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Archive 2012 · Sigma DP2 Merrill: Have any of you tried it?
  
 
Herb1911
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p.31 #1 · p.31 #1 · Sigma DP2 Merrill: Have any of you tried it?


mpmendenhall wrote:
It would be pretty obviously awful if color information was gone at -2 stops; that's more like mid-tones than deep shadows. If I have time this evening, I'll try some color test shots at deeper underexposure (unless someone beats me to it). My (not yet carefully confirmed) feeling is that the color threshold kicks in at about -4+ stops at ISO100 (similar to shooting at ISO1600+, where image color gets pretty marginal).


mpmendenhall,
My shadows already start at - 2 stops
But I would like to see your test at what under exposure level color starts completely missing.
It is always interesting to find out what Sigma is doing backstage to show us the Foveon at it's best.

Herb




Nov 05, 2012 at 08:11 PM
Tariq Gibran
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p.31 #2 · p.31 #2 · Sigma DP2 Merrill: Have any of you tried it?


Herb1911 wrote:
@Tariq Gibran,

The following is my personal finding sofar and maybe not the absolute truth.
SPP just builds in a tone curve when processing RAW depending on the color mode choice. Whatever combination you choose you cannot get back to a linear curve. Even with fill light and or contrast adjustments. Probably to prevent seeing more noise than Sigma likes us to see.
You can of course apply a new curve on a processed tif but at the risk of seeing unwanted artifacts.
One of the really strong points of the new Nikon's is there ability to push the shadows very far without introducing
...Show more

Thanks Herb. I tend to agree with your findings based on what I'm seeing.

By the way, if you find "absolute truth", let me know!



Nov 05, 2012 at 08:12 PM
mpmendenhall
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p.31 #3 · p.31 #3 · Sigma DP2 Merrill: Have any of you tried it?


sector99 wrote:
SIGMA is catching a lift from their new cameras and one can see them offering a CSC mirrorless body product. If they are smart SIGMA will first offer an M-Mount, then an APS-C monochrome sensor (FOVEON without filters) in order to threaten the Leica MONOCHROM body.


An M-mount body won't be happening with the current generation of sensor technology. Current Foveon sensors are prone to severe color shifts due to varying light angles from lenses; the majority of interesting M-mount lenses would produce fairly unusable results. Only SLR designs (where some limitations on light angles are enforced by the requirement to clear the mirror) or specially designed extra-telecentric lenses (e.g. DP1M, DP2M lenses, which are different from "typical" rangefinder mid/wide designs) can produce acceptable results. One can hope that further technology developments (improved microlens arrays like Leica has developed? fancy shaped silicon like the recently discussed Sony patent?) will eventually make this possible, but Sigma can't just slap their current sensors in an M-mount body with useful results.

Also, what's a "FOVEON without filters"? In the Foveon design, the sensor silicon is the only filter. A "Foveon without filters" (i.e. without silicon) would be the Emperor's New Clothes of sensors, capable of producing the finest ZEROCHROM images for devoted fans of minimalism



Nov 05, 2012 at 08:16 PM
Johnny B Goode
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p.31 #4 · p.31 #4 · Sigma DP2 Merrill: Have any of you tried it?


I am so very tempted to sell my 50mm 1.4, the images posted are amazing.



Nov 05, 2012 at 08:31 PM
carstenw
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p.31 #5 · p.31 #5 · Sigma DP2 Merrill: Have any of you tried it?


sector99 wrote:
If they are smart SIGMA will first offer an M-Mount, then an APS-C monochrome sensor (FOVEON without filters) in order to threaten the Leica MONOCHROM body.


If Sigma is smart, they will go after a much bigger market than that. The M market is tiny compared to most other segments.



Nov 05, 2012 at 09:27 PM
mpmendenhall
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p.31 #6 · p.31 #6 · Sigma DP2 Merrill: Have any of you tried it?


OK, here's an exposure push test series to check for shadow desaturation.
Taken under (icky) compact fluorescent lighting, with quick "custom" gray card WB. SPP "neutral" color settings, NR defaults (middle setting). All at ISO 100, varying shutter speed in 1-stop increments, then pushing results in post (first 2 stops in SPP, rest in Aperture) to keep lower-left white square at fairly constant luminance.

No attempt was made, beyond the gray card WB, to get colors "correct" in this, which might have been futile under these lighting conditions because color accuracy was pretty awful to start with.

-0 stops (nominal "correct" exposure by camera, a bit lower than I would have manually chosen):






-1 stops, pushed +1.24






-2 stops, pushed +2.27






-3 stops, pushed +3.27






-4 stops, pushed +4.6






-5 stops, pushed +6.4






-6 stops, pushed +8.0






Color saturation never completely goes away, but it drops pretty steeply at -4+ stops under. There is definitely also a strong nonlinear "S-curve" tonal adjustment being applied (as Tariq has noticed), based on the increasingly large amounts I needed to push the files (compared to the shutter speed, especially at -4 and beyond) to keep constant exposure; the bottom row of gray patches also shows a steeper fall to black at lower exposures.



Nov 05, 2012 at 09:36 PM
mpmendenhall
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p.31 #7 · p.31 #7 · Sigma DP2 Merrill: Have any of you tried it?


For comparison, here are ISO1600, 3200, and 6400 versions for the exposure -4, -5, -6 shots (increased in-camera ISO instead of post-processed pushed ISO100). These do better than the pushed versions for retaining color, and don't need additional pushing beyond nominal to correct for SPP's exposure curve. The DP2M is definitely not an "ISO-less" camera like the D800/Sony sensors.


















Nov 05, 2012 at 09:45 PM
mpmendenhall
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p.31 #8 · p.31 #8 · Sigma DP2 Merrill: Have any of you tried it?


Another issue in the exposure push series, increasingly visible in the -4, -5, and -6 shots, is how the RAW developer is segmenting the image into different blobby regions, with sharply defined borders, to guess what the color is in each. I suspect that (and this would require further testing) color reproduction at low exposure falls off even more quickly for areas with high spatial frequency color changes (as opposed to the uniform test chart patches, where the algorithm can try to average the color response over a larger region).


Nov 05, 2012 at 09:54 PM
Herb1911
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p.31 #9 · p.31 #9 · Sigma DP2 Merrill: Have any of you tried it?


mpmendenhall,
Thank you for the interesting and hard work.
Your findings confirm the day to day shooting sofar with the DP2M.
How much this is an image quality issue very specific for this camera i am not sure. We have to keep in mind that the new Nikons with Sony sensors are state of the art at this time regarding this subject.
Sigma burries the nasty artifacts in the toe of the tone curve, not intended to get extracted per raw converter.A valid decision but hopefully things can improve in future Foveon developements.

Herb



Nov 05, 2012 at 10:13 PM
Tariq Gibran
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p.31 #10 · p.31 #10 · Sigma DP2 Merrill: Have any of you tried it?


Nice test!


Nov 05, 2012 at 10:18 PM
 

Search in Used Dept. 



mpmendenhall
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p.31 #11 · p.31 #11 · Sigma DP2 Merrill: Have any of you tried it?


Here is the ISO100 image re-processed in SPP with "Fluorescent" white balance, followed by color correction (46C+30M) to the lower-left patch, instead of the "custom" gray-card WB used in the above sequence. Still "neutral" color style. It's not perfect, but a whole lot better than the badly under-saturated "custom" WB version. Lesson learned: because color reproduction is a much more complicated process for DP2M images than just getting the gray point correct, "custom" WB with a gray card under "adverse" lighting (probably anything off the regular outdoor/daylight continuum) is likely to be unhelpful. The built-in "closest" camera WB setting, even if the gray point needs significant adjustment, provides a better starting point.








Nov 05, 2012 at 10:29 PM
carstenw
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p.31 #12 · p.31 #12 · Sigma DP2 Merrill: Have any of you tried it?


But the reds and oranges look brown...


Nov 05, 2012 at 10:31 PM
mpmendenhall
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p.31 #13 · p.31 #13 · Sigma DP2 Merrill: Have any of you tried it?


carstenw wrote:
But the reds and oranges look brown...


Like I said, it's definitely not perfect --- far from it --- but a better starting place than the really horrible color reproduction produced from the gray card "custom" white balance. From here, one has a chance of tweaking colors to get a bit closer to reality.

Here's the version with some custom tweaking in Aperture; it's still not perfect, but would probably be close enough for shots of most items besides a color chart (where other people can tell exactly what it should be):







Nov 05, 2012 at 10:36 PM
deadhumpy
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p.31 #14 · p.31 #14 · Sigma DP2 Merrill: Have any of you tried it?


Nothing special about the photo, although I think the sigma did a nice job on the colors for what it was, just a snap shot in our local safeway. Anyone pay over $6 for a tomato before?







Nov 06, 2012 at 01:52 AM
mpmendenhall
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p.31 #15 · p.31 #15 · Sigma DP2 Merrill: Have any of you tried it?


And now, for everyone's daily dose of "WTF, SPP?," here's a 100% crop from an ISO 1600 file set to Monochrome in SPP.

If you look closely enough, the "monochrome" pixels are in color (red and green noise patterns). Yes, it's like that in the original TIFF16 output by SPP, not just this JPG crop. WTF, SPP?








Nov 06, 2012 at 04:47 AM
sector99
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p.31 #16 · p.31 #16 · Sigma DP2 Merrill: Have any of you tried it?


It's time for a visit to flickriver "dp2 merrill". Select "Interesting" in the search window.

Spend some time there and discover the truth about SIGMA DP2M color for yourself. No color "Checkers" needed to "Explain" what you can see with your own eyes. No imaginary color in monochrome images either.

Just 12,399 images taken by real photographers displayed against a black flickr background.

You want bokeh? You want spatial resolution? Your want vibrant color? You want it in your coat pocket?

You want to match FF DSLRs?

Some experts say you can do all of that––with a little determination.

I'm not shilling for SIGMA here––just changing the subject to reality in images.



Nov 06, 2012 at 05:01 AM
rscheffler
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p.31 #17 · p.31 #17 · Sigma DP2 Merrill: Have any of you tried it?


Tariq Gibran wrote:
Now crops showing 100% details from the DP1M on the left as compared to reduced crops from the Nikon D800E + 28 1.8G on the right:
http://www.gibranstudio.com/dp1mc.jpg
http://www.gibranstudio.com/dp1mb.jpg
http://www.gibranstudio.com/dp1ma.jpg

The Sigma DP1M images appear as if a curve has been applied which had the effect of increasing mid tone contrast at the expense of loosing shadow detail (think S-curve). The effect can look really good overall but I think I would prefer having control over creating that look rather than it being the default.


Not just an S curve.. it looks like the same result as duplicating the image as a layer, changing it to Overlay, Soft Light or Hard Light and applying High Pass filtration to that layer (or to some degree, the Clarity slider in LR).



Nov 06, 2012 at 05:10 AM
glacierpete
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p.31 #18 · p.31 #18 · Sigma DP2 Merrill: Have any of you tried it?


sector99 wrote:
What Mr. Gilbran's examples (Just ABOVE) clearly reveal to me is (1) better spatial resolution as evidenced in blades of grass against the light grey path (2) better contrast AND spatial resolution on the fire hydrant and (3) a more realistic appearance in shadow detail for the SIGMA DP Merrill images vs. the NIKON D800E images.

As for the color checker/Lightroom examples above I'm far less sanguine over any color channel weaknesses since these examples aren't from camera RAW results. the comment that SIGMA is attempting to "Hide noise" is pejorative in nature and as such should be ignored on its
...Show more

Sony seems to be well aware of the shortcomings of Bayer sensors. They have a patent on a foveon alike technology. Outdated Bayer technology is a cash cow, and as long as customers are crying for more mp instead of image quality, there is little incentive to invest in new production facilities and technologies.
http://www.sonyalpharumors.com/next-sony-foveon-alike-patent/



Nov 06, 2012 at 05:35 AM
Herb1911
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p.31 #19 · p.31 #19 · Sigma DP2 Merrill: Have any of you tried it?


I have been experimenting with and Expodisc and a UV filter.

I found that the DP2M responds quite a lot to UV radiation from the sky.

A good UV filter in front of the lens works very positive on this camera reducing noise and color blotches.

Here a screen dump with left UV filter, right no filter.

A basic landscape with 50% sky photographed through an Expodisc, one stop over exposed.
ISO 100 SPP Neutral no noise reduction. In Lightroom maximum boost of saturation and vibrance.
Increased contrast and reduced exposure with one stop. This only to show the effect most clearly.

Sometimes the perceived sharpness seems improved with the UV filter, but the filter can cause also some slight dulling effect on the contrast. In pushed ISO 100 files you can see improvements in shadow noise and banding.

Herb






200 % right edge frame, left with UV filter, right no filter







top average landscape, bottom 100% sky - left with UV filter, right without UV filter







200% crop ISO 100 1 stop shadow push, left with UV filter, right no filter







as above quartet, without boosting color and contrast, just plain SPP neutral




Nov 06, 2012 at 10:53 AM
Tariq Gibran
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p.31 #20 · p.31 #20 · Sigma DP2 Merrill: Have any of you tried it?


rscheffler wrote:
Not just an S curve.. it looks like the same result as duplicating the image as a layer, changing it to Overlay, Soft Light or Hard Light and applying High Pass filtration to that layer (or to some degree, the Clarity slider in LR).


Yeah, there are lot's of ways to get there. I guess I had in mind a localized curve in the dark tones like this:







Nov 06, 2012 at 01:19 PM
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