DOF vs Tilt

[cmcdarris]

I am an amateur film photographer. I have had my own darkroom in my house for 20 years and have always been a dedicated film user. I have just made the leap this week to LF, having purchased a 4x5 field camera. I am learning tilt, shift, etc (Thanks LF Forum and YouTube).

For years I have shot a fully manual medium format camera so I use and understand Depth of Field. In the last few weeks, I have read numerous articles about Large Format cameras and the use of tilt for landscape shots to bring fore and background into focus. My question is this: Why not just use DOF of the large format lens and just leave the Large Format camera “zeroed out”, ie - no tilt? Setting it on f64 will surely give sharp detail from foreground to background in the scene.

Thanks for the input.

Charlie

[Bob Salomon]

Tilting or swinging lets you control the plane of sharp focus. Depth of field is the range of ACCEPTABLE sharp focus in front and behind the point of sharp focus.
So when you do a tilt or a swing you modify the plane of sharp focus, stopping the lens down increases the depth of acceptable sharp focus in that plane.
When you stop the lens down as far as 64 you will not get sharp results because of diffraction. Most 45 lenses are diffraction limited to f22.

Since DOF runs normally 1/3rd towards the camera from the point focused on and 2/3rds away from that point the first thing you need to learn is where to focus to maximize your depth of field. If you are doing macro then the DOF is 50/50 from the point focused on.

[Eric Leppanen]

Setting it on f64 will surely give sharp detail from foreground to background in the scene.

All too often it doesn't, and that is part of the challenge of shooting large format.

With 4x5, normal and longer lenses cannot get a very near foreground and infinity background in simultaneous focus simply by stopping down, even to f/64. You either need to decide which portions of your composition can go out of focus, or apply movements (assuming they work for the scene) to optimize the plane of focus so less stopping down is necessary. Depth of field becomes even more limited if you migrate to larger LF formats.

Additionally, stopping down to f/64 will noticeably soften your image due to diffraction, assuming you are enlarging and not contact printing (although some folks don't print large enough for this to matter). F/64 also means slower shutter speeds, making camera shake, subject movement or film reciprocity failure potential issues.

Since you already have your LF camera, I suggest applying the f-stop selection technique described in this article and experimenting with how much stopping down works for you, given your shooting style and preferred choice of subjects:

http://www.largeformatphotography.info/fstop.html

Many folks new to LF are surprised by how much stopping down is required to get everything into acceptable focus!

[ic-racer]

Setting it on f64 will surely give sharp detail from foreground to background in the scene.

??

[cmcdarris]

??

Regarding medium format cameras and looking at a Depth of Field calculator (or just using the distance markings on my medium format lens), I can see that a landscape composition with an 80mm lens, subject 50 feet away, and lens at f22 yields a Depth of Field from 8 feet to infinity.

Considering a Large Format lens, I was just assuming it would work the same, as the DOF Calculator shows a 150mm LF lens (comparable to an 80mm MF lens) focused at a subject 50’ away and set of f64 yields a DoF of 9 feet to infinity.

Many thanks to the above responses, as I see there is more to consider with Large Format lenses.

[Jac@stafford.net]

Regarding medium format cameras and looking at a Depth of Field calculator (or just using the distance markings on my medium format lens), I can see that a landscape composition with an 80mm lens, subject 50 feet away, and lens at f22 yields a Depth of Field from 8 feet to infinity.

In the instructions for an earlier Hasselblad Super-Wide they made it clear that if one were to make particularly great enlargements, he should choose (at least) one stop smaller than the lens' guide. I agree, with experience making 40x40" enlargements. Sorry I do not have the full image here. (http://www.digoliardi.net/lib.jpg)

Very much of perceived DOF depends upon viewing distance.
.

[Bob Salomon]

Regarding medium format cameras and looking at a Depth of Field calculator (or just using the distance markings on my medium format lens), I can see that a landscape composition with an 80mm lens, subject 50 feet away, and lens at f22 yields a Depth of Field from 8 feet to infinity.

Considering a Large Format lens, I was just assuming it would work the same, as the DOF Calculator shows a 150mm LF lens (comparable to an 80mm MF lens) focused at a subject 50’ away and set of f64 yields a DoF of 9 feet to infinity.

Many thanks to the above responses, as I see there is more to consider with Large Format lenses.

Not quite. The circle of confusion for 45 is different then the CoC used for medium format. Since the film size is larger the film needs less enlargement for 45. Conversely the CoC for 35 is simarly different then MF or 45. There are pocket calculators to compute DOF as well as Scheimflug for formats from 35 to 810 like the Rodenstock/Linos one.

[Eric Leppanen]

What enlargement factor or print size does your depth of field calculator assume? Often the depth of field markings on small and medium format lenses assume an 8x10 inch print size. If you are printing larger than that, then you will need more stringent calculations.

[MAubrey]

Not quite. The circle of confusion for 45 is different then the CoC used for medium format. Since the film size is larger the film needs less enlargement for 45. Conversely the CoC for 35 is simarly different then MF or 45. There are pocket calculators to compute DOF as well as Scheimflug for formats from 35 to 810 like the Rodenstock/Linos one.

If the OP is using http://www.dofmaster.com/dofjs.html as his DOF calculator, then it's already taken into account the difference in the CoC's between the two formats.

Edit: I don't know what he's using, but in http://www.dofmaster.com/dofjs.html, the 4x5 calculations for f64 are right, but the 6x6(?) calculation for f/22 are different--the markings on his lens aren't quite accurate to the caculator...

Additionally: for both formats, focusing at 50ft is unnecessary since the hyperfocal distance is much closer than that. If you open up a 4x5 lens to f/32, you can focus at 23.6ft and get everything in focus from 11.8ft to infinity.

[Bob Salomon]

If the OP is using http://www.dofmaster.com/dofjs.html as his DOF calculator, then it's already taken into account the difference in the CoC's between the two formats.

Edit: I don't know what he's using, but in http://www.dofmaster.com/dofjs.html, the 4x5 calculations for f64 are right, but the 6x6(?) calculation for f/22 are different--the markings on his lens aren't quite accurate to the caculator...

Additionally: for both formats, focusing at 50ft is unnecessary since the hyperfocal distance is much closer than that. If you open up a 4x5 lens to f/32, you can focus at 23.6ft and get everything in focus from 11.8ft to infinity.

You can open up a lens to, say, 5.6 but you would stop down a lens to f32. But on 45 that would also be in diffraction. Most lenses for 45 perform optimally at f22.

[Doremus Scudder]

... My question is this: Why not just use DOF of the large format lens and just leave the Large Format camera “zeroed out”, ie - no tilt? Setting it on f64 will surely give sharp detail from foreground to background in the scene. Thanks for the input.

Charlie

Charlie,

LF photographers are always trying to optimize aperture and shutter speed. The reasons for this are directly related to the size of the film (i.e., more important the larger the format). There are many situations where one simply can't stop down enough to get everything into sharp focus without either getting into diffraction degradation or ending up with a shutter speed that is impossible to use with a moving subject.

Firstly, as has been pointed out, the sharpest aperture for most LF lenses is around f/22. Ideally, one would want to shoot at that aperture or as close to it as possible. So, when the DoF at f/22 won't do the job, one can often use tilt and swing to reposition the plane of sharp focus in order to be able to shoot at f/22 or thereabouts. For many shots, especially those with tall objects close to the camera and important distant objects, there isn't much tilt you can apply. However, you'd be surprised how much even a little helps with aperture choice. I shoot architecture a lot, often a building with a bit of foreground. I can often save a stop or two by simply tilting the front standard so that the plane of sharp focus includes a close foreground object and the top of the building This then becomes my "near" and whatever is farthest from that becomes my "far." I can often reduce focus spread significantly (see the articles on the LF home page about focusing the view camera and choosing the f-stop). FWIW, however, my most used f-stop is f/32. This gives me prints up to 20x24 without enough diffraction degradation to bother me.

Secondly, we often have to use a faster shutter speed than would be optimal in order to stop movement in the scene, especially with landscapes. Wind, moving water, etc. require relatively fast speeds, which in turn, need wider apertures. Again, we can often use tilt/swing to reposition the plane of sharp focus to allow us to get the objects in the scene in sharp-enough focus and gain a stop or two wider aperture which can then allow the shutter speed to be faster.

A third consideration is image manipulation. Often we want to emphasize a foreground object, emphasize convergence or change the relative size of objects in the scene. This is done by tilting the back. Many use wide apertures and tilt/swing to manage the in-focus and out-of-focus areas in their images. These, however, are less-directly related to DoF and aperture size.

Hope this helps,

Doremus

[Pere Casals]

A Doremus pointed, a tilted plane of focus is not only used to place subjects in focus, but also to place objects in the scene out of focus, this allows for awesome creative effects.

Like in this image https://www.flickr.com/photos/coltonstark/34414692831/in/faves-125592977@N05/

or this one, there is OOF under flowers, and in the lake:

https://www.flickr.com/photos/timparkin/37619135541/in/faves-125592977@N05/

[Andrew Plume]

Doremus

Although it isn't pertinent to this thread, I just came across an article from you in an old edition of 'View Camera' which featured this terrific image:-

http://www.doremusscudder.com/Death-Valley.htm?m=66&s=570&m=66&s=570&id=63

regards

Andrew

[Doremus Scudder]

Doremus

Although it isn't pertinent to this thread, I just came across an article from you in an old edition of 'View Camera' which featured this terrific image:-

http://www.doremusscudder.com/Death-Valley.htm?m=66&s=570&m=66&s=570&id=63

regards

Andrew

Andrew,

Thanks for the compliment and directing people to my website :) I think the image in the article was the first one in the gallery, "Zabriskie Point, Dawn" in case any are curious as to exactly which image you are referring to.

BTW, my article on basic field camera movements used to be on the free articles page of the View Camera website. I'm not sure it's still there. If anyone is interested, I'll happily send them my pdf-proof of the article (complete with typos).

Best,

Doremus

[Bernice Loui]

Modern LF lenses tend to be optimized for f22, but this is not always the case for vintage lenses. The f22 ideology appears to come from the LF-Group f64 of everything in the image must be sharp. Images made on LF sheet film does not always need to have it's optics stopped down to f22 or smaller to achieve overall image sharpness. There are many factors that affect overall image sharpness and the aperture required to achieve this.

Example, Group image made using a 8 1/2" Kodak Commercial Ektar in barrel with a Sinar shutter on a Sinar 5x7 camera on a honking heavy Gitzo tripod with Sinar Pan-Tilt head. Taking aperture was full open, f6.3. This had to be due to the time of day, potential movement of the individuals in the image and slow film speed. The resulting image is plenty sharp for prints up to 4-5x.

https://secure.meetupstatic.com/photos/event/5/4/f/8/highres_416541752.jpeg


Point being, there are a host of factors that affect overall image sharpness and the orthodoxy of stopping down to f22 or smaller is required being simply not always true.
It does require camera stability (weight), precision (often metal with precision made mechanicals), proper use of camera movements as needed, heavy and stable tripod then optics that are not optimized for the f22 and smaller aperture ideology. As perviously mentioned, f22 is not a commonly used aperture on 5x7 for the images I'm making. Typical would be f16 with carefully applied camera movements for image made near infinity focus or far distances, using larger apertures is often much less significant problem. At shorter image distances (lesser increased the problem greatly), achieving sharp definition overall can become challenging to not possible.


The microscope image makers using film have a similar problem of exposure time due to low level of light reaching the imager. One of their solutions is similar to making night images with film, increase the film exposure time to allow the image to form on the film over an extended duration of time. This reduces the unstable images that are out of sync with the image being gathered over the time of exposure.



Bernice

[MAubrey]

You can open up a lens to, say, 5.6 but you would stop down a lens to f32. But on 45 that would also be in diffraction. Most lenses for 45 perform optimally at f22.

Yes, I know. I was just commenting on DoF calculations.

[Tobias Key]

Although it doesn't seem like it when you start out, tilts and shifts actually make your life a lot easier and are pretty intuitive to use in real-life situations. I came up from shooting medium format and wouldn't be without movements and my LF camera now . It really does make certain pictures much easier to capture and shifts are brilliant for fine tuning compositions on a tripod.

[DG 3313]

I have heard it called depth of focus. You can change the plane of sharp focus now that you are a 4x5 guy.

To the OP: knob focus on the far.....tilt for the near. Do this wide open and then re-focus a few times as needed. You will be amazed what you can get kinda sharp at 5.6 with a 210 mm lens. The subject, the focal length of the lens and the distance to the subject have everything to do with being able to get the focus right.

Sometimes you just cant get it all.

When you get all you can wide open.....then you stop down to F-16, 22, 32 to get the rest. It's not fast but, it can be fun.

Don

[Andrew Plume]

Thanks Doremus, appreciated indeed

regards

Andrew