APS sensors vs. m4/3?

[Naveed Akhtar]

another visual help understanding the point: Dof related to focal length not sensor size:

The largest box represents full frame. The others represent 1.3 (Canon), 1.5 (Nikon) and 1.6 (Canon).

Here this tells, FOV is different but Dof is not, provided the same focal length and focal distance!

 

[flash]

Here is a result of quick search on google:
Andre's Blog • DOF: 35mm vs. APS-C



The reason why you getting different results is because when you select 50mm on 4/3 .. it is NOT .. let me repeat again IT IS NOT 50mm but 25mm focal length.

Regards!

I did that too. The results are still not the same.

Gordon

 

[flash]

Hey, what would I know. I've only been shooting professionally and teaching this stuff for nearly 20 years.....

The calculation for DOF is based on the print size and the viewing distances (standardised at 7x5 inch print at a 12" viewing distance) and the amount of enlargement required to create a CoC on the PRINT (hence the reason that the measured CoC is different for different sized sensors). In your visual above, each box is at a different size. Take each of the boxes make them the same size, put them next to each other and then see if you still feel the same way. In fact if you make the same print in different sizes the apparent DOF changes. To compare DOF you need to have images displayed at the same size. Your visual does nothing but demonstrate the relative size of different sensors. It is NOT a representation of DOF based on different sensor sizes.

Search the web man, leave those calculators behind .. dont send me the link of another calculator as a proof please!

because we all know that everything you read on the web just must be true..... Would you prefer I give you references to several dozen texts on the subject?

Gordon

 

[Naveed Akhtar]

Hey, what would I know. I've only been shooting professionally and teaching this stuff for nearly 20 years.....

I am not surprised, you sound knowledgable. But number of years (could be 100) doesnt count here at all!

The image I posted you is to teach the concept in simple way. Of course its one image, maybe shot from a mid format camera, who knows. If you can see it and understand the point, that was the whole purpose. I saw it on another forum earlier, and people seem to agree on the point, after seeing it!

because we all know that everything you read on the web just must be true..... Would you prefer I give you references to several dozen texts on the subject?

No, just read the one that make sense to you. That is why I asked you to do a simple experiment yourself and share your result with us. Just make sure the focal length and the distance should remain same. The first link I send to you did the same thing. You dont need to send dozen links, if you find only ONE that have same setup as I asked THREE times before, just post the link. Just make sure its same lens (better be a prime), fixed at same distance (better on tripod), use same apperture (better in whole number) and tested on different sensor size camera bodies.

The key to focus on the point is that "the image your lens is drawing on a plan is same from a particular lens at that focal length, apperture and distance to point of focus, now put any size of film, paper, sensor or anything, it will not change the image at all, no .. nothing at all ... it will only just crop it with different ratios according, and simply no other impact, WHATSOEVER"!
Basic Physics light and reflection!

 

[pdh]

I think the point, Naveed, that Gordon is making is not about the length of time, but the depth of knowledge he has.

He explains the situation accurately and clearly, for which I'm grateful. This is an area which seems to cause a very large "circle of confusion" for people who don;t understand the physics correctly.


I'm also wondering whether this is getting quite off topic for the thread?

 

[Naveed Akhtar]

I think the point, Naveed, that Gordon is making is not about the length of time, but the depth of knowledge he has.

He explains the situation accurately and clearly, for which I'm grateful. This is an area which seems to cause a very large "circle of confusion" for people who don;t understand the physics correctly.

I have no doubt on his depth of knowledge, there is a point which should not be that confusing, but surprisingly many experienced and very professional seems confused. I don't want to keep everyone on this point but I think if Gorden wants to prove something here, we should give him this chance.

I'm also wondering whether this is getting quite off topic for the thread?

The title of the thread is APS vs m4/3 sensor and we are talking exactly about sensor sizes and their impact on Dof. As this is one of the biggest reason why many chose FF. But, I am still happy to leave this discussion right there. However, if someone want me to respond on something, feel free to drop me an email or create a new thread and am happy to respond there.

 

[flash]

So here we go. Two cameras. Different sensor sizes. Shooting exactly the same scene from the same position on a fixed tripod, using the exact same lens. Both shot using a Leica 90mm Summarit lens set at 2.8. Shooting distance was 1 meter at an angle of approximately 45 degrees. Photos shot in RAW opened in Lightroom and exported at 900 pixels. There is no cropping. Focus point is on the middle "0" in "500".

Leica M9, 90mm Summarit @2.8.

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Panasonic GH2 with aspect ratio set to 3:2, Leica Summarit 90mm and CV m to 4/3 adaptor @ 2.8

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Doesn't matter which way you cut it DOF is not the same in these two images.

And just for fun. Here is a shot from the Panasonic/Leica 45mm macro lens @ 2.8 on the GH2.

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Again. Different DOF.

It's late. I'm off to bed.

Gordon

 

[Crsnydertx]

another visual help understanding the point: Dof related to focal length not sensor size:
View attachment 2623

The largest box represents full frame. The others represent 1.3 (Canon), 1.5 (Nikon) and 1.6 (Canon).

Here this tells, FOV is different but Dof is not, provided the same focal length and focal distance!

Named, the same diagram is useful in explaining that crop sensors don't "magnify" an image vs. full-frame for a given lens.

 

[Amin]

another visual help understanding the point: Dof related to focal length not sensor size:
View attachment 2623

The largest box represents full frame. The others represent 1.3 (Canon), 1.5 (Nikon) and 1.6 (Canon).

Here this tells, FOV is different but Dof is not, provided the same focal length and focal distance!

What this overlooks is that in order to get the same final print size, the crop captures have to be blown up more, which makes any blur look more blurred. Gordon's example above demonstrates this point.

 

[Amin]

Named, the same diagram is useful in explaining that crop sensors don't "magnify" an image vs. full-frame for a given lens.

True, but crop sensors tend to have higher pixel density, so given a fixed subject distance and focal length, and provided a sharp enough lens, a crop sensor can often provide greater effective "reach".

 

[Crsnydertx]

True, but crop sensors tend to have higher pixel density, so given a fixed subject distance and focal length, and provided a sharp enough lens, a crop sensor can often provide greater effective "reach".

Fair enough - "reach" is a better word than "magnification" for the phenomenon!

Of course there's a downside to higher pixel density...noise. But that's another subject.

 

[Amin]

Fair enough - "reach" is a better word than "magnification" for the phenomenon!

There is no additional magnification at the focal plane, but the "reach" can translate into more magnification at the print level.

Of course there's a downside to higher pixel density...noise. But that's another subject.

Definitely another subject and a highly controversial one at that.

 

[Luke]

the ease of shooting a shallower DOF is for me the biggest draw for APS-C, but not enough for me to buy into the DSLR world.

 

[Luckypenguin]

This is why I think the theory that (to give one example), a 25mm f.14 m4/3 is the same as a 50mm f2.8 full-frame in terms of angle-of-view and depth-of-field is an over-simplification. That is, the depth-of-field bit is an over-simplification, not the angle-of-view.

 

[Brian]

Numerically, the DOF of a 50mm lens at F2.8 on the M9 is the same as the DOF of a 25mm lens at F1.4 on the EP2. If photographing the same scene from the same position, printing both to the same size, and viewing those prints from the same location- they should look about the same. The EP2 has higher pixel density than the M9, but has an AA filter. The printer used to make the viewable prints will most likely nullify differences in the sensors.

Not interested enough to put the 25/1.4 on the EP2 and 50/1.4 on the M9 to test this. Scene content has more to do with real DOF than the scale on a lens.

 

[woof]

I continually pump the shutter in SAF mode as I follow the action.

The new OM-D claims to have the fastest AF of any system camera, so I think the slow AF point is out-of -date and can be forgotten as the last gasp of the APS crowd to discredit the new format.

I'll try it this way... thanks.

 

[Naveed Akhtar]

So here we go. Two cameras. Different sensor sizes. Shooting exactly the same scene from the same position on a fixed tripod, using the exact same lens. Both shot using a Leica 90mm Summarit lens set at 2.8. Shooting distance was 1 meter at an angle of approximately 45 degrees. Photos shot in RAW opened in Lightroom and exported at 900 pixels. There is no cropping. Focus point is on the middle "0" in "500".

Leica M9, 90mm Summarit @2.8.

Join to see EXIF info for this image (if available)

Panasonic GH2 with aspect ratio set to 3:2, Leica Summarit 90mm and CV m to 4/3 adaptor @ 2.8

Join to see EXIF info for this image (if available)

Doesn't matter which way you cut it DOF is not the same in these two images.

And just for fun. Here is a shot from the Panasonic/Leica 45mm macro lens @ 2.8 on the GH2.

Join to see EXIF info for this image (if available)

Again. Different DOF.

It's late. I'm off to bed.

Gordon

Thanks for finding and sharing these images Gordon, Don't you see the point now!

The very negligble difference in Dof in first two photos possibly can be of an error due to different body sizes and because of that to the distances between the focal plane. As from the test data, I can read its only one meter, where every small error can extend to couple of mm easily.

BUT THE POINT IS how similar is this difference? Is it anything close to what your Dof calculators were showing? Probably their numbers were as the third image (45mm 2.8 vs 90mm 2.8) to match the FOV. If you can write the measurements on the scale where you can see the sharp focus it will further help. And actually if you took these photos, you could actually crop the fullframe to see it even more clearly where the blur starts at both ends.

To me it looks: 482-512 vs 490-525 which is roughly 30 - 35 units while according to the origional arguments you posted, it should be double 30-60 or something like that.

...crop sensors don't "magnify" an image vs. full-frame for a given lens.

True, they just crop it in the center.

What this overlooks is that in order to get the same final print size, the crop captures have to be blown up more, which makes any blur look more blurred. Gordon's example above demonstrates this point.

Yes and it was intentional, to keep it simple, just wanted to speak about how the image is cropped on the focal plane and not how you output it on digital or print media. Where the blurred area will look more but relative to the sharp focal point .. their proportion will still remain same.
Yes, also agree on your point of more effective reach.

This is why I think the theory that (to give one example), a 25mm f.14 m4/3 is the same as a 50mm f2.8 full-frame in terms of angle-of-view and depth-of-field is an over-simplification. That is, the depth-of-field bit is an over-simplification, not the angle-of-view.

Once again you impressed me with your short but effective statement. Cheers!

... It's late. I'm off to bed. Gordon

Have a good sleep Godon! I ruined mine, been calculting Dof with your Dof charts and calculators in dreams!

For some one new to this thread, I would suggest reading this link as its very simple to understand this concept, Dof depends only on apperture and magnification (focal length and the distance to subject):
Sensor Size and Depth of Field « Shootin' The Shot

 

[Luckypenguin]

He he, this has all gotten very complicated. I just like taking pictures with whatever camera I have with me, which more often than not for me is a m4/3 camera. I don't necessarily find the slightly deeper depth-of-field of m4/3 vs APS-C to be an advantage or disadvantage. Sometimes yes, sometimes no. Each class of camera has it's own signature (and each brand and often model as well), but lens selection and post-processing procedures can blur the line significantly to the point where it is not always immediately obvious what camera took what image.

 

[BBW]

I just like taking pictures with whatever camera I have with me.

Me, too, Nic.

 

[Andrewteee]

He he, this has all gotten very complicated. I just like taking pictures with whatever camera I have with me.

+1