Focus and aperture

[joelouw]

Hey guys

My very 1st post to this forum.
Not sure if this was ever discussed before but I have a friend that is a very good landscape photographer, still shoots film - in particular 6x17 film.

Now he recently went to digital, and being a landscape photographer maximum DoF is required most of the time.

Well here are 2 shots that was taken with a Nikon D810 with the 80-400 Nikor
The shots were taken in manual focus on a tripod. The focus was achieved and the one shot (the sharp one) was taken at f10 the out of focus one was taken at f40 and NO the focus ring was not bumped or moved between the 2 shots.
It;s this just digital or what.
We did the same test using a set of Zeiss lenses with te manual aperture rings and the came out perfect. Seems like when ever we use a lens with a electronic aperture this is an issue.

Any advice?

Joe

[mbaginy]

The phenomenon is called diffraction.  The unsharp image was stopped down far too much.

I often shoot at various f stops, then check for sharpness.  If my image stopped down to f22 (as an example) is still sharp enough, I’ll keep it but I know I’ll have to post process it differently, i.e. increase sharpness more.  Maybe also increase “clarity” in LR5, thus increasing mid tone contrast.  I fear, that your image stopped down to f40 was too extreme.

Mostly, I shy away from stopping down more than f16.  If the image requires it though, I will and then check as described above.  I also (always!) use mirror lockup and a cable release.  Another important detail I’ve found is, to wait some six to seven seconds after locking up the mirror, before releasing the shutter.

I doubt the Zeiss aperture ring had anything to do with the image being blurry.  When releasing the shutter, the aperture blades close to the set aperture - regardless of setting with aperture ring or using a dial on the camera body.  You'd only minimize the (minimal) potential for movement if stopping down the aperture while composing the shot.  I doubt that's what you did.

[joelouw]

Hi Mike

Thanks so much for your response.
OK yes maybe f40 was just to much, but that was just to illustrate but fact is it that even on f22 or f25 it's still unsharp.
So I get that it's the bending of light.

So that is then just the way it is, sadly. But now the question is:

1: Why does this not happen on film?
2: Why does this not happen when we use a Nikon mount Zeiss lens (with manual aperture) - we used multiple Nikkor lenses all with electronic aperture and multiple Zeiss lenses all with a manual aperture. We used the Zeiss because that is what we have with a manual aperture ring.
3: Does this in-fact got to do with digital or electronic apertures?

What is the technical explanation of this. Sure the principal of photography and a lens via a DSLR is the same if it's Digital or Film

Just to be clear when we did the test we only used mirror up and cable release. Also the test showed that the lenses with the manual aperture ring it did not happen.

Or do we need to glasses :-)

[joelouw]

I found this. http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Looks like the high MP dens pixels of 36MP camera are not helping us :-) and making a bit worst.
The manual aperture vs electronic aperture on the same camera still puzzels me.

Joe

[thierrylegros396]

I found this. http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Looks like the high MP dens pixels of 36MP camera are not helping us :-) and making a bit worst.
The manual aperture vs electronic aperture on the same camera still puzzels me.

Joe

Yes, you're right, we need the best lenses with these "high MP count" sensors.

Thierry

[mbaginy]

Joe, don't forget, that you are comparing a prime Zeiss lens ("prime" meaning fixed focal length) with a zoom.  While the image quality of zooms have increased dramatically in comparison to twenty years ago, I'd venture to say say that primes usually beat zooms.  A generalisation for sure but true with only a handful of exemptions.  The 80-400 zoom, while high quality, isn't one of Nikon's absolute best - the 200-400 for example is in a different league and would compare differently.  But not at f40.

By the way, diffraction is not limited to lenses of digital cameras.  It was noticed shooting film as well.  But, as Thierry mentioned, today's sensors require the very best lenses and shooting technique - proper focusing, ideal aperture, tripod, mirror lockup, etc. for best image quality.  Compromise as you deem fit.

[PhotoEcosse]

Just for your friend's peace of mind, landscape photography with the D810 should never require very small apertures. The lenses that I use most often for landscapes with my D810 are (in order of frequency of use) all f/2.8 Nikkors - 24-70mm, 70-200mm and 14-24mm.

With those lenses, I get adequate depth of field for normal landscapes at the apertures that I find give the best results on each lens, namely f/8 on the first two and f/5.6 on the uwa.

I think I can safely say that I have never had to go smaller than f/11 on any of those lenses to get ultra-sharp results with the depth of field that I need.

[Slobodan Blagojevic]

...1: Why does this not happen on film?...

It does.

Just that we never enlarged film to the same extent (100%+) as we do digital. Looking at film under a microscope wasn't a part of workflow.

[joelouw]

Just for your friend's peace of mind, landscape photography with the D810 should never require very small apertures. The lenses that I use most often for landscapes with my D810 are (in order of frequency of use) all f/2.8 Nikkors - 24-70mm, 70-200mm and 14-24mm.

With those lenses, I get adequate depth of field for normal landscapes at the apertures that I find give the best results on each lens, namely f/8 on the first two and f/5.6 on the uwa.

I think I can safely say that I have never had to go smaller than f/11 on any of those lenses to get ultra-sharp results with the depth of field that I need.

Thank you ALL for your replies - MUCH appreciated.
One thing I like to then comment on this above:
OK so the D810 for landscapes does not require small apertures, it does give some peace of mind.
One thing though - if f22 and smaller is such a problem, why are the lens manufactures then not just take those apertures away then. Since nothing is sharp on it in anyway :-) E.g. Let the lens stop on f11 then....

Joe

[spidermike]

It's called choice.
Diffraction limitation is just that - limiting, not necessarily degrading. All it means is that the start of diffraction limitation offsets any benefit of increased depth of field. Detrimental effects take another couple or more stops to kick in (with film I was always told f22 is starting to get dodgy) and some people take the view 'I don't need f16 so why take the risk' rather than 'images at f16 are less sharp than images at f11'.

I have seen a fair bit of debate as to whether diffraction problems (as opposed to just 'diffraction effects') are a real-world issue for most photographers most of the time at the sizes most people print/view them. Pixel peepers, yes - detrimental to the image less so. Having said that, f40 is a very small aperture and I am not surprised you are seeing problems in that particular case.


JeLouw posted:

I found this. http://www.cambridgeincolour.com/tutorials/diffraction-photography.htm

Looks like the high MP dens pixels of 36MP camera are not helping us :-) and making a bit worst.
The manual aperture vs electronic aperture on the same camera still puzzels me.

I can't quite get my head round why. If I took a picture with a 16MP camera and the same picture with a 36MP camera, and viewed them at the same size and viewed them from the same distance why would I see more diffraction blurring with the high MP camera? As far as I can tell, the margins of the blur will be the same distance.
I realise that you will be more likely to see diffraction blurring when viewing at 100% in a photo editor, but that is also because you are blowing the image up much larger on-screen. 

[John Rodriguez]

Thank you ALL for your replies - MUCH appreciated.
One thing I like to then comment on this above:
OK so the D810 for landscapes does not require small apertures, it does give some peace of mind.
One thing though - if f22 and smaller is such a problem, why are the lens manufactures then not just take those apertures away then. Since nothing is sharp on it in anyway :-) E.g. Let the lens stop on f11 then....

Joe

What aperture you need is dictated by your composition - some compositions definitely need f22 on 35mm.  Diffraction isn't nearly the bugaboo as many people make it out to be unless you're looking at 100% images on a screen.  The difference between 35mm f11 and f22 in a 200 ppi print at reasonable viewing distances is small.

A few factors to consider with your stated use case:

- Your friend was probably using a prime lens with his 6x17, and those zeiss lenses are definitely primes.  An 80-400 isn't going to be nearly as sharp.  Also, some lenses have a nasty habit of changing focus when you stop down - you're probably running into that.
- f40 is pretty extreme.  

This isn't a digital vs film problem - you'd have the exact same issue if you used that lens like that with film, it would just be harder to spot unless you scanned it really well.