LFP & deep DOF?

Hi folks,

As of yet, the largest i've shot is 6x7, but i'm mulling over also getting into 4x5 (or even higher).

I'm mostly doing arty studio photography and i've read that as you go up to 4x5 and higher, deep DOF becomes progressively harder to achieve over short (studio or portrait) distances.

Is this the case?

I've checked out a lot of ULF portraiture and indeed, that work always has paper-thin DOF, which isn't the look i want to achieve.

My motivation is to be able to make really massive prints with high resolution. So that people can walk right up to the print and not see pixels or too much grain.

Thanks!

Dazzer123 said:

as you go up to 4x5 and higher, deep DOF becomes progressively harder to achieve over short (studio or portrait) distances.

Click to expand...

Since 4x5 (and larger) tends to use lenses with fairly long focal lengths (compared to small and medium formats), the close-distance depth of field is necessarily shallow - it's the nature of lenses. A lens has the greatest practical depth of field when focused on its hyperfocal distance, and that distance (from the film plane to the closest object in focus when the lens is set to infinity) increases as focal length increases. Essentially, a 90mm lens will always exhibit the same depth of field, no matter what format. So it's not the format size but the fact that you generally will be using lenses of long focal length to get coverage and a "normal" kind of view. (90mm would practically be fisheye on a 16x20 camera but a good portrait length on 35mm and basically normal for 6x7.)

The amount of depth you can get depends on the focal length of the lens, the aperture (of course), and the kind of photos you want to take (how close you want to be to the subject).

Don Heisz said:

Since 4x5 (and larger) tends to use lenses with fairly long focal lengths (compared to small and medium formats), the close-distance depth of field is necessarily shallow - it's the nature of lenses. A lens has the greatest practical depth of field when focused on its hyperfocal distance, and that distance (from the film plane to the closest object in focus when the lens is set to infinity) increases as focal length increases. Essentially, a 90mm lens will always exhibit the same depth of field, no matter what format. So it's not the format size but the fact that you generally will be using lenses of long focal length to get coverage and a "normal" kind of view. (90mm would practically be fisheye on a 16x20 camera but a good portrait length on 35mm and basically normal for 6x7.)

The amount of depth you can get depends on the focal length of the lens, the aperture (of course), and the kind of photos you want to take (how close you want to be to the subject).

Click to expand...

Ok, thanks for the info!

So for studio work, where you want to have good depth of field between say 4 & 7 foot distance, is 4x5 do-able, or is that even a stretch?

I should mention i'm only photographing static subjects without flash, so small apertures and long exposure times are no problem.

Here's a calculator to get an idea-


You'll need to determine an acceptable circle of confusion.

Here is something to be aware of: if you change focal length but maintain the same framing, DOF will stay the same at the same aperture. Here's a good overview of what you are dealing with; more to the end they get into general concepts and working examples.

It will also depend on enlargement magnification. How big are you planning to print?

It would be helpful to state the size of the “really massive prints” you have in mind, as well as the subject-to-lens distances available in your studio and the depth of field you require. Another useful dimension is the horizontal field width you want to record. All of these will help you get meaningful answers.

I see that in post #4 you specified a range of subject distances from 4 to 7 feet (about 1.22 to 2.13 meters).

Standard pre-cut printing papers are usually 8” x 10”, 11” x 14”, 16” x 20”, 20” x 24”, and 30” x 40”. Larger sizes can be cut from continuous rolls of paper up to 56” in width. As you might expect, making significantly large prints can get expensive.

https://www.bhphotovideo.com/c/products/Black-White/ci/802/N/4288586366?filters=fct_size_373:30x40in

https://www.bhphotovideo.com/c/products/Black-White/ci/802/N/4288586366?filters=fct_size_373:56in-wide-rolls

Dazzer123 said:

So for studio work, where you want to have good depth of field between say 4 & 7 foot distance, is 4x5 do-able, or is that even a stretch?

Click to expand...

4 to 7 feet is completely do-able, especially with static objects. That's how all product photography was done for decades. With a view camera, you get to move the plane of focus around so you can adjust where the actual field (of depth of field) is without really changing your perspective.

Don Heisz said:

4 to 7 feet is completely do-able, especially with static objects. That's how all product photography was done for decades. With a view camera, you get to move the plane of focus around so you can adjust where the actual field (of depth of field) is without really changing your perspective.

Click to expand...

Okay! ... so you mean that i could get everything which is between 4 and 7 feet away in sharp focus?

Dazzer123 said:

Okay! ... so you mean that i could get everything which is between 4 and 7 feet away in sharp focus?

Click to expand...

Ok, calm down a minute. There are a lot of factors at work here. The big one, as people have pointed out, is the degree of magnification. And viewing distance! So here's a calculator showing focus from 4' to 8' at f/45 using a 150mm lens on 4x5. BUT- what is the circle of confusion that they are using? What degree of magnification? Viewing distance? Is film grain going to come into play before depth of field does? WHat about diffraction at small apertures?

https://www.pointsinfocus.com/tools/depth-of-field-and-equivalent-lens-calculator/#{%22c%22:[{%22f%22:19,%22av%22:%2245%22,%22fl%22:150,%22d%22:1585,%22cm%22:%220%22}],%22m%22:0}

(cut and paste full text to get it to show 150mm lens on 4x5 at f/45)

What you want to achieve can be done. And understanding the factors will be helpful to get you going and problem solve if things aren't coming out as you want. At some point you are going to need to shoot some film, do some prints, and see if it works for your art.

Another factor not often thought about but is very real these days if you are going to be doing digital printing- Raster Image Processing- RIP- programs have some amazing sharpening and focus improvement algorithms. I worked at a sign company that had an $8000 dollar RIP program (15 years ago) that could take a 20megabyte file and print it to 4x8 feet at great detail. Very clean, too, not some digitial artifact junk pile.

So you'll need to work at every step of the imaging process and see what can be done to get you where you want to be at each step.

Dazzer123 said:

Hi folks,

As of yet, the largest i've shot is 6x7, but i'm mulling over also getting into 4x5 (or even higher).

I'm mostly doing arty studio photography and i've read that as you go up to 4x5 and higher, deep DOF becomes progressively harder to achieve over short (studio or portrait) distances.

Is this the case?

I've checked out a lot of ULF portraiture and indeed, that work always has paper-thin DOF, which isn't the look i want to achieve.

My motivation is to be able to make really massive prints with high resolution. So that people can walk right up to the print and not see pixels or too much grain.

Thanks!

Click to expand...

Yes,sure,it's part of short-distance shooting, but, large CoC and LF adjustments make up for it.

Dazzer123 said:

Okay! ... so you mean that i could get everything which is between 4 and 7 feet away in sharp focus?

Click to expand...

Look at what @Dan Daniel and the others above have said. You should note that depth of field is not the same as sharp focus. Depth of field is acceptably sharp focus given the enlargement you wish to make and the viewing distance. There really will be a plane of sharp focus (not really a plane, I guess, but the idea is the same) and the distance in front of and after that is a field of lessening sharpness. The closer you can get the things to the plane of focus, the sharper they will be.

Thanks guys,

Yes , i understand that there will always be somewhere that has the sharpest focus, and it falls off from there. How quickly is defined by the DOF.

I'm not looking for ultimate sharpness. If i was, i'd shoot digital, maybe stitch multiple shots together etc.

I just want everything acceptably sharp in a studio environment. No "bokah"or blur.

I don't do any digital sharpening, i don't like it!

Viewing distance is nose pressed right up against the print! Because that's what i do in a gallery, i go right up to it and look closely. I know that's not what most people do, but that's what i do.

Anyway, a lot of good info, thanks, I'm going to go through all the posts!

Not sure how you will be going from film to print, but if scanning is involved and if digital image processing of almost any sort is involved on its way to paper, I'd bet good money that sharpening is happening somewhere along the line. Used properly, it's an integral part of making acceptable images. If you will be having prints made, it's a good idea to talk to the lab people, find out what they find works best, what they can do, etc.

I've seen a fair number of 'over the couch with fifteen foot ceilings' art prints from 4x5 and they all fall apart under the nose to the surface test (you aren't the only one who does this, although many museums and galleries find it distressing). 11x17 contact prints from Timothy O'Sullivan, though, seem to hold up quite well Go figure!

As others have said, depth of field will always be the same between the same focal lengths and apertures. But with large format the focal lengths get longer given the same angle of view. For example a "normal" focal length with full-frame digital/35mm is around 50mm, where a "normal" focal length with 4x5 is around 150mm, so you'll have less depth of field with a normal angle of view with the 4x5 given the same aperture and subject distance.

This is why it takes more powerful lighting to make large format studio photographs - you have to stop down more to get the same depth of field. For example a 100mm lens in small format (35mm) is about the same as a 300mm lens in 4x5. You'll have to stop that 300mm lens down quite a bit to equal the depth of field of the 100mm, often to the point where diffraction will soften the image.

If you want more of the image to be in focus (with a large format camera), most large format cameras have the ability to tilt and swing the lens and/or back. This allows you to alter the plane of focus. In other words you can adjust the camera so that the plane of focus is not parallel to the film plane. This can be used to put more of the image into perfect focus, or conversely to "cut" the plane of focus across only one part of the image, leaving the rest of the image out of focus. Much more creative freedom. This has nothing to do with depth of field - wherever you adjust the plane of focus is where it's truly in focus.

Dan Daniel said:

Here's a calculator to get an idea-

Depth of Field (DoF), Angle of View, and Equivalent Lens Calculator • Points in Focus Photography

Calculate the depth of field (DoF), angle/field of view (AoV & FoV), the equivalent lens and aperture on other formats, and more.

www.pointsinfocus.com

You'll need to determine an acceptable circle of confusion.

Click to expand...

+1. This is an excellent tool, especially if you shoot lots of different formats. The calculations generally match those quoted in old manuals when using the 'Archaic' CoC value.

There is not a great jump from 6x7 and 4”x5”, but there is a noticeable difference.

Regarding post #1

If you describe your setup, then we can offer some information that specifically addresses it.

Here is what is needed.

Once you’ve set up your camera on tripod and framed the scene as you want on the first format,

1. What is the distance from the nearest part of the scene you want well rendered to the lens? This is referenced to the first nodal point of the lens, which is generally about the center of the lens lengthwise. Call this distance D1.

2. What is the distance from the farthest point you want well rendered to the lens, distance D2?

3. What is the focal length of the lens, f1?

4. What is your format? This is needed to calculate the DOF.

5. If you want to reproduce this result from the same lens position on a second format, what is that second format? This will be used to determine f2 on the second format and to determine the required aperture of the second lens.

If we know these values, we can answer your questions.

Example: You’ve set up your 6 x 7 cm camera and 90 mm lens to photograph a studio scene that begins at 1.5 meters from the midpoint of the lens and extends to 2.2 meters. Where is the ideal point of focus and what aperture should you choose for good resolution over this scene?

Here, f1 = 90 mm, D1 = 1500mm, D2 = 2200 mm, and the second format is 4” x 5” (95 mm x 120 mm).

The ideal focus distance is 1784 mm. Set up at target in the scene at that distance, focus upon it, lock the focus, and remove the focusing target.

The required aperture is f/15.3, so set the aperture to f/16. This was computed with a circle of confusion diameter of c = 0.059 mm, which is standard for the 6 x 7 format. You can also choose a smaller value for c, depending on your requirements.

On the 4” x 5” format, the lens position and focus point at the same as with the 90 mm lens on the 6 x 7 cm format.

The equivalent lens on the 4” x 5” format is 150 mm. The required aperture is f/26, so close down to f/32. (Calculations based on circle of confusion diameter of 0.10 mm for the 4” x 5” format).

The photo taken on the 4” x 5” format in this setup should duplicate the one made on the 6 x 7 cm camera. The difference is the size of the negative. Since both of these formats have nearly the same aspect ratio (1.24 and 1.26 respectively), the in-camera framing will be nearly identical.

Before investing in a 4” x 5” camera, lens, and so forth, it would be useful to first make the best photo you can with your existing 6 x 7 cm equipment on a fine-grain film known to produce good resolution. Print this negative at the size you want and determine whether it has sufficient resolution for your requirements. You might find that satisfies your desire for a large finely detailed print.

Kodak T-Max 100 is a good film choice for such work. The lighting also plays an important role as well. Some lighting setups will reveal detail better than others.