Digital Photography Forum
(This post is a continuation of another discussion started elsewhere. To read the original post, click here.)
As we saw last time, the aperture of the camera, which is indicated by the f-numbers, is one of the three controls which manipulates how light or dark the final image will appear.
This is not, however, the only thing that the aperture controls.
As the aperture, which is like the iris of an eye, opens and closes it also changes one other crucial aspect of the image, namely how much of the scene will appear in focus.
Let me demonstrate: in this first image, the aperture is at the smallest size which my lens is capable of, namely f29. (As we have seen this indicates that the diameter of the aperture is a twenty-ninth of the size of the focal length of the lens.)
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†In this image, the words "Multiple-Sector Meters" are in sharp focus, the words "The enormous disadvantage" are acceptably sharp, but the words "Centre-weighted meters" are out of focus and barely legible.
For the second image, I have increased the size of the aperture, which is now represented by the smaller number f10.
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†As we have seen in our previous exercise, to keep the brightness of the image the same, I had decrease the shutter speed to ensure that the same amount of light reaches the sensor.
As the size of the aperture increases, an interesting change occurs. The distance in front of and behind the area of sharp focus that remains sharp decreases.
While the words "Multiple-Sector Meters" are still razor sharp, the words "The enormous disadvantage" are no longer in focus and are barely legible, while the words "Centre-weighted meters" have drifted completely out of focus and are no longer legible at all.
In our final image in this set, I have increased the size of the aperture further to f4.5. (I obviously decreased the shutter speed further to compensate for the increased amount of lens that will flow through the lens.)
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†
?Ǭ¨?Ǭ®?Ǭ¨?ǬÆ?Ǭ¨?Ǭ®?Ǭ¨?ɂĆ?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢ÀÜ?°?¢ÀÜ‚Äö??¢ÀÜ?°?ɬ´?¢‚Ǩ?°?É‚Äû?ɬ??¢ÀÜ?°?É‚Äò?¢‚Ǩ?°?É‚Äû?¢‚Ǩ¬†In this image, the words "Multiple-Sector Meters" still remain sharp, but virtually everything else is out of focus.
There are other factors that will affect the size of the area that will remain in focus, such as the focal length of the lens and the distance for which the lens is focused, but these are discussed further in our section on Aperture and Depth of Field in the Basic Photography section of the magazine.
Thank you Ed. I totally see
Thank you Ed. I totally see the difference. That last photo just amazes me. It's something I'd like to try to recreat when i have some down time.¬¨¬®¬¨¬Æ¬¨¬®¬¨?Ü‚Äö?Ñ????ë?????´‚Äö?Ñ????ë‚Äö?тĆ Would my camera be able to do that?
I'm also going to read the link you provided.
A true photograph need not be explained, nor can it be contained in words.
~ Ansel Adams
Vicki
For sure.
Your camera definitely will be able to do it.
All you need to do is to adjust the aperture, as you did in the previous exercise, and you will get these results.
If you have any problems, let me know.
By the way, I liked your hundredth entry, now just don't go quiet on us :)