Scheimpflug Principle and the Hinge Rule

[Thomas W Earle]

I read "Focusing the View Camera" but find it hard to actually use out in the fi eld, especially in judging distances and where the plane of sharp focus resides. Basically, I take mostly landscape pictures and I've been only using the view camera for about 6 months. Yesterday I was trying to get a scene focused from c lose to far and was never successful. I was using a Fuji 450C and was trying to get a wheat field in front of my lens into focus while holding infinity at focu s too. Basically, the scene was two rows of wind turbines in a field of wheat i n gently sloping terrain. The closest wind turbine was a little less than a 1/4 mile away (i.e., not quite at infinity for this lens but close) and the rest st reched into the distance. The wind turbines are about 90 feet tall. I'm sure a s you move into longer focal lengths it gets tougher to get everything into focu s, but I would still think you could get a little more things into focus than wi th a fixed lens. What am I doing wrong? Should I use my Nikor 300M lense inste ad? I could go as low as 150mm , but the wind turbines would look pretty darn s mall, and they would loose their perspective focus. Any suggestions would be gr eatly appreciated.

Thanks in advance,

...Wade...

[Jorge Gasteazoro]

Heck Thomas I read this book too and found it imposible to figure out all those angles etc. Get yourself the Rodenstock DOF and Schiempflug calculator and meke your life a lot easier! is only about 20 bucks and so simple to use it does not require a degree in mathematics to decipher.

[Thomas W Earle]

Jorge,

Matter of fact, I do have the Rodenstock calculater, but had difficulty deciphering it too. It appears the calculator is geared more towards monorail type cameras, whereas my camera is a field camera. First, in Step 1 it talks about the winkle angle. I assume with landscape photography it will usually be 0 degrees. Is this correct? Step 2 is somewhat confusing too. I know I'm interested in tilting and it talks about the vertical distance between point S1 and S2 on the screen. Do you just measure this vertical distance from the ground glass? I wouldn't think their relative position would change much or is the focusing at this point just to pin point their location on screen? I assume Step 3 just deals with the horizontal distance between the focus point of S1 and S2. Finally, in Step 4, this angle will usually be from the ground to the middle of the tallest object, right? Any other comments or suggestions on using this calculator with a field camera would be greatly appreciated.

Thanks,

...Wade...

[QT Luong]

With a 450, for most scenes, it is normal not to be able to get everything in focus. You'll need to stop down significantly. On the LF home page, there is a method that I recommend for finding the optimal f-stop, which does not require calculations, although it is based on sound optical principles.

[Jorge Gasteazoro]

Thomas, I have both a 4x5 TK45 and a Gandolfi 8x10. The Gandolfi is a somehwat "traditional" field camera, with a few exceptions and I am able to use the calculator easily with it. I will run with you on the step, I think you have the same problem I had when I first got it, whoever made the instruction booklet assumed you were Pythagoras..lol. anyhow...here goes: (I will put numbers here so you can follow) Step 1.- Ok, you know how some times when you are using the field camera you tilt the ENTIRE camera down because you dont have enough movements? well this is the angle they are talking about, how much did you tilt the camera? now, I know this is hard to figure out, my solution was to buy and inclination vial (Horseman inclination vial II, sold at B&H for about $49). I put it on top of either standard and I automatically get an angle, this is the alfa angle. If you are tilting the camera more than 40 degrees then maybe you should rethink the composition. For example put this to the 15 degree mark.

Step 2.- YES! you measure the distance between the closest and farthest objects ON THE GORUND GLASS (caps for emphasis, not yelling). for that the calculator has a ruler in cm. then you move the dial until the arrow aligns with the number you get. (remember the number is in milimiters so 11 milimiters would corrspond to 1.1 cm from the ruler on top of the dial). rotate the black dial until the red arrow aligns with the 29mm mark.

Step 3.- Focus on the closets object, mark the position. Focus on the farthest object you want in focus and mark the position of the standard, measure the distance the standard traveled to focus on both subjects. Place the WHITE dial until the red arrow is pointing to the number 3 this is in CENTIMETERS units. ( I know this people really mess you up going from millimeters to cenetimeters back and forth).



Step 4.- try to guess what the plane angle between your closest object and the top of the farthest is. just for grins lets say you have an angle of 10 degrees, you read the little line coming from the red arrow and you see an inclination of 5.5 degrees for your FRONT standard.

As you can see from the numbers I used for example it really does not make much of a difference the beta angle, since the tilt will go from 5 to 5.75 degrees, most cameras can't measure fractions of degrees, I know my linhof TK can't, so a tilt of 5.5 degrees would most likely give you a plane of focus that would have everything in focus from parallel to the ground to about 45 degrees. I hope this helped you, I know it sounds very complicated when written down, but in the field it is a snap. Another thing, place some objects on the floor, lets say a sheet of paper close to you camera and a tall object farther away....like a coat hanger etc. and practice setting the calculator and see what results you get, I practiced this way before I took it out on the field, at least this way I was in an AC place not sweating my a** off...lol....

[Brian Ellis]

've been told that the Hinge Rule and other stuff in Merklinger's book is designed for working in the studio where precise measurements can be made and where you're not worried about the light changing, the subject moving, etc. As you've discovered, it's pretty well impossible to use in the field, even if you can comprehend it (which I couldn't). For me, the best system for focusing a view camera is that described by Tuan elsewhere on this page, which is based in large part on two articles that appeared in Photo Techniques magazine several years ago. Basically, you put a milimeter ruler on your camera, focus on the near, note the reading on the ruler, focus on the far, note the reading on the ruler, then move the lens to a point that is mid way between the two readings. You then determine your aperture from published tables based on the distance in milimeters between the points of near and far focus (the greater the distance, the smaller the aperture). If you want a citation to the original magazine articles, let me know and I'll send it to you but Tuan's article is very good and easy to understand so you probably don't need the articles.

[Jorge Gasteazoro]

Brian, I think to what you are reffering to is Depth of Field, which is an entirely different cat to skin.....

[paul owen]

Most LF users have at some time had the same frustrations as you when coming to grips with focus, how much tilt to use and depth of field, etc. Although Merklingers (spelling??)book is probably correct, it is difficult for us mere mortals to decipher, (well I found it difficult). Forget the book and take advice from posters on this forum, they make everything much simpler...books don't talk back, these guys (and girls) do! I found that the biggest problem I had was that I wanted to use ALL the movements!! In practice, movements are often very subtle, especially tilt. My advice...listen to what the forum has to say, check out the previous postings on the subject, and take your camera outside and play with it!! Don't worry about exposing film, just get used to seeing the effect of each movement on the GG. There's too much to take in when starting out in LF, so forget the added pressure of metering and exposing film and concentrate on that big screen! Regards Paul

[Bill Glickman]

Thomas, I give you a lot of credit for your due dillignece on this subject. Merklinger is brilliant, he better understands view camera geometry than anyone alive today, the only problem is his ability to communicate his knowledge in a book! That is too bad, because he truly is a modern day pioneer in view camera movements. His addendum that comes in the back of the book is more useful than the book itself. I will summarize many points of his book that are not clearly defined. I also think you should review Tuan's articles also, as I find his methods very useful also.

1. Just because a camera has movements does not mean everything can be in focus! Sometimes tilt is just not practical! There is view camera math, which Merklinger is famous for and then there is practical application in the field, which he does not offer much on, except a bit in the addnedum. There is several problems you must be aware of using lens tilt. First, tilting the lens eats up the image circle, therefore the amount you can tilt is limited to the size of the image circle of your lens - not what a calculation tells you to use. Second, tilting the lens alters the angle of the plane of sharp focus (PSF). In addition, compared to non tilt cameras, it reduces the amount of DOF you have at the near point, provides the same DOF at the point of exact focus and provides addtional DOF at the far point - assuming the same f stop in both examples. The reason is because of the cone shaped DOF that surrounds the PSF vs. the paralell DOF on non tilt cameras.

2. Merklingers web site, linked on this home page, offers a great visual video showing the relationship between the PSF and the tilt angle. This quick time video is invaluable for mastering the concept of lens tilt. The book just can not demonstrate this like the video can. Seeing is understanding. I suggest you watch this, then everything will fall into place using Merklingers simple rules.

To focus the camera, it requires 3 distinct pieces of data, tilt angle, focus point and f stop. Here is how I accomplish each in the field using Merklingers methods.. (this is after I determine I can not get the scene into focus with out lens tilt. And of course this is no gaurantee the scene will come into focus using tilt, only certain types of scenes are well suited for lens tilt, the video will make this obvious to anyone)

1. Tilt Angle. After deciding tilt is necessary, vs. box camera focussing, Merklinger can run you through some serious high level math to get to the tilt angle, however, after you wade through his charts and formulas, I have found his simple formula of Tilt angle = fl/(J*5) is all that is required. This simple formula will get you the proper tilt angle within 95% of the long hand version. And as one poster noted above, getting tilt angles to 1/10th of a degree is useless since no camera can tilt to that accuracy anyway. All that you need to visualize is how far below the lens the PSF will intersect, i.e. (J, in ft.) Then do the math. So 10 ft J with a 150 ft lens is about a 3 deg tilt.

2. Focus point. Focus the camera until PSF, intersects the middle of the tallest subject. (tallest item needs to be judged based on the its distance from the camera and its height, when in doubt, pick the closer item to the camera)

3. f stop. For this, it helps here to have a Hyperfocal chart for your lenses which includes your desired cc you are trying to maintain. To figure out what f stop will give you the added DOF above and below the plane of sharp focus, simply measure out to the hyperfocal distance (at your selected f stop) and the DOF will be J ft above and J ft below the plane of sharp focus. If you want to know the DOF at a different distance from the camera, say 1/2 the Hyperfocal distance, then divide J by 1/2 also and apply it above and below the PSF.

In some cases, it pays to have a laser rangefinder to know the distances of objects in your scene. Of course you can also attempt to set the f stop by merely stoping down and looking into the gg, but this does not take all things into consideration such as desired cc.

So this summarizes Merklingers methods for proper use of lens tilt. With very little math, which you can do in your head and the use of a Hyperfocal chart, (which should be carried anyway for non-tilt focussing) your done! It's not perfect, but in less than a minute you can be damn close to perfection.

This simplified procedure works in most all situations, however it does not work when doing close up work or when using extreme lens tilt, i.e. greater than 15 deg. (most lenses would be in the low resolution of the image circle, or will have exhausted the image circle at this point.) If you have a large image circle lens and exceed 15 deg tilt, then you need to use the effective fl... But this method above fits 95% of landscape scenes I encounter.

Hope this helps!

[james mickelson]

I'm not sure so don't beat me up here but isn't the C a tele lens? If that is the case, part of the problem with the tilt or swing is that the nodal point of the lens is somewhere out in front of the front element of the lens. I had a hell of a time with some tilt and swing combos when I borrowed a tele lens once. The focussing on these types of lenses will be somewhat different than a normal lens whose focussing is figured with the nodal point halfway between the front and rear lens element. The other point here is that a lot of new comers to LF try and use "wayyyy" to much movement. Movements are subtle for the most part. If you look at the scene and read the books you will see how easy it really is to use movements. The logic is impecable if not the instructions. Take the camera outside and play with it. It will become a lot easier that way. James