AF-H: A New Focusing Mode for Hyperfocal Distance

In his first article for PhotographyBLOG, Zoltan Arva-Toth takes the bold step of proposing an entirely new auto-focus mode for digital cameras…

Update 1: As this has created a lot of interest, we’ll be contacting the camera manufacturers soon to ask for their input.
Update 2: Kodak, Carl Zeiss, Olympus and DxO Labs have now provided their feedback - see the end of the article.

It is no secret to anyone with a basic knowledge of photography that most modern cameras offer two main focusing modes, manual focus (MF) and autofocus (AF). Autofocus may come in several flavours, including AF-S (called one-shot AF by Canon) for stationary subjects, AF-C (AI Servo) for moving ones – especially useful if your subject is moving toward or away from you – and an intelligent AF-A (AI Focus) mode, which detects if the subject is in motion or not, and acts accordingly.

In manual focus mode, one of the things you can do is set the lens to the hyperfocal distance, which will depend on the actual focal length of the lens and the f-stop you pick. At this setting, everything between infinity and the near limit of the depth of field pertaining to the hyperfocal distance will be in focus. This comes in very handy when you strive to attain the greatest possible depth of field at a given aperture setting. With dedicated manual-focus lenses, this is easily done, for these lenses tend to have a proper distance scale complete with depth-of-field marks. Once you have decided on the f-stop you want to use, you consult the DoF marks belonging to this f-stop and turn the focus ring until the right mark is at the infinity sign. If your lens has a distance scale but no DoF marks, things get a little more complicated, as you have to either calculate or look up the hyperfocal distance for the given focal length and f-stop. But it’s still manageable.

The real problem comes when you have a lens with no distance scale. This, unfortunately, applies to most modern autofocus lenses, i.e. the ones you are most likely to use. In fact, it’s hard to set most AF lenses to the hyperfocal distance regardless of whether they have a distance scale or not, because the manual focus ring tends to have a lot less „travel” between the close-focus point and infinity than on dedicated MF lenses. I have a lens on which there are literally just a couple of millimetres between the 1m mark and infinity. No matter if you know the hyperfocal distance or not, you cannot accurately set it, which can be very frustrating at times.

But hey, aren’t we now living in the 21st century? These new lenses all communicate with the camera body. They transmit focal length and distance information, while the body tells them about the working aperture chosen either by the photographer or the camera’s electronics. So everything that is needed to calculate the hyperfocal distance is at the CPU’s disposal, as is the AF motor that can propel the lens into the specific setting.

Therefore I can see no obstacle to the inclusion of a new autofocus mode, in which the camera would set the hyperfocal distance on the lens, based upon the f-stop and the lens’ focal length (current focal length for zooms). This mode could be called HF or AF-H, and be accessible via the same dial or menu as the current MF, AF-S, AF-C and AF-A modes. The hyperfocal distance could be calculated and set by the camera either every time the aperture and/or the focal length changes, or upon a half-press of the shutter release button. The former may prove a bit power-hungry and irritating in practice, but would also ready the camera for shooting well in advance of releasing the shutter, so I would make this customisable.

Of course, this mode would mostly make sense when shooting wide to normal lenses, not telephotos. But with those lenses, it would make our lives a lot easier. This mode would not have to be limited to SLR cameras. It could be included in compacts too. In fact, it could greatly improve the responsiveness of digital compacts, provided it is implemented in the former way, thus bypassing the two-stage shutter release routine. This focusing mode could transform any sluggish compact into a highly responsive street photography tool, for instance. Sure, you’d need to mind your backgrounds, because they would also be sharply rendered, but that seems like a small compromise for a potentially major improvement in operating speed.

If you like this idea, express your support for it in the Comments section below.

What the manufacturers have to say...

“1° Computing the hyperfocal distance from the aperture and the focal distance is very easy indeed. Since the lens can communicate with the camera body, it would be very simple to automatically set the focus to the hyperfocal distance. This is only a hardware problem. Actually, an old camera as the Canon EOS 850 had a “depth of field mode” where it was possible to specify the furthest and closest point at focus, and the camera determined the aperture. This is quite the same problem, viewed from a different angle.

2° A software solution is not a well posed problem, since we cannot determine the object distance from a single shot and cannot change the focusing distance adequately. In a further future, we can think of having different types of lenses that could provide an estimate of the distance (see for instance the work done at Stanford University, see for instance http://youtube.com/watch?v=9H7yx31yslM ). In this case, it is possible to change the focus a posteriori. In a short term, DxO Labs also integrates its technology in embedded systems and also controls the autofocus, and the answer is then in 1° again.

DxO Labs”

“Thanks for the information. Yes, the AF-H autofocus mode might be an interesting feature for AF (D)SLR-cameras.
Because we do not offer any AF camera model and most of our current lenses are of MF type (except Sony ZA lenses), we cannot comment the technical feasibility in future products.
This is definitively a subject for camera developers and manufacturers, e.g. our partner Sony.

Best Regards

Bertram Hönlinger - Carl Zeiss”

“At Kodak, we don’t comment on specific future development. Of course, we’re always open to new ideas and will continue to listen to our users to help provide guidance on which features are most compelling and interesting to them. To the extent this feature helps users to easily take better pictures it is interesting, but we can’t comment on whether we would look to implement it without more user insight and feedback.

Kodak”

“No comment. Many companies may be working on this kind of approach but they would never talk about it or comment just in case there is a conflict of influence.

Olympus”

Published: Thursday, March 13, 2008

Reader Comments

1. One more reason for companies to release the firmware of cameras to open source!!!
   I militate for years in this direction !
   The first manufacturer who will act in thiw wise mode will gain the market as IBM does with PC against MACs.

   Renato at 12:24pm on Sunday, February 24, 2008

2. Very interesting, but personnaly, I never use Hyperfocal ...

   photo at 12:54pm on Sunday, February 24, 2008

3. What a brilliant idea. I spent all of last Sunday using the non-linear manual focus on my Nikon 18-200 at the 18mm end trying to hit the hyperfocal distance. It was so hit and miss that I gave up and went back to use AF onm an object a bit further away that the desired distance.

   martin at 01:33pm on Sunday, February 24, 2008

4. The latest version of CHDK firmware for Canon compacts (allbest build 34) has the ability to display and set the hyperfocal distance at any zoom/aperture combination. I used to use hyperfocal 28mm lens quite a lot, so I'll see how useful this proves to be on my A710.

   James at 02:18pm on Sunday, February 24, 2008

5. so you think pc's are open source and apple systems are not? how peculiar. http://www.apple.com/opensource/
   
   the automated hyperfocal idea is interesting. hyperfocal is linked to a particular magnification factor, it might take some user customization , but it could be useful.

   chinggatchgook at 02:49pm on Sunday, February 24, 2008

6. An excellent idea, here are a could more thoughts:
   
   1. this can also be used to good effect on distant telephoto shots where you are "shooting through" obstructions (such as a wire fence, some foreground branches or the bars in a cage at the zoo) which you do not want to attract the focus.
   
   2. An additional feature that could be used with this would be for the camera's normal autofocus system to pick its typical targets and identify those of them that will be in the hyperfocus zone with circle outlines and those of them that will be out of focus (because they are too close) with X's. This way the photographer can see if the hyperfocus coverage includes the significant features, and if not he can either increase the f-stop, reduce the zoom or switch over to one of the conventional modes.
   
   3. Another variation on this is for you to enter the maximum and minimum focus distances and then allow the camera to control the f-stop to meet your requirements as you zoom the lens. In this mode the camera would control the exposure by adjusting the shutter speed. The point of this is for fast point and shoot candid work (say high school year book photography) as it eliminates the shutter lag due to focusing.

   Stephen Vermeulen at 03:34pm on Sunday, February 24, 2008

7. On my EOS 20D there is a setting that sets the focus to be sharp in the range of an array of autofocus points, visible in the viewfinder. It works well, but you need to watch which sensor points are registering. I do agree it would be nice to have more control of depth of field if your lens doesn't have distance marks.

   Gary Allegretta at 03:57pm on Sunday, February 24, 2008

8. chinggatchgook, my comment was about ancient times of personal computers, when IBM released the schemes and source of BIOS to (asian) third party hardware manufactureres, allowing them to generate the wave called "IBM PC compatible".
   This was the key of PC success, because at that times Apple kept closed all the hardware specs and there was no third party card extension on the market, everything comes from the Apple factories at the Apple price.
   Is no surprise that the recent success of Apple if based mainly on the fact they decided to switch to a Linux based OS. This is a very recent move, in the begining such thing wasn't possible for nobody, to write software for Macintosh platform without having (costly) agreements with Apple.

   Renato at 04:04pm on Sunday, February 24, 2008

9. Not to suborn this thread, Renato, but you have several odd inaccuracies in your comments.
   
   - IBM only licensed the BIOS and operating system ... they never actually owned it. So these crude and rudimentary bits at that time were very easy for anyone else to gain access to. The PC was pre-dated by the Apple II and contemporary with it until 1986 ... there was at least as much information available about the Apple II OS and innards as there was for the PC.
   
   - The Macintosh operating system and hardware was intentionally kept closed to standardize and simplify the user experience in an elegant fashion. Microsoft (not IBM) couldn't go this way as they never changed nor updated the BIOS. That archaism is still deeply entwined in the latest Vista release.
   
   - Open Source didn't exist then.
   
   - Apple only briefly licensed their OS and it was a financial disaster for the company, contributory to their near-demise in the mid-1990s.
   
   - Mac OS X is not based on Linux. It is based on UNIX (the Carnegie Mellon MACH kernel and FreeBSD). Linux has a different kernel entirely (ELF).
   
   - Apple ships a complete, professional development system with every machine at no additional cost. Moreover, it has never cost anyone a penny to develop software for Mac OS, any generation, in terms of needing "costly agreements with Apple" ... anyone, at any time, could get a development environment, build and sell their software.
   
   - The vast majority of application software solutions that earn Apple hardware sales are not Open Source projects at all, they're based on Apple's proprietary graphics and other development APIs.
   
   So the hypothesis that Apple's recent success has been largely due to their basis on an Open Source kernel is without merit. While the Darwin kernel and FreeBSD portions of the OS are indeed contributory to the success of the OS, they are far from the only reasons why Mac OS X is such a good operating system or why Apple is being so profitable today.
   
   usw...

   chinggatchgook at 04:40pm on Sunday, February 24, 2008

10. Gary, I know about Canon's A-DEP function but, as you say, it's not quite the same thing. I agree it's way better than nothing, but then it may well be a Canon patent that no other manufacturer is allowed to use. My suggestion could be considered and implemented by anyone in the industry, for the benefit of all.

    Zoltan Arva-Toth at 09:30pm on Sunday, February 24, 2008

11. A great idea, i like it very much and I think that I would use it many times for my shots.I am amazed that no producer has still thought it. Maybe that there is some stange proble or difficulty to implement it?

    Francesco Calamida at 09:55pm on Sunday, February 24, 2008

12. my canon a2e film camera had a two touch a-dep setting. you positioned the central focusing point over the closest object and half depressed the shutter button then did the same for the farthest object and the camera would set the proper fstop and hyperfocal distance itself. if the range was greater than the smallest fstop could handle the fstop would blink in the viewfinder. this was great for landscapes and macros and was easy to use. it worked with all lenses including zooms. i have no idea why canon has not included this two touch system on their digital cameras as it was the reason i purchased their brand in the first place. go figure.

    frank cangialosi at 01:34am on Monday, February 25, 2008

13. Yes, please !! Great for the experienced and for beginners who will appreciate what this teaches them about DOF.

    Tom at 02:17am on Monday, February 25, 2008

14. i used to use the method on my old olympus c750 successfully for action or low light shooting; now on fuji s6500fd.
    as i remember ricoh 6 or 7 has this technology implemented already. finally there is a great resource at your disposal - http://www.dofmaster.com

    Igor Streambling at 05:10am on Monday, February 25, 2008

15. I'm no optics guru, but I think that hyperfocal distance is selected as the point that reaches a specific sharpness. It is related to the circle of confusion I think.
    
    But in our days of very different sensors (full-frame, APS-C, more or less pixels), I anticipate endless discussions on what value should be selected.
    
    Don't you think this could be THE problem that will prevent that otherwise very good idea from taking place ?

    Diego Coste at 10:38am on Monday, February 25, 2008

16. Diego, this moud would be implemented in the firmware of a camera, not in the lens. So, for a specific digital camera the radius is known and can be considered the size of a pixel.

    Renato at 02:10pm on Monday, February 25, 2008

17. ...this mode... above

    Renato at 02:12pm on Monday, February 25, 2008

18. It would be very nice to have this on a DSLR. For smaller cameras, this already exists in several models. Casio, for example, calls it "Pan focus mode". That mode is available on several of its Exilim Z-series cameras.

    Itai at 09:27pm on Monday, February 25, 2008

19. I'd love this in a camera! I currently have a hyperfocal table printed out and taped to the back of my camera (G6, so it fits nicely behind the LCD).

    David Bump at 04:25am on Tuesday, February 26, 2008

20. ricoh cameras have had a setting called snapshot mode (hyperfocal) for quite some time. Not new news.

    lance at 01:29am on Wednesday, February 27, 2008

21. brilliant. really.

    Jim at 01:51am on Wednesday, February 27, 2008

22. MOTION PICTURE CAMERAS.
    
    Hyperfocal Distance is how they keep the subject in focus a lot of the times in the movies. Since in motion pictures the subject moves all the time, the DPs and Assistant Cameramen are all very well versed in the Hyperfocal distance of the lenses given the Aperture setting, thus enabling them to use the follow-focus as they track with the subjects' movements.
    
    This would be highly useful also for still photography if one were to shoot moving objects a lot, to know what Stop to gauge in order to get a certain look to the shot using Hyperfocal Distance.

    AA at 08:06am on Friday, February 29, 2008

23. great idea.
    
    along a different vein, i would like to see camera manufacturers develop an auto RAW exposure where the camera automatically figures the correct settings (be it in shutter or aperture priority mode) to expose-to-the-right based on a live histogram's reading of the reflective luminance of a scene using evaluative metering (i think that's what it's called where it's based on the whole image and not on center weighted or spot metering). this should not be a hard thing to do. and this is the proper way to expose RAW for maximum data capture without clipping channels so why not automate it so you don't have to keep chimping at the LCD screen. it's like point-and-shoot operation in manual exposure mode.
    
    following that concept, why not simplify the metering interface so that it's more intuitive using a stop light analogy. so when you're doing manual metering for JPEG shots, you have a simple meter that shows green in the middle for properly exposed shots, yellow on each side to show slight over/under exposure (say +/- 1/2 stop?) and red to show anything beyond +/- 1/2 stop. a lot faster workflow in my opinion.

    chester at 04:34pm on Wednesday, March 05, 2008

24. Kodak and Carl Zeiss have now provided their feedback - see the end of the article.

    Mark Goldstein at 04:34pm on Monday, March 10, 2008

25. Most of the low end Canon EOS range 400D, etc. have the A-Dep mode. I've never used it as I'm always trying to concentrate on shallow DOF at f2.8 as I shoot mainly portraits. But I can see the benefit in landscape work

    Derek Barrett at 10:21pm on Saturday, March 15, 2008

26. I think it would be better to have an AF mode which optimised DOF from a selected near object to infinity. My article at http://www.users.bigpond.net.au/Chris.Jones/DOF/dof.html advocates zone focusing in preference to using the hyperfocal distance.

    Christopher Jones at 05:37am on Sunday, March 23, 2008