..open questions regarding use of chamonix f1..

[psy501]

..hi..
..about two weeks ago i opened a thread because a friend of mine and me got us two chamonix f1 after having used two speed graphics and encountered some problems in using the cameras we did not encounter with the speeds..

http://www.largeformatphotography.in...pics-attached)

..with the help of the forum (and with hugos help (he was really great)) we could rule out that there is something wrong with the cameras..
..its not..they are absolutely fine, but it seems we still don't know some things we should know to get the results we are trying to get..

..in the above mentioned thread there was really fine advice for theory and practical work and i more and more am understanding things like the hinge line etc, but there are things about the camera that despite all theory i don't understand..

..so..

1) it is said that the "dotted lines" on the ground glass of the chamonix is the line along that objects stay in focus when applying rear tilt..is this right and also why is this if i am applying rear tilt around the bottom axis..objects placed on a dotted line above the bottom axis should shift out of focus if tilting the rear if i understand it right, so this sounds unlogic to me..maybe it isn't, but please help me understand..

..more to come but i am planning to ask my questions in a cumulative order as maybe some things i want to ask are answered by the replays i get for this..

..any help would be highly appreciated..

..thx in advance, erik..

[Kevin Crisp]

Personally I think you are getting too bogged down in theory. A wonderful thing about the ground glass is that you can actually SEE the effect of changes you make to the many movements that are available. Look at the glass and tilt the lens and you'll see the effect of that. Ditto on back tilt. You will then have an intuitive grasp without concerning yourself with the S principal. Movements are well and good, but truth be told most of us don't use them that often in a big way.

After many years of using a view camera, I use front rise often to square things up. I love having trees and buildings that aren't leaning. And some back tilt or front tilt a little -- sometimes -- and that is it.

[psy501]

2) also how do you focus correctly and estimate what will be sharp and also estimate the depth of field ?

..background for this question is that that friend of mine tried to take a shot with a nikkor f9/90mm and first set the camera to zero, leveled it, focused using the ground glass with a loupe, also used the reflex viewer and applied front tilt and rear tilt, then again controlled for correct focus and then closed the lens to f32 and took the shot..
..trying to judge composition and focus and focus plane(s) closed down is not possible as apart from very very well lit objects and settings you will see literally nothing..
..so if composing and then shutting down do you "estimate" the outcome or are there some tricks we don't know..
..i never thought that i would have to ask for correct focusing in my life, but it seems that i have to..
..large format makes you bow your head in respect for things you falsely thought are no problem for you..:-)..
..thx for any advice/your procedure..

[dave_whatever]

When using the rear asymmetric tilt you only need to worry about the bottom dotted line on the ground glass, the one about which the glass is tilting. Things on this line stay in focus (typically a distant object) and you then bring foreground objects into focus by tilting. Do not worry about the top dotted line, that's only there for if you ever mount the camera's back the other way up!

In terms of estimating depth of field when stopped down, you can either rely on observing the depth of field on the ground glass as you stop down (assuming your loupe is strong enough to give you an fair idea that will look sharp when you print at whatever size you print at, and that you can even see anything at f/32), or you can divide yourself some kind of DOF scale to implement on the camera's focussing knob. This is my preferred method. There are loads of articles or forum posts on this on the web. How you define your DOF scale is up to you, I use the Ken Rockwell method (probably the most/only valuable article on his site) which is sort of a very strict worst case DOF scale.

[N Dhananjay]

Typical real world subjects can be complicated to work with because they require estimating a best plane of focus (and using movements to get there) and still requiring smaller stops for DOF to get objects not in that plane looking sharp. I would suggest starting with very simple subjects till you get the hang of movements. The easiest is to start with something like the plane of the floor. Or if you have access to a long scale or ruler, have that on the floor. You can easily focus on the numbers etched on the scale. Start with the camera zeroed. Let's say you focus on the 24" mark - the 12" and 36" mark will be out of focus and require DOF. Now use your movements/focus to get the 12" and 36" marks simultaneously in focus (the 24" should also be in focus). This exercise should give you a feel for how to use your movements to move the plane of focus around when there is no DOF requirement.

Next move onto subjects in 3 dimensions and not just in 2 dimension (i.e., on a plane). Let's say you have a scene with a stone in the foreground of a flat field with a row of trees in the distance. Or use the scale but now put a vase or bottle at the 36" mark. So you can use movements to get the entire scale in focus wide open (i.e., the plane of focus lies along the scale) but the bottle is sticking out of the plane and so while the bottom of the bottle is in focus, the top is not. First set up everything zeroed and look at DOF without movements (i.e., they way you would use DOF on a camera without movements). So focus on the nearest and furthest object in the picture and see what the focus spread is - this is easy to do with a millimeter scale on the camera base but you can also estimate it as the number of turns of the focusing knob etc. I then try to imagine where I want a plane of focus running through the scene - for e.g., from the 12" mark on the scale to the middle of the bottle at the 36" mark. In a landscape situation, this might be something like from the stone nearest to me to the middle of the tree in the distance. I then set tilt (or whatever movements are required) and adjust focus to get those two objects in focus and now again look at the focus spread required to get everything in focus. That is, the movements put the 12" mark and the middle of the bottle in focus but the 36" mark and the top of the bottle are out of focus . Or in the landscape situation, getting the stone and tree in focus does not guarantee that other things in the scene (for e.g., the ground in the middle distance and the top of the trees) are in focus and so I need to stop down to get DOF to get the ground in the middle distance in focus - the hope is that the new plane of focus makes less demands on DOF. If the focus spread is less in the second case, you know the movements help.

Remember this is all done with the lens wide open so you should be able to see things snapping into focus easily - and you estimate the focus spread to see how much DOF you require at each setting. Once you have what looks like the smallest focus spread, you can start stopping down the lens while checking for the furthest out of focus object to come into focus (and then maybe stop down an extra stop or two for insurance).

As you practice this, you will find you develop an intuition for where to put the plane of focus and it becomes very fast and practiced.

Good luck, DJ