Precision and Accuracy in LF Photography: How much is enough?

[reddesert]

As others have noted the need for accuracy and/or precision depends on what you are trying to accomplish. But in all cases, consistency will help you accomplish those ends. The degree of precision or accuracy that is needed or that is achievable is also set by different processes (for example, optics vs chemistry vs artistic needs) and critically, it also depends on what tools are available to make measurements.

For example, if you want to make sharp images on film, then you should be concerned about placement of the lens, film, and focusing device to fractions of a millimeter (and this number is set by optics, the wavelength of light, and the resolving power of film).

Say you want to control the lens to film distance to 0.1mm, and it's a 150mm lens, that means you need to measure to 1 part in 1500 precision. Fortunately, you have a measuring device built into the camera, the ground glass (or maybe a rangefinder), that enables you to measure this accurately and precisely. That's one reason that even if the temperature changes or wood swells or whatever, that you can still make images, as long as the GG back has the correct depth to match the film holders and the camera doesn't flop around. Trying to focus a camera with only a ruler and no focusing aid would be desperate.

On the other hand, when trying to get the exposure time or development time right, your limits are set by how the film density increases with exposure and development time - density vs exposure curves and so on - so that's governed by chemistry rather than optics. Measuring devices are also less accessible. There are people who have densitometers and measure their own HD curves and so on to set developing times and exposure indexes, but many people also use experience and the manufacturer's recommendations. Because chemistry is different from optics, you can get away with less precision in say shutter speeds or dev time than you can in GG focusing. Few amateurs try to control exposure or developing time to less than 1 part in 100, let alone 1 part in 1000. Probably the item in film processing that needs greatest precision is the temperature of color processing.

With either of these aspects of process, it helps to have consistency. If one keeps changing things it is hard to know what is going right or wrong.

[Drew Wiley]

Oh how snooty, Otto! One who does landscape photography can be sloppy; but an architectural photographer never is? What if someone does both, and even with the same equipment and same level of commitment? Heck, I considered architecture easy by comparison; things are more likely to stand still, there is nowhere near as much detail to juggle at the same time, images planes are less complicated, and you can control the lighting and placement of things in studio or interior setups. But outdoors, lightings ratios and sudden shifts can be severe, so one needs to be even more nitpicky about knowing exact shutter speeds, especially if chrome film is involved. But maybe you think we're just a bunch of postcard types taking pictures of cute chipmunks.

Of course, I don't think that is what you actually meant; but it's how your statement came across.

[Bill Burk]

@jp I like the precision/accuracy scale. The one with no precision and no accuracy should have fewer marks on the target though (because some will miss the entire dartboard).

I see I fall into the accuracy without precision boat. I like to understand the different factors and make sure my aim is true. Then I fire away with reckless abandon knowing I will hit the dartboard every time.

[otto.f]

But maybe you think we're just a bunch of postcard types taking pictures of cute chipmunks.

Of course, I don't think that is what you actually meant; but it's how your statement came across.

I reread my post but I cannot find the reason for that, sorry. I’m not a native English speaker, perhaps it’s that. I just told about my way of working, never had in mind to lecture anybody, neither do I see myself as a very experienced LF photographer

[Drew Bedo]

And sometimes dumb luck (or Karma?) comes into play.

Last shot in the twilight at the pond of a local park. Nice stuff going on but not that special thing. Without warning, the breeze shifts and my corner of the pond becomes mirror smooth. So instead of rigging down, I get out the last loaded film holder, meter, set and shoot. Then flip the holder to bracket and just as the shutter is tripped a duck swims into the compositing . . .click. The next day i had total hip replacement surgery. Whenever I can get back to my camera gear, I'll unload that batch and send it off to a lab (Denver Digital).

When it comes back from the lab I'll let you know how it turned out. Wish me luck.

[otto.f]

Nice story Drew, we’ll keep our fingers crossed for your hip recovery and your decisive moment

[John Layton]

At the end of the day, at least for "personal work," and in the realm of learning one's craft...I think consistency is the most important thing. Shutter speed accuracy makes no difference...so long as speeds are consistent. Film speed ratings make no difference...as long as a given film's sensitivity does not vary. A light meters ability to measure to a "standard" makes no difference...so long as that meter will, over time, give the same reading for a given amount of light. Its all about learning the materials. Take consistency out of the equation, and the pursuit becomes meaningless. This is why I have such a hard time with the concept of "student-grade" materials, which may lack consistency and thus the whole learning enterprise becomes moot.

[Alan Klein]

At the end of the day, at least for "personal work," and in the realm of learning one's craft...I think consistency is the most important thing. Shutter speed accuracy makes no difference...so long as speeds are consistent. Film speed ratings make no difference...as long as a given film's sensitivity does not vary. A light meters ability to measure to a "standard" makes no difference...so long as that meter will, over time, give the same reading for a given amount of light. Its all about learning the materials. Take consistency out of the equation, and the pursuit becomes meaningless. This is why I have such a hard time with the concept of "student-grade" materials, which may lack consistency and thus the whole learning enterprise becomes moot.

But the problem with large format equipment, especially old lenses, is that they are old and often not accurate or consistent. That makes life difficult. It often becomes a distraction and new, modern equipment with high accuracy and repeatability allow you to accomplish getting the picture easier. I just started LF about a year ago and find it very fiddly. It's often like a contest. I often wonder if it's worth my time.

[Bernice Loui]

Solution to the overly common wore out vintage or inconsistent shutter problem, implemented since the late 1980's.. Sinar shutter (Drew, will not agree) with lenses in barrel and done. Only exceptions are modern wide angle lenses. This solution resolved a long list of view camera lens issues and allows virtually any lens-optic to be used on sheet film. The advantages to this solution is not small or insignificant in many ways, yet often never considered by many. If not for having done this decades ago, the fondness for vintage lenses like Kodak Ektars and many, many, many more in barrel with nice round iris would have not happened. Modern lenses can be Sinar DB or DBM mount if needed and they historically have been low market value, yet very nice to use in many ways.

Culling out all the lenses in shutter recently as they have not been used in decades. Better for them to find a good new home with an image maker that will used them to create expressive images again.


Bernice

But the problem with large format equipment, especially old lenses, is that they are old and often not accurate or consistent. That makes life difficult. It often becomes a distraction and new, modern equipment with high accuracy and repeatability allow you to accomplish getting the picture easier. I just started LF about a year ago and find it very fiddly. It's often like a contest. I often wonder if it's worth my time.

[Drew Wiley]

Ha! Caught ya on that one, Bernice! I wanted you to ditch your Sinar shutter so I could obtain one for my own use!