DPR Forum

Welcome to the Friendly Aisles!
DPRF is a photography forum with people from all over the world freely sharing their knowledge and love of photography. Everybody is welcome, from beginners to the experienced professional. Whether it is Medium Format, fullframe, APS-C, MFT or smaller formats. Digital or film. DPRF is a forum for everybody and for every format.
Enjoy this modern, easy to use software. Look also at our Reviews & Gallery!

My High ISO Evaluation

Steaphany

Well-Known Member
Even though I'll be posting a number of photos to this thread, I'm posting this here, under "Sigma Cameras" since the focus will be on how the SD14 performs through out the available ISO range.

Being inspired by akv's thread Salt Shaker where the image was photographed at ISO 1600, I decided to experiment with my SD14 and see exactly what can be expected.

Earlier this morning, as several of my Horses were playing front yard gardener, I went out and shot a series of photos keeping as much possible the same while only varying the ISO through out the 50 to 1600 range. The sky was blue with few clouds, I had my SD14 set to Shutter Speed Priority, Sunlight White Balance, 1/320s Shutter Speed. These photos are pretty much snap shots with the only composition being an attempt to ensure a consistent angle between the Sun and my subject. I specifically chose not to perform post processing in preparing these photos for inclusion just so everyone can see what the SD14 base line performance is. Here are the photos:

ISO 50

View attachment 1511

ISO 100

View attachment 1512

ISO 200

View attachment 1513

ISO 400

View attachment 1514

ISO 800

View attachment 1515

ISO 1600, Since my 28mm lens could only go down to f22, I raised the shutter speed to 1/640s

View attachment 1516

So far so good, no significant noise, and the only obvious difference is a apparent reduction in color saturation.
 

Attachments

  • SDIM0137ISO50s.jpg
    EXIF
    SDIM0137ISO50s.jpg
    230.5 KB · Views: 19
  • SDIM0138ISO100s.jpg
    EXIF
    SDIM0138ISO100s.jpg
    239.2 KB · Views: 17
  • SDIM0139ISO200s.jpg
    EXIF
    SDIM0139ISO200s.jpg
    229.3 KB · Views: 16
  • SDIM0140ISO400s.jpg
    EXIF
    SDIM0140ISO400s.jpg
    226.9 KB · Views: 23
  • SDIM0141ISO800s.jpg
    EXIF
    SDIM0141ISO800s.jpg
    204.4 KB · Views: 27
  • SDIM0143ISO1600s.jpg
    EXIF
    SDIM0143ISO1600s.jpg
    211.2 KB · Views: 33
These photos actually surprised me, so I pulled out my X-Rite ColorChecker card, shot another set and proceeded to code a spread sheet to perform some actual comparative calculations. I chose a shutter speed of 1/500s which allowed it to remain constant across the full ISO range.

Using the documented sRGB Red, Green, and Blue values as a base line and computing how the "as photographed" ColorCheck RGB color values differed from the ideal, I have come to some interesting conclusions.

Through out the ISO range, the SD14 delivers a constantly higher color saturation, while the mean luminance was within an acceptable range to the X-Rite ColorChecker expected values. These average errors were computed by comparing the SD14 performance to the X-Rite standard and averaging the results of all 24 color samples. Please note that my spread sheet calculated a wide range of results across the 24 ColorChecker references:

Code:
ISO   Mean Saturation Error   Mean Luminance Error
50     54                             3
100    62                             1
200    62                             1
400    55                            -5
800    46                            -4
1600   44                            10

Interestingly, the individual color channels also show a consistent bias towards boosting the Red while also suppressing the Blue:

Code:
ISO   Mean Red Error   Mean Green Error   Mean Blue Error
50     16                    4                        -1
100    14                   8                         -6
200    13                   12                       -8
400    5                     8                        -16
800    5                     12                       -14
1600   19                   29                       0

This effect has been discussed at length in the thread SIGMA's Garish Red Problem ...

When comparing the error of individual Primary color squares, squares which are strong in the Red, the Red and Yellow squares, have a consistently have a boosted Red with a reduced Blue while strong Blue, Blue and Cyan, results in the opposite effect regardless of the ISO.

The image quality was acceptable regardless of ISO and surprisingly, there was no significant color noise even in the dark regions of the ColorChecker card.

Here are the photos:

ISO 50

View attachment 1517

ISO 100

View attachment 1518

ISO 200

View attachment 1519

ISO 400

View attachment 1520

ISO 800

View attachment 1521

ISO 1600

View attachment 1522

Seems like we may be able to find situations where the high ISOs may be useful.
 

Attachments

  • SDIM0161s.jpg
    EXIF
    SDIM0161s.jpg
    321.1 KB · Views: 9
  • SDIM0160s.jpg
    EXIF
    SDIM0160s.jpg
    325.5 KB · Views: 10
  • SDIM0159s.jpg
    EXIF
    SDIM0159s.jpg
    319.7 KB · Views: 10
  • SDIM0158s.jpg
    EXIF
    SDIM0158s.jpg
    313.9 KB · Views: 12
  • SDIM0157s.jpg
    EXIF
    SDIM0157s.jpg
    306.9 KB · Views: 13
  • SDIM0162s.jpg
    EXIF
    SDIM0162s.jpg
    310.7 KB · Views: 22
Good work Steaphany, I'm glad that my picture inspired! For good I hope! lol :D

I mostly use the high ISOs for black and white images in low light, like the salt shaker image.
In the horse pictures, the 100-200 ones were most pleasing to my eye. The 50 ISO had the shadows too dark, and in the 800 image I could really notice a magenta tinge to it. The 1600 was surprisingly pretty clear though.
In the color chart pics, the 1600 ISO looks a little "washed out", the colors look more pastel with muted hues on my laptop. The yellow of the case and the similar color on the chart (first column on the right, second row) seemed to match up best on 400ISO on my laptop. I doubt they're the exact same color though.
Thanks for the comparison!

Oh I read on another forum that the 100 ISO setting is actually more like 64. Not sure what their source was or how they came to that conclusion.
 
Steaphany,

I would have to concur...it does not do bad...it just does not produce the colors like the lower levels...

Great study...

Tony C.
 
Hi All,

just do have a closer look HERE!

Foveons HIGH ISO results are not that bad as one might think. Unfortunately SIGMA's "In-Cam-Picture-Processing" does not do a lot to make the best from their sensor's output. We can do that ourselves! I did some research in the issue! :)

See you with nice HIGH ISOs

Klaus
 
Back
Top