5.04.2012

Forget ISO 25,000. I'm loving what I'm seeing at ISO 50.


Note to all technical geeks:  I assume that the "native" ISO of a sensor is where it gives you the greatest dynamic range coupled with the cleanest file.  For the a77 DXO clearly shows on their graph that it is squarely at 50 ISO.  They're pretty smart so I don't really give a crap about anyone else's presumptions or conjecture.  And...I've shot at 50 and 100 and 200 and 50, by far, looks the best.  Sorry if the science fails you.

Many times over the past few years of writing about cameras I've made the statement that I'd prefer a camera with the ability to do a "real" ISO 50 over a camera that does infinitely high ISO files.  Here's the reason:  Most of the work I do is completed under controlled lighting and in commercial work the bulk of it is done on a tripod.  While 50 ISO may not work as well for moving people shots with LED panels I've still got a studio full of nice electronic flash gear I can press into service when I want it.  A "real" ISO 50 (as opposed to the "pulled" ISO 50 on the Canon cameras) can be the highest resolution and lowest noise setting on a camera with a sensor designed for detail.  And the added benefit in the case of the Sony a77 (as confirmed by DXO and this Dutch website: http://camerastuffreview.com/en/reviews-en/camera/85-testen/cameratest/sony-cameratest/275-review-sony-a77 ) is that this is also the setting for the widest dynamic range for that camera and sensor.  They were able to get over 2500 lines of resolution with a usable dynamic range of over 10 stops IN JPEG in their tests.  Absolutely amazing.  And the ISO's of 64, 80 and 100 are just tiny increments less perfect.

But I never take other people's test to heart without confirmation at my own hand.  After a week of shooting nearly 1,000 exposures with the a77 for clients (including a bunch of very nice, clean work at ISO 800, with LED panels as primary lights ) I decided to head out this afternoon, around 4:30 and run some tests of my own.  I set the camera to Super Fine Jpeg (I've flip-flopped and decided that, in the default settings, this is the ultimate Jpeg shooting machine....but I'll explain that in another post).

The idea to test at ISO 50 came from a statement I made in a post two days ago about getting the most out of your camera.  I suggested that rather than only focus on worst case shooting scenarios when breaking in your new camera, that you also try the settings on your camera where you can expect the best case scenarios to see just what you and the machine can do.  Having written it I thought it only reasonable to head out and give it a try.  I'd already spent loads of quality time on a tripod this week, some of it down around 100 ISO so I had an inkling of just how sharp and how much resolution the 24 megapixel files have.  In a word, at that setting, better than a $3,000 Canon 5DMk2.

I also wanted to do a test of my newest lens, the Sony 35mm 1.8 DT lens.  It's a lens that's made to cover only the image circle of an APS-C camera and it's made out of plastic materials but according to everyone else's test it's a really sharp optic.  Especially in the center of the frame.


Today was our "get used to Summer" day here in Austin.  The mercury hit the 95 degree mark.  A bit hotter downtown... 

I set the camera at ISO 50, turned on the Steady Shot IS, set the AF to spot, and the image file setting to Standard.  And away I went.  I even got fancy and put sunscreen on my face.  My concession to the relentless Texas sun.  I shot everything.  EVERYTHING at f4.  I figured that would be the sharpest setting.  Two stops down from wide open.


The combination of the slow ISO, the optimum aperture and the overwhelming resolution of the camera make for files that can be enlarged and enlarged without every showing grain, noise or lack of sharpness.  It's like shooting MF digital  (and yes, I have tested and reviewed three of the four major brands of MF digital cameras in the last three or four years...)  the performance at the lowest ISO is worth any of the other compromises in the camera.  I conjecture that, putting the camera on a stout tripod and adding in Multi-Frame Noise Reduction you have a fighting chance of rivaling the new D800 for ultimate, on paper print performance.  I'll test it soon and find out.


This is my new hat.  I think it's cool.  When I went to an ASMP breakfast this morning a very cool guy named, Destry, had one just like it.  Since he is nearly half my age I took that as a certification of coolness.  At any rate it came with me on my walk and sat next to me as I had a cappuccino (again, one of the finest I've ever tasted) at Medici Caffe on Congress Ave.  The shot is cool to me because it's taken at 1/13th of a second and it's incredibly sharp.  Shooting ISO 50 indoors.  How chic?  And it would give you prime glass shooters the opportunity to spend more time at the interesting side of the aperture ring....




I've often said that Austin is a wacky town.  These guys were driving around in the van with the side door open, filming who knows what.  They stopped at the traffic light and I photographed them as I walked into the cross walk.  No one else even batted an eye.  Weird stuff happens so continuously in Austin and most people are inured to it after a few months.



This is my perennial test building.  I blow it up on the screen and look at the bricks. If I can read the brick maker's logo I know I have a high resolution tool in my hands.


When I got back to the studio car I remembered that I'd left the top down.  I'm glad it didn't rain.



My final shot (above) is a person at an outdoor bar on sixth street.  She is standing in front of a fan and occasionally the fan sprays out a mist of water for that "evaporative cooling" effect.  She was gracious enough to re-pose because she was about to walk off when I found her.

Remember the days before everyone wanted their camera to be the Swiss Army Knife of cameras and to be good at everything (impossible)????  We had cameras that took big film for landscapes and images that would go up large.  We used em with slow film to maximize the effect.  We had our snicky little Leicas with impossibly fast lenses, and pushed film, for the stuff we needed to shoot in the dark.  We had the best of both words by using specialized tools.

I'm right there with the new Sony cameras.  The a57 is a low light champ with 16 nice megapixels.  The a77 is my studio, low ISO, super res camera.  And I have one more thing that none of the Canon and Nikon shooters have yet.  I have a beautiful EVF finder.  The only 21st century technology, professional camera system out there.  

It doesn't really matter what brand of camera you have.  You might try using it at it's lowest "real" ISO and using good technique.  You might be shocked at just how good your gear can be.

EDIT FOR ALL THE STRANGE PEOPLE ON FORUMS.  While you may "want" the base/real ISO of the Sony a77 to be whatever you want it to be I'm going by the material I read at DXO Mark.  The info shows the highest DR and the lowest noise at ISO50 which is NOT a menu extended ISO but a marked ISO.  This would explain the lower (by one stop) noise performance at the top ISO as well.  If 100 ISO were the real sensitivity of the sensor I think that's where you'd see the top DR.  And unlike many who would rather argue than test for themselves, I've actually shot comparisons between 50, 64, 80 and 100.  50 is better.  On all counts.

To the wag who suggested that I must be using Sony cameras now because, "Nikon Stopped Giving Free Stuff to Kirk.."  I'll reiterate what I've disclosed here time and time again:  We pay real, hot American money that I earn from writing books and shooting assignment photography for almost 100% of the cameras I write about and review.  We note all exceptions.  The one camera I received free of charge was an Olympus EPM-1 (the lower part of the product range) as part of their "GetOlympus" promotion.  While I would love for Sony and Nikon and Canon and Olympus to send me free, top of the line cameras, in reality I pay for them just like everyone else.  



18 comments:

atmtx said...

Kirk, I'm not sure but something tells me that you like the Sonys.

Dennis said...

Just a technical note on ISO 50. When the SLTs first came out, everyone was aware of the 30% light loss and the fact that the camera had to "gain up" the signal to provide the same brightness. So at ISO 100, you'd get slightly noisier images from the A55 than from the A580 for instance. Some wondered why not provide a way to tell the camera to effectively "turn off" that automatic gain ... in other words, rather than shoot at an ISO 100 that's gained up like a higher ISO, shoot it at "real" ISO 100 and meter accordingly; let me provide more light to the sensor to make up for the SLT mirrors light loss to maximize image quality.

Enter ISO 50. If you compare ISO 50 on the A77 to ISO 100 on the NEX-7 on dxomark, you'll find that the measured sensitivites are 63 and 78 respectively, which is close to reflecting the 30% light loss, and that the IQ measurements at those two settings is much closer than the gap you see when you set them to the same ISO settings.

In other words, ISO 50 on the A77 is the same base ISO 100 on the NEX-7, but requires more light to compensate for the mirror.

I applaud Sony for implementing this; it's great that you now have the option of eliminating the SLT "penalty" when you have the luxury of increasing your exposure. But you're not getting a true ISO 50.

kirk tuck said...

Dennis, is this proven or conjecture? Did Sony come out and say as much in a white paper? Because when I look at DXO's charting of DR performance by ISO it is higher at 50 on the a77 than 100 on the NEX-7 which throws a logic wrench in all the SLT penalty talk. I'd like to see where Sony says they res up the files. I think it sounds like a logical explanation and so is widely embraced but I am not sure it is fact. Regardless, the a77 is remarkably noise free and well endowed with DR at what I believe is a true ISO 50.

Dennis said...

Hi Kirk, thanks for taking the time to look, and I apologize for not being clear that this is conjecture on my part. However, I'm seeing (on dxomark) SNR, tonal range and color sensitivity measurements that are virtually identical for the NEX-7/100 & A77/50 and DR being higher on the NEX @ 100:
NEX-7 at 100 has a measured sensitivity of 78 & 13.39EV DR.
A77 at 50 has a measured sensitivity of 63 & 13.15EV DR.

I don't think Sony has ever stated that they gain up the signal on SLTs ... but how else would they do it ? (How do you get the same brightness out on an SLT at the same settings if you're losing light ?) I'm sure there are possibilities (a less dense CFA ?) But the dxomark charts suggest that the secret-ISO-boost is a reasonable explanation. We know from dxomark that manufacturers already boost the ISO to make our f/1.4 lenses behave like f/1.4 lenses even though sensors don't quite see all the light that comes in at extreme angles from those big apertures, as they described in their "F-stop blues" article:
http://www.dxomark.com/index.php/Publications/DxOMark-Insights/F-stop-blues

In any event, I've looked at a few ISO 50 A77 files and without taking the time to compare for myself whether they're different from NEX-7/100 files, I agree that they're really impressive.

Ken Hurst said...

I'm going to have to make a trip to Austin and check out the cappuccino at Medici Caffe and take photos of weird stuff.

dario sartini said...

Well, it seems that you are quite satisfied by the new sony toys (that sounds music to a happy NEX-5 user like me), however I would appreciate if you (or Dennis) could go deeper in this comparison between NEX-7 and A-77 light sensitivity.
One more curiosity: what about your 4/3 stuff ? Are you still using it ?
Ciao
dasar

kirk tuck said...

Thanks Dennis, It is a logical explanation but the light loss is supposed to be less than half a stop. I'll try popping the mirror up like Kai on Digital Rev did and measure (without a lens on).

kirk tuck said...

Dario, Glad you asked about the m4;3rd stuff. While I am smitten with the Sonys I still pack the EP3 and the 45 nearly every where I go. It's a wonderful combination. And when all the furor dies down i look forward to playing with an OMD EM5. Seems just right.

wjl (Wolfgang Lonien) said...

Wow. You've got a nice studio car. Any comments from your CFO on that one? ;-)

efix said...

+1 on this, Kirk. I tend to shoot 95% of the pictures I take with my M8 at its base ISO of 160, which delivers files with outstanding tonality, colour reproduction and dynamic range. Such a joy to pixel-peep and tinker with in pp!

rlh1138 said...

So you smart guys all know that the lowest ISO on a camera may not be its 'real' lowest ISO - OK - I missed that memo. (And lots others) Could someone save me a lot of google time and tell me what is the 'real' low ISO on my Sony R1???

Thx,

Ray H.

kirk tuck said...

160 ISO. And man is that ever a great camera. I still have and use mine. Great lens and great sensor.

kirk tuck said...

Our CFO was so happy we replace the Veyron. It was expensive to maintain... :-) I guess you just have to expect that from a Bugatti.

Travis said...

I think when you get your hands on an E-M5 you'll fall in love with it for what it is, and it may well replace your EP3. It's barely bigger, and the new IBIS really is that good so far as I can tell. It easily feels as good in the hand as the EP3, and I love having two usable control dials again.

And all that is to say nothing of the image quality, which is really really good.

Scott said...

I find that the Mercedes Estate cars are more practical for hauling equipment, although they ARE a little down-scale for you.

It's also cool that you can leave the Bentley's top down in Austin and not have the seats stolen. Like living in a movie.

kirk tuck said...

Austin downtown and most of the west Austin neighborhoods don't seem to have so much crime. Certainly not like bigger U.S. cities where you leave your glove box open so passing criminals can quickly assess that you don't have enough in your car to make robbing you efficient. I see a number of convertible Bentleys, Aston Martins and even Ferraris open and parked around downtown. The Bentley I photographed has two leather bags left unattended in the back seat and no one seemed in a rush to liberate them...

Not such a bad place to live...

Brad C said...

As much as I love MFT, trying to use the 'interesting side' of the aperture ring is tricky in bright sun. You only have ISO 160 or 200 to work with, and a little bit lower max shutter as well. Time to get an ND filter or polarizer, I guess.

ISO 50 would be handy...

Keith I. said...

I wish my NEX-7 had an ISO 50. I have really been impressed with the 24MP sensor, especially when paired with nice glass. In my case it has been the 24/1.8 Zeiss and 50/1.8 OSS in E mounts.