Hyperfocal distance....I'm really confused!

[chadlatta]

<p>I just picked up a Canonet QL17 GIII, cleaned it up and ran a roll of film through it. I love it, its a blast but......</p>

<p>I have a hard time focusing, especially on the fly. I am trying to figure out what settings I need to "preset" the focus so that I can shoot on the fly without using the rangefinder. But, I am really confused.</p>

<p>I found this chart http://www.squit.co.uk/photo/files/DofTablesRF_QuarterPage.pdf that list the different setting and DOF in meters for those settings. Am I correct in saying that, according to this chart, if I shoot at f/8 with my focus set to 5 meters, everything from 2.87 meters away to 19.5 meters away will be in focus? and so on with the other settings in the chart.<br>

When shooting manual, I have to consider the sunny 16 rule as well as all this so this chart, if its accurate, is a life saver....</p>

<p>Thanks for your help.<br>

Chad</p>

[jim_momary]

<p><a href="http://www.dofmaster.com/dofjs.html">http://www.dofmaster.com/dofjs.html</a><br>

Yep, that's correct. But, bear in mind THE sharpest plane will be @ 5 meters (in your example).<br>

Things progressively further away from that, but still in the hyperfocal range, will get blurrier as you reach the upper and lower limits.<br>

It's a question of "acceptable focus", and that's a somewhat nebulous term. This idea is to give the 'largest' DOF possible at any point for a given F stop. That's sort of how I look at it in my non-pro mind.</p>

<p>Jim</p>

[allardk]

<p>For some reason everybody keeps referring to dofmaster for DOF calculators. <a href="http://www.stegmann.dk/mikkel/barnack/">Barnack</a> is much better if you ask me. A great feature is that it can give you a 'blur circle vs distance' graph, which tells you much more about DOF than two simple numbers. Basically, it will tell you how sharp or unsharp an object at a certain distance is.</p>

[craigd]

<p>@Allard, I think people like dofmaster because it's an interactive web site that works on all platforms, rather than an executable you have to download that only works on Windows.</p>

<p>@Chad, Jim makes a good point that perfect sharpness really only ever happens in a very narrow plane. The concepts of DOF and hyperfocal distance tend to confuse people because they seem to suggest that you really have everything in perfect focus between two points, and further that those two points are adjustable. This isn't really true; as Jim says, it's more a matter of determining a range within which things will be close enough to "in focus" that they will look good. What may not be obvious is that "close enough" is not just a matter of focal length, distance, and aperture, but also of image enlargement. The common "circle of confusion" definition of 0.03mm is based on the assumption of 35mm film printed no larger than 8x10". If you were planning to print at, say, 16x20" or 24x30", you would need to use a smaller CoC value, which would result in shallower DOF and greater hyperfocal distances. So the situation is really somewhat more complex than simple charts like these make it seem, but the charts are probably accurate enough for most people most of the time.</p>

<p>Your interpretation of the chart is pretty much correct. According to chart 1 for your Canonet with its fixed 40mm lens, hyperfocal distance at f/8 is 6.71m, so if you focus at 6.71m or greater, you will have DOF from roughly half your focus distance all the way to infinity. With focus at 5m, you will have things "reasonably in focus" between 2.87 and 19.5m. It should be easy enough to validate this by experiment.</p>

<p>Congratulations on the Canonet. It sounds like a lot of fun.</p>

[Alan Marcus]

<p >When you focus, you are changing the position of the lens as to its distance from the film. When focused on an object 5 meters (16.4 feet) away, objects at that distance will be in sharp focus. However, a zone of acceptable focus exists fore and aft of 5 meters that will appear sharp and clear in the finished picture. That zone of acceptable sharpness is called depth-of-field. </p>

<p >The span of the zone of depth-of-field is a variable. The zone expands when you reduce the size of the lens aperture. The zone contracts when you increase aperture size. Other factors are less obvious but they include camera-to-subject distance, the size of the finished print, the distance observer-to-finished print, subject matter, and degree of enlargement of the finished print. Because there are so many variable a table of depth-of-field, such as the one you reference, is based on typical print size and print viewing condition. </p>

<p >Now the hyperfocal distance is the distance focused upon whereby the zone of depth-of-field extents to just touch infinity (as far as the eye can see). It is useful to set your camera to the hyperfocal distance when you don't want to muddle with focusing. Simple box cameras are set this way allowing the occasional photographer operate without a need to focus at all.</p>

<p >The penalty paid is the lens aperture must be quite small and this limits the picture taking opportunity to bright sun, likely 10AM - 4PM. If you wish to expand picture-taking opportunities into early morning or late afternoon or flash etc. you will need to open up the aperture and this act contracts the zone of depth-of-field and the penalty is the need to focus. </p>

<p >As to exposure, this camera has a built-in light meter. If it is operational you can use it instead of the sunny 16 rule which is OK but not as accurate as a light meter reading. </p>

<p >It is fun to play with antique cameras of the 60's and 70's. Maybe some folks are compelled to use them because of economic conditions. Let me add that we have come a long way in camera design, especially auto functions like focus and exposure. Why not put this guy on the shelf and admire from afar. How about a modern digital point-and-shoot? </p>

[lachaine]

<p>Oh come on, now. I think photographers could focus and choose exposure just as well a century ago as the high-tech gadgetry can today... and I choose my 1970's Nikon FM most of the time just because I enjoy it more.</p>

<p>For the OP, hyperfocal focusing was never meant for fine art perfection, for loupe owners, or for 100% crop gawkers. It simply makes use of the fact that a lens has a certain range of depth of field at given apertures which allow for reasonable focus without worrying about it. Many old cameras with a fixed lens were designed that way, with fixed focus and fixed aperture, so Dad's with Brownies or Polaroids could take snapshots of anything that was 8 feet or more away... more or less.</p>

<p>It's useful to pre-set a camera to hyperfocal even today, even a digital one, for cases where the AF might hunt and peck to gain focus, or when you really want absolutely instant shutter response. Street photography was mostly always done this way, and so was a lot of news photography. Not as necessary today with fast autofocus, but still a valid concept. No harm in trying it.</p>

[chadlatta]

<p>Thanks for the response.....I think I am starting to get it. Its just a lot to wrap your head around, at least for me...its just confuses me!</p>

<p>So, I am assuming shutter speed doesn't come into play here at all, other than exposure?</p>

<p>@Alan Marcus: The light meter works properly and I adjusted it to work with a new, higher voltage battery. I ran a test roll through it shooting only in auto and everything work just fine. The problem with shooting in auto is that I have to focus with the rangefinder. Its not that bad and with a little practice it may not be an issue, but its tough to get it done quickly.</p>

<p>I shoot with a D80 right now and have a blast. But I love film. I started with a Nikon FE2 and then went to to digital recently. The thing I like the most is that I cant obsess about a shot because I dont know exactly what I got until I develop it! With digital, I am always chimping and shooting and chimping....etc. I dont have an excuse if I miss a shot. With film, I just shoot and get what I get. Its relaxing.<br>

I have about 4 rangefinders, 3 or 4 TLR's and a few different polaroids. I love shooting with all of them. Collecting, cleaning and fixing them is pretty addicting. I have had to stay away from ebay for a while because I have too many to shoot with now!</p>

[craigd]

<p>@Chad: "So, I am assuming shutter speed doesn't come into play here at all, other than exposure?"</p>

<p>Right. Shutter speed doesn't affect DOF. Your ISO level doesn't affect DOF either. DOF can be calculated just using aperture, focal length, and circle of confusion (which in turn is determined by how much you expect to enlarge the image from its original format; in general it is assumed that a smaller format will have to be enlarged more).</p>

[lachaine]

<p>Don't you have depth of field markings on your lens?</p>