Calibration

Most of the work I've been doing recently is about process standardization and reproducibility (quality in the operations management lexicon). Last year I systematized the time/temperature calculation creating a web-based app that uses data on the film, developer, dilution and temperature to calculate  the appropriate development time. Hit and miss is (thankfully) a thing of the past. More recently I've been focusing on calibrating the film, much as one calibrates a display or a printer.

Each emulsion responds to light in a unique way. Thankfully Kodak's process control is such that I haven't yet found differences between batches (although I'm not sure the films I've shot weren't actually from the same batch).

To begin I create a negative with bands of different exposure raging from seven stops under exposed to seven stops over. This is about the dynamic range of TMX-100. I develop the film and scan it with a linear tone curve, setting the black and white ends of the output to the darkest and lightest bands on the negative.

I then use GIMP to measure the level of grey the scan has generated for each level of illumination on the negative. From this I generate a series of tone curves (49 in all) for different ranges of emulsion density to compensate for the emulsion's characteristics at different exposures.

For example, one curve might correspond to a negative in which the shadows were 3 stops below middle gray and the highlights 5 stops above middle gray. Rather than labeling them in stops over and under, I label each curve for the range of measured emulsion densities. So in this example, the tone curve would be the one that captures emulsion densities from 143 to 232. (These are all out of 255, the 8 bit tonal representation in the digital image).Doing so allows me to choose the appropriate curve simply by looking at the histogram of the each negative.

TMX-100 measurements

The red line on the chart on the right shows the density of the TMX-100 emulsion for different EV levels. The response is clearly non-linear. At light levels above middle gray, (EV>0) there are only small differences in density; at low light levels the differences in density increase at each step until 5 stops under when they decline sharply.

This suggests first that underexposed areas, the shadows, will be hard to deal with unless the response curve is exactly matched to the exposure; and it reenforces the dictum - "expose for the shadows, develop for the highlights", which helps ensure one doesn't have to deal with the non-linear behavior of the emulsion for very low light levels (-5 EV and below).

The curved blue line shows the intensity of the scanned image for each exposure level. Because the negative was scanned with a gamma of 1.5 the line curves upwards rather than being straight.

Using Microsoft Excel, the tone curves are written into directly into the Windows registry keys for the Epson scanner; when the scanning software is opened the tone curve drop-down box is populated with the generated tone curves. Using them is fairly simple. Looking at the histogram for each negative, the levels for the darkest and lightest points are determined - since each tone curve covers a different range of emulsion densities this measurement determines which generated tone curve to use.

Atlantis

A quick trip to Florida last week afforded the opportunity to spend a few fascinating and nostalgic hours at the Kennedy Space Center. The star attraction is the Atlantis orbiter, around which NASA has built a fascinating exhibition.

Atlantis (I)

To be within a few feet of the Space Shuttle, the searing heat of re-entry clearly visible in the charred insulating tiles on the nose, was for someone who grew up with the Apollo program, an indescribable experience. 

Atlantis (II)

For some reason I can't explain I was moved almost to tears; three days later I am still left completely awestruck by the monumental achievement of America's space program; and saddened that today we no longer have such lofty goals. 

Printing (3D)

My 4x5 tank takes 54 fl oz, a bit much if I only want to develop one or two negatives. You can't partially fill the tank because the negatives stand upright. So I decided to try and design a negative holder that would fit in flat at the bottom of the tank.

This is the design. The  bracing struts are hollowed out to reduce the amount of material used (which quickly gets expensive).

The carriers are stack-able and the gaps in the sides are supposed to let the chemicals flow easily into the carrier and over the negative.

The design was created in Sketchup . Using the STL export plugin I created an STL file which I uploaded to Shapeways, a 3D-printing service. I chose the cheapest material (white flexible plastic).

This is the finished tray (actually two stacked together).

The good news is that the plastic isn't affected by developer or fixer. There are however some improvements I'm going to make. There probably isn't enough flow over the negatives - the negative that was in the lower carrier was spotty in places. And the slides are a little thin.

The cost per carrier was $11.55. A much more solid version will come in at $19.04 and I have a design somewhere between the two, with similar sides but stronger bracing ($14.06).

It's not a particularly cheap solution and it will take quite a while to pay for itself in saved developer, but it was an interesting exercise in creating something useful.

TMX100 vs LX7

Here I compare the same scenes taken with the Nikon F5 using TMX 100 developed in Xtol and my Lumix LX7. It's not the whole roll but gives one some idea. The metering on the F5 is very good.

TMX100	LX7

Power to weight ratios

The Nikon F5 is a fairly heavy camera, so I began to wonder about the ratio of pixels to weight. Here are the results.  

Camera	Weight	Image size	MP / lb
Lumix LX7	10oz	10MP	16MP/lb
Mamiya RZ (110mm f2.8)	5lb 9oz1	26MP3	4.7MP/lb
Olympus OM2-SP (50mm f1.4)	1lb 15oz	8MP4	3.5MP/lb
Cambo 45SR (180mm f5.6)	24lb2	52MP5	2.2MP/lb
Nikon F5 (24-85mm f4.5)	4lb 6oz	8MP4	1.5MP/lb

1 - Includes the LX7 in lieu of a light meter. Does not include tripod.
2 - Includes tripod, but not case or extra film.
3 - Scanned at 2000dpi.
4 - Scanned at 3200dpi.
5 - Scanned at 1800dpi.

So it turns out that the Nikon has the lowest power to weight ratio, lower than the Cambo SR! The Mamiya does well (though with a tripod it comes out no better than the Olympus).

Middle age

There comes a point where one has to come to terms with a shift in perspective, a sea-change in motivations.

This is it.

Last week, I bought an Nikon F5 and a Nikkor 24-85mm AF VR zoom. I mention the letters... well I'll come back to that. In my defense, I paid less in inflation adjusted dollars than I did for my Olympus OM-1n in 1980¹. And I didn't even have a job then...

It gradually dawned on me that I have no real photographic use for the camera. I don't shoot much 35mm; if I want good images, I have 4x5 for really big files, and 6x7 if I want quality with something I can walk around with. 35mm delivers less in terms of resolution than my 10MP Lumix LX7 (which I really like). I don't need 8 frames per second (which translates to $4.50 worth of TMX100 in three seconds) or 1/8000^th of a second shutter speed; I can even work a rewind lever; you can do it quite easy
If you have any strength in your thumb.

While I do enjoy the process of developing film, that's mostly nostalgia and comes with a penalty; digitally spotting the negatives, which is not that much less tedious than doing it with a paint brush - as on many an evening I watched Derek doing years ago. Anyway, I've already got two very nice and easy-to-use Olympus OM-SP2s that I've had for years were I really going to go back to shooting 35mm. Given that film is getting more and more expensive, I began to wonder what on earth I'd done (or more precisely why I'd done it).

The only reason one is left with that isn't self-justifying post-hoc rationalization is that I'm buying as a collector rather than a photographer. I've always had a bit of a hankering for the F2. I nearly bought one ten years ago at auction (though in hindsight I'm quite glad I didn't). And the F5 I found is a very nice example of Nikon's last heavy duty film camera; not a mark on it. It's got a host of features that presage the flexibility of digital cameras (most of which I probably won't ever use). My MO, where available, is almost always aperture priority, even on the LX7 so P and S aren't of much interest, though M I will need for flash. Double exposure I did and got bored with 30 years ago. I'm too cheap to bracket, and I don't want to spend $240 on a card reader to get the EXIF data out of the camera, though I would if I could find a cheaper way of doing it.

There are some things though, that my older 35mm equipment doesn't have and these may lead me to pick up this camera to take pictures. First, the auto-focus appears to be very precise and while I'm not too lazy to turn the focusing ring by hand, it does mean one thing less to have to do before pressing the button; much more point-and-shoot-like. And it's extremely fast so I don't miss the shot with a moving subject while trying to keep it in focus. That the AF piece.

The other is VR. The only vibration reduction device I've used on a film camera is a tripod. Though I've not yet run a roll through the camera (the lens only arrived today) it's going to allow me to use slower, finer grained film. My current preference is for TMX 100.

Some other nice touches on the body are the built in winder, the automatic setting of the film speed (no more "duh! I forgot to change the ASA"), really easy film loading, a little window in the back so that you can see the film canister that's actually in the camera (avoiding having to stick ends to film cartons into the slot on the back), and a very comprehensive digital display in the viewfinder. All in all it's a very well thought out camera with lots of touches to make ones life easier.

One thing that did surprise me is that the viewfinder is much smaller than the OM-SP2 or the FE. Clearly a design decision was taken somewhere that you had to move your eye too much to take in the entire filed so viewfinder have gotten smaller. I'm not sure I like the smaller viewfinder but we'll see.

I want to pay tribute to Nikon's designers and management for the attention they paid to backwards compatibility. It would have been easy (and almost certainly cheaper) to build new products that weren't constrained by earlier design choices. But starting with the transition to AI lenses in the 1970s, allowing users to preserve their investment in lenses when upgrading bodies and vice-versa, this was, and clearly still is, a central design tenet (and one by the way that IBM didn't understand until it cancelled the FS project at the 11th hour).  So the 24-85mm lens that Nikon only announced in June last year works perfectly on a body the company stopped making nearly 10 years ago. The other side of the coin is that Nikon's design and engineering teams must have had a very long product road map and designed current products with future ones in mind.  In this day and age of built in obsolescence, disposable products and computer software which won't work on last years operating system, that's something to which I think we've become quite unaccustomed.

So although this is really more of a collectible that a tool, for a while at least, it may be my nearest film based alternative to the LX7 (though it's clearly not quite convenient or discrete).

1. I paid £125 for my OM-1n, which I bought used in 1980 from Fox Talbot in Hammersmith. Adjusting for inflation and exchange rates, that's between $644 and $846, depending on whether you apply UK inflation to the pound and then do the exchange at today's rates, or do the exchange at 1980 rates and then apply US inflation. Averaging the two gives $746, more than the $715 I paid in total for a 'new (other)' lens on eBay and an E+ used body from Adorama.

TMAX 100

When my Nikon FE arrived I wanted to put a roll through quickly to make sure the meter and shutter worked properly.  I had lots of rolls of Kodak Gold 200 so I shot a roll of 24 exposures. Since CVS got rid of their film processing last year, I took it down to Walmart (3 more miles, round trip); only to find it too no longer develops on the premises. Inevitable I know, but a shame none the less. I can only hope that film finds the same roll as vinyl; an old technology that comes back in to fashion.

So I needed to do some B&W that I could develop myself. In 35mm, I had some FP4, a roll of Kentmere 100 and two rolls of TMAX 100 that Russell Kord kindly gave 20 years ago. So I put in the the TMAX, which I'd never used before, and these are some of the results.

The top two images both have bits of sky which is where film grain tends to be most conspicuous. The clips on the right of each illustrate how little grain TMAX has. Of course, without a yellow filter, the sky is quite white and grain may be more apparent when it's darkened with a filter. But it's pretty encouraging nonetheless, and seems to be considerably better here than Fuji Neopan. More tests are in order.    

As a footnote, I'm astounded that the film was still good after 20 years of being carted around (and not kept in a temperate controlled cellar).