Xtol

I took this yesterday evening. The sun was catching the leaves in the Aspens whose leave had turned a wonderful bright yellow. Unfortunately there's a bit of what looks like (I hope¹) lens flare in the top of the trees on the right. I should have had a lens hood, but I have to figure something out when I've got the Cokin filters on the front of the lens (which is all the time).   

The pic was taken at about 4pm and developed by 5:15; by 7:30 it was scanned and spotted. Not only is this a bit more fun than waiting three weeks for Fuji to return the film (which they no longer do), but I like the results better. There is less grain, particularly in the sky. Since the film still Fuji Acros Neopan 100, the difference must be the developer (Xtol).

I will probably also try Eco-Pro which is supposed to be the same formulation.

¹ Because if it isn't lens flare it's a developing problem; and I'd rather it wasn't.

Home darkroom #3

My third darkroom is much like the second, but smaller. Certainly not enough room for the enlarger, but just about enough to mix the chemicals and shake the tank. There've been several "innovations" since the last time I developed any film. First, I now have a handy calculator to match time to temperature, film, and dilution. It makes the assumption that the relationship between temperature and time is a function of activation energy for whatever reaction is going on and that a log function is a reasonable approximation of the number of molecules with sufficient energy to take part int he reaction. The real answer involves integrating the area under a Boltzman distribution which I haven't yet been able to do. A quick look at the three films I just developed suggests it works.

The second innovation is not storing mixed developer. It's going to be easier to keep (I think) in power form, and mix only as much as I need just before processing the film. In order to do this I bought a jewellers scale.

Proper laboratory grade chemical balances start at about $850 for the most basic unit. Instead I found the little scale in the picture above for about $12, which was advertised as being accurate to one hundredth of a gram!  Just to make sure, I also bought two calibration weights and, astonishingly, the advertised spec was accurate (error < 0.01g).        

Another novelty are the measuring jugs - I was about to buy some Paterson measuring cylinders or similar, when I found these plastic measuring jugs at the Dollar Store. They are perfectly adequate for gauging the 12 fluid ounces the tank takes.       

The last innovation is Xtol, which according to Kodak delivers the second finest grain, the second most shadow detail and the highest actuance of all Kodak's developers. This looks like an unbeatable combination, and if it lives up to Kodak's marketing material, this will be my developer of choice. (I used to use D-76 which has been Kodak's workhorse developed for more than half a century. Xtol is apparently Kodak's latest - and its last - innovation in black and white film processing. 

The films is currently hanging up to dry. Apart from a few snafus (the clip covered some of the last frame, the first film was kinked and has a spot where the developed seems not to have reached the film),  not bad for my first film in over 10 years and my first roll of 6x7.

The next post, once the film is dry will report the results. Stay tuned.            

Replacing Walmart

Since the demise of the Fuji-Walmart service, I've been looking for another solution. I've found a small lab in San Jose near the university that will do both C41 and black and white. My first roll of color is ready tomorrow.  I've decided to go back to developing my own black and white. Tuolumne county runs a hazardous waster disposal program so I need to be able store the spent chemical for 3 to 4 months; but I think that's doable.  

End of the road

Got some disappointing news this afternoon. Fuji Labs, (to which WalMart sends 'odd' film like B&W 120) has discontinued its develop only service. The will still develop 120 but won't return the negs, which is completely pointless. So my cost per roll has suddenly gone from $2.33 to over $10. At $1 a frame I'm going to have to think twice about pressing the shutter; and digital is looking increasingly attractive...

So this excursion into medium format, which I had foolishly thought was going to be my preferred compromise between 35mm/digital and 4x5 for the foreseeable future, may well have come to a rather sudden end.

Now I have to decide whether to sell my Mamiya equipment or keep it for its (short-lived) nostalgia value.    

Good glass

I was wondering today whether it was worth spending lots of money on good lenses. I know that's the conventional wisdom, but I've gotten on fine not buying DeWalt tools for the workshop, so why buy a Rolls Royce of a lens? Is it overkill?

A moment's reflection suggested not. I really don't notice having good glass. But I did with my little digital - a Nikon Coolpix S2200 which got very fuzzy in the corners. And my epiphany was this; it's not noticing that is the hallmark of quality glass. If the glass were poor, as it is on the Coolpix, I would (and indeed did) notice, and not noticing is a testament to a good lens. It's one less thing to get in the way.   

Counter-intuitive

I had settled on scanning my negatives at 2400 dpi because, starting at lower resolutions and working upwards, that was where the grain became noticeable. Any higher resolution, I reasoned, would only make the grains larger and not reveal any more detail. I was wrong.

There seems to be an 'interaction' between the scan resolution and the grain size when the two are close which actually produces a more pronounced appearance of graininess. At higher resolutions, though the grain is still visible, it is less distracting.  Here are some examples:

2400 dpi

3200 dpi

4800 dpi

6400 dpi

9600 dpi

Surprisingly, the least grainy in appearance is the last scan at 9600 dpi (which is a shame since it takes between 7 and 8 minutes per negative at this resolution).  So it looks like I'll just have to learn to be patient.        

Finding Gamma

Really, this is a note to remind me that, based on my empirical testing, for low values of gamma, the gamma value at the scanner and the gamma value in GIMP are additive, and sum to about 3.2. (This puts Zone 5 at a digital (linear) value of 127 out of 255.

There's probably a mathematical proof of this, but I'm not going to try to derive the result. Suffice it to say that I will now start using scans with a gamma of root 2 and then add 1.8 in GIMP. This is just a mnemonic device; root 2 is common and 1.8 is the typical display gamma.

Neither value has any substantive significance here. However, given the odd things the Epson software does with the tone curve and the top and the tow, I decided not ti use a gamma over 1.5 at the scanner. I also don't want to have GIMP to all the rescaling since I think this is best done at nearest the source in the hope that it's achieved in the AD converter, and not afterwards.

Acros 100 dynamic range test

Procedure

I metered a fairly flat (in terms of contrast) wood panel (the garage wall). I then exposed 8 frames each one stop greater than the last, starting from the metered exposure. This represents zones 5 through 12 (5,6,7,8,9,10,11, and 12). With a second roll I did the same, but stopping down, giving me zones 5 though -2 (5,4,3,2,1,0, -1 and -2). Development was normal (no push / pull), courtesy of Fuji Labs and Walmart.

Results

The results were interesting. Ansel Adams talks about Zones 0 and 10 as the points at which detail can no longer be resolved: but film evidently has improved. Acros 100 has a very broad dynamic range, with detail discernable in zones -2 and 12!

This composite shows the negatives from zones 10, 11 and 12 and 0, -1 and -2 and some others (1,2,8 and 9) thrown in for good measure. This was scanned such that the dynamic range on the 'input side' was from 40 to 248, values measured individual negatives as being the 'metered' values for -2 and 12 respectively.

      
Compare this to Ansel Adam's Fig 4-3 on page 50 of The Negative; in Adam's figure detail is resolved in 8 zones (from 1 to 9 inclusive). Here, detail can be discerned in zones -1 and 12 (there is some in -2 in the top right but it's a little hard to make out. The dynamic range of Fuji's Acros 100 is comfortably 13 stops. Looking at Zone 12 suggests that there is considerable scope for further over-exposure, perhaps another 2 stops. 

This compares rather favorably with two recent digital cameras, the Olympus OM-D and the Nikon D800. Their dynamic ranges are shown in the chart below taken from dpreview's measurements. The D800's range is only 11 stops.

Conclusion

This gives both the flexibility to get the exposure wrong and still recover the image and, if the negative is properly exposed, the ability to resolve enormous range of light levels. It also provides huge flexibility in creating the final image since there is so much information on the negative with which to work. 

The resolution at the over exposed end (11, 12) seems better than at the other end (-1 , -2), so my inclination is to over-expose by a stop (in other words rate the film at 50 rather than 100). 

P.S. Exactly 30 years ago, I listened to arguments about the merits of the CD over the vinyl LP.  Analog proponents (and I'm still one having never gotten rid of my Linn LP12)  asserted that a good turntable / tone arm could resolve greater dynamic range than could be digitally encoded in the CD; detail in the quiet passages and in the loud ones was superior on vinly with a good setup. This was sufficiently important to make up for the pops and scratches. Film seems analogous; the greater dynamic range over the dust and debris (no discernible grain if the format is large enough). And with some digital spotting, even the pops and scratches, dust and debris can be removed. Looks like analog has some life left in it yet...

Inverse square law

I'm beginning to learn some basics of lighting. So this may well be wrong, but the physicist in me couldn't help itself.

Several of the lectures I've listened talked about the inverse square law. The problem is, it doesn't apply: or at least not strictly to the problem they describe.

The inverse square law models a point light source radiating uniformly in all directions. At a distance x from the source, the energy falling on an area y is the proportion of the power of the source of area y relative to the surface area of the sphere of radius x.

If you double the distance from the source, the surface area of the sphere at 2x is now four times as large (A=4/3Πr²) since surface area increases in r². So y is now 1/4 of the area of the larger sphere and so receives only only 1/4 of the energy emitted by the source.

But often the lighting being used and measured in the studio isn't from a point source; it's collimated with umbrella reflectors, so the energy doesn't fall off as the square of the distance. The ultimate in collimated sources is a laser; absent scattering all the energy emitter at the source hits the target. The same principle applies to theatre spot lights or search slights.  

That being said, I am guessing that for soft boxes the inverse square law is a fairly good approximation since each point on the front of the box might be considered as a point source. But in any setup in which light from the source is focused, the inverse square law won't apply.

Disintermdiation

This post probably doesn't belong here, since it's really about digital: specifically my prediction that the Internet will render prints obsolete, and with them the need for mass market dedicated cameras. Aside from some niche uses, most people will take pictures on their smart phones, and upload them directly to a website, such as Facebook, where they will be viewed; the images will never be printed from beginning (capture) to end (viewing). Smart phones are better positioned to do this than cameras since they are already connected to the net. If the highest resolution needed is that needed to view a picture on a large screen TV, then a 20+ MP dedicated camera looses out to an 8MP smart phone. I give the mass market segment of the dedicated camera industry another 10 years.   

Reducing the number of variables

For the moment I have decided to scan all my black and white negatives with a simple rule. Turning off the scanner software's auto exposure, the bottom of the histogram will be 0 and the top 255, with an gamma of 1.25 and the tone curve set to linear.

This allows me to 1) reduce the number of variables so that I can learn more easily the effects of manipulation in GIMP, and 2) should, in theory, be a more constant, predictable and and perhaps accurate representation of the characteristics of the film itself.

Another comparison

A small portion of the same scene.

First the LX3:

then the RZ:

Colour printing

I'm glad I'm not printing this in the darkroom: I've tried over 20 variation of the scan settings, which, if this were colour paper, would have cost a small fortune. I'd have been ducking in and out of the darkroom to see what I'd done, and since it takes a while for my eyes to adjust, this takes time and introduces error. I also couldn't have been writing this at the same time as the print was developing (the scanner is scanning at the moment).

Here are the thumbnails of some of the variants. The differences between them are generated, in some cases, by very small changes in the scan settings (e.g., from 236 to 237 in one of the blue channel parameters).  In just one panel - the AD coding 'histogram', there are 5 settings per channel, so there are a lot of variables to mess with.     


This is the final product. It probably has slightly more blue in the highlights than the original scene, at least as I remember it (it was late evening as the sun was setting and the light was fairly yellow), but it seemed more pleasing to me than a possibly more accurate representation.

Fuji Reala 100

Two rolls of color negative film came back today. It's much harder to work with than black & white because the film itself is so dense which means the information is compressed into a much smaller range. That makes the tonal gradation rougher and reduces the margin of error. This is visible in the 'sudden' transitions between adjacent tones. Here is a comparison with my LX-3.  First, LX3 image:

Next the film version (Fuji Reala 100).

I'm not too happy about either image to be honest. The lower one seems to me to have a little to much cyan, while the upper is a shade too yellow. The lower image could also be a little flatter. But this was my first attempt and it's much harder than black and white - obviously - since there are many more variables. But this is all about learning the craft. The road is long, but the path is clear (sounds like a quote but Google won't tell me whose).

P.S. Seems I left the white balance setting on the LX3 to "house with shadow", which according to the user's manual is for "when taking pictures outdoors in the shade", which wasn't the case here. So the odd tint in the LX3 is my fault. More tests (and care) are clearly warranted. 

Digital Analog(Digital) Comparison

Two images of the same scene. The top one was take with my Lumix LX3, the lower image with the RZ-67 and Acros 100.

The film was scanned at 1200 dpi which gives it about the same sized file and resolution as the digital end-to-end below.

Putting the 'S' in

The Epson V700's software produces what appear at a glance to be good 'exposures' when set on automatic, but on closer inspection have some serious problems. The highlights are very flat and often blown out and shadows compressed to oblivion. This means doing the A-D mapping from emulsion to bits by hand.

Without intervention, the scanner uses a logarithmic function for reading negatives. The result over emphasizes shadow and highlight detail while compressing the mid tones (see below).

Straight from the scanner

While all the information is here, the balance between the mid gradients and the ends (light and dark) doesn't look right so some tweaking of tone curve is needed. The mid tones need separating and this generally means squashing the highlights and the shadows, making an 'S' curve (or something like a cumulative normal distribution).     

In the first, the contrast in the sky is flattened and a little in the shadows too, while the the tree trunks are opened up.

    
Here's another interpretation of the image, a little more somber. The shadow detail is still preserved but the tree on the left in the sun is darker. The sky also retains slightly more contrast. This comes at the expense of the mid tone separation.

Whether the sky was or should be portrayed as that dramatic is a choice. The upper picture emphasizes the light on the tree on the right which was caught when the clouds opened temporarily. The lower one has more texture and a more threatening sky. I think my preference is for this last one.   

I'd probably crop some of the sky if I were printing this, (not least because of the streaking at the top which I think was from lack of agitation in processing). 6x7 is squarer than 8x10, and some cropping would be expected, but the slightly unusual squareness has an odd appeal. Perhaps that's just because it's late and I'm tired.     

My light meter

I am still debating whether I should take my Honeywell Pentax spot meter with me. The answer is probably yes but for the moment I've been using my trusty Lumix LX3 as a meter. Since I take it with me everywhere, and the results are fine, it's one less thing to carry. This means  giving up the whole idea of pre-visualization and zone placing and relying to some extent on the latitude of the film and 'post processing'. But since I'm moving away from the zone system which 1) I never mastered and 2) is largely about properties of emulsion and chemical film developing which I no longer do, this may not be too much of a problem. We shall see.     

Fuji Acros 100

The second roll of Fuji Acros 100 wasn't plagued by the developing problems of the first one, and the results are fairly pleasing. The grain seems less pronounced then Delta 100. It's also much cheaper so I think this will be my slow black and white film. Next I'll try pushing it at 200ASA.  

A bump in the road

Some quality control issues at Fujilabs? There is a dark band on the left which looks like the tank wasn't agitated during development. I may have to go back to doing my own developing - if I can figure out some means of disposing of the chemicals.

Ilford Delta 100

Ilford was the film I grew up with. Somewhat iconic, the byword for black and white. This isn't FP4, which I used in my teens, but Delta 100, slightly slower but, according to several posts on flickr and B&H's blurb, with finer grain.    

Three exposures: the first is metered on the nose, the second one stop under and the last one over. Each was scanned with the input limits set to the extreme ends of the histogram and the toes set to smooth, 30 in the shadow and 225 for the highlights. Gamma was 1.5 for all three. Resolution was 1200dpi. A little may be gained by going to 2400dpi, but the scan time is much faster.

On the nose

One stop under

One stop over

At these settings, the last is clearly not working. I like the first two, so the experiment suggests that these settings work and I might use Delta 100 at 125ASA.

The almond trees, which bloomed in late February this year, are just outside Oakdale, CA.

Wot? Another blog?

Well, yes. This one is devoted to my experiments in scanning 6x7 RZ negatives.

I'm going to be trying out several films, all developed using Wal-Mart's send out processing service and an Epson V700 scanner.

It's also a kind of shared memory. I could write this all down and keep it in a booklet in my desk draw, but the work involved would be much the same as posting and here someone one might find something of interest / use.