PDA

View Full Version : Tilting camera and hinge question

jonathan_lipkin
11-Aug-2010, 07:55
Hello all --

Another newbie question on lens tilt. I have figured out how to raise the camera about six feet in the air (http://www.largeformatphotography.info/forum/showthread.php?t=65362). If I keep the camera bed level, using the Merklinger hinge rule the angle should be 5 degrees (angle = 5*focal length/J). If the camera is 6 feet, then J=6 and 5*6/6=5. All is good. And yes, I realize I need to focus a bit above the ground so I have depth of field above and below the plane of sharp focus.

But what happens if I tilt the camera down to encompass more of the foreground? Let's say for example that I tilt the camera down 5 degrees. Now the back and lens board are tilted at the same angle and so are parallel, and the plane of sharp focus is also parallel. If I tilt the back to vertical? This is the same as simply tilting the lens, no? Or maybe I should just use fall for the lens??

I'm getting myself terribly confused.

-jl

Jim Noel
11-Aug-2010, 08:21
It is time to stop reading and go out and photograph. Only through such experience will you understand when and how to use movements. The "hinge" rule makes good reading, and I am sure I use it at times, but never consciously.

Richard Wasserman
11-Aug-2010, 08:25
I can't directly answer your question except to say that I personally don't worry about the math of LF photography. I simply look at the ground glass and see what's happening as I make adjustments. For me it's much easier, quicker, and I don't have to break my brain. The ground glass doesn't lie. The other thing that really is the key is to practice, practice, practice. Just like getting to Carnegie Hall....

Joanna Carter
11-Aug-2010, 10:18
…Just like getting to Carnegie Hall....
You mean they're getting music out LF cameras now? :p ;) :D

Richard Wasserman
11-Aug-2010, 10:29
You mean they're getting music out LF cameras now? :p ;) :D

Well, they do look a bit like accordions....

rdenney
11-Aug-2010, 14:32
But what happens if I tilt the camera down to encompass more of the foreground? Let's say for example that I tilt the camera down 5 degrees. Now the back and lens board are tilted at the same angle and so are parallel, and the plane of sharp focus is also parallel. If I tilt the back to vertical? This is the same as simply tilting the lens, no? Or maybe I should just use fall for the lens??

Remember that the film plane, the lens board plane, and the focus plane will all intersect. If you tilt the film plane down a bit (by tilting down the camera rail), then you move back the point where it intersects the ground. Thus, you have to tilt the lens a bit more to reach that spot, though tilting the whole camera probably kept you pretty close.

You can also raise the rear or lower the lens standard to get more foreground. But tilting the film plane changes the perspective, so though both achieve the objective of getting more foreground into the view, they will still look a bit different.

The others are correct. This is much easier to deal with when using the camera than when using a calculator, and the equations don't matter if the image on the ground glass isn't sharp where you want it to be. Knowing the principles helps you know which direction to go, but you'll still make fine adjustments based on what you see on the ground glass with a loupe.

Rick "whose pictures always seem to require a bit of both tilt and swing, which complicates things" Denney

Kirk Gittings
11-Aug-2010, 14:37
I can't directly answer your question except to say that I personally don't worry about the math of LF photography. I simply look at the ground glass and see what's happening as I make adjustments. For me it's much easier, quicker, and I don't have to break my brain. The ground glass doesn't lie. The other thing that really is the key is to practice, practice, practice. Just like getting to Carnegie Hall....

Words of wisdom from a fellow KISS member!

Greg Miller
11-Aug-2010, 15:24
If you want to avoid any line convergence, then use front fall or rear rise (which would also be the same as pointing the camera down, and tilting the back and lens back to perpendicular to the ground).

If you want to introduce line convergence, the tilt the camera down and be sure both back and lens are not perpendicular to the ground.

Kevin Crisp
11-Aug-2010, 15:33
1. Kirk is right. It is a view camera. Use the ground glass.

2. A little camera movement goes a long way. You will find the amount of front tilt, for example, needed to get the foreground sharp is generally not very much. The ground glass tells you when you have the right amount. (I'm not sure what you mean by focusing above the ground in your post.) I think the camera ads with cameras twisted around this way and that into non-photographic positions give new users the wrong idea about how little movement it takes to get the job done.

3. Things still not looking perfect on the ground glass? Stop down. Even at f:32 or even 45 (on 4X5) you can make a plenty sharp print and that depth of field can come in handy. Stopping down a stop after you think everything looks fine on the ground glass can save you many times. Use a loupe.

4. Kirk is right again -- practice. Set it up in the yard. How would I do this or that? Try it and soon it will be second nature to use camera movements like rise, tilt, fall, and swing. (New LF people seem to get in trouble combining movements, often when not necessary. Just because they are all there, you don't have to use them.) Much easier to puzzle it out at your leisure and have it become intuitive for you in the field that to try getting it down when you're actually trying to take a picture on a trip. (Or even worse, when people are waiting around for you to make a photo on a trip.)

There are lots and lots of books that explain camera movements. Some do a better job than others. There is still nothing like figuring out with the camera while checking the ground glass.

Good luck and enjoy!

cowanw
11-Aug-2010, 15:49
1. (I'm not sure what you mean by focusing above the ground in your post.)

I think he means don't waste half your depth of field underground.
Regards
Bill

11-Aug-2010, 20:41
I agree with the others that

The math isn't that important.
The best way to include more of the foreground is to use falling front.

I would add one thing: unless your subject is planar (and it sounds as if yours isn't), you usually want the rotation axis slightly below ground (and if you check most of Merklinger's examples, that's where he puts it), so you'd use less tilt than you calculated. I hardly ever calculate tilt, but it's possible to use the formula as you have done to calculate the maximum tilt you'd normally use. This really just another way of saying what's been said here time and time again: a little tilt goes a long way.

The effect of pointing the camera down? Recall that J is measured in a direction parallel to the image plane, so if you tilt the camera forward by 5 deg, you theoretically would divide the vertical distance by the cosine of 5 deg. But the cosine of 5 deg is 0.996, and the difference in the calculated tilt is far less than I can accurately read, so unless you point the camera waaay down, it's usually not something to worry about.

I think "look at the groundglass" may be a bit of an oversimplification for setting tilt. I'd suggest reading QT's How to focus the view camera (http://www.largeformatphotography.info/how-to-focus.html) for arriving at the optimal tilt in a systematic way.

Alan Davenport
11-Aug-2010, 21:12
I think "look at the groundglass" may be a bit of an oversimplification for setting tilt.

Every possible movement in a view camera affects one (or both) of only two things: what appears in the field of view, or what is in focus. And the image on the groundglass is the final arbiter of both. It really is that simple.

11-Aug-2010, 21:41
And the image on the groundglass is the final arbiter of both. It really is that simple.

The groundglass is indeed the final arbiter, but unless you have a reasonable idea of how to approach setting tilt or swing, it's easy to fiddle around forever and simply confirm that you can't get everything sharp (or you need use f/64). QT's article discusses a couple of systematic approaches that can greatly reduce the time and effort to reach the point where the final arbitration is successful.

Jack Dahlgren
11-Aug-2010, 21:44
Every possible movement in a view camera affects one (or both) of only two things: what appears in the field of view, or what is in focus. And the image on the groundglass is the final arbiter of both. It really is that simple.

The third thing it sets it the geometric projection onto the film - elongating or foreshortening for example. But also quite visible on the ground glass.

ki6mf
12-Aug-2010, 03:35
Kirk is right. It can take several adjustments to get the look you want. In the days of Polaroid your burned many frames getting the shot. Make a movement, test or look in the ground glass, and then make movements again till its right is the only way to learn. I would keep notes and try measure rough angles to development a sense of what a particular scene takes to get the desired results.

rdenney
12-Aug-2010, 05:15
In the days of Polaroid your burned many frames getting the shot.

Not me. I never found it all that difficult to visualize how my focus plane, lens board plane, and film plane intersect. If the needed movements are subtle, I might have to stand away from the camera a bit and look at things. That is, to me, a better strategy than math. This is a three-dimensional problem best seen in the real three-dimensional world. I am not afraid of the math by any means, but it is not a practical solution in the field. No need to model it with math when the thing being modeled is right there and fully accessible.

And I never used Polaroid to check focus. If I can't see it on the ground glass with a 6X loupe, how am I going to see it on an unenlarged Polaroid print? But I did, and still do, use Polaroid/Fujiroid to check other things that are harder to sense on the ground glass, particularly when using really short lenses in the days before obtaining a Maxwell screen. And I used it to check exposure when I was in doubt concerning a difficult scene.

Rick "who uses the principles to know which direction to go, but the ground glass to determine the final settings" Denney

jonathan_lipkin
12-Aug-2010, 07:12
Thanks all. Went out to shoot yesterday, but left the lens at home!! Will try again this afternoon.
-jl

Brian Ellis
12-Aug-2010, 09:15
Every possible movement in a view camera affects one (or both) of only two things: what appears in the field of view, or what is in focus. And the image on the groundglass is the final arbiter of both. It really is that simple.

It really is that simple in theory, it really isn't that simple in practice. Tilt and swing by themselves aren't always enough. Sometimes you also need to stop down. And if you're photographing in dim light and stopping down it can be impossible to see the image on the ground glass well enough to make meaningful judgments about what's sharp and what isn't. Which is why some people don't rely exclusively on the ground glass.

Brian Ellis
12-Aug-2010, 09:17
Thanks all. Went out to shoot yesterday, but left the lens at home!! Will try again this afternoon.
-jl

Ah, now you're officially a large format photographer. At least you didn't leave the camera.

jonathan_lipkin
13-Aug-2010, 06:34
Thanks for all the helpful and detailed information. I've found a little tilt works, and have read the various articles everyone suggested, practiced in the yard, etc. I think I've more or less got the hang of it.

One last question: is there a way to easily calculate depth of field with tilt? I have used DOFMaster to get a rough idea of DOF with no tilt, but I understand it's more complicated as the film plane tilts. And for some reason, even in bright sunlight I have trouble seeing the GG at f/64 or even f/32. I suppose I could use Merklingers rule that at one hyperfocus distance, the DOF extends above and below the plane of focus by a distance of J.

I'm going to be photographing on the beach, and if there is someone standing a few feet from the camera, and I set the plane of focus on the ground, their feet will be in focus but not their heads, which might look a bit odd. If the person is six feet tall, I would focus at a point two feet up their body and hope the DOF extends up and down enough.

Joanna Carter
13-Aug-2010, 07:11
One last question: is there a way to easily calculate depth of field with tilt? I have used DOFMaster to get a rough idea of DOF with no tilt, but I understand it's more complicated as the film plane tilts. And for some reason, even in bright sunlight I have trouble seeing the GG at f/64 or even f/32. I suppose I could use Merklingers rule that at one hyperfocus distance, the DOF extends above and below the plane of focus by a distance of J.
Now there you go again, trying to calculate stuff! :rolleyes: :D

Forget the books, forget the formulae, go out and experiment. If you want to know what DOF you are going to get, watch the image on the GG as you stop down.

jonathan_lipkin
13-Aug-2010, 08:34
Joanna -

Can't help it - I'm a professor ;).

I would look at the GG, but as I stop down to f/45 I really can't see anything even in bright sun. Ed Kashi once said you need to be a boy scout with your equipment. By that he meant that you should not be fiddling with the controls of your tape recorder (he was talking about interviewing) when you are in front of a subject.

I am going to try to experiment this afternoon in the yard, but do you have any suggestions about seeing the GG more clearly? I know some people place flashlights in the scene.

There are tables in the Merklinger book, but I can't really make sense of them. But if I could get a very rough idea, I could guestimate.

Jack Dahlgren
13-Aug-2010, 08:37
I'm going to be photographing on the beach, and if there is someone standing a few feet from the camera, and I set the plane of focus on the ground, their feet will be in focus but not their heads, which might look a bit odd. If the person is six feet tall, I would focus at a point two feet up their body and hope the DOF extends up and down enough.

I would think that if you are photographing a person on the beach that the plane of focus should align with that person, especially their face. Unless you want their face specifically out of focus.

You can not get everything in focus. Select what is in the scene that you want in sharpest focus. Set the focus plane on those parts of the subject using movements, then stop down to capture what else you think you can get.

If you want a photograph of the sand on the beach, by all means, set the focal plane on the sand, but forget about things sticking far up out of that plane. You just aren't going to get them. Especially if they are close to the camera like your example of a person. You have to choose.

rdenney
13-Aug-2010, 09:19
I have not attempted to work out the math, but I suspect that depth of field can be calculated well enough at any given focus distance on the focus plane. That will result in a wedge-shaped zone with acceptable depth of field, with the thin end of the wedge surrounding the focus plane where it is closer to the camera.

So, if you had a need to know the depth of field around certain three-dimensional subjects that intersected the focus plane at various distances, you could calculate it at each of those subject distances. What I don't know is whether that depth of field is measured normal to the focus plane or along the camera-subject axis. I suspect it's the former, without further investigation.

But I can seen highlights in my images even when stopped down to f/45. I would suggest investigating a focus cloth with better coverage (I like the Blackjacket), and spending a bit more time under it to let your eyes adapt to the dark a bit. Light leaks around the focus cloth close to the rear standard can really keep those irises in your eyes small when you want them large.

In dark conditions, one of those really powerful green laser pointers seems like a neat tool, and I've used it but not when stopped down that far. And if this is a common situation for you, consider investing in a Maxwell screen--it will help a lot.

As far as the time spent in front of the subject, well, that goes with the territory with large-format. Use a stand-in if you don't want to annoy your intended model.

That seems to me a better use of effort. What you see on the ground glass is real, what you model with depth of field calculations is one step removed from reality. All models are false, but some are useful. I believe that all depth of field calculations involve soem approximations and assumptions, not least your standard of sharpness, which will be based on how large your print will be. DOFMaster, for example, is based on an assumed 8x10 print--far too small for our purposes. I usually choose circle-of-confusion values for DOFMaster one quarter what they do for the same formats.

Rick "whose standard of sharpness is what looks crisp on the ground glass with a 6x loupe" Denney

Brian Ellis
13-Aug-2010, 09:26
Joanna -

Can't help it - I'm a professor ;).

I would look at the GG, but as I stop down to f/45 I really can't see anything even in bright sun. Ed Kashi once said you need to be a boy scout with your equipment. By that he meant that you should not be fiddling with the controls of your tape recorder (he was talking about interviewing) when you are in front of a subject.

I am going to try to experiment this afternoon in the yard, but do you have any suggestions about seeing the GG more clearly? I know some people place flashlights in the scene.

There are tables in the Merklinger book, but I can't really make sense of them. But if I could get a very rough idea, I could guestimate.

Very good questions (don't be put off by people who tell you to just go out and photograph, that's fine for some people but others need something more systematic).

I'd strongly suggest that you spend some time reading and understanding the two articles by Q.T. Luong linked on the home page of this forum. One deals with focusing the view camera, the other deals specifically with the question you ask above, i.e. selecting the f stop.

If you take the time to understand and then apply the information there all of your focusing and depth of field questions will be answered and you'll have an easy, quick, simple to use system of focusing and selecting the optimum f stop without having to rely on the ground glass, which as I mentioned in my previous message isn't always possible to do.

As an aside, I spent some time reading one of Merklinger's booklets dealing with the hinge rule and other matters. For me that was more more information than I needed. I also thought that much of his system worked better in the studio where it's possible to measure things easily but wasn't so useful when photographing outdoors. Just my opinion of course.

jonathan_lipkin
13-Aug-2010, 10:05
Thanks again everyone for the advice. I've been shooting for about two weeks and have run into the limit of what I can do under the cloth and by looking at the GG. I'm going to take everyones advice into consideration and go out and shoot this afternoon. I'll every try to remember to bring the lens this time!

As a footnote, I've been teaching digital photography for nearly two decades and have always tried to strike the right balance between reading and doing. Students are always chomping at the bit to use photoshop without understanding what they are doing. Getting that balance right is tricky, both for them and for me.

Again, thanks everyone for taking the time to post such thoughtful and lengthy replies.