First some practical rule I use: I call it the 10/10 rule:

At f/1, 10mm the hyperfocal distance is 10m.

To get to real situations:

1. Divide 10m by the f-number you want to use (example f/5.6 gives ~1.8m)
2. Compute the square of your focal length and divide by 100 (example 28mm * 28mm ~ 800, hence 8 )
3. Multiply the two results (example 1.8m * 8 = 9.6m)

This rule is reasonably exact, you can use it as well to find the right aperture (the near-field is roughly half of the hyperfocal): Say, you have a 50mm lens and need everything from 10m to infinity in focus.

1. Multiply the min focus distance by 2 (example: the hyperfocal is then 20m).
2. Divide the lensfactor as computed in (2) above by the hyperfocal distance (example 50*50/100=25, 25/20 = 1.25m)
3. Multiply by 10 to get the required aperture (example 1.25*10 ~ f/13)

You can shorten this by dividing the hyperfocal distance by 10 and execute only step 2, this gives numbers that are easier to compute.

This approximation is designed for “normal” APS-C cameras with a pixel-pitch of ~5µm. To be fair this makes sense down to f/8 - for smaller apertures the diffraction will get you unreasonably long hyperfocal distances. I recommend to fix the algorithm by setting the start distance of 10m to 8, 6 or 4m for f/11, f/16 or f/22.

What is hyperfocal distance?

Glad you ask, without much ado, hyperfocal distance is the focus distance from there even objects at infinity will still appear sharp. It is computed as

H = f*f/N/c + f

where f is the focal length, N the f-number and c the diameter of the circle of confusion (CoC)

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A common knowledge item in photography is that tele-lenses allow you better subject separation. I had been interested in how much we are talking about.

You have for sure noticed that the subject separation (aka DoF, Depth of Field) is more pronounced at close distances. To make things comparable we have to define comparable scenes and from a photographer’s point of view the common denominator is the magnification. In common portrait scenes you have a magnification of 1:10 to 1:100. This means that that 1cm (or inch) on the sensor will represent 10 to 100cm (or inches) of the subject.

The basic optical formula tells us that the magnification is the relation of the subject distance and the focus distance. The constant coupling these lengths is the focal length of the lens. Short: Double the focal length and all other lengths will have to double too. If you shot your friend so that the face fills the whole frame with a 50mm, your will have to step back four times as far to achieve the same with a 200mm lens.

Here two images shot at 70 (right) and 210mm (left). The magnification of the subject is roughly the same and both pictures had been taken at f/5.6:

This comparison makes it easy to see the difference: The diameter of the bokeh circles on the water is three times wider. In other words: The blur that causes the subject separation is proportional to the focal length - at constant magnification and aperture!

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I am thrilled by the new Sony A77 DSLR and its advanced kit lens SAL1650, a 16-50 f/2.8 zoom.

As I decided about my gear I ended up with Nikon’s D90.

Nikon failed so far on me by not delivering a D300s successor  (D400). The D400 will be very likely to use the same sensor like the A77, but will there be much to ask?

The weakness of Sony’s line up had been the lenses - either mediocre or quite good, but overpriced (Zeiss lenses). The combination Sony just announced seems to priced of what I expect to be the price of a D400 body.

If the image quality of the new combo will hold up against its technical parameters, Sony has a killer here

This last of a series of what glass you will need. Now all lenses are through, it is just left what we can put in front to them.

If, why …

First screw off the UV/protection filter and tuck it deep into your bag for the visit of a steel work in full production. Filters degrade IQ. In daylight it is less visible, but once you botched some night shot in the winter where you stood freezing at -10°C, because all exposures caught an inexplicable flare you know better.

If you are really concerned, get a high quality filter from Tiffen, B+W, Heliopan or Hoya (Hoya sells different grade, do yourself a favor and buy the most expensive one). UV is not an issue, clear filters are what you want. Prepare to spend €50 for a 77mm filter.

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This is part VIII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

Any lens can double as a macro with close-up lenses and extension tubes, BUT most normal lenses don’t  perform best at close focus and adding close-ups/extensions will push macro lenses even further. Short macro lenses often don’t go to 1:1 magnification, they are close focus lenses for exaggerating perspective. Useful focal lengths are 60-200mm. 1:1 magnification is always reached at four times the focal length, so do the math what working distance you get and how to do lighting (At 1:1 you loose 2 stops that have to be taken into account as well for the diffraction limit). All macro lenses are good, a smooth manual focus ring is a big help. So you should get a 200mm macro? Yes, if you are really serious about it and can wait that some renewed version comes out. Nikkor 105/2.8VR and Tamron 60/2 are exceptional lenses at the moment. The VR is useless in macro range, btw. -the back and forth movements can’t be corrected by VR and AF will give up as well.

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This is part IX of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

There are three kinds of special lenses:

• Fisheye
• Effect lenses
• Perspective Control (PC)

They are special, for special application, so you will need them rarely unless you already specialized in a special field.

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This is part VII of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

Wide zooms (below 35mm FX/24mm DX) obliterated the wide angle primes.  Besides the obvious goal of getting a large field of view, getting dramatic perspectives by getting really close is what makes these lenses so interesting.
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This is part VI of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

Tele zooms cover the range 70/5omm+. Candid shots, sports, wildlife are typical applications (adding a close-up lens makes most of them as well capable macros).

Almost all tele zooms are actually too short for wildlife. You need at minimum 300mm here + some feature like AF lock are handy.

It is fair to categorize in three groups

• Consumer tele
• Pro tele
• Long tele

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This is part V of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

Zoom lenses are are rather modern concept that came with the SLRs going consumer. The first zooms had a moderate zoom range and rather small apertures - in film zoom lenses were much more popular and of much higher quality. The marketing was more “Get two (three) lenses in one” appealing to the casual photographer how didn’t carry a bag with all the gear or had different bodies hanging around his neck. Who ever tried to mount a M42 lens while walking quickly sees the benefit.

This class of consumer zooms still exists, but it had been complemented by pro-class zooms that obliterated prime lenses in many applications or even outperforms them.

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This is part IV of a series of what glass you will need. Each part will discuss a certain lens type and its applications.

Medium primes are lenses in the range of 85-200mm (in FX terms) or 58-135mm in DX.

This segment is very interesting as you find here lenses with with the lowset f-number/focal-length (if we neglect long tele lenses). In other words: These lenses allow for extreme subject separation.

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