Photograph Works

My diary in photographs

  • Nikon D200 and D40 image processing compared

    I used a Nikon 105mm f2 DC lens, which is a very sharp lens, for both shots.

    I shot both shots at ISO 200, in aperture priority mode at f4. The D200 exposed the image at one half a second, and the D40 exposed the image at eight tenths of a second.

    Before taking these shots I shot a scene out of the window, but decided not to use it because the details were so small that it was difficult to tell what was happening. But what was clear from those shots and from these shown here, is that the D40 shoots warmer.

    That is, it reads the color temperature of the subject as being warmer. Therefore the D200 shots tend more towards the blue end of the spectrum, and look bluer, and the D40 shots look more yellow.

    This is easily changed in the RAW processor but it worth knowing how the cameras behave ‘out of the box’.

    I shot in RAW and converted both shots together in Adobe Camera Raw 4.1.

    Once converted to PSDs, I made the crops by using the rectangular marqee tool set to 475×475 pixels, and in each case copied the crop to a new file and then saved using save for web and devices.

    The areas covered by the crops are different, one from the other, because the crops subtend a different area of the total frame. This is because the D200 has 10 megapixels, whereas the D40 has 6 megapixels.

    D200 crop
    D200 crop

    D40 crop
    D40 crop

    I’ve written in other posts, that the 18-55mm kit lens on the D40 seems to produce images that are as sharp at 24mm as the 12-24mm Nikon lens produces on the D200. So now we have the same lens used on both cameras, and the message that shines out to me is:

  • Get out and shoot with the D40 because it is not inferior in image processing to the D200, and
  • Use the 18-55mm kit lens on the D40 because it is sharp.

    • There are other reasons to get the D200 and I will post about these, but for a lightweight camera that is far superior to any compact camera, and which does not cost a fortune, the Nikon D40 is a winner.

  • How to clean a sticking Scroll Ball on an Apple Mighty Mouse.

    The Mighty Mouse is great. Going back to a mouse that does not have a tracking ball is like going back to steam-powered computers.

    But from time to time, the little ball sticks. It will either track up but not down, or down but not up, or… you get the idea.

    So I googled for answers and most people suggest that you turn the mouse upside down, hold down the ball with one finger and blow air into the space that is created around the ball, to dislodge any crud.

    And it has worked for me. I just blow into the space – no canned air, no compressed air, just a few quick sharp puffs of breath into the little space between the Scroll Ball and the hole it is in, and it clears it.

    But last night it didn’t work – maybe I had a little grease on my finger that got transferred to the Scroll Ball; maybe the crud had accumulated. Whatever the reason, blowing didn’t clear it.

    So I sprayed a drop of computer-screen cleaner onto a tissue, using only enough to be sure it was just ever so slightly damp but not wet, and rolled that over the ball. Magic – it’s like new.

    Ze Mighty Mouse

    Mighty Mouse

  • Truck in Manhattan

    Nikon D40 1/60 f7.1 ISO800

    truck

  • Displacement maps in photoshop

    The image in the thumbnail is a crop from an image that was prduced using displacement maps in photoshop.

    Click on the image for a larger view. The original image I have posted is 900 pixels wide (it’s still a small file though), so it won’t fit on this page except as a thumbnail, so click to see it bigger.

    yellowdisplaced

    I learned about displacement maps as a method of blending a type layer so that it appears to follow the contours of a background layer – so, for example, one could make a slogan appear to follow the folds of a T-shirt.

    But displacement maps can be used with any two images.

    The method
    You are working with two images. One is the image you are working on to create an arty image (I’ll call the image you are working on, Fred for convenience) and the other is the image you are going to use as the displacement map.

    Both images should be PSDs and 8 bit.

    The displacement map image can be any image in 8bit PSD on your drive, but I have found that using another version of the original image you are working with, can work well. So open Fred, increase the brightness and contrast; desaturate it, play about with the hues or desaturate it, and save it with some convenient name – maybe James?

    James doesn’t have to be open while you use this technique.

    Open Fred and go to Filter > distort > displace

    A box appears and asks you for values. You can put positive or negative values in the boxes, such as -30 in the top box and 21 in the lower box. It is up to you. I used to use small values of 5 or so, but I tend to use bigger values now. A lot depends on the image. Images with a lot of small detail (leaves on a tree for example) might suit one set of values, whereas a face might suit a different set).

    Click OK and you are asked to choose a displacement image. Choose James.

    That’s it – just watch the result appear.

    You can repeat the process. You can use the same or different values, or you can use a different displacement map image.

    And you can of course intersperse each repeat using other filters such as the artistic, sketch or liquify filters.

    Important
    If you like the result, don’t just save it or you will have overwritten Fred. Save it with a different name (Arthur, perhaps?).

  • How faithful are digital images?

    The processor in a digital camera can reveal or change the appearance of the information coming into the camera and we may notice it or not.

    The processor may alter the distribution of darker and lighter areas, taking out some of the subtleties. And we may see this alteration as making the image look artifical or unnatural.

    If it is a good camera it may show all these subtleties of tone, and do so in a way that film camera technology struggled to do.

    Lighting
    And using a flashlight and a mirror it is very easy to appreciate what is going on. Standing in front of a mirror in a darkened room and playing the beam from a flashlight on your face, we can notice how very small changes in the angle at which the light hits the face can make it appear narrower or broader, and can make features appear more or less pronounced.

    Every woman who makes herself knows how lighting affects the appearance of things, and of course studio portrait photographers use lighting to build a ‘light picture’ that best suits the subject. Lighting for film and television is an art form of building the preferred image with light.

    Altering information
    But the image processors in some cameras do more than just block up tones. They actually change the details of the subject I recall, some years ago, seeing crops at 100% of images from a digital SLR, where the camera had produced an image that did not reflect the subject.

    The processing engine in the camera had ‘moved’ darker and lighter areas around in the small details, and effectively altered the subject. An eyebrow appeared turned up at the edge, when it did not do so in the person being photographed.

    Digital technology has come a long way in the past few years in producing images that are both more film-ic and natural looking, and which accurately reflect the subject.

    Which is not to say that it is only the current crop of cameras that can deal with subtlety in tonal distibution. This is a crop from a studio shot taken several years ago with a Nikon D70 , which under good lighting, could produce good tonal subtlety.

    O

    What is good lighting?
    There is no doubt that current cameras can handle poor lighting conditions better than earlier models, whether it is bright and contrasty light or low light with deep shadows. But ‘handling’ poor light and using the best light are not the same thing and do not give equal results.

    The essence of studio lighting is that it controls the brightness range, and the photographer makes sure the range from the lightest to the darkest areas is within the capability of the camera’s processor.

    That restricted tonal range applies to daylight shots as well, which is why light but overcast days are better for photography than harsh sunlight.

    Lighting is described as specular or diffuse.

    Lighting from a small light source is specular and it casts a harsh shadow. The sun may be big but it is far away and it casts harsh shadows.

    Overcast days means the lighting is bounced of the clouds and diffused over the sky.

    With diffuse lighting the range from the brightest to the darkest areas is small. In full, bright sun, where there are harsh shadows and burned-out highlights, the range may be too great for the camera, and importantly, even if it is not, the tones have to be compressed, making for a less pleasant image.

    Many nature photographers put their gear in the cupboard throughout the summer season. Most shoot early in the morning or late in the afternoon to avoid the harsh unflattering overhead sun.

    Portrait photographers shooting outdoors use reflectors, overhead diffusers, and fill-flash to even up the lighting and reduce the overall contrast range.

    Overhead diffusers may seem an impossibility, bearing in mind how big the sky is, but take a look at some of the products from California Sunbounce.