General Discussions and Small Talk
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BrianTyler

Image Sharpness Problems

You can easily test your camera and lens for sharpness using a white piece of paper (use a good quality printer paper)
Draw a skinny line with a pencil on the paper.
Photograph it using normal day light, no flash.
Camera on a tripod, vibration reduction set to off.
Open the image using Imager.
I created Imager for my students and it can be downloaded from my web site for free.
http://www.MyCIGroup.com then navigate to Imager.
It is not great looking software but serves the purpose for research!
Open the image and save it to text file.
Open the text file using EXCEL.
Scroll down until you find the Grayscale section. For each pixel there is one number listed.
Find the transition from white to black. It should look something like 175 175 175 70 60 55 55 55 55
This may vary in numbers, which is not important. It all depends on how white the paper is and how dark the line is.
Again, this is not important.
Count the number of pixels it took to transition from white to black. In my example above it took 3 pixels.
This transition is what humans interpret as sharpness or in focus. If it takes 5, 6, 7 pixels to transition, then the image is less sharp. Measure it.
Repeat the test by taking the camera out of autofocus, change aperture, etc. You will soon understand your camera.
A standard 35 mm camera will not transition in 1 pixel, it should be 2 to 3 pixels.

A couple of things to consider, keep the distance just far enough to allow the camera to focus properly. I would say 6 feet. Experiment with zoom settings but don't try to macro the object. That defeats the purpose of the test.
08.05.15, 04:42
You can easily test your camera and lens for sharpness using a white piece of paper (use a good quality printer paper)
Draw a skinny line with a pencil on the paper.
Photograph it using normal day light, no flash.
Camera on a tripod, vibration reduction set to off.
Open the image using Imager.
I created Imager for my students and it can be downloaded from my web site for free.
http://www.MyCIGroup.com then navigate to Imager.
It is not great looking software but serves the purpose for research!
Open the image and save it to text file.
Open the text file using EXCEL.
Scroll down until you find the Grayscale section. For each pixel there is one number listed.
Find the transition from white to black. It should look something like 175 175 175 70 60 55 55 55 55
This may vary in numbers, which is not important. It all depends on how white the paper is and how dark the line is.
Again, this is not important.
Count the number of pixels it took to transition from white to black. In my example above it took 3 pixels.
This transition is what humans interpret as sharpness or in focus. If it takes 5, 6, 7 pixels to transition, then the image is less sharp. Measure it.
Repeat the test by taking the camera out of autofocus, change aperture, etc. You will soon understand your camera.
A standard 35 mm camera will not transition in 1 pixel, it should be 2 to 3 pixels.

A couple of things to consider, keep the distance just far enough to allow the camera to focus properly. I would say 6 feet. Experiment with zoom settings but don't try to macro the object. That defeats the purpose of the test.
311 clicks
Ken Piros

February Monthly Theme – Something around the house

25.02.15, 05:04
702 clicks
WildeMan

I need to know what the right thing to do is.

Hi everyone:

I recently published (self) a book of my photos on Amazon. It is called Urban Dada, and it is my vision of street art/posters/ephemera as abstract collage art.

My question is this: I would like to send copies of my book to various experts in the genre to get their perspective and (hopefully) recognition. Is this a good idea? Is this how it is "done" professionally?

Or should I try to win a contest or show in a gallery first????? (presuming I succeed at those).

I also wondered if it was more appropriate to send them actual hard copies of the book or email them a PDF of the whole book. I know nothing about photography promotions or etiquette.

Perhaps you know of a way that is more effective/acceptable/ commonly done?

Thanks!

J
306 clicks
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