oh ok.Originally posted by Flare
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...
35mm is not a zoom, but prime. Zoom means you can have different focal length. To understand how many x zoom, just divide the highest focal length with the lowest, eg. 28-300mm lens is a 10x zoom, 35-70mm is a 2x zoom.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..thanxOriginally posted by Kho King
35mm is not a zoom, but prime. Zoom means you can have different focal length. To understand how many x zoom, just divide the highest focal length with the lowest, eg. 28-300mm lens is a 10x zoom, 35-70mm is a 2x zoom.
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.
alright, thanxOriginally posted by Flare
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.
Doh I wonder why??? :devil:Originally posted by YSLee
GUESS THE LENSES! (Sorry Ian, but you're disqualified.)
Guess the lenses! Those who get everything right will win....
There's plenty of confusion about this issue so here goes a full and detailed account.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![]()
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.Originally posted by Flare
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....
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...
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.Originally posted by rumraisin
OK, question: how does a lens achieve, say, a 200mm focal length if it's less than 200mm long?
I don't exactly have the illustration for the camera lens, but here is an illustration of something similar in technology in a telescope:Originally posted by rumraisin
Hmm... can't visualise it. where does the mirror go?
To add to that, there's the DO (Diffractive Optics) technology that Canon has started to use on their tele primes.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.![]()