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Tutorials, Informative & Classic threads A new e-Group area for all the wonderful tutorials and helpful threads put on here by our members. Tutorials on using software, camera hardware - and feel free to request a tutorial if you need assistance!

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  #16  
Old 12th July 2017
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Re: Diffraction confusion!

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Originally Posted by David M View Post
You get diffraction with film, it's just that there was no internet for the "experts" and trolls to tell people they were shooting film wrong.
Read the post #14 from Paul (PDK42) below yours .

It kind of sums up what I said. Physics is Physics in the end
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  #17  
Old 12th July 2017
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Re: Diffraction confusion!

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Originally Posted by pdk42 View Post
- The apparent loss of sharpness will increase as the magnification of the original image to final image increases. This means that smaller sensors will be more impacted by diffraction effects.

- As pixel pitch decreases (e.g. by packing more pixels into the same area) then the impact of diffraction will become more evident simply because the higher resolution of the sensor has the potential to show more detail.
I don't think the pixel pitch matters unless you're viewing at 100%... the viewed image size and viewer distance is what determines the perceived sharpness. As someone said earlier the DoF estimates generally assume a standard print size/viewing distance and diffraction is essentially the same process.
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  #18  
Old 12th July 2017
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Re: Diffraction confusion!

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Originally Posted by David M View Post
You get diffraction with film, it's just that there was no internet for the "experts" and trolls to tell people they were shooting film wrong.
Even without those 'experts & trolls' diffraction was very noticeable in many pinhole photographs even when shot on film.

Yes diffraction affects the sharpness in some of my digital shots, but normally not noticeably unless going to very small apertures. I don't think I've ever had a 'troll' tell me I was shooting wrong due to diffraction.

Diffraction limits may well have been mentioned when I first tried digiscoping - my scope starting as a 1000mm f/16 and zooming in to a 4000mm f/64 but not gaining detail in doing so. I certainly wouldn't consider anyone just giving an explanation for an encountered issue to be a troll. At the time I was using a 6MP APSC DSLR which would I believe be diffraction limited at ~f/16 just as I was seeing.

But perhaps one persons constructive criticism or helpful explanation is another persons trolling! Many of us are keen to have advice on how to improve, and if it comes from an armchair expert who doesn't know the full story it can usually be ignored without too much fuss.
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  #19  
Old 12th July 2017
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Re: Diffraction confusion!

Excellent discussion guys, just what I was hoping for.
Oh and that's a stunning shot Michael. If I could get images like that regularly I certainly wouldn't worry about diffraction. Not that I was worried about it, just like to get things that don't quite sit right in my mind explained properly.
I'm pretty much in agreement with you all and to be honest I was applying the same aperture philosophy as Paul generally until I went on a photo workshop about 18 months ago. Then the tutor asked me what was the diffraction limit for my camera. When I said I didn't know he said ok we'll work it out then. He proceeded to set the camera up on a tripod and focus on some small type on a document probably 5 ish feet away (memory is a bit hazy about the actual distance). Anyway he then proceeded to take shots at gradually decreasing aperture values. We then flicked through the magnified images on the LCD screen to see where the letters started to get noticeably softer. This turned out to be around f12 to f14. Hence we took f11 as a pretty safe practical limit. It's worked out pretty well as a limit since although I do still often drop back to larger apertures as I used to. I was surprised the diffraction calculations were giving so much smaller f numbers than we worked out practically. I'm happy diffraction softening effects are likely to be subtle and real world shots may well not show much effect. I printed off some of the f11 shots at 16x12 recently and they looked fine to me so overall no worries.
The only oddity left I guess is why the two diffraction calculators give different results? I think I can live with not knowing the answer though so will sleep fine tonight. Thanks again for all the responses.
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  #20  
Old 13th July 2017
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Re: Diffraction confusion!

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Originally Posted by Michael Sewell View Post
I have to say, way back in the day of film, I used the aperture most conducive to the image I wanted to create.

A philosophy I still pursue today.
Absolutely Michael!
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  #21  
Old 3rd October 2017
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Re: Diffraction confusion!

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Originally Posted by pdk42 View Post
....
Personally, I consider f8 to be my limit in u43. I might push it to f11 if I need the extra DOF or maybe to pull the shutter speed down.
I've been trying as narrrow as f/14 in macro work with moving subjects, as I lose far more shots due to DoF limitations than to diffraction.

Quick question. what does diffraction actually look like? How can I look at an image and say that it's suffering diffraction? Is it just an overall lack of sharpness? (If so it's hard to be sure whether diffraction or soething else caused it)
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  #22  
Old 3rd October 2017
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Re: Diffraction confusion!

IF you go to this site it gives an example of what diffraction looks like towards the bottom of the page.

http://www.cambridgeincolour.com/tut...hotography.htm

Basically its loss of fine detail.
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  #23  
Old 3rd October 2017
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Re: Diffraction confusion!

I did some testing of Diffraction Softening some time ago:

http://e-group.uk.net/forum/showpost...08&postcount=1

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  #24  
Old 3rd October 2017
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Re: Diffraction confusion!

In recent months I have tried to avoid small apertures (say f11 and smaller) as this diffraction thing has been in the back of my mind. It has impacted on my ability to get the maximum DoF in close-up shots, which thinking about it is plain silly. I am going to use all the apertures that Oly has given us from now on and am putting two fingers up to Mr Diffraction!
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  #25  
Old 3rd October 2017
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Re: Diffraction confusion!

Quote:
Originally Posted by benvendetta View Post
In recent months I have tried to avoid small apertures (say f11 and smaller) as this diffraction thing has been in the back of my mind. It has impacted on my ability to get the maximum DoF in close-up shots, which thinking about it is plain silly. I am going to use all the apertures that Oly has given us from now on and am putting two fingers up to Mr Diffraction!
Ah, but those photons will know in advance of you closing the aperture blades and bend with the wind.
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  #26  
Old 6th October 2017
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Re: Diffraction confusion!

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Originally Posted by Michael Sewell View Post


E-M1 mkII 1/250th sec ISO64 12-40mm f16
Michael, a stunning image. Which breaks all the rules, thereby showing how silly rules can be:

- too much defraction
- glare
- purple blobs
- Backlit by the sun, which bleeds all over

Wish I could produce such technically deficient images all the time. Or even some of the time.
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  #27  
Old 6th October 2017
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Re: Diffraction confusion!

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Originally Posted by Bassman51 View Post
Michael, a stunning image. Which breaks all the rules, thereby showing how silly rules can be:

- too much defraction
- glare
- purple blobs
- Backlit by the sun, which bleeds all over

Wish I could produce such technically deficient images all the time. Or even some of the time.
I think she's falling for him
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