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.