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Zoom vs lens size
Apr 22, 2013 09:34:08 #
Apr 22, 2013 10:53:43 #
Brendalou1969 wrote:
Ok, I see these point & Shoots that say they have a 20x zoom, what does that mean in context compared to a lens? I have a 200mm lens, does a 20X reach a farther distance? I just don't get it. Please help me understand.
Jimmy
Best Answer - Chosen by Voters
20X is not magnification. Your 20X camera is not the equal of a 20X telescope/binocular. What the 20X means is the difference between two different focal lengths used by the same lens. For example, a lens that is 5mm-100mm is 20X and a lens that is 10mm - 200mm is also 20X. The difference is that the 200mm focal length gives you greater magnification than the 100mm. At the same time, the 5mm focal length would give you a wider view that 10mm. So even though they both have 20X, they are not the same. Conversely, a lens with a focal range of 25mm -100mm would be only 4x, but get you as close (the same magnification) as the 5mm-100mm lens.
Apr 22, 2013 10:59:31 #
Wow, it seemed to be such a simple question, but there are many thoughts on just what exactly the difference is practically speaking.
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Apr 22, 2013 11:51:50 #
This scale, 20X zoom or 40X zoom etc. is just some salesman number invention to make certain cameras attractive to customers who do not know much about cameras.
If we use this method for dslr gear the nikon 18-300 lens on a dx camera would equal ca. 17X zoom, but if you add a 10-20 lens to your gear you would have 30X zoom, and if we talk about FX format cameras and have lenses from 14 mm to 500 mm then I would have almost 36X zoom. But if I would use the 500 mm lens on DX camera and also have a 10 mm wide lens for that camera then I have approx 75X zoom (because the lens equals about 750 mm on DX). But there is actually nothing gained with 75X zoom over 36X, the sensor size makes 36X zoom on full frame about equal to 75X zoom on the DX camera. And actually when you zoom in to 500 mm with 36X FX zoom then you get bigger picture than if you use DX with the same lens. So you really can get more with 36X zoom then 75X zoom.
Conclusion?
The 20X zoom is not telling much unless you have much more info like others have mentioned, about start and end point of the zoom range. And you must calculate for the sensor size as well.
If we use this method for dslr gear the nikon 18-300 lens on a dx camera would equal ca. 17X zoom, but if you add a 10-20 lens to your gear you would have 30X zoom, and if we talk about FX format cameras and have lenses from 14 mm to 500 mm then I would have almost 36X zoom. But if I would use the 500 mm lens on DX camera and also have a 10 mm wide lens for that camera then I have approx 75X zoom (because the lens equals about 750 mm on DX). But there is actually nothing gained with 75X zoom over 36X, the sensor size makes 36X zoom on full frame about equal to 75X zoom on the DX camera. And actually when you zoom in to 500 mm with 36X FX zoom then you get bigger picture than if you use DX with the same lens. So you really can get more with 36X zoom then 75X zoom.
Conclusion?
The 20X zoom is not telling much unless you have much more info like others have mentioned, about start and end point of the zoom range. And you must calculate for the sensor size as well.
Apr 22, 2013 12:30:46 #
lporrel
Loc: California
Digital zoom can be somewhat better than just cropping as the camera meters and focuses on just the bit that you are zooming in on.
mikemilton wrote:
The other consideration is if this is optical or digital zoom or both. Digital zoom (which is quite laughable really) is just cropping
Apr 22, 2013 14:17:10 #
Apr 22, 2013 17:57:11 #
The Canon powershot SX50 HS has a 50X optical zoom. The actual focal range is from 4.3mm to 215mm (50X). Taking the sensor size into account, this equates to 24mm to 1200mm on a full-frame (35mm) camera. The digital zoom takes this in stages to 200X (equivalent to 4800mm) though the results at that extreme are pretty awful.
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Apr 22, 2013 19:34:06 #
[quote=Uuglypher]A 20X prime lens on a full-frame sensor = "normal" focal length (50mm) x 20 = 1000mm.
re-read her question! a point and shoot camera she said. no full frame!
re-read her question! a point and shoot camera she said. no full frame!
Apr 22, 2013 20:10:34 #
[quote=elie]
Captain C is correct - the "20X" is for advertising purposes mainly, and has very little comparative value. Look on the barrel - they show the "Lens" length. My SX30 zooms from 24 mm to 840 mm.
**This is AFTER the crop factor is applied**
Uuglypher wrote:
A 20X prime lens on a full-frame sensor = "normal" focal length (50mm) x 20 = 1000mm.
re-read her question! a point and shoot camera she said. no full frame!
re-read her question! a point and shoot camera she said. no full frame!
Captain C is correct - the "20X" is for advertising purposes mainly, and has very little comparative value. Look on the barrel - they show the "Lens" length. My SX30 zooms from 24 mm to 840 mm.
**This is AFTER the crop factor is applied**
Apr 22, 2013 21:28:30 #
JPL wrote:
This scale, 20X zoom or 40X zoom etc. is just some... (show quote)
I know just a little bit about cameras and this is the most confusing nonsense I have ever read - and on this site that is saying something. Sensor size has NOTHING to do with a zoom range. 3X, 5X, 23X does not matter. All it is is a multiplier of the widest FOV.
Go ahead - berate me. I don't care. Bad information is still bad information.
Apr 22, 2013 22:01:59 #
CaptainC wrote:
Go ahead - berate me. I don't care. Bad information is still bad information.
Go ahead - berate me. I don't care. Bad information is still bad information.
The post to which you refer (and others like it) makes me wish there were a way to "like" or "dislike" the information here on the hog.
...but then, does the person doing the rating get rated?
Apr 22, 2013 22:35:23 #
Uuglypher wrote:
A 20X prime lens on a full-frame sensor = "normal" focal length (50mm) x 20 = 1000mm.
A 20X zoom RANGE would refer to 1000mm. on top of its focal length at the widest of it wide-angle setting.
Are you dealing with a full-frame sensor or a "crop-factor" (smallr) sensor?
A 20X zoom RANGE would refer to 1000mm. on top of its focal length at the widest of it wide-angle setting.
Are you dealing with a full-frame sensor or a "crop-factor" (smallr) sensor?
:thumbup: Yup! Works the same for binoculars and spotting scopes as well. That is why he stated with a full frame.
Why not just pick up the camera and look through the viewfinder and zoom it in and out. If it will work with the subject matter you want to take, and has the features and price you want, who cares what the numbers are?
Apr 22, 2013 22:43:11 #
Bozsik wrote:
:thumbup: Yup! Works the same for binoculars and spotting scopes as well. That is why he stated with a full frame.
Why not just pick up the camera and look through the viewfinder and zoom it in and out. If it will work with the subject matter you want to take, and has the features and price you want, who cares what the numbers are?
Why not just pick up the camera and look through the viewfinder and zoom it in and out. If it will work with the subject matter you want to take, and has the features and price you want, who cares what the numbers are?
OK. I give up. Full frame, crop frame, A frame. These have nothing....oh never mind. This is like talking to a stone.
Apr 22, 2013 23:01:37 #
CaptainC wrote:
OK. I give up. Full frame, crop frame, A frame. These have nothing....oh never mind. This is like talking to a stone.
CaptainC You usually have an understanding for most of these issues, but you getting a bit frustrated with this one.
Before cropped sensors and other cameras, the image from the 50mm lens was the standard for magnification of images. It also applied to the the power of binoculars ( and still does) as well. If you have a 8 power pair of binoculars, it will be approximately the same magnification as a 400mm lens. With the advent of all the new formats, you can't use the magnifying power any more because some of it is done digitally, not optically, and some is done via a different size sensor, etc. The only way to accurately determine the magnification is if you have the full frame sensor and someone says that the power is such and such, you can then find the equivalent focal length in mm.
I still go with the idea of not asking someone what focal length I need, but just attaching the different lenses to the camera and looking through the darn thing. If it provides the field of view you require, go with it.
Apr 22, 2013 23:15:19 #
mfeveland wrote:
Jimmy br br br br Best Answer - Chosen by Vot... (show quote)
That is why the standard was based on the full frame format @ 50mm. There is no standard any more to work from. That is why so many are confused.
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