Rethinking 4/3 Depth Of Field

Started Apr 11, 2013 | Discussions
Rriley
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Re: I'm not convinced...
In reply to Great Bustard, Apr 12, 2013

Great Bustard wrote:

Anders W wrote:

I had a go at something like that here (click on "show signature" to see the entire post; I made a mistake of including a dashed line and ... ).

http://www.dpreview.com/forums/post/50462878

Not saying that's ideal in all regards but that was what I could manage.

Well, based on those samples, the EM5 has the clear edge.

For my personal/wants needs, there aren't a whole lot of pictures that would benefit from (or "tolerate") much less DoF than I get when I shoot my fast MFT primes (12/2, 20/1.7, 45/1.8, 75/1.8) wide open, although as you know I am less fond of background blur with very fast WAs than you are. That said, exceptions do of course exist. See example below.

Ironically, I think shallow DOF with UWA is "da bomb":

24mm FF isnt UWA

http://www.dpreview.com/forums/post/38116367

To that end, I think it would be interesting to see a comparison with competently processed photos.

P.S.:  I think the EM5 would come out significantly ahead in situations where it could use IBIS and a longer shutter speed and FF could not use a tripod.

And, yes, don't forget the awesome IBIS in the EM5.

I am not since I strongly appreciate it. In all fairness though, you can get IBIS with FF too if you get yourself an A99 (although I am not sure whether the efficiency matches that of the E-M5). And below is an example of an image that we have discussed before where an FF-camera with IBIS would beat the E-M5 with IBIS. As you can see, this is with the 12 mm at f/2 and 0.4 s. But the scene is sufficiently far away that one could have used a 24/1.4 on FF and still have sufficient DoF.

Thing is, though, that at such wide apertures, the corners suffer.  So, for low light wide aperture photography where corners matter (e.g. astrophotography), FF still has ample room for improvement.

And no, tripod-friends, a tripod would not have helped here. I was standing on a staircase that was constantly vibrating due to the traffic on the bridge to which it was connected.

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Riley
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Rriley
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Exposure is dominant
In reply to Great Bustard, Apr 12, 2013

Great Bustard wrote:

Alumna Gorp wrote:

Great Bustard wrote:

Alumna Gorp wrote:

Have a read at this.

http://admiringlight.com/blog/full-frame-equivalence-and-why-it-doesnt-matter/2/

...and made a few notes on some of his opinions:

http://www.dpreview.com/forums/post/50805880

No bleeding you again

That's right -- I had forgotten we had crossed paths before:

http://www.dpreview.com/forums/post/51210089

By the way, here's a current case-in-point as to why an understanding of Equivalence is useful for many:

http://www.dpreview.com/forums/post/51275066

Seems that f/2.8 isn't f/2.8 after all, eh? 

at some point some lenses will
where DoF is settled to be satisfactory as opposed to absolute, and 2.8 (in this case) is the minimum aperture a lens offers, 2.8 does indeed = 2.8

astro is a good example, where stars are so far away that f/2.8 lens can be set to infinity and no closer DoF need be considered. And as it happens there is a shutter speed limit of 20 seconds before stars becomes lines or streaks.

Exposure is dominant in such a calculation, and DoF is deemed achievable and satisfactory

If for some reason greater DoF is required (including part of a landscape) smaller sensors are likely to benefit from this restraint having inherently greater DoF, for a given shutter speed and limited widest aperture (f/2.8).

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Just another Canon shooter
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Re: Rethinking 4/3 Depth Of Field
In reply to Ken Strain, Apr 12, 2013

Ken Strain wrote:

PM2: Olympus 75mm lens at f/2.5, two exposures, one near-equivalent to the D800 shot, the other as I would normally have exposed it to give a similar raw histogram (+2/3 stop), i.e. shutter speeds of 1/180 and 1/125s.

Should be the same shutter speeds.

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Ken Strain
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Re: Rethinking 4/3 Depth Of Field
In reply to Just another Canon shooter, Apr 12, 2013

Just another Canon shooter wrote:

Ken Strain wrote:

PM2: Olympus 75mm lens at f/2.5, two exposures, one near-equivalent to the D800 shot, the other as I would normally have exposed it to give a similar raw histogram (+2/3 stop), i.e. shutter speeds of 1/180 and 1/125s.

Should be the same shutter speeds.

It is not clear what you mean by that phrase.

1/200th and 1/180th are surely close enough given the other uncertainties.  The significantly different exposure at 1/125th also represents a perfectly reasonable alternative choice, given how sensor saturation and ISO-setting scale factor were set on the PM2.  When I use the cameras I normally expose this way (i,e. relative to saturation level), though as I said not at ISO1600.

Ken

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Great Bustard
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Re: I'm not convinced...
In reply to Rriley, Apr 12, 2013

Rriley wrote:

Ironically, I think shallow DOF with UWA is "da bomb":

24mm FF isnt UWA

I've always thought that 24mm (on FF) was the long end of UWA:

http://www.cambridgeincolour.com/tutorials/wide-angle-lenses.htm

The definition of ultra-wide is a little fuzzier, but most agree that this realm begins with focal lengths somewhere around 20-24 mm [on FF] and less.

If I'm in error on this point, I'd appreciate a link to a credible source with a "less fuzzy" definition.

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Great Bustard
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Re: I'm not convinced...
In reply to Anders W, Apr 12, 2013

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

I had a go at something like that here (click on "show signature" to see the entire post; I made a mistake of including a dashed line and ... ).

http://www.dpreview.com/forums/post/50462878

Not saying that's ideal in all regards but that was what I could manage.

Well, based on those samples, the EM5 has the clear edge.

For my personal/wants needs, there aren't a whole lot of pictures that would benefit from (or "tolerate") much less DoF than I get when I shoot my fast MFT primes (12/2, 20/1.7, 45/1.8, 75/1.8) wide open, although as you know I am less fond of background blur with very fast WAs than you are. That said, exceptions do of course exist. See example below.

Ironically, I think shallow DOF with UWA is "da bomb":

http://www.dpreview.com/forums/post/38116367

Yes, I know. I think you are an excellent photographer and you generally have stylistic ideals that I think are close to my own, but the shallow DoF effect does not work for me in most of those images although there might be a few exceptions.

How dare you, sir!  Shallow DOF *always* makes the photo better, and the more shallow the better! 

More seriously, I absolutely account for differences in taste, but, as you know, I have quite an affinity for shallow DOF photography.  And that's not because I shoot FF -- it's why I went FF.

All that said, it is often difficult for me to get a "successful" photo at the DOFs I shoot -- most suck.  It's just that the deeper DOF shot that I could have gotten easily enough rarely appeals to me (not that I don't shoot my fair share of pics with deeper DOF, of course).

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Great Bustard
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Re: Lovely pix and excellent presentation of your argument
In reply to Anders W, Apr 12, 2013

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Hen3ry wrote:

And my argument if it comes to that.

Razor thin depth of field is a by-product, an artifact of big apertures. They allow you to shoot in lower light but more often than not, the very shallow DoF is a damned nuisance.

For me, shallow DOF is the bomb, and I'm wide open, more often than not, regardless of the light.  That said, I don't expect others to have my tastes, but it's not like I never stop down:

http://www.dpreview.com/forums/post/39537128

Besides, and editor might use one or two thin depth of field shots in a publication, but s/he certainly didn’t want page after page of them -- they were showing what the world looked like, not some arty-farty extract of the world governed by a super large aperture.

Well, a modern compact, like the RX100 might be better still for many, and DPR has been showcasing many pros making good use of cell phones for published works.

Then the argument was switched around so that razor thin DoF was practically the raison d'etre for taking a picture. Of course, you had to have the most expensive lens to achieve it so ordinary mortals were excluded.

There are quite a few fast primes for FF that aren't particularly expensive:  35 / 2, 50 / 1.8, 50 / 1.4, 85 / 1.8, 100 / 2.

On the other hand, many of those that aren't particularly expensive aren't very good wide open and thereabout. I am not saying that exceptions do not exist, but they are hardly frequent. Most of the fast Oly & Pany MFT primes, by contrast, do very well already from the get-go, and at least some of them are quite affordable too (20/1.7, 45/1.8).

Well, I guess it depends on what you mean by "aren't very good wide open" -- I found the 50 / 1.4:

http://www.dpreview.com/forums/post/34489299

85 / 1.8:

http://www.dpreview.com/forums/post/34631434

and 100 / 2:

http://www.josephjamesphotography.com/lenses/100f2/

more than "good enough", although that's not to say that I would not be against paying more for better still.  Indeed, I paid a lot more for the 50 / 1.2L:

http://www.josephjamesphotography.com/lenses/50L/

but I have to wonder how many, if anyone, appreciates the difference.

My definition of "not very good" is something like "significantly worse than peak performance".

Hmm.  My definition of "not very good" would be more like "doesn't deliver desired results".

Most MFT lenses are just marginally worse wide open than at peak, which they typically reach at f/4 in the center and at f/4 or f/5.6 at the edges. Since I want to use the really wide apertures far more often with MFT, due to the DoF "bonus", this is a blessing (and one of the things that convinced me to take the plunge).

I think in terms of the resolution of the final photo for a given DOF.  That is, if f/4 on mFT outperforms f/8 on FF, or f/2 on mFT outperforms f/4 on FF, then I would consider the mFT combo to be superior.

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Great Bustard
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Re: I like shallow DOF occasionally, and it can be done cheap on FT...
In reply to Hen3ry, Apr 12, 2013

Hen3ry wrote:

Look at the pair of you -- Roel & Bustard, like the old Pat & Mike comedy acts.

Who are you calling old?! 

Okay, Bustard, you miss a point I was trying to make: the very bright lenses I was referring too which cost a fortune -- that was back in the day, the 60s and 70s, even into the 80s. They are cheap now, comparatively.

The point was the ability to get good focus manually was dependent on having a bright lens on an SLR so they were in big demand -- but not necessarily to actually take the picture.

Don't know about film (never shot it), but for modern DSLRs, anything brighter than f/4 doesn't result in a brighter viewfinder.  In addition, anything faster than f/5.6 still uses f/5.6 AF points with no additional advantage (in terms of lens brightness), and anything faster than f/2.8 still uses f/2.8 AF points (again, with no additional advantage for brighter lenses).

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ultimitsu
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Re: Rethinking 4/3 Depth Of Field
In reply to al_in_philly, Apr 12, 2013

al_in_philly wrote:

Of course, I could shoot FF at 2.8, but then I'd also be shooting at an ISO of 12800 for the same shutter speed.

No, that is not the correct. At F1.4 all digital cameras lose about 40% of light. F1.2 lose about 50% and F1.8 loses about 10%. See DXO's F-stop blues article for more detail.  So for the same shot at the same SS, FF shoot at F2.8 would only need ISO 7000, rather than 12800.

Even as good as FF images are, the OM-D at 1/4 the ISO will always look better.

These is no basis for this claim.  OMD does not use alien technology, it uses a Sony sensor, which sports the same technology as D600, D800, A99 and RX1. so if its sensor size is 1/4, then at 1/4 iso it will look exactly the same IQ wise.

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Great Bustard
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It really isn't.
In reply to Rriley, Apr 12, 2013

Rriley wrote:

Great Bustard wrote:

Alumna Gorp wrote:

Great Bustard wrote:

Alumna Gorp wrote:

Have a read at this.

http://admiringlight.com/blog/full-frame-equivalence-and-why-it-doesnt-matter/2/

...and made a few notes on some of his opinions:

http://www.dpreview.com/forums/post/50805880

No bleeding you again

That's right -- I had forgotten we had crossed paths before:

http://www.dpreview.com/forums/post/51210089

By the way, here's a current case-in-point as to why an understanding of Equivalence is useful for many:

http://www.dpreview.com/forums/post/51275066

Seems that f/2.8 isn't f/2.8 after all, eh? 

at some point some lenses will
where DoF is settled to be satisfactory as opposed to absolute, and 2.8 (in this case) is the minimum aperture a lens offers, 2.8 does indeed = 2.8

No, it's just the best that it can do.

astro is a good example, where stars are so far away that f/2.8 lens can be set to infinity and no closer DoF need be considered. And as it happens there is a shutter speed limit of 20 seconds before stars becomes lines or streaks.

Exposure is dominant in such a calculation, and DoF is deemed achievable and satisfactory

But even when DOF doesn't matter (either because we don't care, or the whole of the scene is well within the DOF even at wide apertures), it's still not about exposure, but about the total amount of light collected:

Total Light Collected = Exposure x Effective Sensor Area x QE

So, exposure is relevant only inasmuch as it is a component of the total light collected.

If for some reason greater DoF is required (including part of a landscape) smaller sensors are likely to benefit from this restraint having inherently greater DoF, for a given shutter speed and limited widest aperture (f/2.8).

Smaller sensor systems have not "inherently greater DOF" except when we are in apertures deep into diffraction territory (past f/22 equivalent on FF).  For example, if someone is shooting f/8 on mFT for DOF reasons, then the FF photographer would simply shoot f/16.

On the other hand, if the mFT photographer was shooting f/22, the FF photographer cannot shoot f/44 (f/45), so the mFT system would have a DOF advantage.  That said, if "high IQ" is important, then both the mFT and FF photographers would make use of focus stacking, which, incidentally, was just discussed in a nice article here on DPR:

http://www.dpreview.com/articles/5717972844/focus-stacking-in-macro-photography

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Great Bustard
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Re: Rethinking 4/3 Depth Of Field
In reply to ultimitsu, Apr 13, 2013

ultimitsu wrote:

al_in_philly wrote:

Of course, I could shoot FF at 2.8, but then I'd also be shooting at an ISO of 12800 for the same shutter speed.

No, that is not the correct. At F1.4 all digital cameras lose about 40% of light. F1.2 lose about 50% and F1.8 loses about 10%. See DXO's F-stop blues article for more detail.  So for the same shot at the same SS, FF shoot at F2.8 would only need ISO 7000, rather than 12800.

The light loss is generally only an issue for f-ratios below f/2, and is a direct result of the efficiency of the microlens covering.  DxOMark's article did not measure mFT sensors, nor have they measured the latest generation of sensors.  In other words, today's micolenses may be more efficient than the last generation.

Even as good as FF images are, the OM-D at 1/4 the ISO will always look better.

These is no basis for this claim.  OMD does not use alien technology, it uses a Sony sensor, which sports the same technology as D600, D800, A99 and RX1. so if its sensor size is 1/4, then at 1/4 iso it will look exactly the same IQ wise.

It has less read noise / area at high ISOs than most FF DSLRs (the Canon 6D, however, matches it), and the same QE, which puts it slightly ahead of most FF DSLRs for Equivalent photos.

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Anders W
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Re: Rethinking 4/3 Depth Of Field
In reply to ultimitsu, Apr 13, 2013

ultimitsu wrote:

al_in_philly wrote:

Of course, I could shoot FF at 2.8, but then I'd also be shooting at an ISO of 12800 for the same shutter speed.

No, that is not the correct. At F1.4 all digital cameras lose about 40% of light.

All digital cameras? Was there any MFT camera in that test of DxO?

F1.2 lose about 50% and F1.8 loses about 10%. See DXO's F-stop blues article for more detail.  So for the same shot at the same SS, FF shoot at F2.8 would only need ISO 7000, rather than 12800.

Even as good as FF images are, the OM-D at 1/4 the ISO will always look better.

These is no basis for this claim.  OMD does not use alien technology, it uses a Sony sensor, which sports the same technology as D600, D800, A99 and RX1. so if its sensor size is 1/4, then at 1/4 iso it will look exactly the same IQ wise.

Does it? Did you check the DR curve for the A99 versus the E-M5?

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Anders W
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Re: Rethinking 4/3 Depth Of Field
In reply to Great Bustard, Apr 13, 2013

Great Bustard wrote:

ultimitsu wrote:

al_in_philly wrote:

Of course, I could shoot FF at 2.8, but then I'd also be shooting at an ISO of 12800 for the same shutter speed.

No, that is not the correct. At F1.4 all digital cameras lose about 40% of light. F1.2 lose about 50% and F1.8 loses about 10%. See DXO's F-stop blues article for more detail.  So for the same shot at the same SS, FF shoot at F2.8 would only need ISO 7000, rather than 12800.

The light loss is generally only an issue for f-ratios below f/2, and is a direct result of the efficiency of the microlens covering.  DxOMark's article did not measure mFT sensors, nor have they measured the latest generation of sensors.  In other words, today's micolenses may be more efficient than the last generation.

Even as good as FF images are, the OM-D at 1/4 the ISO will always look better.

These is no basis for this claim.  OMD does not use alien technology, it uses a Sony sensor, which sports the same technology as D600, D800, A99 and RX1. so if its sensor size is 1/4, then at 1/4 iso it will look exactly the same IQ wise.

It has less read noise / area at high ISOs than most FF DSLRs (the Canon 6D, however, matches it), and the same QE, which puts it slightly ahead of most FF DSLRs for Equivalent photos.

Thanks Joe. I like your brutal honesty!

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Detail Man
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Re: I'm thinking of topping myself ...
In reply to Michael J Davis, Apr 13, 2013

Michael J Davis wrote:

...yet another DoF thread & more nonsense!

... I expect!

So true, Michael. All that exists is some perceptual Circle of Confusion from which extrapolations are made to and fro in object-space. In the end, likely nearly all just guess in the field (and/or believe preview-screens). Once again, the deeply complicated extrapolations (for all but close-up/macro):

Hyperfocal Distance (in units of Meters):

HFD = (L^2 / (FC) ) + L

where:

L is the Focal Length (in units of milliMeters);

F is F-Number;

C is COC diameter (in units of Microns)

.

Depth of Field (in units of Meters):

DOF = (2D) / ( HFD/D - D/HFD )

where:

D is Camera to Subject Distance (front nodal plane to plane of focus);

HFD is Hyperfocal Distance.

.

Approximate DOF (maximum 11% error on the low side at 1/3 of the Hyperfocal Distance):

DOF ~ (2FC) * (D/L)^2

where:

F is F-Number;

C is COC diameter (in units of Microns);

D is Camera to Subject Distance (front nodal plane to plane of focus);

L is the Effective Focal Length (in units of milliMeters).

.

Relative Background Blur:

BP ~ ( (100) / ( (F) (H) ) ) * ( (L)^(2) ) * ( ( Df - D ) / ( (Df) (D) ) )

where:

BP is the percentage of the image-frame diagonal that the blur-disk represents;

F is F-Number;

H is the diagonal dimension of the image-sensor's active-area;

L is the Focal Length (when focused at infinity);

D is the Camera (front nodal-plane) to Subject (plane-of focus) Distance;

Df is the Camera (front nodal-plane) to Background Subject Matter Distance.

.

Under Constant Framing (FOV) Conditions (when D is the same; when Df and D are the same):

DOF2 / DOF1 = ( F2 / L2) / ( F1 / L1 ) = A2 / A1

BP2 / BP1 = ( F1 / L1 ) / ( F2 / L2) = A1 / A2

where A is the virtual aperture (entrance pupil) diameter.

.

Under Constant DOF Conditions:

The virtual aperture (entrance pupil) diameter being the same, the Total Light is the same, and different sensor sizes perform the same - except Photon Shot Noise will vary by the square-root of the Quantum Efficiencies, and Read Noise will vary in ways determined more by the image-sensor's individual design than other factors (which makes comparisons largely camera test-data specific).

.

Now that the mathematics and sensor process variables prove to be either too formidable, or unknown without test data, we can go back to guessing and peering at tiny preview-screens.

DM ...

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Anders W
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Re: Lovely pix and excellent presentation of your argument
In reply to Great Bustard, Apr 13, 2013

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Hen3ry wrote:

And my argument if it comes to that.

Razor thin depth of field is a by-product, an artifact of big apertures. They allow you to shoot in lower light but more often than not, the very shallow DoF is a damned nuisance.

For me, shallow DOF is the bomb, and I'm wide open, more often than not, regardless of the light.  That said, I don't expect others to have my tastes, but it's not like I never stop down:

http://www.dpreview.com/forums/post/39537128

Besides, and editor might use one or two thin depth of field shots in a publication, but s/he certainly didn’t want page after page of them -- they were showing what the world looked like, not some arty-farty extract of the world governed by a super large aperture.

Well, a modern compact, like the RX100 might be better still for many, and DPR has been showcasing many pros making good use of cell phones for published works.

Then the argument was switched around so that razor thin DoF was practically the raison d'etre for taking a picture. Of course, you had to have the most expensive lens to achieve it so ordinary mortals were excluded.

There are quite a few fast primes for FF that aren't particularly expensive:  35 / 2, 50 / 1.8, 50 / 1.4, 85 / 1.8, 100 / 2.

On the other hand, many of those that aren't particularly expensive aren't very good wide open and thereabout. I am not saying that exceptions do not exist, but they are hardly frequent. Most of the fast Oly & Pany MFT primes, by contrast, do very well already from the get-go, and at least some of them are quite affordable too (20/1.7, 45/1.8).

Well, I guess it depends on what you mean by "aren't very good wide open" -- I found the 50 / 1.4:

http://www.dpreview.com/forums/post/34489299

85 / 1.8:

http://www.dpreview.com/forums/post/34631434

and 100 / 2:

http://www.josephjamesphotography.com/lenses/100f2/

more than "good enough", although that's not to say that I would not be against paying more for better still.  Indeed, I paid a lot more for the 50 / 1.2L:

http://www.josephjamesphotography.com/lenses/50L/

but I have to wonder how many, if anyone, appreciates the difference.

My definition of "not very good" is something like "significantly worse than peak performance".

Hmm.  My definition of "not very good" would be more like "doesn't deliver desired results".

I am not sure the two definitions are very different.

Most MFT lenses are just marginally worse wide open than at peak, which they typically reach at f/4 in the center and at f/4 or f/5.6 at the edges. Since I want to use the really wide apertures far more often with MFT, due to the DoF "bonus", this is a blessing (and one of the things that convinced me to take the plunge).

I think in terms of the resolution of the final photo for a given DOF.  That is, if f/4 on mFT outperforms f/8 on FF, or f/2 on mFT outperforms f/4 on FF, then I would consider the mFT combo to be superior.

Outperforms and outperforms. How about roughly equivalent.

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Re: I'm not convinced...
In reply to Great Bustard, Apr 13, 2013

Great Bustard wrote:

Rriley wrote:

Ironically, I think shallow DOF with UWA is "da bomb":

24mm FF isnt UWA

I've always thought that 24mm (on FF) was the long end of UWA:

http://www.cambridgeincolour.com/tutorials/wide-angle-lenses.htm

The definition of ultra-wide is a little fuzzier, but most agree that this realm begins with focal lengths somewhere around 20-24 mm [on FF] and less.

If I'm in error on this point, I'd appreciate a link to a credible source with a "less fuzzy" definition.

I am not usually inclined to propose definite limits of anything, but 24 is to me precisely the border line between WA and UWA.

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Re: I'm not convinced...
In reply to Great Bustard, Apr 13, 2013

Great Bustard wrote:

Anders W wrote:

Great Bustard wrote:

Anders W wrote:

I had a go at something like that here (click on "show signature" to see the entire post; I made a mistake of including a dashed line and ... ).

http://www.dpreview.com/forums/post/50462878

Not saying that's ideal in all regards but that was what I could manage.

Well, based on those samples, the EM5 has the clear edge.

For my personal/wants needs, there aren't a whole lot of pictures that would benefit from (or "tolerate") much less DoF than I get when I shoot my fast MFT primes (12/2, 20/1.7, 45/1.8, 75/1.8) wide open, although as you know I am less fond of background blur with very fast WAs than you are. That said, exceptions do of course exist. See example below.

Ironically, I think shallow DOF with UWA is "da bomb":

http://www.dpreview.com/forums/post/38116367

Yes, I know. I think you are an excellent photographer and you generally have stylistic ideals that I think are close to my own, but the shallow DoF effect does not work for me in most of those images although there might be a few exceptions.

How dare you, sir!  Shallow DOF *always* makes the photo better, and the more shallow the better! 

With your permission sir, I think many of those are excellent shots that would have become still more excellent with slightly more DoF. That said, as already indicated, it does occasionally work.

More seriously, I absolutely account for differences in taste, but, as you know, I have quite an affinity for shallow DOF photography.  And that's not because I shoot FF -- it's why I went FF.

All that said, it is often difficult for me to get a "successful" photo at the DOFs I shoot -- most suck.  It's just that the deeper DOF shot that I could have gotten easily enough rarely appeals to me (not that I don't shoot my fair share of pics with deeper DOF, of course).

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Martin.au
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Re: Rethinking 4/3 Depth Of Field
In reply to Ken Strain, Apr 13, 2013

Ken Strain wrote:

Just another Canon shooter wrote:

Ken Strain wrote:

PM2: Olympus 75mm lens at f/2.5, two exposures, one near-equivalent to the D800 shot, the other as I would normally have exposed it to give a similar raw histogram (+2/3 stop), i.e. shutter speeds of 1/180 and 1/125s.

Should be the same shutter speeds.

It is not clear what you mean by that phrase.

1/200th and 1/180th are surely close enough given the other uncertainties.  The significantly different exposure at 1/125th also represents a perfectly reasonable alternative choice, given how sensor saturation and ISO-setting scale factor were set on the PM2.  When I use the cameras I normally expose this way (i,e. relative to saturation level), though as I said not at ISO1600.

Ken

The 1/180 and 1/200 "equivalent" exposures don't look very equivalent. The D800 shot looks awful.

Would you mind shooting a few more images.

Using exactly the same shutter speed settings (so people can't complain) and equivalent ISO and aperture, shoot the OM-D at 1600 and the D800 at 3200 and 6400.

Then possibly post the full pictures, rather than just crops?

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Just another Canon shooter
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Re: Rethinking 4/3 Depth Of Field
In reply to Martin.au, Apr 13, 2013

Mjankor wrote:

The 1/180 and 1/200 "equivalent" exposures don't look very equivalent. The D800 shot looks awful.

Would you mind shooting a few more images.

Using exactly the same shutter speed settings (so people can't complain) and equivalent ISO and aperture, shoot the OM-D at 1600 and the D800 at 3200 and 6400.

Then possibly post the full pictures, rather than just crops?

Also, something colorful with detail. Most of the D800 noise is chroma, in the reds. But the D800 image has more saturated reds in the first palace.

Another variable is the lenses used. The zoom is likely to be darker than the prime.

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Rriley
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Re: It really isn't.
In reply to Great Bustard, Apr 13, 2013

Great Bustard wrote:

Rriley wrote:

Great Bustard wrote:

Alumna Gorp wrote:

Great Bustard wrote:

Alumna Gorp wrote:

Have a read at this.

http://admiringlight.com/blog/full-frame-equivalence-and-why-it-doesnt-matter/2/

...and made a few notes on some of his opinions:

http://www.dpreview.com/forums/post/50805880

No bleeding you again

That's right -- I had forgotten we had crossed paths before:

http://www.dpreview.com/forums/post/51210089

By the way, here's a current case-in-point as to why an understanding of Equivalence is useful for many:

http://www.dpreview.com/forums/post/51275066

Seems that f/2.8 isn't f/2.8 after all, eh? 

at some point some lenses will
where DoF is settled to be satisfactory as opposed to absolute, and 2.8 (in this case) is the minimum aperture a lens offers, 2.8 does indeed = 2.8

No, it's just the best that it can do.

astro is a good example, where stars are so far away that f/2.8 lens can be set to infinity and no closer DoF need be considered. And as it happens there is a shutter speed limit of 20 seconds before stars becomes lines or streaks.

Exposure is dominant in such a calculation, and DoF is deemed achievable and satisfactory

But even when DOF doesn't matter (either because we don't care, or the whole of the scene is well within the DOF even at wide apertures), it's still not about exposure, but about the total amount of light collected:

exposure is the only governance left if DoF doesnt matter

Total Light Collected = Exposure x Effective Sensor Area x QE

So, exposure is relevant only inasmuch as it is a component of the total light collected.

'exposure is relevant only inasmuch as it is a component of the total light collected' - ridiculous long winded pedantry,  - 'exposure is the relevant component of the light collected'

If for some reason greater DoF is required (including part of a landscape) smaller sensors are likely to benefit from this restraint having inherently greater DoF, for a given shutter speed and limited widest aperture (f/2.8).

Smaller sensor systems have not "inherently greater DOF" except when we are in apertures deep into diffraction territory (past f/22 equivalent on FF).  For example, if someone is shooting f/8 on mFT for DOF reasons, then the FF photographer would simply shoot f/16.

why do you imagine anything else that what Ive given
the restraint is an exposure 20 secs or less as fstops at any aperture are immaterial
given that, what on earth do you think you would be doing shooting at f/22

On the other hand, if the mFT photographer was shooting f/22, the FF photographer cannot shoot f/44 (f/45), so the mFT system would have a DOF advantage.  That said, if "high IQ" is important, then both the mFT and FF photographers would make use of focus stacking, which, incidentally, was just discussed in a nice article here on DPR:

you dont seem to grasp what the issues are here.
you dont get the opportunity for more than one exposure as the earth has rotated relative to the ground, ie the sky ~ 'stars' are now in another location, another exposure is worthless

http://www.dpreview.com/articles/5717972844/focus-stacking-in-macro-photography

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