Andy Westlake tests Sigma’s unconventional SA-mount mirrorless camera, the sd Quattro
Sigma sd Quattro review: Performance
In use, the sd Quattro is a reasonably responsive camera, and the slow processing and write times that plagued the SD1 Merrill are gone. It’s not going to challenge similarly priced enthusiast DSLRs for speed, especially when used in its resource-hungry SFD mode, but it won’t leave you waiting much, either.
Its main flaw is an unusually long viewfinder blackout time, particularly if you have quick preview enabled for checking each image after shooting. However, this is handy to keep turned on, as it helps you to spot when the sd Quattro’s white balance or metering have been errant.
This isn’t to suggest that either is wildly unreliable – indeed, most times the sd Quattro gives nicely judged, attractive images. But it’s less consistent than some if its peers and can be prone to over-neutralising atmospheric lighting such as warm evening sunlight.
It will occasionally overexpose too, clipping highlights in an unusually inelegant fashion. Attempting to recover any lost highlight detail in SPP reveals that there’s very little room to manoeuvre, as ugly hue shifts appear. But you can’t underexpose too much, as then you’ll see noise when pulling up shadow detail.
When you do get things spot on, then at ISO 100 the Foveon sensor delivers remarkable results, with stunning detail and subtle colour gradation. Unfortunately, you don’t have to raise the sensitivity very much for all this to go wrong, and by ISO 800 blotchy green and purple shadow noise becomes a real problem. Above this the JPEG resolution takes a nosedive, with the camera apparently processing at the 4.9MP resolution of the two lower sensor layers, then upscaling to 19.6MP. There’s little in the way of shadow detail, too.