Choosing a lens for a Reflex camera


Which is more important a lens or the camera

For a final image quality,  for a digital SLR (single lens reflex camera) a lens has more impact than the body. For this reason it is more important to spend more time choosing a good lens, or invest more cash into lens. In order to have the best choice we need to understand what we need. There are basically two types of lens existing: a prime (single focal length lens) or a zoom lens (a certain range of focal length, like on most compact cameras, 18-55mm,70-300mm, 100-400mm). If we want convenience and multi purpose usage we uses zoom lenses, for specific usage, uses primes. Primes are usually sharper, has more contrast, more light  gathering capability than the same price category zooms.

[do_widget Text]

A lens usually identified by numbers, for example a zoom lens 18-55/3,5-5,6

The first two numbers are the focal length range in mm, the second numbers are the brightness of the lens. The smaller numbers refers to better brightness. For example f1,8 lens is brighter than an f4 lens. The first number refers to the first focal length(18mm), the second refers to second focal length(55mm).

Or a prime lens 100/2,8 First number the focal length, the second number is the brightness or light gathering capability.

The brighter lenses are usually sharper and more expensive (usually brightness in direct relation with the glass size).

If the number is smaller than 2,8 these are good light gathering capability lenses.

About the focal length:

There are a lot of different format cameras according to their sensor sizes started from several millimetres to several centimetres. The same lens has different field of view in different sensor cameras. For digital  reflex cameras the 2 most used size is full format FF (36*24mm) and Aps-c (22,5-15mm or little bit smaller or bigger).

Basically we identify 3 different type by focal length:

1. Normal lens, similar field of view as human vision. In full frame 50mm, app. 30mm on Aps-C

2. Wide angle, more wide, or smaller focal length than 50mm on FF, smaller focal length than 30mm on Aps-C

3. Telephoto, with narrower field of view. Longer than 50mm on FF, longer than 30mm on Aps-C. If the focal length is more than 300mm we can call a lens super telephoto.

The same lens has different field of view in full format, or Aps-C.

Perhaps a good start to choose a lens is the focal length.

Inside in a room without external lighting, without strong internal lighting and if we don’t want to use flash, we need f2-f2.8 or better brightness lenses according to my experience in order to make sharp pictures (at ISO 1600 or ISO 3200.) Image stabilisation helps for non moving subject, but not for moving subjects.

To evaluate a lens, a following caracteristics are important:

  • Sharpness
  • Contrast
  • Colours
  • Light gathering capability
  • autofocus operation
  • Not anybody likes to change lenses all the time. (Me included). So the idealistic choice would be the one lens solution. For example Tamron 18-270 Vc. This choice would be the most convenient usage: never changes lenses, one lens all the time. This lens perhaps good at the wide angle, small telephoto area, but certainly not good enough at the telephoto area.(slow focus, weak light gathering capability). I prefer to have a lens that is good everywhere where I am using, and have enough light gathering capability. The best choice can be a 24-105f4 L, or the 15-85 IS for Canon, 16-85 ed Vr Dx for Nikon, in this cases we have better quality but not so wide range.

    The second step is the 2 lens solution: one wide angle, one telephoto. We lost convenience, but gain much better picture quality, in this case much better focus operation, light gathering capability. For example (Tamron 17-50, canon 70-200f4). This two lens cost much more than the one lens solution of course.) The two lens solution can cover a basic photographers need, if you don’t want to spend your time buying lenses, and two lenses is enough, you choose this two lenses after you can go shooting. If you likes photography a lot, there hundreds of options to buy different lenses. (macro, fish-eye, long telephoto prime, super wide prime, tilt – shift, etc.)

    If you want good quality lenses you need to pay, or spend all your time searching adverts used old manual focus lenses, auctions, etc. You can’t have anything for nothing. On the other way, if you pay a lot, does not necessarily mean you get what you wish for. If you are not a millionare, you need to make compromise. I don’t recommend to spend all your income on lenses. You can decide what is your budget, and you can check what you can get from that money. If you don’t have enough money to buy a dsrl and good lenses, better to have a superzoom compact, and enjoy shooting. (Used panasonic fz50 for example). Good quality used lenses much better than bad quality new lenses. I don’t recommend to buy used lenses to everybody though, because you need to be sure what you want, you can get faulty equipment, get cheated, etc.

    Good price/good quality lenses:

    Canon 18-55 is, Canon 70 – 200 f4l, canon 50/1,8,  tamron 17-50f2,8, canon 200/2,8 L, Sigma 150/2,8, Nikon 35/1,8, Samyang 35/1,4, Samyang 14/2,8

    if a lens is not in the above list does not mean it  is not good, more that I don’t know about.

    does not necessarily means that all copy of this lenses are equal in terms of optical performance, can have defective ones, damaged etc.

    For an APS-C dsrl (sensor size 22,5-15 mm)

    In order to built a full kit my priority:

    1. Have a general purpose, or wide angle lens (17-55, 18-55, 17-40, 10-22,17-70 mm).

    2. Have a telephoto 70-400 mm focal length (prime, zoom)

    3. Have a low light lens (50 F1,4-1,8 85/1,8 100/2)

    4. Have a macro lens if necessary (100-150mm f2,8 for example)



     Posted by at 12:17 pm