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Archive 2004 · Focal Length usage.

dmcharg
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p.1 #1 · Focal Length usage.

Some stats i extracted from a sample of some of my images from the
past 18 months. This was just a sample from some trips during which
i used any of the following lens - 17-40, 35, 28-135, 70-200. Makes
me think -

Looks like i use either end of the 17-40.
Looks like i use either end of the 28-135.
Looks like i use either end of the 70-200.

The 35 is new so i didn't expect a large peak here. I sold the 28-135
a few months ago.

mmm do i really need zooms !

Focal Length = 17, Num pics = 867
Focal Length = 19, Num pics = 50
Focal Length = 20, Num pics = 28
Focal Length = 21, Num pics = 34
Focal Length = 22, Num pics = 34
Focal Length = 23, Num pics = 16
Focal Length = 24, Num pics = 27
Focal Length = 25, Num pics = 28
Focal Length = 26, Num pics = 21
Focal Length = 27, Num pics = 24
Focal Length = 28, Num pics = 808
Focal Length = 29, Num pics = 24
Focal Length = 30, Num pics = 77
Focal Length = 31, Num pics = 23
Focal Length = 32, Num pics = 40
Focal Length = 33, Num pics = 64
Focal Length = 34, Num pics = 13
Focal Length = 35, Num pics = 163
Focal Length = 36, Num pics = 21
Focal Length = 37, Num pics = 7
Focal Length = 38, Num pics = 25
Focal Length = 39, Num pics = 13
Focal Length = 40, Num pics = 221
Focal Length = 41, Num pics = 8
Focal Length = 44, Num pics = 19
Focal Length = 47, Num pics = 4
Focal Length = 50, Num pics = 4
Focal Length = 53, Num pics = 10
Focal Length = 56, Num pics = 8
Focal Length = 60, Num pics = 27
Focal Length = 65, Num pics = 12
Focal Length = 70, Num pics = 397
Focal Length = 73, Num pics = 27
Focal Length = 75, Num pics = 25
Focal Length = 78, Num pics = 24
Focal Length = 80, Num pics = 15
Focal Length = 81, Num pics = 27
Focal Length = 84, Num pics = 38
Focal Length = 85, Num pics = 15
Focal Length = 87, Num pics = 21
Focal Length = 90, Num pics = 11
Focal Length = 91, Num pics = 32
Focal Length = 94, Num pics = 29
Focal Length = 95, Num pics = 3
Focal Length = 98, Num pics = 31
Focal Length = 100, Num pics = 50
Focal Length = 104, Num pics = 43
Focal Length = 105, Num pics = 6
Focal Length = 109, Num pics = 52
Focal Length = 112, Num pics = 6
Focal Length = 113, Num pics = 37
Focal Length = 115, Num pics = 1
Focal Length = 117, Num pics = 3
Focal Length = 118, Num pics = 36
Focal Length = 120, Num pics = 2
Focal Length = 122, Num pics = 28
Focal Length = 125, Num pics = 2
Focal Length = 126, Num pics = 25
Focal Length = 127, Num pics = 4
Focal Length = 131, Num pics = 31
Focal Length = 132, Num pics = 3
Focal Length = 135, Num pics = 230
Focal Length = 140, Num pics = 41
Focal Length = 145, Num pics = 29
Focal Length = 149, Num pics = 24
Focal Length = 154, Num pics = 32
Focal Length = 159, Num pics = 33
Focal Length = 163, Num pics = 30
Focal Length = 168, Num pics = 12
Focal Length = 172, Num pics = 21
Focal Length = 176, Num pics = 35
Focal Length = 180, Num pics = 18
Focal Length = 184, Num pics = 25
Focal Length = 188, Num pics = 30
Focal Length = 200, Num pics = 343

Nov 13, 2004 at 10:56 PM

mjmetts
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p.1 #2 · Focal Length usage.

Interesting stats. They make a lot of sense though. How did you extract these?

On a separate note, not meaning to derail this topic, buy I noticed in your gallery that along with the awesome shots you have the Billingham Hadley (Large?). I'm considering this bag and I was wondering if you think it would be possible to put a small laptop (12" ibook) in it in addition to your gear. Maybe right behind the insert? Any thoughts on the general usefulness of the bag would be appreciated as well.

Nov 13, 2004 at 11:05 PM

dmcharg
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p.1 #3 · Focal Length usage.

Hi Michael,

I extracted these using a little program i wrote. I am a software engineer by trade
and was just playing and thought it would be very interesting to see what my
usage of the various focal lengths i have. Certainly makes me think. I need
to increase the sample size and sample all of my images.

Thanks for the comments on pics.

On the billingham. Well it really is a great bag and after buying about 5 other
bags i have finally found a solution that works for me. I was looking for a
walk around shoulder bag that would give me easy access to my kit whilst
on the move. I was looking for a bag capable of holding body + 3 lens
(one on the body + 2 additional ). In addition a big factor for me was the
ability to store the 10D with the 70-200F4 on the camera. I think you should
be able to get a thin laptop in there. Its expensive for a bag but for my needs
its perfect. The quality is very good and it really is very comfortable to wear.

Whats the full dimensions of your laptop and i will measure and see how it
would work ?

Cheers
David.

Nov 13, 2004 at 11:20 PM

Tai Mong
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p.1 #4 · Focal Length usage.

Nice compilation of data! I was thinking of doing the same with my pictures.

I'm guessing that the reason why the ends of the lens were used is because of the natural feel. By that, I mean it's awkward using the middle ranges, at least for me. Also, many times, I end up zooming with me feet when the lens cannot reach. This makes me wonder whether I really need zooms too. Thanks for the eye opening thought.

Nov 13, 2004 at 11:31 PM

dmcharg
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p.1 #5 · Focal Length usage.

I certainly have no intention of getting rid of my zooms i,e 17-40, 70-200F4.
If anything i will add primes at lengths where i have specific needs. I added
the 35 1.4 for low light stuff on the wide end and i may well add one of
85 1.8 or 135 F2 for the telephoto side. Best of both worlds i guess...zooms for
when i want max flexibility and primes for when i have specific needs....although
that 35 1.4 sure has spent much time on the camera since i got it. Given a
few months i will be very interested to see how these numbers look.

Cheers
David.

Nov 13, 2004 at 11:39 PM

mjmetts
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p.1 #6 · Focal Length usage.

Thanks David, I would really appreciate that. Here are the dimensions:

Height: 1.35 inches (3.42 cm)

Width: 11.2 inches (28.5 cm)

Depth: 9.06 inches (23.0 cm)

Thanks so much for the thoughts about it. It is quite expensive but I would rather have one good expensive bag than try 3 or 4 cheaper bags. It also seems to be about the perfect size/capacity for me.

Nov 13, 2004 at 11:46 PM

dmcharg
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p.1 #7 · Focal Length usage.

Hi Michael i just gave something a try. I took a book about the dimensions
you mentioned and it easily slides down the back of the bag. Just to be clear.
The billingham Large hadley actually comes with a full insert inside it that
is padded and this is the compartment inside which you store you camera kit.
The insert is what is padded. The bag is actually canvas and what i did for your
test was try sliding a book down between the insert and the outer canvas parts
of the bag and it fits without a problem. Just so you are aware the outer canvas
portions of the bag are not padded at all as i said above all padding comes from
the insert which is very nice.

I can send you a pic if you want tomorrow, Drop me an email offline.
[email protected]

Cheers
David.

Nov 14, 2004 at 12:11 AM

Jeff Donald
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p.1 #8 · Focal Length usage.

I don't mean to sound rude, I know you put a fair amount of effort in to your program and post. But I will gladly take one great shot at 115mm and trade it for all the mediocre shots at 17mm. I'm not trying to imply anything about the quality or type of shots you take, just that it's extremely hard to quantify art (photography) to numbers and statistics.

Nov 14, 2004 at 12:20 AM

dmcharg
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p.1 #9 · Focal Length usage.

Hi Jeff wasn't trying to put everything down to pure numbers i was just curious
about how i use my lens. A great image is a great image and i for one do not
really care what lens takes an image or whether it was a zoom or a prime or
whatever. Before i gathered some of this info i thought i shot alot more on the
long side but it would seem not. I do find i get a higher number of images i
like more on the telephoto side due to the ability to really isolate the subject.

My thought in doing this was much like something mentioned in Bryan
Petersons book on learning to see creatively. i.e take your images and
classify them accoriding to what you think the most important element of
the picture is i.e color, shape, contrast, texture and try to experiment in the
areas that you are weaker in. I also wanted to see how this correlated to
what focal lengths i most commonly use.

Cheers
David.

Nov 14, 2004 at 12:36 AM

gunblue
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p.1 #10 · Focal Length usage.

It's the quality not the quantity that counts. You may not be using the mid focal lenth of your zoom lenses much compared to both ends but you may have quite a number of keepers from those focal lengths.

Nov 14, 2004 at 05:00 AM

JohnLL
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p.1 #11 · Focal Length usage.

What file format does your program use for the images - RAW, JPG, whatever? Can you tell me where I can find the specs of these formats so I can write programs to do similar and different things?
In my own case, having only one body for now, I tend to go out with the lens I expect to use most, depending on the type of subject I expect to encounter. Being rather loath to change lenses too often in the field (laziness, risks of dust and clumsiness), I would guess that I also shoot a higher proportion of shots at the ends of the zoom ranges. But I do also shoot quite a few in the middle.

Nov 14, 2004 at 06:34 AM

StevenPA
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p.1 #12 · Focal Length usage.

Even if you do tend to use the "ends" of a zoom lens, having both ends is like having two primes, and presumably you'd have to switch between them all the time to go from, for example, 17 to 40, back to 17 again.

I've thought about this a lot as well: zoom vs. prime. For me zooms are flexible and practical, but primes are discreet and elicit great quality. So hard to decide...

Interesting program that satisfies that curiosity. Nice work! Any chance of making it available?

Nov 14, 2004 at 07:15 AM

Kyle Yates
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p.1 #13 · Focal Length usage.

mjmetts wrote:
Interesting stats. They make a lot of sense though. How did you extract these?

.

A lot of this info can be extracted from the EXIF --- but ensure you are using the right EXIF data as the EXIF standard has been updated a few times since its inception.

You might also have to extract the EXIF from the RAW data (there's usually an embedded jpeg in the RAW file which has this info in it).

One problem also is that some lenses do not report Subject Distance very accurately if at all and there are other odd errors that creep in.

For specs on the EXIF standard just do a Google search.

Programs like Breezebrowser extract this and I believe it's quite simple although I'm not a computer guru myself.

-K

Nov 14, 2004 at 07:59 AM

Azrael
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p.1 #14 · Focal Length usage.

Would be interested in this program too

Nov 14, 2004 at 10:04 AM

BrianP
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p.1 #15 · Focal Length usage.

Hi David:

It looks like you are a closet prime guy. You shoot probably 80% at the extremes of each lens.

If you ever put the program out for the public, let me know. It would be nice to have this as one simple program.

Nov 14, 2004 at 10:14 AM

stevei
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p.1 #16 · Focal Length usage.

Actually, what the stats say to me is that you could usefully use a zoom with a wider range, as it looks like you have a reluctance to swap lenses. Taking the peak at 70mm, for example. I find it very unlikely that 70mm is the optimal focal length for so many shots, compared to 75mm or 65mm, say, so I'm guessing that you're backing off with the 70-200 zoom as far as it will go, and that perhaps for some of those shots you might like to zoom out further, but you "make do" with 70mm to avoid changing lenses.

Similarly for the peak at 28mm, for example, it seems unlikely to me that 28mm would be the optimal point for so many shots. Perhaps an interesting analysis would be to add data on which lens it was, so when you shoot with the 17-40 on, do you have the same peak at 28, or is it only when you have the 28-135 on that the peak at 28 occurs? If the 28 peak doesn't occur when using the 17-40, this suggests to me that for a lot of the shots taken at 28 with the 28-135, you'd prefer to be able to zoom out wider. The same applies for the 70 peak, of course - does the 70 peak occur if you consider only shots taken with the 28-135?

Steve

Nov 14, 2004 at 10:43 AM

Jeff
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p.1 #17 · Focal Length usage.

stevei wrote:
Actually, what the stats say to me is that you could usefully use a zoom with a wider range, as it looks like you have a reluctance to swap lenses. Taking the peak at 70mm, for example. I find it very unlikely that 70mm is the optimal focal length for so many shots, compared to 75mm or 65mm, say, so I'm guessing that you're backing off with the 70-200 zoom as far as it will go, and that perhaps for some of those shots you might like to zoom out further, but you "make do" with 70mm to avoid changing...Show more →

Exactly. If you've ever taken statistics, you know that this this is not a 'representative' population from which you can draw any conclusions whatsoever, other than which lenses you tend to use most. The data is skewed heavily due to the physical zoom ranges of the lenses. It is interesting, however, and I did take the time to pull the data into Excel and graph it to see what it looked like. The graph clearly shows that the population ('n') is not representative (several severe 'spikes'), thus I didn't bother to post it. Posting the 28-135's data only would be a perfect illustration of this, as mentioned by Steve above. The best indicator would be daya from a 17-200/2.8L lens...

Fun stuff, though...

Nov 14, 2004 at 11:43 AM

nutek
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p.1 #18 · Focal Length usage.

I computed the statistics for mine some time ago when I only had one lens (the Tokina 24-200 superzoom) and I found similar results. The biggest spikes occur at the extremes, 24mm and 200mm, with intermediate spikes at 35mm, 50mm, and 135mm. I was very surprised back then that it corresponded so much to the primes' focal lengths, even though mine was on a 1.6x crop camera.

As Steve and Jeff pointed out, you are using two correlated factors (focal length and lens type) but comparing them across one common axis. It would be helpful to break the statistics down by lens, then compare usage count across different lens. E.g. compare usage count at 28mm on the 17-40 and 28mm on the 28-135.

Nov 14, 2004 at 02:10 PM

EB-1
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p.1 #19 · Focal Length usage.

I did a quick check on a week of shooting in September and generated the histogram chart above. Lenses were limited to 16-35, 24-70, 70-200, and 300 mm. The percentages at 300/420 were abnormally high for that type of work, but the 300/4 non-IS was new (to me) and I shot most scenes at multiple apertures.

EB

Nov 14, 2004 at 06:06 PM

CoolGeorge
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p.1 #20 · Focal Length usage.

The results that you are showing are exactly what I would expect they would be. I think that it is human nature to go to the end that is most appropriate for the shot you are looking for with the lens you are using. If the focal length is not enough, 8 times out of 10 you will still take the shot rather than change lenses, especially on the long end. You can always crop a bit. On the wide end, a few steps back is a lot easier than changing lenses, and especially so when you know that the majority of the shots to follow are going to mean changing that lens right back again. If you are talking a studio situation where the subject is known and isn't changing then get out the right prime and do it right.

Nov 14, 2004 at 07:04 PM

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