small aperture = blurred images with A6000

[xya]

My A6000 has with all lenses in the mode "A" the same phenomenon: if you close the aperture completely, the images are blurred. I use mainly manual lenses, but with the SELP1650 it's the same. The photographs were taken with a tripod, camera shake is therefore excluded. With my A7 this does not occur. What could that be? Any ideas?

 

I contacted the Sony service, but they haven't answered yet.

[yali]

I think what you're experiencing is called Diffraction. Read about it here:

https://luminous-landscape.com/understanding-lens-diffraction/

 

a6000 vs A7: I think it's also worse with smaller sensors than with larger ones. Hence the difference between your cameras.

[xya]

thank you for your answer and the link. maybe this is it, but it should not be the case with a Sony lens, made for these cameras.

 

I put links to 2 pages with full resolution pictures that I cannot post here. the pages are not linked within my webite, so you have to start from here.

http://www.a7camera.com/a6000_voigtlaender_25.html

http://www.a7camera.com/a6000_sony_16_50.html

 

thank you for looking.

[miran]

Diffraction is a physical phenomenon and affects all lenses equally. Compare it to gravity for example: it's 9.81m/s^2 for everyone and everything on this planet, no exceptions. Same with diffraction. On crop sensor diffraction will usually start softening photos at around f/8. An acceptable compromise between sharpness and maximum dof might be f/11. In most cases f/16 should be absolutely last usable aperture. Use f/22 only if you really have a good reason. On full frame the same is true, except shift these recommendations by 1 stop towards closed apertures (f/11 is good, f/16 is ok, f/22 barely acceptable). Of course this is just a rule of thumb, in reallity it also depends on focal length, shape of aperture, etc.

[Guest all8]

Here is a good explanation, with calculator:

 

http://www.cambridgeincolour.com/tutorials/digital-camera-sensor-size.htm

 

 

 

Larger sensor sizes can use smaller apertures before the diffraction airy disk becomes larger than the circle of confusion (determined by print size and sharpness criteria). This is primarily because larger sensors do not have to be enlarged as much in order to achieve the same print size. As an example: one could theoretically use a digital sensor as large as 8x10 inches, and so its image would not need to be enlarged at all for a 8x10 inch print, whereas a 35 mm sensor would require significant enlargement.

[Golem]

Special circumstance:

 

While f/22 might be borderline OK for a

55mm lens on the 24x36mm format if

DOF is a major priority for the shot, a

55mm Micro Nikkor stops way down to

f/32, even tho the lens is intended for

critical use. But ... as you approach 1:1

the effective focal length increases due

to the extension. At 1:1 it functionally

has a 110mm FL. Thaz why it has that

f/32. Acoarst using f/32 on subjects a

feet away invites heavy diffraction.

 

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[xya]

thank you very much, folks, for your contributions. I learned a lot. As I come from mid and large format photography, diffraction wasn't a problem. So I put my A6000 lens comparison online.

 

it's here: http://www.a7camera.com/a6000_lens_comparison.htm

 

Sony service has contacted me, but wasn't very helpful (reset your camera, try the helpdesk, send it in for repair).

[yali]

Just read any pixel peeping lens review of FF or APS-C lens ever. They will tell you that at f22 diffraction destroy pretty much all the sharpness Especially the smaller sensors. If you come from mid and large format I guess that's the reason you didn't experience this before.

[Golem]

Another special circumstance:

 

F/22 [or even 32] is reeeeaaally great for

hunting down dust on your sensor before

cleaning it, and for doing dust mapping

when using firmware or software to hunt

and erase dust from the recorded image.

 

Acoarst the ultimate such tool may be no

lens at all, but just a pin-holed body cap.

 

`

[Golem]

........ As I come from mid and large format

photography, diffraction wasn't a problem. ..........

Those lenses stop down to f/64 and also suffer just

as badly from diffraction. The degree of enlargement

for the finished product was usually much less than

with small cameras, so that you didn't often see the

effects of diffraction. But when you make large prints

[for trade shows, etc] you find that "peering deeply"

into the prints did not reveal hidden detail. From a

normal viewing distance such prints APPEAR very

highly detailed, but if you "invited yourself in" to the

world they presented, that world lacked fine detail

[if it was a product shot at tiny aperture. Not ALL

large camera work was at f/45 or f/64 ! ]

 

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