### Scheimpflug - do I need it?

greenspun.com : LUSENET : Large format photography : One Thread

I am very new to large format, so please bear with me. I do know about Scheimpflug. I also understand, that once you have set lens and film plane at the angle desired, there is an infinite number of object planes compatible with it (in books often drawn like a wedge). Thus Scheimpflug does not garantee that the desired object plane is in focus and some additional rule seems needed (I believe called the "Hinge rule").

My question is this: What is Scheimpflug good for? My technique so far is to a) focus on the background, b) tilt the lens until the foreground is in focus (and repeat procedure several times to adjust for lens extension). Am I missing something?

-- Andreas Carl (andreas@physio.unr.edu), May 26, 2000

The Scheimpflug rule is only half the answer. As you point out, there are an infinite number of planes that satisfy the one rule. The other half of the answer is the Hinge Rule as stated by Dr. Merklinger on his page: fox.nstn.ca/~hmmerk.

Understanding these rules is not really necessary for good results. But a little knowledge about what is happening is nice to know when things don't always happen the way you think they should. The technique you describe is a good way to get the job done. I use the same sequence myself, but after reading about the Hinge Rule, I know about where to start. Don't worry about exact rules and measurements, this is art, not rocket science. Good luck!

-- Ray Dunn (raydunn@mcn.net), May 26, 2000.

I'm still searching for the value of "y"!

-- fred (featon@hiwaay.net), May 26, 2000.

I fully agree with Ray... on the Merklinger site, he has a short movie that shows the relationship between tilt angle, the hinge point (J) and back focus distance... I could write 5 pages and it would be very hard to understand... however, watching this movie, you will understand it in 10 seconds. The only additional peice of information you need after seeing the movie is knowing where to start your tilt angle.... its pretty simple... estimate how far below the lens J is, in feet(the distance below the lens, the plane of sharp focus passes through - you must estimate this, or calculate it) you will see it in the movie or on the same page... then do some simple math in your head, fl/j*5 = tilt angle. This simple formula will get you 95% accurate, then tweak the rest till the gg looks perfect.... best of luck.

-- Bill Glickman (bglick@pclv.com), May 27, 2000.

set up some wooden lettered blocks, like children (and LF photographers) play with endlessly, and build walls and towers. now, try several camera configurations to see how best to bring them into focus. once you have learned the fundamental movements, just think about it as distance and angles from subject, lens, and film plane.

in the opposite sense of a carnival mirror, or as in Kertesz's distortion essay, we can contort the light path to facilitate our focusing requirements. it is those initial movements that set you down the path, and should become very intuitive. stray off the path through guesswork, and you will find it very difficult to get back on track without taking Scheimpflug's name in vain.

-- daniel taylor (aviator@agalis.net), May 27, 2000.

Can someone post a URL to Merklinger site? The one posted doesn't work for me.

-- Chris Hawkins (peace@clover.net), May 27, 2000.

Andreas: Your question is something like asking "what is Newton's third law good for?". It is a statement of fact (barring quantum and relativistic effects!). Scheimpflug is a statement of fact... the lens plane, film plane, and plane of best focus always do intersect in a line. That said, your technique is fine. The quarterback doesn't need to "use" Newton's third law, he just throws the ball.

-- Glenn C. Kroeger (gkroeger@trinity.edu), May 27, 2000.

Thanks for all the responses! I found the Merklinger site. It's at http://fox.nstn.ca/~hmmerk/index.html

-- Andreas Carl (andreas@physio.unr.edu), May 27, 2000.

I have been using LF for a few years now, and I own copies of Dr. Merklinger's books and have visited his site. Having said the above, I believe it was time and money well spent. However I also believe that if I had started there, I would have made a very quick trip to the local Land Fill and disposed of all my photograhic equipment and still would have been to intimidated to even buy a disposable 35mm. The information is very useful and has application but I would advise you to simply set your camera up and look at the glass and experiment. I still find myself getting lost in the simple pleasure of looking at the glass and trying to focus on any object. I have used the blocks,a box of 1" ball bearings dumped on a table(try to get all of the reflections on all of the balls in focus, and my favorite is still Buildings endless Buildings(brick seem to be best for practicing corrections). And you don't need to make an exposure every time you set up the Beast. After a while you will be able to set up the starting point for focusing without even thinking about it. Then if you feel the need, read the books and you will find that your mind will be able to better relate to the information. Your technique is much the same as most of us use. It's just that some prefer not to admit to the tried and true, Trail and Error method.

-- R.(Mac) McDonald (rmacsteam@aol.com), June 09, 2000.

I see people all the time in the field who start out by setting up their cameras with levels so the back is verticle. And then they get lost when they have to use anything more than front tilt and swing. They get a receding plane or converging lines on something that is 20 feet off the ground and don't know how to incorporate back movements and front movements to get what they want on the ground glass. Why? Because they didn't learn what the formula was saying. Not how to solve the formula but what it was saying. You don't have to know the formula just the why of it. Get the View Camera article about what schiemflug said and the hinge rule and get out the camera and practice, practice, practice. The ground glass never lies. It is easy once you see what it is trying to tell you. You don't need any levels, palm pilots, formulas, or other gizmos. There's nothing mysterious and magic about it. All you need to do is look at where you want your focus to be and use the movements to bring those planes into focus. Very easy once you do it a few times. James

-- james (james_mickelson@hotmail.com), June 10, 2000.

Thank you to everyone who answered Andreas' question i went to the web site suggested and i now almost understand the sciempflug rule. I had to learn and write an essay on it for an assignment and could not find any websites that actually explained it and with 30 mins to go before my lecture I found this site, and I promise this will be the first place I look in future.

-- Becki Hosking (beckihosking@hotmail.com), November 27, 2001.