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Notes on the Lens Assessments
All lenses had their focus set to infinity for hot-spot assessment. Because infrared backfocuses with most lenses, this means that actual focus in infrared was slightly beyond infinity. Nevertheless, focusing at infinity allowed a consistent methodology for each lens, since there is always an infinity mark to reference.
For all lenses with filter sizes up to 77mm, an Expodisc (“Classic”) was used to create a uniform image [image]. The dark corners with some lenses (especially wide-angles) are due to the 5mm or so of intrusion by the ExpoDisc into the image circle. Newer versions of the ExpoDisc appear to intrude less on the image circle. For lenses with larger filter sizes, such as the 50-300 ED, a sheet of vellum was placed directly over the lens front.
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Diglloyd Infrared Photography covers cameras and lenses for infrared photography.
The coverage explains all the issues involved in shooting for monochrome and in infrared. It is not a review of any particular camera or lens, though many examples are included.
- Monochrome vs color cameras.
- Post processing for monochrome.
- Guidance on workflow for infrared, including black and white and channel swapping for false-color images.
- How infrared renders, and why certain spectral cutoffs matter: false color vs black and white.
- Image quality issues to be on the lookout for in infrared.
- Numerous lens evaluations in infrared.
View an overview of infrared as well as filter spectral transmission plus examples from an optimal lens.