Focus distance is the distance from the camera to the subject. I assumed it was to the image plan but thinking more I don't know that for sure. It could be that it is measured to the some part of the lens. I have sent the Simple DOF App supplier that question. Thank you for asking.

No, DOF is not 5'.
Per the app, with a FF sensor, with 50mm lens @ f5.6, and the subject 5' away, DOF is: 1 foot + 0.13 inches
That is 5.46" starting at 5' moving toward the camera, and 6.67" starting at 5' moving away from the camera.

Seems like no one noticed in my original post I said:
FYI - When I am shooting, i don't do math, I just look thru the viewfinder and I use DoF preview to assess the DoF.

I started all this wondering if there was something equivalent to the crop factor for focal length, but instead for DOF. So for a M43 lens the crop factor is ~2. A 50 mm M43 lens has (approximately) the same field of view as a 100mm FF lens. But what is the equivalent focal length for the same DOF? Empirically it looks to be approximately the square root of the crop factor; 71mm on the M43 lens to get the same DOF as 100mm on the FF lens. I was wondering if that was a coincidence or is there math behind it? So far, no one has answered that.

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Yep it has been improving but I am still glad they still have the old versions of content aware fill. Sometimes one of them still works better.

yes.


F-stop = focal length / aperture_diameter

It’s a normalized value. F5.6 on a 100mm lens at 1/500 sec will give you the same exposure as F5.6 on a 50mm lens at 1/500 sec.

[quote=cyan]HA!! I can tell you it is far from perfect.

A while back I watched a video a guy removed some wires using AI. He had a pretty clean skyline with wires in it. I had an image with wires in the sky and there were some trees on the edge of the frame and the wires entered the trees. I tried his step by step instruction on my image. The result was horrible. it placed pieces of wires and trees all over the sky and sky in the trees. A complete mess -> Into the TRASH. I stopped worrying about AI taking over at that point.

Eric a.k.a. ebrunner posted a beautiful flower pic yesterday https://www.uglyhedgehog.com/t-805823-1.html and that inspired me to take some pics of my girlfriend's Freesia flowers. Thank you Eric.

Mine is not BW but I think that is ok for this shot. I submit the attached for your consideration.

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Very good. Guide = Planning. And the guide didn't take the photo. ;)

This is exactly correct!! AI can help do the mundane things and free us up for the more creative & enjoyable things.

Of course AI might resent that, then we get the Skynet problem when the machines decide to eliminate the humans.

Shooting with 2 formats, Full Frame (FF) and Micro43 (M43) it's OBVIOUS Depth of Fields (DOF) are not equal for the same focal length.

FYI - When I am shooting, i don't do math, I just look thru the viewfinder and I use DoF preview to assess the DOF.

But I was curious if there was a relation, something like the crop factor. But for DoF instead of for field of view. Various u-tube tutorials describe it differently. Some seem to contradict one another. One person said divide by the crop factor but that seems wrong. One of the u-tube videos said with the same framing you get the same field of view. But that's difficult to access because the aspect ratios are different.

So I used my iPhone Application, Simple DoF and did a few comparisons.
Summary below, the columns are:

F-stop focal length focus distance DOF_calculation in feet and inches.
(Apologies to the metric people)

Full Frame
F5.6 50mm 5' 1' 0.13"

M43
F5.6 50mm 5' 0' 6.02"
F5.6 35mm 5' 1' 0.51"
F5.6 25mm 5' 2' 1.48"

So it looks like 35mm gives a pretty close DOF to FF. That's interesting because 35mm is
approximately what you get dividing by the square root of the crop factor.

Let's try it with F4
FF
F4 50mm 5' 0' 8.53"
F8 50mm 5' 1' 5.33"
F16 50mm 5' 3' 0.93"

M43
F4 35mm 5' 0' 8.80"
F8 35mm 5' 1' 5.88"
F16 35mm 5' 3' 2.26"

Again M43 @ 35mm focal length is close to FF @ 50mm focal length.

Let's try it with FF@100mm and M43@71mm

5' Focal distance
FF M43
100mm 71mm
F4 2.05" 2.08"
F8 4.11" 4.16"
F16 8.24" 8.34"

15' Focal Distance
FF M43
100mm 71mm
F4 1' 7.37" 1' 7.34"
F8 3' 3.09" 3' 3.02"
F16 6' 9.01" 6' 8.36"

There is probably some mathematical explanation for this, maybe someone here with optics knowledge can explain it. Or is it just a coincidence?

Luck, planning, skill are three elements that go into any shoot. The % of each can vary greatly.

I agree with that. Well said.

I don't know if your referring to my comment above but that's ok if you were. However I don't believe I'm on shaky ground because I said "in its current state". Yes it is being used in many other ways besides photography, video and movie production for instance, and it can be used to re-create likenesses of actors. That was a big issue in the recent actors guild strike. It's also being used in tech and finance.

Like any other tool, it will be used for good and for nefarious purposes. It's not AI but the values of the user that will determine the end use (good or evil).

I like backlighting and I love that shot! Very Nice work!

That software would have to be itself AI.

I think the fear over AI is much ado about nothing. In its current state, it’s an extension of the processing tools we used to retouch images.

It has a potential to do more than that and as it valves, we’ll see how that fits in. I don’t see it replacing humans, but rather extending what they can do, like a tractor helps a farmer tend a bigger field.

most of all have fun. - Joe NcNally

I have noticed your absence and I am glad you were ok. Sometimes we need a break. Welcome back! Re the flower, that is very nice work! I like it!!

I think we are in violent agreement! lol.

Regarding movies, a big issue in the most recent strike was how production companies and producers use AI to recreate images of actors/actresses and recreate their voices. It’s reality now not in the future.