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PostPosted: Sun Sep 29, 2013 11:00 am 
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Hello,

I am a noob in field of DSLR(s) so want to get proper knowledge about its lenses. I had been using simple point and shoot up to now with 20x zoom.

As per I have learned, lenses of DSLR don't use "type"x zoom. They use focal length.
1. For Example: 18-200mm lens is roughly 11x zoom (dividing 200 by 18) and 50-500mm lens is 10x zoom (dividing 500 by 50). Since both lenses have nearly equal zoom, so what is the difference?
2. ABout the lens with 50-500 mm focal length, I've heard that it can easily capture images which are comparable to 50x zoom in point and shoot camera. So how does it works when the zooming is 500/50 = 10 X?

Please help me understand the logic that how can I know the true power of a lens in terms of zoom with given focal length in comparison to "type" x zooms of point and shoot.

OK for example

In a PNS camera, I have focal length range from 24mm-1200mm which translates it into a "50x" zoom.
and I have heard that "sigma 50-500mm" lens for a DSLR can easily click images with "50x" zoom if compared to a PNS (I understand that because of larger sensor in a DSLR, the image details will be more awesome, BUT I am trying to understand that how to relate zooming effect of a DSLR with a PNS).

Read somewhere that 50-500mm lens will zoom 2.5 times more than 18-200mm lens. So, does this mean that 24-1200mm lens on a PNS has better zooming capability then 50-500mm lens on a DSLR?

Please help me clear the confusion.


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PostPosted: Sun Sep 29, 2013 11:22 am 
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The zoom ratio is just a ratio, and the range it covers can vary. The focal length gives information about the field of view, but this also depends on the sensor size. Wide angle = short focal length.

To compare across systems, it is common to relate the focal length equivalent to 35mm film. If you have a DSLR with a "full frame" sensor (equivalent to 35mm film) then the focal length does not need adjusting for comparison. Most lower cost DSLRs have smaller sensors, which are proportionately smaller. This has the effect of showing you a smaller part of the image, equivalent to using a longer focal length on a bigger sensor. In short, for Canon multiply by 1.6x and for everyone else multiply by 1.5x.

The 50-500mm lens on a Canon would be equivalent to 80-800mm in that case.

You might say 800mm is still less than 1200mm of the 50x zoom camera, but here we have another factor. If the image quality is high enough, you can crop the image to show less of it. This is roughly comparable to "digital zoom". But with sufficient quality, you can get away with it more.

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PostPosted: Sun Sep 29, 2013 11:36 am 
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Another query..

As asked, 18-200mm lens has 11x zooming ratio and 50-500mm has 10x zooming ratio..

But 500 mm lens will zoom 2.5 times more than a 200 mm lens. Does this mean that zooming ratio of 50 - 500 mm lens is 10x multiply by 2.5 if we compare it to 18-200 mm lens?

Also is there any telephoto lens for Nikon 5200D which can give me similar/same viewing angle/zooming effect as a 24-1200mm lens of sony HX300 or Canon 50 hS can produce?

Edit: Just came to know "Focal Length 4.3 - 215 mm (35 mm Equivalent to 24 - 1200 mm)" for canon 50 HS.

So, which has better zooming view, a 50-500 mm lens on nikon D5200 or 4.3-215 mm lens on canon 50 HS


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PostPosted: Mon Sep 30, 2013 1:00 am 
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Hi srvkmr, welcome to the forum. I imagine the amount of zoom one needs depends on what you are going to shoot, zoom is not the end all of lenses. As stated above the sensor size of the camera determines the focal length of the lens I would ask, if you had the greatest zoom ever, what is the point if the IQ of the lens is hopeless.


Cheers

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PostPosted: Mon Sep 30, 2013 6:54 am 
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You shouldn't confuse zoom and reach. Zoom is a ratio, the ratio between the longest and shortest focal length. Reach is how close you can get. Both a 15-30mm lens and a 200-400mm lens have 2x zoom, but the 200-400mm lens has far better reach. An 800mm lens doesn't zoom at all, but has a massive reach

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PostPosted: Tue Oct 01, 2013 1:04 pm 
Amazing explanation, you've been a great help to me.


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PostPosted: Tue Oct 15, 2013 11:49 am 
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Some years ago I shot a comparison between different focal lengths on a crop frame camera (planning to redo something like that soon on both a full frame and a crop frame camera and more knowledge). I was standing on the same spot for all pictures:
http://simon.deobald.org/bilder/018mm.jpg (29mm equiv.)
http://simon.deobald.org/bilder/028mm.jpg (45mm equiv.)
http://simon.deobald.org/bilder/035mm.jpg (56mm equiv.)
http://simon.deobald.org/bilder/055mm.jpg (88mm equiv.)
http://simon.deobald.org/bilder/070mm.jpg (112mm equiv.)
http://simon.deobald.org/bilder/080mm.jpg (128mm equiv.)
http://simon.deobald.org/bilder/105mm.jpg (168mm equiv.)
http://simon.deobald.org/bilder/135mm.jpg (216mm equiv.)
http://simon.deobald.org/bilder/210mm.jpg (336mm equiv.)
http://simon.deobald.org/bilder/500mm.jpg (800mm equiv.)

Your Poweshot SX50 has slightly more wide angle and does reach a bit further than both of the ends shown here.

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PostPosted: Thu Oct 17, 2013 1:40 pm 
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I tried comparing zooming range of various DSLR lenses with different PNS camera lenses. My search boiled down to following:

1. Sony dsc Hx 1 : 20 x zoom, Focal length 5 - 100 mm (Focal Length Equivalent to 35mm Camera 28 - 560 mm).

2. Canon SX 500 IS: 30 x zoom, Focal length 4.3 - 129mm (35mm film equivalent: 24–720mm).

3. Nikon coolpix P520: 42 x zoom, Focal length 4.3-180mm (35mm film equivalent: 24–1000mm)

3. Sony Dsc Hx 300: 50 x zoom, Focal length 4.3 - 215mm (35mm film equivalent: 24–1200mm).

4. Canon 50HS : 50 x zoom, Focal length 4.3 - 215mm (35mm film equivalent: 24–1200mm).

5. Nikon D5200 with 18-105mm lens: Focal length 18-105mm (35mm film equivalent:

27–157.5mm)
6. Nikon D5200 with 18-200mm lens: Focal length 18-200mm (35mm film equivalent:

27–300mm)

If I compare zooming reach of Point no. 5 with Point no. 2 from above, then based of 35mm format, I can say that point no. 2 has reach 4.57 times that of point no. 5.

But, does it mean that in real life, zoom reach of point no. 5 is actually 4.57 times lesser than that of point no.2 (comparing original focal lengths of 4.3 - 129mm vs 18 - 105mm)?

Does this mean that lens in point 5 will not have longer reach as that of point no 2 or point no 4?
Actually, I have been using sony dsc hx - 1 up to now and I'm pretty much fascinated by nature photography (animals, birds, landscapes, flowers, sunsets). Wanted to upgrade to a DSLR (nikon D5200) but now I'm dubious that I will not get good zoom reach with DSLR in lower budget.
Any suggestion which set of lens can be used with D5200 to make its reach at least equivalent to point no 2. ?


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PostPosted: Thu Oct 17, 2013 2:06 pm 
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Yes, lens/body combo no. 5 will get "4.57 times less close" than no. 2. No. 5 will not get as close as No. 2 or No. 4. Comparing the actual focal lengths (a physical property of the lens) will only be meaningful for sensors of equal size. The equivalent focal length in 35mm format was created to make comparison across sensor sizes possible.

To get the reach of the Canon SX 500 IS (720mm eq. at the tele end), you need to mount a 480mm lens on a Nikon D55200 (720mm/crop factor 1.5 = 480mm). This leaves you with few cheap alternatives. The ones I can think of are: Sigma 50-500mm, Sigma 150-500mm and Tamron 200-500mm. These give you 750mm eq. focal length at the tele end

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PostPosted: Thu Oct 17, 2013 4:46 pm 
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janern wrote:
Yes, lens/body combo no. 5 will get "4.57 times less close" than no. 2. No. 5 will not get as close as No. 2 or No. 4. Comparing the actual focal lengths (a physical property of the lens) will only be meaningful for sensors of equal size. The equivalent focal length in 35mm format was created to make comparison across sensor sizes possible.

To get the reach of the Canon SX 500 IS (720mm eq. at the tele end), you need to mount a 480mm lens on a Nikon D55200 (720mm/crop factor 1.5 = 480mm). This leaves you with few cheap alternatives. The ones I can think of are: Sigma 50-500mm, Sigma 150-500mm and Tamron 200-500mm. These give you 750mm eq. focal length at the tele end


Thank you sir for suggesting the options. Ummm to be honest, I've never used a dslr before. I have used a PNS up to now with equivalent focal length of 28 - 560 mm and have captured photos like these (links below)

https://fbcdn-sphotos-h-a.akamaihd.net/ ... 8689_n.jpg

https://fbcdn-sphotos-g-a.akamaihd.net/ ... 7749_n.jpg

https://fbcdn-sphotos-a-a.akamaihd.net/ ... 1209_n.jpg


So can anybody please help me understand that how using a dslr will help me improve image qualities for capturing such type of photos?


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PostPosted: Fri Oct 18, 2013 11:12 pm 
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In very basic terms (there are plenty of complications and exceptions), a DSLR has an image sensor that dwarfs that of your average P&S. However, compared to a P&S, DSLR sensors have far fewer pixels relative to their surface area i.e. a lower pixel density. While this might sound like a disadvantage with all the marketing suggesting more pixels = better, a lower pixel density can be beneficial. If you take a 12MP DSLR and a 12MP P&S, the DSLR will have larger pixels, potentially allowing for better light gathering than the P&S. Along with the lower pixel density comes a reduced likelihood of image noise from less electronic interference between pixels and not having to ramp up light sensitivity as much with DSLRs, particularly in low light environments.

With the dragonfly (forgive my entomology) and the flower, what you're seeing is the effect of having a shallow depth of field, which refers to the distance between the nearest and farthest objects that stay in focus. The chances are that a lens with a wide aperture, also known as a fast lens (because you can shoot at a faster shutter speed than a standard lens but allow the same amount of light in due to the wider aperture) was used to take both shots. As most P&S cameras have limited manual aperture control, which sets your depth of field, it can be tricky trying to achieve that effect with them.

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