Monday, April 3, 2017

With The Fuji X-T2, Can You Now Standardize On ISO 800? What Do You Gain And What Do You Lose?

Fuji X-T2, 16-55mm f/2.8 lens @ 47.2mm; 1/50th sec. @ f/11; ISO 800
A well know professional photographer recently mentioned that ISO 800 is his base ISO on the Fuji X-T2.  He said that he sees no difference in quality between ISO 200 and ISO 800. I found that comment interesting so I thought I would look into that concept for myself. Here is what I found.

 If you are looking for optimum image quality, stick to ISO 200.  I've found that ISO 200 has the lowest digital noise profile, the widest dynamic range as well as the most accurate color reproduction.  However, if you find yourself consistently needing faster shutter speeds or more depth of field than your circumstances normally provide, then you have to decide what is more important, making the image as you need it or dealing with a bit more digital noise and a bit less dynamic range.  At ISO 800, the sensor produces the same amount of noise as ISO 320 (but more than ISO 200), according to the website Photons to Photos.  See the graph below.  The price you pay for routinely using ISO 800, however, is reduced dynamic range from approximately 10* stops to just over 8 1/2 stops.  You lose almost a stop and a half of dynamic range, again, according to the website Photons to Photos.
X-T2, 16-55mm f/2.8 lens @ 47mm;
 1/20th sec. @ f/16; ISO 800

 Take a look at these two graphs I constructed from Photons to Photos.

Note:  I attempted to contact Mr. Claff to ask permission to use the graphs I built on his site using his data.  However, I have not been able to do so.  I decided to use the graphs as a teaching tool under the Fair Use doctrine of the U.S. Copyright laws.  I am not a lawyer but I have found it necessary to understand copyright law and there are exceptions for use of copyrighted material, one of which is for educational purposes, which is what my use is here on my blog.  If Mr. Claff contacts me and asks me to remove the graphs, I will gladly do so. Until then, I think the graphs below are good illustrations of the what is under discussion here.  Again, I give full credit and copyright ownership to Mr. William J. Claff from Photonstophotos.com.
Educational Use Only; ©William J. Claff, Photonstophotographs.com; (click to enlarge)
Educational Use Only; ©William J. Claff, Photonstophotographs.com; (click to enlarge)

*Photons to Photos indicates the Fuji X-T2 has a maximum dynamic range of approximately 10 stops.  I don't have any empirical evidence, but my subjective judgment, after using this camera extensively in all types of situations over the past 7 months is that the dynamic range is greater than 10 stops.  I would put it near 12 or so.  However, I cannot dispute his findings with my own data so I am presenting his data so you, the reader, can be as educated and informed as possible.
Fuji X-T2, 50-140mm f/2.8 lens @ 106mm; 1.9 sec. @ f/11; ISO 800; 10X ND filter
I don't see a problem using ISO 800 routinely, as long as you are not photographing in situations which require extensive dynamic range.  To me the loss of dynamic range is much more important that a small amount of additional digital noise.  With that small amount of additional digital noise Fuji files contain at ISO 800, I really don't worry about that at all.  As far as color reproduction is concerned, if there is any difference, it is minor and most likely can be corrected/adjusted with your editing software such as Lightroom CC.

Utilizing ISO 800 seems to be a good compromise ISO to choose if you need a higher ISO for faster shutter speeds and/or more depth of field since the noise profile dips significantly at that point.  ISO 800 gives you two additional stops of shutter speeds or the ability to stop down two additional stops for more depth of field with little penalty.  With today's sophisticated editing programs, the additional noise can be mitigated easily, in my opinion.
X-T2, 16-55mm f/2.8 lens @ 36.5mm; 1/50th sec. @ f/8;
ISO 800
Again, after hearing about a professional photographer utilizing a higher ISO routinely, I did a bit of research just to find out what is what.  I made several images using ISO 800 and was pleased with the results.  

 As always, I like to share my experiences with you so you are armed with the best knowledge and understanding of your gear.

 Thanks for looking. Enjoy! 

 Dennis A. Mook 

 All content on this blog is © 2013-2016 Dennis A. Mook. All Rights Reserved. Feel free to point to this blog from your website with full attribution. Permission may be granted for commercial use. Please contact Mr. Mook to discuss permission to reproduce the blog posts and/or images.
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4 comments:

  1. AnonymousApril 3, 2017 at 11:31 AM

    Dennis,

    since the Fuji has an ISO-less sensor, and I think you had run tests showing little/no difference in shooting at base ISO and adjusting exposure in post-processing vs adjusting ISO at time of exposure, (assuming I have it right so far) wouldn't it make sense to just forget about using ISO and dealing with it in post? One less thing to worry about? If so, perhaps dynamic range might not suffer as much (another test to run :)

    Rick

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    Replies
    1. The Wandering LensmanApril 3, 2017 at 2:44 PM

      Rick, you are correct. From my testing, one will get similar results if either one increases the ISO on the camera so one's exposure is where it needs to be or leaves the ISO on the camera alone, sets exposure where it needs to be, then corrects the file's luminance in editing. However, there is a point, and I can't remember exactly at what ISO it is (may be 1600) that making the changes in-camera actually produce a better quality image. I will have to go back and check when I have a chance. For most cases in the two options above, in my experience, the final image results are identical.

      This morning I was out photographing the last local run of the Ringling Brothers and Barnum and Bailey Circus train. The train was running SE to NW with the sun coming from the southeast. A challenge. Anyway, I calculated I only needed 1/500th sec. @ f/11 as my desired exposure to stop the train's movement as well as for adequate depth of field, as the train was not moving very fast. The front of the train was in full shadow. I set my exposure as I needed it, saw that I needed at least ISO 1000 to have a proper exposure, so I just underexposed the images and corrected in Lightroom. They are fine.

      The anomaly, according to Photons to Photos, is that a camera setting of ISO 800 produces less noise for some reason. Maybe that is why that pro said he uses tha ISO for most of his photography.

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    2. P.L.April 5, 2017 at 6:13 AM

      Fuji has the "DR 400%", and it needs iso 800 to be that high. (iso 200=dr100% and iso400=200) How will that work with your "loose 1.5 stops of dr in 800"?

      Regards
      P

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    3. The Wandering LensmanApril 5, 2017 at 9:30 AM

      P.L., thank you for your comment.

      My understanding of how the Fuji dynamic range, DR 100-200-400, works is that when you set your camera for 200 or 400, or the camera sets it automatically if you enable the "auto" setting, the camera essentially reduces the exposure to maintain highlights but then electronically boosts the shadows in-camera. I don't think you get any more dynamic range in reality, just bringing up the shadows as you could in your editing program later.

      If anyone reading this knows differently, please share that information with all of us so we can benefit.

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