Nikon Coolpix 990 vs Coolpix 4500                             Comparison Shots
These Images Link to 1600X1200 shots, all images saved at same jpeg ratio in Photoshop.
                  Slight variance in exposure between the shots, but not a great impact.
         These comparisons are more about real-world photography than a scientific test.
All in-camera image adjustments switched to off (sharpening, contrast et al), with no Photoshop adjustments other than resizing
Pete the Penguin is 12 inches tall and was about 20 yards away.
Spot the Hot pixel?
Coolpix 4500, Swarovski AT80HD @ 20x
Coolpix 990, Swarovski AT80HD @ 20x
I tried to get both subjects to the same size in the final image, the cp4500 zoomed back more than the cp990. Overall there is little difference in the two images as far as definition and focus, the makers name on the Penguin is easily read in the cp4500 shot, and the holes for the speaker better defined (as are some other lines).
Noise is obvioulsy less in the cp4500, in turn reducing file size.
Reds are better on the cp4500, yellows better on the cp990....but this comparison is more about clarity of image and resolving detail.
Zooming in with the cameras there still isn't much difference in the two...possibly less than the first two. Make your own minds up.
Coolpix 4500, Swarovski AT80HD @ 20x
Coolpix 990, Swarovski AT80HD @ 20x
This Compactflash card was situated 18 yards from the camera, these link to 800x600 crops from the full image. Again, no in-camera image adjustments were switched on and no Photoshop adjustments
These shots were very interesting, the difference between the cp4500 and cp990 is very obvious. At first I assumed my cp990 shots weren't as good as they could be and spent two days trying to get the best possible shot....this is the best.
No need for comments.
My theory is that the extra resolution from the scope at 30x (more detail than 20x) is being used by the 4mp camera, where-as the 3mp cannot resolve more. I don't know for sure, I'm probably wrong and look forward to answers from those who do know.
Coolpix 4500, Swarovski AT80HD @ 30x
Coolpix 990, Swarovski AT80HD @ 30x
First Impressions
There are two things that immediately strike you as you handle the Nikon CP4500 for the first time, namely that it's smaller and lighter than previous Nikon 9** cameras. Despite it's lightness, the body is of 100% alloy construction as against the 50-50 of the CP995. Although it's appearance and build is better than the CP995, it's black finish makes it a runner-up to the CP990 in terms of  looks and to be honest it reminds me a bit of 'home-brew' electronics kits. Birders aren't particularly fashion conscious....so cosmetic appearances aren't number one on the shopping list.
The size reduction is a major boon to birders who are already laden down with a scope, tripod, binos and possibly voice recorder. The CP4500 should fit in most pockets, even with a scope adapter left on.
Having praised it's compact size, holding the camera in a conventional manner (hand around the grip) was uncomfortable as my fingers now hit the lens part of the camera...my hands aren't large.
Power is courtesy of the same Nikon Li-ion battery as the CP995, battery consumption semed fair but I'd be unhappy to go out for a day's birding with less than 3 of them. The Dual Force Pro battery pack works fine with the CP4500 and gives a generous supply of power for many hours of shooting.
In Use.
Start-up time seemed slow, I noticed the delay....something I had never done with my CP990.
The lens mechanism purred like a cat instead of the familiar grating noise reminiscent of a gearbox about to die. Seemed more rapid at finding a focus lock than I'd previously experienced with the 4x lens of the CP995 and definitely better at getting a focus lock in bad light than my CP990.
In continuous shooting mode I took five consecutive shots in about 4 seconds and the write time (Lexar 128mb 12x) was about 13 seconds....images were all about 1.38mb.
Although I can't measure the shutter-lag time....it didn't appear very good. Camera start-up time was also a bit slow, about 6 seconds when the zoom is set in 'last position'.. 
The New Layout

There has been a considerable amount of reworking of the button layout of the CP4500. A tiny joystick now controls many of the functions and the top lcd display has gone. The mode selector (a-rec, m-rec and playback on previous models) has also vanished and playback views are accessed by a new button on the rear panel. For much of the time a 'half-press' on the shutter release button will take you straight back to your shooting view.

The ISO/Flash mode button has moved to the lens section, a good idea as it's rarely used and gets it away from the main control area.

Another major change has been the downsizing of the LCD monitor, a worrying prospect for 'us' digiscopers who use the monitor to focus the scope.....thankfully the monitor seems far better in terms of resolution and general clarity, even viewable in quite strong light (bad weather has restricted experiments in sunshine). Unfortunately the current Extenda-view pro sunshades don't fit perfectly and block the buttons, a shame as the view through the 2x loupe of the Extend-view is very clear and not as pixellated as the previous monitors.
See further down for a very cheap alternative to the Extend-a-view that will fit on the CP4500. LATEST: New mini Extend-a-view fits cp4500.

The memory card compartment has changed again with the card slot being larger to accept Compactflash 2 and Microdrives. Strangely, you now have to put your card in with the label pointing away from you......it's going to take me a long time to get used to that! The card eject button has also changed to a rather quirky design, two pushes need to get the card out.

The ability to add audio notes to each image will be good for birders, adding notes on the bird...maybe you can leave the voice recorder at home for birding trips.

Image Quality
As for image quality with the CP4500, I'm starting to be extremely impressed with the results. Initially I was quite disturbed to see the images looking so soft in the camera's review mode. When opened up in Photoshop, the images still looked a bit soft. Fortunately the higher res images of the CP4500 withstand a large amount of unsharp-mask and the end results are now looking better than those from my cp990, capturing thin objects like pine needles far better.

The colours look far better out of the camera than my Nikon 990, though the images looked too contrasty at times with some burn-out, I suggest turning the contrast setting down to minimum.

The file sizes of the 'Fine' Jpegs looks small considering it's a 4mp camera, this is due to the fact that the images contain far less 'noise'.....switch to iso400 and see how big the files are.
Conclusion. (After 12months+)
My views on the cp4500 are still positive. The quality of image available from the camera is superior to the cp990 & cp995, the ability to resolve the finest detail is the most obvious benefit. The cp4500's speed of use for digiscoping (time from off to taking a shot) is a problem for many users, though just switching the monitor off and on is the best way for speed of use.
I have had the feeling that the percentage of 'keepers' is slighlty less than with the cp990, though I suspect that is a result of being greedy with the camera zoom and taking too many shots with the zoom at close to maximum, rather than closer to 3x (which I feel produces the better results.
A big bonus is the quality of the cp4500 at iso200, even reasonable quality prints can be made from the results at this setting (after some work in Photoshop)..... iso200 on the cp990 was pretty much useless for anything other than web images.
Without an external power supply for the cp4500, my views would have been less positive as far as convenience of use.... I do not rate the Li-ion batteries at all, rapid charging doesn't make up for their rapid exhaustion.
Nikon Coolpix CP4500 Review
From A Digiscoping Perspective, Including Comparison Shots Between CP990 & cp4500
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