EXTREMELY noob question.

[Markw]

I googled it 1000x and I always come up with the same things. What does mm mean in lenses? I know what it means, but I guess what Im asking is what can a 400mm lens do over a 50mm lens? Is it a matter of zoom (I doubt it)? How does this impact the size of the lens? I know this sounds extremely newb-ish, but This is the ONE thing that I just cant wrap my head around. Every time I research it, I get elaborate terms and unbelieveably complicated diagrams about DOV and focal range that are just too complicated for me. So, simply put, what can a 400mm lens do that a 50mm lens couldnt do, what situations could it handle that a 50mm couldnt? Things like that is what I want answered. Thanks a bundle.

Mark

 

[midlight21]

mm means millimeter but better to let someone else tell you what it means for lenses....i'm a noob too.

 

[AussieDee]

I"m guessing the range of sight. 400mm means it can zoom in at 400mm and a 50mm will only zoom in at 50 millimeters.... ????? 400 is further than 50.

I"m guessing too.

 

[rufus5150]

Heh, someone will probably come along and correct me.... it's the distance, in millimeters, from the lens to the focal point, the sensor of the camera. So if I interpret that correctly, at 50mm, the lens it 50mm away from where the image is recorded. 400mm would be 400mm away (and explains the rather lengthy lenses).

50mm on a 35mm camera is roughly how the world looks without the camera.

At 400mm, things are going to seem a whole lot closer.

Ignore the text, but look at the pictures here: http://en.wikipedia.org/wiki/Photographic_lens#Aperture_and_focal_length

The 4 pictures labeled 28mm, 50mm, 75mm, and 210mm. They're taken from the same standing position, with lenses at different focal lengths.

 

[AussieDee]

So if you wanted to capture wildlife in it's own habitat, so as not to scare the critter, you'd use a 400mm lens - is this correct?

What about macro shots?

 

[rufus5150]

I'm neither a macro shooter nor a wildlife shooter (2 1/2 year olds aside).

As far as I know, the macro lenses are engineered to allow a closer minimum focal distance. How that's achieved would be a good question to have answered here from my perspective.

Almost all of the wildlife photographers I know use either a 300mm or a 70-200mm lens, but none of them are pros.

 

[json2001]

I've been doing a lot of research on lenses lately and after said research the MM is the focal length in millimeters.

Macro lenses are their own special animal as far as I understand:

Using a special-purpose lens called a macro lens (perhaps confusingly, some manufacturers call it a micro), having a long barrel for close focusing. A macro lens might be optimized to provide its best performance at a magnification of 1:1. Some macro lenses, like the Canon MP-E 65 mm f/2.8, can achieve even better magnification— up to 5:1 macro, bringing the structure of small insect eyes, snowflakes, and other minuscule but detailed objects into striking focus. However, it is more common for a photographer to use a "standard" (1:1) macro lens. There are different categories of macro lenses, depending on the focal length:

• 50–60mm range typically used for product photography and small objects
• 90–105mm range the standard focal range used for insects, flowers, small objects
• 150–200mm range gives more working distance — typically used for insects and small animals
• a few zooms provide a macro option, but they generally do not allow a 1:1 magnification

Source

Just read a nice, easy to understand article last night on Lens basics as well. It cleared up quite a few questions I had on lenses.

 

[AussieDee]

I was just guestimating at the 400mm lens thing... roughly that range for wildlife is all. I don't have any lenses. I still use a cheap $99 P&S. one day tho. one day.

 

[AussieDee]

I've been doing a lot of research on lenses lately and after said research the MM is the focal length in millimeters.

Macro lenses are their own special animal as far as I understand:


Just read a nice, easy to understand article last night on Lens basics as well. It cleared up quite a few questions I had on lenses.

Excellent read! Thanks for that link! :thumbup:

 

[prodigy2k7]

mm is the focal length, it is contained inside the lens itself I believe. *NORMALLY* the physically longer lenses, the longer the focal length, and the greater distance you are able to see.

100x zoom is basically how much the zoom changes...

10-100mm = 10x zoom
100-1000mm = 10x zoom

a "x" zoom doesnt mean a certain distance you can see, you might not get very far at all! It just how much the zoom changes, not how far you can see...

 

[KhronoS]

The focal length of the lens is defined as the distance from the middle of the lens to its focal point.

About the difference between different focal lengths:
Well a 10mm lens has a small distance between the last element and the image sensor so it give an extreme wide view
But as the focal length increases the field of view decreases, so thats why you zoom in meaning that at 400mm you have a small field of vie but you zoom in the image.

More about it:
http://www.photoaxe.com/understanding-the-lens-focal-length-and-aperture/
http://en.wikipedia.org/wiki/Focal_length
Some focal lengths Comparison:
http://www.tamroneurope.com/flc.htm

 

[Markw]

Heh, someone will probably come along and correct me.... it's the distance, in millimeters, from the lens to the focal point, the sensor of the camera. So if I interpret that correctly, at 50mm, the lens it 50mm away from where the image is recorded. 400mm would be 400mm away (and explains the rather lengthy lenses).

50mm on a 35mm camera is roughly how the world looks without the camera.

At 400mm, things are going to seem a whole lot closer.

Ignore the text, but look at the pictures here: http://en.wikipedia.org/wiki/Photographic_lens#Aperture_and_focal_length

The 4 pictures labeled 28mm, 50mm, 75mm, and 210mm. They're taken from the same standing position, with lenses at different focal lengths.

They could not have used a worse structure to demonstrate this on if their life depended on it! I get the general idea but with the mostzoomed in one, you cant even tell where on the structure it is zoomed on. It could be anywhere there and it would make a difference if you knew. Just figured Id point that out.

Mark

 

[rufus5150]

It exists simply to illustrate (rather well) the difference, not a precision illustration of a specific mark at those focal distances. You can use the lake in the background as a reference if you must (hint: it's darker blue.).

 

[mudthirsty]

Here's a site I found when I was trying to learn this stuff. It helped explain it a bit better.
http://www.cambridgeincolour.com/tutorials/camera-lenses.htm