Depth of field - Hyperfocal - landscapes

DorsetDude

DorsetDude

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Hi

Posted this in the wrong forum initially, I'll try in here.

Ive got an iPhone app that calculates Hyperfocal distance and depth of field for various aperture and focal lengths.

So Ive set 14mm and f8 to see what the hyperfocal is - 1.29 metres (also set crop factor to 1.6).
It is also asking me for distance to object. Why?
Surely I just focus at the hyperfocal and my "object" is everything from half that to infinity?
I dont understand why its asking me for this distance to object. Can anyone explain? Do I just ignore the 'distance to object' for landscapes?

Thanks
 
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The app is presumably a depth of field calculator that also tells you hyperfocal distance for the aperarture and focal length. The depth of field (far limit and near limit) that the app gives you is based on the distance to the object (ie the distance you are actually focussing at). It also tells you what the hyperfocal distance will be for that aperature and focal length. The hyperfocal distance doesn't change with the distance you are focussing at, but the DoF will.

If you set the distance to object equal to the hyperfocal distance, in the app, (so 1.30 m near as dammit) the depth of field is given as infinite (well, maximal).
 
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Eh??

All you need from a hypercfocal calculator is your focus distance and it;d be nice to know the nearpoint too, but tbh if you have a scale on the lens you don't need an app and if you don't have a scale you can't set the hyperfocal anyway? :shrug:

Ta da .. hyperfocal set for F16 on 50mm lens (and FF), everything from 2.5m to infinity is in focus, focus point is approx 5m.

P1000567.jpg
 
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Alan Clogwyn said:
All you need from a hypercfocal calculator is your focus distance and it;d be nice to know the nearpoint too, but tbh if you have a scale on the lens you don't need an app and if you don't have a scale you can't set the hyperfocal anyway? :shrug:
Click to expand...

Eh??

Most zooms dont have a scale(I believe. None of my 3 do anyway). To set the hyperfocal I would focus on an object at that distance (or near as dammit). The app gives me the HF distance dependent on my zoom setting.

I was confused by the distance to object stuff but realise now I just ignore that for hyperfocal focussing.

EDIT: just used the app for your lens and gives 5.39m for hyperfocal, cool.
 
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An advantage of not focusing on infinity and calculating an aperture based on near to infinity but instead choosing a distance to match the scene is that you can use a wider aperture. Why use f22 if f8 gives reasonable focus throughout the frame?

I'm not a massive fan of hyperfocal and DoF tables and I think that people tend to take them to extremes, and far too many decimal places :D

An alternative to 3 decimal place DoF tables is ...

http://www.northlight-images.co.uk/article_pages/hyperfocal_distance.html

... or create a more natural look by using a wider aperture and letting sharpness drop with far objects in the frame.
 
DorsetDude said:
I was confused by the distance to object stuff but realise now I just ignore that for hyperfocal focussing.
Click to expand...

No, you shouldn't ignore distance. For example, if your scene only extends to "x"m why set your aperture based on infinity?
 
Dude you may as well just let it AF wherever the hell it wants in that case and use a small aperture, unless you plan on carrying a set of surveying instruments with you as well :p

Hyperfocal settings are meant for use with manual focussing. They're no real use a lot of modern cameras which make it all but impossible to set a hyperfocal scale.

Side Note: why th hell hasn't anyone devised a camera that can do automatic hyperfocal focussing? It wouldn't reqire anything extra hardware wise, just a menu option to select it, select aperture, halfpress/back buttn to set focus = job done, yet no one does it* :shrug:

*That I'm aware of and no one else has pointed out this mode to me before....
 
woof woof said:
No, you shouldn't ignore distance. For example, if your scene only extends to "x"m why set your aperture based on infinity?
Click to expand...
Well, I guess, but most of my landscapes are going to have horizons, clouds in view etc which are effectively infinity.
I suppose in a woodland or something I could change it.
 
Yup.

I suppose one of my main points (apart from don't take hyperfocal tables as the word of God) is that you should use the widest aperture suitable for the scene and avoid using the most narrow apertures unless you make a conscious decision to.
 
woof woof said:
Yup.

I suppose one of my main points (apart from don't take hyperfocal tables as the word of God) is that you should use the widest aperture suitable for the scene and avoid using the most narrow apertures unless you make a conscious decision to.
Click to expand...

Indeed and this is why I have gone for a Hyperfocal app. Where before I would set f11 or f16 and "hope for the best" I may now find I can go to f8 and still get sharp shots. And if I have got extremely near items in the foreground I can now work out how to get them sharp. Either by stopping down or moving the camera back a bit. Probably.
 
Alan Clogwyn said:
Eh??

All you need from a hypercfocal calculator is your focus distance and it;d be nice to know the nearpoint too, but tbh if you have a scale on the lens you don't need an app and if you don't have a scale you can't set the hyperfocal anyway? :shrug:

Ta da .. hyperfocal set for F16 on 50mm lens (and FF), everything from 2.5m to infinity is in focus, focus point is approx 5m.

P1000567.jpg
Click to expand...

The scale on the lens is only a different form of app, or you can use a table. Either way, you need to be able to estimate short distances, but you don't need to focus manually. And handy though lens scales are, they are no good if you switch formats, as we do these days. Those settings on the Pentax lens, if fitted to a 1.6x crop camera would give completely different DoF from 3.2-14.4m. On 1.5x crop it would be different again, and on 4/3rds yet further adrift.

Easy way to set hyperfocal distance, decide on the nearest object you want sharp, estimate that distance by eye (it's going to be close, so not hard) then double that distance exactly and AF on it using the centre point.

That's your HFD set, so find that distance on your table or app or whatever, and set the appropriate f/number.
 
DorsetDude said:
Indeed and this is why I have gone for a Hyperfocal app. Where before I would set f11 or f16 and "hope for the best" I may now find I can go to f8 and still get sharp shots...
Click to expand...

Good stuff.
 
HoppyUK said:
Easy way to set hyperfocal distance, decide on the nearest object you want sharp, estimate that distance by eye (it's going to be close, so not hard) then double that distance exactly and AF on it using the centre point.

That's your HFD set, so find that distance on your table or app or whatever, and set the appropriate f/number.
Click to expand...

Sounds good that, cheers! :thumbs:
 
DorsetDude said:
Sounds good that, cheers! :thumbs:
Click to expand...

:)

It's really easy. All you need is a few numbers on a sticker inside your lens cap - just key distances, focal lengths and apertures. You can guess the inbetween settings easily enough.

You don't need a whole table because in practice HFD focusing is only practical with wideish angle lenses. I posted an example in another thread on this only a few days ago, here http://www.talkphotography.co.uk/forums/showthread.php?t=384043
 
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