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06-09-2019, 09:34 AM   #1
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Hyperfocal / landscape focus advices are wrong

Since I've gotten the K1, I happen to pay more attention to focal length, aperture and where to focus the lens for landscape exposure. A while ago I had open a thread about what aperture setting to select depending on the focal length because I wasn't satisfied with the f11 set by the Pentax hyper-program for "all in focus" exposures.


So I came up with a rule of thumb for myself (using the Pentax K1 / full frame mode). My rule of thumb was: << aperture should be stopped down the an f number that is the 2 x FL/10 when the foreground is a flat terrain and the camera is positioned horizontally at the eye level of the photographer.

For instance: FL = 20mm => aperture = f4; FL = 35mm => aperture = f7.1; FL =50mm => aperture = f10. So far, that rule I set for myself worked quite well under 50mm focal length.

Then I questioned myself about where to focus: "should I focus on the foreground? half way through the frame? Or should I focus on the background?".

I found some videos on youtube, there are couple of video where the advice given says "you should measure the distance between the camera and the subject you want in focus, divide that distance by 2 and focus there" or "you should focus at twice the hyper-focal distance".

Links here:


Then I installed an DoF / hyperfocal distance calculator on my smartphone. Trying various focus distances in the app, I found that the near plane of focus doesn't change as much as the farther plan of focus when the distance of focus is increased. So all that means for me: if I focus at infinity, I get the largest amount of the scene in focus, and hyperfocal focusing doesn't actually provide the deepest amount of the scene in focus.

And indeed, the f11 by the Pentax hyperprogram on full frame, somehow deliver the most sharpness out of a landscape shot horizontally at eye level.

06-09-2019, 09:53 AM - 1 Like   #2
dms
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The proper focus distance is the average of the inverse distances. So if the closest desired distance is dc, and farthest is df, then the optimum d,
is: 1/d = 1/2 (1/dc + 1/df).

Three examples:
dc = 5 ft, df = infinity,
1/d = 1/2 (1/5 + 1/infinity) = 1/10 --> d = 10 ft (as expected for the hyperfocal distance)

dc = 5ft, df = 8ft,
1/d = 1/2 (1/5 + 1/8) = 0.162 ft --> d = 6.2 ft (as expected for far distances focus is 1/3 of the way, which would be exactly 6 ft)

dc = 2 inch, df = 2.2 inch
1/d = 1/2 (1/2 + 1/2.2) = 1/0.478 --> d = 2.1 inch (as expected, for macro the focus is the midpoint)

BTW, if you compare various distances are you using the basis of the hyperfocal distance, which for FF is 8x enlargement (w/o crop) and viewed from 13 inches?

Last edited by dms; 06-09-2019 at 09:58 AM.
06-09-2019, 10:07 AM   #3
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QuoteOriginally posted by dms Quote
The proper focus distance is the average of the inverse distances. So if the closest desired distance is dc, and farthest is df, then the optimum d,is: 1/d = 1/2 (1/dc + 1/df).
Yes, if I understand correctly that's focusing at the hyper-focal distance.

---------- Post added 09-06-19 at 19:09 ----------

QuoteOriginally posted by dms Quote
BTW, if you compare various distances are you using the basis of the hyperfocal distance, which for FF is 8x enlargement (w/o crop) and viewed from 13 inches?
Well, I take the DoF calculator which use these criterion as basis to depth of field and hyperfocal calculation. I have to go now, but I'll prepare and post some values as example to clarify my post later.
06-09-2019, 10:32 AM   #4
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QuoteOriginally posted by biz-engineer Quote
Yes, if I understand correctly that's focusing at the hyper-focal distance.
The equation is good for all distances. For hyperfocal distance, it becomes even simpler (since 1/infinity=0), and thus:

d = hyperfocal distance (in this case) = 2 x dc.

06-09-2019, 10:45 AM   #5
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They are somewhat usable with film where proper sharpness does not really exist, except maybe technical pan films.

Focus stacking is the way to go.

I stopped using guesswork methods when proper liveview was available.
06-09-2019, 12:23 PM   #6
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All right. Lets take Pentax K1 with lens at 20mm (e.g D-FA 15-30 @ 20mm).
- Lens: FL 20mm, Aperture f/5.6

- Hyperfocal distance = 8.124 ft

Nearest point in acceptable focus distance vs focus distance

- Focus at 1 ft : near focus = 0.896 ft ; far focus = 1.131 ft
- Focus at 5 ft : near focus = 3.101 ft ; far focus = 12.898 ft
- Focus at 10 ft : near focus = 4.479 ft ; far focus = infinity in theory (but practically the background is not sharp...)
- Focus at 20 ft: near focus = 5.757 ft ; far focus = infinity in theory (but practically the background is not sharp...)
- Focus at 100 ft: near focus = 7.462 ft ; far focus = infinity ; here the focus point distance was multiplied by 500% (20 ft x 5 = 100 ft) but the near focus distance only increased < 30%
- Focus at 1000 ft: near focus = 7.994 ft ; far focus = infinity ; the focus distance was multiplied by 10 (1000% increase) but the near focus distance only increased a little, and now let say at 1000 ft is a mountain the whole mountainairy background area in the image frame is tack sharp and with lost only a few feet of acceptable focus in the foreground.

It is a lot more simple to have the lens focused at infinity, lose a little distance of sharpness in the foreground and have the whole remaining part of the image tack sharp. There is also a video from Thomas Heaton (See minute 9 here:
), and he says that he tried with his camera the hyperfocal distance thing and he found that hyperfocal didn't work for him and focusing at the farther distance in the landscape was giving him the best results.
06-09-2019, 12:35 PM   #7
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I'm with Heaton on this. Infinity or distance focusing generally works best in practice unless you have a very close foreground subject.

Hyperfocal sounds fine in theory but it doesn't take into account the field curvature of most lenses, particularly wide angle lenses used a lot for landscape work.


Try to hyperfocal a landscape scene with the DA 15 for example and the results are a disaster.

I learnt this through trial and error.
06-09-2019, 12:38 PM   #8
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Just focus to infinity and about a meter or so with 15-30 @f/8, load those two frames to focus stacker and be done with it. Or switch to Canon and get 17mm T-SE. Both tactis give superior result.

06-09-2019, 01:16 PM   #9
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Hyperfocal focusing is the theory. Old / MF lenses often have a distance scale, which can be useful for hyper-focal focusing. None of my D-FA lenses have a proper aperture distance scale and I can't set UI option in the K1 to have the lens focus at the right distance. Focus stacking sounds like the best way to go.
06-09-2019, 05:50 PM   #10
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QuoteOriginally posted by biz-engineer Quote
All right. Lets take Pentax K1 with lens at 20mm (e.g D-FA 15-30 @ 20mm).
- Lens: FL 20mm, Aperture f/5.6

- Hyperfocal distance = 8.124 ft

Nearest point in acceptable focus distance vs focus distance

- Focus at 1 ft : near focus = 0.896 ft ; far focus = 1.131 ft
- Focus at 5 ft : near focus = 3.101 ft ; far focus = 12.898 ft
- Focus at 10 ft : near focus = 4.479 ft ; far focus = infinity in theory (but practically the background is not sharp...)
- Focus at 20 ft: near focus = 5.757 ft ; far focus = infinity in theory (but practically the background is not sharp...)
- Focus at 100 ft: near focus = 7.462 ft ; far focus = infinity ; here the focus point distance was multiplied by 500% (20 ft x 5 = 100 ft) but the near focus distance only increased < 30%
- Focus at 1000 ft: near focus = 7.994 ft ; far focus = infinity ; the focus distance was multiplied by 10 (1000% increase) but the near focus distance only increased a little, and now let say at 1000 ft is a mountain the whole mountainairy background area in the image frame is tack sharp and with lost only a few feet of acceptable focus in the foreground.

It is a lot more simple to have the lens focused at infinity, lose a little distance of sharpness in the foreground and have the whole remaining part of the image tack sharp. There is also a video from Thomas Heaton (See minute 9 here: Landscape Photography | Things I Wish I Knew Earlier - YouTube), and he says that he tried with his camera the hyperfocal distance thing and he found that hyperfocal didn't work for him and focusing at the farther distance in the landscape was giving him the best results.
Your results sound like a problem with choice of radius of the CoC (Circle-of-confusion).

Some DoF calculators use a pretty large CoC radius that is defined by sharpness tolerances for viewing of 8x10 prints at a "normal" distance. The hyperfocal and near-focus/far-focus numbers they give don't work for pixel-peeping.
06-09-2019, 06:25 PM   #11
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QuoteOriginally posted by photoptimist Quote
Your results sound like a problem with choice of radius of the CoC (Circle-of-confusion).

Some DoF calculators use a pretty large CoC radius that is defined by sharpness tolerances for viewing of 8x10 prints at a "normal" distance. The hyperfocal and near-focus/far-focus numbers they give don't work for pixel-peeping.
Who prints 8x10’s and views them at ‘normal’ distance any more?
06-09-2019, 06:42 PM - 2 Likes   #12
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QuoteOriginally posted by monochrome Quote
Who prints 8x10’s and views them at ‘normal’ distance any more?
The people playing 45's?
06-09-2019, 08:46 PM   #13
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QuoteOriginally posted by monochrome Quote
Who prints 8x10’s and views them at ‘normal’ distance any more?
1. This does not change the usefulness of the concept of the hyperfocal distance, it just means you can adjust the values for the degree of enlargement you use, or "quick and dirty" simply use the usual hyperfocal distance values but use a smaller aperture by a stop or two. Otherwise one does not have an easily used concept for zone focussing, and notwithstanding the above posts, I think simply using infinity cannot be right if there is nearer stuff of import--if for no other reason we tend to look at the larger (closer) things in a picture to assess sharpness--even if it is not the most important stuff.

2. Actually I make hundreds of prints--usually in the range 7"x11" to 8"x12"--for theatre producer/lighting designer/ costume ... That is pretty much what they expect to see and show. And for me (for FL of 28mm and below) I almost always use the hyperfocal distance--for theatre and outdoors.
06-09-2019, 09:19 PM   #14
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QuoteOriginally posted by photoptimist Quote
The people playing 45's?
I have a couple hundred 45’s and 800 LP’s. My daughters still DJ 45’s for spontaneous “dance parties”.(we are so weird).

I recently purchased a replacement turntable but I had to hack my AVR to connect it.
06-09-2019, 10:09 PM   #15
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QuoteOriginally posted by biz-engineer Quote
Hyperfocal focusing is the theory. Old / MF lenses often have a distance scale, which can be useful for hyper-focal focusing. None of my D-FA lenses have a proper aperture distance scale and I can't set UI option in the K1 to have the lens focus at the right distance. Focus stacking sounds like the best way to go.
Yeah, something like what I was thinking as I started to read this thread. "Modern", more "advanced" lenses for DSLRs lack the basic depth of field scale and often even the distance scale is not included. I don't have a K-1 yet but eventually I will. So, I will make use of all my K and M lenses and never worry about lacking that basic information.
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