Does hyperfocal distance apply in large format photography when using tilts or shifts?

[ellis_vener_photography]

<I>"Even though I am a Merklinger fan, I will gladly disclose to

those newcomers to tilt, sometimes his approach is a bit

cumbersome in the field without additional tools, such as a laser

rangefinder, angle finder and a sketch pad.</I><P>Exactly.Thank

you for making my point Bill. <P>Alex and other newcomers to

large format work, please don't be scared off by their approach.

Try it if you like but there are more much direct and just as

precise ways to "skin the cats" of determining depth of field and

using swings and tilts to make the shot and get the extremely

high level of resolution your equipment is capable of.<P>Happy

Schiempflugging to all of us large format photography fans.

[kelly_flanigan1]

Bill; do you own a SUUNTO Clinometer? They are great to measure the height of objects

[jerry2]

Kelly, yes I do, and I use it quite often and yes it does work very well! In conjunction with a cheat sheet and a laser rangefinder, I can tell the height of just about anything very fast.... I once saw a combination unit made, that included both into one. You pointed at the base, then the top and it gave you the height...it assumes a right angle at the base. Can't remember where i saw it.

[ellis_vener_photography]

Out of curiosity, Bill how long does it take you to set up, do your

measurements, draw your diagram (if necessary), make your

calculations, double check all of the above apply them to the

camera and make your image?

[jerry2]

Well Ellis, as you can tell from what I wrote above, this depends greatly on the scene. A best case / worst case scenario is like this.....

 

Best Case....It's obvious where psf is intersecting below lens, do simple math in my head, fl/j*5 = tilt angle, set tilt, focus for the far, tighten controls and shoot.... very simple, - from the time camera and lens is on tripod, I can be tripping the shutter in less than 30 seconds, which includes light meter readings. I am very fast when things are simple....

 

Worst case scenario, .... a complex tilt scene which involves, laser rangefinder, clinometer, scaled drawing, look up charts, etc.... well, this has taken me as long as 10 - 15 minutes at times. Considering you are tired, bugs bighting you, light changing, etc. it is not ideal conditions to be doing all this. But of course I apply some common sense.....If the light is changing fast, I won't even attempt all this - I just set up, make an educated guess, stop down to the max. and shoot.... sometimes I can squeeze a 3x enlargement out of rush shot, and sometimes I get lucky and get a full 10x. This is in essence what it all boils down to.... regardless of how I go about shooting the scene, the chrome always looks good on a light box, but my goal is to make big prints, so enlargement factor is a key...and when DOF values and the psf is not perfectly accurate, then enlargement potential is the penalty I must pay. This is why I stated early..... if my goals were making 8x10 prints from 4x5 chromes, I would never get bogged down with all this mess!

 

Of course complex scenes that are worthy of all this time and effort, I may do the math one night, then when I re visit the scene the next day, of course I can set up in less than a minute.

[kelly_flanigan1]

Bill; good story about the setup times..<BR><BR>Most of the SUUNTO Clinometers we sold were to cell phone tower survey guys..they want to quickly get a good height estimate ("survey of their competitions towers in the area")....at the standard 1 chain (66 ft) distance; the clinometer reads to 200ft height...Alot of tree guys use them also..<BR><BR>The Leica disto laser rangefinder is fantasticly accurate within 1/8 inch; the older models poop out a 300 feet.. The hunters and billboard guys go for the 300,400,500,600 yard laser rangefinders; their accuracy depends somewhat on subject shape; and usually is within a few yards..For signage studies I used a 30x40 foamcore white sheet as target; when going past the rangefinders specs! One old unit I used would roll over past 1000ft; and read 005 ; for 1005 feet....This was with the giant white target; and past the units 300 yard spec......<BR><BR>You are wise to use the clinometer and laser rangefinder.....Few people can estimate heights and distances consistantly well....Many Land Surveyors can

[ellis_vener_photography]

Thank you Bill those times are both better and worse than what I

expected. Most of my work gets used at everything from near

contact print size,but quite often ends up being enlarged by a

factor of 10 or 15X and occassionally larger (or a final print size

of 40 x50 inches or even as large as 60 x 75 inches. <P>I think

our misunderstanding seems to have been based on my use of

the term reproduction ratio -- by which I meant to the size ofthe

original object to it's reproduction on film, and your use of the

same term which seems to me to refer to the enlargement of the

negative or transparency to a print.<PP>Have you worked at all

with the Durst Lambda process?

[jerry2]

Kelly, very few photographers seem to be familar with these tools. I find them mandatory, even for box camera DOF. With out tools, you are focussing in the dark. Most many rangefinders require an ojbect of known size to focus on, such as a golf flag, these can be purchased for $15. But they are useless in the middle of the a landscape scene where you have nothing to reference. Hence the reason I use the DMG rangefinder that is very accurate up to about 1200 ft. After 1200 ft, most of the time they are at infinity, or near infinity based on the fl lens used.

 

Ellis wrote....I think our misunderstanding seems to have been based on my use of the term reproduction ratio -- by which I meant to the size ofthe original object to it's reproduction on film, and your use of the same term which seems to me to refer to the enlargement of the negative or transparency to a print.

 

Not to beat a dead horse, but, I never confused the two issues. They are totally independent issues which both affect the final outcome on film. Your reproduction ratio input is required to set focus properly. If a tree is 200 inches high and it appears on the gg at 2 inches, that represents 100:1. With a known fl lens, you can reverse calculate the trees distance. That is why the calc. is asking for the reproduction ratio, it's ultimate objective is distance, but as you can see, its 6 of one, 1/2 dozen of the other. But it's my guess, the real reason it asks for reproduction ratio, is because in close up work, you can use a disc in the scene and re measure it on the gg which simplifies the entire process. That's why I feel so strong the Rodenstock calc. may be geared for close ups. Now, the coc we both used in our calc, which also changes focus position will dictate enlargement potential, HOWEVER, making an error with estimating height and / or distance / reproduction ratios, will create error in the focus position, which in turn will compromise the enlargement potential on film. Hence the reason I keep mentioning enlargement potential, it's the final result of all the input data, regardless whether its Merklinger, Rodenstock or Sinar. It's the ol weakest link in the chain principle.

 

To make my point clear, if I could look at a tree and know the height, then measure it on the gg, I would not need all these other tools to accomplish what I am after. It does not matter if I am trying to estimate the height of the tree to enter a reproduction ratio in the Rodenstock calculator, or use it to determine where the psf will intersect under the lens for Merklinger, the bottom line is, I am still guessing the height of the tree. (Or more importanly for the psf, the distance of the tree, so as to determine the angle the psf will travel) So regardless of whether I wanted to use Rodenstock calc. or Merklingers, my point remains the same, in landscapes, it's nearly impossible to consistently guess these values. Land surveyors are good, but when you get in nature, there is so many false depth clues which throw you off, it's truly amazing. The only way someone will understand the difficulty of such, is go into the wilderness with a laser rangefinder, and possible a clinometer, and test yourself! Be sure to guess first, then use the tools! :-)

 

The real education I got in this area, was when I started shooting Medium Format Stereo with dual M7's. The film is used for the final product and seen in a stereo viewer with 4x magnification lenses. Our eyes can easily determine when something is not acceptably focussed. I had to perfect the exact lpmm on film, which turned out to be about 5 lpmm AFTER lens magnification, so it would appear sharp to our eyes! 2 lpmm after magnification appears fuzzy vs. 5 lpmm, however, 10 lpmm appears a tad sharper, but does not make the 5 lpmm look soft. So the film had to produce a minimum of 5 x 4 or 20 lpmm in every part of the scene, or the chromes were trashed. No Photoshop to save us here. (of course these lpmm get converted to coc in the DOF calcs) With such exacting requirments, this is when I finally discovered, without measurement tools, it was clearly a "hit or miss" proposition. After I perfected my DOF charts with the minimum coc my chromes can accept, I have had near 100% success rate getting each part of the scene to meet my min. sharpness objectives. As you can imagine, most scenes are pushing the envelope of DOF since there needs to be at least some near objects for the stereo effect. So quite often, I have to walk away from a good scene, as it's impossible to squeeze the DOF I want for asthetics with out compromising my minimum coc's. This is the utltimate lesson in coc's and accurately knowing distances in the field.

 

Of course the M7's are box cameras, so therefore I only need to use the laser rangefinder for distances. Using the rangefinder, I determine the distance of the near object and far object, look them up on my DOF chart, it tells me what distance I must focus at to meet this criteria, I use the laser rangefinder to find something at that distance and focus on it. Quite often I have to take the camera off the tripod, look around, to find something at that distance when there is nothing in the scene at that distance, then just re compose. Shooting MF stereo with dual cameras makes Merklingers tilt math seem easy! The math / charts for interocular seperations can really get confusing!

 

<PP>Have you worked at all with the Durst Lambda process?

 

Yes, I have used Durst, Light Jet and Chromeria.....but I no longer use these wet processes. About 1.5 years ago I have fallen in love with ink jet prints on fine art paper - in my case, water color paper. Ink jets have come a long way, and gives the look of the print an "artsy" look vs. the ol standard glossy photo look. Not cheap though, the good papers and inks run about $4 sq ft + labor, waste, etc.

 

Martin, I am still struggling with that final formula you wrote, did you get my spreadsheet I emailed directly to you?

 

 

 

[jorge_gasteazoro5]

Hi all, after reading 82 responses I have a few questions...One, does hyperfocal distance apply to large format when using tilt? I would like to see a show of hands, I think this would be more useful to Alex than the discussion that has been done so far. Two, how come Adams, Weston, Caponigro, Sexton, manage to get such great images without all those gadgets like range finder, inclinometer, etc?

BTW, my hat off of to those who understand and use Merkingler's method...I read the "in's and out of focusing" and frankly I could never figure out how to get that J distance...granted I am a chemist not a mathematician, but nevetheless I thought something this complicated would make photography stressfull, not fun.....

[kelly_flanigan1]

Bill; Here the Billboard minimum spacing is 1500 feet; thus our local Billboard guy wants me to get him a laser rangerfinder that goes to 2000 feet; and <B>reads in feet.</b>....<BR><BR>There are now several Laser rangefinders that go to 600 yards ++; but they only readout in yards......<BR><br> The divide by three "is too much trouble" !!!!! (his direct quote) <BR><br>I guess he probably wont be wandering into the DOF minefield here!

[jerry2]

Jorge.... One, does hyperfocal distance apply to large format when using tilt?

 

My vote is for..... not in the conventional method we are used to using it. However, it is still neccessary at times for calculations involving tilt, such as Merklinger long version.

 

> I would like to see a show of hands, I think this would be more useful to Alex than the discussion that has been done so far.

 

I guess we should have started that new thread when we first suggested it, oh well, it ran its course, sorry Alex.

 

> Two, how come Adams, Weston, Caponigro, Sexton, manage to get such great images without all those gadgets like range finder, inclinometer, etc?

 

That's an easy one. For starters, most landscape shots are taken without movements. When movements are required, they often are quite simple as the example I stated above, no gadgets required, very simple math in your head, or quick trial and error on the gg, 30 seconds max. The complex tilt scenes (which pertains to all the above discussion) can be handled many ways.... they can be bracketed to increase liklihood of success. They can be worked on the gg for quite awhile until success is had. They can abandon tilt and squeeze all the DOF from conventional DOF tables. They can have a great image that has limited enlargement potential. etc. etc.... Making great images has virtualy nothing to do with tilt math. This is like asking how anyone traveled before automobiles were invented. People make the best of what is available to them. That does not mean more accurate or faster methods are not beneficial. Like everything else in the world, one generation grows off the next. Techniques, tools and methods become refined and improved through the years. Tilt math is one of the few areas that seem 150 years behind schedule! :-)

 

Kelly, DMG makes one that goes up to 2000 ft, and reads in feet. I know they did a few years ago. I also do not like the ones that read out in yards. They are quite often targeted to golfers and hunters. The only thing I do not like about my DMG is the read out is not visible through the rangefinder.

[pete_andrews]

Martin: The optical laws associated with a 'box camera', as you put it, are no different from those that control the DoF of an inclined focal plane. There is ONE SET of rules of physical optics which govern ALL focusing, whether the camera is a fixed lens box camera, or a 20x16 with all the movements.<p>My diagram is absolutely correct by all the recognised rules of optics. It's Merklinger's oversimplification which is wrong.<p>BTW. How do you suggest I show a linear graph which goes from 1 metre to infinity Martin? Do you have a computer monitor that's infinitely wide? Be sensible.<p>When you start to think for yourself, and are able to do more than just quote Mr Merklinger, then please come back with some real and intelligent thoughts on this subject.<p>Merklinger did NOT invent the concept of intercepting focal planes, and simply being able to show how a lever works is no proof of anything.<br>Even the formula given for the distance 'J' is incorrect - it should be f/Tan(a). This is a small but significant difference. Otherwise the focal plane doesn't lie exactly horizontal when the lens node is brought to 'f' from the centre of the film plane. f/Sin(a) gives the diagonal distance from the lens node to the Scheimpflug intersection line at infinity, whereas the value J is the vertical distance from the node to Merklinger's 'hinge point'. Therefore J must equal f/Tan(a), from simple trigonometry.<br>If you take the extreme case of a=90 degrees, then this still gives us a value of J = f, if we divide f by the sine of the angle, whereas the correct value is obviously 0 ( f/infinity ).<br>So much for Merklinger being a brilliant mathematician!<p>Something else to ponder: Can an inclined plane of focus be really flat?<br>Since the change of focus across the film plane is caused by a simple angular offset between the film plane and the lens's focal plane, then it follows that the change of effective lens extension varies linearly across the film. Now a given change of extension (delta u) has more effect on the focused subject distance (delta v), when the lens is close to infinity focus, than it does when the lens is focused close-up.<br>It follows, as night follows day, that the plane of sharp focus CANNOT be a linear slope, but MUST be curved. Think about it: A 1 mm shift in lens extension from infinty makes a huge change to the focused distance (from infinity to 22 metres with a 150 mm lens), but that same change, with the lens now focused at 22 metres only shifts the focus by another 11 metres.<br>Consider a lens focal plane, tilted such that there is a 2mm wedge between it and the film plane, across the film length (about 1 degree of tilt or swing). With the focus at infinty on one edge of the film, the centre of the film will focus at 22 metres, and the other edge of the film will focus at 11 metres. Now that doesn't really form a flat focal plane, now does it? And it becomes even more non-linear with increasing angle between the lens and the film, as we attempt to lower the angle of the plane of focus.<p>Come on!<br>Think guys, think!<br>Don't just take 'Murky's' word for everything.

[WAn]

For sake of simplicity lets consider the vertical cross section of the whole picture (like in the demo picture above), so we have to speak about focus line instead of focus plane.

Gaussian lens equation:

1/v + 1/u = 1/f

u � distance in space of objects (from lens to object)

v � distance in space of images (from lens to film)

f � focal length

Lets consider a line in the space of objects. A line is fully determined by 2 points; say P1 with coordinates (X1, Y1) and P2 (X2, Y2). The equation of that straight line is

A*x+B*y = C.

(A, B, C can be found if X1, X2, Y1, Y2 are given)

 

The equation maps P1(X1, Y1) and P2(X2, Y2) to G1(x1, y1) and G2(x2, y2): the x1, x2, y1, y2 can be found also. The straight line that contains G1 and G2 has the same form:

K*x+M*y = N

The coefficients K, M, N also can be found.

 

Now lets consider a THIRD point P3 (X3, Y3) that is located anywhere in the first line, i.e. its coordinates satisfy the equation

A*X3 + B*Y3 = C.

We will prove the lens equation maps a line to a line if we show, that the image of P3, --- say G3 (x3, y3) --- does satisfy the second line equation:

K*x3+M*y3 = N

 

It is really boring to post all the algebra here.

I hope everybody who is interested can do it.

[huw_evans2]

Pete, again I won't comment on the Merklinger stuff because I still haven't read it, but in your final paragraph you are now effectively claiming that the whole Scheimpflug thing has been wrong all along. Your argument for this is nothing more than arm waving, and I would have expected you to know better! You need to sit down with some paper, a pencil, and the thin lens equation and do some basic coordinate geometry. Planes do transform to planes.

 

We are not talking about some deep, arcane, and complex mathematics here - I had a question involving manipulation of that equation in my O-level mathematics paper when I was 15 years old! Scheimpflug is not in doubt.

 

Of course, if you want to get into the realms of considering the differences between realistic thick lenses and the idealized notion we tend to rely on, then perhaps things are different, and I wish you the best of luck. I think the thin lens mathematics is close enough for all practical purposes.

 

Bill, just one point - I think you are mistaken if you think that most LF landscape work is done without movements. Probably the single most common set-up in landscape involves front (or possibly rear) tilt just to get things sharp from the foreground out to the horizon. Not complex, maybe, but still movements.

[WAn]

Forgot to mention:

The lens equation maps only x-coordinates. The y-coordinates can be found from the condition, that the line "point---its image" crosses the lens center: i.e.

 

y/Y = x/X, i=1,2,3.

 

And a note about imaginary contradiction "theory vs. practice": nobody asks to perform a math in field; the simple results obtained from the math that have been done in advance can be applied in the field. And an overall understanding never hurts, even in the field. And nothing is better for practice than a good theory!

[huw_evans2]

Jorge, yes certainly hyperfocal focussing 'applies' when using tilt. no matter what you do with your lens, film, and focus planes there are always DoF limits (as determined by a given positive CoC), and there will always be an optimal placement for the PSF and appropriate choice of aperture to get those limit planes where you want them. The question is not so much whether it applies as how to figure it out.

[MTC Photography]

Pete wrote:

"My diagram is absolutely correct by all the recognised rules of optics. It's Merklinger's oversimplification which is wrong"<p>

 

 

Do youa agree that three parallel DOF planes when lens is not tilted

become three intestecting planes, and not two curved planes + one

plane ?

<p>

I think Huw probably pointed out the problem of your diagram: you did not use the correct object distance: which is NOT the length of the line connecting the center of lens to the object, it must mulitplied by the cosine of the angle between the said line and the optical axis. <p>

[MTC Photography]

Pete wrote:

 

"It follows, as night follows day, that the plane of sharp focus CANNOT be a linear slope, but MUST be curved."

 

This it Pete rule of LF replacing Scheimpflug.

[ellis_vener_photography]

<I>"No issue is so small that it can't be blown out of

proportion."</I><P> - Stuart Hughes

[squareframe]

as fascinating as this may be, an hour with a set of wooden blocks and camera, positioned strategically, will shine more illumination than this glowing thread.

 

for sale:

 

Linhof Technikardan TK45S, mint, never used.

 

Rodenstock and HP21 calculators, serviceable but severely worn.

[pete_andrews]

<i>"you did not use the correct object distance: which is NOT the length of the line connecting the center of lens to the object, it must mulitplied by the cosine of the angle between the said line and the optical axis."</i> - Huh?<br>Nonsense! That's only true if the lens doesn't have a flat field to start with.<br>Consider: There is absolutely no difference between tilting the lens plane, and tilting the film plane; apart from a difference in the aim of the camera.<br>If you consider the lens panel and the plane of focus to stay vertical, and the filmplane to be tilted, then you can more readily see that the conventional conjugate focii formula of 1/f = 1/v + 1/u holds true for every point on the film surface. If you compute many of those points (not just two, Andrey) you can see that a tilted plane of focus is not linear across the film, and nor is the DoF.<p>Is anyone disputing that a tilt of 1 degree on a 5x4 camera focuses one long edge of the film at 11 metres, and the other edge at infinity with the centre focused at 22 metres, (or at 3 metres and 4 metres, respectively with a mid focus of 3.4 metres)? It's easy enough to check practically, as I spent (wasted) some of my weekend doing.<p>Martin: Moving the plane of focus is NOT the same as defining the limits of DoF. This is the fallacy that Merklinger perpetuates with his peculiar and simplistic outlook on DoF. It is an approximation which only works over a very limited focusing range, but it is not an accurate mathematical model of optical behaviour.<p>Huw: Arm waving?<br>To whom?<br>Most people seem so blinkered and hoodwinked by Merklinger that I'm surprised they notice anything moving at all, outside of a very narrow field of vision. ;^)

[MTC Photography]

pete wrote:

""you did not use the correct object distance: which is NOT the length of the line connecting the center of lens to the object, it must mulitplied by the cosine of the angle between the said line and the optical axis." - Huh?

Nonsense! That's only true if the lens doesn't have a flat field to start with."

 

<p> Your are really confused.

<p> With your way of calculation , a flat field will form a curved

image,, hmm, that is what you got so far

<p> For flat field lens, D must be multiplied by the cosine

 

 

<pre>

 

 

 

* P2

*

*

I1 ***** * *()* * * * P1

*

*

I2 *

 

 

 

 

 

</pre>

 

<p> In this diagram, P1, P2 are in the same vertical plane

 

<p>

<p> For flat field lens, image of I1, I2 are on the same

vertical plane

 

<p> The object distance of P1, is the same as P2

 

<p> Image distance is also the same (along optical axis)

 

<p> A very simple question for pete

<p> In 35mm camera, do you think the object distance at the edge

of viewfinder is the same as that object in the center ? Or

do you think the object at edge has greater object distance than the

center object ?

[jorge_gasteazoro5]

<i>That's an easy one. For starters, most landscape shots are taken without movements. When movements are required, they often are quite simple as the example I stated above, no gadgets required, very simple math in your head, or quick trial and error on the gg, 30 seconds max. The complex tilt scenes (which pertains to all the above discussion) can be handled many ways.... they can be bracketed to increase liklihood of success. They can be worked on the gg for quite awhile until success is had. They can abandon tilt and squeeze all the DOF from conventional DOF tables. They can have a great image that has limited enlargement potential. etc. etc.... Making great images has virtualy nothing to do with tilt math. This is like asking how anyone traveled before automobiles were invented. People make the best of what is available to them. That does not mean more accurate or faster methods are not beneficial. Like everything else in the world, one generation grows off the next. Techniques, tools and methods become refined and improved through the years. Tilt math is one of the few areas that seem 150 years behind schedule! :-) </i><p>

Bill Thank You!!!!!! This is what I was wondering. Most of the discussion here has been of 200 feet tall trees and billboards 2000 feet away etc, and I was thing well jeezz everytime I am on the field I only need a few degrees here and there for tilt, what is all the fuzz about? Granted as you mention more advanced techniques evolve from the past, but if you ask me forget Merklinger's and buy the little Rodenstock gizmo....and save yourself a big headache.<p>

[huw_evans2]

I'm sorry Pete, but I can only echo what Martin has said - '<i>you are really confused</i>'. The distances are measured <i>perpendicularly to the lens plane</i>, and hence the cosine factor.

<br><br>

Your weekend example could be expressed a bit more clearly, but I can't see that there is necessarily anything wrong with your measurements - you just haven't demonstrated that the transformed plane of focus is anything other than a plane, which is what you now seem to be disputing. That it <i>is</i> a plane is a straightforward corollary of the thin lens equation, and for those who don't like doing the mathematics it is trivial to verify experimentally, and photographers have been doing just that for generations.

[pete_andrews]

Huw: Then the proof is easy. Drag out your camera like I did, fit a 150mm lens, and set a 1 degree tilt or swing on it. Then measure the focus at the extremes of field, along with the central focus.<p>Sorry Martin, but you won't be able to verify anything with a minox or 35mm camera.<p>The focusing distance to the edge of the field is a complete red-herring, and varies with the part of the lens field used. You'll throw anything into the mix to confuse the issue, won't you?<br>Anyway, I deliberately picked a small angle of tilt for my example, so that things like that became a non-issue. Do some of the calculation for yourself for a change. Throw in your cosine 'correction' - it'll make very little difference - the field and the DoF still comes out curved.