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View Full Version : 9-18 mm and hyperfocal distance


Pete_Murrell
15th May 2012, 12:29 PM
Hi there guys.
Does anybody know where I can find (or how I can work out) the hyperfocal distances for the 9-18mm at various f stops? I tried looking at some websites but it seems I need a tool to do it. Does anybody know by chance what the hyperfocal distance is for say f11?

snaarman
15th May 2012, 12:39 PM
http://www.dofmaster.com/dofjs.html maybe? Set the camera type, enter in the numbers, note down the answer..

Pete

Pete_Murrell
15th May 2012, 01:05 PM
Thanks for that mate.
Just a couple of questions. In the fields do I put 9mm (for arguments sake) or put the 35mm equiv. of 18mm in the focal length section?
And by near limit....do they mean everything from .68m and beyond should be in focus?

theMusicMan
15th May 2012, 01:06 PM
I think you just put in 9mm i.e. the actual focal length of your lens. The fact that you enter your camera model in another field suggests the equations take into account any crop factor and/or sensor size.

Bikie John
15th May 2012, 01:30 PM
John MusicMan is right. You choose your camera type and it sets the "Circle of Confusion" which is a measure of how fuzzy the image is allowed to be and still considered in focus. For our 4/3rds (micro or big) sensors it uses a CoC of .015mm, for 35mm it uses the old accepted standard of .03 mm. Then you put in the actual focal length (so 9mm for the wide end, not 18). The small CoC compensates for the fact that using a smaller sensor or film, the image will be enlarged more so any unsharpness on the sensor will be more apparent in the final print or screen image.

Depth of field is not an exact science. These figures for CoC are based on "standard viewing conditions", which I think assume that you will make an approximately 10 by 8 inch print from the whole image and view it at arms' length. If you are going to downsize for the web you could get away with a lot more, if you are going to pixel-peep or make a huge print and hand your viewers a magnifying glass you will have to be more cautious.

Hope this helps ... John

Pete_Murrell
16th May 2012, 02:14 AM
Thanks for your help guys.
So at focal lenght 9mm and f/4. It says the near limit is 3.08 feet and the far limit is infinite. Does that mean if I focus on an object 3.08 feet away, everything from that point on will be in focus?

snaarman
16th May 2012, 07:01 AM
Thanks for your help guys.
So at focal lenght 9mm and f/4. It says the near limit is 3.08 feet and the far limit is infinite. Does that mean if I focus on an object 3.08 feet away, everything from that point on will be in focus?


No, check out the subject distance value on that calculator page as well. It says if you focus on 10 feet, everything from 3.08 feet to infinity will be in focus.

As I doscovered with the 9-18 and the 11-22 before, despite what they say about ultrawides and their huge depth of field, it is still possible to end up with the horizon out of focus if you are not careful!

Pete

Zuiko
16th May 2012, 07:02 AM
John MusicMan is right. You choose your camera type and it sets the "Circle of Confusion" which is a measure of how fuzzy the image is allowed to be and still considered in focus. For our 4/3rds (micro or big) sensors it uses a CoC of .015mm, for 35mm it uses the old accepted standard of .03 mm. Then you put in the actual focal length (so 9mm for the wide end, not 18). The small CoC compensates for the fact that using a smaller sensor or film, the image will be enlarged more so any unsharpness on the sensor will be more apparent in the final print or screen image.

Depth of field is not an exact science. These figures for CoC are based on "standard viewing conditions", which I think assume that you will make an approximately 10 by 8 inch print from the whole image and view it at arms' length. If you are going to downsize for the web you could get away with a lot more, if you are going to pixel-peep or make a huge print and hand your viewers a magnifying glass you will have to be more cautious.

Hope this helps ... John


Spot on, John, that's a great explanation. *chr

Zuiko
16th May 2012, 07:50 AM
No, check out the subject distance value on that calculator page as well. It says if you focus on 10 feet, everything from 3.08 feet to infinity will be in focus.

As I doscovered with the 9-18 and the 11-22 before, despite what they say about ultrawides and their huge depth of field, it is still possible to end up with the horizon out of focus if you are not careful!

Pete

Exactly. *yes

Also we should be aware that the principle of DOF relies on "apparent" or "acceptable" sharpness; whatever aperture is used there is still only one plane of absolute focus. When working at the extremes the near and far points will still have an element of softness, particularly when the image is magnified beyond 10x8 inches, which gradually improves towards the true point of focus. Hyperfocal distance is not a magic wand which renders everything within the near and far limits as pin sharp as the true point of focus.

When I have plenty of DOF to play with I'll set the aperture at least one stop smaller than required by the calculation, for example f8 instead of f5.6. In theory when an extreme DOF is required we could use f22 instead of f16 but then diffraction rears its ugly head and there is a danger that nothing will be as sharp as it could be. Under normal circumstances f11 is the smallest aperture you should use on a 4/3 camera and preferably f8.

For this reason, when working at the extremes you may have to make a choice between forground and infinity for sharpness. If, say, you are using a wide angle lens to photograph a range of distant mountains with a field of wild flowers in the forground, typically the nearest flowers will loom large and dominate the image whilst the mountains appear relatively small. You check the hyperfocal calculations and find that the mountains and nearest flowers are right on the very limits for near and far DOF for f11. The chances are that both the flowers and mountains will not appear acceptably sharp if you make a nice big print. You could use f16 but that risks degrading the whole image which obviously is not good when printing large. So what do you do?

A decision has to be made whether to favour the mountains of the flowers. If you favour the flowers by moving the point of focus a little closer the mountains will, of course, lose definition. But they are a relatively small part of the image playing more of a supporting role to those gorgeous blooms in the forground. When viewing a print the eye will naturally be drawn to those stunning flowers and the viewer probably won't even notice the softness of the background.

Alternatively you may want to creatively exploit the insufficient DOF by allowing the nearest blooms to blur into a soft haze of colour, against which flowers a little further back and of course the mountains appear tack sharp. Out of focus elements in an image can give the illusion that the rest is sharper than it actually is.

It's best to regard hyperfocal distance and depth of field as part of the creative process which allows you choices in pursuit of your vision, rather than just a technical element governed by precise definitions.

cariadus
16th May 2012, 08:26 AM
Interesting discussion. I still wish camera manufacturers would put a hyperfocal setting on digital cameras - it's ridiculous that you have to use a chart to work it out.

Pete_Murrell
16th May 2012, 11:47 PM
I also wish there was a hyperfocal setting.
In saying that it must be said that I appreciate all the time and effort you guys have put into this thread. A big help.
I am new to wide angle photography and all of this is a big help.
I figure if I work out what the hyperfocal point is for 9mm at f/4, if I use that focal distance and step down to f/8 the image should work out. Of course, as with any new lens it will be a matter of trial and error. And for me this is no problem because it's half the fun of photography...learn by doing. And in learn by doing I tend to come up with some interesting shots that work...even if they aren't technically great.
Thanks again guys.

Zuiko
17th May 2012, 01:18 AM
I also wish there was a hyperfocal setting.
In saying that it must be said that I appreciate all the time and effort you guys have put into this thread. A big help.
I am new to wide angle photography and all of this is a big help.
I figure if I work out what the hyperfocal point is for 9mm at f/4, if I use that focal distance and step down to f/8 the image should work out. Of course, as with any new lens it will be a matter of trial and error. And for me this is no problem because it's half the fun of photography...learn by doing. And in learn by doing I tend to come up with some interesting shots that work...even if they aren't technically great.
Thanks again guys.

You're right, Pete, doing is the best way of learning. One of the biggest advantages of digital over film is that it costs nothing to try new things or photograph the same scene in a variety of different ways. This is just as well because many modern lenses, particlarly zooms, don't even have a distance scale. This means you have to judge by eye and focus on the point which you guess is the correct distance. This is obviously prone to error and far from ideal but I get around that by taking a series of shots with differing points of focus to hedge my bets when DOF is critical. Essentially I am focus bracketing. When the focus is not quite so critical I do as you suggest and calculate for f4 but set the lens to f8. That allows for a wide margin of error!

maccabeej
17th May 2012, 11:49 AM
If you have a smart phone DOFMaster have an app.
Jim

ChrisW
17th May 2012, 02:38 PM
This is the D.o.F. table I have taped on the back of my E5. Left column is zoom, top row is aperture and the figures below are distances in metres.

The figures were calculated on http://www.dofmaster.com/dofjs.html

Hopefully they are correct :eek:

http://e-group.uk.net/gallery/data/660/Hyperfocal_Distnaces_and_Mysets.jpg (http://e-group.uk.net/gallery/showphoto.php/photo/38348)

Stewart G
17th May 2012, 02:47 PM
Another good (free) android app for this (and lots of other photo stuff) is "Phototools."