Understanding lenses, can anyone teach me?

[Photo Marksman]

I am so confused about lenses, I read something about them but english is not my first language so I don't really understand anything. For example how do I read:

TELEPHOTO 55mm f1.4 MC DA Lens

 

[KmH]

I am so confused about lenses, I read something about them but english is not my first language so I don't really understand anything. For example how do I read:

TELEPHOTO 55mm f1.4 MC DA Lens

Telephoto means it gives a field-of-view smaller than what your eye sees (the lens magnifies or seems to bring things closer).

55 mm is the lens focal length. Since it has only one number it is a prime lens not having a zoom feature. Zoom lenses have 2 numbers the shortest and longest focal lengths the lens can be zoomed to, like 18 mm - 55 mm.

f/1.4 describes the maximum lens aperture diameter, in this case: 55 mm/1.4 = 39.3 mm. If a lens has a 100 mm focal length at f/1.4 the maximum lens aperture diameter would be 100 mm/ 1.4 = 71.4 mm.

Without the brand name of the lens the meaning of MC and DA could vary.

 

[enzodm]

I'm sure there is a national forum on photography in every european country, if english is a problem (I'm also subscribed to an italian forum).
By the way, if you have to learn all about photography, perhaps a good book is the right place to start with (and, yes, this is studying). Keith' explanation is perfect, but if you do not know what influence has aperture on pictures, it is not meaningful for you to know lens aperture.

 

[Christie Photo]

Telephoto means it gives a field-of-view smaller than what your eye sees (the lens magnifies or seems to bring things closer)

AND... the focal lengths considered "telephoto" relate to the format of the camera. For some cameras (those referred to as full-frame), 55mm is considered a "normal" lens... one that approximates what your eye sees.

55 mm is the lens focal length. since it has only one number it is a prime lens not having a zoom feature.

I suppose "prime" is a perfectly good word. It is in wide use. Just remember it refers to "fixed focal length" (FFL) lenses.

-Pete

 

[ghache]

He doesnt understand the web explanations because its in english. he wont understand your post either.

 

[Photo Marksman]

I am so confused about lenses, I read something about them but english is not my first language so I don't really understand anything. For example how do I read:

TELEPHOTO 55mm f1.4 MC DA Lens

Telephoto means it gives a field-of-view smaller than what your eye sees (the lens magnifies or seems to bring things closer).

55 mm is the lens focal length. since it has only one number it is a prime lens not having a zoom feature. Zoom lenses have 2 numbers thye shortest and longest focal lengths the lens can be zoomed to, like 18 mm - 55 mm.

f/1.4 describes the maximum lens aperture diameter, in this case: 55 mm/1.4 = 39.3 mm. If a lens has a 100 mm focal length at f/1.4 the maximum lens aperture diameter would be 100 mm/ 1.4 = 71.4 mm.

Without the brand name of the lens the meaning of MC and DA could vary.

Thanks, I think I understand now, the Lens is a Pentax by the way.

 

[KmH]

I am so confused about lenses, I read something about them but english is not my first language so I don't really understand anything. For example how do I read:

TELEPHOTO 55mm f1.4 MC DA Lens

Telephoto means it gives a field-of-view smaller than what your eye sees (the lens magnifies or seems to bring things closer).

55 mm is the lens focal length. since it has only one number it is a prime lens not having a zoom feature. Zoom lenses have 2 numbers thye shortest and longest focal lengths the lens can be zoomed to, like 18 mm - 55 mm.

f/1.4 describes the maximum lens aperture diameter, in this case: 55 mm/1.4 = 39.3 mm. If a lens has a 100 mm focal length at f/1.4 the maximum lens aperture diameter would be 100 mm/ 1.4 = 71.4 mm.

Without the brand name of the lens the meaning of MC and DA could vary.

Thanks, I think I understand now, the Lens is a Pentax by the way.

You will see lenses that have even more numbers, like

24-85 mm f/2.8-4, known as a variable aperture, zoom lens.
That means the lens focal length can be varied (zoomed) between 24 mm and 85 mm.
The lens can only be set to the maximum aperture of f/2.8 at the 24 mm to about 26 mm focal lengths. In other words the aperture will not stay at f/2.8 as the lens is zoomed towards 85mm. The aperture will automatically change (vary) as the lens is zoomed to the longer focal lengths. From about the 65mm focal length to 85 mm the maximum lens aperture will be f/4.

Lens aperture is one of the 4 factors that controls depth-of-field (DOF): Understanding Depth of Field in Photography

I highly recommend all the tutorials there at CambridgeInColor.com and I have some basic information on my blog: How Do I Use My Digital SLR?

 

[Photo Marksman]

Thank you so much! Another question, how do I know which size polarising filter I need for a certain lens?

 

[dxqcanada]

You may possibly see a ⌀ symbol on the lens ... it will be in mm.

or the lens spec sheet http://www.pentaxcanada.ca/digital/digital_slr/da_lenses/DAStar55_F1.4SDM.php