Aug 2009
Diffraction is the problem
18/08/09 10:11 Filed in: Education
DIFFRACTION IS THE PROBLEM
by
David Magahy
At what point do you get the sharpest possible image from the kit you currently own or are contemplating purchasing in the foreseeable future? Is more pixels the answer? Or is it a more expensive lens?
I have been following a debate on these matters on the Luminous Landscape website for some weeks. Originally Ray Maxwell wrote an essay entitled “Why Moore’s Law does not apply to Digital Photography”
In this essay he postulates that we may be soon reaching the limit of pixel growth within the confines of the 35mm format. He suggests that 100 megapixels is not only unlikely but unnecessary anyway.
Diffraction caused by the glass in the lens appears to be a major issue, and grows as a problem as the megapixels increase. As owners of the new 20 Megapixel plus cameras may be finding, there are already signs of things being slightly different than before.
I should add straight away that there are a couple of follow on essays rebutting the findings of Maxwell and they seem to become ever more complex in their explanations, especially of the Physics involved.
What I am getting from these articles is that as the megapixels rise, then the lens sweet spot falls. In other words, conventional wisdom stated that a correctly focussed image around an aperture of f11 will give you the sharpest possible result for your landscapes, with maximum detail in the fore, middle and background at the hyperfocal distance of your scene. Now, if I am understanding these essays correctly, it would appear that my Canon 5D Mk II for example, will give me a sharper image at around f8 than at f11, and that as we move to 50 Megapixel that might drop to f5.6 and 100 Megapixel might be f4.
It appears that technically it is possible to make 100 Megapixel sensors sometime in the future, but to cure the diffraction issues may prove impossible, thereby negating the advantages of a denser sensor.
If you want to really get into the arguments, then follow on from Ray Maxwells initial link above to the rebuttals
by
David Magahy
At what point do you get the sharpest possible image from the kit you currently own or are contemplating purchasing in the foreseeable future? Is more pixels the answer? Or is it a more expensive lens?
I have been following a debate on these matters on the Luminous Landscape website for some weeks. Originally Ray Maxwell wrote an essay entitled “Why Moore’s Law does not apply to Digital Photography”
In this essay he postulates that we may be soon reaching the limit of pixel growth within the confines of the 35mm format. He suggests that 100 megapixels is not only unlikely but unnecessary anyway.
Diffraction caused by the glass in the lens appears to be a major issue, and grows as a problem as the megapixels increase. As owners of the new 20 Megapixel plus cameras may be finding, there are already signs of things being slightly different than before.
I should add straight away that there are a couple of follow on essays rebutting the findings of Maxwell and they seem to become ever more complex in their explanations, especially of the Physics involved.
What I am getting from these articles is that as the megapixels rise, then the lens sweet spot falls. In other words, conventional wisdom stated that a correctly focussed image around an aperture of f11 will give you the sharpest possible result for your landscapes, with maximum detail in the fore, middle and background at the hyperfocal distance of your scene. Now, if I am understanding these essays correctly, it would appear that my Canon 5D Mk II for example, will give me a sharper image at around f8 than at f11, and that as we move to 50 Megapixel that might drop to f5.6 and 100 Megapixel might be f4.
It appears that technically it is possible to make 100 Megapixel sensors sometime in the future, but to cure the diffraction issues may prove impossible, thereby negating the advantages of a denser sensor.
If you want to really get into the arguments, then follow on from Ray Maxwells initial link above to the rebuttals
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Aug Minutes
18/08/09 10:06 Filed in: Committee
SUMMARY OF COMMITTEE MEETING MINUTES - AUGUST 2009
While Vi is away I am sitting in for her as Acting Secretary so here is the news.
New Members: On Monday Night at the Management Committee Meeting membership applications were ratified for Peter and Glynis Diamond and Stephen McKillop-Davies. Welcome to GCPS.l
I gather that the “Hunt and Shoot” and BBQ at Cascade Gardens at the end of July was well attended and that it was a good day. Now a few more people need to let Jeff have their photos so that he can pick a winner.
Also I was told that the Practical Night on Studio Portrait Lighting by David Magahy was also well attended with plenty of interest. I gather that Jeff and David are contemplating a workshop to explore these techniques further. I hope that you all found our lovely model Yurika a delight to work with. Yurika was one of the models that we had for our outdoor photo shoots when we ran the PSQ Annual Convention in 2006 at Bond Uni.
Selection of our entry for the 2009 Interclub Projected Images Competition has been completed. As always it was a difficult task trying to balance out choosing strong entries against sharing the opportunities to be selected around as much as we could. Seven Categories with just 3 entries in each.
Entries were chosen from 12 members. Hopefully we will be able to show the final selection at one of our upcoming meetings. The actual competition is on Saturday 29th August from 9:30am in the Barry Jones Auditorium, Ipswich Library Complex, cnr South and East Streets, Ipswich. Map Reference 2009 UBD Map 213 Ref: E16 $3 entry.
Unfortunately this is the same Saturday as the Gold Coast Show but, if you are not involved in the GCS on the Saturday and are thinking of going then let me know as we have been asked to advise the organisers for their seating and catering arrangements.
A few congratulations are in order this month:
Kathy Scallan is moving back to Advanced (A) Grade after her phenomenal run of awards in Intermediate (AB) Grade this year. Also, Patricia Mita and Maryanne Souter have both received the necessary 8 awards to qualify to move from Beginners (B) Grade to Intermediate (AB) Grade. Several other members are also getting close to the magical 8 awards..
The PSQ AGM - Open Meeting is on Sunday 9 August at 10am in the Chermside Library, Hamilton Street. Nomination forms are available from me.
August Competition Night (13tg Aug) (Open Subject, Impact Judging of prints). The judge is Barry Mason from Lennox Head, an FCC (NSW) Judge. Remember that your prints can be any size. The digital entries will be pre-judged as usual. Also bring in your entries for the September competition.
August Practical Night (27th Aug) will centre around a presentation by Doug and Jean Moulin, highly respected photographers from Aukland, NZ. If time permits Jeff will be talking about the wonderful things that you can do with the Liquify Tool in Photoshop.
August Outing – Sunday 30th Aug will be the Gold Coast Show.
Gold Coast Show. I am still looking for a few more volunteers for the GCPS Roster in the Visual Arts Pavillion. Mainly on Friday afternoon (28th Aug, 1p – 5p) and on the afternoon of Sunday 23rd Aug – the “Bring-In” day – from say 12:00 to 3:30.pm That will be when we hang the entries.
That’s about it for this month. Anything else will be covered by email as the need arises.
KEN SPARROW
Acting Sec
While Vi is away I am sitting in for her as Acting Secretary so here is the news.
New Members: On Monday Night at the Management Committee Meeting membership applications were ratified for Peter and Glynis Diamond and Stephen McKillop-Davies. Welcome to GCPS.l
I gather that the “Hunt and Shoot” and BBQ at Cascade Gardens at the end of July was well attended and that it was a good day. Now a few more people need to let Jeff have their photos so that he can pick a winner.
Also I was told that the Practical Night on Studio Portrait Lighting by David Magahy was also well attended with plenty of interest. I gather that Jeff and David are contemplating a workshop to explore these techniques further. I hope that you all found our lovely model Yurika a delight to work with. Yurika was one of the models that we had for our outdoor photo shoots when we ran the PSQ Annual Convention in 2006 at Bond Uni.
Selection of our entry for the 2009 Interclub Projected Images Competition has been completed. As always it was a difficult task trying to balance out choosing strong entries against sharing the opportunities to be selected around as much as we could. Seven Categories with just 3 entries in each.
Entries were chosen from 12 members. Hopefully we will be able to show the final selection at one of our upcoming meetings. The actual competition is on Saturday 29th August from 9:30am in the Barry Jones Auditorium, Ipswich Library Complex, cnr South and East Streets, Ipswich. Map Reference 2009 UBD Map 213 Ref: E16 $3 entry.
Unfortunately this is the same Saturday as the Gold Coast Show but, if you are not involved in the GCS on the Saturday and are thinking of going then let me know as we have been asked to advise the organisers for their seating and catering arrangements.
A few congratulations are in order this month:
Kathy Scallan is moving back to Advanced (A) Grade after her phenomenal run of awards in Intermediate (AB) Grade this year. Also, Patricia Mita and Maryanne Souter have both received the necessary 8 awards to qualify to move from Beginners (B) Grade to Intermediate (AB) Grade. Several other members are also getting close to the magical 8 awards..
The PSQ AGM - Open Meeting is on Sunday 9 August at 10am in the Chermside Library, Hamilton Street. Nomination forms are available from me.
August Competition Night (13tg Aug) (Open Subject, Impact Judging of prints). The judge is Barry Mason from Lennox Head, an FCC (NSW) Judge. Remember that your prints can be any size. The digital entries will be pre-judged as usual. Also bring in your entries for the September competition.
August Practical Night (27th Aug) will centre around a presentation by Doug and Jean Moulin, highly respected photographers from Aukland, NZ. If time permits Jeff will be talking about the wonderful things that you can do with the Liquify Tool in Photoshop.
August Outing – Sunday 30th Aug will be the Gold Coast Show.
Gold Coast Show. I am still looking for a few more volunteers for the GCPS Roster in the Visual Arts Pavillion. Mainly on Friday afternoon (28th Aug, 1p – 5p) and on the afternoon of Sunday 23rd Aug – the “Bring-In” day – from say 12:00 to 3:30.pm That will be when we hang the entries.
That’s about it for this month. Anything else will be covered by email as the need arises.
KEN SPARROW
Acting Sec