The subject gets too bright and the background goes too dark. Please note that I am not technically minded. Is there a way out?
D. F. Kalyaniwala, Mumbai
We’ll first take the background darkening issue. Some users, when using flash, set their cameras to manual exposure mode with the shutter set to the x-sync speed (which is 1/200sec for the 1000D). They then use the formula – ‘Guide Number divided by the distance equals Aperture’. I presume you are doing the same. With flash photography, the flash illuminates the subject in the foreground. The background illumination depends on the ambient (available) light. Now, if your shutter speed is high (say, 1/200sec) it does not give enough time to record the available light, which is already low to start with. Hence the background gets underexposed (dark). Try a shutter speed of, say, 1/30 sec and see the difference. If you use a tripod, and the subject stays still, you can use even slower shutter speeds for more brightness in the background. This technique is also known as ‘slow-sync’.
Now let us consider your problem you face with overexposed foreground subjects. This is likely to happen if the background is dark (I am now assuming that you are exposing in one of the priority modes). Check if there is a provision for exposure compensation on your flashgun. If so, set it to -1 stop and try. Some fine-tuning may be required.
Note that a flashgun is a point source of light, and therefore by nature is harsh. Try firing the gun through a flash umbrella and see how the light gets ‘soft’. If your flashgun is powerful enough, and you have a low white or off-white ceiling, you could even try bouncing the light off the ceiling. These two methods will also ensure better modeling on the subject’s face, without the ‘harshness’ you describe.
A ‘bit’ of confusion
Can you please clear my confusion about 8-bit, 12-bit and 16-bit images? They say that 16-bit is better but in what way is it better?
R. R. Desai, Mumbai
Let’s first try to understand what the term ‘bit’ means. In computer language 1-bit means 2 raised to the power of 1 (21 or 2 tones; black and white). 2-bit would mean 2 raised to the power of 2 (22 or 4 tones; black, white, dark gray, light gray). 3-bit would be 23 (or 8 tones). Continuing this way, you come to 8-bit (meaning 28 or 256 tones). 8-bit images have continuous tones (that is, the tones do not break up or cause banding/posterization). JPEG images are 8-bit per channel. This is the same thing as 24-bit images (since our images have 3 channels, Red, Green, and Blue). Note that you either say 8-bit per channel or 24-bit image. Since there are 3 channels of colour in our images, the total possible colours (theoretically) that a JPEG file could provide is 256 x 256 x 256 or 16.7 million possible colours.
Some cameras allow you to shoot in RAW. RAW images can be either 12-bit per channel or 14-bit per channel. 12-bit per channel (same thing as 36-bit image since we have 3 channels) means 212 or 4096 tones per channel. Again doing some elementary math tells us that the total possible colours in a 36-bit image is 4096 x 4096 x 4096 or 68.7 billion possible colours. Similarly, 14-bit per channel or 42-bit image could possibly have 16,384 x 16,384 x 16, 384 colours (over 4.3 trillion colours)
As you must have deduced by now, more the number of colours, smoother will be the image tonality.
But ‘hold your horses’, you say. You mentioned earlier that, “JPEG images give us continuous tonality.” Then why should we bother with having so many more colours? The short answer is that during post-processing, it is possible to lose out on millions of colours. If you were to lose millions of colours from a JPEG image, you are likely to end up with banding/posterization. With RAW capture, you start off with many more colours than you need, and hence the loss of colours during post-processing is unlikely to cause postarization.
Our 35mm format cameras (currently) do not allow us to shoot in 16-bit (We have only 12-bit RAW or 14-bit RAW). Even then, we need to edit in 16-bit mode when we open a RAW file in our RAW Converter. We certainly do not get the additional advantage of the 2-bit or 4-bit, but we do not get the disadvantage of 8-bit! After the editing is over, we need to convert the file back to 8-bit since printing is done in 8-bit mode. Hope this clears your confusion.
Since White Balance can easily be adjusted in post processing of RAW files, does it make sense to go through the hassle of setting the correct WB during the picture taking stage?
Raman V. via email
Though some Photoshop gurus feel that it is not necessary to ensure perfect WB if you are shooting in RAW, I say it does make sense to ensure proper White Balance even when shooting in RAW. When you start editing with neutral colours, it is far easier to ‘warm up’ or ‘cool down’ the image in your RAW Converter for esthetic reasons and/or personal preferences. This is assuming that your monitor is colour-calibrated.
I would like to add here that any colour modification you do to your image is futile, unless your computer monitor is colour calibrated. As an example, let’s say that your monitor exhibits a light blue cast which you are unable to notice (which is quite possible). You think that the colours are perfect. Now, you wish to add a little ‘cooling’ effect and hence add some blue. The earlier blue cast (which you could not notice), and the purposely added blue will combine.
Needless to say, when you send the file for printing, you will be very disappointed. If your WB was perfect when you shot the picture, you would have started the post-processing with ‘neutral’ colours. Even if your colour calibration was off, neutral colours plus non-calibrated (or imperfectly calibrated) monitor equals reduced degree of error.
Best retouching software
I like to do portraits. Which is the best portrait retouching software?
Abdul Ali Khan, Lucknow.
I’m sorry I cannot answer this question with any authority as I have not tried the various available software for portrait retouching. I’ll also tell you why I haven’t tried them: they tend to turn every lady in to ‘Helen of Troy’. In other words, most of these software make the subjects appear as if they were plastic moulds (Barbie dolls?) – with absolutely smooth and flawless skin. Whilst I do like women with flawless skin, these software tend to overdo things. Having said that, it may be possible to control the degree of ‘plasticity’, but as I mentioned before, I haven’t tried them. When required, I like to create the effect of a good soft effect filter (diffuser) using Photoshop.
Mobile Phone Cameras
When do you think, if at all, mobile phone cameras will be as good as conventional?
– A question put up by a stranger at a party.Predicting the future is not my business (though I do try sometimes!).
Unless mobile phones get abnormally large in size (and consequently use larger image sensors), I doubt if they can match (or nearly match) the image quality from a conventional compact camera. It is possible that technology may prove me wrong though.
The image quality from mobile phones are improving every day. If you are not over ambitious, you may be pleasantly surprised.