Reciprocity Failure

I don’t generally dwell on highly technical subjects in this blog, or rather I should say I haven’t done so for a while, but I am doing a bit of research for my current project and need to get this down somewhere where I can find it easily. I am certain I will forget most of the information I dug up on this subject within a few days so I am afraid I must bore you with it for the moment.

My current project involves exploring black & white pinhole photography. If you’ve been following this blog for any time you know I prefer color film in my pinhole cameras, usually Kodak Portra 400, and though this film is not immune to reciprocity failure I haven’t really had any problems with it, probably because my exposures rarely go longer than 20 to 25 seconds. My “go to” film for black and white photography however, is Tri-X and it is quite sensitive to reciprocity failure – thus my current quest for another black & white film, preferably with an ISO of 400.

In case you have no idea what I am talking about reciprocity failure is simply the tendency of some photographic films to become less sensitive to light the longer they are exposed to light. 

It seems odd that something specifically designed to be light sensitive should become less so simply by being exposed to it more but there it is. Like so many thing in life its just the way it is and we must learn to deal with it. Reciprocity failure is rarely a factor with exposures lasting less than a second but for longer exposures it can have significant impact. 

For instance a film with no reciprocity failure like Kodak BW400CN might require an exposure of 5 seconds in a given situation. A similar film with the same speed (ISO  400) that is subject to reciprocity failure like Kodak Tri-X or Ilford HP-5 will require an exposure of 15 to 20 seconds to properly capture the same image (this information was taken from the published data sheets for Kodak BW400CN, Tri-X and Ilford HP-5 films).  

In addition, reciprocity failure increases exponentially so that the longer the exposure the greater the failure. For example, an image requiring a 25 second exposure with the BW400CN will require an exposure of 150 seconds with Tri-X. This is a 5 times longer exposure for BW400CN but Tri-X requires an exposure 7.5 times longer for the same image. 

Since I generally prefer to shoot 400 ISO film in my pinholes I will focus on those films for now and offer the following notes:

Kodak Tri-X, 400 – If I understand the published technical publication data correctly Tri-X is fine down to about 1/10 of a second. At one second you should add one stop to your exposure. Beyond that it gets complicated and you should consult the technical data sheet (see link below) or just consider another film stock as I am doing.

http://www.kodak.com/global/en/professional/support/techPubs/f4017/f4017.pdf)

Kodak T-Max, 400 – This is an excellent film stock with good reciprocity characteristics. No adjustment is required down to 10 seconds exposure. At 10 seconds the technical data sheet recommends a 1/3 stop adjustment (why bother?) and at 100 seconds the recommended adjustment is only 1.5 stops. See link to technical data sheet below.

http://www.kodak.com/global/en/professional/support/techPubs/f4043/f4043.pdf

Kodak BW400CN, 400 – No problem! Apparently this black & white film develops in C-41, color processing just like color films and is immune to reciprocity failure for exposures up 120 seconds.  Beyond that you’re on your own to experiment and find out what works but here’s the technical data sheet below.

http://www.kodak.com/global/en/professional/support/techPubs/f4036/f4036.pdf

Ilford HP-2, 400 – This is a popular C-41 black & white film like the Kodak BW400CN but unlike that film, which has no reciprocity problems, Ilford HP-2 is similar to Tri-X in its susceptibility to reciprocity failure. See technical data sheet below.

http://www.ilfordphoto.com/Webfiles/201142711321939.pdf

Ilford HP-5, 400 – This very popular traditional black & white film is very similar to Tri-X and HP-2 in its susceptibility to reciprocity failure. See technical data sheet below.

http://www.ilfordphoto.com/Webfiles/20106281054152313.pdf

Ilford Delta 400 – Another black & white film similar to Tri-X, HP-2, and HP-5 in its susceptibility to reciprocity failure. See technical data sheet below.

http://www.ilfordphoto.com/Webfiles/2010628953322222.pdf

Fomapan 400 - Another black & white film similar to Tri-X, HP-2, HP-5, and Delta 400 in its susceptibility to reciprocity failure. See technical data sheet below.

http://www.fomausa.com/pdf/Fomapan_400.pdf

There are other 400 ISO black & white films available but I was unable to find any info on their reciprocity characteristics so I have omitted them for now. 

In conclusion, it seems that although Ilford and others have some very fine and popular emulsions if you’re worried about reciprocity failure you’re better off with Kodak. The T-Max and BW400CN both are very forgiving for exposures of up to about 2 minutes. Unfortunately the latter is only available in 35mm format but T-Max is available in medium and large formats.

I will update this information as I come up with additional data.

Oh, by the way, the image above was taken with my Olympus XA2 on Tri-X.

Love that Black & White

According to most sources the fastest growing (yes, I said growing) segment of the film market is black and white. I like color, especially some of the newer emulsions like Kodak Portra but there are some things you can only do with black & white film.

I know digital cameras have gotten pretty good at emulating black & white but there is something different and special about images from black & white film. Each film of course, has its own distinct characteristics and should be selected based on what effect you’re trying to achieve. If you also take the next logical step and print them using the traditional or what is called today “true” black & white process you end up with a truly unique, one-of-a-kind image that you can’t get any other way.

The image above was shot at night using the Olympus XA2, a fully automatic, zone focus, point & shoot from the 1980’s on my all-time favorite black & white film – Kodak Tri-X. The Olympus XA2 is fully automatic (except for the zone focus) with shutter speeds from 1/750 to 2 seconds and apertures from 3.5 to 14.

The two trees in the picture are right outside my office window and the light you see is from a “street type” light on a pole just to the left of the frame. The XA2 does not let you know what the selected settings are but considering the composition and lighting I must assume it was f3.5 at approximately 2 seconds.

Some things are just better in "real" black & white.

Breaking the Rules

I blogged about this before but I suppose it merits mentioning again, especially considering the photo above taken with the Pentax ZX-L  on CVS 400 color film. Shooting into the sun was something I was always told you’re not supposed to do. I remember all the Kodak film boxes that came with instructions on how to use your Kodak film and even the old camera manuals always that said to make sure the sun was behind you, “over your shoulder” when you took a picture! 

Of course, that’s just one of many “rules” we are free to break in the name of creativity. The point is, while rules are designed to generally give pleasing results in most situations, sometimes breaking the rules allows for dramatic effects that can also be pleasing.

In the photo above I was able to balance the back lighting enough to allow the beautiful color of the flowers to come through in contrast to the darker shadows and the bright streaks of green grass illuminated by the sun for what I consider a strikingly beautiful image.

…and of course, since I was shooting film I had no way of knowing what I would end up with for weeks until I finished the roll and had it processed and scanned.

I would like to say that I knew exactly what I was doing and how it would come out but the fact that I took several shots of this scene would indicate otherwise. I did however have a general idea of what effect I was going for the rest of was a combination of skill luck and faith – just one of the many things that keeps shooting with film exciting!

Pentax ZX-L

I just realized I have never really done a proper blog review of my “not-so-new-anymore” Pentax ZX-L. I got this camera back in early February and have been shooting pretty regularly with it. It has in fact become my “go to” 35mm SLR. I have mentioned it in a couple blog posts but never actually done a blog post on it so here I am to correct that oversight.

I can understand why I forgot to review this camera because like the ZX-7, the ZX-L just kind of came into my life and made itself at home like it had been there all along. There actually is very little difference between the ZX-L and the ZX-7, which I blogged about in my April 7^th, 2013 post, but those little differences are just enough to make the ZX-L my favorite. Not that I no longer like the ZX-7, quite the contrary. In fact the ZX-7 has a couple things I like better about it but overall I think the ZX-L definitely has the edge.

Like all of my Pentax cameras (except the ZX-30) all of my lenses will work on the ZX-L without the need for any kind of adapter. Even the old manual legacy lenses will work although obviously the onboard exposure computer cannot set the aperture or focus the lenses. That must be done manually.

Like the ZX-7, the ZX-L will offer a focus confirmation “beep” and LED indication in the viewfinder if you want it, and I almost always want it. One of the banes of my old age is that my vision isn’t quite what it once was making manual focusing a bit challenging at times. Like all AF systems it is not 100% but it is nice to have that confirmation beep or signal to give me a second opinion as to whether or not I have the image in focus.

The ZX-L has a 1/4000s shutter speed where the ZX-7 only goes up to 1/2000s. It also has P-TTL flash capability and a depth of field preview, both missing on the earlier ZX-7 but otherwise they are nearly identical so everything I said about the ZX-7 in my earlier blog post applies here as well.

The Sigma 28 to 80 macro-zoom that came on my ZX-L is a pleasure to use. I’ve never been much of a macro fan and the macro photos I have taken so far haven’t done much to amaze me but the lens is otherwise a good solid performer. I still prefer and want to get back to using my primes but I can see why the 28 to 80 zoom became the most widely used lens for the casual photographer in the final decade of 35mm film’s dominance.

The bottom line is I love everything about this camera which was one of the last 35mm SLR’s Pentax came out with. I can only imagine how great things might be for film shooters if digital hadn’t taken over when it did and they had kept improving and perfecting film technology.

Film is a Hobby. Film is Art.

Okay, film will never replace digital! Nor would I want it to. Digital photography is just so convenient and dare I say it, perfect for so many applications. 

I frequently have the need to document fabrication details, construction progress, or even damage with pictures as a part of my work in shipbuilding. I would never choose a film camera to do this although for many years I did it with film because that was all there was at the time. Now I keep a digital camera handy.

Family pictures at the grand kids’ birthday parties, ball games, graduations etc. – all done on digital. When asked to shoot portraits for the church directory I chose my digital camera. Why? Well, let’s see; the ability to see immediately whether you got the shot you wanted (with no blinking eyes or weird half smiles); no need for expensive film processing, and if you shoot in RAW and have any kind of decent software for post processing you can do all kinds of things with you digital file.

So where does that leave us with film and why are there so many people shooting film? After several years of shrinking film sales in the face of the digital revolution, Kodak is out of bankruptcy and most companies that remain in the film market report stable or increasing sales. These days film is a steadily growing market, especially black and white. 

There are a few professional photographers still using film but most film shooters today describe themselves as either hobbyists or artists. So as the digital dust settles it appears that what we have left in the world of film is a steadily growing number of amateur photographers and artists that appreciate the nuances of film and exploit it for their own artistic purposes and satisfaction.

Long obsolete, so called alternative film processes, such as cyanotypes, daguerrotypes and photogravure, as well as lith printing are also making a comeback. The film look has always been valued and appreciated in fact, it can be argues that most digital picture post processing efforts are attempts to imitate some aspect of film photography.

Since my own photographic interests do not include the mysteries and art of darkroom my own incursion into the hobby or art of film has turned instead towards the shooting part of the process and I have become enamored of pinhole photography recently. The photograph above was taken with a homemade cardboard pinhole camera shooting 35mm Kodak Ektar 100 for Worldwide Pinhole Photography Day 2012.

I have also started shooting a variety of specialty films available from The Film Photography Project (FPP) online store. This includes red scale, black & white movie film, and high speed traffic camera film. The FPP online store has become a film boutique offering more film stock s than were ever available when film was “king.” Each of these unique film stocks has its own “special effect” that digital folks would no doubt, love to emulate.

Ultimately I would like to combine the two and end up shooting some of these special film stocks in my pinhole cameras once I have mastered each separately to the point where I can predict and achieve the desired results.