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percepts
8-Jun-2009, 19:41
Since the question has arisen in the V700 thread about how much resolution can be had on film, I have copied an old article from Zeiss Camera Lens news about how to determine on film resolution in the real world as follows:



How To Determine the Resolution Actually Reached in a Photograph - A Practial Example
Let us assume we are about to take a photo of a landscape. Somewhere there is a farm. And a wooden fence. Its white painted vertical slats, each about two inches wide (which we will convert to 50 mm) and spaced with about two inches distance to the next slat (we may have to go there and measure these values), stand clear against some darker background.
This wooden fence represents a structure of dark and bright lines similar to those in resolution test targets. Let us further assume that we are using a Carl Zeiss 50 mm Planar standard lens and a Contax SLR camera. The fence may be a quarter of a mile away (as a map can tell us or a binocular with a distance measuring device).
Now, let’s make a rough calculation of the resolving task facing our imaging system:
From a quarter mile distance, which is about 400 meters, the reduction ratio, let’s call it “r”, for the fence to be imaged on film with the 50 mm lens, is as follows:
r = focal length divided by object distance, expressed in the same unit. This gives: 50 millimeters /400 x 1000 for a ratio of 1/8000.
So the original subject, the farm and the fence, and every detail will appear at 1/8000th of its original size in the negative (or slide, whichever you prefer). One slat plus one space, both representing one line pair in the original subject, are 4 inches wide. This equals roughly 100 millimeters. Reduced by the reduction ratio of 1/8000 it should appear on film with this width: 100 millimeters ⁄ 8000 = 1/80 of a millimeter. So 80 fit into 1 millimeter, which means, we are about to resolve 80 line pairs per millimeter.
Can our imaging system handle this task? For a Zeiss Planar in a Contax camera and any modern 100 ISO film, 80 line pairs per mm is an easy challenge, if we focus precisely and avoid unwanted vibrations (by using a good tripod). So let’s go ahead and take the picture. The fence should be well resolved in our photo.
Or, the other way round: If we took the photo and later found the fence resolved, then we knew we did achieve at least 80 line pairs per millimeter.


So now you know why white picket fences are so popular in America. Purely because photographers need a subject to make calculations about film resolution...

ignatiusjk
11-Jun-2009, 14:37
I'd like to help you but I didn't understand any of that post.

sanking
11-Jun-2009, 15:13
I'd like to help you but I didn't understand any of that post.

Maybe the answer to the question is that Paul Strand made some great images of white picket fences, and many of us would like to make great images like Strand, so voila, there is the white picket fence.

Sandy King

Bruce Barlow
11-Jun-2009, 17:17
Why does resolution matter?

sanking
11-Jun-2009, 21:54
Why does resolution matter?


Is this a serious question?

Sandy King

Bruce Barlow
12-Jun-2009, 04:40
Is this a serious question?

Sandy King

Yes, sorta. With modern materials, reasonably modern equipment, and adequate technique, I don't understand why I would care whether I have +/- 10 percent more resolution. It's the picture that matters. I mean, ohmigod, I enjoy using - gasp - 35mm. I like the pictures even though they don't appear to have the same quality as my LF stuff.

It seems overly technical without practical use or effect, at least for me. I need to worry where I'm standing when I make the picture.

venchka
12-Jun-2009, 07:48
Once upon a time I was in the zillion lp/mm camp. Lately I've been gravitating toward Bruce's position. Given the myriad things that can go wonderfully right or terribly wrong when I am making a photograph, extracting maximum resolution from the film seems like the last or maybe the next to last thing that I need to worry about.

I have miles to go before I get everything else right. Given the level of performance from modern, or even ancient, lenses and modern films and developers, I reckon there is adequate resolution present. Certainly more than my $150 scanner can find.

I just hope that I can find the right place to stand when I'm out tomorrow with a camera. If I get anything else right it will be a bonus.

Nathan Potter
12-Jun-2009, 08:06
For some, resolution matters. They are enamored with texture and it is central to their photographic statement. It is why many do large format photography. OTOH one can get carried away with an obsessive search for the ultimate in resolution and not see other wondrous images all around us. I think that is all Bruce is saying.

But I've had to paint too many picket fences to get too excited about photographing them. If I did images of such I would hope they do not get resolved in the film. :p

Nate Potter, Austin TX.

Bruce Watson
12-Jun-2009, 08:19
I need to worry where I'm standing when I make the picture.

This, to me, is the most important decision we make. If we screw this up, the rest doesn't matter.

That said, having good understanding of the technical underpinnings of photography in general and LF in particular are important. The craft side is nearly equally important, because without it we can't reliably realize the art that standing in the correct place allows us to create. IOW, the craft has to serve the art.

For me understanding the resolution thing is nice, an interesting puzzle, and somewhat useful in the field. But even if I know that I should shoot a particular lens at f/11 for best resolution, I'm going to shoot it at f/32 anyway because that's what I need at the time to make the photograph that I'm envisioning.

Ivan J. Eberle
12-Jun-2009, 08:25
Resolution matters to those of us selling images, in competition with others to
whom resolution matters.

venchka
12-Jun-2009, 08:34
Resolution matters to those of us selling images, in competition with others to
whom resolution matters.

That leaves me free to do whatever I please. I don't have to worry about sales. :D ;)

percepts
12-Jun-2009, 08:58
This, to me, is the most important decision we make. If we screw this up, the rest doesn't matter.

That said, having good understanding of the technical underpinnings of photography in general and LF in particular are important. The craft side is nearly equally important, because without it we can't reliably realize the art that standing in the correct place allows us to create. IOW, the craft has to serve the art.

For me understanding the resolution thing is nice, an interesting puzzle, and somewhat useful in the field. But even if I know that I should shoot a particular lens at f/11 for best resolution, I'm going to shoot it at f/32 anyway because that's what I need at the time to make the photograph that I'm envisioning.

The following are what a very good quality modern lens can achieve.



f-no. resolution (line pairs per millimeter)
45 35
32 50
22 70
16 100
11 140
8 200
5.6 280
4 400
2.8 560


And that is in the plane of focus. Off that plane but within the so called depth of field, those figures will drop by 50% and more. They also assume perfect film alignment, something rarely acheived in large format photography. And also assume zero camera vibration.

In other words there will be parts of your image achieving 50% or less of those figures meaning at f22 you can expect 4 to 6 enlargemnt max from a 4x5 neg exposed at f22 if you want very high print resolution. Get anything wrong, such as slightly misaligned enlarger and it will be less.

Difficult this large format photography isn't it. Mind you, because most of us never achieve these high standards, we accept lower ones without realising it could be much better. If only we paid attention to the technical aspects and applied them by doing something simple like aiming to expose at f8 whenever possible. That way we achieve much higher on film resolution which in turn gives us more room for error elsewhere in our process.

Thats why resolution is important. Just using 3 stops wider aperture makes a huge difference.

Bruce Watson
12-Jun-2009, 09:19
...meaning at f22 you can expect 4 to 6 enlargemnt max from a 4x5 neg exposed at f22 if you want very high print resolution.

The term "very high" is highly subjective. I've got a number of beautiful 10-12x enlargements that show amazing amounts of very sharp detail. Nice big 125 x 100 cm prints. I've had a lot of comments about how sharp they are, and never had a comment about them being soft in any way. These were all made between f/16 and f/32 with any of five different lenses.

Now it's true that they could be even sharper, but at the expense of things outside the exact plane of focus being even softer. Which would in general be a detriment to the print, which is why I chose the aperture I chose.

I'm not saying that resolution, sharpness, acutance, whatever you want to call it, isn't important. It is important. But it's not any more important than any of the other myriad parameters and decisions that go into making an LF photograph.

Resolution is but one parameter among many.


Difficult this large format photography isn't it.

You can make it as difficult as you like.

percepts
12-Jun-2009, 09:34
The term "very high" is highly subjective. I've got a number of beautiful 10-12x enlargements that show amazing amounts of very sharp detail. Nice big 125 x 100 cm prints. I've had a lot of comments about how sharp they are, and never had a comment about them being soft in any way. These were all made between f/16 and f/32 with any of five different lenses.

Now it's true that they could be even sharper, but at the expense of things outside the exact plane of focus being even softer. Which would in general be a detriment to the print, which is why I chose the aperture I chose.

I'm not saying that resolution, sharpness, acutance, whatever you want to call it, isn't important. It is important. But it's not any more important than any of the other myriad parameters and decisions that go into making an LF photograph.

Resolution is but one parameter among many.



You can make it as difficult as you like.

Correct, resolution is but one parameter. But many people here scan and they will quite happily expose at f22 or f32 and wonder why they don't get more than 2000 - 2500 spi in their scans. Answer, simply because it wasn't in the neg to start with which is why I posted the picket fence method of real world neg resolution testing. So people can do a very simple practical test to see how good their system really is.
All you need to do is to take two images. One at f22 and one at f8 or f5.6 and the difference is resolution immediately obvious just from looking at the negative.

Dan Fromm
12-Jun-2009, 10:04
The following are what a very good quality modern lens can achieve.



f-no. resolution (line pairs per millimeter)
45 35
32 50
22 70
16 100
11 140
8 200
5.6 280
4 400
2.8 560
Percepts, you're confusing the theoretical limits set by diffraction alone with the actual limits set by other aberrations and diffraction. I own some lenses that are in fact diffraction limited, but not wide open and only over small fields.

As a practical matter, we all do very well to resolve as much as 60 lp/mm on film or sensor. No real lens comed close to the limits you've given. Don't even think of telling me about the very expensive lenses made for aerial cameras. I have a number of them, some quite fast, and none is particularly good wide open with normal ordinary white light.

This is why getting a good big print requires a good big negative.

Cheers,

Dan

percepts
12-Jun-2009, 10:30
Percepts, you're confusing the theoretical limits set by diffraction alone with the actual limits set by other aberrations and diffraction. I own some lenses that are in fact diffraction limited, but not wide open and only over small fields.

As a practical matter, we all do very well to resolve as much as 60 lp/mm on film or sensor. No real lens comed close to the limits you've given. Don't even think of telling me about the very expensive lenses made for aerial cameras. I have a number of them, some quite fast, and none is particularly good wide open with normal ordinary white light.

This is why getting a good big print requires a good big negative.

Cheers,

Dan

Not quite, the theoretical limits give more resolution than that. The figures I gave are from Zeiss and have been achieved on 35mm cameras. But yes I agree that with large format lenses, particularly when wide open, you can start to see a fall off in resolution from the figures I posted due to other lens aberations. And that makes it even more difficult to achieve a 20x16 print that is of the highest quality possible.
I know many aren't worried about it but many also assume that because they are using 200 lp/mm film, that will improve their resolution. It won't unless they are technically savvy enough to utilise the films capabilities. Again, that is another reason for doing the simple parctical test of photographing a white picket fence from a known distance. You actually get to see what is really happening. And to also begin to understand that a piece of 4x5 or bigger film flopping about in a film holder really doesn't help things.

ic-racer
12-Jun-2009, 11:23
The basics of photography. You control timing, framing, light-dark and contrast, and focus (or sharpness).

Greg Blank
12-Jun-2009, 12:39
Resolution matters to those of us selling images, in competition with others to
whom resolution matters.

Resolution "Always matters" How one applies it is alway a personal choice. Soft focus can be just as lust worthy as hard line and biting.

Gb 6-12-09

Dan Fromm
12-Jun-2009, 13:27
percepts wrote "The figures I gave are from Zeiss and have been achieved on 35mm cameras."

Please give a citation. The numbers you quote are uncannily close to the Rayleigh limit.

percepts
12-Jun-2009, 14:19
http://www.zeiss.de/C12567A8003B58B9/Contents-Frame/15C75F926592E5C1C1256CED0054968D

Camera lens news No 2:

last section "Resolution of camera lenses – Where are the limits and why?"

read the full section as they say they can reach the limits of colour films upto 200 lp/mm. At least that seems to be what they are saying. And if you take their example of a 4mm object at 400 meters photographed on 100mm lens at f5.6 and do the maths as in the first post of this thread, then thre result is 500 lp/mm unless I got the maths wrong. I interpret them as saying they reach the film limit cos obviously the film isn't capable of that but the object resolves.

Rayleigh limit or no, they say their lenses are capable and who am I to argue with zeiss.

Dan Fromm
12-Jun-2009, 15:01
Thanks for the citation, do read the piece again.

It says that resolutions in the table you presented are theoretical and can't be attained by real lenses. Also that the best color films can resolve 140 lp/mm and that some Zeiss lenses deliver that resolution on these films at f/5.6 and f/8.

And it says "Objects of 4 millimeter in size (approximately 1/6 of an inch) have been imaged from almost 400 meters distance (more than 1.000 feet) with a 100 mm Carl Zeiss Makro-Planar lens at f/5.6 and a Contax RTS III 35 mm SLR camera featuring the
unique Contax vacuum pressure plate." I'm sorry, but this isn't at all the same as separating two objects 4 mm apart 400 m away. Resolution is about separating objects, not about imaging a single object.

Please think more about what resolution means and why we measure it in lp/mm or cycles/mm. If you want to be astronomical, think about the difference between capturing an image of a single star and seeing two stars as two stars and not a single blob of light.

If you want to see a newer, grander claim that still doesn't attain the levels you gave, see http://www.zeiss.de/C12567A8003B58B9/Contents-Frame/15C75F926592E5C1C1256CED0054968D . Camera Lens News #24.

percepts
12-Jun-2009, 15:18
Well without getting into splitting hairs, it did say ektar 200 lp/mm and I take the point that resolution is not the same as a single object. But getting back to the original point, and as I said, you can expect only 70 lp/mm or less on 4x5 film at f22. i.e. far less than people such as myself thought until I started doing some reading.
And that is why resolution is important. If you want fine detail in a print then you better pay attention to resolution.

Now I better get myself one of those 400 lp/mm lenses...:D

Dan Fromm
12-Jun-2009, 15:30
Nope, if you want fine detail in a large print you need to start from a large negative. If the goal is 8 lp/mm in the print -- some people here claim 5 lp/mm is good enough; I suspect their visual acuity is going -- then resolution on film has to be somewhat greater than 8 * enlargement. Practically speaking, the results of enlarging film more than 10 times won't bear close scrutiny. Same goes for the sensors in digital cameras.

Do you remember the hoopla about H&W Control Film (another way of spelling Agfa Copex) and H&W Control Developer (another POTA developer, I think)? The leicanuts who went really gaga over Control film/developer shot hand-held, thereby pissing away all of its possible advantages.

400 lp/mm lenses? Not that cover very much. I have a useless little 100/2.8 Era-7 that Russian sources claim will beat 400 lp/mm wide open with monochromatic light. It covers rather less than nominal 6x6. My neighbor C. Barringer has a heap of Zeiss Oberkochen stepper lenses that will beat 400. Tiny coverage, short back focus, huge and heavy. He has a stack of them, nicely boxed, whose job is to keep his garage's back wall from falling over.

If you want good big prints, move up in format and improve your technique. Or stay where you are and improve your technique.

Or wake up and realize that a strong image will usually please even though not as sharp as you'd like.

SAShruby
12-Jun-2009, 15:56
IMHO I believe it could be important to know what your equipment is capable to achieve with respect to best resolution, however it's not important to achieve highest resolution with each photograph you're taking.

Bruce Barlow
13-Jun-2009, 04:21
Fred Picker used to say that a good exercise is to make and print the same picture with 35mm, 4x5 and 8x10 at the same size and compare them. Now there's a practical exercise to actually see what resolution and grain are doing for or against you. I've done it, making 8x10 prints b'cuz I can't enlarge 8x10.

Interesting results, and no, I won't tell.

Brian Ellis
13-Jun-2009, 09:15
Fred Picker used to say that a good exercise is to make and print the same picture with 35mm, 4x5 and 8x10 at the same size and compare them. Now there's a practical exercise to actually see what resolution and grain are doing for or against you. I've done it, making 8x10 prints b'cuz I can't enlarge 8x10.

Interesting results, and no, I won't tell.

I think Charles Cramer does this in some of his workshops. I haven't attended any but I've read about them. I'm not sure why you're reluctant to give away the results, they're not surprising if what I've read is correct. The bigger the negative the better the results (technically that is).

Bruce Barlow
13-Jun-2009, 14:11
I think Charles Cramer does this in some of his workshops. I haven't attended any but I've read about them. I'm not sure why you're reluctant to give away the results, they're not surprising if what I've read is correct. The bigger the negative the better the results (technically that is).

I'm reluctant because:

1. People should actually do this for themselves, unless they're afraid of actually learning something. They might even learn things unrelated to the actual exercise.

2. It's clear to me that you haven't done it, based on your speculation about the results.

Let's not be lazy now, folks. (My, am I grumpy these days!)

RichardRitter
13-Jun-2009, 14:35
Fred Picker used to say that a good exercise is to make and print the same picture with 35mm, 4x5 and 8x10 at the same size and compare them. Now there's a practical exercise to actually see what resolution and grain are doing for or against you. I've done it, making 8x10 prints b'cuz I can't enlarge 8x10.

Interesting results, and no, I won't tell.

He would also tell you to photograph a white building with pealing paint as part of the test.

Brian Ellis
14-Jun-2009, 08:02
I'm reluctant because:

1. People should actually do this for themselves, unless they're afraid of actually learning something. They might even learn things unrelated to the actual exercise.

2. It's clear to me that you haven't done it, based on your speculation about the results.

Let's not be lazy now, folks. (My, am I grumpy these days!)

No, I haven't done it. I thought it was clear that I based my statement on something I read about demonstrations done in Charles Cramer's workshop, which I said I hadn't attended.

I don't think most of us here are afraid of learning something, nor are most of us lazy. Unfortunately I no longer have a 35mm camera or a medium format camera or an 8x10 camera so I'm unable to do the testing myself. Others here are probably in a similar situation. I'd certainly be interested in knowing the results of your testing, especially if I'm wrong in what I thought I remembered reading from Charles Cramer's workshop. I imagine others would also be interested. But if you want to keep the results of your testing a secret that's certainly your right.

Athiril
18-Jun-2009, 03:13
Thanks for the citation, do read the piece again.

It says that resolutions in the table you presented are theoretical and can't be attained by real lenses. Also that the best color films can resolve 140 lp/mm and that some Zeiss lenses deliver that resolution on these films at f/5.6 and f/8.

And it says "Objects of 4 millimeter in size (approximately 1/6 of an inch) have been imaged from almost 400 meters distance (more than 1.000 feet) with a 100 mm Carl Zeiss Makro-Planar lens at f/5.6 and a Contax RTS III 35 mm SLR camera featuring the
unique Contax vacuum pressure plate." I'm sorry, but this isn't at all the same as separating two objects 4 mm apart 400 m away. Resolution is about separating objects, not about imaging a single object.

Please think more about what resolution means and why we measure it in lp/mm or cycles/mm. If you want to be astronomical, think about the difference between capturing an image of a single star and seeing two stars as two stars and not a single blob of light.

If you want to see a newer, grander claim that still doesn't attain the levels you gave, see http://www.zeiss.de/C12567A8003B58B9/Contents-Frame/15C75F926592E5C1C1256CED0054968D . Camera Lens News #24.

140 lp/mm?

That's 1000:1 contrast ratio, the best colour gets 80 at 6:1 contrast, and there's also much much higher than 140 for 1000:1 in colour, such as the discontinued Royal Gold 25 which is astounding, or Provia and Velvia which go 160.

A lens which reaches or nearly reaches the resolution of the film or sensor means that the resolution of that lens at that f-stop is in fact much much higher than the film/sensor.

As kodak states (and there is formula for) if you want to achieve the full resolution of a system (either the full lens or full film resolution) then the other must be 3x higher, given the uniform nature of a bayer sensor and the random nature of film grain and grain sizes I dont think it'd be quite 3x for digital, but it'd still apply in some way.

Such high resolution lenses are also not unheard of, the Canon 70-200 f/4L IS (definately neither of the 2.8's nor the non-IS) and the Nikkor 24-70mm f/2.8 come to mind, as does the Canon G10 (at least on the wide end) which achieves it's full resolution of a staggering ~1.7 micron (sensor density) under optimum conditions - just so we're clear that would be a 114 megapixel sensor in Canon APS-C format, and 292 megapixel in 35mm format, if such a large size of such a fine process could actually be cut with any kind of yield at all and not all thrown away.

There are ridiculously high resolution films too - including one which measures up to that level and even surpasses it - Adox CMS 20, of course every step has to be optimal.

Again, its the right tool for the right job, there are many subjects wihch only require a small resolution - such as silhouettes against a sunset background, though of course that may benefit from granularity of larger formats which lend more effective resolution due to imaging area size, and can have smaller steps between each tone change as a side effect too.

Though there are obviously many applications where high resolution is the right tool too.