will a 2x teleconverter double by optical zoom?


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naresh666

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#1
i have a s45. wanna know if a 2x teleconverter will double the optical zoom? and if i stack on will there be any quality loss?
 

roygoh

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#2
If your camera lens is 35~105mm, that is a 3X zoom (105/35 = 3).

When you attach a 2X teleconvertor, the effective focal length becomes 70~210mm. The zoom factor is still 3X (210/70 = 3).

The total range available to you, considering the camera lens with and without the 2X convertor, becomes 35~210mm, which is 6X.

The main difference between your setup versus one with a native 6X zoom lens is that you cannot zoom smoothly from 35mm all the way to 210mm. You'd have to attach and remove the 2X teleconvertor to get that kind of zoom range.
 

beeryguz

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#3
Sorry but can you please elaborate what you mean by "have to attach and remove the 2X teleconvertor to get that kind of zoom range". Thanks.

rgds.
 

naresh666

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#4
i think its like without the tc u range is within the 1 to 3x zoom. once u attach the tc u get 4 to 6 x zoom. but with the tc attached u cannot go back down to 1 to 3 x.
 

AReality

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#5
Aiya.. wat he actually means is

Without the TC,
U'll get 1x to 3x zoom

with the TC,
U'll get 2x to 6x zoom

since your s45 zooms by moving the switch at your index finger, each step of the zoom will be doubled.

Example:
means 1x, 1.5x, 2x, 2.5x, 3x
becomes 2x, 3x, 4x, 5x, 6x
 

stk

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#7
naresh666 said:
so will there be any quality loss?
The quality will depend on the TC u use.. it ranges from very bad to very good.. :)

Btw, with some TC u may not be able to enjoy full zooming due to vignetting. So while u may be able to shoot at 6x, u may get vignetting if u zoom out. Again, this depends on the TC u use.
 

chriszzz

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#9
In summary,

1. You will get loss of quality. A good TC will minimise this. Look out for abberations, softness and distortion at the edges and corners. Shoot a some shots in the shop and view them on your PC before commiting to buy it. A good shop will let your try it.

2. Since you getting a 2x, your focal range is 35-105 and 70-210 in theory.

3. But, some TCs vignette at wider angles, so realistically your range becomes 35-105 ( without TC ), and something like 180-210 with TC ( your mileage may vary ).

4. Its a cheap and worthwhile investment even with the above limitations. You can never have too much focal range :)
 

roygoh

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#10
A 35-105mm zoom lens is 3X, and a 70-210mm zoom lens is still 3X, even a 1000~3000mm zoom lens (if one exisits) is still 3X.

The number of "X" is to indicate the ratio between the max and min focal length of a zoom lens, it is not an absolute number.

And I did miss out the effect of vignetting. With the TC attached, there will be vignetting when the camera is zoomed out. So the usefull focal range with the TC attached will not be from 70~210, but more likely from 140mm~210mm.

The best thing is to forget about how many X you have, but just to look at the actual range you can achieve.

Without TC, you can zoom from 35mm to 105mm (3X).

With TC, your effective zoom range becomes 140mm to 210mm (1.5X).

Trying to quantify the overall zoom range by a single number of X is quite meaningless.
 

KSeet

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#11
roygoh said:
A 35-105mm zoom lens is 3X, and a 70-210mm zoom lens is still 3X, even a 1000~3000mm zoom lens (if one exisits) is still 3X.

The number of "X" is to indicate the ratio between the max and min focal length of a zoom lens, it is not an absolute number.

And I did miss out the effect of vignetting. With the TC attached, there will be vignetting when the camera is zoomed out. So the usefull focal range with the TC attached will not be from 70~210, but more likely from 140mm~210mm.

The best thing is to forget about how many X you have, but just to look at the actual range you can achieve.

Without TC, you can zoom from 35mm to 105mm (3X).

With TC, your effective zoom range becomes 140mm to 210mm (1.5X).

Trying to quantify the overall zoom range by a single number of X is quite meaningless.
Just something I always wanted to ask:

What's the practical meaning of focal length and range? My C730 has 10x zoom, so what is its length and range? How does it affect my photos? THanks!
 

B

Barnabas

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#12
hi
i also wanted to ask what the focal range is all about..i am not very sure,i have a c-750 with a 10x setting..i think it states that it is 6.3mm to 63mm,can i buy any optional lenses to increase the zoom distance?
 

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