Zoom lens

[Peatstack]

I'm confused about zoom lenses, I have a new d5100 with an 18-55 lens and a 70-300 lens but not impressed with the zoom capability. I have a small Nikon COOLPIX S9100 that seems a lot more capable of zooming in on shots than these bigger lenses. I have the opportunity to photograph eagles and other wild life from a distance and thought that upgrading from my point and shoot coolpix would get better results but I'm thinking Ive spent a lot of money(to me) for nothing. Any advice would be appreciated.

 

[480sparky]

The optical flaws that are inherent in a teeny P&S 18x zoom are disguised by it's teeny sensor. When you step up to a DSLR, the smallest flaw in an 18x zoom will readily shown in all it's glory. Towards that end, most DSLR zooms have a more limited zoom range to reduce the issues zoom have by nature.

That, and the P9100 has a 'digital zoom', which is basically cropping the images, tossing pixels overboard, and giving you an image that can't be enlarged without pixelization. "Digital Zoom" is a marketing ploy used to sell P&S cameras to the uneducated masses (no insult intended).

 

[Peatstack]

The optical flaws that are inherent in a teeny P&S 18x zoom are disguised by it's teeny sensor. When you step up to a DSLR, the smallest flaw in an 18x zoom will readily shown in all it's glory. Towards that end, most DSLR zooms have a more limited zoom range to reduce the issues zoom have by nature.

That, and the P9100 has a 'digital zoom', which is basically cropping the images, tossing pixels overboard, and giving you an image that can't be enlarged without pixelization. "Digital Zoom" is a marketing ploy used to sell P&S cameras to the uneducated masses (no insult intended).

Thanks Sparky,
Yeh I'm definitely one of the uneducated mass when it comes to the science of photography, at the moment anyway. I intend to progress. My thinking is bigger lens= closer shots. The more money you spend = closer shots Now I've learnt that aint so.
Onward Macbeth,

 

[CaptainNapalm]

I'm confused about zoom lenses, I have a new d5100 with an 18-55 lens and a 70-300 lens but not impressed with the zoom capability. I have a small Nikon COOLPIX S9100 that seems a lot more capable of zooming in on shots than these bigger lenses. I have the opportunity to photograph eagles and other wild life from a distance and thought that upgrading from my point and shoot coolpix would get better results but I'm thinking Ive spent a lot of money(to me) for nothing. Any advice would be appreciated.

Sparky gave you an excellent answer. Also, if you just take a photo shot at 300mm with your D5100 and crop it heavily around the bird, it should still produce a better quality image than the already zoomed in one your point and shoot camera takes with digital zoom. I've always turn the digital zoom feature off on all my point and shoot cameras as all it does is degrade image quality in camera.

Below is an example of a bird shot with x35 zoom on point and shoot camera vs. a bird shot with the 70-300mm lens at 300mm and then very heavily cropped on a Nikon D7000 (which produces the exact same images as your D5100 by the way). See the difference?

 

[KmH]

Here is some info that supports what has been mentioned so far:
Digital Camera Sensor Sizes: How it Influences Your Photography
Understanding Camera Lenses
Camera Lens Quality: MTF, Resolution & Contrast

 

[480sparky]

Thanks Sparky,
Yeh I'm definitely one of the uneducated mass when it comes to the science of photography, at the moment anyway. I intend to progress. My thinking is bigger lens= closer shots. The more money you spend = closer shots Now I've learnt that aint so.
Onward Macbeth,

The lesson here is Now to Spend More Money on "Good Glass".

 

[Peatstack]

Thanks Cap'n and Sparky,

I think I've got the hang of it now when in trim you press the zoom out to zoom in and Bobs yer uncle.