Buying a DSLR ?

08Nov11

It’s not uncommon to find people with a DSLR these days. Few years back it was not affordable to common people and big brands like Canon and Nikon have introduced a wide range of entry-level DSLRs which is almost similar to high-end point and shoot cameras. It is good to think a few things before you plan to invest on a DSLR because after spending a huge amount its better not to feel, “oh this wasnt the one I required…”

I would suggest a point and shoot (P&S) camera for those who are impatient, just because of one reason. DSLR cameras would allow you to set the shutter speed, aperture more effectively than in other P&S cameras. To set all these parameters well before clicking one must require a little amount of patience. Professionals who uses their DSLR like a toy will have lots of experience and they can easily understand what are the values that has to be set for the correct lighting situations so that he gets a photograph which is not over or under exposed. Then one can ask, even the DSLRs have an automode which ease the task of setting the values and why cant that be used so that the photographs would be exposed well. If thats the case, go for P&S which will fit in your pocket and take anytime anywhere you want and why spending more on a DSLR ?

Another conern about these DSLRs are its maintenance. It has to be stored well so that the camera body and lenses wont get affected with fungus. And once it shown up in the sensor or the lens it is very unlikely that it wont come again. It is really tough to clean is so well so that there wont remain any spore of fungii which will again grow there inside. In case of P&S you don’t have to worry about taking care of each lenses. I think thats a very good reason to consider P&S for a normal and regualar use.

What are the basic things that has to be cheked before selecting a DSLR ?

Focus motor

If your camera has a auto-focusing motor built-in the body it is well and good. That would be the first and foremost thing that you have to make sure before choosing a model. Why is it so important ? Because, once you start shooting with a normal kit lens say, 18-55mm there is every possibility that one would think that, “No, this doesn’t have enough zoom” and after seeing a few colourful macroshots in flickr one would feel like taking pictures of tiny creatures, pollen grains and other mini wonders around us. So, they will end up in buying new special purpose lenses. Now  the importance of auto focusing motors comes into picture. To allow auto focusing the lenses has to adjust themselves and it is done by this motor. If this motor is present in the camera body, then you can go for cheap lenses that doesn’t have a motor inside. If your camera doesn’t have a motor, then to do auto focusing every lens you buy requires a motor and such lenses would cost much much more.

Cleaning Mechanism

Dust particles on the sensors are another concern of many DSLR users. Some new models come with a self sensor cleaning mechanisms. What it does is, the sensor will be vibrated in a high frequency which will clean the sensor from the dust particles residing on it. Its a good feature to have if it all it can clean the sensor well. I have seen sensors that have become so dusty though it had the cleaning mechanisms. So its better to take special care about this even if you have a camera which has cleaning mechanisms. But it’s always good to have such a feature than not having it!

There are many more features like high speed continuous mode, HD Recording, Movie recording etc. New features are getting added in every new models. Those are all up to the user which one to go for. What I believe is if you know well how to use a manual more in a dslr then no matter which ever model you buy which ever features you have, you will be able to click decent shots.

About sensor size

There are differenent classes of DSLRs. The main two are, DSLRs which have fullframe sensors and DSLRs that have cropped sensors. Let us see how does the sensor size would affect the photographs…

Crop Factor

Full frame cameras have a sensor size equivalent to 35mm film frame. There are certain advantages and disadvantages with the bigger sensor sizes. Full frame cameras can capture the whole image formed on it, that means the angle of view is better in full frame cameras since it covers the entire view. A small portion of the formed image will be lost if the sensor is small as it falls outside the sensor area. So the Field of View (FOV) will be lesser in case of sensors which are not full frames.

SesorSizeComparison

Now it is time to introduce the term crop factor. Crop factor is the sensors diagonal size compared with a full frame sensor.  For example, Nikon D40 has a sensor size of 23.7mm x 15.5mm (APS-C sensor). Size of a full frame sensor is 36mm x 24 mm.Crop Factor = Diagonal(36×24) / Diagonal(23.7×14.5) which is equal to 43/28 approximately 1.5. So crop factor of Nikon D40 is 1.5. This is also called as Focal Length Multiplier. When a 50mm lens is used on a APS-C sensor which has a crop factor of 1.5, then it is equal to using a (50×1.5)mm lens on a full frame camera.

Depth of Field

Depth of field is the distance between the nearest and the farthest object in an image. The following two figures will explain it. The image on the left is shot af f/36 and the other at right side is shot at f/5.6 and you can make out the DOF of the first image is deeper than that of the second one.

DOFComparison
Depth of Field (DOF) of the over all image is another characteristic that varies based on the sensor size. At a particular F-Stop the focus of the subject reduces as we move out from the centre of the image, so we say DOF will be more on the centre of the image. So when using a non full frame sensor, the area which is not in focused would get cropped and the DOF of that photograph will be better. So lesser the sensor size deeper the DOF will be. But it wont be so obvious in normal cases.

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One Response to “Buying a DSLR ?”

  1. Good post , but too technical for me 😦


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