2014-05-20

How to estimate SLR production numbers

Only a few camera producers have published production numbers of their SLR cameras, for the majority of the others we have to rely on other techniques to assess this interesting figure. One of the most often used methods is to simply look at the serial numbers of a certain model and to find the respective lowest and highest known numbers. The difference of the two is supposed to be the number of produced units. I guess most numbers you can find on the internet are based on this simple estimate. Unfortunately, these numbers get copied and pasted into new sites and the more they are repeated people tend to believe they are true. 
To really find out the highest (or lowest) serial number produced one have to look at many, many units. Fortunately, today there are e-bay sellers posting pictures of the cameras and in many cases you can find the serial numbers quite easily. In the following section I will present a slightly different and in my eyes more accurate method to estimate the production number of a certain camera model. 

The "Average Distance Analysis Method"

1) Get as many serial numbers as you can get (number = n). The method already works with a few, let's say n=5. However, the bigger the basis the more reliable and accurate the result. For the most time I stopped looking at about n=50, when I realized that the final result was not changing anymore.
2) Sort the numbers in ascending order and for the sake of visualization plot them using a spreadsheet programm like Excel. See above graph. A spreadsheet software is also very useful to do all the maths and automate the effort. 
3) Get the difference ("Distance" = D ) between all neighboring serial numbers and calculate their average (ØD).
4) Look for larger production breaks (red lines in above graph), number of these is B. I actually used this rule of thumb: If this particular distance D is more then three times larger than the average ØD I called it a break. However, you can easily see them in the graph.
5) Eliminate the break distances from the average calculation (important!)
6) The formula for the estimated production number P is...

P = ØD × (1 + n + B)

Here is my example for the Nikon FM: I got n=54 serial numbers from ebay. The lowest was 2117708, according to this web site they start wit 2100000. The highest was 3460001, the difference between both is 1.34 million. Plotting the graph one can easily see that production stopped at # 262xxxx and resumed at # 3xxxxxx. The gap was about 390,000 units. The average distance I calculated was ØD=18,315 units. Putting that into the formula results a total of 1,025,643 units.

This method works provided the following preconditions: 1) The serial numbers used are randomly picked, which is normally the case for e-bay auctions. 2) They are evenly distributed over the entire production period and they did not change the rules of numbering. For example, they could have started using odd numbers for a different model. Not very likely, though.  3) Production breaks or production in number blocks (and not using all blocks) is a relative common theme. This is not a big issue as this can be addressed by the method. However, the more breaks there are the more known serial numbers are needed to make it accurate.

The biggest advantage of this method over the highest/lowest method is that with ØD you get at least a very good estimate what number you might have to add to the highest known to get to the "real" last number made. You can verify your method with the low end. Take the lowest serial you've seen and substract ØD. What you get should be close to the round number one is expecting. In my case this is pretty good: 2117708 - 18315 is only 607 units off the reported start line.

I'd like to invite everybody to try it by yourself. I would offer to send you an Excel template sheet, where you just need to enter the serial numbers (send me an e-mail). Or just leave your comments below, what do you think about the method. I will keep using it for my further assessment of the historical Japanese SLR market.

2 comments:

  1. Can you tell me how you calculated the F and F2 numbers?

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    1. For the F and F2 numbers I totally relied on the general information given from multiple sources in the internet (e.g. Wikipedia). However, the numbers fit with the serial # table given here (http://www.destoutz.ch/typ_production_data_f2.html). So I used this to distribute the numbers over the years.

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