Monday, January 17, 2011

Flower Power - Painting With Light


Cold wet winter days can be a real drag especially if your interest is in photographing flowers. An alternative to shooting flowers outdoors is of course to photographing in the cozy surroundings of your living room.

Most people don't have access to a studio but this need not prevent you from taking beautiful studio type photographs on your living room table. This image was taken just that way in fact and whats even more fun is that it was lit with the light from a bare bulb table lamp using a technique called "light painting"!

You'll need a steady tripod for this exercise as you'll be using a fairly long shutter speed, fairly long can be anything from 1/2 sec to 3 minutes depending on the ISO and aperture and brightness of the light source you select. Set your camera to M for manual also focus the lens manually and turn off "auto focus" Try using ISO 100 and a aperture of f/4. Trial and error will help you find the right shutter speed depending on the tone of your flower but 1/2sec-1 minute might be about right  - open the shutter and begin to paint the light over the flower by moving the light around the image, you can give a little to the background or more to the left or right for a different effect, try to keep your hand out of the frame but if it sneaks in just momentarily it probably won't even appear in the photograph.
If your first attempt is too light then shorten your shutter speed by half and if its too dark try doubling the amount of time you paint with the light.

I used a dark cloth for my background with the photo here. The settings were ISO 100 f/6.3 shutter speed 1/2 second. I've even used an I-Phone to light my pictures but the exposure is likely to be about 3 minutes so you'll have
 to set your camera to "bulb" and as you open the shutter start counting 1-1000, 2-1000 etc,. or you can 
set your I-Phone timer and get a 2 for 1 deal! I simply converted to gray scale in Photoshop and added a curve adjustment to accentuate the contrast between the light and dark areas.

Saturday, January 15, 2011

Understanding USM (unsharp mask)


There are many factors that determine the quality of the final print, it's where the rubber hits the road and what can seem like a great image on a monitor can soon appear disappointing in print form. For many photographers the print is the last step, the grand reveal. Of those major criteria for a great print is the appearance of sharpness and a major consideration in the making of a digital photographic print is the sharpening stage or moreover the process by which to achieve it. Unsharp Mask (USM) filter in Adobe's Photoshop is an edge contrast  tool used to create the impression of sharpness in the image. The filter compares tonal changes in the image, then exaggerates the differences between them. This can lead to the appearance of a sharper, or in some cases where necessary a softer image.
Understanding the USM features
I'm often asked to explain the features of the USM tool and how each relates to the sharpening process,so here's an attempt to explain simply what they are and what they do.
Amount:how much of an increase in edge contrast should be applied.
Radius: how far in pixels on either side of a contrast change the sharpness will be applied.
Threshold: how much of a contrast change must be encountered before the filter is applied. 
An often overlooked aspect is that you do not have to apply USM to all three channels, many digital cameras suffer from noise in the blue channel of the color file, which can be exaggerated in sharpening. In Photoshop you can select one channel and sharpen it as required. You can choose to  sharpen selected areas of an image too.
There are no magic numbers for an “ideal” sharpening workflow. Factors such as the sharpness of the capture whether its via camera or a scanner, the resolution of the file, film grain, or digital noise; the paper you print on,i.e., matte fiber or glossy and the overall look you desire. Generally I start with a pixel radius of 0.3 pixels, then increase the amount until it looks correct to me.
When working on files from my medium format digital back which are very high resolution, I set the amount to 300, threshold to zero and radius to .3, If I were to do this with a Nikon or Canon DSLR file it would likely introduce really terrible halos. When scanning film try going up to 4 or 5 on the Threshold to avoid sharpening the film grain. There is no set rule; you need to experiment and discover the results that please you. Remember, over-sharpening  creates ugly halos around hard tonal edges.
When viewing images on screen for sharpening I set the sharpening preview window to 200% and then I view the final image on screen at 50% to make a final assessment before committing ink to paper. Again, these are personal preferences but try them and see if they work for you. Here's a little tip, after you sharpen your image use the Fade filter (under the Edit menu) through the Luminosity mode - Edit>Fade USM>Luminosity and back the slider off to about 70% to reduce possibility of emphasizing  color artifacts caused by the Bayer-pattern sensors.
Whether you use Photoshop or some other sharpening software, most sharpeners are essentially creating light and dark outlines around contrast changes, the trick is to create those outlines without being visible. If a dark or light outline becomes visible then the logical fix is to back off on the amount or radius.

An alternative sharpening technique within Photoshop:
Another variation on edge detection is to use the High Pass Overlay technique.
1. duplicate the image
2. Set Blending Mode to Overlay
3. run Filters/Other/High Pass on the just copied Layer. Start with a value of 2
4.vary the opacity of the Layer for effect you desire
5.erase parts of the new Layer where the effect is over done such as along high contrast edges, i.e., where sky meets mountains or perhaps erase the sharpening effect on the sky completely.
A final comment: focus your camera carefully to begin with, use a fast enough shutter speed to prevent camera shake. Digital"sharpening" is about creating an optical illusion, not about sharply focused photographs. The "Perfect Print" begins in the camera.

Wednesday, January 12, 2011

What lens should I buy?

The lens that comes packed with a DSLR camera is referred to as the "kit" lens. More advanced photographers will often buy their camera bodies and lenses separately, but almost all first-time buyers get their camera in a box that also contains the kit lens. 
Back in the film camera era, the lens that was supplied with your new SLR was a 50mm fixed focal length lens. In the 1990's it became fashionable to supply a zoom lens, usually 28-80mm or thereabouts. With today's entry and advanced amateur digital SLRs, the kit lens is generally an 18-55mm zoom, or somewhere in that region depending on the manufacturer of choice.

For most people who buy their first Digital Single Lens Reflex (DSLR) camera, the lens bundled with the camera — the "kit lens" — serves them just fine. As the novice photographer begins to explore their creativity, they realize there's a world of possibilities and the "kit lens" becomes somewhat limiting. That's where an SLR camera really shines because it allows one to take that kit lens off and put other lenses on. At this point, though, the questions come thick and fast and the choices can seem overwhelming!

The bargain 50mm:
Most camera brands have a 50mm fixed focal length lens available. Known as the "plastic fantastic"  Canon sells a 50mm f/1.8 new for $100, and the Nikon 50mm f/1.8 is $125. These are classic lens designs, perfected over years of design and technology advances, they offer excellent optical qualities despite the bargain price.
A 50mm lens is a great focal length for general photography and portraits — it's slightly telephoto on APSC sized sensor DSLR cameras so it's perspective is flattering for portraits, and it provides a working distance that is very comfortable for portraits. In other words, with a 50mm on your DSLR, you are working at a comfortable distance to your subject where you can fill the frame nicely if desired or back away a little for a half length body shot. The 50mm lens is also a wonderful general focal length for many other forms of photography with its slightly telephoto perspective try using it for landscapes, architecture and still life.
Because a 50mm f/1.8 provides a very wide aperture, it's excellent for low-light work and for experimenting with shallow depth of field. A bargain 50mm is light, cheap and as close to optically perfect as you are going to get. A must have lens in your kit bag in my opinion!
The Macro Lens:
Many photographers are interested in exploring macro photography. What type of lenses are needed for macro work?  Macro lenses tend to fall in a range of 50mm-100mm focal lengths. A macro lens is a lens designed to let us get a tiny subject at full size in our shot. In other words, even if we are photographing a small insect or a detail in a rock, we can get close enough that we can fill the frame with that object. Anything can be photographed with a macro lens as they focus from infinity all the way down to a couple of inches.
Macro lenses can be pricey especially if you buy a camera brand to match your DSLR. One can save a lot of money and still get excellent quality by purchasing off brand lenses such as Tamron or Tokina to name only two but both these manufacturers and particularly Tamron produces a stellar performer with their classic 90mm f/2.8. This lens design has been around for decades and you just can't go wrong, it's fast, light and very versatile. The Tamron 90mm f/2.8 is currently listing new for about $450 and used examples are readily available on Ebay.
Wide Angle Lens:
Personally I'm not much of a fan of zoom lenses of any focal length, they are optically inferior to fixed focal length lenses and unless your budget is around a $1000 then I would not even consider buying an additional lens for your kit bag that included a wide angle perspective. By wide angle I'm referring to lenses 28mm and below - 24mm, 20mm, 18mm are some examples.
Sigma offers a bargain lens with their 28mm f/1.8 which currently sells new online for around $350. I don't own this particular lens but I have made exhibition prints to 24" x 36" for a client and the images produced were quite beautiful. When printing an image this is where the rubber really hits the road because all the MTF charts and lens data mean nothing compared to a real life print hung on your wall! This lens does have one downside: it's a very big and heavy. There are much smaller and lighter 28mm lenses out there — but the Sigma is about a stop and a half faster with its maximum aperture f/1.8 allowing for some very low light photographs to be taken especially where tripods might be impractical. If you are wondering what I use, it is an old Nikon manual focus 18mm f/4 rectilinear circa 1970's which I absolutely love for its high contrast qualities and very light weight.
In conclusion:
There are a lot of choices out there, a bit like your espresso bar, lots of different flavours.  Before buying any lens, use the Web and read reviews of how that lens works on your specific model of camera. You'll find that every lens has its positive and negative features, and that's definitely true on bargain lenses. So do your home work and have fun. The used market offers lots of possibilities and its usually the case that you can purchase a lens on Ebay, use it for a while and if you don't like it, sell there again for close to or even more than you paid for it. Just be sure to purchase from a reputable source with good history and someone who will stand behind their products for sale.

Disclaimer: 
My writings are my own personal opinions, I have no affiliation to any manufacturer or brand and my opinions are just those which have come from my experience of using various forms of equipment over 30 years.