magnification

[pikeman1960]

hi all at the moment i have a compact and it says 6x optical zoom ,but changing shortly to dslr but am confused by lenses being in mm how do you no what you are buying: as in magnification

 

[Chris Primadona]

It really depends on what the standard lens magnification was unzoomed. The "6x" can mean anything tbh.

 

[Nawty]

Take a standard kit lens, say 18-55mm.

55/18=3, so that's a 3x zoom.

However, 3x zoom doesn't really mean anything at all unless you know the field of view that gives, i.e. the mm (you also need to konw the sensor size but that's not important right now).

Compared to the 18-55 (when used on most DSLRs), you camera probably goes from 35-210mm, or maybe 28-168mm so what you typically get with the kit lenses is more wide angle, less 'zoom' as you would probably call it (that's not really the correct term but never mind).

 

[Photodiva]

Compacts and DSLRs are totally different. The 'chip' in a compact can be as tiny as your little fingernail, those in DSLR's are much bigger, but usually a bit smaller than the old 35mm film (termed 'full frame'). When you buy a lens for a dslr you have to do a bit of mental 'rithmetic, usually multiply by 1.6x for direct comparison with a 35mm film lens. Generally anything under 35mm is a 'wide-angle', between 35-100mm is 'standard' and 100mm+ is telephoto, so an 18-55mm which is often the standard 'kit' lens will be adequate for most general purposes. Its only when you begin to specialise that you may want specific lenses for, say, macro, or super zoom for wildlife etc.

There is no 'digital zoom' with dslrs, for which we can all be thankful.

 

[woof woof]

There's nothing wrong with digital zoom. It's really just a form of in camera cropping and people crop all the time... in fact... digital zoom would be quite a nice option when you're going to use the direct print button

As "DSLR's" slowly ditch their moving parts and move towards being purely digital digital zoom may well be an option, and no doubt there'll be an "off" option in the menu for those who don't wish to use it.

The key is to know what digital zoom is and then you can decide if / when to use it.

 

[roseway]

It's going to be a long time (if ever) before in-camera digital zoom equals the quality which you can get from cropping in post processing.

 

[HoppyUK]

It's going to be a long time (if ever) before in-camera digital zoom equals the quality which you can get from cropping in post processing.

Why? New Sony a77 has a built in Smart Telecon feature which can crop 1.4x or 2x and shows the magnified image in the electronic viewfinder. Why should that be any different to cropping post? Both methods throw away tons of quality - 1.4x uses half the sensor and 2x only a quarter of it.

To the OP, what you need to do is establish what your current camera has in terms of '35mm (full frame) equivalent focal range' which will probably be something like 28-160mm, then using the crop factor of the DSLR convert that to the new format.

Sounds complicated but it's not really. Tell us what you've got and what you're getting and someone will do it for you.

 

[specialman]

It's going to be a long time (if ever) before in-camera digital zoom equals the quality which you can get from cropping in post processing.

Been doing that on my D2x with the (x2) high-speed crop mode for years. Unless you looked at the pixel dimensions, you'd never be able to tell, and I'd put money on that.

Obviously, there is a point where the zooming in via a crop exceeds how well the lens can performs, but on larger sensor sizes where there's not as much pressure on the lens to perform, i can see the benefits. Using a 200mm lens but want effective 600mm? Done, and the image can be emailed straight off the card instead of having to go through PP. Cropping is cropping, simples....

 

[artyman]

As already said a 6X zoom is just the ratio between the shortest and longest focal length of the lens. My standard lens is 15-85 which in compact terms is 5.66X yet my telephoto which is 150-500 would be 3.33X both those figures is only an indication of the range of a particular lens, the focal length is what really matters. My telephoto at 500mm is what I use for shooting birds, indoors 15mm is more useful.

 

[NikkiA]

Many compacts and bridges still record the 35mm equivalent of the lens in their EXIF. So if yours does, you can easily get a feel for the equivalent lenses you'd need/use on a dSLR, just take photos at each extreme of the zoom and note the value from the EXIF.

 

[Scarecrow]

The 6x, 8x,10x etc is just a selling point used to market compact cameras to people who know nothing about photography, but believe in the hype of the bigger the number, the better. The numbers only refer to a comparison of the focal length of the lens at either end of it's ability. Without knowing what the focal length is at either the wide end or telephoto end, the 6x or whatever is pretty meaningless.

In DSLR terms, for example, you could have a 20-100mm zoom lens, and a 100-500mm zoom lens. In compact parlance, both are 5x but other than that, they would be like chalk and cheese.

In old 35mm film days, a 50mm lens was considered standard, and was supplied with most new cameras. In simplistic terms anything shorter than that was considered wide angle and anything longer was considered telephoto. If you were to take several photos from the same viewpoint, a wide angle lens would allow you to capture more of the scene, as it has a wider field of view. Conversely, a telephoto lens would capture less, allowing you to hone in on a specific part of the scene, a bit like looking through a pair of binoculars.

If we accept a 50mm lens as being a standard of some sort, it makes it easier for us to imagine what lenses of other focal lengths will give us; a 500mm would be 10x whereas a 24mm would be roughly 1/2x. I know purists will probably frown on this notion, but for a novice who has no concept of what different focal lengths expressed in mm actually mean it's as good a place to start as any.