sippyjug104 Loc: Missouri

Well played, Sir. Very well played..! One should know that a pixel is quantity and it is dimensionless. A 24mp APS-C sensor and a 24mp Full Frame sensor have the same number of pixels yet because the the physical size of one sensor is larger than the other its pixels therefore are larger in order to yield the same number of pixels.

Dots in terms of 'Dots per Inch' (DPI) are a finite size related to the fixed length of the 'inch'. It is often used in terms of printing in which an image is applied using a matrix of colored dots. The greater the DPI the more perceived resolution. Resolution is a factor of viewing distance of the image. The closer the image is viewed the higher the desired need of DPI. An image on a roadside Billboard is a very low resolution image in terms of DPI where the dots are few yet huge for the viewing distance is quite far compared to the same image printed in a book or magazine.

Images viewed on electronic media such as here on the web are limited by other factors not affected by those in print.

edrobinsonjr Loc: Boise, Idaho

a6k,

You state "If I have an image with 3000 pixels across and print it at 300 DPI it will be 10" wide."

If I have an image with 3000 pixels wide and make a print 30 inches wide at 300 dpi it still only contains the representation of the 3000 pixels but is 30 inches across.

If I have an image 640 pixels wide and print it at 300 dpi will it be only 2.1 inches wide? Not necessarily.

I believe that dpi is a term generally used in printing and the pixel value is almost irrelevant. Please correct me if I am wrong.

Ed

CHG_CANON Loc: the Windy City

It's the exact opposite: pixels are the important value, 'dots' are irrelevant.

edrobinsonjr Loc: Boise, Idaho

Thanks for the correction. Senior moment. What was I thinking?

I should have said that the pixel value is less important to a printer filling your custom order. However, If the printer is given a low resolution image file - pixels - they may not be able to produce a quality print at any dpi value.

Ed

nikonbrain Loc: Crystal River Florida

Why do you care ? Unless you print . Some of you Guys spend more time figuring out how and why than simply doing ..printing and selling or enjoying the craft ....I print and sell so I can buy more toys or the next Camera or Lens .I don't worry why if it looks good I print it and the only time I worry about DPI is when I print It and that is always 300 DPI or 360 DPI the later when an Image is more high key so I lay down more ink per square inch ...My only other consideration is rendering intent based on the image weather Relative colorimetric , saturation , or perceptual ..each one leaves a different look to the final image ..In my preference choices in CC photoshop import to ACR is set to open all files @ 300 DPI..

Picture Taker Loc: Michigan Thumb

"nikonbrain" Great you think like me. I love taking pictures, if people like them, they buy them. If they are bad they won't. The way to judge your work is with the other guy's money.

fetzler Loc: North West PA

You obviously completely misunderstand effective focal length.

1. Focal length is a property of the lens and is independent of the sensor size.

2. In the past many folks were familiar with 35mm film cameras (Same size as FF sensor). For full frame sensors 50mm is considered to be a normal lens for this sensor size.

3. For an 8 x10" camera one needs a 300mm lens (approx.) to match the field of view of a 50 mm lens and for macro 4/3 the focal length is 25mm. FOV could be measured as an angle of view.

4. Depth of field depends on the magnification of the image on the sensor and the selected f number. Assuming that the f number is constant the depth of field for a head shot of a person will be less on 8 x10" film than it is when using micro 4/3. This is because the size (magnification) of the head on the micro 4/3 sensor is smaller when compared to the actual size of the head. Smaller magnification = more depth of field. The notion of effective focal length ignores any DOF considerations.

5. None of the above depends on the resolution of the film or sensor. The general results will be the same for a 1 mp, 10 MP or 100 MP image. Only the ability to resolve fine details is affected by the pixel density on the sensor. Of course, this assumes that the optical resolving power of the lens is not exceeded.

Ysarex Loc: St. Louis

That is not correct. Note in the illustration below two calculations for DOF are presented. Same camera, same magnification and same f/stop used for both calculations. According to you the DOF should be the same, but it isn't even close.

(Download)

Jack 13088 Loc: Central NY

What exactly was interesting about the observations?

Beenthere

Let's apply Dizzy Gillespie's rule of thumb for music, to digital photography. "If it LOOKS good, it IS good"

User ID

Expect to be corrected anyway ... even though quite clearly you are NOT wrong.

User ID

Whatever Dizzy Gilespie’s rule of thumb might have been I could never presume to know ... but I do know that you have actually paraphrased Duke Ellington.

Regardless, I could never disagree with Duke Ellington about music and likewise I happen to agree with your paraphrase about photography.

Beenthere

I believe they both used some version of the paraphrase.., but I could be wrong? Thank you for pointing that out, and agreeing with my basic thought.

John Hicks Loc: Sible Hedinham North Essex England

As long as you are content with the end result does it matter.

miteehigh Loc: Arizona

I have a question. How many a**holes can dance on the head of a pin?