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Oldies but Goldies - part 2 of 1 2 3

Published 01/04/2011

Slightly miffed at our inability to knock off the article without having to go out in the cold, we set off to the Liverpool Waterfront, armed with a bag of old lenses, a few new ones and a big tripod.

Real-World Testing
As luck would have it HMS Liverpool, a type 42 destroyer, had just docked and provided an ideal test target. We shot from across the river, a distance of exactly one mile; weather conditions were reasonable - bright mid-day sun with just a hint of haze. Each lens was used at f5.6 and manually focused close to infinity. A tripod was used.

The RAW files were made at 200 ISO and processed in ACR. Some exposure corrections were needed and the modern 105mm Micro-Nikkor had a distinctly warm cast (which we left uncorrected); other than that, only sharpening was applied. For this we used a pre-sharpen in RAW using settings of: Amount 50, Radius 0.6, Detail 80 and Masking 0. This represents an 'average' type of sharpening we would employ for a scene such as this.

The images were cropped in the centre so that composite prints could be made, collecting together similar focal-length groups into a single file for printing. These were then postsharpened using the techniques outlined in Professional Imagemaker (Sept 2010). We found that a High Pass opacity of around 30% produced the best result with the slightly higher ACR setting employed.

The results showed that at 105mm it was possible to resolve a Marine on the decks of the ship and differentiate his head, arms and legs but not detect if he was armed (they usually are!). At 85mm you could just about tell that the shape was a person but nothing more. This is in accord with our calculations. At the distance of a mile a 250mm-wide human head would be represented by about 2.4 pixels height, roughly four or five pixels in total for the head. In other words we were at the limit of the sensor resolution. By the same token when the warship was imaged at 12mm focal length the entire ship was represented by just 117 pixels and you could not say for certain what class of ship it was, although you might have guessed it was a warship.

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1st Published 01/04/2011
last update 09/12/2022 14:57:05

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