Can lenses get much better??

CheshireCat wrote in post #18219792
Fair enough, I was probably too harsh to make my point.
Let's just say that if all the important elements are at infinity, there is no need to stop down for DOF.

I agree with you. If all of the important elements are at infinity, there is no need to either stop down, or focus anywhere else. It will yield a relatively boring photograph, but hey, shoot what you want. Implying that folks who produce good landscape photos do it this way is simply wrong.

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CheshireCat wrote in post #18219792
Fair enough, I was probably too harsh to make my point.
Let's just say that if all the important elements are at infinity, there is no need to stop down for DOF.

Right, but the typical "formula" that many landscape photographers use, or a "rule" that many follow, is to have elements of interest in the near foreground and a vast scenic vista in the background. This is common practice, and pretty much the norm in landscape composition.

In fact, this "rule" is so entrenched in some photographer's thinking that sometimes when a photo is posted on a landscape photography forum, it will receive comments like, "nice, but.....you forgot the foreground", or, "where is your foreground?"

If you want to see more about this, just go here and see rule #2:
http://www.photography​vox.com …on-landscape-photography/

Of course, one doesn't always have to have foreground elements in order to create a great landscape image. But it is common practice, and to say that most landscape photographers don't stop down to gain depth of field seems to show a lack of knowledge about the way that most landscape photographers go about composing their images.

If you look at the online galleries of the world's most successful landscape photographers, you will see that many of their images contain near foreground elements along with vast distant vistas......with everything in focus, or very nearly in perfect focus.

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That's with ultra wide angle lenses, longer lenses don't work that way and do rely on infinity focus often.

For close foreground shots, expect to do focus stacking, even with UWA lenses

CheshireCat wrote in post #18219822
About diffraction: of course it is a physical thing and there is no such thing as a diffraction-free lens, but in optics it is often useful to talk about a "perfect lens" when discussing other matter not involving diffraction.

About the HFD scales displayed by our lenses, they are simply useless for digital photography.
The right equation for HFD is the one that keeps the circle of confusion smaller than the sensor pixel size. A HFD scale would then vary depending on the sensor density.

Your examples about the viewer with 20/20 vision will be even more extreme if the viewer is pixel-peeping at 1:1 on a computer display. That is what I am talking about when I say "critically sharp": pixel level sharpness.
And my next point is that if you want pixel-level sharpness at infinity using HFD, you may need to stop beyond diffraction (and at that point, diffraction becomes painfully real).

When I have the time, I'll shoot some example with the 24/1.4 to show you guys how ridiculous HFD scales are nowadays.

The DOF scales on our lenses were USELESS 50 years ago even with film simply, because they were so optimistic!!!
For example, a 35mm lens from the 1960s shows DOF at f/5.6 from about 12' to Infinity when focused at about 20', similar to a current DOF program (using 'manufacturer standard') calculated DOF zone of 11' - 3533'
I used to routinely use a DOF scale mark one f/stop larger than shooting aperture, simply for a bit more realism in the assessment of the DOF zone depth, but even that was still optimistic...
Assuming f/16 shooting aperture...

• at f/16, 'manufacturer standard' program says Hyperfocal at 7.8' with DOF zone of 4' - 372'; DOF scale on lens says DOF 4'- Infinity
  
• at f/11 'manufacturer standard' program says Hyperfocal at 11' with DOF zone of 4.7' - 24'; DOF scale on lens says DOF 6'- Infinity
  
• at f/5.6 'manufacturer standard' program says Hyperfocal at 11' with DOF zone of 4.7' - 24'; DOF scale on lens says DOF 12'- Infinity
  

Charlie wrote in post #18219861
That's with ultra wide angle lenses, longer lenses don't work that way and do rely on infinity focus often.

For close foreground shots, expect to do focus stacking, even with UWA lenses

But it was the norm even back in the film days, without any focus stacking being done........hence, the existence of Group f.64, the f/22 Club, etc.

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Took me a while to find it, but I finally found a copy of the 1990 article on Merklinger's Ins and Outs of Focus that described the "focus on infinity and stop down for defining details resolved" idea that people are mentioning:

http://www.trenholm.or​g/hmmerk/TIAOOFe.pdf

If you haven't read it before, I find it interesting. If the discussion is uninterestly technical to you, then at least glance at his example photos of his sister on pg 23 and pg 30 to see the difference in hyperfocal and infinity focusing at the same aperture setting.

Scanning it quickly I don't see any mention of diffraction limits, I think this may be a strong limitation to his idea. I experimented with this (with film) when I first stumbled upon it a couple of decades ago, and I think it has something to offer, mainly in the idea that Depth of Field and Circle of Confusion are contrived and don't adequately describe how I react to images that I pixel peep. To me, when someone says "the nose and ears are in the DOF" I mentally translate that as "I focused on the eyes and the nose and ears are acceptably blurry to me". If I take a single shot now with near and far subjects that I want to render, I choose an aperture setting based on the smallest details I wish to resolve nearby, and I focus somewhere between the hyperfocal distance and infinity (sometimes I take all 3 shots and choose one, rarely the hyperfocal). Also, if you pretend that digital allows say 2 stops better COC, so that for f/16 you use f/8's hyperfocal distance [edited to fix my typo], it is sort of like choosing a compromise between the hyperfocal distance and infinity.

Anyway, because some of this discussion appeared to have people unfamiliar with this, I thought this might help to understand the (ray tracing) background.

But yeah, focus stacking is the modern way to get it all in focus.

Tom Reichner wrote in post #18219888
But it was the norm even back in the film days, without any focus stacking being done........hence, the existence of Group f.64, the f/22 Club, etc.

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I'm not quite sure my lenses can even go to f64, and often F22 isnt enough, and quite a detriment to IQ.

classic focus stack scenario attached, no amount of stopping down would have solved this. due to focus breathing, quite a mess trying to merge...... would have loved a single shot and do have several, none have the bite of a stack

I stand corrected, he covers diffraction at least partly if you read on down into chapters 6 and beyond...

Gotta be honest.

I do not understand a lot of what you guys are saying.

CheshireCat wrote in post #18219742
Diffraction has nothing to do with this.
What I am simply saying is that if you have a perfect lens (with no diffraction) with an effective aperture of 21mm focused at infinity, on a perfect sensor, it will be ablle to resolve any detail bigger than 21mm, no matter how far that detail is from the lens.
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Perfect lenses still have diffraction, its a physical law.
And without diffraction I see no reason why a lens should only resolve its entrance pupil diameter?
Without diffraction it could resolve anything, and even with diffraction it can resolve smaller details than entrance pupil in near distances. A 50mm lens at f/1.4 can resolve smaller details than 35mm size in 1 meter distance. Your theories are totaly wrong. Please try to understand optics a bit more

FTb wrote in post #18217109
The technology already exists for MUCH higher resolving lenses than those currently used on consumer cameras -- optics in commercial satellites are close to being able to resolve peoples' expressions from near earth orbits. Who know what the top secret military stuff can do? Just a matter of price, size/weight and demand.

I was told by a military contractor years ago that they have cameras that can read the writing on a pack of cigarettes from space...... Not bad resolution.

Charlie wrote in post #18219908
I'm not quite sure my lenses can even go to f64, and often F22 isnt enough, and quite a detriment to IQ.

Don't forget that negative sizes were often quite large back then compared to 35mm today.

An 8x10" contact print could tolerate quite a bit of diffraction in the negative stage and still look sharp because diffraction effects were rendered at unity, whereas with 35mm, diffraction effects are multiplied many time during enlarging.

Phoenixkh wrote in post #18220006
I was told by a military contractor years ago that they have cameras that can read the writing on a pack of cigarettes from space...... Not bad resolution.

I know that the image of my house on Google Earth has resolution enough to show my weather station and that's about 12" by 6" when viewed from the top. It's not but a few pixels but it's easily identifiable.

ZoneV wrote in post #18219992
Perfect lenses still have diffraction, its a physical law.

Perfect lenses do not exist and are an assumption to simplify the discussion.
Therefore, please stand by my own definition of a "perfect lens" as a lens that has no aberrations and no diffraction whatsoever.

ZoneV wrote in post #18219992
And without diffraction I see no reason why a lens should only resolve its entrance pupil diameter?
[...]
Your theories are totaly wrong. Please try to understand optics a bit more

The reason is that the lens is focused at infinity, like I said several times.
Sorry, but my theories are solid (I have studied) and they are also explained in Merklinger's paper cited above. Try reading it, it is very interesting !