What did you learn today?

[Eyelight]

Eyelight Plays with Depth of Field

Been too long away from creative photography and trying to refresh the old knowledge and learn about new equipment.

Basic idea is to plan a shot, take the shot and learn.

Plan was to make the toaster the subject and remove the bananas as subject by blurring them with the background.

First shot missed. I had focused on the toaster, and then adjusted focus back slightly. Too much!


Second shot was just fine.


I learned that at 105mm and f4.5 the DOF is only 2.78" which is barely enough to keep the front of the toaster in focus and that a very small movement of the focusing ring moves the focal point more than I thought it would.

I may add more posts as I fiddle with the new camera, lenses, etc. or anybody can add what they like. Writing this post, I thought of something else I need to explore.

Keep it simple. Plan the shot, take the shot and learn.

What did you learn today?

 

[Eyelight]

This is what I learned today.

Trying to come up with an easy way to explore the depth of field on the 55-200mm, so I set up the D3200 on a tripod aimed at the 10' mark on a tape measure. Using mode A and taking a shot at each aperture setting. Rotated and cropped each shot and added the aperture setting and DOF calculations below each image. If you enlarge the jpeg and scroll up and down, you can see the DOF on the tape at different settings. The blur is easiest to detect in the fraction marks along the edge of the tape.

The center appears to go soft around f/22-25, which I know everyone wants to call it diffraction, but it is probably just the normal loss due to the nature of economical glass.

I was using manual focus and as you can see missed it by 5”. After this I discovered the rangefinder, and hit three successive focus points, so learned something else today.

First shot is as seen by the camera. The rest are rotated a cropped for ease of viewing. What all this does for me is gives me a picture to save in my mind of how the DOF works on this lens at this distance and then think deeper DOF as the distance increases and shallower DOF as the distance decreases.

What did you learn today?

Just thought of the next thing to scope out.

 

[Eyelight]

Read something the other day that I'd never heard; the idea that depth of field would remain constant as focal length changes provided the subject occupies the same portion of the image.

So, set about using the tape measure to replicate the thought into reality.

The application would be that the aperture that provides enough DOF for the squirrel at 6 feet and 98mm will provide roughly the same DOF at 10 feet and 200mm and at any other focal length if the squirrel is framed the same size.

 

[hark]

I learned that at 105mm and f4.5 the DOF is only 2.78" which is barely enough to keep the front of the toaster in focus and that a very small movement of the focusing ring moves the focal point more than I thought it would.

The DOF might be 2.78" while shooting at 105mm using f/4.5 at whatever the exact distance was from your subject; however, the DOF will vary depending upon how close or far you are from your subject. Have you looked at a DOF online calculator?

Online Depth of Field Calculator

Keep up the learning process! It's great that you are taking the initiative to broaden your knowledge!

 

[Eyelight]

Have you looked at a DOF online calculator?

Yessir! I have used their calculator and the table generator. I also have Photo Caddie for my phone. DOF is kind of my pet project at the moment because I noticed I was missing the focus on that range of shot, which I have discovered was partly due to DOF and partly to my use of AF and/or manual focus.

 

[Eyelight]

It's been a photographically eventful day.

Started out working on a shortcut method of keeping track of DOF, but was sidetracked by focusing issues. The initial subject was a pair of concrete blocks.



Several sessions and 52 photos later I had determined I cannot hold a camera as steady as I used to. I was lucky to get a decent shot at 1/250, but was only consistent at 1/400 or faster at 200mm, which I suppose may not be so bad.

Anyway, the blocks were good subjects, they stood in the hot sun and didn't complain a word, but a photo needs some personality, so I decided to hire an assistant/model/stunt double/gopher (go for).



Meet Chupa, whose main purpose in life is to sit there and let me shoot at him whenever there is nothing else interesting to shoot.

Chupa did work on one project this afternoon, and that was helping me work on the DOF of the 55-200mm.


f/5.6 @ 1/800 and focused on Chupa's little head, but his little tail is a little fuzzy.


f/9 @ 1/320 and focused on Chupa's little head, little tail better, but not quite.


f/9 @ 1/400 and focused on Chupa's broad right shoulder to shift the DOF back just a little and bring the tail into slightly better focus.

Still working on the DOF shortcut idea, but it was a good day anyhow. Maybe tomorrow.

 

[Eyelight]

Re: Eyelight Plays with Depth of Field

This may be common knowledge, but something my film camera provided better info than the D3200. So, continuing to deepen my grasp of the way DOF works and perhaps come up with an easier way for my mind to see how DOF changes and determine what aperture to use to gain a desired effect.

Reading the Cambridge in Color website DOF article, it occurred to me that one could use the size of the subject to determine aperture and did not necessarily need to know the distance. This works because DOF remains fairly constant at different focal lengths provided the subject fills the same percentage of the view. So, a squirrel inside the DOF at 200mm will remain inside the DOF at 100mm or 75mm provided we move toward the squirrel and adjust the view to same we had at 200mm. There are exceptions. More at Understanding Depth of Field in Photography

To reinforce this in my mind, me and Chupa went out to play. Each of the three shots are at different focal lengths, but framed close to the same Chupa-size, keeping aperture at f/11 and the DOF appears to be pretty close in each. The application in my mind I can learn to relate subject size to an aperture (Chupa-size is an f/11) that keeps the subject inside the DOF easier than remembering distance + focal length + desired DOF = aperture (Chupa is 10' away at 200mm and I need 3" behind him, so the table says X).