Please explain the difference...

[Michele]

...between a Zoom lens and a Telephoto Zoom lens.


I'm afraid this is a really stupid question, and it's probably one that I could research myself and find the answer but my friends here on the Disboards are so helpful and explain things so well.

Thanks so much!

 

[Master Mason]

A zoom lens is any lens that has a variable mm rating. ie 10-24 24-40, 18-200 etc.

A telephoto zoom is one that is constructed so that the optical center is outside the lens. The optical center is the distance where the focus of the various points occur. So a 50mm lens focus occurs at 50mm from the plane of the sensor. On a 200mm the focus occurs 200mm from the plane of the sensor. If that ocurs outside the lens, then it is a telephoto lens. At least that is my understanding.

 

[Groucho]

I think that in common usage, there are "wide zooms" and "telephoto zooms" - wide being the usual 18-55mm or 28-75mm range and telephoto being 50-200mm, 75-300mm, etc. Then there's ultrawides, like 10-20mm or 12-24mm...

Unless you really interested in the minutia of lens design, you can probably safely (and correctly) just refer to all of them as "zoom lenses" if they have multiple focal lengths, and "prime lenses" if they have a single focal length.

 

[Michele]

So zoom means the focal length is variable, as in, not a prime lens. And telephoto zoom means it has a far reaching focal length. Does that sum it up correctly?

 

[Groucho]

Yeah, but if you are going to use the term "telephoto zoom" you also have to use "wide zoom" when talking about those. Both are zooms, just covering different focal lengths. Generally you're safe just saying "zoom lens".

 

[DizzyV6P]

I wouldn't get too hung up on the wording. Just post up what type of lens you have questions about (e.g. 70-200, 17-55, 28-75, etc...) and I'm sure plenty of folks here can help you out.

 

[Master Mason]

Telephoto has a specific meaning. You can have a telephoto prime.

In the over all scope of things it means absolutely nothing to the end user. It is simply the way that lenses with greater magnification need to be built so they don't end up 3 feet long.

Worry about the zoom range, worry about the f values in that range. If it is a telephoto or not doesn't make a bit of difference to how it performs.

 

[seashoreCM]

Telephoto zoom lens -- zoom lens some or all of whose range gives a (telephoto) view narrower than the "standard view angle". The latter is nowadays said to be between 35 and 50mm in terms of focal length for a 35mm film camera. Modern point and shoots tend to have a standard view based on a 38mm (give or take) focal length lens for 35mm film while traditional SLR and older large format cameras tend to have a standard view equal to a 50mm focal length lens and 35mm film.

I don't think there is any different terminology for a lens that is constructed so the barrel length is shorter than the actual focal length (the optical center being outside the lens).

Note that the same lens could be a wide zoom on one camera and a telephoto zoom on another. Because the sensor size is different for different cameras, a different view angle will be captured when a given lens is moved from one camera to another. (The lens is still projecting the same image into the camera body.) When the lens was originally meant for a 35mm film camera, you take 43-1/4 and divide by the sensor diagonal and multiply the focal length(s) by this (the crop factor for that camera) to get the 35mm film camera focal length(s) for the new lens and camera combination.

You need to be careful about using a short barrel digital camera lens (shorter than the focal length) on an actual 35mm camera. Such lenses may be stamped with 35mm equivalent focal lengths but their sweet spots may be smaller than a 35mm film frame resulting in blurry or vignetted edges and corners.


Digital camera hints: http://members.aol.com/ajaynejr/digicam.htm

 

[Master Mason]

Telephoto zoom lens -- zoom lens some or all of whose range gives a (telephoto) view narrower than the "standard view angle". The latter is nowadays said to be between 35 and 50mm in terms of focal length for a 35mm film camera. Modern point and shoots tend to have a standard view based on a 38mm (give or take) focal length lens for 35mm film while traditional SLR and older large format cameras tend to have a standard view equal to a 50mm focal length lens and 35mm film.

I don't think there is any different terminology for a lens that is constructed so the barrel length is shorter than the actual focal length (the optical center being outside the lens).

Note that the same lens could be a wide zoom on one camera and a telephoto zoom on another.

I'll have to disagree with you here

In photography and cinematography, a telephoto lens is a specific construction of a long focal length photographic lens that places its optical centre outside of its physical construction, such that the entire lens assembly is between the optical centre and the focal plane. A regular lens of a focal length that is longer than what is considered a normal lens is not necessarily a telephoto lens. A telephoto lens has to incorporate a special lens group known as a telephoto group (see below); nevertheless, non-telephoto lenses of long focal length are often informally referred to as telephoto lenses. The angle of view created by a telephoto lens is the same as that created by an ordinary lens of the same specified focal length.

If you go here http://www.usa.canon.com/consumer/controller?act=ProductCatIndexAct&fcategoryid=111 it will show you that there are zooms, telephoto zooms, lenses, and telephoto lenses. It has to do with the construction of the lens not the focal lenght, or the effective focal lenght.

But again, to the end user it makes not a bit of difference

 

[mabas9395]

I did not know that. Another useful (ok, not really useful but still interesting) piece of info that I can share on other photo boards when I'm indoors talking about photography when I should be outside actually taking pictures.