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The lens is definately heavier...some can weight few kilos..
For the mater a bright 200mm lens can weigh more than a film SLR body. I cannot recognise the lens....
Revenant, one thing... Don't look at the how many x zoom... Look at the focal length, if its a digital camera, the equivalent focal length. This tell you how much 'enlargement' you can get. let's say my Minolta D5, has a zoom lengths with 35mm to 250mm equivalent focal length, which is about 7x optical zoom (250/35 is about 7). A prime 600mm lens has a focal length fixed at 600mm.. so effectively its 1x lens... But it has a bigger 'enlargement' maybe can even see your pimple where my camera can see your face...
For the mater a bright 200mm lens can weigh more than a film SLR body. I cannot recognise the lens....
Revenant, one thing... Don't look at the how many x zoom... Look at the focal length, if its a digital camera, the equivalent focal length. This tell you how much 'enlargement' you can get. let's say my Minolta D5, has a zoom lengths with 35mm to 250mm equivalent focal length, which is about 7x optical zoom (250/35 is about 7). A prime 600mm lens has a focal length fixed at 600mm.. so effectively its 1x lens... But it has a bigger 'enlargement' maybe can even see your pimple where my camera can see your face...
Originally posted by revenant
oh ok.
Meaning 35mm is 1x zoom right? Some cameras/lens never state how many x zoom but we can tell from the focal length?
thanx
oh ok.
Meaning 35mm is 1x zoom right? Some cameras/lens never state how many x zoom but we can tell from the focal length?
thanx
Fixed focal length lens has only one focal length, thus you can't say how many x zoom it has...as it is not a zoom at after all.
Prime lens. which I believe the two big buggers there are, cannot zoom... they have one fixed focal length (enlargement)... These are called prime lens.
35mm is not 1x zoom... some digital camera starts at 28mm some at 38mm... divide the highest focal length by the lowest to get the optical zoom. Look at the detailed specification for the equivalent focal length of consumer digital cameras.
35mm is not 1x zoom... some digital camera starts at 28mm some at 38mm... divide the highest focal length by the lowest to get the optical zoom. Look at the detailed specification for the equivalent focal length of consumer digital cameras.
Nikkor 400f/2.8 ED AIS Manual
AFS Nikkor 300f/2.8 IF-ED
AFS Nikkor 80-200f/2.8 IF-ED
AFS Nikkor 28-70f/2.8 IF-ED
AFS Nikkor 17-36/f2.8 IF-ED
Nikkor TC20E (or EII version)
Nikkor TC14E (or EII version)
SB28DX
Nikon F5
Nikon D1 body - can't tell if its D1, D1H or D1X
*sigh* my two dream lenses (400f/2.8 and 300f/2.8) - so near and yet so far......
AFS Nikkor 300f/2.8 IF-ED
AFS Nikkor 80-200f/2.8 IF-ED
AFS Nikkor 28-70f/2.8 IF-ED
AFS Nikkor 17-36/f2.8 IF-ED
Nikkor TC20E (or EII version)
Nikkor TC14E (or EII version)
SB28DX
Nikon F5
Nikon D1 body - can't tell if its D1, D1H or D1X
*sigh* my two dream lenses (400f/2.8 and 300f/2.8) - so near and yet so far......
Originally posted by revenant
oh ok.
Meaning 35mm is 1x zoom right? Some cameras/lens never state how many x zoom but we can tell from the focal length?
thanx
oh ok.
Meaning 35mm is 1x zoom right? Some cameras/lens never state how many x zoom but we can tell from the focal length?
thanx
Firstly a prime lens is a lens of fixed focal length, for example 13mm 55mm, 200mm 600mm and so on.
A zoom lens has a variable focal length between two paramaters, a minimum focal length and a maximum focal length. eg: 20-105mm, 28-70mm and 80-200mm, 50-500mm etc.
Zoom Ratio
The optical zoom ratio (x zoom) is calculated by dividing the maximum focal length by the minimum focal length, eg:
500/50 = 10 therefore it's a 10x zoom
200/80 = 2.5 - so it's a 2.5x zoom
Note: The Zoom ratio is NOT the same as a lenes magnification ratio.
Magnification
A lenses magnification is not the same as it's Zoom Ratio.
A lenses magnification can be caluculated in two ways.
M = I/S
where;
M = magnfication
I = Image Height on film
S = Subject height in real life
OR
M = magnfication
I = Image distance between front of lens and film plane
S = Distance from front of lens to the subject.
Image scale and magnfication can also be measured, however I'm not going to discuss the methods used as it's fairly complex and requires a good grasp of lens and optical theory.
A fast 200mm f2 lens weighs in at around 2.5 kg, roughly 3 times the weight of the average amateur film SLR and is of comparable weight to a 300mm f2.8 lens.
Let's see the heaviest lens I know from Nikon weighs in at a light 17.5kg .. now that's surely more than a few kilos is it not?
(see my post above post for more information)
Let's see the heaviest lens I know from Nikon weighs in at a light 17.5kg .. now that's surely more than a few kilos is it not?
(see my post above post for more information)
Just trying to answer thru common sense (physics). Actually u just need a 'virtual' focus distance. It means 200 mm focal length not necessary need 200 mm lens distance, this can be halfed by mirror or lens that act a mirror. So the achieved distance will be doubled the actual distance. Well, this method has a drawback of losing light, but with some technology of lense this lost can be reduced.
I don't exactly have the illustration for the camera lens, but here is an illustration of something similar in technology in a telescope:
http://www.howstuffworks.com/telescope4.htm
http://www.howstuffworks.com/telescope4.htm
Originally posted by poseidon
Just trying to answer thru common sense (physics). Actually u just need a 'virtual' focus distance. It means 200 mm focal length not necessary need 200 mm lens distance, this can be halfed by mirror or lens that act a mirror. So the achieved distance will be doubled the actual distance. Well, this method has a drawback of losing light, but with some technology of lense this lost can be reduced.
Just trying to answer thru common sense (physics). Actually u just need a 'virtual' focus distance. It means 200 mm focal length not necessary need 200 mm lens distance, this can be halfed by mirror or lens that act a mirror. So the achieved distance will be doubled the actual distance. Well, this method has a drawback of losing light, but with some technology of lense this lost can be reduced.
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