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The other day it just dawned on me that determaning where the camera should be focused at in order to achieve hyperfocal distance is not so easy as with manual focus 35mm gear, which has distance markings on the lens. Since such markings are not present on a 4x5 lens or the camera, how do you know where to focus in order to achieve thehyperfocal distance?
You can make yourself a distance scale. My speed graphic has a distance scale on the bed.
Many of the lens specification pages have the Hyperfocal distance/f-stop information on them.
It is then a simple matter of focusing (carefully) on something at this distance and recording the bellows' extension on the rail.
How you do this marking is up to you, but keep in mind that it needs to be repeatable. So, if you have rear extension, you need to zero this somehow so that it is repeatable in the field.
Be sure to read this article and the Hansma article within.
http://www.largeformatphotography.info/fstop.html
I know of a visually impaired LF photographer in England who shoots architectural interiors using hyper-focal techniques. He has calculated the extension for the lens at a typical distance and f/stop.He sets up the camera with pre-cut sticks between the front and rear standard.
The more time one spends in the field, the sharper one’s awareness of “field conditions” and their complications.
For example, let’s say you’ve finalized movements, focus, and aperture for “official” hyperfocal distance. The variable wind, the changing light, your filters, the reciprocity of your film – well, I could go on, but let’s just say your real choices at shutter snap, especially the one about aperture, will often be different than fancier choices from charts & blackboards.
The field is where compromise is king. ;)
Before the lab technicians object, I’ll add that mental exercises do have their use as a “starting point,” making the complications of practical work easier to understand, anticipate, and address. And besides, they provide splendid help for visually impaired photographers, like the clever one Drew mentions above.
keep in mind that on a hot day the glass and lens barrel expand with heat and your DOF scale can be off due to heat expansion!
Pencil hacks on a pc of masking tape are what most people do. You can use your loupe and actually check what is focus at a given aperture, then shoot a test sheet and loupe it to be certain.
Back in the day, the practical use of Polaroid Type 55 was that you could shoot it and loupe the negative to see if your DOF and sharpness were holding up.
LOL thanks for the practical advise.Quote:
keep in mind that on a hot day the glass and lens barrel expand with heat and your DOF scale can be off due to heat expansion!
This is confounded by the change in atmospheric density which changes the refractive index - mirages anyone?Quote:
Originally Posted by ki6mf
Seriously, calibrate your focal length scale at three temps (hot, medium and cold) and you should be fine.
Some photographers freeze their cameras as well as the film to avoid this.
Those were the days, sorely missed. :(Quote:
Originally Posted by Frank Petronio
When T55 went away, the loss of “instant feedback” in the field w/ such a fine film swept some film users I knew into digital. (Really! They were my friends.) When T55 resurrects – and all my praying means the Second Coming can’t be far away – those who were lost will return to the fold.
Pray with me. Believe. And while we wait, one should beware the seductions of hyperfocal charts – easy promises at the start, a false religion in the end.
Have been gypped by the Impossible Project -- crap film in pretty packaging -- I'm not holding my breath. As far as I'm concerned those guys are bigger scam artists than the people who sell Lomos for $100 a pop.
The hyperfocal distance is obtained when you move the lens back from infinity focus by
F-number times CoC
where Coc is the diameter of the maxium allowable circle of confusion.
What you choose for Coc is up to you and dependent on a variety of factors such as the size of your final print and how far you expect to view it from. A common choice for 4 x 5 format is 0.2 mm.
So, say you are shooting at f/16 and you use Coc = 0.2 mm. First focus as carefully as you can on infinity and then extend the lens an additional
16 x 0.2 = 3.2 mm
Since it is difficult to measure small distances along the rail, I suggest you make a scale to tape around your focusing knob. The focusing knob is geared down from the rail so a longer distance on the focusing knob produces a shorter distance on the rail. Make one or more complete turns of the focusing knob and measure the distance the standard moves on the rail. Measure the circumference of the focusing knob and divide one of these distances by the other to determine the multiplier.
Since it is difficult to make precise measurements of this kind with such small distances, it may be better to proceed optically. You can tell you are focused at the hyperfocal distance, if you are at the point where infinity just remains in focus as you extend the lens. This works reasonably well if you are stopped down to at most f/11, or, if you have a good eye, at f/16. If you need to stop down further , you can can obtain the proper extension beyond infinity by multiplying by the ratio of the f-numbers. So suppose you are shooting at f/22. Find the extra lens extension beyond infinity which works at f/11 and multiply it by 22/11 = 2. This is easier than it sounds because you don't actually need to know the distance for f/11. You can just mark it off on a strip of paper, and then double that distance by folding the paper.
These methods all suffer from the difficulty of placing the lens exactly where you want it. It is much easier to use the near point far point method which Eric Woodbury referred you to
at
http://www.largeformatphotography.info/fstop.html
I would just add one comment. I find using Hansma's table to be too conservative in choosing the f-stop. Another method, which I find works, is to take the focus spread in mm (the distance on the rail between the near point and the far point), multiply it by 10 and divide the result by 2. So if the focus spread if 4 mm, I would use 4 x 10/2 = 20, i.e. I would stop down to f/22. This gives you what would theoretically work under perfect conditions, so it would be wise to stop down an extra half or full stop.
Finally it is important to realize that anything you do based on what you see on the ground glass is based on how much magnification you apply. The calculations above are based on the assumption that you are looking at the 4 x 5 gg under 2 X magnification. If you use a 4 X loupe, that makes you twice as picky, i.e., in effect if reduces the effective Coc by a factor of 2. But that has the advantage that if something looks okay that way, it is likely to look okay in the final print because it has a built-in fudge factor. I think the quickest way around all of this is to use a 4 X loupe, and examine the scene at the desired f-stop, provided things are not so dim that you can't really see if things are in focus. If everything you want looks in focus, it will probably be in focus in the print, provided you don't to something foolish like viewing the print with a magnifier from close up. If your desired f-stop makes things too dim, you can examine the scene at f/11 or f/16. If you stop down further then approximately at least you will extend the range in focus by the ratio of the new f-number to the viewing f-number.
Remember also that for a static scene at least, you can't go wrong by stopping down a bit too far. Theoretically doing so can lead to fuzziness due to diffraction, but that seldom is a real problem in large format photography. However, if there is some motion in the scene, even of foliage moving in the wind, that will be visible with the longer exposure times necessitated by the smaller f-stops, so it can be quite a feat finding the best compromise between loss of sharpness due to depth of field and loss of sharpness due to subject motion.
A better question might be "why?" Various assumptions that may or may not be accurate for you and your standards are built into hyperfocal distance scales. They never worked well for me.
Hyperfocal distance always works for me....
as long as my subject is at the hyperfocal distance:D
You are of course completely correct. But, it is also true, that if you've managed to figure out, perhaps by lots of experimentation, where to place the standards at different f-stops to be focused at the hyperfocal distance, according to standards which make sense to you, and you are mainly interested in landscapes which go to infinity, then you can save yourself a lot of time in setting up your camera. Of course, experienced large format photographers can come pretty close to the same thing by just stopping down to some favored f-stop and looking at the gg as they focus and frame the scene.Quote:
Originally Posted by Brian Ellis
I typically spend much more time trying to figure out where to place the camera and how to frame the scene than I do focusing and estimating depth of field.
Preach it, brother!Quote:
Originally Posted by Heroique
By definition, shooting at the hyperfocal distance is constraining sharpness at infinity to your minimum standard. If you decide you want to make a bigger print than the one you used to choose your circle of confusion size, you'll no longer meet your own standard of sharpness.
Rick "Praying for the return of Type 55, but not believing" Denney
Goodness. All this mathematics. Einstein would be proud.
I loved mathematics when I was a young upcoming engineer... all that calculus and physics, statics, and dynamics...
But now my brain is old and lazy. And as another poster said, I spend more time picking a camera position and composing the scene than I do worrying about hyperfocal distances while focusing.
The bottom line is film and processing costs are cheap compared to the costs in time, effort, and money in the "getting there" where good photo opportunities exist. (I think I remember that statement... maybe I've used it before.)
So for me it's easy enough to adjust focus and f-stops a tiny bit and shoot another sheet or two.
My opinion. Bob G.