"Understanding Exposure" - Question

[MikeandReneePlus5]

I am reading Byran Peterson's "Understanding Exposure" (3rd Edition)

Can anyone help me understand some comments on page 46?

What he is discussing is what he calls "storytelling shots" in which the foreground, middle ground and distance ground are all in focus in the shot. With respect to how to focus that shot:

He writes that "all single-focus lens had - and still do have - what is called a depth-of-field scale".

I have a Canon EF 50mm f/2.8 and I do not see what he is referring too.

Furthermore he writes in reference to zoom lens, which he says lack depth-of-field scale:

"What we do have are distance settings. The distance settings are similar to the depth-of-field scale in that they allow you to preset your depth of field before you take your shot.....you would first choose to set your aperture to f/22* and the align the distance above your distance-setting mark on the lens. Your focal length will determine which distance you choose"

I just don't get the bolded part. Where is this distance-setting mark and how do I align the distance above it????

I only have the fixed 50 and the 18-55mm kit lens for my Canon T2i.

*I know f/22 is a small hole and it seems many would say use f/16 to reduce contrast loss....not worried about that part and he discusses that in his book also as to why.

 

[seashoreCM]

Not all lenses, even high end lenses, have depth of field scales next to the focusing ring that look something like:

16 11 8 5.6 4 2.8 4 5.6 8 11 16

where the feet (or meters) span on the focusing ring between the two markings for the f/stop you choose represents the approximate range of distances in focus at the same time. But for a zoom lens, engraved marking of this kind can't be used because the correct spacing would vary depending on the amount of zoom.

The only way to set the depth of field is to set the aperture (f/stop). Look through the optical viewfinder and turn the aperture ring. Do you see a pair of unlabeled markings that get closer together or farther apart? Are there tiny focusing numbers in feet or meters visible in the viewfinder that can be slid past such a pair of markings as you turn the focusing ring? Or if there are no distance markings you can adjust the focusing ring to see where the closest important subjects become noticeably blurry and where the farthest important subjects become noticeably blurry. Set the focus halfway in between in terms of amount of ring rotation. The lens will stop down (and expand the depth of field hopefully covering both the closest and farthest subects) after you press the shutter button if you had chosen a smaller aperture.

When the lens is set to f/22 the depth of field is large enough that just about everything from 5 feet to infinity will be in reasonable focus if you set the focus to about 15 feet. However f/22 is practical only with cameras with fairly large sensors (at least about "APS" size or "half 35mm frame" size.) Small point and shoot cameras should not be set smaller than f/11 due to diffraction blurring involving very small lens openings.

 

[photo_chick]

On newer Canon lenses that have it, the distance scale is in a window. Sometimes it's by the end of the lens, sometimes it's by the mount.. it seems to be wherever they can get it into the design on Canon lenses. It's not on any of the entry level lenses. It's on most of the mid level and L series Canon lenses.

I think somewhere along the way they decided that people who used lower end lenses wouldn't need or want the information right there. You can use a distance measuring device like they do in golf, they work well for this. Or you can use your Canon's ADEP mode where it uses the auto focus system to choose two points then tells you what aperture you need to have those be the front and back of the depth of field and it can also give you distancce information. I find the golf laser thingy much easier for me, and I lifted mine free out of my husband's bag.

 

[MikeandReneePlus5]

Not all lenses, even high end lenses, have depth of field scales next to the focusing ring that look something like:

16 11 8 5.6 4 2.8 4 5.6 8 11 16

where the feet (or meters) span on the focusing ring between the two markings for the f/stop you choose represents the approximate range of distances in focus at the same time. But for a zoom lens, engraved marking of this kind can't be used because the correct spacing would vary depending on the amount of zoom.

The only way to set the depth of field is to set the aperture (f/stop). Look through the optical viewfinder and turn the aperture ring. Do you see a pair of unlabeled markings that get closer together or farther apart? Are there tiny focusing numbers in feet or meters visible in the viewfinder that can be slid past such a pair of markings as you turn the focusing ring? Or if there are no distance markings you can adjust the focusing ring to see where the closest important subjects become noticeably blurry and where the farthest important subjects become noticeably blurry. Set the focus halfway in between in terms of amount of ring rotation. The lens will stop down (and expand the depth of field hopefully covering both the closest and farthest subects) after you press the shutter button if you had chosen a smaller aperture.

When the lens is set to f/22 the depth of field is large enough that just about everything from 5 feet to infinity will be in reasonable focus if you set the focus to about 15 feet. However f/22 is practical only with cameras with fairly large sensors (at least about "APS" size or "half 35mm frame" size.) Small point and shoot cameras should not be set smaller than f/11 due to diffraction blurring involving very small lens openings.

ah ok...so my fixed 50mm just doens't have the scale. That's fine and answers that question!

And based on Potato Chick's comment I bet my kit lens doesn't have anything either but I don't have my camera so I can't check that until later (but I am pretty sure it doesn't...i would have noticed). So that explains that!

Thanks for the tips on manual focus ring....

I have another question...regarding meter reading....Peterson discusses one shot where he wanted 1/500 sec to freeze action. He took a meter reading off the distant horizon and blue sky and the camera told him f/4. Ok fine, I get that....but if I try and get a reading off a blue sky my camera gets wonky and won't respond...nothing to to focus on! what am I doing wrong?

 

[Shutterbug]

I have another question...regarding meter reading....Peterson discusses one shot where he wanted 1/500 sec to freeze action. He took a meter reading off the distant horizon and blue sky and the camera told him f/4. Ok fine, I get that....but if I try and get a reading off a blue sky my camera gets wonky and won't respond...nothing to to focus on! what am I doing wrong?

Put your lens into manual focus and then take your meter reading. In manual focus the camera wont care about the focus and will just meter the lighting of the scene.
Also when you do that try different metering methods ie spot metering, center weighted and evaluative. Each one will yield diff effect.

 

[MikeandReneePlus5]

Put your lens into manual focus and then take your meter reading.

A-HA!

*shakes head in shame for not figuring that out myself*

 

[bob100]

I have another question...regarding meter reading....Peterson discusses one shot where he wanted 1/500 sec to freeze action. He took a meter reading off the distant horizon and blue sky and the camera told him f/4. Ok fine, I get that....but if I try and get a reading off a blue sky my camera gets wonky and won't respond...nothing to to focus on! what am I doing wrong?

nothing wrong! the exposure meter and focusing are two different things, The indicator on the LCD (or viewfinder) will still give you the correct aperture depending on shutter speed and ISO even though it cannot focus on a blue sky. If you want to actually take a picture of a blue sky then it might make sense to use manual focusing

 

[pjacobi]

The Depth-of-Field scale is different on each of the 3 Canon 50mm lenses:

50mm f/1.8 = no scale
50mm f/1.4 = 22 | 22
50mm f/1.2 = 16 11 8|8 11 16

More important than the scale, is the Depth-of-Field Preview button. The viewfinder will darken but you will be able to see exactly which areas of the image will be in focus.

On any modern SLR/dSLR, selecting the f/stop does not change the iris! Only when the shutter is pressed does the iris move to the selected position momentarily for the exposure, then returns to the wide open position. The Depth-of-Field Preview button to forces the iris to close to the selected f/stop so the results of depth of field can be seen in the viewfinder.


-Paul

 

[GrumpyGoat]

The depth of field scale on lenses pretty much went away with the advent of autofocus lenses.

Here's what one looks like on an old manual focus 135mm lens manufactured some time during the 1960's or 70's...

It's the scale between the focusing ring and the aperture setting ring...

 

[MikeandReneePlus5]

nothing wrong! the exposure meter and focusing are two different things, The indicator on the LCD (or viewfinder) will still give you the correct aperture depending on shutter speed and ISO even though it cannot focus on a blue sky. If you want to actually take a picture of a blue sky then it might make sense to use manual focusing

Did not realize that, but sure...it makes sense. Light is light, and focus and focus. As Homer would say....D'OH! Many thanks!

(can't wait to get home and start playing)

The depth of field scale on lenses pretty much went away with the advent of autofocus lenses.

Here's what one looks like on an old manual focus 135mm lens manufactured some time during the 1960's or 70's...

It's the scale between the focusing ring and the aperture setting ring...

Awesome pic to bring it fully home, thanks.

On any modern SLR/dSLR, selecting the f/stop does not change the iris! Only when the shutter is pressed does the iris move to the selected position momentarily for the exposure, then returns to the wide open position. The Depth-of-Field Preview button to forces the iris to close to the selected f/stop so the results of depth of field can be seen in the viewfinder.

-Paul

Now there was another part of the book where I was a little fuzzy...to DOF preview part...had to read Peterson's description several times and vowed to come back to that (it was past 11 pm and I was tired and my head was spinning). You've explained it very well and now I understand!!!

This board is great.

 

[Altair]

Using GrumpyGoat's lens photo: To use the depth of field scale to get the most DOF you would do this. If are shooting at f/22, move the infinity mark to the 22 on the right of the scale. Then look to the left side of the scale for the 22 and look down to what foot mark that lines up with, in this case it would be around 20 feet. So everything from 20 feet to infinity would be in focus. This is how to get the most DOF possible.
You can get the same results with a lens without the scale by just moving the focus of your lens off infinity before taking the shot. You just won't know exactly how far to move for sure.
This is a secret only old photographers know.