DOF - m43 compared to APS-C examples?

bur437 said:

Bilgy_no1 said:

These are great shots, especially with manual focus. But not that using this lens on a m4/3 camera, you'd get exactly the same DOF, only with a smaller crop of these pictures. They would be cropped most notably on the longer side of the image, in this portrait mode the height would be reduced, the width not so much.

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So by this reasoning if i shot the CV25 (.95) but used at f1.2 on a m43 camera and i shot the cv35 (1.2) and used at f1.2 on APSC i would get almost identical shots with equivalent DOF? I'm not sure this is true ... time to investigate.

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No, not quite. In that case, you're using lenses with different focal lengths. The 35mm will give more shallow DOF than the 25mm.

The lens determines the amount of DOF, together with the focus distance. What I said above is true for:

• The same lens (focal length and aperture)
• The same focus distance

But the Angle of View would be smaller on the m4/3 system; it would capture a smaller crop from the image circle than the APS-C sensor.

If you want to equal the Angle of View, and the DOF with a m4/3 system as with an APS-C system, you would need either to:

• use a shorter focal length lens (so 25mm instead of 35mm like you say above), and use a brighter aperture (so not both lenses at f/1.2 like you say above, but one at f/1.2, the other at f/0.95), or
• use the same focal length lens, but increase the distance to the subject and use a brighter aperture.

Here's an overview of different sensor sizes. If you would place the APS-C 1.5x crop factor on the edges of your posted shots, the green line shows the m4/3 crop. One step back would give practically the same image, and that would hardly impact the DOF:



As has been said before, the difference between APS-C and m4/3 is not so big for the issues of DOF.

(Note that it makes a difference if you want to make things equal for the horizontal resolution, or for the vertical resolution. That's why the GH2 sensor is so smart: it uses a wider resolution for 3:2 and 16:9 ratios, so it comes very close to Canon APS-C (1.6x crop) for 16:9 shooting videos.)
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http://www.flickr.com/photos/bilgy_no1

Bilgy_no1 said:

bur437 said:

Bilgy_no1 said:

These are great shots, especially with manual focus. But not that using this lens on a m4/3 camera, you'd get exactly the same DOF, only with a smaller crop of these pictures. They would be cropped most notably on the longer side of the image, in this portrait mode the height would be reduced, the width not so much.

Click to expand...

So by this reasoning if i shot the CV25 (.95) but used at f1.2 on a m43 camera and i shot the cv35 (1.2) and used at f1.2 on APSC i would get almost identical shots with equivalent DOF? I'm not sure this is true ... time to investigate.

Click to expand...

No, not quite. In that case, you're using lenses with different focal lengths. The 35mm will give more shallow DOF than the 25mm.

Click to expand...

But that was my point the equivalent focal length of 25mm on m43 and 35mm on APSC would be very similar but the APSC would have shollower depth of field, wouldnt it?

Bilgy_no1 said:

The lens determines the amount of DOF, together with the focus distance. What I said above is true for:

• The same lens (focal length and aperture)
• The same focus distance

Click to expand...

Yes I agree that focus distance is important, maybe even more important than aperture in some cases.

Bilgy_no1 said:

But the Angle of View would be smaller on the m4/3 system; it would capture a smaller crop from the image circle than the APS-C sensor.

If you want to equal the Angle of View, and the DOF with a m4/3 system as with an APS-C system, you would need either to:

• use a shorter focal length lens (so 25mm instead of 35mm like you say above), and use a brighter aperture (so not both lenses at f/1.2 like you say above, but one at f/1.2, the other at f/0.95), or
• use the same focal length lens, but increase the distance to the subject and use a brighter aperture.

Click to expand...

bur437 said:

Bilgy_no1 said:

bur437 said:

Bilgy_no1 said:

These are great shots, especially with manual focus. But not that using this lens on a m4/3 camera, you'd get exactly the same DOF, only with a smaller crop of these pictures. They would be cropped most notably on the longer side of the image, in this portrait mode the height would be reduced, the width not so much.

Click to expand...

So by this reasoning if i shot the CV25 (.95) but used at f1.2 on a m43 camera and i shot the cv35 (1.2) and used at f1.2 on APSC i would get almost identical shots with equivalent DOF? I'm not sure this is true ... time to investigate.

Click to expand...

No, not quite. In that case, you're using lenses with different focal lengths. The 35mm will give more shallow DOF than the 25mm.

Click to expand...

But that was my point the equivalent focal length of 25mm on m43 and 35mm on APSC would be very similar but the APSC would have shollower depth of field, wouldnt it?

Click to expand...

Yes, that's true. But the difference would be small. It would be all but negated by the f/0.95 vs f/1.2 aperture difference between the lenses.

OP sighs... still no direct comparisons... :-(

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http://www.flickr.com/photos/bilgy_no1

Bilgy_no1 said:

OP sighs... still no direct comparisons... :-(

Click to expand...

I strongly suspect that there are no direct comparisons posted here because we don't go to the trouble and expense of shooting m43 and APS both when there's really not much difference. There seems to be a consensus that m43 and FF is a good choice for dual format users.

Bilgy_no1 said:

Gravi said:

Hi,

I can imagine that you want to photograph with creative DoF possibilities. But going from m43 to APS-C won't do that much difference. It is about 2/3 of a stop. The difference between APS-C and fullframe is about 1 1/3 stop. And the difference between fullframe and m43 is 2 stops.

I own both a Canon APS-C camera (Canon 7D) and a GF1, and have shot with fullframe. If you want maximum DoF contol, go fullframe, and be prepared to spend a lot of money.

APS-C has its good sides, in my eyes mainly a huge lens selection, and esp for macro and tele photography APS-C is the way to go, unless you have unlimited funds and a strong back (then FF could be considered).

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I'm curious about this statement. Theoretically, the 2x crop of m4/3 would give an advantage for tele photography? And the same would go for macro, because it would be (a tad) easier to get enough (yes enough ) DOF than with APS-C?

Am I overlooking something?
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http://www.flickr.com/photos/bilgy_no1

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anything. For certain types of photogrpahy (portrature, telephoto, macro) FF DOF, especially wide open is way too narrow. 4/3 (and thus u 4/3) is really the ideal format for those types of photography. Kodak and Oly thought all this through when they selected the 4/3 format. Remember, Kodak invented APS and abandoned it for 4/3 format. You can throw rocks at Kodak but when it comes to the basics of photography, nobody knows more.

As said above, there is not much difference in DOF between 4/3 and APS-c. To the extent there is, it can easily be matched with very minor changes in focal lenght.

Tedolph

Do you remember the magazine?

You are ignoring the effect of image magnification.

With the same lens, and the same focus distance, the smaller crop results in a smaller image - unless you magnify it to the same print size - which reduces the depth of field. (Comparisons of DOF are normally done at the same viewing size/distance)

Your argument also ignores the factor most people are interested in - for a different sensor size, but achieving the same image (Same subject distance, and same angle of view), you need a wider lens on the smaller sensor - which then more than compensates for the extra magnification and results in deeper DOF - hence the "approx 2/3 stop" factor.

--
Tony Collins

Tony Collins said:

You are ignoring the effect of image magnification.

With the same lens, and the same focus distance, the smaller crop results in a smaller image - unless you magnify it to the same print size - which reduces the depth of field. (Comparisons of DOF are normally done at the same viewing size/distance)

Click to expand...

Yes, there's a 'circle of confusion' issue, that everyone has ignored in this discussion so far. It does indeed give a smaller DOF on m4/3 than on APS-C. But that effect too will be very small.

Member said:

Your argument also ignores the factor most people are interested in - for a different sensor size, but achieving the same image (Same subject distance, and same angle of view), you need a wider lens on the smaller sensor - which then more than compensates for the extra magnification and results in deeper DOF - hence the "approx 2/3 stop" factor.

Click to expand...

I don't think it did: use a shorter focal length and brighter aperture, or move back and use a brighter aperture.

Note that I responded to a posting where someone showed shallow DOF on a NEX with the CV 50mm f/1.1, where the same lens on a m4/3 would have yielded almost identical photos in terms of DOF with the same framing, or exactly identical DOF at the same subject distance but with a slight crop.

Those shots, by the way, were excellent photography. I think the poster would have achieved excellent results with a m4/3 camera as well.
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http://www.flickr.com/photos/bilgy_no1

Not exactly.

A 50mm f1.4 produces the same DOF regardless sensor -

BUT that assumes you're going to stand in the same place. The issue with this logic is you're not going to stand in the same place. With the crop sensor, you'll stand further away from the subject and compose accordingly. That will increase the DOF.

If you're going to shoot with different focal lengths so that you can stay in the same spot and get composition mostly the same, then the larger sensor has a shallower DOF at equal fstops.

Here's an easy way to envision it. lets say you use the 35 on the m43. You're standing in the same spot. Your DOF is shallower than the 25 and you're zoomed in more. Now take several pictures and stitch it like a panorama - effectively similar to using a larger sensor. Your DOF doesn't change because you've stitched.

bur437 said:

Bilgy_no1 said:

These are great shots, especially with manual focus. But not that using this lens on a m4/3 camera, you'd get exactly the same DOF, only with a smaller crop of these pictures. They would be cropped most notably on the longer side of the image, in this portrait mode the height would be reduced, the width not so much.

Click to expand...

So by this reasoning if i shot the CV25 (.95) but used at f1.2 on a m43 camera and i shot the cv35 (1.2) and used at f1.2 on APSC i would get almost identical shots with equivalent DOF? I'm not sure this is true ... time to investigate.

Click to expand...