The blog of Jafar Aliyev


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Photography tips

This page holds some power tips for beginners and even advanced amateurs.

On-camera flash

Saying on-camera flash means the flash that you plug to the camera hot shoe. But the popup flash of camera means nothing and I recommend you to close it and forget.

Don't use direct on-camera flash to take a photo or U'll partially overexposure the person whom you direct the flash. Always diffuse or bounce the light. Diffusing means to cover the flash with diffusor material. Bouncing means directing the flash to the ceiling or wall, so let the light to travel from surface to the object.

But note, that U can't bounce the light from colored surface. The good way is to use bouncing only on white ceiling or walls, in other case U'll get the white balance shift. In other words, the face of subject will hold the color of bouncing surface. You can't bounce the light in outdoor photography.

The common disadvantage of both methods is losing the power of flash light. If you bouce the light from the high ceiling you'll need more power of flash. Diffusor eats 1-3 stops, hence you must compensate it this with f-stop of lens or with the power of flash.


Why some lenses are expensive and some are very expensive. There are many reasons that make the cost of lens.

First of them is the maximum aperture of the lens. The lens with 1.8, 1.4 and 1.2 aperture will be more expensive than the lense with maximal aperture or 2.7.

The second and more significant parameter is the aperture shift of zoom lenses. Look at your lens. If you see two aperture values 2.7-3.5 this means that in shortest focus of this lens the maximum aperture is 2.7 and in longest focus the aperure will be 3.5. In photographer point of view it means that if you adjust your aperture, shutter and ISO speeds then change your zoom you'll lose your apetyre. Therefore if you can't afford zoom lens with fixed apeture, because these lenses are truly expensive, I recommend you to buy the lens with fixed focus, instead of zoom lens with the same price. The best zoom in this case is the legs of photogprapher.

Fast focus lenses may catch focus faster than regular lenses and are irreplaceable for press photographer.

Coating material of lens glass also makes the price because of anti-flare and anti scratch effect.

Aspheric lenses that have minimal geometric abberation or tilt-shift effect makes sense in photography.

Below I give my opinions on my lenses that I use with my Pentax K20D camera

SIGMA 24mm F1.8 DG Macro AF EX Aspherical

I lately bought this lens. This lens has different bayonet for different cameras. Mine is with Pentax KAF2 bayonet. Sigma 24mm F1.8 is a wide angle lens. I thought I can use it for landscape and macro photography.
My first impession about this lens is not so good. The first thing that I mentioned is focus. I tested it in low ambient light. Testing on human photography doesn't give me positive result because of geometric distortion of face. I know, that wide angle lenses make distortion. Also on high aperture the soft focus takes place. I tried it even on F5.6. The focus didn't get sharper. After some experience I understand, that I can't use it as macro lens. Now I use it as wide angle lens in landscape photograpy and for group of people. I set aperture to F8 and raise ISO to 800 or 1600. With Pentax CMOS it gives preferable result. Now let me write about each parameter separately.

Aspherical: This lens is not quite aspheric. Yes It curves the stright lines. But in reasonable range. I tested it at home with stright edges of furniture. In short lines it looks as aspheric. But on buildinds U can feel the spheric effect.

Focus: Interesting auto/manual focus switch. Like a Winchester gun. You pull the focusing ring to the direction of camera to lock and start moving. When focusing ring on Auto position it runs free. As the lens is not light you can hold it from this ring, if it's on Auto mode, to make macro shot. The ring will not turn. Note that the 20mm and 28mm lenses has the same mechanism. Focusing may be acceptable for Sigma but not for the man who used Pentax genuine lenses (like me). I expected more interesting and accurate focusing for this price. But focus is faster but softer than Pentax DA Limited lenses.

Macro: The minimal focusing distance is 18cm that I think is not an advantage for macro lens.

Aperture: Also the maximum apreture is F1.8 but my Pentax K20D shows F1.7. On larger aperure the blur effect begins on significant distance from edges of lense. The lens has an aperture ring. When move it from Auto mode to the exact value of aperture the camera stops showing you the aperture value and can't set the shutter speed, you must switch the camera to Manual mode. But autofocus continue to work. My Pentax 77mm Limited portrait lens also has an aperture ring and when I take off it from Auto mode it behaves the same.

The next time I'll buy Pentax lens

Useful links

Here is the useful spreadsheet table with comparision of photography equipment

More aspherical lenses from Sigma

Sigma 20mm f/1.8 EX DG RF Aspherical Wide Angle Lens for Canon Digital SLR Cameras
Sigma 28mm f/1.8 EX DG Aspherical Macro Large Aperture Wide Angle Lens for Canon SLR Cameras

Author: Jafar N.Aliyev (Jsoft)