Potential dead horse: how bad is FF's deep DoF disadvantage?

Started Mar 5, 2014 | Discussions
Steen Bay Veteran Member • Posts: 6,974
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?

Bill Robb wrote:

sportyaccordy wrote:

DoF is entirely a product of the aperture diameter.

You need to go back to school if you think this.

Depends a bit on FL and distance too (guess the OP was assuming equivalent FLs and fixed distance).

gandalfII Senior Member • Posts: 1,952
That's what tilt/shift lenses are for (nt)

No text.

joejack951 Senior Member • Posts: 2,682
Re: no disadvantage

Steen Bay wrote:

joejack951 wrote:

tko wrote:

And I own a FF lens that stops down to F/50 or something silly.

What lens? My 105VR will display f/57 when stopped down to f/22 and at minimum focusing distance, but that's just Nikon's way of displaying the light loss at close focus distances (effective aperture as explained in the lens manual). DoF is still f/22.

If you shoot af f/22 at 1:1 magnification, then I think that you're effectively shooting at app. f/44 in terms of both exposure, DoF and diffraction. Kind of like using a 2x TC.

I misspoke when I said f/22. The 105VR stops down to f/32 and will display f/57 (IIRC) at minimum focusing distance.

Unless I've always read/understood incorrectly, effective aperture only affects exposure. DoF and diffraction are not affected because the aperture blades aren't actually moving. TC's have glass in them that changes the image being projected by the lens. That's a lot different than moving the lens elements further from the sensor (like an extension tube).

I swear that my lens manual went into detail about this but the Nikon lens manual online mentions nothing about effective aperture. Weird. I need to check that when I get home.

Any care to chime in on the true effects of shooting up close?

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Erik Magnuson Forum Pro • Posts: 12,247
Re: no disadvantage

joejack951 wrote:

I don't know of any full frame lenses that go smaller than f/32.

Not for Nikon. The Sigma 50mm macro goes to f/45 in some mounts.  Of course, adding a TC can also make for smaller f/stops.

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Erik

Karaya Senior Member • Posts: 2,036
Here is some sample shots.

I shoot both Olympus 4/3 and Canon FF. I like both and use 4/3 for my nature - wildlife shooting and FF for most of my people - landscape shooting.

For people shooting, in particular, I am not entirely convinced of the supposed FF advantage. I use a 85mm L f1.2 lens and usually have auto ISO engaged on my 5DMKIII, a potent combination for low light shooting, however, I often have to stop down to get adequate DOF with a corresponding bump in ISO. This is potentially a disadvantage versus smaller formats. Here are two examples:

In the above photo I had to stop down to f7.1 to get enough DOF for the text on the wall to be legible, so the ISO went to 2000. A 4/3 camera could have given me the same shutter speed and DOF @ f3.6 and ISO 500. So which camera will have better image quality - 4/3 @ iso 500 or FF @ iso 2000? That would, of course depend on the camera, but an EM-1 at iso 500 should look good compared to any FF at iso 2000.

Here is another coffee shop example showing how razor thin the DOF can be on FF. In less then full length portraits opening up to less then f2 with FF becomes very challenging. You can end up with nothing but one eye perfectly sharp. Given a really fast and sharp 4/3 lens, like the voigtlander 45 f.95 this shot could have been done with a 4/3 camera at F 1, 1/125 and ISO 100.

So, given really fast primes that are sharp wide open much of the IQ advantage of FF vs smaller formats disappears. If you prefer zooms then FF would still have all the Aces. Of course such über fast primes are hardly inexpensive or convenient!

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GeraldW Veteran Member • Posts: 7,744
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?
1

Back in the days when I was shooting 35 mm film, I sometimes found that achieving very deep DOF was difficult, particularly if a polarizing filter was used, as the small aperture and additional 2 stop loss from the polarizer pushed the limits of hand holding, even with ISO 400 film.

At Yosemite, shooting from Glacier Point, I was trying to get a nearby pine in focus, half dome at some distance, and the mountains in the far distance all in focus.  I was shooting hand held and at f/16 the resulting shutter speed was below 1/100 second.  It did come out OK, and the resulting print is still on my wall.

Taking that same shot today with something like my G15 would be much easier.

I'd also like to take this opportunity for a small rant.  There seems to be an obsession with bokeh and separating the background these days.  Back when I started this hobby in 1955; a lot more was being written about how to increase DOF, than there was about limiting it.  Sure, any text or paper on portraiture discussed DOF and the relation of the background.  But for most other subjects, the emphasis was on increasing the DOF.

Then, sometime in the 80's something called selective focus came into vogue.  Frankly, I didn't like the look, and still don't.  Now DPReview (and others) are showing graphs of equivalent f/# for smaller sensors.  I know it relates to equivalent DOF; but, unfortunatly I'm seeing a lot of posts on this site where people are taking those numbers as the equivalent f/# in terms of exposure, and cautioning about the slow shutter speeds that will result.  Enough already!

Overall, this has been an interesting thread.

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Jerry

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Mike Davis Contributing Member • Posts: 798
Re: Zero
1

Lee Jay wrote:

sportyaccordy wrote:

So my question is, for folks who have used an array of different formats extensively, how much does this affect real world shooting?

Not at all. As you pointed out, for constant (deep) depth of field, all formats are the same.

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Lee Jay

True, except that smaller formats operate at faster shutter speeds to yield the same DoF and diffraction at any given enlargement factor and desired print resolution, and confining the small-sensor photographer to use of smaller f-Numbers and, potentially, fewer diffraction-free f-Numbers from which to choose among those that are available on the lens.

Example:

12 MP Panasonic Lumix DMC-TS1

Sensor Size: 6.13 x 4.16 mm

Largest possible non-resampled 360 ppi (5lp/mm) print: 8.27 x 11.02 inches

Enlargement Factor: 45.67x

F-Number at which diffraction would begin to inhibit a desired print resolution of 5 lp/mm in the final print: f/3.2

Maximum aperture: f/3.3 - f/5.9 (variable across zoom range)

Conclusion: Other factors ignored, thanks to diffraction alone, this tiny 12MP sensor can only deliver 5 lp/mm worth of true subject detail in an 8.27 x 11.02-inch print when shot wide open at f/3.2, using its shortest focal length. The diffraction-savvy photographer therefore has a choice of exactly one FL and one f-Number if a print resolution of 5 lp/mm is desired, but at f/3.2, the DoF and diffraction will be identical to that had at f/17.7 with the larger sensor - at a proportionately faster shutter speed.

vs.

12 MP Nikon D3 or D700

Sensor Size: 36.0 x 23.9 mm (more than five times larger than the Lumix DMC-TS1 sensor)

Largest possible non-resampled 360 ppi (5lp/mm) print: 8.27 x 11.02 inches (same pixel count)

Enlargement Factor: 8.34x (less than 1/5th the Lumix DMC-TS1 enlargement factor)

F-Number at which diffraction would begin to inhibit a desired print resolution of 5 lp/mm in the final print: f/17.7 (more than five times larger than the f-Number at which diffraction would begin to inhibit a desired print resolution of 5 lp/mm with the Lumix DMC-TS1).

Conclusion: Other factors ignored, thanks to diffraction alone, this larger 12MP fullframe sensor can deliver 5 lp/mm worth of true subject detail in an 8.27 x 11.02-inch print when shot at any f-Number less than or equal to f/17.7. If this 12MP fullframe sensor is equipped with an interchangeable lens offering stops from f/3.2 to f/22, the diffraction-savvy photographer has a choice of six stops that would not inhibit a desired resolution of 5 lp/mm due to diffraction: f/3.2 through f/17.7. At f/17.7, the DoF and diffraction would be identical to that had at f/3.2 with the smaller er sensor - at a proportionately slower shutter speed.

Note that f-Numbers smaller than f/17.7 could only be used with the fullframe sensor when the intrinsic depth of the subject space does not require as much DoF, but with the smaller sensor, you have no choice but to shoot wide open at the shortest focal length, all the time - to prevent diffraction from inhibiting a desired resolution of 5 l/mm in a non-resampled 360 ppi print of the same dimensions.

Thus aside from signal-to-noise issues, the difference caused by diffraction, between large sensor and small sensor, all else being the same, is one of available f-Numbers from which to choose and the shutter speeds at which identical DoF and diffraction can be recorded.

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Mike Davis Contributing Member • Posts: 798
Re: Dust

Smaller sensors suffer greater enlargement factors to produce like-sized prints, and thus, dust at the sensor would suffer greater magnification (assuming like-sized dust particles).

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Erik Magnuson Forum Pro • Posts: 12,247
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?

GeraldW wrote:

Back when I started this hobby in 1955; a lot more was being written about how to increase DOF, than there was about limiting it.

Films were slow and precision focus aids were relatively expensive.

Then, sometime in the 80's something called selective focus came into vogue.

It always depended on what you shot:  if the situation involves isolating a subject against a busy background (i.e. sports, outdoor fashion or portraiture, etc.) then shallow DOF makes a difference.  It's also about what's practical or affordable: how well could you have even used a 135mm f/2 lens in 1955?

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Erik

OP sportyaccordy Veteran Member • Posts: 8,960
Re: Here is some sample shots.

This is exactly the kind of real-world example I was looking for. Thank you.

It's definitely not as straight forward as it seems. Though I am wondering how the photos would have come out with wider lenses, which would have deeper DoF for for a given F-stop, enabling faster shutter speeds.

Most of my shooting is on the wide end as I've just grown accustomed to using kit zooms... so I am wondering if these disadvantages would be as big of a deal for me. Something like a 24/2 or 35/2 would be awesome for me.

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OP sportyaccordy Veteran Member • Posts: 8,960
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?

Bill Robb wrote:

sportyaccordy wrote:

DoF is entirely a product of the aperture diameter.

You need to go back to school if you think this.

Sorry- all other things equal (field of view and distance to subject). A subject on an MFT with a 12mm at F2 will look exactly the same on an FF with a 24mm at F4, assuming the same resolution, sensor performance and FoV/DtS. Unless you have some examples of this not being true....

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enemjii Senior Member • Posts: 1,889
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?
1

Steen Bay wrote:

enemjii wrote:

Huh. I always thought a shallow DoF was what everyone is chasing with the larger sensors. The smaller sensors on a P&S literally have an infinity focus and a correspondingly deep DoF, which is why they have a fixed focus.

I'm not aware of any compacts with fixed focus (they all have AF).

"Focus-free lenses accomplish their magic by relying on depth-of-field and wide-angle optics....most fixed-focus lenses are calibrated to what is known as the hyperfocal distance. This is a photographic concept that establishes the closest distance to the lens that objects can remain in focus, while still maintaining sharpness at infinity."

http://www.picturecorrect.com/tips/what-is-a-fixed-focus-lens-in-photography/

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EinsteinsGhost
EinsteinsGhost Forum Pro • Posts: 11,977
Conversely

Your Sample # 1:
If it were deemed that the chair is somewhat a distraction, you could open up the aperture and go with a shallower DOF without compressing the background or changing perspective, now at a lower ISO as well. This is the FF advantage.

Your Sample # 2:
If f/2 equiv in that case is too shallow, it would be the same with f/1 on m43 as well, which means, now you have to stop down there as well. OTOH, it is not necessarily required that one must raise ISO everytime you stop down. Under most occasions, you won't increase ISO proportional to stopping down.

The larger sensor advantage is with being able to isolate without having to compress or change perspective. If your needs are the opposite, you could go with smaller sensors (APSc is my happy medium between small and large).

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enemjii Senior Member • Posts: 1,889
Re: example of fixed focus compact P&S

Here is an example of fixed focus compact P&S

http://camerapedia.wikia.com/wiki/Agfa_Click-I

Lens: Meniscus lens 72.5mm f/8.8 filter slip-on

Aperture: f/8.8 and f/11;

  • Focusing: fixed focus
  • Shutter: single speed rotary shutter, speed about 1/30
  • Synchronised for Agfa Clibo flash unit, attach buttons on the right of the top plate
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(unknown member) Veteran Member • Posts: 9,509
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?

sportyaccordy wrote:

So my question is, for folks who have used an array of different formats extensively, how much does this affect real world shooting? Did you ever find yourself frustrated with the inability to get deep DoF from larger formats, or is it not that big of a deal?

Real world.....

I find that for very close in shots like portraits in good light, DOF can be too shallow for my liking with FF and MFT can be useful wide open. Of course you can always stop down the FF lens and still get what I like.....just a bit easier with MFT.

Once you get even a bit of distance though and it is fine wide open and I much prefer FF.

EDIT..this photo would have been better a stop down but if you don't pixel peep would print ok..

Sony A7 and Canon FD 85 1.2 L at 1.2 as taken jpeg

It seems to me more and more like no format is superior to another... they all have advantages and disadvantages that make them better for different kinds of photography, with no clear all around winner

My FF A7 is my favourite camera for most things but for telephoto or macro, I prefer my MFT Panasonic GX7.

All systems have their for and against.

Erik Magnuson Forum Pro • Posts: 12,247
Re: Potential dead horse: how bad is FF's deep DoF disadvantage?
1

Steen Bay wrote:

I'm not aware of any compacts with fixed focus (they all have AF).

No longer common except for non-zoom cheap CMOS "toy" cameras like the Lego Camera.  But 15 years ago it was more common, e.g. Fuji MX-1200, Kodak DC-215.

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Erik

joejack951 Senior Member • Posts: 2,682
Re: Here is some sample shots.

Karaya wrote:

In the above photo I had to stop down to f7.1 to get enough DOF for the text on the wall to be legible, so the ISO went to 2000. A 4/3 camera could have given me the same shutter speed and DOF @ f3.6 and ISO 500. So which camera will have better image quality - 4/3 @ iso 500 or FF @ iso 2000? That would, of course depend on the camera, but an EM-1 at iso 500 should look good compared to any FF at iso 2000.

You could have also positioned her closer to the wall. I don't see anything preventing that other than perhaps your choice of focal length.

Here is another coffee shop example showing how razor thin the DOF can be on FF. In less then full length portraits opening up to less then f2 with FF becomes very challenging. You can end up with nothing but one eye perfectly sharp. Given a really fast and sharp 4/3 lens, like the voigtlander 45 f.95 this shot could have been done with a 4/3 camera at F 1, 1/125 and ISO 100.

The Voightlander 42.5mm f/0.95 is a $1000 manual focus lens. The Canon 85mm f/1.8 has ultrasonic AF and costs $419. It weighs a little less than the Voightlander lens, too, if that matters to you. Both are about the same size.

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Steen Bay Veteran Member • Posts: 6,974
Re: example of fixed focus compact P&S

enemjii wrote:

Here is an example of fixed focus compact P&S

http://camerapedia.wikia.com/wiki/Agfa_Click-I

Lens: Meniscus lens 72.5mm f/8.8 filter slip-on

Aperture: f/8.8 and f/11;

  • Focusing: fixed focus
  • Shutter: single speed rotary shutter, speed about 1/30
  • Synchronised for Agfa Clibo flash unit, attach buttons on the right of the top plate

Wouldn't call that a compact, that's a MF camera Have it myself, and many other fixed focus film cameras, but almost all compact digital cameras have AF. Maybe some (or most) phonecams have fixed focus lenses?

Erik Magnuson Forum Pro • Posts: 12,247
Re: Here is some sample shots.

Karaya wrote:

Given a really fast and sharp 4/3 lens, like the voigtlander 45 f.95 this shot could have been done with a 4/3 camera at F 1, 1/125 and ISO 100.

Only if the Voigtlander was sufficiently sharp at f/1. It's not. Lenstip.com: "It is clear that in the frame centre, at the maximum relative aperture, the image is still not fully useful. In order to improve it you have to stop down the lens near f/1.2. By f/1.4 the image quality can be already described as good and from f/2.0 upwards you deal with an excellent resolution level."

On Lentip's test, the Voigtlander does resolve about the same in lp/mm as the Canon 85mm at f/2. The problem is that a Canon FF has almost 2x the mm!

So, given really fast primes that are sharp wide open

Alas, that's not a given for really fast primes.

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Erik

Great Bustard Forum Pro • Posts: 39,699
Answer:
2

sportyaccordy wrote:

DoF is entirely a product of the aperture diameter. So a 24mm F4 will have the same DoF as 48mm F8, 12mm F2 etc etc.

For the same focal distance, display size, viewing distance, and visual acuity, yes.

As someone explained to me in another thread, for equivalent photos this phenomenon cancels out larger formats' high ISO advantage for completely equivalent pictures. For example to maintain shutter speeds, that 24mm F4 on an FF camera will need to be shot at 2 ISO stops higher than 12mm F2 on an MFT camera. At which point the noise on the FF is at best the same but in some cases worse if we are talking very high ISOs.

Correct. Equivalent photos (same DOF and shutter speed) are made from the same total amount of light, so the noise advantage will go to the system with the more efficient sensor.

However, this noise differential due to differences in sensor efficiency can be extended or closed based on how detailed the photo is. That is, the system that resolves more detail can make greater use of NR (noise reduction).

So my question is, for folks who have used an array of different formats extensively, how much does this affect real world shooting? Did you ever find yourself frustrated with the inability to get deep DoF from larger formats, or is it not that big of a deal?

It would depend heavily on the particular bodies being compared and the ISO being used. This post has some very interesting comparisons between FF and mFT based on the particular ISOs being used:

http://www.dpreview.com/forums/post/53170596

and this post:

http://www.dpreview.com/forums/post/53148569

shows an interesting comparison of FF vs mFT based on pixel count.

It seems to me more and more like no format is superior to another... they all have advantages and disadvantages that make them better for different kinds of photography, with no clear all around winner

One would take that as a given, I should think. In my personal opinion, differences between systems based on operation, size, weight, and price matter way, way, way more than differences based on IQ and DOF control for the vast majority.

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