Hyperfocal distance and focusing

[coops]

I never gave this any thought with my old digital cameras but I have aquired an RB67 and several lenses and want to use them this weekend. I have been doing some reading about HF distance but I am not sure about just where to focus. For example, a building facade is 100 meters away, but I want a few flowers in the shot, and they are about 3 meters away from me, in the foreground. At F/22 (using a 65mm lens) I should get good sharpness between 1.5 m and infinity. Do I focus on the facade? Some people say to focus 1/3 of the way into the shot, in this case 30 meters.
Appreciate the feedback

[Jack Dahlgren]

I think your lens should have a depth of field preview lever. Stop down and try it.

Hyperfocal distance is an inexact thing as it depends on "acceptable" focus.
With a subject with something close and rather far I'd tend to focus closer since the objects in the foreground are going to be a lot larger and people will expect them to be in focus. It all depends on what you want out of the image.

[coops]

I think your lens should have a depth of field preview lever. Stop down and try it.



Thanks Jack. Yes the lenses do hjave a depth of field preview so here is the next question. The image looks dimmer when I use this, but what am I looking for? Is what is visible sharp? Or the opposite? Thanks again.

[SocalAstro]

I never gave this any thought with my old digital cameras but I have aquired an RB67 and several lenses and want to use them this weekend. I have been doing some reading about HF distance but I am not sure about just where to focus. For example, a building facade is 100 meters away, but I want a few flowers in the shot, and they are about 3 meters away from me, in the foreground. At F/22 (using a 65mm lens) I should get good sharpness between 1.5 m and infinity. Do I focus on the facade? Some people say to focus 1/3 of the way into the shot, in this case 30 meters.
Appreciate the feedback

According to the Photocalc app I use on my iphone using a
65mm lens, 6x7cm format, .06mm c.o.c. criterion

f/11 Focus at 6.4m; 3.2m to infinity in focus
f/16 Focus at 4.4m; 2.2m to infinity in focus

Hope this helps,
Leon

[Brian Ellis]

Trying to focus using a hyperfocal distance doesn't work all that well outdoors or any other time in my experience. I'd just forget that method.

The idea of focusing 1/3 of the way into the scene is different from hyperfocal distance. For one thing it's often impossible to figure out where 1/3 is and also because 1/3 is only an approximation to begin with, the actual distance depends on several variables such as how far away you are from the subject on which you're focusing and on the focal length of the lens. I'd forget about it too.

All of these formulas that try to tell you where to focus assume a particular degree of enlargement (stated another way, they assume a particular size for the circle of confusion), which may or may not be accurate for you. Which is another reason why they're pretty much useless IMHO.

When you're using the depth of field preview button you're looking to see if everything you want to be sharp in the photograph looks sharp in the viewfinder with the button depressed. It works o.k. with wider apertures and good light but it's difficult to use with smaller apertures like f16, f22 etc. and/or poor light because the image in the viewfinder is too dim to see much of anything. It helps to wait a little while and let your eye adjust to the darkness in the viewfinder but if the light isn't very bright and you're stopping down to f16 or 22 you'll never be able to tell much from the depth of field preview.

Sometimes you just have to wing it based on experience. E.g. if you want something 5 feet away and 200 feet away and everything in between to be sharp and you're using a long lens, you know you'll have to stop down to f22 or whatever the smallest aperture is on your lens.

[Steve M Hostetter]

Coops,, If I were shooting with a wide angle lens and I wanted everything in the viewfinder to be in sharp focus I would be focusing to the hyper focal distance whether I was aware of it or not.. 99% of the time

There again,, I think Jack and Brian raise good points in regards to every different kind of situation ...

[ic-racer]

Read about "focusing a view camera" on the Home Page of this site.
Since you can't get your focal spread easily (unless you calculate focus ring rotational distance to lens extension) the good people at Mamyia have done the homework for you. You can use the depth of field indicators on the lens. You will just straddle the distance of you near and close objects between two of the depth of field lines. Then use the indicated aperture. For critical work you will likely need to stop down one to two stops beyond what is indicated by the marks, but you still must straddle the two focal points both on the same indicated f-stop number.

[Leonard Evens]

The point about the hyperfocal distance is that if you focus at that distance, in principle, everything from half that distance to infinity will be in focus. If you focus in front of the hyperfocal distance, your depth of field won't extend to infinity. If you focus at greater than the hyperfocal distance, your near focus point will be further out than necessary.

Of course, hyperfocal distance depends on the f-stop and your criterion for sharpness, i.e., your maximal acceptable circle of confusion. It is also calculated for a perfect lens and ignores diffraction. So, in practice, it is at best a rough guide. When I use such methods, I focus at the calculated distance and then stop down from half to a full stop further.

The hyperfocal distance is given by a relatively simple formula

f^2/(Nc)

where f is the focal length, N is the f-number, and c is the maximal acceptable circle of confusion. A reasonable choice for c for 4 x 5 photography is about 0.1 mm, but some people may prefer a smaller number.

You would give the focal length f in mm, and the answer would be in mm. To convert to inches divide that result by 25.4 and to convert to feet divide that result by 12.

The one third into the scene rule has never made much sense to me. It is supposed to be the point at which the rear depth of field is twice the front depth of field. It is not hard to see that this only occurs when you focus approximately at one third the hyperfocal distance. But when you focus at that distance, you can be sure the depth of field won't extend to infinity. The best I can tell is that it is a rule which might make sense when you want a scene mostly in the middle distance and you don't want to think about it too much.

The rule which most of us use requires little calculation. Focus first on the furthest point you want in focus, mark the position on the rail, then focus at the nearest point you want in focus and mark that position on the rail. Measure the distance, called the focus spread, between those points in mm and then focus at the point on the rail halfway between them. If you multiply the focus spread by 10 and divide by 2, that will give you a rough estimate of the proper f-number to use to be sure near and far points are in focus. But, as noted above, this is based on assuming a perfect lens, so it is prudent to stop down half to a full stop beyond that. This may work well as long as you don't have to stop down too far. If you end up stopping down to f/32 or beyond, diffraction may enter. In that case, you want to try to balance the effect of defocus against that diffraction. Pau l Hansma has developed a rule for doing this. It is described along with other approaches at the LF website at

/www.largeformatphotography.info/fstop.html

[Jack Dahlgren]

The point about the hyperfocal distance is that if you focus at that distance, in principle, everything from half that distance to infinity will be in focus. If you focus in front of the hyperfocal distance, your depth of field won't extend to infinity. If you focus at greater than the hyperfocal distance, your near focus point will be further out than necessary.

Of course, hyperfocal distance depends on the f-stop and your criterion for sharpness, i.e., your maximal acceptable circle of confusion. It is also calculated for a perfect lens and ignores diffraction. So, in practice, it is at best a rough guide. When I use such methods, I focus at the calculated distance and then stop down from half to a full stop further.

The hyperfocal distance is given by a relatively simple formula

f^2/(Nc)

where f is the focal length, N is the f-number, and c is the maximal acceptable circle of confusion. A reasonable choice for c for 4 x 5 photography is about 0.1 mm, but some people may prefer a smaller number.

You would give the focal length f in mm, and the answer would be in mm. To convert to inches divide that result by 25.4 and to convert to feet divide that result by 12.

The one third into the scene rule has never made much sense to me. It is supposed to be the point at which the rear depth of field is twice the front depth of field. It is not hard to see that this only occurs when you focus approximately at one third the hyperfocal distance. But when you focus at that distance, you can be sure the depth of field won't extend to infinity. The best I can tell is that it is a rule which might make sense when you want a scene mostly in the middle distance and you don't want to think about it too much.

The rule which most of us use requires little calculation. Focus first on the furthest point you want in focus, mark the position on the rail, then focus at the nearest point you want in focus and mark that position on the rail. Measure the distance, called the focus spread, between those points in mm and then focus at the point on the rail halfway between them. If you multiply the focus spread by 10 and divide by 2, that will give you a rough estimate of the proper f-number to use to be sure near and far points are in focus. But, as noted above, this is based on assuming a perfect lens, so it is prudent to stop down half to a full stop beyond that. This may work well as long as you don't have to stop down too far. If you end up stopping down to f/32 or beyond, diffraction may enter. In that case, you want to try to balance the effect of defocus against that diffraction. Pau l Hansma has developed a rule for doing this. It is described along with other approaches at the LF website at

/www.largeformatphotography.info/fstop.html

I don't think that this method is very effective on an RB67. Not saying it couldn't be done, but it would be difficult.

[Brian Ellis]

Read about "focusing a view camera" on the Home Page of this site.
Since you can't get your focal spread easily (unless you calculate focus ring rotational distance to lens extension) the good people at Mamyia have done the homework for you. You can use the depth of field indicators on the lens. You will just straddle the distance of you near and close objects between two of the depth of field lines. Then use the indicated aperture. For critical work you will likely need to stop down one to two stops beyond what is indicated by the marks, but you still must straddle the two focal points both on the same indicated f-stop number.

I'm not familiar with this particular lens but if it's a typical distance scale found on many lenses it's really just a depth of field table and shares the same problems all depth of field tables do, which is that somebody else has decided on what degree of enlargement you'll be doing and is using their idea of what will be an acceptable degree of sharpness to you. Your advice to stop down a couple stops is good but then stopping down further may introduce diffraction problems - perhaps unnecessarily - depending on the final print size.

I don't know, maybe I'm just biased because none of these formula-based systems of determining a focus point have worked well for me. When I tried hyperfocal distances I never got a photograph that was really sharp from half way to infinity. And when I tried to focus 1/3 of the way into the scene I got the same result - there was always something that wasn't sharp, partly because that's an inherently flawed system and partly because figuring out where the 1/3 point is with most landscape photographs is virtually impossible. And distance scales, even when they were on a particular lens, were problematical for the same reason.

But if these methods work for others then maybe I was just doing something wrong, who knows. The only "system" with film cameras that's worked for me is the one referenced in the first sentence of your message but I've never tried to adapt that system to a camera other than a large format camera. A digital camera with Live View is a good solution because unlike the situation with a depth of field preview button, you can actually see what's going on. But obviously the OP isn't using a digital camera.

[tgtaylor]

I'll chime in with a method that I learned from Galen Rowell that works for me.

Assuming the the Mamiya lens is similar to the P67 lens and you want a sharp focus on a foreground that is 5 feet from the camera to infinity:

1. Focus on the foreground that you want sharp and note where that focus point falls on the lens distance scale. I have my 55mm 67 lens out and lets supposed that the red focus arrow on the lens points dead at 5 feet on the distance scale.

2. Now focus on the background that you want in sharp focus and see where that focus point falls on the same distance scale as above which is infinity in this case.

3. Now turn the focus ring to determine which f-stop located on both sides of the red focus arrow encompasses both focus points (5 ft and infinity). My lens indicates that stopping the lens down half-way between f16 and f22 will result in a sharp focus throughout the picture.

4. Since my lens stops at f16 or f22 and not bewteen, I set the f-stop at f22. Galen advised stopping down an extra stop "for insurance."

Thomas

[ic-racer]

I don't know, maybe I'm just biased because none of these formula-based systems of determining a focus point have worked well for me.

I suspect you are using someone else's acceptable circle of confusion size. You need to calculate you own.

[el french]

I'm surprised no one has mentioned Harold Merklinger: http://www.trenholm.org/hmmerk/

[rdenney]

Time for clarity: There is only one focus plane, and it is thin. You cannot make the focus plane thicker by stopping down. Only what falls right on the focus plane will truly be "in focus".

Depth of field does not encompass what is in focus, but rather what appears to be in focus on a given size print. The appearance of focus occurs when the blurry spot on the film that represents a sharp (and arbitrarily small) spot in the scene is still small enough to look sharp in the print. The bigger you print, though, the bigger that blurry spot will be, and the less likely it will appear sharp. Depth of field calculations therefore start with the standard of apparent sharpness selected by the photographer.

Most depth-of-field tables are based on something like the "Zeiss Formula", where the maximum allowable size of that blurry spot is 1/1500th of the frame height, or something in that vicinity. For 4x5, that would be .07mm, which most would consider too large for making big prints that can withstand close inspection. DOFMaster, which I sometimes use on my iPhone and which also has an online calculator, is standardized on an 8x10" print. For that standard, they use a blurry-spot standard of 0.1mm for 4x5. 16x20" is really about the smallest I would want to be able to print, so to use their calculator I have to set that standard (which is called the circle of confusion) at 0.025mm. For 6x7, DOFMaster uses 0.06mm as the standard for 8x10" prints, which means I would want to use 0.015mm for my 16x20" print.

(The Zeiss Formula was based on the assumption that people would not view prints more closely than being able to see the whole print at once, but we all know that people inspect prints more closely than that. For an 8x10" print, close inspection does not preclude seeing the whole print, and I suspect that's why DOFMaster standardized on it.)

For a circle of confusion of 0.015, DOFMaster reports a hyperfocal distance of 41 feet at f/22. When focused at 41 feet, everything from 20.5 feet to infinity will appear sharp to that standard. If you focus at 37 feet and use f/22, you can get your building in focus, but your flower can't be any closer than 19.5 feet. Can't tell the difference between 37 and 41 feet on your focus ring? Neither can I. That's why you have to use the ground glass, preferably with a good magnifier. Or a view camera with movements which makes it possible to tilt the focus plane.

Maybe you don't want to print as large. But you really must consider the standard of sharpness you desire when you set out to use hyperfocal distances, in order to avoid being disappointed when you see the image projected on your enlarger easel or on your monitor after scanning.

Rick "who only uses hyperfocal settings for really short lenses" Denney

[coops]

Thanks for the responses. I understand HD is not exact. I have read several webpages explaining how to achieve this but most contradict each other (not the internet surely). I may not have worded my question well and it may be a case of not being able to see the trees for the forrest, so let me see if I am on the right path here. Using image 1, I have determined the rocks in the foreground are 10 feet in front of the lens. Stopping down to F/22 , 6 feet to 30 feet will be in focus. Is the 10 foot distance my subject and HD? Sometimes those words I think are interchangable. Perhaps not.
But I want the barn in focus, which is about 100 yards back, or at infinity. Using this setting, it will not be in focus. Do I place the infinity symbol as the subject distance mark which would extend focus from 4 feet to infinity? Still focusing at 10 feet?
Or, as in image 2, simply place the infinity symbol over the F/22 mark which places focus between 7 feet and infinity.
Before you call me a bonehead (you would probably be right though) I have seen these examples online as explanations of the "correct" method. Can they all be correct?

Thanks for your patience and time.

[Peter De Smidt]

This is what I do with a Nikon 35mm and medium format cameras with depth-of-field scales.

First, I focus on the nearest scene element that I want sharp, note the distance, and then focus on the farthest scene element that I want sharp, also noting the distance. Next, I look for an aperture spread on the distance scale that's close to what I need. I put the left distance mark for a given aperture on the near distance, and I check to see if the corresponding mark, i.e. the right mark on the scale, covers the far distance. If there's not enough depth-of-field, then I check a smaller stop, moving, say, from f8 to f11. Once I get the right aperture--one that puts the nearest sharp scene element on the left depth-of-field mark, and the farthest scene element that should be sharp on the right depth of field mark--I then stop down two stops more than what is indicated, as testing showed me that Nikon's circle on confusion was good only for a very small print.

So in your case, place the left F22 depth-of-field mark on 10 feet. If the right mark just covers infinity, then you are at the manufacturer's recommend focus distance for that scene. Take a picture. Stop down one stop without changing the focus. Take a picture. Repeat once more. Make prints at the largest size you'd make with that negative. Compare prints. Use the method that gives you the sharpness that you require.

[Peter De Smidt]

Here's saying it another way.

After you've figured out the distances of the near and far scene elements that you want sharp, do the following:
1. Guess an aperture setting.
2. Place the right depth-of-field mark for the aperture chosen such that it lines up with the distance of the far scene element.
3. Look at the left depth-of-field mark for that aperture.
4. If it falls to the right of the left depth-of-field mark for that aperture, then that aperture will give the required depth-of-filed for that picture, according the lens's manufacturer.
5. If it falls to the left of the left depth-of-field mark for that aperture, then you need to use a smaller aperture. If so, pick a smaller aperture, i.e. a bigger f-number, and try again.
6. Once you find the suggested aperture that just places the scene elements between the appropriate depth-of-field marks, close down the further number of stops that your testing indicates is necessary to get your required sharpness.

[BetterSense]

Has anyone ever seen or created a linear DOF scale for a field camera? My Speed graphic has a focus scale on the bed, but I think if you tried to add DOF ticks to the little 'arrow' then it would be pretty hard to read, and of course it would only work with one lens.

[coops]

Here's saying it another way.

After you've figured out the distances of the near and far scene elements that you want sharp, do the following:
1. Guess an aperture setting.
2. Place the right depth-of-field mark for the aperture chosen such that it lines up with the distance of the far scene element.
3. Look at the left depth-of-field mark for that aperture.
4. If it falls to the right of the left depth-of-field mark for that aperture, then that aperture will give the required depth-of-filed for that picture, according the lens's manufacturer.
5. If it falls to the left of the left depth-of-field mark for that aperture, then you need to use a smaller aperture. If so, pick a smaller aperture, i.e. a bigger f-number, and try again.
6. Once you find the suggested aperture that just places the scene elements between the appropriate depth-of-field marks, close down the further number of stops that your testing indicates is necessary to get your required sharpness.

Thanks Peter, will try this.

[Jim Jones]

Has anyone ever seen or created a linear DOF scale for a field camera? My Speed graphic has a focus scale on the bed, but I think if you tried to add DOF ticks to the little 'arrow' then it would be pretty hard to read, and of course it would only work with one lens.

Some years ago there was a magazine article, probably in Photo Techniques, that described this. Interestingly, if my old mind remembers correctly, the DOF marks apply to all focal lengths if the print size and COF remain the same. I don't have time at the moment to research ths further. Probably some LF member can cite the article or recreate the math.

[Heroique]

I have determined the rocks in the foreground are 10 feet in front of the lens... But I want the barn in focus [too], which is ... at infinity.

Several workable answers have gone before. Here’s one more to add to the mix.

In your post #15 – the one w/ the photos of your MF lens – you say your aim is to “focus” both the nearby rocks (at “10 feet”) and the barn (at “infinity”). To keep things simple, let’s assume you like the lens manufacturer’s choices about acceptable focus, and set aside “Zeiss standards,” “COF,” “print sizes,” etc. for the moment.

Five quick steps to select an aperture:

1) Focus your lens on infinity.

2) Next, on your lens’ DOF scale (top portion of photo below), inspect where the various apertures allow closest focus at this infinity-focus setting. (On your particular lens, you’d inspect the “left” brackets. The “right” brackets, since you’re focused on infinity, would have no info above them.)

3) For example, the left bracket for f/16 would land on about 25 feet. That’s the hyperfocal distance for f/16. This simply means that if you re-focus on 25 feet, you’ll keep infinity in focus, plus have everything else in focus down to one-half of 25 feet, namely 12.5 feet. In other words, at f/16 you can’t bring anything closer than 12.5 feet into focus & keep infinity in focus at the same time. (Keep in mind you’re focused on 25 feet to do this.)

Problem is, you need the rocks at 10 feet in focus…

4) Now inspect f/22, whose left bracket lands on about 10 feet. That’s the hyperfocal distance for f/22. At risk of repeating myself, this simply means that if you re-focus on 10 feet, you’ll keep infinity in focus, plus have everything else in focus down to one-half of 10 feet, namely 5 feet. In other words, you can’t bring anything closer than 5 feet into focus & keep infinity in focus at the same time. (Keep in mind you’re focused on 10 feet to do this.)

5) So your thinking at this point might be: “By selecting f/22 and focusing on that particular aperture’s hyperfocal distance – 10 feet – I can keep infinity in focus, plus bring the rocks at 10 feet into focus, plus have 5 additional feet of space in front of the rocks in focus too.”