I can't get the hang of this Depth of Field lark!

[Ed Bray]

What can I say? It's beyond me! :banghead:

I thought that the more you opened up the aperture the less Depth of Field you got, but I took three different images all at the same exposure settings (1/10 sec @ f3.5, exif intact) all with the same lens from the same distance and the Depth of Field is different in all of them

Focus in all images was on the third Uniross battery from the right.

Beats me!

 

[12sndsgood]

You took all three photos at f/3.5?

 

[Ed Bray]

You took all three photos at f/3.5?

Yes. Same lens, aperture, shutter speed, and subject to lens distance.

 

[Railphotog]

You took all three photos at f/3.5?

Sure doesn't look like it.

 

[Overread15 3]

Distance - aperture - recording format size (ie sensor/film size - which affects circle of confusion)

Those should be the primary properties that affect the depth of field in a photo. For the 3 you've posted you must be changing something shot to shot in order to be getting the effect that you are. Either you're EXIF is reporting wrongly or your doing something else.

That or you're using a tilt shift lens to mess with the plane of focus and trick us
Or you're focus stacking

edit - based on the last shot my money is on tilt shift !

 

[KenC]

The camera angle changed. in the last one, the camera was closer to perpendicular to the row of batteries. If you compare the relative sizes of the batteries on the ends you will see this. You had the same DOF, but in the last the distance between the closest and furthest batteries was less, so the DOF covered it.

 

[Ed Bray]

Distance - aperture - recording format size (ie sensor/film size - which affects circle of confusion)

Those should be the primary properties that affect the depth of field in a photo. For the 3 you've posted you must be changing something shot to shot in order to be getting the effect that you are. Either you're EXIF is reporting wrongly or your doing something else.

That or you're using a tilt shift lens to mess with the plane of focus and trick us
Or you're focus stacking

edit - based on the last shot my money is on tilt shift !

Well my little April Fool didn't last for too long. I was hoping for a few more suggestions before it was rumbled!

 

[pgriz]

Ummmm... It's April 1, so....

Clever trick, tho!

 

[molested_cow]

I say you stacked the photo and saved it to the first photo, therefore the original exif data.

2 hours left on April Fools here.

edit: ok never mind.

 

[analog.universe]

24mm f/3.5 is too strong a clue

jealous of that glass...

 

[pgriz]

You took all three photos at f/3.5?

Gertrude, the OP was making an April Fools joke. He has a tilt-shift lens that changes the plane of focus, allowing him to get the line of batteries in focus (because the tilt matches the line of the batteries). The depth-of-field at f/3.5 is still thin, but now he aligned it with the plane of the subjects. For those who don't have the lens, it's an impossibility, for those who do, it's welcome magic.

 

[Ed Bray]

You took all three photos at f/3.5?

Yes, all three images were taken with the same aperture (wide open at f3.5), same shutter speed (1/10 sec), same ISO (800), same lens (24mm f3.5 TSE MkII) on the same camera (Canon 1DMk3) and from the same subject distance. All three shots were taken within minutes of each other.

How was it done:

The first image was a straight shot of a row of batteries at an angle to the camera's position with a 24mm tilt/shift lens set up for left/right tilt (commonly known as swing). The lens tilt position was set at neutral and the lens was focused on the 3rd battery from the right.

The second image was taken from a similar position but the lens was tilted as far as possible away from the line of the batteries (swung to the left) this made the plane of focus almost at right angles to the line of the batteries and thus when the lens was focused again on the 3rd battery from the right the minimal DOF at f3.5 ensured it did not even encapsulate the batteries on either side of the battery that was in focus.

The third image was again taken from a similar position but this time the lens was tilted to extend the plane of focus along the line of the batteries (swung to the right) and in this position the minimal DOF was sufficient to cover the front of the line of batteries (giving the impression of a great DOF) but if you look carefully you can actually see that the limited DOF at f3.5 has not covered the rear edge of the right most battery, this should have helped give the game away.

If these batteries were being shot as a product shot then the technique used in image 3 would normally be used but using a smaller aperture to ensure that the DOF was sufficient to fully cover the front battery too.

Hope this helps.

Took me so long to write this pgriz had already explained the situation. Unfortunately I no longer have the Canon kit with which I took these images a couple of years ago, but I do now have a pair of Fuji GX680s (a MkII and a MkIII) and these cameras allow a greater range of movements (than the Canon TSE lenses) with all of the lenses in the GX and GX-M range.

 

[pgriz]

Ed, I think we both responded to a "bot" posting. The burst of comments and their content do not imply a dedicated photography enthusiast.

Aside from that, you are making me lust for a swing-tilt lens. I've seen the magic it does in architectural and nature photography, and it allows effects that you just can't get any other way.