Understanding Exposures not Understood

[Tee]

He apparently does videos for adoramatv and I watched some of them.

I think he has his own line of videos. Mark Wallace is the guy for Adorama who I like very much. Peterson's hair freaks me out and I can't watch him.

 

[ph0enix]

f/22 is a small aperture, not large. The f stop values are fractions.

 

[Ballistics]

You have to be careful with recommendations. Hundreds of people have recommended Understanding Exposure, and haven't actually read it themselves.

 

[JMorris271]

I have read Both Understanding Exposure and Petersons A Fieldguide to Digital Photography and found them both to be very vague with little to offer.
I am only speaking for myself here saying I did not feel my money was well spent on these books.
Opinions are always subjective. Bottom line is, know your source. I bought the books based on reviews on Amazon. My bad,

 

[RxForB3]

He does have his own series, but I assume it's sponsored by adoramatv. In any case they were in the adorama youtube lineup. I definitely like Mark Wallace better, though.

I think the book was worth my money in any case. I have to say I do dislike some of his pics. For instance, one video was about shooting night cityscapes. He recommended shooting at about 20 minutes after sunset and using a magenta filter. He compared his picture to the typical middle of the night picture and declared that if you were like most people you would like his better. I guess I'm not like most people, but then that's no surprise

 

[RxForB3]

So what is the exact correct terminology? I hear aperture referred to in so many ways. I realize that f/22 is the smaller opening, but even peterson referred to that as a large aperture. Technically since it's a reciprocal, f/22 would be a small value, so what SHOULD I call it.

 

[MTVision]

So what is the exact correct terminology? I hear aperture referred to in so many ways. I realize that f/22 is the smaller opening, but even peterson referred to that as a large aperture. Technically since it's a reciprocal, f/22 would be a small value, so what SHOULD I call it.

Where does he call it a large aperture? He says it gives you maximum depth of field. He also says that even when it's set to f/22 the image in the viewfinder is seen at a wide open aperture (f/2.8) until the shutter is pressed.

If he does call it a large aperture it's a typo because it is a small aperture which is proven when he calls f/2.8 a wide open (large) aperture.

 

[MTVision]

So what is the exact correct terminology? I hear aperture referred to in so many ways. I realize that f/22 is the smaller opening, but even peterson referred to that as a large aperture. Technically since it's a reciprocal, f/22 would be a small value, so what SHOULD I call it.

Wait - he does say it is the largest aperture number (f/16, f/22, f/32) but above where he says that he explains that the smallest aperture # is the widest open. So when you shift from a small aperture number to a larger one you are reducing the size of the opening and stopping down.

So f/22 is a large aperture NUMBER but a small opening. It is a small aperture...

 

[naptime]

well... thanks for this thread.


asia and i were going though some lessons the other day regarding the triangle and all three points..

in two of the lessons, this book was mentioned, and i thought i had seen in posted on here before as well.

i was going to buy it. but held off till i could get some opinions here..

i think i'll pass.


my worry was, and seems now to have been confirmed... that it's not the type of read i want.

i hate dry boring technical reads. or reads that don't thoroughly explain things in an easy to understand manner.

 

[MTVision]

Gotcha. I was already understanding most of that, but hadn't looked into the circle-of-confusion. Mainly, though, I wasn't understanding how exactly to implement the hyperfocal distance. It's kind of like exposing to something other than your subject (sky for instance). Focus away from the subject, lock it, then recompose. Thanks!

Exposing for something and recomposing are 2 different things. In Petersons books he mentions to expose for the sky - so you would just point the camera at the sky (you dont need to lock focus) and adjust your settings to get a decent exposure for the sky then you would focus on whatever it is you want to focus on.

Focus and recompose is when, for example, you use your center focal point to focus on your subject but you want to compose it differently. So you would half press the shutter button, reframe and then take the picture.

 

[MTVision]

well... thanks for this thread.

asia and i were going though some lessons the other day regarding the triangle and all three points..

in two of the lessons, this book was mentioned, and i thought i had seen in posted on here before as well.

i was going to buy it. but held off till i could get some opinions here..

i think i'll pass.

my worry was, and seems now to have been confirmed... that it's not the type of read i want.

i hate dry boring technical reads. or reads that don't thoroughly explain things in an easy to understand manner.

It honestly probably wouldn't have helped you anyways. It is very basic.....and covers things you probably already have a good grasp on it. But his book is easy to understand.....

 

[EchoingWhisper]

Certainly not arguing, so please correct wherever my misconception is. You say I'd have to get closer to fill the frame, but is that necessarily a bad thing? I realize that the closer you get the smaller the depth of field, but if I recall correctly from the dof calculator the hyperfocal distance for the 18mm on a canon would be about 2 feet. Shouldn't that be close enough to fill the frame appropriately even with a small subject such as the gecko?

Another thought/question. With the 100mm the hyperfocal distance is something like 30 feet at f/22. When using the lens for macro as opposed to say portraits, does the same focus distance apply? Hence the very shallow dof in macro?

No, not really, try to fill the frame with a gecko at 18mm 2 feet away.

 

[EchoingWhisper]

I do have an android smart phone. Do you have a specific dof calculator you recommend?

Any DOF calculator would do if you could set distance, focal length, and circle of confusion.

 

[EchoingWhisper]

Here's my opinion, Having been a Photographer for over 40 years I do understand the triangle But everyone raved about the book so I bought it. I thought it was a pamphlet and a vehicle for him to show pictures of his hit wife and brag about it. But everyone loves the book so what do I know.

Here's the thing with your DIF question, When framed equally, ( Equal magnification) Distance to subject and focal length cancel each other out and you will have the same DOF no matter the Focal Length/Distance to subject. So the only thing that will affect DOF is Aperture.

As far as him recommending f/22. Yes it will yield the greatest DOF but it will also introduce Diffraction within the lens and cause the image to be soft, especially on a cropped sensor camera.

As far as Hyperfocal distance goes, it's not the cure all to everything. It provides for the maximum DOF for a given Aperture. However it doesn't provide for the sharpest image, especially if you have a singular subject close to the camera. The sharpest point will be the point of focus and everything else is just wintin the field of acceptable focus.

The best of all worlds were to place your subject at the point of focus and that point being the hyperfocal distance also. So your subject would be the sharpest and then you would have a filed of focus from 1/2 the distance to your subject to infinity.

The reason that a wide angle lens will appear to have a deeeper DOF, has to do with perspective compression of bringing the background into closer view with a telephoto lens. You can then see that the backgrund is OOF even though the DOF is exactly the same it just to the eye doesn't appear that way.

You also have to take FOV into account with your Gecko shot. The shot's BG will look entirely different shot with a 18mm at 1' DTS than with a 180mm 10' DTS

The reason he suggests metering the blue sky is that in essence you are turning your Camare's Reflective meter into a Incident meter and metering the light that lights the scene (skylight) instead of what is reflected off your subject

Well written post.

 

[EchoingWhisper]

Gotcha. I was already understanding most of that, but hadn't looked into the circle-of-confusion. Mainly, though, I wasn't understanding how exactly to implement the hyperfocal distance. It's kind of like exposing to something other than your subject (sky for instance). Focus away from the subject, lock it, then recompose. Thanks!

Circle of confusion is determined by either your sensor's resolution (including the decrease of resolution due to the anti-aliasing filter) or the lens' resolution, whichever lower. Your lens resolution can be calculated by using the tests from DxOMark. They will show you the lp/mm accurately at resolution profile. lp/mm = Circle of confusion X 2. Why do you need to times two? Because it is lines PAIR. The circle of confusion of sensor with the AA filter is normally the pixel pitch times two.