Topic: technical (2 posts)

Not Usual

I don't usually write about photo equipment. But for the past couple of years I've been using something that is way cool and that you may not know about. Briefly, most of you know I worked with an 8 x 10 view camera for 25 years. I photographed using 2/14 (120mm) systems as well and occasionally shot with  4 x 5. I  switched to full time digital in about 2006 and work with a DSLR system full time now.

My dream when moving on from all that time working with 8 x 10 inch sheet film was to have a smaller camera capable of the same or close to the same levels of quality within my lifetime. Drum roll please: for all intents and purposes that dream is now a reality. I am able to make large prints of close to the same level of quality as prints made with an 8 x 10 inch view camera. Bang!  Digital capture has come a long way.

What a remarkable thing. But there are limitations to standard cameras like DSLR's  as well. Cameras such as these fix the relationship of the lens to the image plane in a parallel configuration. This can be very  limiting. No correcting for convergence, no Scheimpflug principle. Don't know what that is?

Here is Wikepdia's answer:

The Scheimpflug principle is a geometric rule that describes the orientation of the plane of focus of an optical system (such as a camera) when the lens plane is not parallel to the image plane. It is commonly applied to the use of camera movements on a view camera.  The principle is named after Austrian army Captain Theodor Scheimpflug, who used it in devising a systematic method and apparatus for correcting perspective distortion in aerial photographs.

You may need to be  sitting down here: by tilting the lens you can increase sharpness from foreground to background without stopping down the aperture to increase depth of field. Sharpness from close to far with the lens wide open? Yup. The pebbles in that gravel driveway sharp on out the horizon with my 50mm lens set at f2? Yup. I'm not lying. View cameras can do this and, if you've snuck a look at the picture of the lens below, you probably are thinking that it will allow this as well. Yup.

I ram referring to modern perspective control (PC) lenses, sometimes called tilt/shift lenses.

I use the Nikkor 24mm f3.5 PC lens. Wouldn't it be great to be able to make view camera adjustments with a small camera? Well, you can. The Nikkor lens shifts up and down, and, when rotated, swings side to side. The lens also allows you to look up or down but the  photograph you make looks as though you are parallel to the surface. That's good because then the edges of the building will stay parallel instead of converging. Want to shoot straight on through that window and not be reflected in the glass? PC lens. The PC lens also tilts, taking the lens out of being parallel with the camera's sensor. It can also swing if rotated. Wish you could shoot straight out from your toes to the horizon and hold it all sharp? PC lens. Imagine being able to hold things sharp from foreground to background without having to stop the lens down.

For this one taken at the Russian River in California I used an 8 x10 camera tilted for sharpness using the Schiempflug principle.

Hand holdable? Yes, but not easy. The lenses are manual focus and the adjustment knobs are small. I've done it but its easier and more precise from a tripod. What else do you need to know? Because it can tilt and shift quite far you can vignette the image and, as at times you are using the lens at the edge of its circle of covering power, the image can also get quite soft, or blurry. Normally, this is my sharpest lens, particularly used without tilts and shifts. Also, these are pricey lenses, in the range of $2000. Nikon makes them in three lengths, 24, 45 and 85 mm. Canon too. Canon also makes a 17mm. These lenses are used most often for architectural photography by pros. But that doesn't mean you can't do great things with them. Finally, what about using a PC lens for selective focus? Using one to make the picture blurry in places where you don't want your photograph sharp. To make only one small thing sharp. Easy with a PC lens. This is the primary principle behind the whole company called Lensbaby; selective focus. Last point, you could rent a PC lens to try it out.

Series of mine where I used this lens? Sconset, Nantucket and Baldwinville (under the pseudonym Marc S. Meyer). One more thing. Tired of always having the foreground in your pictures? Want more sky without pointing up? Did Marc (sic) use a PC lens to reduce the foreground in the Baldwinville pictures? Yup.

Topics: Scheimpflug,Commentary,technical

Permalink | Posted August 18, 2015

File Size Flexibility

In digital photography there is much discussion about file size. File size? What is that? This refers to the number of megapixels (MP) a given chip or sensor in a camera has to capture the light coming through the lens.

Generally, the number of megapixels has increased in size since early digital cameras. What was once regarded as excellent at 6 MP is now thought of as being small and what was regarded as impossible at 24 or 36 MP is now relatively commonplace.

On screen at 72 DPI (dots per inch), pretty much any camera makes files that look very good. That can include smartphones. It is when putting ink to paper to make a print that some of the smaller file size cameras and smartphones don't hold up.

Again, generally, the larger the file size, meaning the higher number of MPs a camera can record, the larger the prints it can make.

There are important and longer range considerations to keep in mind regarding what camera you use and what you can and can't do with the files shot with it.

In early digital days my first digital still lens reflex (DSLR) camera was a Nikon D70. I believe its sensor made 6 MP RAW files. This becomes larger when processed into an RGB file and ends up at about 34 MP. (BTW: RAW is not an acronym for anything and simply means that the file once shot isn't processed into anything in the camera. That's why it shooting RAW  is referred to sometimes as a "digital negative").

Small files sizes look fine on screen:

This photograph of my 8 x 10 camera in Wyoming shot in 2005 looks fine here on screen, but blow it up and take a look at its makeup were you to make a print 36 inches across and a crop looks like this:

Not so good.

So, what's my point? The only real reason for a 24 or 36 MP DSLR over something like a 10 or12 MP camera is print size. Simple enough.

Let's compare what that looks like:

Full file from the Nikon D800e (36MP):

and the cropped image:

Nothing is falling apart here because there is far more information contained in the file and therefore an enlargement holds the sharpness and detail far better. This is roughly equivalent to the difference in enlarging a 35mm negative to a big print size verses enlarging a 4 x 5 or 8 x  10 inch negative to the same size.

So, much is made of new cameras and their amazing capabilities but stick to making 4 x 6 inch prints and you could be working with a 10 year old digital camera and the quality would be fine and you could save your money.

For most people out there a camera shooting in RAW mode at 12-16 MP is about right and meets most needs. Anything with more MP is for those wanting to make larger prints at higher quality. 

All this is pretty straightforward and may sound like Digital Photography 101 to many of you but there is a more subtle and longer ranging issue to think about and that is: what do you want to do with the photographs you make now in the future? 

Since beginning to work with full frame sensors and cameras with 24 or 36 MP chips, I have had options available to me in terms of print size I didn't have before.

Another way to put this is that I cannot show any pictures I made with the 6 MP D70 Nikon larger than about 8 x 10 inches, and even that is a stretch. For someone who often makes 36 to 40 inch prints for exhibition, this simply eliminates that work from consideration. Knowing this back then, I wasn't very serious about what it could do and didn't dig in and make real work with it at all, thank goodness.

A final point:  I seem to be saying that working with a full frame sensor camera that shoots a RAW file in the 24-36 MP range makes good sense, and I believe it does. The downside is that everything gets bigger and slower too. This means larger and  more storage, bigger files and slower computer times. 

So be it. It seems a worthwhile trade off to me. 

Topics: Commentary,technical,Digital

Permalink | Posted February 6, 2014