Focus Method, expalantion needed please

[rickp1]

I keep reading about Hyper Focal Distance and having everything in focus after certain distances.

Can someone explain to me how this works or how to do it. I'm heading to yellowstone next month and I want to make sure my landscape shots are in focus and I maximize clarity. I'm not sure that using the AF points on my 7D will work the best if taking a picture of a mountain range 15 miles away from across a lake.

I've also installed a hyper focal distance calculator in my ipod touch but I'm not sure I get how to use it.

Also, i'm reading Bryan Peterson's book "Understanding Exposure" and he makes reference to the Distance Scale focusing method, is that the same as using the hyper focal distance method?

Thank you.
R.

[Elmo]

HFD is basically setting the focus to a distance (F-stop determined) so that everything from infinaty back to a certain point will be in "Acceptable" focus. This is due to the Depth-of-field as determined by the f-stop. So for this type of HFD The far end of the DOF is infinatity. Another application is to determine the actual near and far distances one wants in acceptable focus adjust the f-stop to achieve this DOF and then set the focus to HFD to set the focused area to the right distance. Note the HFD for the first type and the second type will be different.

Confused more??

PS setting focus distance to 1/3 the distance into the desired focus range is a good starting place.

[RichardTaylor]

In addition to Elmo's post
Just keep in mind there will be only one distance that will be "super sharp". That is the distance you focus on. Other distances may be acceptably sharp.

What is acceptable? It depends on the size of the image your are viewing, how far away you are viewing it from, and the sensor size, the focal length, the distance to subject and the aperture. It is called "circle of confusion" and I will not go there.

Some software may only ask for for the sensor size, aperture and focal length.

For Hyperfocal distance you don't gave to worry about the distance to the subject.
Example:
Online Depth of Field Calculator
(Edited) to correct my error
Your 17-55 lens on a 7D
17mm @ F2.8 = 17.7 feet
Which means everything from (17.7)/2 feet to infinity will be acceptably sharpie approx 9 feet.

17mm & F8 = (6.17) /2 feet
17mm @ F22 = (2.26)/2 feet

28mm & F2.8 = 48/2 feet
28mm @ F8 = 17/2 feet
28mm @ F22 = 6/2 feet

55 mm @ F2.8 ~185/2 feet
55mm @ F8 = 65/2 feet
55mm @ F16 ~ 33/2 feet
55mm @ F22 =(23.3)/2 feet.

In practice, for landscapes, it is not so hard.

If I am using auto focus.
(1) I always set my focus point to centre focus point only
(That means the camera is not taking control of where it will focus, I am)
(2) I set my auto focus mode to single shot.
That allows me to focus & recompose.
I usually just focus on the object I want to be sharpest and will be shooting from F11-F22 to give me a lot of DOF.
I usually don't think about hyperfocal distance.
I don't carry a calculator or chart with me,

My pics usually end up as 10x8" (A4) or on the web.
Keeping mind other constrain like diffraction, at small apertures may come into play if you are to be going to make very large prints.

Here are some real world examples.
(1) I would have focussed on the ElK.

Camera: Canon EOS 40D
Exposure: 0.004 sec (1/250)
Aperture: f/16
Focal Length: 70 mm
The hyperfocal distance would have been ~ 50'

(2)

Camera: Canon EOS 40D
Exposure: 0.008 sec (1/125)
Aperture: f/11
Focal Length: 70 mm
ISO Speed: 800
Hyperfocal distance would have been 75 feet.

(3) I would have been focussing on the squirrel or the people.

Camera: Canon EOS 5D
Exposure: 0.003 sec (1/320)
Aperture: f/20
Focal Length: 32 mm
The hyperfocal distance would have been 6'

(4) Here I would have focussed on the birds eye.

Camera: Canon EOS 40D
Exposure: 0.005 sec (1/200)
Aperture: f/10.0
Focal Length: 12 mm
The Hyperfocal distance is less than 2'

[thecharmed01]

@RT, what did you focus on in the second shot?

[RichardTaylor]

Pic was hand held and I think I would have focussed on the distant shore, around the rocks.

[OsmosisStudios]

Richard: thanks for posting that link, however your post isnt quite correct.

In your example, you give 17mm @ f/2.8 and claim that everything from 17.7 ft to infinity would be in focus. This is wrong. 17.7 ft is the distance at which you should set focus to achieve hyperfocal depth of field and, as such, the "acceptable sharp" region would be anywhere from 0.5*17.7 (or 8.85ft) to infinity.

The hyperfocal calculator gives you the hyperfocal distance, which is the distance at which to focus. That being said, your method works very well and is likely just as good (or unnoticeably just as good) as hyperfocal distance in 90% of applications.

[rickp1]

Osmosis,
I was going to ask the point that you mentioned. From what I read, what is in focus is from half the distance of the HFD to infinity, not exactly at the hyper focal distance, is that correct?

Also, Richard, for the second image you said you focused on the rocks. Since you didn't have a near object to focus on, is there a time you would just use the HFD calculator and just set your lens to the numbers it gives you instead of focusing on something so far away? I hope my question makes sense.
What i was planning to do in situations that I don't have something to focus on close by was to use the HFD calculator in my ipod then configure the lens to those numbers.

And last, can you give the ISO's you shot? The reason I ask is in picture number 2 why did you use ISO 800, what it to bring up shutter speed due to shooting hand held?? Otherwise what ISO's would you use with a tripod?

Thanks
R.

[RichardTaylor]

My apologies for the error.

@ rickp1
Osmosis is correct.

Yes you could use the the calculator and shoot at what is says.
However you may be estimating the distance as not all lenses have distance markings on them. The Canon 70-300 IS F4.5-F5.6 I was using on the 40D doesn't. Your 17-55 does.

When shooting static subjects hand held, especially with a long lens, my biggest concern is camera movement even with an IS lens.
I may be shooting at anything from a 35mm equivalent of ~135mm to 450mm so I will keep my shutter speed fairly high. I don't have any problems shooting at relatively high ISO. The indicated exposure without any exposure compensation was 1/125 @ F8 at ISO 800 so I was pushing it a bit anyway

A couple of external factors also can apply
The lighting conditions don't stay like this for very long (the sun was gone) so it was just a matter seeing the scene whilst driving, jumping out of the car, walking around to get a reasonable composition, shooting, checking the histogram and for "blinkies", dialing in some exposure compensation if needed and re-shoot both in landscape an portrait modes. Also I was on vacation with my wife who is not a fanatical photographer and can sometimes become impatient!
If you are looking at the EXIF data don't take any notice of the date/time as I forgot to correct the camera after the long flights.

The other thing is I always shoot RAW so on a long vacation (this was 6 weeks) I don't really shoot a lot of variations on the same subject..

(1) Here is another example (3 frames earlier) from nearby.
I probably focussed on the closest tree line,

Camera: Canon EOS 40D
Exposure: 0.008 sec (1/125)
Aperture: f/8
Focal Length: 70 mm
ISO Speed: 800
Exposure Bias: 0 EV

(2) Another example from our vacation. Here I wanted to show the grass against the backdrop of the mountains. I also wanted the grass to be as sharp as possible so that is what I focussed on. In hindsight I could have focussed past the grass to get the mountain more in focus and the grass just not quite so sharp.

Camera: Canon EOS 5D
Exposure: 0.013 sec (1/80)
Aperture: f/20 (to give me a lot of DOF)
Focal Length: 60 mm
ISO Speed: 200
Exposure Bias: 0 EV
IS (VR) would have been on.

I mentioned in a previous post that I don't go on vacation with a tripod where there are a lot of flights. If I was travelling by myself for the main purpose of photography I probalby would)

If I am close to home and have a lot more time, and shooting alone, then I will use a tripod, remote release etc, especially in low light etc. I will usually shoot at the lowest native ISO.

Some examples.
(3) At a local business park. Manual focus & exposure.
I would have focussed on the building.

Camera: Canon EOS 5D
Exposure: 8
Aperture: f/11.0
Focal Length: 28 mm
ISO Speed: 100
Exposure Bias: 0 EV

(4) About a 40min drive from home (but not in peak hour)
Aperture priority, Auto exposure bracket was on as I was shooting for HDR but didn't need it). Manual focus on the bridge lights.

Camera: Canon EOS 5D
Exposure: 3.2
Aperture: f/8.0
Focal Length: 45 mm
ISO Speed: 200 (I can't remember why I didn't shoot at ISO 100)
Exposure Bias: 0 EV

These pics are best viewed at full size. Just clicking on them will take you to the Flickr page.

[wildbird]

One more correction, its an Elk, not a Moose