise that would have popped up if for an ISO variant sensor.

The technology behind the ISO invariant sensor is exactly why I switched from Canon to Nikon. I do see huge differences in shadows when pushed between Canon and Nikon. And DPReview confirms that in several tests.

Comment edited 3 minutes after posting

0 upvotes

Wow is it just me, or are these posts getting so technical that you need an MIT engineering degree just to keep up? where are these posters coming from. I though i knew what was going on with photography, i'm at a loss.
I think that a review should be done without revealing the camera and see what happens, then reveal the camera at a later date, kind of like a non biased camera review, and posters should give the camera or whatever item a rating of 1-10.

Comment edited 14 minutes after posting

5 upvotes

Just You !! ;)

2 upvotes

Agreed...time to go take some pictures...that process hasn't changed has it?...

0 upvotes

Do you shoot JPEG only? Then this is not for you, although you can use extended dynamic range option in camera to do the same thing.

New cameras allow ypu to underexpose to retain highlight detail. The very dark shadows in the raw file can then be brightened without much loss of quality. This can be of use in many real-life photography situations.

0 upvotes

@Mike, apparently it has changed. We are now supposed to let the camera identify the eyes for us, all you do is blink twice and the shot will be had. By 2017 they will be shipping a free French photographer with the camera, that way you don't have to do anything, you just tell Pierre what to shoot.

Comment edited 36 seconds after posting

1 upvote

DPReview, please forward this article to Sony. Right now.

I've said in a previous article that this was a "perfect example on the RAW compression subject". Glad to see you've picked it up again, with a more in-depth explanation.

1 upvote

@DPR don't you think these magniloquent articles for Sony are a little over sonorous?

I like what Sony is doing, but I also appreciate what other manufacturers are doing. Keep it balanced please!

5 upvotes

Why don't you read it before commenting?

7 upvotes

@Rouse... it beats magniloquent comments wouldn't you say?

I get your tongue-in-cheek comment, but the fact is the article goes into depth on the single biggest flaw that the A7Rm2 has. This is important as it shows Sony that potential buyers care about this flaw in what could very well be the best consumer camera ever made. I am an enthusiast but the only reason I haven't bought this camera is because of this issue. Maybe it's fixable in firmware, maybe not.

You might not care, but I guarantee there are plenty of us that do. Furthermore, DPR can ONLY keep it balanced if the "other manufacturers" are keeping up with new and exciting product development - which clearly, they are not.

3 upvotes

To what degree is the non lossless raw to do with Sony's split ADC approach ? Is this some strange complicating factor?

As to other manufacturers keeping up, why are those Toshiba/Aptina sensors used in Nikon cams pretty nice as well OR that FujiFilm are offering a 'real' electronic/global shutter ?

4 sec. to 1/32000 sec, faster than any Sony cam shutter, NO ?

Odd Sony does not have it all, do they ?!!

Objective thinking cleanses the soul !?

0 upvotes

I really wanted to edit the comment because it needed clarifying, but couldn't figure out how to on this mobile devise, then work took priority. Now clarification would just be seen as little more than a pathetic backpedal. So lets just keep talking about the only camera maker on the market doing anything because apparently the fools are believing it!

1 upvote

So, it's like decades before... if you buy a Sonyproduct you get most likely one of the best techniques, but with a horsefeet on it. I bought my videocam and got Memorystick only back in the 90s, I got my Bravia and had to get Sony to Realworld connectors just to plug in my peripherals. This time we pack together a good sensors with a lossy RAW ;)

6 upvotes

It is clear that ISO 100 is not sufficient enough light for low light shooting. ISO 800 or more is much better result I tried when I download your raw file. The ISO 100 the shadow is clipped so badly it is impossible to recover nicely and end up with rear end ugly artifacts. So I tried the ISO 800 and had no problem recover the shadow with ease and no artifacts were observed. I did not need exposure push at all, it looks good. It demonstrates that ISO 100 is useless anyway for low light, I prefer higher ISO as a result for better recoverable of shadow in particular and less noise in shadow with lower recovery amount so it looks much cleaner. That's for low light photography. Interesting post though. Thanks for showing that. I think it is totally unnecessary to have 14 bit raw file usually if I were to use higher ISO for low light especially starting from 800, that's more than satisfied enough.

4 upvotes

Rishi, thanks for the fine article. One question: Do you expect the Studio Comparison Tool for DR will be changed from fixed ISO with underexposure by faster shutter speed (plus corresponding PP pushing) to your method here of fixed shutter speed with underexposure by decreasing ISO (again, with corresponding PP pushing)? Thanks.

Comment edited 24 seconds after posting

0 upvotes

Rishi,

I think you've got about 75% of readers misunderstanding what you are trying to convey here. Maybe another intro paragraph to the article making it more simple to understand? Your mix of lossy raw and underexposure discussion is confusing.

3 upvotes

Was lens shading correction turned on? There seems to be some strange artifact around the corners in the lower ISO files that contributes to the noise. When I have shading correction turned on the raw files from my NEX-5N have a similar thing going on. If it's not that perhaps it's the lossy compression.

The performance seems very good for a 42mp sensor and 5 stops should be way more than most people would need to push shadows anyway, I often go about 1 stop and the shadow slider to full with files from my NEX and that's enough to lift almost black parts into midtones, when the same adjustments are applied to the iso 100 Raw it's very clean indeed, as good as or better than my 16mp NEX which is a pretty big achievement for a 42mp sensor!

2 upvotes

As a service to the community and a research project at the University of Kentucky, I've been working on a free program to credibly repair the artifacting in ARW2 files. I asked for aligned training images differing only in exposure at http://www.dpreview.com/forums/post/56345899 , and have gotten some from various cameras. However, I also can use the above type of ISO sequence for training. I'd like DPReview's permission to use the above images for this purpose and, with appropriate citation, in any scholarly publications on the topic.

PS: The repair algorithm isn't quite good enough to be posting yet... hopefully within the next week or so I'll post a link here and/or in the FF Sony E forum.

8 upvotes

The tool still isn't ready for posting, but here are two crops from the above ISO 100 raw data that show the repair quality is fairly good:
http://www.dpreview.com/forums/post/56389545

1 upvote

Thanks for pointing us to your work. Interesting.
According to Sony, may soon become obsolete (when they fix their ARW format), but still an impressive piece of work.

0 upvotes

This is good information and not generally seen. Excellent work, Rishi. DPR, give this man a raise!

8 upvotes

Such tests have been posted by forum members since the Sony A700 and A900 in the Sony A Mount forum, and Nikon forums readers should also be familier with similar work. Nothing new. Good to see that the Dpreview staff have started testing real life dynamic range though! :-)

Comment edited 7 minutes after posting

1 upvote

@Magnar, you are right, but before Rishi, the technological expertship of DPR staff sometimes lagged a bit behind their readers ;) No more :)

Comment edited 14 seconds after posting

1 upvote

@Falcon, you wouldn't know it by reading the forums. Sift through E mount sometime, if you believe them, there is NOTHING wrong with Sony files, it's a myth. Compression issues are not seen in real world shooting. Right?

0 upvotes

Actually, the vast majority in the E mount forum accept that there is an issue. The discussion is not wheter the artifacts exist or not, but how this affects real world photography. For me, something like a slamming mirror is much more harmful that lossy compressed raw files when using long telephoto lenses and telescopes, and also when I am doing macro stuff. Depends a lot on how you are using Your camera. And yes! You are right! The compression artifacts are not seen in real life shooting unless the files are pushed a lot! For those of us who are using low ISO/pushing techniques for night scenes/astrophoto know very well the risk. We rarely see the artifacts. Still they exist! ;-)

1 upvote

I love it when people say "SLAMMING MIRROR!!". I get this mental image of a dump truck hitting a wall at 100mph. Back in reality today's mirrors are often dampened very well. My K3 for example is very quiet and you can hardly feel any movement. My GX7 had more internal vibration with just a shutter.

As for the artifacts they are often and important enough for Rishi to write up an extensive article on it no?

0 upvotes

For long telephoto/telescope/microscope and much macro work mirror shake actually causes VISIBLE loss in sharpness. I often do such work. Even shutter shake is a problem! There is a significant and visible difference even when locking up the mirror and using ordinary shutter vs Electronic first curtain shutter. When not locking up the mirror and using shutter speeds in the range of 1/2 to 1/250 sec, sharpness is seriously affected for the work mentioned. Just test this yourself - easy, and the result will speak for itself!

Comment edited 38 seconds after posting

0 upvotes

Check out the two tree trunks on the left hand side. Notice the one without a light behind is fine, the one with the bright shop window behind is barcoded.
Who would come up with an algorithm that compresses the more noticable details in an image? Its a ludicrous compression scheme for a photograph especially when the size reduction of the file is so small.
You do need a high dynamic range scene with high contrast edges to see it but the camera would be capable of tackling these scenes without the compression issue. Took the shine off for me when I found a very strong example of the issue in the first week with the camera (visible with far less of a push than here).

6 upvotes

Take it down to print view and it is still noticeable to.

2 upvotes

"quantization noise due to insufficient ADC bit-depth" for D810, would you suggest Nikon to use 15/16-bit ADC to improve quality for their new cameras?

What is the minimum ISO of D810 that is ISO invariant?

How to do a +6EV push in ACR? I could only do +5EV.

Thanks

1 upvote

Would you mind sharing your optimal ACR settings? I downloaded the ISO 100 file and no matter what I did, the image was riddled with noise by +2 when looking at it 3840x2160. I can't post an image here, but did you realize there was a bum laid out in the store's entryway?

2 upvotes

"Riddled with noise", as in more than what's shown in their images? I can't get +6 exposure in ACR, but with +5, -50 highlights and Tungsten WB, it gets me almost exactly to what's shown in the images above, including noise. All other settings were default, including NR (25 Color, 50 Detail, 50 Smoothness)

1 upvote

I'm with Rick, same story on 4K screen so easily can see how noisy it is. Not sure whats up with this?

1 upvote

Well there's a probably homeless person in the doorway. No need to denigrate when their story isn't known.

1 upvote

bum /bəm/ noun North American

1. a vagrant.

He's looking pretty vagrant to me.

1 upvote

I picked up the phrase 'riddled with noise' from a Nikon/Sony troll describing 5DsR images on the Canon forum. This image is very similar to the Canon image so...

4 upvotes

judging by peoples lauding RAW strengths (Sony ARW) for pp
if the ARW shadow recovery benefits differ only by a little bit from Sony ooc jpegs

here:
http://www.dpreview.com/forums/post/56372417
http://www.dpreview.com/forums/post/56372472

wouldn't Sony ARW (cooked) RAW just be a slightly (mathematically) stretched (less compressed) kind of lossy JPEG (can manipulate more than 8-bit jpegs) whilst not officially a jpeg (it isn't 8-bit; therefore not jpeg by definition)? right?

are there lessons for RAW-only shooters here?

I can't be sure why ooc jpeg would be so high contrast (why darks too dark in full daylight) even with the sun (well above horizon) properly exposed (far brighter than a night time store lit display, right?!). why not just dial contrast down in camera so ooc jpegs aren't rendered unrealistically dark?!

Comment edited 6 times, last edit 14 minutes after posting

0 upvotes

No the two aren't comparable (RAW & JPEG). I shoot weddings with an A7 and I shoot indoors so at high ISO like 1600 and more. Whenever I clip the highlights (which happen very very often) with RAW I can pull back a pretty substantial amount of detail.

JPEG has very little headroom to pull back clipped highlights. A one stop clip is enough to destroy any detail in the highlights when brought back. With RAW I can pull back detail from 2 to 3 stops over exposure.

4 upvotes

I think you miss my point.
true unaltered RAW show exact highlight clipping (and sunk shadow clipping)
cooked RAW overlays a 'rendered contrast' or 'rendered gamma' that should not be there to begin with.

darks that aren't really at black point are overexaggerated with too dark darks (not really black blacks)

brights that aren't really at white point are overexaggerated with too white brights (not really white whites)

initially digital RAW images were very flat, with unaltered gammas, regardless of over or under exposures. this confused users used to film era contrast found in positives (slides) and negatives (print papers, etc)

today, dcam mfrs (and software app mfrs) have opted to precook the look of RAW with altered (exaggerated) contrast to mimick film contrast

keeping in mind, FILM contrast NEVER matched reality, ever.
I.e. shadows never look pure black in broad daylight, indoors, or night to our eyes, it was a phenomena of film, which digital is mimicking, to acclimate users

Comment edited 2 minutes after posting

0 upvotes

basically, flat RAW (true RAW) is returning, initially for pro Cine users, whilst flat RAW is SLOWLY returning for prosumer still users in terms of flatter contrast/gamma profiles.

adjustable previewable live contrast/gamma (DR rendering) for in camera jpeg engines have always been around, even though not all camera mfrs offers it fully (or partially, or none at all).

Comment edited 28 seconds after posting

0 upvotes

Article

Sony Alpha 7R II: Real-world ISO invariance study

Preface

ISO-invariance

Raw Compression

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