GUESS THE LENSES! (Sorry Ian, but you're disqualified.)


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YSLee

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#1


Guess the lenses! Those who get everything right will win....
































ABSOLUTELY NOTHING! MUHAHA!
 

Flare

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#3
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...
 

Kho King

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Jan 20, 2002
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#4
My Guess:

Nikkor 400mm f/2.8 IF-ED Manual
AFS 300mm f2.8
AFS 80-200mm
AFS 28-70mm
AFS 17-35mm
 

revenant

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#5
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...
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 :)
 

Kho King

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#6
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 :)
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.
 

revenant

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#7
Originally 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.
oh ok..thanx

2nd part i not very sure....
 

Flare

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#8
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.
 

revenant

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#9
Originally 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.
alright, thanx :D
 

Fred

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#10
Don't know about the biggest lens, but here's my take:

AFS 300mm f2.8
AFS 80-200mm f2.8
AFS 28-70mm f2.8
AFS 17-35mm f2.8
TC14E
TC20E
SB28DX
:cool:
 

Darren

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Jan 16, 2002
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#11
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......
 

Ian

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#12
Originally posted by YSLee


GUESS THE LENSES! (Sorry Ian, but you're disqualified.)

Guess the lenses! Those who get everything right will win....

Doh I wonder why??? :devil:

Koks YS over the noggin with a very heavy large lens of the f2 variety
 

Ian

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#13
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 :)
There's plenty of confusion about this issue so here goes a full and detailed account.

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.
 

Ian

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#14
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...
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)
 

rumraisin

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#15
OK, question: how does a lens achieve, say, a 200mm focal length if it's less than 200mm long?
 

Jed

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#16
It uses a telephoto design as opposed to a normal long focus design. Long focus designs have been extremely rare now for a long time, with a few designs still around generally for LF lenses, but all but extinct from 35mm designs.
 

poseidon

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#17
Originally posted by rumraisin
OK, question: how does a lens achieve, say, a 200mm focal length if it's less than 200mm long?
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. ;)
 

Lennier

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#20
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. ;)
To add to that, there's the DO (Diffractive Optics) technology that Canon has started to use on their tele primes.
 

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