Friday, 24 July 2015

Hot Photography part deux

I blogged recently about my attempts to create a DIY infra red camera.

I left it at the point where all appeared to be working, but I needed filters in order to complete the task and to reduce the amount of visible light that otherwise overwhelm the IR light we wanted.

One of advantages of the DIY approach is that it allows more flexibility in terms of the type of IR images you want to produce. By varying the filters on the front of the camera, you can let more or less visible light through allowing you to play with the effects. You can have an pure IR image, or by allowing a little colour through, you can get a bit of colour as well as the IR part.

I therefore ordered an 720nm and 850nm screw in filter and when I returned from holiday they were waiting for me.

The 1st thing you notice is that the filters appear black, like a ND filter to the naked eye. Of course this is the point, since they only pass IR, which is not visible to the human eye. Mounted on the camera, it is has little effect on the usable image and little noticeable effect on shutter speed.

The 720nm lets a greater amount of the spectrum through, just poking through into the visible spectrum, while the 850nm has a greater cut-off in the IR region, cutting almost all the visible spectrum out(filters cut-off are not perfect and there will always be some leakage).

Yesterday I had my 1st chance to try them out. IR photography works best with warm blue skies (preferable with a little cloud), and at the moment it is a bit overcast (the irony being that I had just come back from Crete where we had 7 days of rich blue skies which would of been perfect for IR photography), but I couldn't wait to try it, so I went to one of my favorite places, which had a old barn and plenty of foliage.

The 1st issue was the white balance. Since my chosen camera does not support RAW, and normal white balance is skewed by IR, I had to manually adjust the WB. Fortunately the camera does have a custom WB feature, and the advice is to take WB from a large area of grass. So with my 720nm filter on that is what I did.

The results were great.The image turned from uniform red, to the IR silver I wanted. These are the 1st images taken with the 720nm filter on.



I have processed them a bit, by compressing the levels. I also tried switching the red and blue channels. Without much blue sky there is not much contrast, but overall I am happy with the result.


Here is a similar image with the 850nm filter on. You can see the greater IR affect, with the corresponding reduction in visible colour.


Remember both these images are in colour, without any B&W processing


Here are a couple other images.  My only issues was some of the images came out out of focus. However I am not  sure whether this is a result of my modifications, the camera or my usage,




So far I am very happy with the results, and I am looking forward to playing with camera and seeing what it can do.

Sunday, 12 July 2015

Hot photography

I've been fascinated for a long time by infra-red photography. Partly it appeals to my inner geek  due to the science involved, partly because I love the surreal landscape and images that it produces, but most of all because I love hacking stuff to make them do cool things.

In the days of film, you could take infra-red photos by substituting normal film for one that was sensitive in infra-read. The results were very high-key black and white photos. Now that effect can be simulated in Photoshop today, but they are not as effective as doing it in camera.

Digital

Due to the sensitivity of the sensor, digital cameras are excellent at recording infra-red wavelengths

The above image (copyright ) shows the sensitivity of camera sensors compared to the human eye. It is is easy to see that cameras sensitivity extend well into the infra-red. In fact they are so sensitive in this areas, manufacturers go to great efforts to reduce that sensitivity.If they didn't photo's taken on digital cameras would look much redder than images seen by the normal eye.

To stop this camera manufacturers put something called a hot-filter between the lens and the sensor that cuts out a lot of the infra-red wavelengths(In fact despite that many DSLR's cameras are still sensitive to infra-red, but require very long exposures to get anything out of them.) and make the actually sensitive more akin to the human eye.

Therefore to take Infra-red  photos, we need to remove the hot-filter in your camera. However once you have done this the camera will only be suitable for infra-red photos so you don't want to do this on your main camera (it is is strange that no main stream manufacturer allows the in-camera switching of filters[I think Sigma did one once, but it is no longer available], it would be a pretty cool feature).


The camera

So basically you need a second camera. The conversion itself requires taking the camera apart and removal of the the hot filter. There are many firms who will do the conversion for you, however these are quite expensive and I'm cheap so I decided to do it myself.

First I  needed a camera.

As a happy accident I had a spare camera. My late father had bequeathed his collection of cameras , mainly were of film vintage,but he did have a Finepix S5700, which as far as I can tell, had never been used.(my dad was never big with computers, which made owning a digital camera relatively useless exercise)



Now this camera is not exactly a Nikon D800, being of a certain vintage and limited to only 7 MPixels (which is less than you would get in a high end mobile phone today), but it was a decent bridge camera in it's day and has some significant advantages.

Firstly it allows you to set a custom white balance. Infra-red skews the standard white-balance, and unless you have a camera that does raw you need to modify the white-balance before shooting.

Secondly It will take screw in filters. More on that later.

Thirdly, being mirror-less you get continual live view. You can do Infra-Red with DSLR's, but you can only see the actual result in live view, which means using the back-screen and not the viewfinder. This camera has a EVF viewfinder which makes it more convenient.

Also focusing is based on the on-sensor chip. A lot of DSLR's struggle to focus in infra-red because they rely on the phase detection chip in the viewfinder, which calculates the light path differently for visible and infra-red light.

Best of all someone had already done the conversion and posted  instructions on the internet.

One thing I did need however to complete the conversion,  was a replacement filter.

Now it is not clear why this is required. It seems that for some cameras, once the hot-filter is removed, they do not focus well unless a equivalent piece of non-filter glass is used to replace it. So I needed to make myself a filter made of plain glass of the same dimensions as the hot filter.

This sounds simple, but glass is not an easy material to work with and the size of the sensor means it was always going to be fiddly.

What I needed was some glass (microscope slides work perfectly here), some method of shaping the glass to the right dimensions and a way of measuring it, I duly purchased  a glass cutter and glass files, a digital micrometer and 50 microscope slides (that was the smallest quantity I could get, but hey, at least I had plenty of raw material. )

Ready for conversion

Duly armed I set about with my task. However I quickly hit an issue. In my haste to do the job I had not actually tested the camera. I had assumed since it was basically unused, it would work.

No such luck. When I put the batteries in, it was as dead as the proverbial dodo. So I was forced to buy a second camera of flea-bay. Not a good start.

Now I had a spare, but non-functioning camera. So I decided to do a trial run on that one.

The dis-assembly  

It's amazing how often you read instructions on the internet and it seems so simple. Normally it is fine until the point of no-return and then goes pear shaped.

I generally have no problems taking things apart. Putting things back together in something akin to the original state I find is the challenge and so it proved in this case.

Taking the camera apart proved quite simple, but I just could not get the thing together. The main issue was the ribbon cables that linked the boards together. They were small, fiddly and just would not re-connect. It took me 3 days until finally I managed to re-assemble the camera (losing only 1 screw in the process).

This was the problem one (copyright  akry.livejournal.com)


However all in all it proved a useful exercise. One other thing I learned was the dimensions of the hot filter given in the original instructions was in fact in-correct meaning I needed to create a new one of the correct size.

The old filter (copyright  akry.livejournal.com)


However it was here that something strange happened.

I decided for no good reason , to test the camera again and to my surprise it turned on. OK, it would not focus, but it showed that perhaps the original issue was to do with the connectors and maybe I could fix it.

So I decided to take the camera apart again, partly for practice and partly to see if I could fix the focusing issues. The 2nd time was a lot easier and to my surprise everything worked....

So if I learnt anything, it is assembling and dis-assembling cameras is not easy  and be prepared to get it wrong.

(see here for a better example of the pitfalls  ),

First Light

So how do you test your camera is picking up infra-red?

Well, just pointing out of the windows may not show much, especially if the camera is getting all the other visible wave lengths as well. The best way is to take a TV remote and point it at the camera while pressing a button. Normally the camera will not see the light, but now you should see the LED flash, like below

Phew, it works
These are the images taken outside, with no changes to the white balance. As you can see they are now a lot redder, due to the extra light from the red side of the spectrum getting through





What Now?


So far so good. But we are a little way to getting those infra-red only shots. The problem is that now the camera is actually getting too much light from the visible end of the spectrum. We are only interested in the infra-red stuff.

What we need is to put a filter on to take the visible stuff away. This was point about why this camera is a good fit for this type of conversion,  since it will allow you to mount a 46mm filter on the front.

I believe if you send your camera off to be converted, they will often replace the hot filter with a standard IR filter. However there are many variations of IR filters, each with advantages and disadvantages.  For example the more light you block off, the longer the exposures will be. By allowing the changing IR filters we have more flexibility on when and where we take our photos.

Generally IR starts at about 700nm. So a 700nm filter will pass all light at a larger wavelength. However filters are not perfect and will pass other colours as well. A 950nm filter will pass far less of the visible light and have a pure IR affect

Anyway I am going to get a 720nm and a 850nm filter to start and see how I get on. Certainly I expect exciting times ahead.

Postscript


Someone has corrected me that it is still possible to purchase a Sigma SD1, and a very interesting (but probably technology dead-end it is). However it could never be called a mainstream camera



Saturday, 11 July 2015

Wyatt Neumann

Sometimes you see someone's work and something just clicks. It makes you stop, look harder and something in your soul say 'yeah!'

That happened to me when I first saw the photography of Wyatt Neumann.

Art often affects us because of a common bond; some common life experience which allows you to see what the other person is trying to express through your eyes and strums a chord.

But in Wyatt's case,it is hard to see any common frame of reference between him and me.

From the outside, he appeared very much the American free spirit, brought up on a hippy compound, a man who spent it seemed a large part of his life riding his motor cycle around the USA, taking any image that took his fancy. I on the other hand are the typical English middle class child, who rules are there to be obeyed and where travel is an unfortunate curse to be avoided at all costs. I doubt if we had ever met in person we would of had much to talk about.

But there was one common element and that was the dad's love of his daughters.

I first came across Wyatt's work when I was writing this blog entry At the time I was annoyed that society was  putting barriers in me recording my children's life. Wyatt had had similar issues, when he presented photos of his daughters that some labelled as obscene, rather than what they were,  the  recording of a child's innocence through the eyes of a father.

In an era where even a suggestion of impropriety to children can create something akin to mob rule these are dangerous territories and it would of been easy for him to turn away, but instead he did what many great artists do, and turned the issue on its head and used the controversy to examine how we deal and treat children in photography.

After that I kept an eye on his work, watching his twitter feed as he sent in photos from his travels (or notes from the road as he called them) and of his two muses, his daughters. As he did I came to admire his ability to present a story from, for me, an often alien landscape. I also loved the way he could get the expression and joy of how children are in your life.

You might have noticed that I have been typing this calling Wyatt in the past tense. That is because I was shocked to learn that Wyatt died recently after a brain aneurysm caused a motorcycle crash. You might say that he died as he lived, on the road, but I  doubt that is much consolation to his wife and daughter. Also in some way, his photos of his daughters gave me an insight into his life, which makes his passing feel so much more personal.

It is very hard to safe something consoling after a loss that does not sound trite or vacuous. This is doubly so when talking about a person who you only know through photos or tweets. Also I know it is highly unlikely that anyone of Wyatt's relatives and friends will ever read this obscure blog, but if they do, I would like for them to know how much his work affected me, despite our distance both  geographically and culturally, both as a photographer and a father, and in that small way he will live on.

R,I,P Wyatt Neumann Photographer and Father.

There is a fund for raising money for his Wife and daughters here