[clackers]

I looked this up as well one has better distortion less sharp the other is more sharp worse distortion

But that's DXOMark running software over the RAW images, SS.


You need an optical test bench to measure the true amount of distortion.

[Sliver-Surfer]

But that's DXOMark running software over the RAW images, SS.


You need an optical test bench to measure the true amount of distortion.

Digital Cameras all use software to get the info collected from the sensor to the memory card.

[clackers]

Digital Cameras all use software to get the info collected from the sensor to the memory card.

Yeah, but you can do away with the digital camera altogether.

Just test the lens, so you don't get Volkswagen-style gaming of the metrics.

[Digitalis]

that's DXOMark running software over the RAW image

Which was my point all along, Sony as usual, is being flat out deceitful. And DXO are perpetuating the lies.

You need an optical test bench to measure the true amount of distortion.

Exactly, and unsurprisingly: DxOs results are completely wrong. According to one of my colleagues who has an optics bench with an E mount lens platform: Distortion of the Sony E 30mm f/3.5 Macro - barrel distortion of 0.97% on APS-C*, my test data from the DA 35mm f/2.8 Macro (two copies tested) revealed barrel distortion of 0.42% on APS-C*. For reference: the SMCP-FA31 ASPH Limited ( 7 copies tested) has 0.7% barrel distortion on Full frame.

* Across a cropped 23.6X15.7mm area. It is important to note anything approaching or over 1% distortion will be visibly noticeable to careful observers, anything over 0.5% will be visible to experienced eyes.

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Last edited by Digitalis; 02-17-2016 at 10:18 PM.

[GeneV]

Is there a practical reason why correcting distortion optically yields a better final photo than correcting it digitally?

---------- Post added 02-18-16 at 02:10 AM ----------

Yeah, but you can do away with the digital camera altogether.

Just test the lens, so you don't get Volkswagen-style gaming of the metrics.

Why would I want to do that? I'm not buying the lens to use on a bench. I also drive a VAG product I'm quite happy with, so maybe I'm just not a purist.

[wildman]

Why [when} would I do that?

When you confuse the means with the end.

The statement "shuffle data around to make things look better than they really are"
is the logical equivalent of saying - Ansel Adam's work is not really beautiful it just looks beautiful.

[Digitalis]

Is there a practical reason why correcting distortion optically yields a better final photo than correcting it digitally?

1) you don't lose as much resolution when you apply lens corrections in post 2) Lower distortion also reduces field curvature.

is the logical equivalent of saying - Ansel Adam's work is not really beautiful it just looks beautiful.

nice straw man you've got there.

[Rondec]

Is this distortion something you have experienced or just heard about. The only Sony lens I have used which has "fearsome distortion" is the 16-50. I have not used the FF 24-70, but my Zeiss 16-70/4 on a crop format is the best lens of that range I have ever used, even raw.

---------- Post added 02-17-16 at 02:01 PM ----------



That was my reaction. I am not really that concerned with whether I have a Ferrari which theoretically goes over 217 mph if I never have a reason or a place to go that fast.

If the end result looks good, then I'm happy, but YMMV,

In answer to your question, I have just looked at lens reviews and specifically read Roger Cicala's article on his testing of Sony lenses. My personal preference would be to have well corrected optics -- particularly if I am paying for an expensive lens. There is no free lunch and when you do software correction, it does decrease resolution and some times you lose some of your borders (wide lenses aren't quite as wide).

Be that as it may, in the end, the goal is to create images that please the photographer and if you are happy with your Sony images, then that is what matters.

[Sliver-Surfer]

I will agree sony has some lenses bad distortion. But none of the ones you talk of are G-Master lenses. Ill take better Sharpness over better distortion any day of the week.

[osv]

Which was my point all along, Sony as usual, is being flat out deceitful.

no, as i posted earlier wrt imatest and dcraw, sony in-camera lens corrections for raw files can be turned off, if the raw developer software has that capability, the raw data itself is not affected, because the correction data for raw files is written into a separate parameter... see these two links, from the same author:

"I think you’re mixing 2 different things. I believe Jörg’s diagram is correct.
– LR takes its lens distortion correction from its database of lens-profile files. That’s what you’re applying in the “Lens Correction” module.
– However, Sony also embeds its own lens correction information in the ARW-file (SR2SubIFD tag 0x7982, mirrored in Exif SubIFD tag 0x7037 – it’s written independently of your off/auto setting for distortion correction), which LR then chooses to completely ignore. Interestingly, when you run the ARW through Adobe’s DNG-converter, it writes the information into an XMP-tag (“LensDistortInfo”). Meaning, it does read the information but doesn’t use it.
For CA, it’s the opposite. The equivalent tag in the ARW is always interpreted by LR, no matter your camera setting.
I documented my findings on this a while ago at https://variousphotography.wordpress.com/ if anybody is interested in digging deeper." In-camera lens compensation | JÖRG HAAG

-------------------------------------------------------------------

"Here’s a summary of what I’ve found on regarding the lens-correction data that Sony embeds in their ARWs. This is tested with a Sony A7 (ILCE-7) and the Sony/Zeiss 35mm F/2.8 and 55mm F1/1.8 lenses. I would believe that this also holds for other cameras using v2.3.1 of the ARW format (e.g., A7r, A7s, A7m2) but haven’t tested it.

The A7 allows to separately set 3 possible corrections in the menu (‘Auto’ vs ‘off’).
Vignetting correction
Chromatic Aberration correction
Distortion correction
Not every lens seems to support all modes, my 55mm has the distortion correction greyed out to ‘Auto’, so it can’t be switched off. However, Sony is embedding the data into the ARW in any case anyway, no matter the setting (at least for CA/dist, probably also Vignetting). It’s up to the software to decide if to use it.

Also interesting is Adobe’s take on this:

Lightroom automatically applies CA correction and the DNG-converter writes CA-correction opcodes into the DNG-file.
Distortion correction is not applied in Lightroom. However, the DNG-converter writes an non-standard XMP-tag into the DNG-file that saves the decoded correction data. It does not write distortion-correction opcodes (although they’re part of the DNG-spec), so other DNG-readers won’t apply lens-correction either (unless they interpret Sony’s MakerNotes on their own).
As far as I can tell, Lightroom and the DNG-converter completely ignore any Vignetting correction information. https://variousphotography.wordpress.com/

---------- Post added 02-18-16 at 10:28 AM ----------

1) you don't lose as much resolution when you apply lens corrections in post

sony raw lens corrections are always applied in post, the camera does not alter the actual picture data itself, see above.

[Digitalis]

Ill take Sharpness over distortion any day of the week.

and you will probably end up with both.

[petrakka]

If we were talking about food, then I need the best raw ingredients possible. No BS from the manufacturers, I want everything organic and unadulterated, I am putting that stuff in my belly for Christ's sake.

But with photographs, I don't care how they get made, and I don't think most photographers do either - they are just tools. I don't care if it uses a cardboard lens and scotch tape and then the rest is all just algorithms and processing - if the file looks good and I can use the tool to get the ideas from my head onto prints or into pixels, that's what I care about. I don't understand this debate - it's subjective. Lens sharpness ratings may not be subjective, but lenses are not sold with sharpness ratings as their intended final use. Their intended use is to be the first half of a picture making machine and to help make pictures, where sharpness ratings are really, really, just really not very important in the vast majority of applications - as long as the lens meets a basic level of quality, which all of these do. If people like the look and the images that the Sony or Zeiss lens / camera combination turns out then, well, what's there to argue about?

[philbaum]

I'm a bit cynical about purity. It seems to often that purity, i.e. thats the way its properly done, has been used as an excuse to maintain the status quo. In Ansel Adams day, one would use an optical enlarger to change the size of a picture. Today, we use digital algorithms to resize an image and few people argue about it.

I don't know much about the tradeoffs between optical and digital correction, but i believe that the more optical correction that occurs, generally the more elements and groups and therefore a reduction in light transmission so thats a tradeoff. I think, don't know for sure, that the weight and size of lenses (and camera bodies) is an important factor to a sizable number of customers. For example, every photographic forum gets those chronic posts about traveling where the OP wants to know a lightweight easy carrying camera system for this vacation trip or that everyday need, etc. Every Sony forum also gets occasional posts where someone who doesn't want to carry their heavy/large canikon bag anymore and wants to get a lighter system. My point is that lightweight/small lenses represent a market niche if a mfr can exploit them, e.g. Pentax's pancake lenses. (of course, not everyone wants a lightweight system, but thats a different niche)

The Sony 28 f2 and 55 f1.8 are 2 lenses that are always in my bag or on the camera because of their lightweight and excellent IQ - i don't care how they were corrected so long as the images look good when printed to 20"x30".

[wildman]

i don't care how they were corrected so long as the images look good when printed to 20"x30".

Or to put it another way...

... any difference that makes no practical real world difference is no difference.

[Digitalis]

For example, every photographic forum gets those chronic posts about traveling where the OP wants to know a lightweight easy carrying camera system for this vacation trip or that everyday need, etc. Every Sony forum also gets occasional posts where someone who doesn't want to carry their heavy/large canikon bag anymore and wants to get a lighter system. My point is that lightweight/small lenses represent a market niche if a mfr can exploit them, e.g. Pentax's pancake lenses. (of course, not everyone wants a lightweight system, but thats a different niche)

Just because someone wants a supercompact gutless optical wonder doesn't mean the rest of us have to suffer for it. In the end: we all shoot the glass we deserve, because of the compromises we are unwilling to make. I haul some pretty heavy lenses even when I'm traveling: It is a price I pay, and I pay it gladly, because I know my lenses are the best - they won't let me down.