‘Deep’ Infrared photography using a 850 nm filter over the lens of a 720 nm or other converted DSLR: Handheld Shots

The one drawback of using an 850 nm filter over the lens of a DSLR converted with a filter of a lower cut-off (e.g. 720 or 590 nm) is that the viewfinder is completely dark. On a tripod it is an easy matter to align the camera, screw the filter in place, and adjust the exposure.

With later Nikon DSLRs models, like the D90, the solution to using the camera off the tripod is easy: use Liveview, However, ready-converted Nikon D70s and D80s are popular in UK especially for those trying infrared photography for the first time. With no Liveview it would seem there is no way that they could be used with an 850 nm filter for hand-held photographs. But there is a way: put a cheap direct vision finder of the type used for rangefinder cameras in the accessory shoe and use that to line up the shot when the filter is in place—not to frame the shot necessarily but to align the camera to the central point already identified without the filter in place.

The procedure then is simple: Without the 850 nm filter, frame the shot through the normal reflex finder and remember where the central point of the photograph lies in the scene (easy with a central focus point showing in the finder); add the filter and then with the direct finder aim the centre of that finder at the spot identified earlier, and take the photograph.

Provided you aim for the centre it does not matter what focal length the direct vision finder is simulating, although it does help if the frame of a longer focal length lens is outlined. To reiterate the finder is being used as a direction indicator or gunsight, not as a means of framing the shot. This method works, of course, for all manner of zoom and fixed focal length lenses since the frame shown is of no concern.

The photographs show a brightline finder fitted to a Nikon D80. The central point is easy to see because of the marking for a 135 mm focal length lens (on what it was designed for, a full-frame 35 mm camera). Incidentally, I do not recommend the finder shown (Helios, made in Japan); a poorer article it would be hard to imagine since it was poor in both design and construction. I got this some time ago from an eBay seller but only got round to using it more recently. The first thing I noticed was the name ring seem misplaced but then I saw that the frame were moving around inside the finder. I took it apart. It had been crudely glued but the non-original as well as the original adhesive had come unstuck so that the frame (on a piece of film and glued between two bits of glass) was rattling about. Fastening it back in so that the centre of the view was at the centre of the frames was not easy since there was no fixed point for attachment. I assume the factory must have had some sort of jig to drop the film-glass sandwich onto drops of glue. I put the whole thing back together, aligning the frames by eye, and it does now align with the centre of the proper viewfinder (at what is effectively infinity) pretty well spot on.

‘Deep’ Infrared photography using a 850 nm filter over the lens of a 720 nm converted camera

I have repeated the trials I did with an 850 nm filter on my 590 nm-converted Nikon D80 with my new-to-me 720 nm-converted D90. I needed to increase the exposure by two stops compared with the value metered by the camera without the filter in place; as before I had to do this on manual because metering through the filter produced nonsensical results.

‘Deep’ Infrared photography using a 850 nm filter over the lens of a 590 nm converted camera

For black-and-white infrared photography I wanted to get darker blue skies and whiter foliage than I could using my converted Nikons with 590 and 720 nm filters over the sensor. So I bought a cheap 850 nm filter to fit over the lens. The grand total of £19.99 paid to an eBay seller soon had a made-in-China Zomei 77mm 850 nm filter arriving by post.

The only disadvantage of this route to ‘deep’ infrared photographs (actually ‘near’ infrared to physicists) is the opacity of the filter. You have to work with a tripod, frame the shot and then screw the filter onto the lens before pressing the shutter. Since I will use it for non-moving subjects the addition of the filter is only a slight inconvenience.

First of all I checked what exposure I would need compared with the exposure metered by the camera without the filter. I soon found that with the filter in place my 590 nm-converted camera on aperture priority over-exposed by about 6 stops, as you would expect since the meter is working somewhere in the visible light range. Kolarivision suggest a light loss of about 1 stop with their 850 nm filter. Sure enough, when I made a series of test shots at 1/3rd stop intervals in sunlight, 1 stop over the metered exposure was the best. However, 1 stop is the starting point for adjustment up or down depending on the amount of infrared radiation relative to the amount of visible light coming from the scene.

I keep my 590 nm-converted camera at minus 2/3rd stop (-0.7) exposure compensation (slightly less than suggested by Kolarivision for their 590 nm conversions). For convenience when using the  850 nm filter I now turn compensation to 0, take the metered reading on aperture priority, switch to manual exposure and add 1 stop. I also focus manually before adding the filter.

The two photographs, from my usual test site of out of the bedroom window, below show black-and-white conversions in Lightroom from my 590 nm converted Nikon without and with the 850 filter.

Infrared Processing in Lightroom

If you have your RAW image from an infrared converted camera in Lightroom, having to go to Photoshop or Photoshop Elements with Elements+ to swap the red and blue channels is a pain. When I made the move from Aperture to Lightroom 6, I was delighted to find, in a Google search, Jarno Heikkinen’s solution to the problem on his Capture Monkey website. His download provides Camera Calibration Profiles with reversed colour matrices for a number of cameras. To reiterate, it simply extends the profiles available within Lightroom. It does not, of course, work for jpegs.

I also remembered that Jason O'Dell had described an approach similar to, but easier than, changing Hue in Nikon Capture 2 using Viveza 2 (I have Nik Software as a plug-in for Lightroom).

I thought I would compare the basic conversions using these three methods. The starting point was a NEF image from a converted Nikon D80 with a 590 nm filter over the sensor.

As you can see there are differences from the same raw image. All I have done is to apply the conversion and then in Lightroom use Auto Tone. I have not done any further processing.

A Lightroom 6 to Photoshop Elements with Elements+. Red/Blue Channel Swap. Auto Tone in Lightroom

B Lightroom 6. Camera Calibration Profile Red/Blue Swap (Jamo Heikkinen). Auto Tone in Lightroom

C Lightroom 6. Edit in Viveza 2. Near 180 degree shift in Hue. Auto Tone in Lightroom

I then did a simple black-and-white conversion within Lightroom and these are the results:

Which method you prefer depends on the final look you are trying to achieve and how easy it is to get where you want to be. Each provides the starting point for further processing both in colour and black-and-white. For most purposes, particularly black-and-white, and at the moment I think I can manage with the wholly within Lightroom solution of Jarno Heikkinen, although for some faux colour images I rather like the Viveza 2 process. Whether or not I can manage completely without the channel swapping step in Photoshop time will tell as I try images with the different cut-off filters over the sensors of my converted cameras, with different white balance settings, with additional external filters and with different lighting.

How to—and how NOT to—get started in Digital infrared Photography

First rule: do not start with magazine articles such as those that have appeared in Amateur Photographer. Even a reader of the natural home of the head-in-sand luddite wrote to complain how misleading one article had been.

Second rule: Use the information available on the internet. It is far better than anything I have seen in a magazine both on taking and processing infrared images.

Third rule: Do not simply buy an IR filter and try it on an unconverted camera. The sensors of many cameras have virtually no sensitivity to the infrared end of the spectrum.

Fourth rule: To get started buy an infra-red converted Nikon D80 or D70 for £120-200 from the many available on eBay UK. You will pay much much less than the price of a conversion. This route has been completely ignored by the magazines. Could it to protect their advertisers? Also check which Nikon lenses are suitable for infrared since some show ‘hotspots’ on the image. Canon bodies—if you are that persuasion—are also available but less commonly than the old Nikons. Again check on websites which lenses are not suitable. The advantage of the old DSLRs over many converted compact cameras (also freely available on eBay) is that they offer RAW rather than just JPEG output, thereby offering greater opportunities for processing.

Fifth rule: If you do not want to pay for the full version of Photoshop to do channel swapping, use Photoshop Elements and buy Elements+ for US$12 which unlocks that capability.

These are some of the websites I found to be particularly useful in getting me started:

Lifepixel  and Kolarivision (good advice and guidance on their own conversions, filters and processing). Also this tutorial guide.

There are many other websites but some which were useful in the past are now out-of-date.

'Bridge' Cameras for Wildlife. A Retailer Gets the Message

The 'photographic' magazines may ignore 'bridge' cameras and only mention them in passing as new models appear but those of us who travel thousands of miles to see wildlife and natural habitats know what most travellers will be carrying: a superzoom bridge camera.

I see some in the photographic trade have now realised that the are not just selling to 'photographers' (the term is hard to define but I tend to think of amateur photographers as people who take photographs that are acceptable as photographs by other amateur photographers) but to naturalists who take still photographs and, sometimes, video. This advertisement from WEX arrived in an e-mail:

However, I am not sure they quite have the message. A 10.7x optical zoom is usually nowhere near enough.

The Nikon Coolpix P610 and Filters. What size and if at all?

Search as I might I could not find the filter size for the Nikon P610 in the manual. So I looked online and uncovered a whole can of worms. Somebody had enquired of Nikon the same question but had been told the P610 would not take filters, that the grooves inside the lens mount were not threaded and that any filter would only be lodged there and would fall out. Then somebody else stated that their 52 mm filter fitted fine.

Having a 52 mm filter in my hand (see previous post) I tried it on the P610. It fits perfectly. Firm as a rock. No problem at all. Here I am trying and failing to dislodge the filter other than by unscrewing it:

Problem solved but what were Nikon thinking of when they produced the camera and the manual?