Tuesday, April 11, 2006

A tutorial...

Just a small experiment. One of my first uses of CS2 and also to illustrate a previous question on backgrounds - to take or not...

Please don't feel you have to rate this, it is not 100% finished yet, I am look for a tutorial type reply. Should I have shot this, what could I have done different with the shot or the post process? Is it worth work or am I trying to create something that was not there to begin with...

Original shot from camera:

The worked on shot:

What is the photo of

A camel jockey and his camels...

When was the photo taken

31st March 2006, 1pm

Where was the photo taken

Nad Al Sheba Camel Pens, Dubai.

Why was the photo taken

Out experimenting with locations and shots, trying to get in close, using the point and shot, but having little success with compostions and backgrounds...

Why was this composition chosen

As I mentioned in a previous question, the question was whether to take the shot even though I know the backgroun let it down.

How was the photo taken

The Sony point and shoot, 1/500, white balance sunny, ISO set to 200.

How was the photo processed

Level balanced using highlight and shadow points identified with threshold layer. Slight boost to the curve, cloned out the pylons. Added blue gradient for the sky, dodged out the jockey. Cropped. Should probably sharper using smart sharpen...


Critical Light said...


I think you have done a good job improving the photo from what it originally was. The removal of the pylons was a must and was done well, as far as I can tell. The sky was cropped which is good. As for sharpening, I have never used smart sharpen but rather the unsharp tool (which actually sharpens rather than unsharpens the image) which I think is better but cannot remember exactly why. Ivan may be able to advise on this.

However, I don't like the composition. To me, it is too busy. Removing the pylons and cropping the sky, as I said, was a good thing. Makes the image look cleaner. But there are too many camel heads and bodies in the photo, so that when you first look at it, the eye doesn't know what to look at. There are too many things competing with the main image; the man on the camel. I do like the way that man and the camel are both looking at the camera. I am not sure whether the camel's head, however, is in sharp focus. With an image like this, you need sharp focusing.

When I compose a photo (and I have since read this in articles), I always try to simplify the image. Remove the clutter. So that the point or rather the image that you are trying to portray is immediately clear to the viewer's eye. The man on the camel is clean and simple, but the other bodies and heads in the picture confuse the eye.

Well, thats my point. I think you have done a great job though on improving this image. If I shot this, I would have tried to isolate the camel and man (I may try this) and I would have shot with a wide aperture (as close to 5.6 as possible) at an ISO of 100 so that I could blur the background. Taking the ISO to 200 means the camera is less sensitive to light and makes it more difficult to shoot at wide apertures when there is so much light. Less than ISO 100 would also be good.


Anonymous said...


The higher the ISO, the MORE sensitive the sensor is to light, not the other way round. It makes it easier to shoot at narrow apertures as the ISO increases, since it compensates for the decreased amount of light getting in by increasing sensitivity to that light. Higher ISO = higher digital noise, especially in point and click. Stick to 100 if you can, 200 max, unless you have a DSLR, like the 350D, which is beautifully noise-free up to about ISO 800. Above that, still acceptable, and you can use something like Noise Ninja, or via the RAW control, to ameliorate noise levels. Many cameras don't go below 100 anyway.

I dug deeper into this, and (via Wikipedia) found this:
What is the meaning of ISO for digital cameras?
For digital cameras, ISO is shorthand for the ISO 12232:1998 specification maintained by the International Organization for Standardization.

This standard specifies signal to noise ratio and brightness requirements (or saturation for cameras that are limited by well capacity) for a camera to earn a certain ISO rating. These ratings are intended to be similar to those of ISO 5800:1987, which specifies ratings for film. Thus, at a given f/stop, shutter speed, and ISO, both film and digital exposures should produce roughly the same brightness as output. Note that in practice this isn't always the case due to many factors including interpretation of the standard, different tone curves, rounding, and marketing considerations.

As with traditional film ISO ratings, increasing the ISO corresponds to an increase in sensitivity. For example, in moving from ISO 100 to ISO 200, while keeping the f/stop constant, you will achieve the same exposure by using a shutter speed twice as fast.

In practice a single camera can achieve multiple different ISO ratings by applying some form of amplification to the signal coming off the sensor. This can be done by applying analog amplification to the signal before it hits the A/D converter, or by bit shifting the results after they have gone through the A/D converter. Cameras may apply a combination of these approaches, depending upon the desired ISO. Which is best will depend upon whether amplifier noise or A/D converter noise is larger.



Unsharp mask is by far the best way to sharpen. It's a term taken from traditional wet photography and a good link is from our old pal The Luminous Landscape (but I keep on telling you guys how good this site is, so no excuses really!). Usually recommend an amount of 100-120% and a radius of 0.7-1.0. For 350D images (apparently) it's 300% and 0.3 radius. I (perhaps mistakenly) multiply the percentage by the radius, and if the number is roughly the same, the effect is too, but I think it's less subtle at the top end.


Phew! Interesting topic. Good work on CS2.

Critical Light said...

Good info. Need to read that again...

I apologise for the error with ISO and light sensitivity...I know that 100 is more sensitive not less. My fault. I usually stick to 100 but it's good to know that the 350D can handle noise free shooting at ISO 800. I usually forget to play with the ISO. Its a shame that it doesn't go to 50.


Anonymous said...


I think you may still be a bit confused - you originally said:

"Taking the ISO to 200 means the camera is less sensitive to light and makes it more difficult to shoot at wide apertures when there is so much light. Less than ISO 100 would also be good."

Then, in the last post, you said:

"I apologise for the error with ISO and light sensitivity...I know that 100 is more sensitive not less. My fault."

If I read this right, you maybe still think that 100 is more sensitive than 200? The higher the ISO, the higher the sensitivity. So, 100 is more sensitive than 50 (which you may have been referring to) and less sensitive than 200.

ISO 100 is the most common low-sensitivity setting, so it's no big issue that it goes to 50. If it did, you'd need even longer exposure times and the difference in digital noise would be so miniscule that you'd never notice it.

I'd play around with ISO, as it's one of the huge advantages of having a digital SLR - the ability to effectively "swap film" mid shoot. Also, one of the main reasons, after lens interchangability, for having a DSLR is the excellent signal to noise ratio at higher ISOs compared with point and shoot. Larger sensors mean more light per sensor cell, therefore better picture rendition at the higher sensor amplitudes. Small point and click, photocells close together and get less photon per cell, therefore they have to artificially boost the signal = noise. An 8MP compact will NEVER be as good as an APS sensor DSLR (like the 350D), and the 350D will never (at higher ISOs like 1600+) be as good as full-frame DSLRs like the Canon 5D or IDs Mark II. I would encourage you to use ISO 100-200 more often, 400 when it's a little dark, and 800-1600 when you really need to. However, nothing beats ISO 100 at 30 sec + exposure for clean images, but the higher ISOs mean you can capture faster moving images with faster shutter speeds hand-held in not-optimal light. Play around and see. Also, if you use RAW, the noise reduction algorithms are great, so no reason not to use 800-1600, and certainly up to 400 will be virtually noise-free. The 350D leads it's class in this respect.

Critical Light said...

right, I think I have it now...I think...does make sense...