[Thomasbrowphoto]

G'day,

This is more to start a conversation but could be insightful too.

Im wondering what Ideal aperture you all like to use shooting Medium format landscapes with deep depth of field but retaining image sharpness. I have found that f16 is good on most of my lenses but diffraction sets in after that. I had been told that I could stop down more on medium format than on 35mm before diffraction sets in, the question is... how much more.

I came from 35mm and usually shot at f11 for most of my Wide Angle landscapes with decent depth of field and found it was the sharpest range for my optics at the time. (16-35L)

Im feeling like f11-16 is pretty good on the 25, and 35mm etc etc, but would like to hear your thoughts.

Cheers Tom,

[Swift1]

Unless I have something close I routinely shoot f/11 with my medium format film cameras.

[mikeSF]

i also typically stay between f/11 and f/16, depending loosely on the hyperfocal distance.

[Silent Street]

Hi Tom,
This can depend on the lens and whether or not hyperfocal or conventional focusing is used. For my stock landscape lenses, 45mm f4 and 75mm f2.8AL, I don't move past f8 - f9.5 to f11 - f13 (f13, very rarely), and definitely not f16. As you note, beyond f16 diffraction is introduced into the image which will soften it (even on medium format lenses) — something a great many photographers have difficulty understanding, and blithely shoot the whole caboodle at f22 to f32 to get everything "sharp and crisp", dammit. I also do not move beyond f11 when using 35mm equipment, but lenses like Canon's 17-40 f4L or a conventional 20mm f2.8 will suffice at f8 because of their inherently great depth of field. So understanding the lens's depth relative to the ideal aperture and proximity of the focus point in the scene can help. Where things go enjoyably pear-shaped is when using a tilt-shift lens like Canon's TS-E 24mm — ideal for landscape, where traditional thumb-rules of aperature and depth of field taken on a a different dimension and either shallow or very deep apertures are freely useable.

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Last edited by Silent Street; 09-02-2014 at 07:29 PM.

[rrstuff]

This is how I think of it:

Theoretically, assuming perfect optics, the lower the f-stop the better. In practice you have a sweet-spot - stopping down improves sharpness because of lens imperfections, but diffraction counters the positive effects of stopping down. The former will depend on the lens.

As a rule of thumb, the resolution, as defined by a point-spread function would be proportional to wavelength*f-number*constant.
The constant will depend on numerical aperture, which is similar to f-stop, but accounts for medium (like air). I learned that for microscopes, but it should hold for cameras too - assume the constant to be ca. 2.5 for diameter of a PSF (or 1.25 for a radius). This is the same regardless of the sensor size.

However, since you have a bigger sensor, you can get away with a bigger circle of confusion for enlargements, so you can increase your f-stop to match that desired circle of confusion.
If you have twice as large sensor (MFT vs full frame), then you can stop down twice as much on the bigger sensor (F8 vs F16).

radius of a point spread function = 1.25*f-number*wavelength.

Here are some examples:
MFT: Olympus M.Zuiko Digital 25 mm f/1.8 review - Image resolution - Lenstip.com
Full frame: Canon EF 50 mm f/1.4 USM review - Image resolution - Lenstip.com

MFT reaches max resolution at F2.8-4.0; FF at 5.6.

[Royce Howland]

I personally stay in the range of f/8 to f/11 on my 645D and 645Z with pretty well all lenses, if I'm shooting for detail. If I'm shooting something so blurred that diffraction is a total non-issue anyway, then I'll freely stop down however much I need to control shutter speed. When shooting for detail, I can see the softening effects of diffraction by f/16 and certainly more so beyond that. It seems counter-intuitive in some ways, but if the scene is static enough, I prefer to shoot multiple frames at say f/10 and then focus stack in software, rather than stop down even to f/16. The improved results are worth the extra effort to me.

If the scene isn't static then focus stacking & blending frames may not be a choice. At that point I have to decided on what trade-off to take.

Diffraction limitation is influenced by a few different things to some extent, but purely speaking it is dominated by lens f # regardless of the format of the camera. With medium format cameras you typically have to enlarge an image less for a given print size, than is the case for 35mm or smaller format cameras. This is where the "wisdom" comes from stating that you can stop down more on medium format before diffraction sets in. Technically that's not true; you just can't see the diffraction as readily as on a smaller format image, if both are printed to the same size, because the smaller format image is enlarged more. Of course pixel pitch on a digital sensor plays into this, by determining at what point the optical effect of diffraction that is going on becomes actually resolvable on the sensor.

You can play around with some of this using the simple diffraction limitation calculator at the Cambridge In Color web site; scroll to the bottom of the page.
Diffraction Limited Photography: Pixel Size, Aperture and Airy Disks

[Thomasbrowphoto]

Thanks for replying, Its interesting to hear what others deem acceptable. I do understand that the scene and hyper-focal distance also changes things. But as a general rule it seems around the f11-13 mark sits pretty well for Landscapes.

[Ryan Tischer]

I like to shoot from f/11-16, depending on the situation. If the scene warrants, I will shoot at the sharpest aperture and then focus blend to retain maximum DOF and sharpness. Some scenes, for example, with moving flowers, make this quite difficult, while with others it isn't an issue.


I've dropping in all the layers, selecting them, and using the Edit-->Auto Align Layers followed by Auto Blend Layers-->focus stacking option gives good results and takes less time than doing it manually.

[mikeSF]

Thanks for replying, Its interesting to hear what others deem acceptable. I do understand that the scene and hyper-focal distance also changes things. But as a general rule it seems around the f11-13 mark sits pretty well for Landscapes.

Minimizing diffraction at the expense of depth of field is one of many trade-offs in photography. Being able to manage both for the specific image is the key. Here is a wide angle shot with lots of foreground.


645D & D FA25, 30 sec @f/13
looks better on flickr here: https://www.flickr.com/photos/mikeoria/13282759345/in/photostream/lightbox/


The distant pointed rock is an important part of the composition, but i chose to shift my in focus area forward, at f/13 losing infinity focus as well as sharpness on the closest rocks. The mid-ground sharpness is good which was most important for the image.
I am not opposed to focus bracketing if needed, but in this case shooting 2-exposure brackets at 30sec with the light rapidly fading and some unpredictable large waves soaking the scene, I opted to capture everything in one take.

[desertscape]

With my 67, there is no way I could ever shoot at f/11 at infinity (well maybe a few exceptions) as a means to always have the perfectly sharp image. Landscape work demands using the lenses at small stops at times to be able to express your vision of the scene. I have shot quite a few landscapes at f/32, knowing that there would be some loss due to diffraction. However, when considering a scene at f/11 and having it look bad due to having to back up away from an important foreground, I would sacrifice the sharpness slightly to get what I wanted at a smaller stop. With my 4x5, f/45 is common but I prefer f/32 when possible. The 67 has a 55 X 70mm film size and does not have to be enlarged as much as the 33 X 44mm sensor on the D and Z. So diffraction is more of an issue with the D/Z because of enlargement differential. How large you are going to enlarge the image is key to the stops you use. I will use my 90-180 zoom on my 67 at f/45 if I know I will not be making large prints. For macro work I use f/32 and f/45 a lot.

Tom, try a few shots at small stops to see if you like the results. We can talk about diffraction but you need to decide for yourself.

[Pål Jensen]

645; F:16 and be there
35mm; F:8 and be there
APS: F:5.6 and be there

[dtmateojr]

G'day,



This is more to start a conversation but could be insightful too.



Im wondering what Ideal aperture you all like to use shooting Medium format landscapes with deep depth of field but retaining image sharpness. I have found that f16 is good on most of my lenses but diffraction sets in after that. I had been told that I could stop down more on medium format than on 35mm before diffraction sets in, the question is... how much more.



I came from 35mm and usually shot at f11 for most of my Wide Angle landscapes with decent depth of field and found it was the sharpest range for my optics at the time. (16-35L)



Im feeling like f11-16 is pretty good on the 25, and 35mm etc etc, but would like to hear your thoughts.



Cheers Tom,

It depends on how big is your MF sensor and it's resolutioon. The guide that I use is that for 35mm, max theoretical resolution at f/11 is approximately 15Mp. Going up or down in f-stop or sensor size, you just double or half the max res. For example on a APS-C with 1.5x crop factor, 15Mp max is hit at f/8. So if you have a MF with 1.5 the area as 35mm then f/16 should give you 15Mp max. The implication is that if your MF is 40Mp and you are shooting at f/16 then you are not really resolving more data than a comparable sensor that only hhas 15Mp. Diffraction is the ultimate resolution equalizer.

[tuco]

With my 67, ... I have shot quite a few landscapes at f/32, knowing that there would be some loss due to diffraction.

Your 67 is in a different medium format league in terms of getting DOF with lenses than these guys with their 645D/Z, no? I mean, their "normal" lens is, what, a 55mm? And they have a 25mm! Getting deep DOF with a 25, 35 and 55mm at f11-f16 is not the same as a 45, 75 and 105mm.

[desertscape]

I think it is pretty much understood by medium format shooters that there is a difference in DOF between a 67 and a 645D/Z, given the lenses used. The benefit of a 645D/Z is that one can use a wide lens like a 35mm at f/8 while I need to use my 55mm (6x7) at f/13 to have similar DOF. Both lenses have similar angles of view. The 645D/Z has the diffraction edge over the bigger format but the bigger format has an edge in not having to enlarged as much.

[jwatts]

Shooting a P67, Hyper-focal method. I tend to hover around f/16. I try to keep it under f/16.5, and I find f/11.5 to be the sweet spot.