mm please help me understand

V

visitorq

Suspended / Banned
Messages
16
Name
2a
Edit My Images
Yes
Hi everyone

this may wel and truly be the dumbest thing anyone can ask but as a beginner i am still trying to understand the mm on the lens...

Iv read some stuff myself and still dont really get it..sounds like complicated mathematics...

I was wondering if anyone could break it down in simple forms...

How does the mm in a lens work? How does it work with the fstop and do you need it set at a certain number to work with your other settings?

sorry for sounding dumb!
any help would be great or a link to a dummy site :'(
 
I think the mm is the actual length of the lens, correct me if im wrong i.e a 300mm lens is 300mm long.
 
VisitorQ

No question is dumb if you do not know the answer.

I take it you are referring to the mm as in 50mm or 70mm that sort of thing?? if so then that is the focal length of the lens, you can get prime lenses which are a fixed length like 28mm - 50mm - 85mm and so on then you can get you zoom lenses 18mm- 70mm and so on.

The F Stop is the aperture of the lens which basically mean how much light you are letting in to the camera. This also controls what is called the depth of field (This is if the background of the image is sharp like the main subject or blurred) The thing that will seem strange to you is the small the number lets say ƒ2.8 lets in lots of light and blur's the back ground where as the large number say ƒ22 lets in less light and makes the image sharp (In focus) front to back.

I do not know if you have a DSLR or not but I would suggest sticking the camera on Aperture priority and going out for the afternoon and practicing what effects you get when you change the aperture, you will also be able to see the relationship between the F-stop and the shutter speed. Your shutter speed will get slower the less light you have.

Hope this helps a little.


Nigel
 
Ok

Yes I have a 400d (entry level) and I have two lenses sigma 17-70mm f2.8 - 4.5 and a nifty fifty

I understand the effects of the fstops i was just wondering about the mm and yes i do mean the mm in the 50mm, ok so it is the focal length ...

mmmmmmm well i am experimenting today..reading seems to make it more difficult i guess ill just put it into practice...

thanks for the replies
 
visitorq said:
Ok

Yes I have a 400d (entry level) and I have two lenses sigma 17-70mm f2.8 - 4.5 and a nifty fifty

I understand the effects of the fstops i was just wondering about the mm and yes i do mean the mm in the 50mm, ok so it is the focal length ...

mmmmmmm well i am experimenting today..reading seems to make it more difficult i guess ill just put it into practice...

thanks for the replies
Click to expand...

Not a problem the 17-70 will give you a nice focal range from wide to mid zoom length. After a while you can get lost in the reading of manuals. I would say go and have some fun with the camera and read small sections of the manual every nice until suddenly that little light bulb will go off in your head and it will all click.

Remember you have your full auto mode and your other modes have a play with them all so you start to understand what the camera can do.

Good luck

Nigel
 
:agree:

Don't get bogged down with technicalities at the moment, that can come later. Just read the cameras manual so you know what the main settings on the camera mean and go out and have fun. Experiment with different apertures on the same subject that you are photographing and see the difference it makes when back at home.

If you are purchasing magazines then what i do is find a pic in the mag that has the camera settings printed, (shutter speed, aperture, ISO etc) that could be similar to something you could shoot like a tree in a park and use the same settings as the pic in the mag. It probably won't be right but it's a starting point. Just keep taking pics using different settings and see what you get.

When you get back home open the images (Raw Files are best) as you will be able to right click on the image and bring up all the camera info so you can find the good ones and see the settings for future reference.

It's like juggling, hard at 1st but does get easier as time goes on.

Good luck and have FUN FUN FUN!!
 
50mm is standard - what you see is what you get.
Anything more, and you're into telephoto territory - magnifies the image
Anything less, it's wide angle - can fit more into the picture. Try it!
 
foodpoison said:
50mm is standard - what you see is what you get.
Anything more, and you're into telephoto territory - magnifies the image
Anything less, it's wide angle - can fit more into the picture. Try it!
Click to expand...

by standard, FP means what your eye normally sees;)
 
Forbiddenbiker said:
Except of course, 50mm on a cropped sensor like the 400d (x1.6) is actually and effective focal length of 85mm ish.... so its no longer a standard view, but has now become a magnified view.
Click to expand...
It can get confusing....
When looking through the viewfinder, the 1.6x crop factor does not "magnify" anything, it simply reduces the field of view (similar to tunnel vision). A 50mm lens on a crop body will still give the same subject size as perceived by the naked eye.

Bob
 
Very true.... but haven’t you just now made it more confusing for the OP Bob.

Inevitably, using a 50mm on a cropped body will give you... effectively an image which looks magnified. This is because in normal use, no person would decide to get take the subject at the same size as they would on a non cropped body just because they wanted to keep the focal length the same ...No, I think not.. they'd move their feet backwards and re-frame so as not to cut the bottom and top off and in doing so they have a magnified image.


I reckon. :)
 
so a 30 or 35mm lens on a crop body gives you the naked eyes field of view then?
 
The crop sensor magnification myth will never go away as long as the manufacturers of point and shoot cameras continue to describe the focal lengths of the lens incorrectly in their sales hype.
 
visitorq said:
Hi everyone

this may wel and truly be the dumbest thing anyone can ask but as a beginner i am still trying to understand the mm on the lens...

Iv read some stuff myself and still dont really get it..sounds like complicated mathematics...

I was wondering if anyone could break it down in simple forms...

How does the mm in a lens work? How does it work with the fstop and do you need it set at a certain number to work with your other settings?

sorry for sounding dumb!
any help would be great or a link to a dummy site :'(
Click to expand...

to make things nice and simple the 50mm on a 50mm lens means the element is 50mm away from the sensor - you dont really need to worry about this what you need to know is the lower the number in mm the more field of view you get, the longer the number the more far away objects will appear closer.

HTH
 
Thanks for all the responses guys...
Some of the links have helped .. I think I kinda grasp the basics but I guess more practice helps...

Im gonna be brave and post some images up soon and would like some advice...tbc...
 
You must log in or register to reply here.
Back
Top