On 29-Aug-18 6:22 PM, Mark Doering-Powell, ASC via Cml.News wrote:

I’ve been looking into sources for zoom lenses that have been coated
for InfraRed shooting - or how difficult it would be to coat lenses
for it.

I have done a lot of work shooting IR. There is a fundamental issue with
zoom lenses that in most cases make them unsuitable for use with infra
red illumination. It comes back to the fact lenses are designed and
optimized for visible wavelengths. The much longer wavelengths of near
infra red, 0.75–1.4 µm means that the internal spacing between lens
elements is not optimized for the wavelengths used with IR
illumination.  Given zoom lenses have many more elements than prime
lenses this causes more issues, often halos, flares and generally soft
images. So I generally stay clear of zoom lenses for this reason.

There is also an issue caused by internal reflections from the interior
of the lens barrels when IR light is reflected where visible light is
not. Again causing flares and halos and  central spots.

I find that simpler the lens design the better the results. Often older
prime lenses give best results, especially early Zeiss prime series or
older (FD series) long (300mm plus) Canon prime still lenses seem to
work quite well. (possibly because of simpler coatings or barrel design)

It is also advisable to use IR band pass filters in front of the lens to
block visible light and only allow the specific IR wavelengths you want
to pass.

There is a website that contains a lot of information re IR/UV shooting
for stills and video. https://www.lifepixel.com/

Mark Lamble ACS DP Evolve Films Woodend Australia

FYI I have no association with lifepixel but have used their services.

Talk/email Bill Bennett, ASC … who shot that Audi spec spot with the IR Alexa.

https://vimeo.com/93503055

Making of: https://www.youtube.com/watch?v=H6WlczFpnFI


makofoto, s. pasadena, ca

Talk/email Bill Bennett, ASC … who shot that Audi spec spot with the IR Alexa.

https://vimeo.com/93503055

Making of: https://www.youtube.com/watch?v=H6WlczFpnFI

***********

You can see the added IR flare and haze …

Can your post use the Adobe De-Haze function to help with the veiling?


makofoto, s. pasadena, ca