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Roger Hicks
06-28-2010, 00:28
This seems to be a perpetual source of confusion and dispute, and I can't see why. By definition, it's the zone either side of the focused point that is acceptably sharp. We all define 'acceptable' in our own ways, which should in itself be a clue, and obviously, 'acceptability' varies with subject matter, composition, enlargement size and viewing distance. Also, there are trivial differences (as between M8 and M9) and major differences (as between a mobile 'phone and an 8x10 inch camera).

Why, then, are there so many absolutists around, trying to reduce the whole question to mathematical formulae, good for all formats and all time? The d-o-f guidelines on lenses are just that: guidelines, based on stated or unstated assumptions. Thus, for most Leica lenses I tend to use the next smallest aperture, e.g. if I am shooting at f/8 and want to check the d-o-f, I use the f/5.6 markings. What do you do?

Ceers,

R.

shimokita
06-28-2010, 00:50
with the SMC Takumar 28mm 3.5 I just line up the orange marked distance and the orange marked f8 with orange diamond on the dof scale... adjust the shutter speed and fire away... no thinking at all...

Casey

Brian Sweeney
06-28-2010, 02:00
Basically, I do not use the depth of field marks. Their exact position on the lens is determined by "a mythical viewer observing a mythical image enlarged to a specific size only known by the person deciding where the DOF lines should be set on the lens."

It based on perception. Perception of anything but the image I am about to make.

maddoc
06-28-2010, 02:09
depth-of-field scales are nice guide-lines for me that I sometimes use to roughly estimate what could be in focus and what not. Everything else about it is to scientific for me

Leigh Youdale
06-28-2010, 02:19
When I used ancient folding Voigtlanders with no rangefinders they all had DOF scales engraved on the lens. Very useful when distances were estimated.
My Rolleiflex has a neat moving scale showing DOF on the left hand side of the camera, my Nikon pre-AI lenses have a DOF scale engraved on them as do my modern Cosina Voigtlander lenses. I'm less inclined to use the scales when I have a rangefinder to verify but if in doubt I do.
If I had unmarked lenses I'd use the rule of thumb that says "one third in front of the focused distance to two thirds behind".

pvdhaar
06-28-2010, 02:25
I only use the DOF guides as a rough indication of what will be acceptably sharp when I'm shooting from the hip. I set the distance at 100x the focal length (e.g. 5m for a 50mm lens and 2.5m for a 25) and the aperture at f8-f11. I look at the scale and know how much I can deviate from the set distance..

For landscapes, I use infinity focusing and set the aperture to f11-f16.. everything else follows. I don't worry about the DOF guides, because even if you shoot near/far stuf, you can't even get anything relevant comfortably in the frame that's outside the DOF.

Finally, when I'm shooting where exact focus counts, I just use three apertures: f2, f5.6 and f16; shallow, medium and deep DOF. I don't use the DOF guides.

user237428934
06-28-2010, 02:54
I used to have the cv 25mm (old version, no rf-coupling) and for landscapes I always aligned the infinity mark with the aperture I used. It worked all the time. Perfect.

oftheherd
06-28-2010, 03:06
When I used ancient folding Voigtlanders with no rangefinders they all had DOF scales engraved on the lens. Very useful when distances were estimated.
My Rolleiflex has a neat moving scale showing DOF on the left hand side of the camera, my Nikon pre-AI lenses have a DOF scale engraved on them as do my modern Cosina Voigtlander lenses. I'm less inclined to use the scales when I have a rangefinder to verify but if in doubt I do.
If I had unmarked lenses I'd use the rule of thumb that says "one third in front of the focused distance to two thirds behind".

My VAGs don't have DOF markings, but then I guess it is figured they don't need it. You are correct on the 1/3 in front and 2/3 behind according to all I have read. I don't think I have ever seen a lens marked that way. They are always equal distance on either side of the middle mark.

I have use the lens markings on many occasions. I tend to try to be conservative, knowing they are approximations only. I have used them on both RF and SLR.

Dave Wilkinson
06-28-2010, 03:08
This seems to be a perpetual source of confusion What do you do?

Ceers,

R.ask the audience, phone a friend, or go 'fifty-fifty'.

lorenzo1910
06-28-2010, 03:23
In the past times I was obsessed by the (subject) "out of focus" issue and I was used to close as much as possible the diaphragm to get as much DOF as possible...now I try to get a shallow DOF just because is more pleasant...but I never mind at the DOF scale on the barrell...maybe I'm wrong...maybe...

http://img138.imageshack.us/img138/4740/crop0011bgg.jpg (http://img138.imageshack.us/i/crop0011bgg.jpg/)

lorenzo1910
06-28-2010, 03:42
Oh no...I did the "as much" mistake again...I beg you pardon Roger...

Roger Hicks
06-28-2010, 03:46
Dear Lorenzo,

'As much as possible' is perfectly correct.

It's only when you begin a sentence wth "Much as..." that it shouldn't be "As much as..."

Thanks for everyone's stories. There's more to this than I thought...

Cheers,

R.

Sparrow
06-28-2010, 05:17
I must be peculiar, I seem to use the DOF scales more often than not to check something is out of focus not in, in order to reduce it’s importance in negative space or isolate the subject

antiquark
06-28-2010, 06:26
This seems to be a perpetual source of confusion and dispute, and I can't see why.

When calculating DoF, four things can be taken into account:

- angle of view
- sensor size
- focal length
- print size

The problem is, when comparing different systems, you must decide which of those elements are "normalized" so that they're equivalent across the systems. For conventional DoF calculations, two things are normalized:

- angle of view
- print size

I think the main problem is that people don't agree that those two things are the invariants in DoF calculations. They think that other things should be considered as constants.

However, in a practical sense, using angle of view and print size never leads to absurd conclusions. For example, say that we assume that focal length is the constant. Then as soon as someone pulls out their cellphone (FL = 4 mm) then you have to also search for a 4mm lens for your Hasselblad, which is absurd.

Gumby
06-28-2010, 06:45
ask the audience, phone a friend, or go 'fifty-fifty'.

flip a coin.

Lilserenity
06-28-2010, 06:58
Not sure what all the fuss is about. If I am shooting predominantly landscape/architecture I set the lens the maximum aperture that I can up to f/8 -- if with the available light I can get more than f/8 technically, then I increase the shutter speed instead.

So then I maximise the DOF with the infinity mark just beyond the f/8 mark on the lens and then shoot all day, just making sure the lens hasn't been knocked. That way I get the most detail I can on the ISO 100 films I tend to shoot.

Anything else which requires people in foucs, well I pretty much just focus on them and shoot, I don't pre-focus, miss too many shots that way, and I don't shoot from the hip either (unless with my TLR which dangles down to about that far on me!)

As for which aperture to use, well I just use my head and work out what kind of shot I want and recall previous shots that worked and their aperture in my head and go from there. Generally speaking if I am doing street photos for 35mm I'll shoot at f/2.8, 50mm f/4 and 100mm f/5.6 or f/8.

Vicky

Rob-F
06-28-2010, 07:13
DOF is also affected by how sharp the lens is, in the plane of focus. If shooting with an ASPH or other very sharp lens, I will stop down one more stop than the scale calls for; but not so far that diffraction will work against me. With most of my lenses, I just trust the DOF scale.

At times when I can't stop down enough, I might just focus on the most important area, and let the rest be a little soft. Chances are, they won't be all that soft, and I will get away with it.

JohnTF
06-28-2010, 07:40
When I got my first "adjustable" camera, my Signet 50, I just went balls out to nail the distance as closely as I could to the actual distance of the main subect, set a comfortable speed, and the stop followed.

It had a linked stop and speed mechanism, but I mostly ignored that.

More recently, I shot the same way with a Leica Standard, and it still works.

Most recently, using the CV lenses that are not linked, I was surprised that sometimes I was a bit off with the M8, and now I use Roger's -- "use the next stop down" method. I was getting acceptably sharp images with the 12mm, but not as sharp as I thought, so am paying a bit more attention in what I set.

The indicated DOF was so great I was getting sloppy, but it is a long way back from AF in my Contaxes.

I am not sure of all the math involved on using DOF scales on the M8, but I am sure I was not getting what I was looking for, so one stop "safety" is it now, and when someone explains the math to me, it will be a footnote.

In another direction, These days I am much more interested in the quality of the out of focus areas that compliment the main subject, so it becomes more involved than just getting the subject sharp.


I know I am getting old when I think beginners should start with two cameras, one that does everything for them, and one that they have to set everything, well, perhaps three, one that cannot be set.

I did distance estimation and measurement exercises with my classes, and it is surprising to all involved. We began with cubits, and ended up determining how much it would cost to fill the hallway with soda.

I had a lot of practice in my early days with the Kodak, but that was feet I believe.


Regards, John

bigeye
06-28-2010, 07:40
It seems to reflect the times. I'm playing with an Isolette-Speedex, which was considered serious hobbyist camera in its day and it doesn't have any focusing aids at all. It was accepted to use DoF as your sole means of focusing in the early '50s.

It has to do with the modern fixation with metric measurement.

In the '50s, image quality was measured bluntly in furlongs, hogsheads, and firkins. Then the British accepted the precision of an old French measurement system, and look what happened.

- Charlie

Roger Hicks
06-28-2010, 11:33
DOF is also affected by how sharp the lens is, in the plane of focus. If shooting with an ASPH or other very sharp lens, I will stop down one more stop than the scale calls for; but not so far that diffraction will work against me. With most of my lenses, I just trust the DOF scale.

At times when I can't stop down enough, I might just focus on the most important area, and let the rest be a little soft. Chances are, they won't be all that soft, and I will get away with it.
Dear Rob,

VERY true. 'Soft' lenses effectively have more d-o-f.

Cheers,

R.

JoeV
06-28-2010, 13:39
Regarding "DOF," I will leave it to the physicists in the audience to explain the difference between Depth of Focus and Depth of Field. ;)

I think the most valuable concept yet presented in this thread is that lens markings are based on assumptions, and in general are but guidelines.

I think what many are in search of is the Magic Formula that will produce the Perfect Image, without further intervention on the part of the photographer; as if art could be distilled down to some mechanical process, starting with pushing a button and ending with Fine Art spewing forth from one's printer, without trial and error and labor the intermediary. Yes, I too would like for the process of image creation to be as goof-proof as possible, but one must understand the limits of the process through experience just as much through mathematical calculation.

~Joe

batterytypehah!
06-28-2010, 14:10
My VAGs don't have DOF markings, but then I guess it is figured they don't need it. You are correct on the 1/3 in front and 2/3 behind according to all I have read. I don't think I have ever seen a lens marked that way. They are always equal distance on either side of the middle mark.

That's because the distance scale is not linear. If you look at the distances, 1/3 to 2/3 is about right. Example: Take the distance and DOF scale on a Contax body (which, because of the in-body helical, is the same for all 50mm lenses). Distance set at 8 feet gives you a DOF at f/8 from 6 to 12 feet, i.e. 2 feet in front of and 4 feet behind your set distance. Hence, 1/3 to 2/3.

sepiareverb
06-28-2010, 14:57
I shoot everything at f22 so I don't have to think about it. I mean, I have enough to worry about getting the exposure right.

Brian Sweeney
06-28-2010, 15:10
This problem is caused by photographers using lenses instead of pinholes to create their images.

Just quit using them, and switch to pinholes.

xwhatsit
06-28-2010, 15:27
Quite useful on my Vito II with no rangefinder (and not even an accessory shoe to attach my separate rangefinder!). Also useful in the same way when scale focusing with one of the Lynx (Lynxes?).

charjohncarter
06-28-2010, 18:05
I love just having DOF control available. It was even more fun when I shot Kodachrome 10 & 25.

JohnTF
06-28-2010, 18:11
It seems to reflect the times. I'm playing with an Isolette-Speedex, which was considered serious hobbyist camera in its day and it doesn't have any focusing aids at all. It was accepted to use DoF as your sole means of focusing in the early '50s.

It has to do with the modern fixation with metric measurement.

In the '50s, image quality was measured bluntly in furlongs, hogsheads, and firkins. Then the British accepted the precision of an old French measurement system, and look what happened.

- Charlie

They wanted base ten weeks and months, that did not work out so well.
;-)

Actually almost all systems are precise, the easy one that is a real system is the SI (Metric) system.

Avoirdupois is the French name for the British system only used, to some extent, in America. It is not a system at all, just many other units converted to each other with different meanings often attributed to the same name. Plus, we have begun to avoid fractions, and go to a decimal to toss in the mix, e.g. 1.34 " .

As for the British adopting the SI system, they did so legally, but not for real for a long time.

Roger will explain Whitworth (spelling?) as I am sure he worked on more than one bike or car with that system-- lots of fun, especially if you lose a bolt and really need to put it back.

I did have one problem with the SI system recently, I was zone focusing with my Collapsible Summicron, and after a few shots I noticed it was marked in m, not Feet, so I had a few very soft images.

Regards, John

rya
06-28-2010, 19:00
I have only checked my DOF marks a couple of times--ever. I know about what each aperture will give me, at each distance, and I learned it from printing 8x10s with notes of settings. Never did I really understand why so much clutter atop the lens barrel was necessary considering how insufficient those measurements are.

xwhatsit
06-28-2010, 19:53
I love just having DOF control available. It was even more fun when I shot Kodachrome 10 & 25.
Efke KB25!
Roger will explain Whitworth (spelling?) as I am sure he worked on more than one bike or car with that system-- lots of fun, especially if you lose a bolt and really need to put it back.
Whitworth is great! Never have to pull out my helicoil kit on old Brit bikes -- different story on my old Jappers! The amount of M8 and M10 metric fine coils I've had to tap...

Only thing is, lose a nut, try finding a new one at the fastener shop.

JohnTF
06-28-2010, 20:36
Right, on the MG TD we were rather careful with losing nuts and bolts, took a year to rebuild the motor-- it had been supercharged, needed oversize rings, a rebore, regrind on the crank, etc. We actually had some Sears wrenches marked with a "w".

The MG I have now is straight Avoirdupois I think, have a metric crescent wrench as well, it's 300cm long.

acheyj
06-28-2010, 21:33
Whitworth we used on the farm and soft metal, PROPER motorbikes and cars use BSF, lesser machinery used NC ,NF . Still have full set of "pommey" taps and dies. Of course just like practical use of D.O.F. I now use all metric and a very long spanner (they dont work loose !)

cheers.

ron.

Pico
06-28-2010, 22:04
CoC is important. Hasselblad suggests that for large prints, one uses the CoC for 35mm rather than the markings on the lens barrel.

ampguy
06-28-2010, 22:12
Freytag's '69 book "The Hasselblad Way" recommended .06mm coc for standard work, and .03mm for "critical work"

Leica's DOF lens markings are based on .023mm making them perfectly suitable for APS-C, APS-H, and legacy medium sizes.

CoC is important. Hasselblad suggests that for large prints, one uses the CoC for 35mm rather than the markings on the lens barrel.

Bob Ross
06-29-2010, 08:28
I have always thought of narrow DOF as an isolation tool (focus isolation) which is useful when the relationship between the subject and background isn't attractive. If you can't get narrow DOF (as with small formats), then you need to pay attention to the background's relation to the subject. How you go about depends on the final output size and probably your viewing audience. Knowing the COC stuff can be very usefull, but mostly at the intuitive level, because unless you can shift from analytic to creative mind-set and back, you could lose the moment.
If you got to have DOF control one of the best tools is a DSLR with a legacy lens attached that is used at operating aperture.
Bob

Roger Hicks
06-29-2010, 08:50
The oldest bits of the Land Rover (the gearbox, originally designed in the 1930s) use Whitworth, but otherwise it's mostly split between BS/BSF and metric - though AF spanners often work, because many have the same jaw dimensions AF as BS/BSF and even Whitworth. Of course part of the electrical system is BA...

The big advantage of a real car is that you can still get bits for it, but to make life REALLY interesting, three of the bleed nipples on the slave cylinders are metric and the other is BS or possibly AF.

Cheers,

R.

JohnTF
06-29-2010, 08:50
I have always thought of narrow DOF as an isolation tool (focus isolation) which is useful when the relationship between the subject and background isn't attractive. If you can't get narrow DOF (as with small formats), then you need to pay attention to the background's relation to the subject. How you go about depends on the final output size and probably your viewing audience. Knowing the COC stuff can be very usefull, but mostly at the intuitive level, because unless you can shift from analytic to creative mind-set and back, you could lose the moment.
If you got to have DOF control one of the best tools is a DSLR with a legacy lens attached that is used at operating aperture.
Bob

Part of being on your game, just as having focus zone set, knowing which way to turn the lens, choosing focal length, angle of view, -- all tools.

A bit of simplicity in isolation-- I do not care for many "busy" backgrounds with bright areas to draw the eye somewhere distracting to the image you want.

Some days it just seems you see all of this with the right subjects, and then there are the others, and the circle of confusion includes everything.

Often a disappointment when you cannot get position, or your equipment lets you down.

Regards, John

JohnTF
06-29-2010, 08:58
The big advantage of a real car is that you can still get bits for it, but to make life REALLY interesting, three of the bleed nipples on the slave cylinders are metric and the other is BS or possibly AF.

Cheers,

R.

Perhaps telling you which could be rebuilt and which were replaced?

Ford had a nasty habit of using ones much too small, 1/4" and with our winters, and salt, would break off-- bled one cylinder with a .004" feeler in the top of the cup, lasted longer than the car. The really right tools were then purchased for the next go around. Noticed the MG had 3/8" plated screws on a much smaller car.

Don't think many places rebuild much these days.

I know you like terms, perhaps you have not been told a Ford Wrench is a large hammer.

J

Pico
06-29-2010, 09:05
Efke KB25!

Whitworth is great! Never have to pull out my helicoil kit on old Brit bikes -- different story on my old Jappers! The amount of M8 and M10 metric fine coils I've had to tap...

Only thing is, lose a nut, try finding a new one at the fastener shop.

Aside - When Triumph motorcycle switched metrics, they went to American Standard. I think it was 1973. Very odd choice since America was considering metric at the time.

Sparrow
06-29-2010, 09:45
Whitworth machine screws are 30% stronger than there BS equivalent size ... not sure where I learned that useless bit of info

Sparrow
06-29-2010, 09:48
Aside - When Triumph motorcycle switched metrics, they went to American Standard. I think it was 1973. Very odd choice since America was considering metric at the time.

my tr6 has most thread sizes represented somewhere

antiquark
06-29-2010, 10:05
Freytag's '69 book "The Hasselblad Way" recommended ... .03mm for "critical work


Interesting how coarse that is. If you convert that to pixels, you get (60/0.03)^2 = 4MP!

Bob Ross
06-29-2010, 14:11
Part of being on your game, just as having focus zone set, knowing which way to turn the lens, choosing focal length, angle of view, -- all tools.

A bit of simplicity in isolation-- I do not care for many "busy" backgrounds with bright areas to draw the eye somewhere distracting to the image you want.

Some days it just seems you see all of this with the right subjects, and then there are the others, and the circle of confusion includes everything.

Often a disappointment when you cannot get position, or your equipment lets you down.

Regards, John

There are times when I don't want to bother with relationships other than to the light, so I go to isolation and minimalism and my viewers ask, "where is the rest of the picture?" :bang:
Bob

Brian Sweeney
06-29-2010, 14:20
Okay- just as this is settling down... Apples and Oranges. Stopping down for increased DOF means smaller aperture and slower shutter speed. This introduces camera shake. Most photographers shoot without tripods or other means to minimize the effects of vibration on a photo. Camera vibration at slow shutter speeds is likely to increase blur. This will defeat the use of a small aperture to increase the resolution of the objects in a photograph. All objects will appear equally blurry, so the DOF increases.

So- DOF is defined as the range that objects appear equally sharp, i.e. at the same level of focus. To increase the DOF of your image, shake the camera while you snap the picture.

JohnTF
06-29-2010, 20:13
There are times when I don't want to bother with relationships other than to the light, so I go to isolation and minimalism and my viewers ask, "where is the rest of the picture?" :bang:
Bob

Perhaps that says more about the viewer than the photographer.

Regards, John

Roger Hicks
06-29-2010, 23:20
Perhaps telling you which could be rebuilt and which were replaced?

Ford had a nasty habit of using ones much too small, 1/4" and with our winters, and salt, would break off-- bled one cylinder with a .004" feeler in the top of the cup, lasted longer than the car. The really right tools were then purchased for the next go around. Noticed the MG had 3/8" plated screws on a much smaller car.

Don't think many places rebuild much these days.

I know you like terms, perhaps you have not been told a Ford Wrench is a large hammer.

J
Dear John,

Another name for a hammer is a Birmingham screwdriver.

I have to confess that I don't rebuild slave cylinders either. New Girling ones are only 10-15. I can't see why anyone buys cheap Turkish or Chinese ones just to save another fiver. Same with master cyinders: 22 vs. 15 or so. Hell, my LIFE depends on those things...

Cheers,

R.

Sparrow
06-30-2010, 00:26
Dear John,

Another name for a hammer is a Birmingham screwdriver.

I have to confess that I don't rebuild slave cylinders either. New Girling ones are only 10-15. I can't see why anyone buys cheap Turkish or Chinese ones just to save another fiver. Same with master cyinders: 22 vs. 15 or so. Hell, my LIFE depends on those things...

Cheers,

R.

My dad, an engineer and "standards-man" often used the term percussive-screwdriver for a 2.5 lb copper faced hammer, or gas-spanner for an Oxyacetylene torch

If only Girling knew of the magical properties of Copper-Slip when applied to brake adjusters and bleed-nipples the would would be much less stressful

edit;
Another, when asked how tight something should be tightened was "until it snaps ... then back it off a quarter"

Roger Hicks
06-30-2010, 00:43
Ah, the 'blue spanner'.

Cheers,

R.

sam_m
07-01-2010, 23:47
Ctein wrote a series of very interesting articles on TOP:

Depth of Field Hell (http://theonlinephotographer.typepad.com/the_online_photographer/2009/06/depthoffield-hell.html)
Depth of Field Hell - The Sequel (http://theonlinephotographer.typepad.com/the_online_photographer/2009/06/depth-of-field-hellthe-sequel.html)
Deoth of Field Hell - The Coda (http://theonlinephotographer.typepad.com/the_online_photographer/2009/07/depth-of-field-hell-the-coda.html)

Well worth a read when you have time.

john_s
07-02-2010, 14:43
Freytag's '69 book "The Hasselblad Way" recommended .06mm coc for standard work, and .03mm for "critical work"

Leica's DOF lens markings are based on .023mm making them perfectly suitable for APS-C, APS-H, and legacy medium sizes.

More like 0.033 actually, similar to most other 35mm lens markings.

Sparrow
07-02-2010, 14:59
I think this as gone far enough now ... pass the Webly John