Previous page Next page

Real world RAW advantages

Shooting RAW on the SD1 brings all the usual advantages - you can fine-tune processing individually for each shot, adjusting such things as white balance, brightness, and colour tone. It's therefore the format of choice if you're after the best possible image quality from your camera (and let's face it, there's little point in buying the SD1 if you're not). Perhaps the SD1's greatest strength in RAW is its exposure latitude, with RAW files containing considerably more highlight data than JPEGs.

Highlight recovery - studio scene

The SD1 behaves distinctly differently to most other cameras with regards to its ability to recover highlights from RAW that are blown in the camera's JPEGs. With conventional Bayer-sensor cameras we normally expect to see about a stop of luminance information in the highlights, but with ever-decreasing colour inaccuracy (as individual colour channels clip sequentially). The SD1 behaves somewhat-similarly at ISO 100, but switch to 200 or higher and it surpasses this dramatically, offering an extra stop of full-colour information in its RAW files that's simply not used in the JPEGs. This means that, at ISO200 and higher, the highlight range available in RAW at least matches the best APS-C DSLRs.

In the examples below we show how this looks using our standard studio scene. We've shot in JPEG+RAW firstly with correct exposure, then 1 and 2 stops overexposed. We've then pulled-back the RAW files to compensate, using the Exposure slider in Sigma Photo Pro. We're showing side-by-side crops from the Q60 colour checker chart in the upper right of the scene, comparing the overexposed JPEG and the recovered RAWs at ISO 100 and 200. Note that in the 'correctly-exposed' version of these shots, the lightest tones are approximately 1/2 stop from clipping in JPEG.

ISO 100, RAW + SPP
ISO 200, RAW + SPP
Correct exposure
1 stop overexposed +1 EV / -1 EV in SPP +1 EV / -1 EV in SPP
2 stops overexposed +2 EV / -2 EV in SPP +2 EV / -2 EV in SPP

In this example, at ISO 100 overexposure by a stop results in clipping of the lightest tones in the chart on the camera's JPEGs, but this data can be recovered accurately from the RAW file. However 2 stops overexposure and recovery is a complete no-go; some luminance information can be retrieved, but colour information is lost across much of the chart. In contrast, at ISO 200 and 2 stops overexposure, the results are essentially identical to overexposing ISO 100 by one stop. This means that you'll get maximum latitude for overexposure at ISO 200; we'd estimate you can expect to recover at least 1.3 stops above the JPEG clipping point with full colour accuracy. This in turn means that in bright, contrasty conditions we'd recommend using ISO 200 by default.

Real-world highlight recovery

Here we're showing a couple of examples of how the SD1's RAW highlight recovery can benefit your real-world shooting.

This quick close-up was shot using centre-point AF. The SD1's evaluative metering is very closely-linked to the active AF point, which has resulted in overexposure. Large regions of the JPEG are clipped to pure white, and on many cameras this image would be a complete write-off. The playback clipping warning confirms just how much of the image is overexposed in the JPEG file. However the image was shot at ISO400, so there should be plenty of highlight data in the RAW file. Let's see what it looks like...
A quick click on SPP's Auto setting sets negative exposure compensation of 1.7 stops, which recovers almost everything that's clipped in the JPEGs. The red channel is probably not 100% accurate in the brightest regions, but overall this is an impressive recovery. A little tweaking of the sliders results in this more-balanced final conversion. Here exposure compensation is set to -1.3 and the X3 Fill light to +0.3, which (as its name suggests) fills in the shadows pleasantly.
In this second example (again at ISO 400), the sky is clipped almost to pure white. With most cameras, if your JPEG looks like this then the RAW file will have little more to work with. A few moments playing with SPP's image-control sliders, however, allows recovery of both the blue sky and the subtle late-afternoon light on the clouds.

This is all very impressive stuff on the face of it, but it has to be kept in context. The SD1's huge RAW highlight recovery ability stems as much from the relatively-limited JPEG highlight range as anything else - the RAW files don't necessarily contain very much more highlight data than those from competing SLRs. We'd actually prefer to see that data used in the camera's JPEG processing, to give better highlight rendition (and therefore more usable images out-of-camera). This would also offer a more-accurate indication of what's in the RAW file when playing back your images.

RAW files for download

Here we provide RAW files, both from the review and the sample shots we take, to allow you to apply your own workflow techniques and see whether your experiences match ours.

Previous page Next page
I own it
I want it
I had it
Discuss in the forums


Total comments: 9

To update a three and a half year old review a little, as a recent convert to the Foveon sensor in this Sigma (albeit in the DP2 Merrill iteration) I can testify that the latest Sigma Raw processing software, Photopro 6.3, which is used for the SD1 Merrill as well ithe DP2, does not leave much to be desired, at least to a relative newcomer to Raw processing. And this running on Windows 7 on an ancient Core 2 Duo at 2.66Ghz with 4 Gb of memory. There may be frustrations for those who wish to devote more time to arcane debate than taking shots, but on the whole Photpro6.3 hits the spot. Hats off to Sigma....


Is this the 24-70 ART lens that you are using ? I have the 28-80 HF and 18-50DC's but the Chromatic Aberration is shocking with these and I cannot achieve a constant colour, without discoloration around the edges. I was thinking of buying an adapter and looking for a better lens, possibly a Nikon one.


Use a full frame lens like the 24-70 F2.8 EX DG HSM. You will get fantastic results. Use it properly - on a tripod at 100 ISO and F8. Have good light. Shoot raw. Convert to 48bit tiff. Edit with the appropriate skill. If the results don't blow you away, your doing something wrong.


I photograph textiles for a living and I have a love hate relationship with this camera. Some of the results are stunning, then at other times it is infuriating. The fact that I cannot Wifi the camera drives me mad,a friend is trying to solder up a device, so I can attach a ribbon cable to compact flash type 1 holder, then have a type 2 WIFI one mounted externally. I am envious of my colleague that works with a Nikon and uses her iPad to control and tether her camera, with an instant review of the post and final image .


If you shoot at 400ISO or less, use the best lenses, shoot raw and use the latest version of the much improved Sigma raw conversion software, you will be able to upsize your clean artifact free files to around 6700 pixels across giving you an equivilant resolution of a 30MP Bayer sensor. I do this all the time and the results are fantastic. Using a full frame lens on this sensor gives you images that are sharp to the corners and almost distortion free. The 24-70mm F2.8 HSM on this sensor enables image quality way beyond anything I ever shot on a 5D2 or 5D3 with L lenses.. When you get to know the tool and develop skill to use it well, the results will blow you away. Most people want it easier than that. You reap what you sew!

1 upvote

I purchased an SD1 for my business of photographing textiles in a studio situation and I feel totally deflated. The actual image quality is excellent, but the tethering capabilities are pathetic. I expected to be able to click from my PC to launch a shot, then instantly see what I had taken, before moving on to the next item, which sadly is not the case. Their software application known as Sigma Capture Pro should be reported to the trading standards council, as there is nothing 'Pro' about it as it is just a glorified remote shutter release program. Furthermore in order to have access to your images on a PC, you need to go into the menu function on the camera and disable the 'remote capture program' then select mass storage to view your images. Going through this process with every shot, may be good for you cardiovascular system, but for someone who relies on seamless throughput to make a living, this camera is junk.


Tethering capabilities? lol. You are more interested in showing off in front of clients than achieving great results. Re-align your priorities. You do realize that 90% of the time the images are used at 400 pixels wide on a web site - do you? you don't need to check each shot at 100% mag on a full size screen before you know you got it. Give us a break with your grandstanding.


I was looking at the photo comparison today, comparing the SD1 against the new Canon 5 D Mk III, the Nikon D800E, and the Pentax 645 D . . . at ISO 800 . . . and I just can not believe my eyes. Take a look at this:

The SD1 never ceases to amaze me.

Scott Greiff

Why won't the comparisons load?

Total comments: 9