Education
Diffraction is the problem
18/08/09 10:11
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
|
Auto Focus Woes
14/05/09 09:49
AUTO FOCUS WOES
Do you have a Canon 50D, 5DMkII, 1D/Ds MkIII, Nikon D300, D700, D3, D3x, Sony A900 or Pentax K20. If you do, then this article will be of most interest to you. If not read on as there is a link to an article about Focus-Recompose-Shoot that we can all learn from if you use that technique with Auto-Focus.
If you have one of the new generation cameras listed, you have a feature called MicroAdjustment (or something of the same meaning depending on manufacturer)
This takes into account error tolerances in lens/sensor combinations, sometimes acceptable on their own but when combined could result in a back or front focussing nightmare.
If you shoot wide open with a fast lens, usually 2.8 or faster but can even be seen at f4 at longish focal lenghts, then it is critical that, for example, the eye that you think you have focussed on, should in fact turn out to be sharp in the image. If it’s not there are a couple of variables, such as camera shake, Focus-Recompose-Shoot error (check out this link) or front or back focussing errors.
There is now a commercial solution. I have purchased the Lens Align Lite product from the US (see a review here on Luminous Landscape site)
I have calibrated my 5 lenses, not one reading a zero on the scale, even the primes were out a little. The zooms required more correction but within the scale of the microadjustment available on the 5DMkII.
Result: my confidence has returned with auto-focussed results as expected.
There are a couple of good example images on this blog, and BTW, this guy’s stuff is worth bookmarking, especially his flash tutorials.
Contact me to arrange to have your lenses and camera calibrated for a small fee.
David Magahy
Do you have a Canon 50D, 5DMkII, 1D/Ds MkIII, Nikon D300, D700, D3, D3x, Sony A900 or Pentax K20. If you do, then this article will be of most interest to you. If not read on as there is a link to an article about Focus-Recompose-Shoot that we can all learn from if you use that technique with Auto-Focus.
If you have one of the new generation cameras listed, you have a feature called MicroAdjustment (or something of the same meaning depending on manufacturer)
This takes into account error tolerances in lens/sensor combinations, sometimes acceptable on their own but when combined could result in a back or front focussing nightmare.
If you shoot wide open with a fast lens, usually 2.8 or faster but can even be seen at f4 at longish focal lenghts, then it is critical that, for example, the eye that you think you have focussed on, should in fact turn out to be sharp in the image. If it’s not there are a couple of variables, such as camera shake, Focus-Recompose-Shoot error (check out this link) or front or back focussing errors.
There is now a commercial solution. I have purchased the Lens Align Lite product from the US (see a review here on Luminous Landscape site)
I have calibrated my 5 lenses, not one reading a zero on the scale, even the primes were out a little. The zooms required more correction but within the scale of the microadjustment available on the 5DMkII.
Result: my confidence has returned with auto-focussed results as expected.
There are a couple of good example images on this blog, and BTW, this guy’s stuff is worth bookmarking, especially his flash tutorials.
Contact me to arrange to have your lenses and camera calibrated for a small fee.
David Magahy
Exposure at April Prac Night
24/04/09 13:07
EXPOSURE AND HISTOGRAMS - RAW WINS!!
A big turn out nearing 50 attended the practical night for April. This must be one of the biggest prac night turn outs in years. Well done to Jeff and team for doing something right!! Lock in that formula!!
There are some links I’d like to give you from the talk.
1, First of all, the Luminous Landscape website that some already knew about but for those who don’t, click here.
2. Within the luminous landscape site was an article on Ansel Adams’s Zone System entitled A Simplified Zone System. Click here for the direct link. This article contains the table of descriptions of the various zones. Although it was written about film, most of it is still relevant in the digital age.
3. Another interesting article from the same website called Understanding Exposure. Click here to go directly to it or find it in the Understanding series of articles.
By the way, if you are inspired by what you see on this website, the club has subscribed to a number of the DVD Journals. See Alwyn Milligan, the Librarian, about borrowing a copy.
Today is RAW day. If you don’t start shooting RAW after last night’s maths exercise, then I don’t know what it will take to cause the shift.
Enjoy levels by the thousand,
David Magahy
Webmaster
P.S. I hope to expand the members gallery greatly by the end of the day with thanks to Rhonda Ramage who has kindly renamed all the images from the comps over the past 4 months.
A big turn out nearing 50 attended the practical night for April. This must be one of the biggest prac night turn outs in years. Well done to Jeff and team for doing something right!! Lock in that formula!!
There are some links I’d like to give you from the talk.
1, First of all, the Luminous Landscape website that some already knew about but for those who don’t, click here.
2. Within the luminous landscape site was an article on Ansel Adams’s Zone System entitled A Simplified Zone System. Click here for the direct link. This article contains the table of descriptions of the various zones. Although it was written about film, most of it is still relevant in the digital age.
3. Another interesting article from the same website called Understanding Exposure. Click here to go directly to it or find it in the Understanding series of articles.
By the way, if you are inspired by what you see on this website, the club has subscribed to a number of the DVD Journals. See Alwyn Milligan, the Librarian, about borrowing a copy.
Today is RAW day. If you don’t start shooting RAW after last night’s maths exercise, then I don’t know what it will take to cause the shift.
Enjoy levels by the thousand,
David Magahy
Webmaster
P.S. I hope to expand the members gallery greatly by the end of the day with thanks to Rhonda Ramage who has kindly renamed all the images from the comps over the past 4 months.
February Practical NIght
01/03/09 20:14
KNOW YOUR OWN CAMERA
Ken and Jeff introduced us to the possibilities for the night with a powerpoint presentation each on “your camera”. We split into interest groups, Sony/Minolta users, Canon and Pentax and some other make, Nickoff was it, a sorta Russian make I think.
There seemed to be lots of sharing so I thought I’d experiment with a quick movie or two using the Canon 5D Mk II’s HD Movie function. These clips were shot at 6400ISO and f4 (approximately).
Everyone had plenty to share with many recent purchases on view.
by
David Magahy
Movie maker...NOT!!
Ken and Jeff introduced us to the possibilities for the night with a powerpoint presentation each on “your camera”. We split into interest groups, Sony/Minolta users, Canon and Pentax and some other make, Nickoff was it, a sorta Russian make I think.
There seemed to be lots of sharing so I thought I’d experiment with a quick movie or two using the Canon 5D Mk II’s HD Movie function. These clips were shot at 6400ISO and f4 (approximately).
Everyone had plenty to share with many recent purchases on view.
by
David Magahy
Movie maker...NOT!!
Colour Management by DES
20/02/09 15:46
COLOUR MANAGEMENT
The planning for a presentation to GCPS members on Colour Management looks to be nearing completion.
We will be holding a special extra meeting on Thursday 5th March at KOA to hear a presentation organised by Sanjoy Banerjee, Business Development Manager for “DES”of Melbourne and Sydney. “DES”are the distributors for the ColorMunki colour calibration equipment from X-Rite (incorporating Gretag Macbeth) who also make the “Huey” (and the Eye-One Display).
Sanjoy will be bringing with him a rep from Ted’s in Brisbane (Cameron Attree, (Master of Photography) and will be giving part of the presentation. The presentation with cover both the calibration of monitors and of printer/paper/ink combinations
Our interest in the “Colormunki” comes from the fact that it is a 3-in-one device that enables the calibration of Computer Monitors, Printers and Digital Projector displays.
We purchased one last year prior to our hosting of the 2008 InterClub Competition for Digital Images and now use it to calibrate our laptop and digital projector combination for consistent display of our digital images (or at least we try - as some people are not happy with our efforts).
Sanjoy claims that with a properly calibrated system one can produce good colour prints using quite modest printing equipment.
If you are like me and use a commercial printer to make your prints it is also essential to know which colour space is required for your images (usually sRGB and not RGB if they are using the Fuji Frontier machines) and also to be aware that as the print is viewed in reflected light is will generally look darker that the transmitted light image on your computer screen.
Also, as projected images are viewed using the sRGB Colour Space, there is little point is submitting images in the RGB Colour Space (or with no colour profile at all) if you expect to see no changes from what you saw at home on your monitor.
An RGB image can look quite “muddy” sometimes when projected in the sRGB Colour Space. Also you need to be aware that many monitors cannot even display the wider range of colours encompassed in the RGB Colour Space.
Having said that, in our competitions one of the most common problems as that some images do not seem to have had the most basic of “Levels” or “Curves” adjustments. They do not exhibit a good range of tones – from black through to white – and they lack contrast. Consequently they look “flat” and/or “muddy “ when projected.
More to the point, without a calibrated display for your monitor and the use of an appropriate colour profile for your image, then it becomes a matter of luck as to whether your print or projected output actually matched what you saw on your own computer monitor.
We are not promoting the ColorMunki, nor suggesting that everyone should rush out and purchase one, but hopefully hearing the information that will be presented on the importance of Colour Management in dealing with your digital images then you will be in a better position to decide what is the best approach for you to follow.
Sanjoy is organising an “Unrestricted” licence for our ColorMunki software so that GCPS members can borrow the calibrator and install the software on their own computer and carry out a calibration of their own equipment (monitors, printer and paper combinations and projector if you have one).
Obviously it is not going to be practical for 70 members to be carrying out monthly caliubrations of monitors and printer/paper/ink combinations on a monthly basis using the one calibrator. However we plan to make it available to GCPS Members to use for a day or two at a time.
No doubt Sanjoy is hoping that some people will subsequently go out and purchase one of their units.
For more information go to ColorMunki:
http://www.colormunki.com/
Colour Management Information:
There is also a recent series of articles Introductory Articles on Colour Management on photo.net (http://photo.net/ ) by Jay Kinghorn on Colour Management in which the X-Rite Eye-One Display and ColorMunki are both discussed.
Part 1 – Colour Management Overview
http://photo.net/learn/digital-photography-workflow/color-management/
Part 2 – Monitor Profiling
http://photo.net/learn/digital-photography-workflow/color-management/monitor-profiling/
Part 3 – Colour Settings
http://photo.net/learn/digital-photography-workflow/color-management/configure-color-settings/
Part 4 – Printer Profiling
Yet to come
I have these first 3 Articles copied and formatted into Word documents for easier reading if anyone would like a copy.
If you produce digital images, and are interested in learning something about taking control of your process, then come along on Thursday 5th March to hear what these people have to say. Hopefully it will be worth your while and at just $5 admission to help cover costs it is much cheaper than attending a seminar in Brisbane!
by
Ken Sparrow
The planning for a presentation to GCPS members on Colour Management looks to be nearing completion.
We will be holding a special extra meeting on Thursday 5th March at KOA to hear a presentation organised by Sanjoy Banerjee, Business Development Manager for “DES”of Melbourne and Sydney. “DES”are the distributors for the ColorMunki colour calibration equipment from X-Rite (incorporating Gretag Macbeth) who also make the “Huey” (and the Eye-One Display).
Sanjoy will be bringing with him a rep from Ted’s in Brisbane (Cameron Attree, (Master of Photography) and will be giving part of the presentation. The presentation with cover both the calibration of monitors and of printer/paper/ink combinations
Our interest in the “Colormunki” comes from the fact that it is a 3-in-one device that enables the calibration of Computer Monitors, Printers and Digital Projector displays.
We purchased one last year prior to our hosting of the 2008 InterClub Competition for Digital Images and now use it to calibrate our laptop and digital projector combination for consistent display of our digital images (or at least we try - as some people are not happy with our efforts).
Sanjoy claims that with a properly calibrated system one can produce good colour prints using quite modest printing equipment.
If you are like me and use a commercial printer to make your prints it is also essential to know which colour space is required for your images (usually sRGB and not RGB if they are using the Fuji Frontier machines) and also to be aware that as the print is viewed in reflected light is will generally look darker that the transmitted light image on your computer screen.
Also, as projected images are viewed using the sRGB Colour Space, there is little point is submitting images in the RGB Colour Space (or with no colour profile at all) if you expect to see no changes from what you saw at home on your monitor.
An RGB image can look quite “muddy” sometimes when projected in the sRGB Colour Space. Also you need to be aware that many monitors cannot even display the wider range of colours encompassed in the RGB Colour Space.
Having said that, in our competitions one of the most common problems as that some images do not seem to have had the most basic of “Levels” or “Curves” adjustments. They do not exhibit a good range of tones – from black through to white – and they lack contrast. Consequently they look “flat” and/or “muddy “ when projected.
More to the point, without a calibrated display for your monitor and the use of an appropriate colour profile for your image, then it becomes a matter of luck as to whether your print or projected output actually matched what you saw on your own computer monitor.
We are not promoting the ColorMunki, nor suggesting that everyone should rush out and purchase one, but hopefully hearing the information that will be presented on the importance of Colour Management in dealing with your digital images then you will be in a better position to decide what is the best approach for you to follow.
Sanjoy is organising an “Unrestricted” licence for our ColorMunki software so that GCPS members can borrow the calibrator and install the software on their own computer and carry out a calibration of their own equipment (monitors, printer and paper combinations and projector if you have one).
Obviously it is not going to be practical for 70 members to be carrying out monthly caliubrations of monitors and printer/paper/ink combinations on a monthly basis using the one calibrator. However we plan to make it available to GCPS Members to use for a day or two at a time.
No doubt Sanjoy is hoping that some people will subsequently go out and purchase one of their units.
For more information go to ColorMunki:
http://www.colormunki.com/
Colour Management Information:
There is also a recent series of articles Introductory Articles on Colour Management on photo.net (http://photo.net/ ) by Jay Kinghorn on Colour Management in which the X-Rite Eye-One Display and ColorMunki are both discussed.
Part 1 – Colour Management Overview
http://photo.net/learn/digital-photography-workflow/color-management/
Part 2 – Monitor Profiling
http://photo.net/learn/digital-photography-workflow/color-management/monitor-profiling/
Part 3 – Colour Settings
http://photo.net/learn/digital-photography-workflow/color-management/configure-color-settings/
Part 4 – Printer Profiling
Yet to come
I have these first 3 Articles copied and formatted into Word documents for easier reading if anyone would like a copy.
If you produce digital images, and are interested in learning something about taking control of your process, then come along on Thursday 5th March to hear what these people have to say. Hopefully it will be worth your while and at just $5 admission to help cover costs it is much cheaper than attending a seminar in Brisbane!
by
Ken Sparrow
Setting up your own website
03/01/09 21:39
EVER THOUGHT ABOUT A WEBSITE FOR YOURSELF?
by our new Pres...Jeff Hutchison
For those who are interested here is my experience of trying to set up a web site when you don’t know a razoo about anything web related.
I have all these pics that just sit on my puter, some I even print out, sell the very occasional one, hang on the wall or give away, some sit in a drawer never to see the light of day again.
OK I put them in the club comps and I put them in the odd comp here and there and exhibition if I think they are good enough but I still have them all, what to do with them was the eternal question.
I know, I’ll put them on a web site somewhere.
Don’t trust any I see that are for free!!!!. I’ll get my own.
What’s the cost? what’s involved? Where do you start? I don’t know anything about HTML aaaaagh!.
So it sits in the back of my mind for a loooong time.
Well, after a couple of bourbons one night it comes back into my head, so, Google, everyone’s best friend on the web, is put to use to find a web site for me to utilise, but where to start, how does it all work? Which is the easiest program to use? How much does it cost? Am I being ripped off? Aaaaarg!
FIRST, A URL (like I know what that means...)
After a couple of weeks studying this site and that site I discover that first you have to have a URL, this is a web site name. Is this easy? Well you will find that a lot of what you want is not available cos everybody in the universe has used up all the names that you would really like to use.
Where to look? Try www.GoDaddy.com at least for a place to start. I settled for an Ozi site www.Ezypages.com.au but what do I know.
Well I decide to sign up and off I go. The web builder at the other end wants to know what colour do I want the pages, what colour do I want the fonts (not all are available by the way, you take a chance if you stray off the norm) and how do I want to set up the pages.
So off to the World Wide Web again to check out other photographic sites (there are quite a few) and I finally come up with some sort of idea. All this information is related to the faceless person at the other end of wherever I am sending my e-mails; does anyone ever really know? And somehow a draft is agreed upon, e-mails are sent back and forth, some pics are sent to set up the pages and then I am now told I am “on the web”.
It looks like *%#$ and I am left to try to figure out how I am to add pics to the pages I have been allocated.
E-mail after e-mail trying to come to grips with the program is sent, information is related back to me and I am none the wiser, I feel like an idiot not understanding what (I suppose) is pretty simple to one who knows and thinking of asking my nine year old grand-daughter, kids know these things.
It took me two weeks.
It also took me to the point of desperation, when on a Friday night, after yet another night of frustration, I sent an e-mail stating that I had made a mistake, would go and do a uni degree in computer science and come back in a couple of years.
I was resigned to this fact and was at last feeling comfortable with myself once again and not having nightmares, when on the Sunday, again after a few bourbons, (I love the stuff) I decide to have “one more look”.
Have you ever had the experience of a haze just coming into view? Something clicking in your head, or a feeling of great relief, Well I have, it just hit me and I was off and running at least getting the site to a stage where I am not ashamed of it.
Have you ever noticed time stands still on the computer?
It was one o’clock in the morning when I decided I had done enough and should maybe go to bed; 5.00am came really quickly that day.
Do I know everything? Not a chance, but am I having fun? You bet.
Is it worth it? Well it was/is for me, it may not be perfect at this time, but it is a work in progress and now it gives me something extra to do with my images and gets me “out there”
Check it out and give me your opinion, good, bad or indifferent.
www.ajhfoto.com.au
Cheers
Jeff Hutchison
(President)
The Photographic Triangle
23/12/08 15:48
THE PHOTOGRAPHIC TRIANGLE
STOP SHOOTING AUTO
A year ago when I bought my first DSLR camera it was quite daunting trying to understand the terminology involved as it was a new language to me.
I was determined from day one that I would start shooting in MANUAL mode!
In order to do this I needed to do a lot of reading to come to terms with the relationship between f-stops, shutter speed and ISO settings. The reference material which helped me was a BLOG I discovered on the internet called “Stop shooting in Auto”.
Here is the link: http://stopshootingauto.com/exposure-lessons-in-order/
This is an excellent reference tool containing a series of exposure lessons to help you understand how your camera works.
CAMERA DEMONSTRATION
Another useful link I found was a fun interactive one with a camera, where you can choose the exposure mode, f-stop, shutter speed, ISO and exposure compensation and actually see what result this will have on the picture. You can also choose the light (illumination) level.
Obviously this is just a guide and the best thing you can do is to grab your camera and shoot away!
Here is the link: http://www.pixelpoppin.com/camera/index.html
ENJOY.
Sue