Review:http://www.martinzimelka.com/homepage/Blog/Blog.html

NAVIGATION:

The detail in the DP2m’s images is a real treat, however, there are some aspects of image quality that don’t quite meet the levels we’ve come to expect from other cameras. Chroma noise in shadows is relatively high, and SPP cleverly desaturates these shadow details to make it less obvious. Luminance noise levels are also higher than one would expect from a 15mp APS sized sensor. Luminance noise levels aren’t too bad and give images a film-grain look, but shooting colour is best done at lower ISO values. Shooting above ISO 400, chroma noise starts becoming a little blotchy. Shooting in B&W, and processing the images in SPP’s monochrome mode, is far better suited for higher ISO shooting. In addition, noise levels improve significantly when SPP’s B&W colour channel picker is put into the blue part of the colour disk.


So whats the motivation for shooting with the DP2m? Well, the Dp2m is a small compact camera capable of exceptional image quality. The Merrill cameras have a unique look to their images, boasting a much higher spatial resolution to that of other 15mp cameras.


While the pros and cons of this camera can be weighed up very differently by each person, the decision to use the DP2m is likely going to be a very informed and deliberate choice. What each person wants and expects from a camera is quite subjective, and there are many photographers for whom the DP Merrill cameras are not the right choice of camera.


I really like that this camera allows me to maintain the disciplines I have for shooting film. I’m incentivised to make each image count, since the battery only last for 70 shots and the camera needs 12 seconds before I can review it. Images require good exposure for good results, and appropriately, poorly exposed images return poor images.  Files are large, fitting about 230 images on a 16GB card, which is about the maximum I’de like to have with me per outing. I don’t carry more than 10 or 20 rolls of 120 film per outing, so why can’t I do the same with digital.  The DP2m doesn’t really allow for much haphazard, fix-it-later-in-post style of photography, forcing the user to be a little bit more in touch with what he’s photographing and how to photograph it.

Image Quality

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The DP2m RAW files don’t have a huge dynamic range, and while it’s plenty sufficient for most situations, there are some situations that may require pushing shadows or pulling back highlights. There is only so much headroom in the 3XF RAW file, and pushing the shadows too far will likely introduce too much noise for your liking. There is a neat trick one can apply, allowing for cleaner shadow details, and thus allowing shadows to be pushed a little further than usual. Nikon’s multiple exposure menu has this rather neat and largely unknown method built in, but since this isn’t a Nikon SLR, one needs to replicate it in Photoshop. It’s called a median filter, which blends multiple layers in Photoshop according to a set equation, averaging the pixel values of each pixel address and thus averaging out random noise.


All one needs to do is, take 2, 4, 6 or however many images in quick succession, keeping the camera perfectly stationary. The DP2m lacks a cable release or remote socket, which is remarkably stupid, so take care when squeezing off the shots. With a cable release option out the window, this would’ve been a great moment for setting up an interval timer sequence, but Sigma failed us again with a 15sec minimum time limit between shots. So, having shot your image sequence, you’ll need to process each file with exactly the same settings in SPP, and save them preferably as 16 bit TIFF files. Load these files as layers into a stack using Photoshop, and now change the opacity of the layers following this equation...


Layer Opacity % = 100 x 1 / (number of layers below + 1)


Since a lot of noise in an image is random, this method smooths out any information that isn’t true picture data. For noise that is not random, for instance fixed pattern noise, the method will not do much at reducing it. In fact, the perceptive decrease in random noise could make fixed pattern noise more obvious. However, using the median filter stacking system, you’ll achieve far better results when pushing the shadow detail of your image.


Mouse over to see an actual pixels crop

While the DP2m does relatively poorly recovering shadow detail, the prospects for highlight recovery is somewhat better. It’s not a good idea to rely on decent recovery, but I’ve been surprised at times, especially for B&W images. The image-slider on the right compares an overexposed scene (left) with the same image but with a -2 stop adjustment in SPP (right). A grossly overexposed image as this one will not recover well as a colour image, but the Neutralise/Restore slider in the Highlight Correction tab can contribute a lot to the look of the final result.


Below is another comparison, this time a colour image. The fairly monochromatic nature of the mask makes recovery relatively easy.

Full image:

actual pixels crop:

The scene on the right was shot and edited purely to demonstrate the effects of the median filter using Sigma DP2m files. I used 7 images for this demonstration, usually 4 is plenty.


In SPP, I batch assigned the Noise Reduction settings to be at the minimum setting for Chroma, Luminance and Banding noise. I then processed all files equally with sufficient fill-light to emphasise shadow noise, as seen in the image on the right. Mouse-over to see the original scene.


After loading the files into layers in Photoshop, I changed the opacity of each layer following the median filter equation. For those that have Photoshop Extended versions, you can select all layers and convert them into a smart object (Layer/Smart Objects/ Convert to Smart Object). After this, apply the Median filter in the smart filter stack mode (Layer/Smart Objects/Stack Mode/Median)


The effect of this median filter can be seen in the image-slider on the right. The image on the left is the output of a single file, and the image on the right is the output of the median filter applied across 7 images.


While the changes might not seem too dramatic, there are instances where this method can be incredibly powerful. I admit it’s not as practical with the Sigma DP2m as it is with my Nikon D700, but nevertheless it does make a difference.