# DOF, Infinity focus and Hyperfocal distance



## ray5 (Dec 6, 2014)

Hi,
Can someone please explain how these work? I understand Depth of field but not the others. What is the theory behind them and how to use them practically? And then any App for the iPhone that is easy to use? Thanks,
Ray


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## surapon (Dec 7, 2014)

ray5 said:


> Hi,
> Can someone please explain how these work? I understand Depth of field but not the others. What is the theory behind them and how to use them practically? And then any App for the iPhone that is easy to use? Thanks,
> Ray




Dear Friend, Mr. ray5.
Sorry, I am not the expert in these Technical Terms, But There are so many Teachers and Friends , Who will explain to you and Me.
But, I have use this attached Link for long, long time, And Help me to understand and the How to. :

http://www.dofmaster.com/dofjs.html

Enjoy.
Surapon


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## privatebydesign (Dec 7, 2014)

Infinity focus is the theory that if you want the optimal image sharpness throughout your frame, like a landscape, then ignore hyperfocal focusing which is the 'commonly adopted' way to do that and just focus at infinity. This idea has a very important proponent, Harold Merklinger, who has done some very good work on the maths behing focusing, dof, tilting and shifting.

Hyperfocal focusing relies on the fact that nothing is infinitely sharp, everything either side of the infinitely narrow plane of focus is just a bit less sharp than the bit closer, this sounds bad until you realise that DOF figures are all based on human acuity, the sharpness levels within the DOF are supposed to be so small that the human eye can't tell that they are not sharp. Therefore if your dof at 20ft is from 10 ft to infinity then you get optimal image sharpness throughout the image if you focus at 20ft.

Hyperfocal breaks down a bit on several levels, the figures given in dof meters are not necessarily accurate enough, the output size and viewing distance impact the dof and that is rarely known at the time of capture, and many people have better than average eyesight.

I believe infinity focus gives better sharpness throughout the image, or focusing two stops narrower than a hyperfocal distance would dictate, ie, if you are shooting at f11 use the focus distance for f5.6, this holds the infinity nice and sharp and gets the foreground as good as it will get. Unless you have foreground interest and you want to hold a sharp infinity, then you have to choose, or blend multiple images, or use a lens that tilts.


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## Ryan85 (Dec 7, 2014)

I'm not great at explaining this but if you do a google search you'll find a bunch of info. If your lens has a depth of field scale on top of it, lots of prime lenses have them, some zooms do. Anyway if you use your manual focus turn the focus ring while looking at the scale on the lens turn it until you see the sideways 8 looking thing. If you set that between the lines on your scale then in theory everything from whatever that scale says like 8m to infinity should be in focus. That sideways 8 thing is the symbol for infantry. Hyper focal distance is kinda the same thing. Use that scale move the manual focus ring until it's at the distance you want. It'll have lines so you can set the hyperfocal distance for what's in focus and what's not. Like everything from 3m to 8m will be in focus and everything closer than 3m or over 8m won't be as/sharp. It's handy for some things. Like if your shooting birds in flight or sports or any fast moving subject you set the focal distance to were you think the shot will be so when the action happens your ready to shoot and don't need to focus since your already focused there. Also handy for shooting night photography. If it's pitch black outside and you're shooting star trails set that lens to the infinity symbol and it hose stars should be in focus. Some lens scales are more accurate than others so play with it and try it out. I hope that helps you..... if I explained it wrong hopefully othere will correct me.


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## candc (Dec 7, 2014)

well you know how dof works for different apertures. older lenses like this 15mm fisheye have the scale on the lens, there are charts for ones that don't. the hyperfocal distance for a lens at a given aperture is supposed to be the the distance you can focus at where everything from there to infinity will seem in focus. so in the picture here, if i was using f/8 i would set the infinity symbol at 8 and you can see the hyperfocal distance is just less than 1 meter. the idea is that there will be more of the foreground in focus than if you set the lens to infinity for landscapes.


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## Ryan85 (Dec 7, 2014)

candc said:


> well you know how dof works for different apertures. older lenses like this 15mm fisheye have the scale on the lens, there are charts for ones that don't. the hyperfocal distance for a lens at a given aperture is supposed to be the the distance you can focus at where everything from there to infinity will seem in focus. so in the picture here, if i was using f/8 i would set the infinity symbol at 8 and you can see the hyperfocal distance is just less than 1 meter. the idea is that there will be more of the foreground in focus than if you set the lens to infinity for landscapes.




Good example


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## Mt Spokane Photography (Dec 7, 2014)

I would not rely on hyperfocal distance too much. With digital cameras and the ability to view images on a computer screen, you will find that the focus is really not as good as you'd like. It was fine in the days of film where few photographers had a microscope to view the sharpness of detail on the film (Some definitely did). 

A smaller aperture will increase the apparent depth of field, but its a trade off, because tiny apertures like f/16 , f/22 and smaller also reduce the sharpness of a image. Its still better to use a f/16 aperture than f/11 and relying on the hyper focal calculators.

The best way to learn what is acceptable to you is to try different apertures for a landscape photo, try f/5.6, f/8, f/11, f/16, and f/22 to see the changes in depth of field and sharpness.


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## Ryan85 (Dec 7, 2014)

Mt Spokane Photography said:


> I would not rely on hyperfocal distance too much. With digital cameras and the ability to view images on a computer screen, you will find that the focus is really not as good as you'd like. It was fine in the days of film where few photographers had a microscope to view the sharpness of detail on the film (Some definitely did).
> 
> A smaller aperture will increase the apparent depth of field, but its a trade off, because tiny apertures like f/16 , f/22 and smaller also reduce the sharpness of a image. Its still better to use a f/16 aperture than f/11 and relying on the hyper focal calculators.
> 
> The best way to learn what is acceptable to you is to try different apertures for a landscape photo, try f/5.6, f/8, f/11, f/16, and f/22 to see the changes in depth of field and sharpness.



+1....your right the focus isn't great and I wouldn't relie on it but it's a good starting place especially for night shots imo but like Mt. Spokane photography said test it. Some lenses scales are off a little.


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## e17paul (Dec 7, 2014)

TrueDoF-Intro Depth of Field Calculator by George Douvos
https://appsto.re/gb/NIh-E.i Is a convenient tool on iPhone.


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## Marsu42 (Dec 7, 2014)

e17paul said:


> TrueDoF-Intro Depth of Field Calculator by George Douvos
> https://appsto.re/gb/NIh-E.i Is a convenient tool on iPhone.



Magic Lantern tells you the hf in the camera gui - and imho it's still a nice information, even as discussed it's not reliable in the digital age and can only used as a guideline.


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## PavelR (Dec 7, 2014)

I know only the one page describing DOF deeply: http://toothwalker.org/optics/dof.html


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## msm (Dec 7, 2014)

I don't bother with hyperfocal distance or infinity focus at all personally.

Hyperfocal distance is based on a viewer with a specific eye sight viewing an image at a specific print size at a given distance. If a viewer has better eye sight than the assumption or if the viewer moves up closer to view a detail, then the theory no longer applies.

In real life there are also another matter that complicate the matter, which the theory takes does not take into account: curvature of field. All lenses have it and in particular on very wide angles this makes it harder to get focus all the way from center to the corner of the frame.

And also at narrow apertures diffraction kicks in. In my opinion the best thing to do is to use live view with focus loupe to seek the best balance between aperture, foreground, background, middle frame and corners. Practical results always beat oversimplified theories.


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## ray5 (Dec 7, 2014)

Hi,
Thanks for all the replies. Here is where it started. I had posted an image, given below. It's acceptable but when zoomed in, not tack sharp or at least ALL of it which this image demands. Live view won't work(low light, long exposure etc) with Auto Focus but only with MF in this light. I need to improve my technique. Here is the link to the image and the picture information. I am going there to take the shot again.



http://www.canonrumors.com/forum/index.php?action=dlattach;topic=22558.0;attach=120182;image
ISO 200, F14, 38mm and 20 sec shot on tripod with cable release straight out of camera, no post at all.

What I learn:
Switch to MF with live view
Perhaps F8-11 rather than F14 or higher
Try and get everything in focus using infinity focus

What I have changed:
- Lens has been upgraded to version II of the 24-70 F/2.8
- Tripod is much sturdier with RRS

So,
to do it right am I doing:
- Composing it the way I like
-Turning the lens to MF and then turn the focus ring to infinity?
And I should have quite a wide DOF and sharpness I desire?
I probably sound naive, sorry. Thanks for your critique and help.
Ray


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## lilmsmaggie (Dec 8, 2014)

Another thing to consider is that most lenses designed for auto-focus, focus beyond infinity. 

Focusing using hyperfocal distance, or focusing at infinity is best done with a manual lens.

Check out the DOFmaster link that Surapon provided and you might want to read this:

http://www.cambridgeincolour.com/tutorials/hyperfocal-distance.htm


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## ray5 (Dec 8, 2014)

lilmsmaggie said:


> Another thing to consider is that most lenses designed for auto-focus, focus beyond infinity.
> 
> Focusing using hyperfocal distance, or focusing at infinity is best done with a manual lens.
> 
> ...



Thanks. I read both. I am not clear but infinity focus and Hyperfocal distance seem to be two different things. Using the link and the calculator:

Full Frame sensor
F8, Focal length: 40mm
Focus distance: 500m
It calculates to 6.17m as nearest acceptable sharpness and infinity as the farthest.

Now,
The focus distance is probably hard to estimate for a landscape shot. So am I not focussing at roughly 6.17 m to get this large DOF or am I focussing at 500m to get that? And what if my focus distance of 500m is totally off?
Ray


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## lilmsmaggie (Dec 9, 2014)

Try this link instead for an explanation, don't go straight to the calculator:

http://www.dofmaster.com/hyperfocal.html -- the illustrations should be self-explanatory. If you have a manual focus lens, it will be easier for you to see on the lens barrel than someone trying to explain. Borrow one if you don't have one and play around with it while you're reading the section on hyperfocal distance.

Basically, the calculation below is telling you that everything from 6.17m (the closest the lens will focus at that setting) to Infinity will be in acceptable focus (hyperfocal distance).

Infinity focus basically is the focal point at which an object is brought into focus an infinite distance away. In your example below, you're focusing on an object 500m away. Beyond which is infinity. The infinity mark looks like a L turned on its side. For Canon lenses, the short end of that mark is infinity 

l___

/\
l infinity




BTW - hyperfocal distance focusing is used by many landscape photographers. Hope that helps.





ray5 said:


> lilmsmaggie said:
> 
> 
> > Another thing to consider is that most lenses designed for auto-focus, focus beyond infinity.
> ...


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## privatebydesign (Dec 22, 2014)

ray5 said:


> lilmsmaggie said:
> 
> 
> > Another thing to consider is that most lenses designed for auto-focus, focus beyond infinity.
> ...



Ray,

What is it about my first answer you don't understand? I explain the difference between the two adn where to set your point of focus for hyperfocal focusing.


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