Sweet Spot for Landscape Photography (Page 10): Thanks!

IDguy Loc: Idaho

gordone wrote:

Quality of Focus

Thanks!

IDguy Loc: Idaho

I found this page interesting: https://www.cambridgeincolour.com/tutorials/diffraction-photography.htm#calculator?utm_source=newsletter&utm_medium=email&utm_campaign=fup4

(Edit: I now see it was posted on p. 3. Missed it then.)

The thing bothering me up to this point is that the topic is about landscape photography, which generally means maximizing the DOF, and much of the discussion on diffraction does not address DOF. Enjoy playing with the calculator.

My conclusion: f22 for full frame and f16 for APS-C are OK. But yes, if you want to maximize sharpness at the focus then more like f16 and f11.

IDguy Loc: Idaho

Jsykes wrote:

Having problems with the (often published) recommendation(s) of how to "squeeze the maximum levels of image sharpness out of your lens by simply stopping your lens aperture down 2.5 to 3-stops from the lens's maximum aperture" i.e. for a lens that has a maximum aperture of f/3.5, the sweet spot of your lens resides somewhere between f/8 and f/11.

Using my 18-55mm kit lens and its' max aperture of f/3.5, two F stops would be f/4.5 and three F stops f/5.6.

Comments?

Yes. This is an example of not addressing DOF. With landscape photography we aren’t generally (exceptions like fog noted by Linda) after best sharpness only at the focus point but rather acceptable focus over a large DOF.

IDguy Loc: Idaho

Might find this interesting, too:

https://www.adorama.com/alc/0014123/article/Join-the-f22-Club-And-Transform-Your-Landscape-Photography

and this:

https://youtu.be/qW7NcMqMoVY

or even this:

https://www.exposureguide.com/landscape-photography-tips/

TriX Loc: Raleigh, NC

IDguy wrote:

Yes. This is an example of not addressing DOF. With landscape photography we aren’t generally (exceptions like fog noted by Linda) after best sharpness only at the focus point but rather acceptable focus over a large DOF.

Yep, unless everything is perfectly stationary so you can focus stack, then the photographer must make a choice/compromise between DOF and diffraction/sharpness - a different issue than just max sharpness.

Dick B

Jsykes wrote:

Having problems with the (often published) recommendation(s) of how to "squeeze the maximum levels of image sharpness out of your lens by simply stopping your lens aperture down 2.5 to 3-stops from the lens's maximum aperture" i.e. for a lens that has a maximum aperture of f/3.5, the sweet spot of your lens resides somewhere between f/8 and f/11.

Using my 18-55mm kit lens and its' max aperture of f/3.5, two F stops would be f/4.5 and three F stops f/5.6.

Comments?

A stop is by definition a change in light by a factor of 2 ( or 1/2 ) since the amount of light is controlled by open area of the diaphragm, and area
=pi r squared. So 1 stop smaller than f 3.5 is 3.5 * 1.414=4.949 call it f4.9 or f5.0, 1 stop smaller than f4.9 is f7.0. Note than 2 stops is 1.414 * 1.414 =2 so a change of 2 stops is always double ( or 1/2 ) of the starting f stop number. A 1/2 stop change is numerically a factor of square root of 1.414 or 1.189.

gordone Loc: Red Deer AB Canada

IDguy wrote:

I found this page interesting: https://www.cambri... (show quote)

I did some bench testing (with Reikan Focal) at F 8 and F22 on a Canon 5DS-R camera and 3 zoom lenses to see how much degradation there is in image quality. The results are:
Canon 11-24 F4 at 11 mm - image quality degradation is 23%
Canon 16-35 F2.8 iii at 16 mm. - image quality degradation is 24%
Canon 24-70 F 2.8 ii at 24 mm. - image quality degradation is 21.2 %
The results are very consistent.

IDguy Loc: Idaho

gordone wrote:

I did some bench testing (with Reikan Focal) at F 8 and F22 on a Canon 5DS-R camera and 3 zoom lenses to see how much degradation there is in image quality. The results are:
Canon 11-24 F4 at 11 mm - image quality degradation is 23%
Canon 16-35 F2.8 iii at 16 mm. - image quality degradation is 24%
Canon 24-70 F 2.8 ii at 24 mm. - image quality degradation is 21.2 %
The results are very consistent.

Without knowing the meaning of degradation such information is useless. Plus we don't know if the data is for F8 or F22. The standard for DOF is smearing over three pixels. Is that 30%?

I have no clue what the measure means but doubt it addresses the tradeoff of DOF and lens effects such as difftraction (which is one of several).

TonyBot

IDguy wrote:

Without knowing the meaning of degradation such information is useless. Plus we don't know if the data is for F8 or F22. The standard for DOF is smearing over three pixels. Is that 30%?

I have no clue what the measure means but doubt it addresses the tradeoff of DOF and lens effects such as difftraction (which is one of several).

Well, it seems clear to me that Gordon checked in "real-life" testing on his equipment and in his way what happened with him. I think its good info for me - it certainly was for him.

Blurryeyed Loc: NC Mountains.

Jsykes wrote:

Thanks

I am seeing f/3.5>>f/4.0>>f/4.5>>f/5.6>>f/6.7>>f8.0>>f/9.5>>f11

You are counting 1/2 stops, because you started at 3.5 you probably should call 9.5 your third stop from wide open. When you talk about a lens' sweet spot it is hard for me to understand what you are talking about, typically for landscape photography you want a small aperture f/16 or smaller to get everything in front of the camera into usable focus. But when you talk about a lens' sweet spot, I think that you are talking about maximum sharpness and CA performance across the frame, and that would typically occur 2 to three stops smaller than wide open.

IDguy Loc: Idaho

TonyBot wrote:

Well, it seems clear to me that Gordon checked in "real-life" testing on his equipment and in his way what happened with him. I think its good info for me - it certainly was for him.

What does it tell you?

TriX Loc: Raleigh, NC

IDguy wrote:

What does it tell you?

If I read his post correctly, it tells me that there is a noticeable (not unexpected) degradation in sharpness (>20%) between f8 and f22 on all the lenses he tested, validating the concept by actual testing that there is measurable diffraction at f22 on a high res FF body with high quality zoom lenses.

IDguy Loc: Idaho

TriX wrote:

If I read his post correctly, it tells me that there is a noticeable (not unexpected) degradation in sharpness (>20%) between f8 and f22 on all the lenses he tested, validating the concept by actual testing that there is measurable diffraction at f22 on a high res FF body with high quality zoom lenses.

Yes, but that doesn’t address the trade off with DOF. The DOF is much wider at f22. Sure, there will be some degradation at the focus distance point but the rest of the Landscape image will appear much sharper to the human eye.

So I don’t get what the numbers mean.

selmslie Loc: Fernandina Beach, FL, USA

IDguy wrote:

Yes, but that doesn’t address the trade off with DOF. The DOF is much wider at f22. Sure, there will be some degradation at the focus distance point but the rest of the Landscape image will appear much sharper to the human eye.

So I don’t get what the numbers mean.

If most of the landscape is at infinity, you only get deterioration from diffraction. The extra DOF only helps if there is a substantial part of the scene near the camera.

If you have a lot of the scene at infinity but some interesting foreground, you are better off staying below the diffraction limit and stacking an image focused at infinity with one or more focused closer to the camera.

TriX Loc: Raleigh, NC

IDguy wrote:

Yes, but that doesn’t address the trade off with DOF. The DOF is much wider at f22. Sure, there will be some degradation at the focus distance point but the rest of the Landscape image will appear much sharper to the human eye.

So I don’t get what the numbers mean.

We agree. As I said before, for landscape photographers where DOF is critical, it’s a trade-off between DOF and degradation in sharpness from difraction. My take away from the test (which I already knew, but has been contested here) is that diffraction is real and significant at f22 (and also at f16) for FF (and worse as the sensor becomes smaller). This type of data, combined with a good DOF calculator, such as DOFMaster is a tool, and gives you the data you need to make the best compromise possible for your particular shot based on actual numbers rather than guessing.