Luminous Landscape Forum

Equipment & Techniques => Digital Cameras & Shooting Techniques => Topic started by: marton on September 02, 2016, 10:12:23 pm

Title: Infrared
Post by: marton on September 02, 2016, 10:12:23 pm

I've sent my Fuji X-T1 away for an infrared conversion. I've chosen 850nm, and was wondering if anyone else has an 850 conversion and the differences seen, if any, between it, and a 720. I know the difference in technical terms but was just wondering in terms of perceived image difference.

Title: Re: Infrared
Post by: Telecaster on September 03, 2016, 03:41:27 pm

In my experience a 720nm cutoff mainly gives you some channel-to-channel differentiation to work with should you want to try color IR. At ~850nm the color filter arrays in cameras I've done IR with have been effectively transparent.

-Dave-

Title: Re: Infrared
Post by: Jim Kasson on September 03, 2016, 04:14:22 pm

Quote from: Telecaster on September 03, 2016, 03:41:27 pm

In my experience a 720nm cutoff mainly gives you some channel-to-channel differentiation to work with should you want to try color IR. At ~850nm the color filter arrays in cameras I've done IR with have been effectively transparent.

I agree with that. That means you can use channel balancing for B&W conversion with no interpolation. However, that doesn't help materially unless there's no AA filter in the camera.

I've also found that the exposures at 850nm are much longer, but I guess that depends on the subject and the sensor.

Jim

Title: Re: Infrared
Post by: marton on September 03, 2016, 10:05:04 pm

Thanks for the replies. I've done a little research after reading these, and it seems that yes, the 720nm and below will allow for channel swapping and faux colour work, whereas the 850 conversion will give me results as close to those which come with black and white infrared film. I think I'm going to stick with my choice of 850 as I dislike the look of infrared faux colour. I'm a fan of Minor White after all.   

Title: Re: Infrared
Post by: Osprey on September 04, 2016, 01:08:34 am

Note that shorter wavelength IR can also work well for black and white work.

Title: Re: Infrared
Post by: Herbc on September 04, 2016, 11:59:05 am

agree with the 850. I have had 3 cameras converted over the past few years, now A7R, looks like it will be the last.  Focusing is challenging with some lenses. 8)

Title: Re: Infrared
Post by: Telecaster on September 04, 2016, 03:17:42 pm

I too prefer longer near-IR wavelengths for b&w. 850nm seems to be a good cutoff choice for current sensors: you can neutralize the CFA without blocking many useful photons.  :)

-Dave-