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Old Sep 21, 2010, 2:38 AM   #1
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Default Understanding the zoom of a lens

I have come from the world of point and shoot with the '** x zoom' so having a dSLR I don't understand how much zoom I will get.

I currently have the 14-42mm kit lens but I am looking at getting the 40-150mm lens. How much extra will that give me? what would its equivalent times zoom be on a point and shoot?

Sorry for the ignorance but lenses confuse me!
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Old Sep 21, 2010, 3:54 AM   #2
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150mm will get you about 3 1/2 times closer than your 14-42 at 42mm. In 35mm film a 150mm would be a 3 power lens. On a 4/3rds camera it's a 6x lens because of the crop factor. (it really isn't it' just the image is using only half the field of view so what you see is in effect doubled). It's late here so i hope i haven't just confused you.

To confuse you more zoom lenses are rated by the ratio of the zoom. That is, a lens that zooms from 100-300 will be considered a 3x zoom because the long end is 3x's the short. Or a 28-200 is considered a 7x zoom. The same applies to point and shoot cameras as well. When they talk of having a 10x zoom they just mean it's the equivalent to a 20-200 lens or something like that. The lens at it's longest will get you 10x's closer than at it's widest but it's widest is going to be less than equivalent to 50mm in 35mm film cameras which is the standard for 1 power. In other words you'll be 10 times closer but you may not be getting as close as if you had a 10 power set of binoculars. 10x does not equal 10 power when talking about zooms.

Okay, the longer the lens (larger mms) the closer it will get you to the subject. That's all you really need to know. Oh, and that the longer the length the more camera shake will effect the image.

John

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Old Sep 21, 2010, 4:12 AM   #3
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Yes it confuses me but I think I get it. The lens is not that expensive so from what you have said it will be worth it.

Thanks!
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Old Sep 21, 2010, 5:42 AM   #4
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Quote:
Originally Posted by Thunderchild View Post
I have come from the world of point and shoot with the '** x zoom' so having a dSLR I don't understand how much zoom I will get.

I currently have the 14-42mm kit lens but I am looking at getting the 40-150mm lens. How much extra will that give me? what would its equivalent times zoom be on a point and shoot?

Sorry for the ignorance but lenses confuse me!
To add to John's explanation, what you will see in an image from a digital camera depends both on the focal length of the lens and the size of the sensor. P&S sensors typically are smaller than DSLR sensors (to keep the price down). To equalize all this, when manufacturers give the specs of a P&S lens they often give the "35mm equivalent" focal range, and this equivalent includes the conversion accounting for the difference in the sensor size versus the size of a "full frame" sensor (i.e 35mm film size).

As John said, the 4/3 sensor is half the size of a FF sensor so the 35mm-equivalent focal range of a zoom lens on a 4/3 camera will be doubled. Look at the specs of your P&S - it should state the 35mm equivalent focal range of the lens you were used to using. That should give you an idea of what to expect from your new camera's lenses.

Ted
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Old Sep 21, 2010, 8:10 AM   #5
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Quote:
Originally Posted by Thunderchild View Post
I have come from the world of point and shoot with the '** x zoom' so having a dSLR I don't understand how much zoom I will get.
"X" factors like 5X and 10X are only a marketing term and not a photographic term...it was invented by marketers to make their camera sound better than others. It's the difference between the widest position and zoomed in position on the lens.


It's calculated by dividing the highest telephoto focal length by the lowest wide angle focal length. To plug in the lenses you have, 42/14=3x, and 150/40=3.75x. If you take the two lenses together, you have a combined range of 150/14=10.7x.


The idea was people would be more impressed if they say they have a 15x lens, like the Tamron 18-270mm...but more experienced photographers know LESS "X" is better, and some use a 1x lens that has a fixed focal length (called a "prime" lens), like a 50mm or a 105mm lens!


Here's why "X" is meaningless...a lens that's 18 to 55mm is 55mm/18mm=3x zoom, but a 100-300mm lens is 100mm/300mm which also equals 3x zoom...but these are totally different lenses, one being wide to normal, and the other being telephoto to ultra-telephoto.


It's best you get to know how the focal length measurement in "mm" affects the image...play with this site (make sure you're set to 35mm and NOT digital; btw Tamron DOESN'T make lenses for FourThirds, but this is such a great tool for learning):
http://www.tamron-usa.com/lenses/lea...comparison.php


Note that the site is using 135/35mm camera equivalents, so you have to divide the number in MM by two to get the FourThirds focal length...if you select 50mm there the FourThirds equivalent lens in mm would be 25mm.

When comparing different cameras, 135/35mm camera format is used so we all have a common frame of reference. You didn't mention which P&S or bridge camera you used to use, but you can look up what the 35mm equivalent was (or if you can't find it, give us the model number and we can give you both the 35mm equivalent, and the FourThirds equivalent focal lengths). For example my Olympus C-700 the actual focal length was 5.9-59mm, but it had an equivalent of 38-380 (19-190mm in FourThirds). My newer C-750 was 6.3-63mm, but it too has an equivalent of 38-380mm. See why it's important to use 135/35mm format when comparing cameras?
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Old Sep 21, 2010, 8:17 AM   #6
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This dSLR stuff's a bit head scratching but fun!

The bridge camera I have is a Fuji S8100fd and I also have a Lumix TZ4.
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Old Sep 21, 2010, 8:52 AM   #7
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The Fuji has a 27-486mm equivalent (that's 13.5-243mm in FourThirds).

The Lumix has a 28-280mm equivalent (or 14-140 in FourThirds).

Later on if you want more reach you might opt to get a 2x teleconverter which multiplies your focal lengths by 2 times (40-150mm becomes an 80-300mm when using the teleconverter, which would have an equivalent of 160-600mm). Another option is the 70-300mm (equivalent of 140-600mm).

BTW, a site you should check out to learn more about your camera:
http://www.wrotniak.net/photo/43/index.html
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Old Sep 21, 2010, 9:03 AM   #8
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Quote:
Originally Posted by Mikefellh View Post
The Fuji has a 27-486mm equivalent.

The Lumix has a 28-280mm equivalent.
So, Sam, if you have the 14-42mm kit lens and get the 40-150mm lens, you have the 35mm equivalent of 28-300mm. Basically you'll have almost the same range of view as you had with the Lumix, but a lot less telephoto than you had with the Fuji (which is why Mike is mentioning the teleconverter). But your 4/3 image sensor is larger so you'll be (theoretically, at least ) getting better images.

Ted
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Old Sep 21, 2010, 9:07 AM   #9
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So, Sam, if you have the 14-42mm kit lens and get the 40-150mm lens, you have the 35mm equivalent of 28-300mm. Basically you'll have almost the same range of view as you had with the Lumix, but a lot less telephoto than you had with the Fuji (which is why Mike is mentioning the teleconverter). But your 4/3 image sensor is larger so you'll be (theoretically, at least ) getting better images.

Ted
Yep, that was my thinking. I have just looked at the teleconverters and they are way out of my price range. So it'll just be the lens, but that should cover all my bases, this camera is for better shots so for happy snapping I can use the Fuji.

Thanks for the help x
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Old Sep 21, 2010, 10:42 AM   #10
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Wow! I'm totally confused now.... I don't do math..

Simple answer without using algebra and calculus, is your 40-150 (Handy lens by the way, with some good bargains out there) doubles to 80-300mm on the old 35mm system.

Or to answer. 1.6X to 6X on your point and shoot ref. close as I need to know....

Looking forward to some shots soon.
Ken
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Last edited by Scouse; Sep 21, 2010 at 10:45 AM.
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