Keep in mind your lens has only one focal point that exists as a plane parallel to the sensor (or film).  Depth of field is the distance in front of and behind the single point of focus where our eyes don’t notice a change in focus.  It’s technically defined as the circle of confusion.  Think of a point that is perfectly focused by your lens.  As you move the point of focus back and forth the original point will start looking blurred or out of focus (confused, as it were).  The depth of field is simply the bounds between which a change in focus doesn’t make the point look blurred.  Depth of field is a function of lens construction and aperture size, which is why sharper lenses with wide depths of field are usually more expensive.

Anyway, here’s an image I made using the second method – many images stitched together.  One issue with this technique is it’s almost impossible to do out in the natural world – nothing sits still for long enough!

ISO 100, 1/250 sec., f/8

This was made from 11  individual images, each one focused on a different part of the flower.  I started with the deepest part of the bloom and worked my way out to the edges of the petals.  In Photoshop there is a command that will auto-align the set of images (to make sure everything lines up and there are no ghost lines in the final image) and then auto-merge all the images together.  I guess the command was designed to look for “in focus” areas because that’s what gets selected from each image to make up the final image.

It’s almost unrealistically in focus.  Our eyes don’t see it like this unless in a photograph so initially it looks odd but our brains quickly adapt.  Cameras don’t see it this way, either.  The macro lens I used to make this, at the distance I was from the bloom, has a depth of field measured in millimeters, even with the aperture fully closed down to f/22.  A single image focused on the stamens (those yellow fluffy balls) would show the edges of the petals and back of the blossom as blurred.

Sometimes a picture is worth more than we can imagine when it shows us something we can’t normally see.

How big do you want to display your image?

It’s one of the first questions you need to think about.  If all you’ll ever do is show your images at full size on a computer monitor or TV screen or print no bigger than 8×10″, just about any camera out there will deliver the image size and quality you need.  6, 8, 10, 12, etc. megapixels – don’t worry about it, you’ll have enough to meet your needs.

Sure, you have to consider all those other choices available in your decision (lens, options, physical size, ease of use, etc.) but few of those will affect the answer you give to the first question.

And if you’re part of the crowd that wants to print bigger than 8×10″?  Well, how much bigger?  11×14, 16×24, 20×30, 30×45, size of your wall – where do you see your limit?  This important because more information in the image means you can print bigger and keep the quality you desire.

For example, my choice of digital camera is the Olympus system.  The sensor Olympus uses is smaller than a traditional 35mm film negative (which is called full frame or full format) and the image size is 10-12 megapixels.  This works very well up to slightly larger than 8×10; larger than that and my software has to “create” pixels from the existing ones to fill in the area created when the image is enlarged.  Various types of software do this differently and some are better than others.  The ones I’ve used enable me to print up to 30×40″ and get a print that looks good from a typical viewing distance of 6-8 feet.

As I am a resolution junkie (also known as a pixel peeper), this is not adequate.  I want good quality at that size from 1-2 feet (yes, I know people don’t stick their nose up to a large print but work with me – I’m a resolution junkie).  So I’m experimenting with film and scanning to create image files with more information.  The bigger the image you start with, the less quality you lose when it is enlarged.

Some data might help.  The Olympus sensor is 17.3mm x 13mm (or 0.68 x 0.51 inch) and mine delivers around 10,000,000 pixels.  My medium format film negative is 60mm x 60mm (2.3 x 2.3 inch) and my large format negative is 4 x 5 inches.  The image area of the medium format negative is 16 times the size and the large format is 57 times the size of the digital sensor.

Here are image examples of the same scene I photographed recently – no adjustments have been made other than converting the digital image to B&W using Lightroom’s standard settings.

Digital Image

Medium Format Image

Large Format Image

Here they all look pretty much alike.  If I enlarge each by 3 times their existing size and take 1″ crops out of each I get this:

Digital Image, 27 Inch Print Size

Medium Format Image, 25 Inch Print Size

Large Format Image, 44 Inch Print Size

Again, not that much difference.  But what if I want to print each the size of the largest (44 inches)?

Digital Image, 44 Inch Print Size

Medium Format Image, 44 Inch Print Size

Large Format Image, 44 Inch Print Size

Now the differences are starting to show up.  The digital and medium format images are less sharp than the large format image (some sharpening will bring out more details but the difference among the three will be unaffected).

So, the final size of the print determines how much information you need in your image to retain the quality you expect.  Most people rarely print so large they need a piece of film 4×5 inches in size but if you expect to print from your digital camera at sizes more than 2-3 times the size of the native image (the size of the image right out of the camera at normal print resolutions) then you need to consider the size of sensor you purchase and the number of pixels it will deliver to your software.

There are other issues to consider (size of pixels, shape of pixels, etc.) but all that is secondary to the sensor size when it comes to determining how big you can print with good quality.

So, size does matter, after a fashion.  Print 4×6″ or 8×10″ to share with friends or family, or show off your images on a computer or TV and you can pick your camera based on other features.  Starting planning some wall art, though, and you need to put in a little more research on the type of camera you buy.

Or, you can just invest in a large format camera and join the rest of us under the black cloth!

And it has performed as well as I could expect even once I learned how to use it well and probably push it to the limits of its capabilities.  Still, sometimes I wonder (as many photographers do), “wouldn’t I be better off with __________?”

Fortunately I found one remedy to that question – old tech film.  I shoot using 4×5 sheet film, scan to whatever size I want to print and go from there.  I’m still learning how to use it effectively, and yes it is slow and thoughtful, but for most of my work that fits my approach and actually makes me a better photographer.

How does it assuage my doubt about better resolution?  Well, here’s an example of a recent outing.  I was testing Kodak’s TMax 100 B&W print film for contrast on a very low contrast day.

4x5" sheet negative, Kodak TMax 100, 210mm, 1/4 sec., f/32, Yellow #8 filter

It’s a fairly narrow tonal range image but in keeping with the overcast day.  Good details in the shadows under the distant trees and some detail in the clouds.  The dark band down the right side is apparently a development issue I need to talk with my lab about.

There’s nothing spectacular about this image – just a test shot across a lake near the house.  You can see how the depth of field extends from the closest shrub all the way to the distant trees and the sharpness across the image is very good.  I do like the various tones in the image, from the trees to the prairie grass to the water – they give some definition to the topography and help define near vs. far features even though the lighting is very flat.

Oh, and the resolution?  Did you notice our new fire hall in the picture?  It’s right here:

I don’t know how far away that building is from where I was set up but I’m guessing about a mile.  This was a quick processing of the scanned image so I’m sure I can get a little more sharpness out of it easily.  In the uncompressed image (the original I made this one from for the blog) you can count the number of panes in each of the building’s windows and easily make out that the car is a Volkswagen Beetle.

I think I know where to turn for resolution higher than my not-a-full-frame-DSLR camera.

http://www.wired.com/rawfile/2012/01/famous-photogs-pose-with-their-most-iconic-images/?pid=1615&viewall=true

After playing around with some flowers I started experimenting on some glass objects that have internal elements – paperweights and such.  I wanted to see if I could illuminate the interior elements without getting glare off the outside of the glass, always a challenge with curved glass objects.  We practiced this in photo school but I never really felt I understood how to achieve it accurately.  And I wasn’t sure I could do it with the lighting equipment I have on hand.  Still, the flowers didn’t seem to be working for me and I knew the glass would be dramatic if done right.

I started with something pretty basic – clear glass around an interior design.  To eliminate the glare I found all I needed was a narrow slit of light off the flash, which I got by blocking the flash with a piece of black foamboard.

My first lesson from this is make sure the glass surface is perfect – little scratches or dings will show up as the light shines from inside out.  I can take most of these out in Photoshop but it’s better to start with clean materials.

This is direct side lighting – the heart is lying on a piece of black velvet and the flash is right at tabletop level with the black foamboard blocking all but a 1/2″ slit pointing at the heart.

I really liked the look of this.  The next piece sits up more vertical so I wanted to get the light coming from the bottom instead of the side.  Using a large round bowl that is tall enough to put my flash into and point upward I put a piece of black foamboard I’d cut a hole in on top and put the subject over the hole.  I hung another piece of black foamboard up to serve as a backdrop since I would be shooting sideways instead of downward.  All I wanted to show in the final image was the glass piece so I set my aperture where all the black background would have little or no detail.

I have no idea how glassblowers get these little elements inside the glass but they really work out well when lit up.  In addition to the flash under the subject I placed another flash to the right and turned it down to a low power just to give some definition to the edges of the larger fish.  It spilled over a little onto the backdrop (that brighter area up and to the left of the subject) but I found that helped give some dimension to the composition.

The up-from-below lighting was so dramatic I decided to photograph a subject directly from above, looking right down into the light.  I have a glass paperweight that is almost full of internal elements so I put it over the hole in the foamboard and set my camera directly above.  For this I turned the flash in the bowl up almost to 100% in order to get the brightness I wanted in the paperweight.

Not quite the Eye of Sauron but pretty haunting.  Looks like a red whirlpool or an image from one of those scopes they put down your arteries.

Well, with an image like this you can’t pass up some Photoshop opportunities.  So, a la Warhol, I made this.

Even though the dramatic flower photography didn’t turn out they way I wanted I’ve at least learned a little more about photographing glass subjects.  Light and glass always go together well!

http://photobotos.com/2012/01/17/great-sand-dunes-national-park-mel-mann-guest-photographer/

If you have an image you’d like more people than your regular group of friends to see, send it to Charlie and Tom for consideration.  And check their site often to see some wonderful images.

Empty following the harvest, corn bins stand shoulder to shoulder reflecting on their purpose while gazing out across a cattle-less fly-over plain.

ISO 100, 1/25 sec., f/11, 33mm

Surprise, surprise – winter finally showed up in eastern Nebraska.  And since we don’t do mild weather around here the 30-40 MPH wind roaring from the north to carry winter was no surprise.

We’ve had so little precipitation in the past couple of months there is little to hold down the soil, sand and other detritus left by the Missouri River flood so those pounding bursts of wind were picking all that up and lofting it into the air.  No grand landscapes today – too much haze in the atmosphere for distant images.

Instead I wandered down to one of Omaha’s favorite photo spots near the pedestrian bridge that crosses the Missouri, not because the bridge would be acting up (it’s shape and engineering make it very solid even in the face of today’s weather) but because I remembered there’s an unusual installation down there.  It’s a “garden” of long steel rods sunk into the ground and topped with clear plastic cans.  They are spaced apart enough to move freely, even in a high wind, without interfering with each other’s movement.  The effect is a wave visible both horizontally and vertically.  I knew the pieces would be highly active today and wondered what thay would look like against the solid bridge.

The sky was very overcast but while I was there a few breaks gave me a little texture in the clouds and a nice highlight near the horizon.  I’m hand holding this, which is not a problem with the image stabilization in my camera, but I was worried that 1/25 sec would not be slow enough to show the movement of the rods.  With the gusts thundering down the river that turned out to be no problem.  I got just the amount of blur I wanted, juxtaposed nicely against the taut wires of the bridge and the solidity of the pillars.  The curves of the bridge and railing, along with the line of the sidewalk and river, are just benefits to the composition, helping to both frame and break up the linearity of the lines from rods and cables.  A little adjustment in NIK Silver Efex Pro 2 and I have the sense of wind blowing across a cold landscape.

Unless of course you can find them in a situation where they can’t escape your attention.

ISO 100, 1/200 sec., f/6.3, 169mm

While driving around yesterday looking for B&W opportunities I caught this shape up in a tree out of the corner of my eye.  Being just outside the suburbs I instantly thought it might be a raccoon or other wild animal so I quickly turned around and headed back.  Well, it’s a wild animal all right, but not one typically found in a zoo.  Right below this intrepid climber is another cat who probably was the cause of this high perch.  While I stood there trying to get a good pose they were talking to each other but I doubt the conversation was about me.  The expression here seemed to be saying to me, “don’t just stand there irritating me, do something to get me down!”  As a big believer in letting problems work their way out naturally, I drove off and let this one deal with it.  Who knows – might still be up there today….

The many varieties of shapes and sizes of dogs have been removed from their wolf heritage by human action and as a result we don’t usually remember is how closely related domestic cats are to their ancestors in the wild.  There are actually only two  subfamilies of felids, the biological family of cats:  Pantherinae (lions, tigers, leopards, jaguars) and Felinae (cougars, cheetahs, lynxes, ocelots and domestic cats).  Their behaviors are all very similar as are their hunting and eating habits.  I had a chance to work on a research project catching mountain lions and tagging them, and discovered they have the same retractable claws, sharp canine teeth, smooth fur and purring that my house cat has.

Keep in mind the next time you are tempted to poke that napping tabby – there is just one biological step between them and their tiger cousins and you wouldn’t go around poking a tiger, would you?