Resolution Chart/Targets

Grif

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Any way to get a reasonable resolution chart to check out a lens at say 1 and 10 meters without spending a pile of money? I wouldn't mind spending $30 or so, but I'm not in need of a really hi dollar one. Vertical and horizontal lines, circles, line pairs. Mostly a basic overview of lens behavior?

I think I've still got enough stuff to build one good enough by hand from the drafting days if I really need to. The resolution side would likely not get done if I need to DIY it.
 

ic-racer

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I think there are some on the internet you can download and print out. Search for USAF test chart. Dead Link Removed
 
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Grif

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Ok,,, Now I"ve got the same resolution target I used to use in the microfilm lab in the very early 70's. Now for something with some straight lines and corners?
 

Photo Engineer

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Well, the original site does not work even with refresh. Copy and paste works to give the same chart in all references here.

The thing that I did not post until I could see them all is the fact that these are all one "polarity". You must have a negative and a positive set of these to run a test on both image "bloom" and image "fill in". You can only do this with 2 charts. I have both of these in 4x5 and 35mm versions. I find them very useful. The charts in 35mm size are available from Edmund Scientific but are quite pricey.

BTW, most charts like this are intended for contact printing rather than being photographed using a camera, but a large size version of the charts in your references can be used to determine some level of sharpness. However, to do it accurately, you need a set exposed in-camera and a set exposed from the originals directly onto the print material so that you can compare them. In such a test you would then have 4 final prints.

PE
 

Q.G.

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Bloom and fill in are the same thing: spread.
So a negative version will not be able to reveal anything a positive version would not show already.

Charts like this are indeed intended to be photographed using a lens. You already have a comparison for your lens test in the chart itself.
But unless you are examining the aerial image produced by the lens, you will indeed be testing the emulsion of the film too. If you print the negative before examining, you'll be testing the emulsion of the print as well. Plus the loss created in the transferral from negative to print (whether it be by contact or projection).

These charts therefore are of very limited practical use, unless you put the microsope on the optical bench to examine the aerial image produced by the lens.
 

Nicholas Lindan

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I don't have many pictures where I look at it and wince, thinking the lens really screwed that one up.

* * *

When I test I read the resolution target results by examining the print. I am only interested in what can be produced in a print I can hang on the wall.

Separating the resolutions of the lenses, film and paper is interesting for lens, film and paper designers but not of much practical use for a photographer.

When looked at as a system the resolution of the camera lens isn't really all that important. Using Tech Pan, a tripod, a critical magnifier, bracketing the focus, using the lens' optimum aperture, and doing all the rest one can do, I find a really good lens - a Sumicron or Micro Nikkor - can produce a usable 80 lp/mm on a print. A $100 consumer zoom can't do much better than 60. Without looking at the prints with a microscope it is hard to see much difference between the two lenses.

Shooting hand held, wide open, at medium/low shutter speeds, on high speed film or using an 'acutance developer' degrades the system performance to such an extent that lens performance is largely irrelevant. Which is as it should be - it's the subject matter that makes the picture significant, not the lens.
 

Photo Engineer

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Blooom and fill are not the same. I won't relate the details of this, but it is related to the mass of the dark (or light) surround that creates edge effects or overwhelms them, particularly as the subject matter becomes smaller. This is, in some ways, related to macro and micro contrast.

As for making prints directly from the charts, well, you measure the response of the printing process alone (enlarger or contact - and the paper). If you photograph a chart and then print it, you measure the camera lens, flare and film. That print will be the overall system response.

PE
 

tkamiya

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When I need to do some comparison testing, I just use some fresh and crisp dollar bills. Take out a form core board, tape one dollar bill in the center, one at each corner. It has enough font sizes for good reference, prints are crisp and size and quality are very uniform. Enough for my purpose....
 

RalphLambrecht

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ic-racer said:
I think there are some on the internet you can download and print out. Search for USAF test chart. Dead Link Removed
Click to expand...

The link did not work for me either, but here is another alternative:

Dead Link Removed

You can print these yourself, but depending on your print quality, you may want to use a distance, which makes you independent of the smallest bars. High-resolution alternatives can be purchased for little money from Edmund Scientific.
 
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Grif

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All the sites worked fine for me, I really appreciate the efforts. I'm using box stock IE 8 and xp fully patched BTW, and did not need to do a refresh or anything. Your mileages obviously varied ;-)

Boy,,, I was on the Edmond Sci site,,, inexpensive is something I didn't even think about when looking at most of their prices. I'll go check again.


quote: "Shooting hand held, wide open, at medium/low shutter speeds, on high speed film or using an 'acutance developer' degrades the system performance to such an extent that lens performance is largely irrelevant. Which is as it should be"

A little out of context for sure,,, but I think I'd add,,, "for me" (actually for you), at the end of your sentence. Different folks, different directions in the hobby. I enjoy the technical side of the hobby, and have just begun (like since I joined apug), to appreciate a little grain visible in the final print. My usual combination in the 70's was Pan X and microdol x 1:3 with an ASA of less than 25. For some folks, being able to previsualize perspective and a particular lens barrel distortion or bow is totally irrelivent to the picture. For me,,, its an important (and fun) part of the process,,, unless I'm just snapshotting the 6 year old "alternative process" pocket thing which does any number of bad things in the corners. (and in the middle for that matter).
 
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Grif

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snip: "A little out of context for sure,,, but I think I'd add..."

Sorry about that,,, not your comment out of context,,, it was out of context after I snipped it. I think I understood what I tried to write, but when I read what I wrote wasn't what I meant to write???
 

Q.G.

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Both however are the result of one and the same thing.
If you have a measure of that (spread), you'll know about both bloom and fill.


The OP asked about a way to test a lens.
 

RalphLambrecht

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Grif

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Hey,,, good job. I finally went thru most of them,
Dead Link Removed

Is also an affordable item I'll likely add to the order with the small resoulution target.
 

Q.G.

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Resolution represented by the lines on the target is a function of distance and focal length (i.e. scale).
So one target can serve for both low and high resolution tests, just by altering distance.
 

Photo Engineer

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Q.G. said:
Both however are the result of one and the same thing.
If you have a measure of that (spread), you'll know about both bloom and fill.



The OP asked about a way to test a lens.
Click to expand...

I answered the OP with a complete description of testing.

As for fill and spread they are aspects of the same thing but are manifested differently as a function of line width and "polarity" of the original. You would see that if you ran the tests.

PE
 

RalphLambrecht

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Grif said:
Hey,,, good job. I finally went thru most of them,
Dead Link Removed

Is also an affordable item I'll likely add to the order with the small resoulution target.
Click to expand...

Yes, this one includes the resolution table, which you need to quantify your results by multiplying it with the inverse of your imaging scale. You'll also find the table here:

Dead Link Removed
 
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Grif

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Fill/Spread Question-Comments


If I understand correctly,,, fill/spread are the terms for diffusion on the lens, and diffusion at the enlarger? Light spreads into the shadows,,, or shadow fills into the hilights?

I think that's when I first got the difference, but I sure don't remember them being referred to as fill and spread back before grey hair. I just remember going, wow, that didn't turn out like I thought in the dark room one day.
 

Q.G.

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Dark can't and doesn't spread, so the effects fill and bloom are both caused by light spreading.
Bloom is light creating a fuzzy edge between bright and dark areas where there should be a sharp one. Fill is where the bloom of adjacent bright areas touch, filling in the dark bit inbetween.

The spread is a function of how a lens transmits light. (Flare is something different.)
Or of how light is diffused inside an emulsion.
To test a lens alone, you have to look at the aerial image it produces of a test target.
If you want to test the effect of the film too, you have to examine the recorded image on film (which has to be developed before you can see it, so you will be seeing the effect of development too).
If you want to test the effect of the paper, [etc.]
 
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