Optics

For this (long) blog entry, I want to explore a little bit about optics and how it affects us photographers. It will be part of a series of blog entries about optics. With the more high resolution sensors and high density sensors being brought into the market, I was curious to see how the laws of physics will limit high resolution photography.

The first concept that is required to be covered is that of the Airy Disk. Now, Wikipedia covers this topic quite well, and I will try not too verbose. But very simply, the airy disk is an optical phenomena. It is the result of an optical system unable to reproduce a point source as a true point. Instead, it appears as an airy disk. That is, a point source, technically having no linear dimensions, becomes a circular disk of a finite and definable size. The size of disk is depend on a few basic parameters of the optical system - aperture and wavelength.

But for photographers the most important aspect is that the size of this disk is proportional to the f-number. The larger the f number (i.e., smaller the physical size of the aperture), the larger this disk becomes. The table below shows the airy disk size for different wavelengths of light as it changes with the f-stop. The units of the airy disk is μm, and for the keen reader, you will also note that most sensor pixel pitch is given in μm. 

Aperture	350 nm	450 nm	500 nm	750 nm
f/32	13.7 μm	17.6 μm	23.4 μm	29.3 μm
f/22	9.4 μm	12.1 μm	16.1 μm	20.1 μm
f/16	6.8 μm	8.8 μm	11.7 μm	14.6 μm
f/11	4.7 μm	6.0 μm	8.1 μm	10.1 μm
f/8.0	3.4 μm	4.4 μm	5.9 μm	7.3 μm
f/5.6	2.4 μm	3.1 μm	4.1 μm	5.1 μm
f/4.0	1.7 μm	2.2 μm	2.9 μm	3.7 μm
f/2.8	1.2 μm	1.5 μm	2.0 μm	2.6 μm
f/2.0	0.9 μm	1.1 μm	1.5 μm	1.8 μm
f/1.4	0.6 μm	0.8 μm	1.0 μm	1.3 μm
f/1.0	0.4 μm	0.5 μm	0.7 μm	0.9 μm

For the purposes of comparison, we shall use the longest wavelength in the visible spectrum (which ranges from about 350nm to 750nm) which is around 750 nm - red light. The assumption is that we are working with colour images in the full visible spectrum (no UV or IR photography, but the formula and concept apply equally). We want the take the most stringent criteria - that is the airy disk being the largest in the visible spectrum. Form this point onwards, all the various commentary and tables will be based on the airy disk at 750 nm wavelength of light.

What this airy disk describes is that no matter how good or perfect the lens, the highest resolution possible if limited to the size of the airy disk. This is where diffraction limit comes in. Any optical system in which the ability to render a point souce is only limited by the airy disk, is said to be diffraction limited.

To make another conclusion, if the airy disk size for a given aperture is less than double the pixel or sensor size (i.e., to capturean airy disk requires four pixels, two in each direction), it too is said to be diffraction limited.

Monument

Nikon D700 with 24mm f/2.8 (ISO 200 f/2.8 1/5000)

From memory to today

Remembering back to the old film days, I tried to remember what was my favourite gear to use. Long trip down memory lane later, I felt that for me, the Mamiya 7 and Contax T3 was a perfect fit for me. One was ultra high quality images using 6x7 film format (the film, or sensor was 56x69mm) and the other was ultra portable and high quality. Both cameras were so simple to use, and devoid of any 'frills'. Just the way I like it. So further to that, I wanted to find an equivalent in this digital era. I came up with the following.

• Leica X2
• Leica M9-P or equivalent full frame rangefinder.
• Leica 21mm f/3.4 Super Elmar
• Zeiss 35mm f/2.0 Biogon or Leica Summilx f/1.4
• Leica 75mm f/2.0 Summicron or f/2.5 Summarit

Pier

Another photo when I was out on a nice (cold) stroll by the beach.

Olympus E-510 14-42mm  f/3.5-5.6 (ISO 100 f/10 1/500)

One of my interests is in macro flower and plant photography. This was taken at the Melbourne International Flower Show in 2010. Handheld shot with the D700 and Nikon 60mm f/2.8 Macro. Part of The Compact Photographer is to be able to capture these kinds of shot (ones that I enjoy, and hope you will also) with easy to carry gear. I went with my young family and given the crowds, it would've been impossible to us a tripod or larger equipment. I went with just one camera and one lens. Easy.

Nikon D700 with 60mm f/2.8 AF-S (ISO 450 f/5.6 @ 1/125)

Sample Shots with OM-D E-M5

Here are some of my first shots with the Olympus OM-D E-M5 using the 12mm f/2.0 and the Panasonic Leica 45mm macro. They were shot as RAW and processed in Aperture. Post processing has been applied - I am not interested in what I get directly out of the camera, but what I can get out of the files.

Olympus OM-D E-M5 with Olympus 12mm f/2.0 (f/4.5 ISO 200 1/500)
Taken from the apartment balcony. Possibly a little over sharpened. But again, look at the detail in the windows and the metal balustrades. 

Olympus OM-D E-M5 with Leica 45mm f/2.8 (f/2.8 ISO 250 1/100)
Look at the focus point - it sits between the 5.6 and 11 aperture indicator on the right. You can see the small surface of the 12mm lens. Super sharp. Also move the creamy background.

What is a Compact Photographer?

No, I am not referring to a photographer who is physically compact… The Compact Photographer refers to who in which their equipment allows them the utmost flexibility and mobility when catching that 'decisive moment'. Another words, a photographer who can go anywhere and take any photos they desire. Be it a sweeping panoramic or a gentle portrait of their family, through to a extreme macro in the middle of the Amazon. The Compact Photographer is one who isn't encumbered by their equipment.

To this end, the very nature of each compact photographer is different; but their differences are not rooted in their equipment, but rather in their style and context. Inevitably, the question of equipment does come into play at some stage, but to be honest, that is not the hardest question. For me, the hardest question is what do I want to achieve with my photography [today], and as a philosophical realisation of The Compact Photographer; what is the least and lightest (i.e., compact) equipment I can carry to achieve that.

For the above statement and basis to the definition of The Compact Photographer, I shall be discussing over the next few months, and I hope will provide some thoughtful ideas and commentary on what I have espoused.

The Compact Photographer

My journey in photography begun in my early teens, when I discovered my father's Nikon EM SLR with the 28mm and 50mm E series lenses. From the first moment of learning to use the camera, taking the first photo and receiving the first prints; I was hooked. Call it a hobby or what you will; but since then I have been an avid photographer and seriously guilty of the 'gear acquisition syndrome', or GAS.

Through the many years since the EM, I have used almost every conceivable system under the sun. Everything from a Toyo 45 view camera to travelling round the world with a Contac G to Nikon/Canon/Contax/Leica/Olympus 35mm systems; through to Mamiya 6 & 7 and Hasselblads and all the way to my current setup. I have probably used it all. Prior to the advent of the digital medium, I primarily shot with colour E6 (or slide film) and black and white (mainly Ilford Delta 100 and 400) and process my own B&W film. But now, I am solely a digital shooter - mainly for convenience and cost.

Through the many years I have done a bit of travelling both locally, in Melbourne Australia, and internationally. One thing that has been the thorn in my side was the weight and bulk of the equipment. Having once carted the Toyo 45 with 10 DDS, light meter, focus cloth, suitable tripod, etc. on a short 30 minute hike to a water fall and back - now older and wiser - will never happen again!

My quest since then, like many other photographers out there, was to find the ultimate system that was able to deliver high quality photos, be versatile and easily transportable. This quest and question has been part of my photographic journey for the last 6 or 7 years, and now I want to share this on-going journey with you.

At present, my gear is based around two primary systems; Nikon Full Frame and Micro Four Thirds. My other gear include; a Hasselblad SWC system, Contax RTS system and an assortment of compacts (e.g., Contax T3 and Ricoh GR1s). This is my cumulative collection of gear over the last 20 years. Like many of my peers, I have probably spent too much money on new gear, and lost more on selling them. But, the one (very important) redeeming aspect, are my photos - priceless.

What I would like to do with this blog is to share with you my on-going journey; and share with you some of my images; past and present. I would appreciate and welcome any feedback and my lofty hope is that this blog will be of relevance and a positive resource for the photographic community.