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February 18, 2004
Some more face-to-face learning experiences

More personal recollections, in a way that reinforces this theme (which I also bounced over to Transport Blog), namely why face-to-face contact makes learning things so much easier, and hence why travelling is still such a worthwhile activity, despite all this new gadgetry we now have, much of it of the sort which you might think would make travelling superfluous.

patrick.jpgThis evening I managed to entice Transport Blog supremo Patrick Crozier over to visit me, to explain about how to embed thumbnail pictures in postings. I hope very soon to be concocting a posting for Transport Blog, with lots of thumbnail pictures, which will make use of this knowledge.

Patrick had threatened to email me with the instructions for doing this, but I am extremely glad that instead he was able to call round in person.

There were about half a dozen different button pushings and data inputtings, all of which had to be got right, and only by him watching me do it and heckling me could I be sure that I was getting it all right. Any one of these half dozen things could have gone wrong if I'd done all this for real without Patrick's preparatory tutorial, and if something had gone wrong it would have taken an age to sort it all out.

So far so very helpful, but then in the pub afterwards with Patrick I learned something even more helpful, this time concerning how I could make better use of my Canon A70 digital camera. Crucial to this story is that Patrick also has a Canon A70 digital camera. And what is more he had his with him. And what is even more, I had mine with me. In the pub.

I can't remember why I got talking about my camera. I think I was boasting about some indoor photos I took and stuck up at my Culture Blog, using a tripod to keep the camera still. Ah, said Patrick, there's another thing you can do to deal with that. If you switch the nob on the top from AUTO to P, and then press FUNC, and then press the MF button (which is the lowest one of the four you know, other buttons that are in a diamond, if you get my drift which you probably don't which is my whole point here) until you get to the bit that says "ISO Speed" and then take it up from 50 to 400, and then take your indoor photos, they'll come out far better.

I didn't have a Flash Card in my camera. If I had, I would have been able to satisfy myself of this truth immediately. As it was, I was able to make the necessary adjustments in the pub but was only able to take some photos after Patrick had gone. Which I did, and very good they looked too.

When people talk about how you ought to "get out more", they're not just talking about you getting drunk more often and propositioning more barmaids and vomitting over more strangers. They are talking about you learning more.

This sort of dialogue can happen in long distance chit chat, over the phone for example. But it is far more likely to happen in face-to-face contact, because when you are face-to-face you talk about all kinds of stuff, and signal all manner of ignorance and invite all kinds of educational comment.

And the other vital thing is that we both had the identical piece of kit. This meant that Patrick could show me then and there what I had to do. Push this, twiddle that, etc. Because here's another Key Point. I have only the dimmest idea of what all that nob-twiddling actually achieved. Had I had to understand the abstract principle being deployed here, which I would have done if I had wanted to get the same principle working on a different digital camera, I doubt if any of this would have worked.

The key point is that I didn't ask Patrick a deliberately targetted question. I was merely rambling, and he then volunteered the information. I didn't know there even was a question.

But of course, now that I have been out (and more to the point, now that Patrick has) I have an actual question to ask Now, distance learning can swing into action, because now I am aware much more precisely of my ignorance. How is it that, whereas before, when I took indoor photos in artificial light, the slightest wobble blurred the picture hopelessly, but now, with my camera's "ISO Speed" set at "400" instead of 50, I was able to take a bunch of amazingly well focussed self portraits simply by holding the camera out and pointing it back at myself, and clicking, with all manner of wobbling going on? I'm guessing that 400 means that the camera opened and shut, so to spea, much more quickly, and hence the wobbling, which was still going on, actually did far less blur damage. Yes? But if that's so, how come the picture still came out properly balanced, instead of nearly pitch black?

And here's another question which I can now ask, this time because I can be reasonably hopeful of understanding the answer. Suppose that, instead of having a thumbnail picture in this text that showed the whole photo of Patrick (only in miniature), I had wanted to have a thumbnail which merely showed Patrick's face, and then when you clicked on it you'd only then get the whole photo. How can that be contrived? I've seen it done. But how is it done?

Answers in the comments section to either of those two questions would be most welcome.

Brian's education continues.

Posted by Brian Micklethwait at 01:11 AM
Category: Brian's educationLearning by doing

You're already almost there Brian. You have your small image, "patrick-thumb.jpg", linking to a larger version of the same picture, "patrick.jpg".

I assume you're generating your thumbnail version automatically. If you want to crop it differently from the larger version - often a good idea - then you need to crop it manually using the "crop tool" in Photoshop (about 4 down inthe left column of the Tools palette, in Photoshop 7), set the dimensions you want, crop it to the smaller size and then do a "Save As" xxx-thumb.jpg.

Hope that makes sense/helps

Comment by: Alan Little on February 18, 2004 10:24 AM

I'd say the ISO speed simulates a differenet speed film. I'm not an expert but I think it goes like this.
Higher speed films react to the light much quicker than lower ones so, as you guessed, the shutter doesn't have to be open for so long.
400ISO films are recommended for low light conditions while 100 are for bright conditions. That's the rule of thumb for a basic small lens compact camera. When you have an SLR with a bigger lens more light gets in anyway and so a 400 is probably redundant and an all purpose 200 a better bet.

There is a trade off as always which is high speed films don't enlarge very well at all as the image is rather grainy.

Comment by: Mark Holland on February 18, 2004 11:05 AM


You're broadly right about what higher "ISOs" do in digital cameras, although how they do it is different from film.

High speed film has bigger grains of light-sensitive material, so that in any given length of time more photons will hit any given grain, thus making the film more light sensitive. Digital cameras do it differently: obviously the size of the pixel doesn't change - instead at higher "speeds" the camera will try to get a sensible reading from fewer photons hitting the pixel in the same period of time. Smaller amount of photons = more statistical variation between adjacent pixels = more "noise", i.e. different readings from pixels that "should" be reading about the same. This results in "noisier" digital images - irregular speckly colour in areas that should be evenly coloured.

More noise using digital cameras at high "ISO" speeds is sort of similar to more grain using faster films. A lot of people prefer digital to film for high speed shooting, especially in colour - noise is less obvious than huge grain and easier to fix in Photoshop.

This also explains why digital SLRs are capable of producing much better images than small digicams with similar pixel counts - the sensors in SLRs are physically far bigger, so at any given speed they always have more light hitting each pixel and so can get more accurate, less noisy images.

Comment by: Alan Little on February 18, 2004 12:46 PM

Well, I'm glad someone benefited from my advice. On the way home I tried out for myself. The results were not good.

Comment by: Patrick Crozier on February 19, 2004 09:56 PM
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