My Nikon lens zoom question... very easy!!

[snowman]

First, excuse me for being the epitome of "camera dummy". I love photography, but am hopeless at it. I occasionally get a brilliant shot, but otherwise, well, lets just say that digital cameras are a godsend because of the very useful "delete" button! ;)

A friend recently asked me what my optical zoom was on my new Nikon D70s DSLR camera. My lens is the Nikkor 18-70mm (1:3.5-4.5G) focal length, the "standard" that goes with the D70s, I think. My problem is I didn't know the answer! On my old simple point and shoot fuji finepix I knew that it had a total optical/digital zoom of 10x, and that sort of answer is what he was looking for, but I did not know how that translates in a DSLR. In short, I want to tell him, "my zoom is -- x". Can anyone help, and/or direct me to a good link to explain all this? I imagine it's easy for someone who knows cameras, but I'm lost.

Cheers, and happy new year!

[achuang]

It's very simple to find the optical zoom of your lens. All you need to do is divide the telephoto end of the zoom by the wide end of the zoom. eg. in the case of your lens it is 70/18 = 3.9x zoom lens.

Andrew

[snowman]

Andrew,
Thanks for the reply. However, it sounds like that is giving me the average zoom for my camera. I want to find out what the zoom magnification is when my lens is extended to 70mm. I.e., maximum zoom.

[K1W1]

You misunderstood.
Zoom is the ratio of the longest length (70mm) over the shortest length (18mm) therefore you have a 3.9x zoom lens.
To put it another way 70mm is 3.9 times longer than 18mm.
Magnification is a function of macro lenses and you do not have a macro lens.

[achuang]

All the camera manufacturers for point and shoot cameras use for example 3x zoom, usually optical. But they also give a 35mm focal length aswell usually 38-114mm or something close to that. The way it would work for your lens, let's just round off the 18-70mm lens as a 4x zoom lens. at 18mm you'd be a 1x zoom, at 36mm you'd be at 2x zoom, and so forth. Topping out at roughly 4x zoom at 70mm. Every camera's optical zoom is different as it depends on the wide angle and telephoto focal lengths of the lens. optical zoom is dependent on how wide and how telephoto the lens is where the 18-70 lens is a 3.9x zoom lens. There are also lenses such as a 70-300mm lens which has an optical zoom of 4.3x. As you can see both are roughly 4x zoom lenses, but it just depends on each end of the zoom range. Optical zoom (eg. 4x zoom) is a relative measurement, but 35mm focal length is absolute as you could be at the 4x zoom setting of a 18-70mm lens and it would not be able to fill the frame with distant objects. But at the 4x zoom setting of a 70-300mm lens you still have the same optical zoom but is a lot more telephoto. Hope it helps

[Rooz]

or better still, tell your mate you have a 70mm lens and that he should get a real camera. :D

[snowman]

Ha! Nice "get a real camera" comment for my friend! And thanks for the detailed explanation. Incidentally, I also have a Nikkor 75-300 (1:4.5-5.6), so the extra info about telephotos has already answered my next question. Time to do some comparative zooming between the two lenses.

Cheers!

[Pyrex]

I personally understand all the elements of zoom, but your 18-70mm lense doesn't really zoom actuality, open up both eyes and zoom it all the way in... you'll notice theres no zoom, its exactly the same as your eye.

[rawpaw18]

As stated a previous post, the 18-70 zooms 3.9x. The only lenses that do not zoom are primes. The fact that it may have the same view as what you see with your eyes does not take away the fact that it does zoom. Zoom has only to do with the fact that the range changes, it does not matter where it starts or stops.

[shingfan]

for 18-70mm lense...the zoom is 70/18 = 3.9x zoom....for a different lense with 70/200...the zoom is 200/70 = 3x zoom.....the zoom factor is the range of operation of your lense........not how much you can magnify the image.......like when you are viewing a picture on a picture view....you have zoom fuction.....assuming that 18mm is 100% zoom....then 70mm would be equal to a 390% zoom...and that is the ZOOM capability of your lense.....if i understand it correctly......ZOOM is not how much you can fit in your picture.....is only the operating range of the lense on the camera......you can have prime lenses with different focal length.......compare a 50mm prime to a 100mm prime.....at the same shooting location for the same scene.....you can fit a lot more with 50mm....however....both lense have no ZOOM factor as they are prime lense......i hope this clears up your cloud.....ZOOM is often misunderstand as a magnifying factor but it is not.....it is operating range from min. to max (ratio between min and max)

[Rooz]

aren't we getting a little pedantic here ? zoom is zoom. if you have your 18-70mm lens opened out to 18mm and you want to get closer, you ZOOM into the object up to the maximum of 70mm. to the average bloke on the street, thats called a zoom.