How do you read a lens?

Question

1.

Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom Lens

can someone please break this down so I can understand how to read this please?

2.

Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom

Canon EF 70-300mm f/4.5-5.6 DO IS USM Telephoto Zoom Lens

why would anyone want a zoom lens that stops at 85MM, isnt the larger the number better the zoom? Wouldnt the 300mm be much better because it zooms in better?

Answer 1

Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom Lens

Canon - you already know what that means

EF-S - refers the lense mount. Compatible with only certain cameras (crop cameras)

17-85MM - focal range

4-5.6 - Refers to the aperture range. At the short end(17mm), the widest is 4 and at the long end(85mm) the widest is 5.6



IS - Image Stabilization it allows 2-3 stops below the minimum shutter speed to avoid camera blur.

let's say you're shooting at the 85mm. on the crop camera, you would need about 1/136, on my camera it goes from 1/125 then 1/160, so i would go to 1/160.

Let's say the meter says that the proper exposure is 100. Thats 2 stops slower than what you can handhold. This is where the IS allows you to take the shot.

USM - Ultrasonic Motor

faster focusing and quieter

Standard Zoom Lens -  Is just that standard zoom lense

Canon EF-S 17-85MM f4-5.6 IS USM Standard Zoom

Canon EF 70-300mm f/4.5-5.6 DO IS USM Telephoto Zoom Lens

why would anyone want a zoom lens that stops at 85MM, isnt the larger the number better the zoom? Wouldnt the 300mm be much better because it zooms in better?

No - I have a Tamron 28-300 and I just got the Canon EF-s 55-250mm IS. Why?

The Tamron 28-300 is a superzoom. The range is great but the image quality is not on par. The longer range means more elements that means less overall light that hits the sensor with that particular lens attached. That reduces the image quality(IQ). That's why the Tamron lenses cost less.

This is also why prime lenses have better IQ and are expensive, compared to the telephoto.

Answer 2

Canon is the manufacturer of the lens, meaning that the lens will mount onto a Canon body.

The focal length (e.g., "70-300mm) is the field of view that the lens can see. A "Normal" focal length is about 35mm on a consumer Canon DSLR and 50mm on a 35mm SLR. This gives roughly the perspective that we, as people, see. A wider lens can see more of a scene (think really big landscapes), but the perspective is exaggerated and as something gets close to the camera is starts to appear much larger. An example of this is the classic image of a dog poking it's nose towards camera; the nose will look really big while the rest of the dog is small because it's further back. A telephoto lens makes a distant scene look bigger (smaller field of view) and also flattens the picture. Think of a telephoto lens as being like a pair of binoculars and a wide angle lens as being those binoculars turned around backward.

EF stands for "ElectroFocus." This means that it is autofocus and will mount on an EOS camera (Any DSLR, recent 35mm SLR's too). An acronym of EF-S means that the lens will only work on cropped-sensor (aka, APS-C) DSLR's such as the Rebel series (or 300D/350D/400D/450D/1000D) and 10D/20D/30D/40D series. It will mount on any EOS camera, but light will not hit the corners of the image sensor or film on a non-cropped camera, and this will result in a big black circle near the edges of the image.

IS stands for image stabilization. This means that there are mechanisms in the lens that helps reduce the shake caused by hand holding it, which in turn makes it easier to shoot sharp images in low light situations.

USM is an UltraSonic Motor. A USM mechanism is virtually silent, and generally focuses much faster than non-USM glass.

DO means "Diffractive Optics" in Canon jargon, and DO lenses can be identified as having a green ring around the lens body towards the front of the lens. Diffractive Optics is a technology that allows very sharp lenses with virtually no chromatic aberration. These lenses are normally a bit smaller than one would expect for their focal length/speed as DO is used to reduce the need for huge pieces of glass, but these lenses are also very expensive. I've never heard of a bad DO lens.

Zoom, of course, means that the lens can change it's focal length -- zoom in and out. Zooms have generally lower image quality than a comparable fixed or prime lens, that does not zoom. A bigger zoom range does not imply better. As lenses are made to zoom more, they lose image quality because you're trying to make the same glass work for a wide range of focal lengths. Basically, you're making the glass perform at an okay level for any given focal length, but never excel at any given one either. A fixed/prime lens will usually give the best optical quality. After that, a small zoom range (16-30mm) will give the next best quality, then a medium zoom range (18-55mm), and a large zoom range (18-200mm or 70-300mm) will give the least optical quality. This is just a general guideline of course, optical quality varies significantly from lens to lens. The 17-85mm IS lens will be a better option if you had to choose just one lens right now, as it covers the "Normal" range, which is where the majority of your shots will come from. The 70-300 DO is an amazing lens, and would be a great second lens.

The f/# is the maximum aperture of the lens. A smaller number is generally better, as the lens can perform in lower-light situations and can also "Sweet spot" (get to it's best working conditions) at a lower aperture as well. A bigger aperture (lower number) means that there is a bigger hole for light to pass through in the lens, which means more light reaches the sensor in a given time, and thus the sensor can record the image faster than with a lens at a lower f/#.

Answer 3

300mm has greater zoom capability, but is significant;y larger than the 85mm.  Most folks don't want to lug around a lens that size for every day use.  Plus, on the other end, it starts at 70mm - which is quite a bit larger than 17mm.

In other words, the 17-85 is better for every day use.  The 70-300 is good for when you need the extreme zoom.