BHC Loc: Strawberry Valley, JF, USA

I do not have an Engineering Degree, but have been told by a PhD in Mechanical Engineering that the vast number of variables in generating and applying steam power make accurate measurement impractical. We are able to estimate horsepower based on Tractive Force (124,300 lbs) on our 4-8-8-2 AC12 locomotive. It apparently takes four 1500 hp F7A Diesel Electrics to pull the same load as the AC12, leading us to estimate 6000 hp. Inasmuch as we used up to three AC12's to haul loads over Donner Pass and the earliest 1000 hp DE's required 12-15 units, we are comfortable with our estimate, but have no way to actually measure the horsepower. As our Cab Forward AC12 is no longer operable and is the only one remaining in the world, we'll probably never really know for sure. Surprisingly, calculation of the Tractive Force is rather simple.

35B Loc: Australia

Hi darkroom 317,
many thanks for the links, just going to eat now, I will explore them later.
Thanks again,
35B.

Michael Hartley Loc: Deer Capital of Georgia

Anything, can be 'overthunked'.

selmslie Loc: Fernandina Beach, FL, USA

CMS 20 presents a couple of difficulties for ordinary photography. I had to shoot it at ISO 8 and needed to use compensating development to control the highlights.

I found it impossible to detect the grain when I scanned it at 4000 dpi. I would be surprised if a 7000 dpi scan would reveal the grain either.

Of course we are comparing apples to oranges. CMS 20 is a B&W film. Color film does not come close to B&W. On the other hand, cameras with a Bayer array don't really produce the resolution that they imply either. A 36 MP sensor actually delivers only about 18 MP of resolution after processing the colors from the Bayer array. The Leica Monochrom or Sigma Foveon sensors do not have this issue. The 24 MP Leica should be competitive with a conventional 48 MP camera and the 19.5 MP Foveon should do as well as a 39 MP color camera.

This highlights the futility of the megapixel race. There simply are no affordable prime lenses for the 24x36 format that can resolve detail at such high levels. If you get past 100 lp/mm you have to be using an exceptional lens and meticulous technique. That resolution will probably only happen near the center of the lens when it is stopped down considerably.

Given the lenses that most of us can afford for the 24x36 mm format, the limiting factor is neither the film resolution nor the megapixels.

On the other hand, 50-60 lp/mm is about what I can get with my Hasselblad lenses. Combine that with a format that is about 57 mm square and you get better resolution than ordinary full frame, regardless of the number of megapixels.

Retina Loc: Near Charleston,SC

You mention apples and oranges. I will add pears. I used to work with Kodalith on a copy stand with a 55mm Micro-Nikkor metering TTL at ASA 3 and then developing under red light to reduce highlight blockup. It was not continuous tone, but I could get half-tone printed photos to appear on enlargement to be continuous tone. It did require careful attention to technique for all the factors I could think of at the time. I was impressed with what a good fixed length macro lens could do with a well made camera. I was just a college student on a $2/hr work-study job but the fun made up for the low pay.

Kuzano

Everything related to the scan type and quality with regard to this question.

The scan is the biggest loss from film to digital in this process. The range of quality from the lowest flat bed scanner to Drum scans from a pro lab, are vastly different with regard to quality and megapixels returned.

A bit off on language here, but a sensor capture in a camera might be considered 1st generation for RAW, 2nd Generation for a camera Jpeg, and second or third generation for a scan of film or neg/transparency. Again, not sure if that is appropriate language. But scanning film (print, neg, or transparency) is somewhat after the fact and loses in the translation.

Now, you can make that up somewhat with larger film like medium and large format. However, you always lose in the scanning process, and "miniature" film like 35mm is a real compromise to scan.

Kuzano

Well put, and I believe the difference between film and digital is the reason some say "I can tell the difference". It's subtle but it's there.

I don't get too technical when I think and talk about these things. People talk about a technically perfect image, and then someone goes out and breaks all the technical rules and brings back a technically unsound that knocks you on your ASS.

Technical proficiency may be the overall best way to shoot, but I love the surprises that happen when you just glaze over and get a stupendous result. Those are the shots I would love to be able to get 99% of the time.

Not gonna happen, however!

K2KImages

Image sensor resolution is not based on ISO. Resolution is how much detail a sensor can have. Typically a higher MP sensor (36mp) will have more detail. ISO is how sensitive the sensor (pixels) are to the light. Higher ISO will introduce noise, not a indication of resolution. If you need more info Google "film or digital resolution" and "ISO photography". Hope this helps.

burkphoto Loc: High Point, NC

Well, I agree, except to mention that metadata is a wonderful thing when it comes to "repeating happy accidents."