Do you always use widest aperture for outdoor portraits?

[William W]

To be frank, although I expect that two stops down, nearly all of my lenses will be sharper than when wide open - I wouldn't know what an Aperture/Sharpness curve looked like for any of my lenses: I tested most of them in the field and then bought the ones which suited me to make photos, not to use as a lab experiment.

Sure, nearly all of the lenses that I have are 'fast' and some are 'extremely fast', and certainly none are at there sharpest wide open, but (also quoting the OP), for "outdoor portraits" the butterfly swimmer fulfilled the brief and was certainly sharp enough for both publication and sale - the shot didn't have be 'the sharpest technically possible' - not many shots do.

I think that, especially now in the digital world, there's a passion for the minutia of, for want of an all encompassing phrase - pixel peeping - and that is at the expense of what once was, the essence of Photography.

That's not a criticism, simply an observation: we each get joy from from different elements of The Craft - my joy basically, and predominately is: nailing The Shot.

WW

[Manfred M]

Agreed Bill and I often have to remind people that images should be viewed at a distance no closer than the diagonal of the image. When judging, we are instructed to view the images no closer than 2x - 3x the diagonal of the image. This goes for both digital images (i.e. projected on a screen) or prints.

I can 100% guarantee that at those distances, I cannot see any appreciable difference in resolution.

Last year I went to two exhibitions at two different galleries; one included the enormous images that Edward Burtynsky makes using a large scale chromogenic printer (this was at the National Gallery of Canada) and the other was an exhibition that one of my mentors (Jim Lamont) had at the City of Ottawa's Atrium Gallery. Jim's prints were done on a 44" Epson printer using Epson Hot Press Bright (cotton rag) paper.

I understand that Burtynsky is using a medium digital Hasselblad for much of his work, but is using drones, rather than aircraft / helicopters for his recent aerial shots. Jim is using a full-frame Nikon D850 and stitches (up to three frames wide with focus stacking, as needed).

When I pixel peep, all I will say is that Burtynsky's images are not made for pixel peepers while Lamont's are... Step back to the recommended viewing distances and the difference goes away quickly


To give an idea of the size of the prints;

1. Burtynsky's work at Anthropocene at the National Gallery of Canada




2. Jim Lamont with one of his larger panos at St Paul University, Ottawa show (January 2019)

[xpatUSA]

Agreed, Bill, and I often have to remind people that images should be viewed at a distance no closer than the diagonal of the image. When judging, we are instructed to view the images no closer than 2x - 3x the diagonal of the image. This goes for both digital images (i.e. projected on a screen) or prints.

I can 100% guarantee that at those distances, I cannot see any appreciable difference in resolution.<>

The judicial aspect is interesting as always, Manfred.

The instructions do seem close-ish to the viewing recommendations for HDTV, and the minimum distance is reminiscent of that often used as an example in DOF tutorials.

[Manfred M]

The judicial aspect is interesting as always, Manfred.

The instructions do seem close-ish to the viewing recommendations for HDTV, and the minimum distance is reminiscent of that often used as an example in DOF tutorials.

What is interesting as well is that the original HD standards worked well for the smallish homes that most Asians live in (i.e. Japan) and the newer 4K standards are more aligned for the larger North American rooms with TVs where people sit farther away. That being said, the number of 0.3 arc-minute for a pixel is the limit of human resolution seems to stick in my mind.

That being said, I have never seen a definitive study on how aging impacts our resolution. I know that colour vision deteriorates as we age but I don't know about resolution.

[xpatUSA]

<> That being said, the number of 0.3 arc-minute for a pixel is the limit of human resolution seems to stick in my mind.

Yes, the oft-quoted average due to Snellen is 1 arc-minute but most people can do better than that according to Helmholtz, so that number could indeed be about right:

https://www.healio.com/ophthalmology...e-of-human-eye

There, it says:

"What is the best documented Snellen visual acuity? The limit of best corrected Snellen visual acuity is 20/8.9 (2.25 times better than 20/20), as shown in a study published in 1996 in the American Journal of Ophthalmology about the Los Angeles Dodgers."

[William W]

^ Aside: I love it when you guys start to talk technical - it brings out the Music of Mathematics deep within me.
It is even better when you link to papers I can read.
We need to get a virtual "Bar", I reckon the technical conversation would surely be interesting in the wee hours, post a few drams.

[Chataignier]

David / Bill - While that may be true, no one that I know who buys fast lenses does so with the intent of always stopping down to maximize resolution. We buy them so that we can shoot them wide open and frankly they are designed to give good results used that way. We could have saved a lot of money (and weight) opting for a slower lens.

What is a fast lens? For a zoom f/2.8 or faster. For a fixed focal length lens, f/1.4 and faster.

It's not just about resolution, but also low light performance and shallow depth of field. People seem to ignore that and concentrate on resolution.

Of course it's not just about resolution, but it's not just about shallow depth of field either - each shot has it's own particular needs and balancing them to get the best result takes all these factors into account.

[rpcrowe]

We all realize that background blur is dependent upon focal length, f/stop, and subject to camera/background to camera distance...

Using a long focal length lens such as this 300mm on a crop sensor camera, the background can be blurred in comparison to the subject even at f/8 when the subject is relatively close and the background is off in the distance...



Here's a shot at f/5.6 with the subject as well as the background much closer to the lens. I didn't do any measurements but, suspect that in this image, the ratio lens to subject and lens to background distances is somewhat similar....



Here is a shot at 106mm with a full frame camera at f/6.3 - the background is only slightly out of focus



and... here is a shot with the same distances but using 200mm at f/5.6



However, there is a new factor which recently appeared in some lenses SFT or Smooth Focus Trans (Sony jargon but, I think that other companies have similar type lenses) which changes the OOF dynamics in an image, albeit reducing the light transmission in doing do......

https://www.youtube.com/watch?v=glBCCEtHsX0

[xpatUSA]

^ Aside: I love it when you guys start to talk technical - it brings out the Music of Mathematics deep within me. It is even better when you link to papers I can read.

Bill, I seem to recall we discussed a similar subject last year, or the year before, and back then I did research the subject of blur circles as found in bokeh. Turned out that the blur circle diameter in the image plane is:

F/N*m*(D-s)/D

Where F = marked focal length mm
N = f-number
m = magnification
D = distance to background
s = focus distance from image plane to point of focus in the scene.

Nothing too fancy, just based on the standard thin lens equation ...

For my Sigma DP2 compact set to f/4 and focused at 2m: a point of light at 50m produces a blur circle of 0.072mm which is just over nine pixels on the sensor.

We need to get a virtual "Bar", I reckon the technical conversation would surely be interesting in the wee hours, post a few drams.

DPR has just such a Bar where one can read some pretty outrageous stuff:

https://www.dpreview.com/forums/1061
.

[billtils]

To be frank, although I expect that two stops down, nearly all of my lenses will be sharper than when wide open - I wouldn't know what an Aperture/Sharpness curve looked like for any of my lenses: I tested most of them in the field and then bought the ones which suited me to make photos, not to use as a lab experiment.
WW

I became interested in Aperture -v- Sharpness curves after a lot of disappointments and wasted time resulting from following the craft advice for portraits of "shoot wide open" but found that I was getting @$&* results. I eventually ran down the root cause to the performance of the lens which I had used a lot in the f/8 to f/16 range where it was the proverbial "tack sharp", but as it turned out, the performance fell off dramatically outside of that range.

I'm not a pixel peeper, I do respect your comment on buying the lenses that suit you to make photos, but I'm a scientist and like to have objective data when trouble shooting something. I also believe in prevention being better than cure (a worthy old saw that is sadly very appropriate right now) and it takes no time to run the curves using the Reikan software.

For now, keep back and keep well.

[William W]

I became interested in Aperture -v- Sharpness curves after a lot of disappointments and wasted time resulting from following the craft advice for portraits of "shoot wide open" . . etc . . . I'm not a pixel peeper, I do respect your comment on buying the lenses that suit you to make photos, but I'm a scientist and like to have objective data when trouble shooting something.

Hiya Bill,

Three comments:

> Totally understand disappointment and frustration, and any good scientist would typically default to and employ scientific methods, absolutely.

> Note that the phrase 'pixel peeping' was used twofold -
- a) for want of (i.e. the lack of) any other simple phrase that I could think of
- b) for it to be a general descriptive NOT a specific - another more wordy way of putting it would be: interrogation, analysis and application of the data testing of any and/or all of technical minutia which may be responsible for, or related to the Final Image

> I dislike eating brussel-sprouts, no matter how they're dressed up... my meaning being: perhaps I was force feed so much theory at Technical College, even though my passion (actually love) for Mathematics still remains, all I really want to do is make photos, capturing the that Moment, in that Perfect Light.

In 2017 I made an exceptional portrait of a Couple using a Polaroid Camera, one of six shots - that was a Photographic high for me: sure it could have been 1000 times technically better in the studio using >$10,000 gear, but that Moment was in front of me for one time and one time only - there is no re-shoot.

On the other hand, I have had a few tasks where I have had to recorded items for Insurance Purposes: for that forensic work, which I take very seriously, I am, I believe a very good technician, if you will, I follow exacting Laboratory and Scientific Recording procedures.

Additionally, I get an idea/question in my head now and then which becomes more than an interest - one for example back around 2008 was whether it would be better to crop (the image in Post production) or to use a Tele-extender for the shot - crikey I spent months doing tests with all my (Canon DSLR) gear and a lot of stuff I borrowed - the result is I know a good bit about that particular topic, with that particular gear: would the IN FIELD test results adhere to Mathematics related to the Camera and Lenses used? Probably. Am I interested in going further than the test results? No.

Bottom line - have fun and enjoy your Photography.

WW