The D300 is worth upgrading from a D80 for
590634
I upgraded from a D80 and definitely think the D300 is worth the upgrade.  It some aspects it's night and day.  The image quality in ideal situations might not be that different, but the HIGH ISO performance of the D300 is much better and the 6/FPS of the D300 make it entirely useful for action/sports/nature shots.  That is the main reason I upgraded, the D80's 3/FPS were not enough.

Then there is the far, far superior auto-focus system on the D300.  The D300 focuses my Nikkor AF ED 80-200mm F2.8D lens faster than the D80 did making me not feel the need to upgrade to an AF-S lens in that zoom range.

The build quality of the D300 is far superior to the D80 and the extra buttons and their placement make it a much more efficient camera to use, that is if you are constantly switching between AF-C and AF-S focus as well as single point and multi-point focus.  No annoying exposure dial to get accidentally moved while in your bag anymore either (sometimes on my D80 it would get accidentally moved from A-priority to M-priority and I wouldn't notice and my first few shots would just be white).

Then there is the fact that the D300 uses compact flash cards which are more reliable than SDHC cards and far, far easier to handle as they are large and don't have exposed contact points.

Then there is the other fact the D300's built-in flash can act as a commander to fire an off camera flash (like the SB-600/800/900) which is extremely useful and makes for infinite more flash opportunities right out of the box.

Also, if you find the D80's LCD screen when reviewing shots to have lag when moving around and zooming into the photo, that is all gone in the D300.  That was one thing that really annoyed me about the D80, that lag.  With the D300, the lag is almost imperceptible, not to mention you get a larger and better 3" screen for reviewing shots on.

Another D300 feature I like is "Active D-lighting."  I use this feature often when shooting subjects that are backlit or in shadow.
2749332
I'll spare everyone from all the technical mumbo jumbo but coming from 20D that I purchased eight years ago, it's a fresh breath of air moving to something more updated.  Sure, it's three years old already but there's a bigger appreciation beating the crap out of my first DSLR and finally upgrading the body.

Noise?  Everyone is talking about how noisy the 60D and 7D can be it's nothing compared to the 20D or older models.  I was astounded how clean it looked at ISO 800 and 1600 with very minimal grain.  Sure, there will be noise at high ISO but from 20D's mere 'okay' images at ISO 800 and horrible grain at ISO 1600, I can shoot up to ISO 3200 and still suppress majority of the noise during post processing.  I know it won't be like the 5D MKII/MKIII or the 6D.  But for the price, what a huge leap.  Our family took a trip to Boston Children's Museum days ago and I was able to shoot at average ISO 3200 indoors and performed very well.  If low ISO is desired that's where the Speedlite will come in handy.

60D is 0.2fps slower than the 20D but it seems to focus more accurately, the shutter is quieter and I've been leaving it in a high shutter speed mode to capture multiple shots for any given scene.  There are basically more usable images is all I can say.

It opened up quite a bit of possibility with this body alone; astrophotography is something I want to try (just purchased Manfrotto 294 aluminum tripod) without worrying about excess noise.  I also don't worry about needing my Speedlite for most shots and of course if I ever want to shoot video with it the function is there.

Let's not forget battery life.  I set the output to smallest RAW which I took about 300 photos at the museum.  I didn't even put a dent in the battery.  Normally with 20D it'll easily eat up a third of battery life.  While I didn't use the Live View function often (drains the battery faster) for a day's trip worth it was nice not having to worry about carrying a spare battery.  When I put the battery in the charger at home after 400 photos the charger light was still blinking at the 3-pulse 75% full!

One thing I noticed coming from 1.8" screen to this giant 3.0" screen is that I can clearly see the picture detail and appreciate the photos at the same time.  Photography is becoming fun again.  This is what I needed after all these years.

7/16/2013 Update with some astrophotography:

Though I'm new to astrophotography, I've stacked some images shooting at ISO 1600, less than 25 sec shutter (the Rule of 600) along with my Tamron wide angle shot wide open (f2.8) and wow...what a difference.  Because of 60D's articulating screen, I can magnify to the brightest star using the x10 zoom function, set the lens on manual and focus (it doesn't focus at infinity but about one notch below).  Now I know there's 60Da specific for astrophotography (like the 20Da) but there's so much you can capture with this camera.  Luckily I live in a rural area and 30 minute drive away from most towns give me plenty of dark sky with stars so venturing out again once the new moon is out next month.

Now off to shoot some sunrise this week :)
1019012
I used to be a Nikon user and thought that it is by far better than anything Canon made but 2 months ago I switched to the 7D from a D300s and was very amazed at how good the camera is, I use it with a mediocre lens the 28-135 mm and it performs great. I shoot 3200 to 6400 ISO and the pictures are still acceptable and in my opinion better than the D300s. The best part over the Nikon are the ergonomics which are much nicer, with Nikon I had to use my right hand a lot while looking through the viewfinder which was a bit awkward at times but with 7D everything could be done just using the left hand.  I could only recommend this camera to anyone confused about buying one of the 2 cameras.
816509
I purchased a used D300 several months ago and while I have always been a Nikon shooter I'm still learning about some of the new features of the camera. The card is a great reference when I'm shooting an forget now to set the camera, since it's very different from my old D70.
453728
I loved my Nikon D50! and had no complaints.  But Santa gave me a D80, and who wouldn't want a few more MegaPixels, another half frame per second, and the ability to add a cool vertical grip :)  Now I love my D80, and have zero complaints :)
4276555
This Nikon replaces a Nikon CoolPix S9300 that was damaged when a tornado destroyed my house. I had really enjoyed the previous Nikon, and I like this one even more. The rotatable monitor which saves the screen from scratches and makes taking shots from unusual angles, including selfies, really easy. The addition of shooting modes that allow one to exert more control over photo taking is especially appreciated. In addition to fully automatic, there are program, shutter priority, aperture priority, and fully manual modes. Additionally you can edit the images on the camera, and you can take raw images. The new features make this camera very much like my Canon SureShot SX50 HS (50x optical zoom), which was also trashed in the tornado, and it still fits in a pocket (although a bit more snugly). Images are very sharp. The 30x optical zoom is quite amazing. If you're not at least an amateur photographer, you need to spend some time learning about the camera and using the appropriate modes in the appropriate situations. Automatic mode wants to produce a sharp photo on good light, so if you're taking photos in low light situations, you need to switch to an appropriate mode or your photo will probably be blurry. I also like that you can use it pretty much one handed.
3117925
This is my 5th digital camera in approximately the last 4 years. The Dimage 7i a serious upgrade compared to the Nikon 990(3.34 megapixel) I was using. The Nikon is a nice camera, but the Minolta 7i has more functions and greater resolution.
Battery life was my primary concern prior to purchasing the Dimage 7i. That turned out not to be an issue using good NiMH rechargable batteries (1600mAh or above). I was able to get over 70 photos on one set of batteries. I would recommend using the electronic view finder vs the LCD monitor to conserve battery life.
Because the camera is 5 megapixel, have several memory cards at least 128MB, preferably 256MB or above. They fill up fast when using at the higher resolutions.
Take a few minutes to read the manual to learn the tricks of the camera, it is well worth it.
1948177
I'm writing this in case any of you are in the same boat I was just a few weeks ago. I'm a budding photographer and have worked with a couple of Nikon D60 cameras. They served me well but as I progressed, I felt I needed a more professional camera. I didn't want to spend a boat load of money on a camera body since I had just spent some good cash on a 70-200mm F/2.8 lens. I looked at the new Nikons and although they are good, they are also still very very expensive (so that ruled out the D700/D800.)  The cameras I then started considering were used D7100 and a D300. My local camera shop had a used D300 body only camera on sale for under five hundred dollars and it came with a 1 year warranty from the camera shop. I asked for the shutter count and it was only 18400 so I jumped at that. I tried it out at the camera shop with one of their lenses and it looked and felt really good in my hands and every button seemed to be in the right place so you could make changes. I immediately noticed it was a professional camera. It is weather sealed so every port on it has a rubber cap. The shutter made a professional sound and didn't sound anything like the D40/D60 cameras. (I hear the D60 doesn't have a real shutter and it was more of a slider or something.)

I took it home and used my 50mm f/1.8 lens and snapped some photos to verify everything worked and the shutter count was what they said it was. The photos so far from this camera are outstanding. The focus is superb!! For those of you who don't know, the D300 has a 51point focusing system just like the high end Nikon cameras. If you're upgrading I would definitely recommend this camera even used. There are alot of really good deals on these used on Amazon, craigs, or ebay and the camera is totally professional; magnesium-alloy body and weather sealed! The shutter is rated to 150000 shots but many get well into 200k and even 300k. This really knocked up my photography up a few notches for sure!
3657813
I upgraded from the D7000 to the D7100 because I wanted more pixels, but if you use JPEG the camera tries to to get rid of noise with processing (even at ISO100) and give you really soft images, if you use RAW you get more pixels allright, but you also get a LOT MORE NOISE, SO FOR ME, UPGRADING FROM THE D7000 HAS BEEN A HUGE WASTE, paid a lot for the same I would have gotten with a d7000.

Then another problem, with ISO800 for instance, the D7000 did GREAT with Dynamic Range, but with the D7100 the dynamic range at ISO800 the Dynamic Range Drops to the same of a damn cellphone!!!

I just got much better images with the 14MP of the D7000 than with the 24 of the D7100, in everthing else it's practically the same camera.
4282676
I saved $40 by buying the upgrade.  I upgraded the trial version that came with my D700 and this version is even better than the previous version.
4029206
This is a great camera and overall big step in improvement when it came to revamping the body for more durability as an update to the 30d.  I also thought that the "Live View" was way overdue and wrote that as a major complaint for the 20d, and 30d.  I wonder why it was that cheap sub-$100 canons had live views whereas a $800-$900 camera (at that time) didn't.  It opens up so many more options to give the user the ability to have that when they want it, for example taking pictures at a concert when you have to lift the camera over your head.  But the one thing holding me back from not giving this camera full kudos is that it's still relying on a sensor that crops your image. The same image that's taken w/ a 35mm film camera and this one wouldn't be the same.  This also changes the focal length of lenses and you need to do some math to get the right focal length, other than that there are some lenses that compensate for the cropping factor of this camera.  The only digital slrs that have the full frame are the 5d and up.  Those cost a little more.  I think canon should think about converting most of its digital slrs to full frame, as the technology's out there, so why are they holding back?  If you're spending this much money on a DSLR, you should be getting your money's worth. Other than that, a very nice camera.
2867782
5D Mark iii is a fine camera, but I don't think that it is worth the upgrade if you already have 7d or 5d Mark ii or 1d Mark IV. I have two reasons:

1) Low light focus, you get full frame, better focus (even though the low light is not that great - I tried at ISO 25600, the focus went crazy. I can't get it focused at all). Comparing my old 5d mark ii, it is no better. It is only better when the light is good and the object being shot is moving then Mark iii performs better). My 1d Mark IV is actually quicker in focusing though at 16 meg pixel. True, the IOS quality has been raised from 6400 to 12800 low light wise between 1d mark iv and 5d mark iii. You still need a flash to have a good picture at ISO 12800 for 5d Mark III. The occasion of shooting at this low light is not that common, say maybe 10-20% of your overall shooting. I see improvement but not big enough to buy Mark iii instead of Mark II. Buying a used 1D Mark IV can be a better idea if you are talking about low light shooting and auto focus.

2) Cost - 7d is less than 2k, new 1d mark IV is 4.5K, Nikon d800 is 3k (with flash, better low light, faster focus). After looked at the features and the images taken, I am not sold on 5d Mark III. It is good but not good enough to be $500 than D800, $1.75k more than 7d. The full frame is fine but unless you develop pictures that big, 1.3x or 1.6x offered by 1d mark iv and 7d are enough for you if we talk about the picture quality only.

Pros - more focus points, 3.2 view finder, better video, better weather protection
Cons - not worth the 1k premium over 5d mark II or 1.75k over 7d, low light focus in need of improvement, not features competitive with Nikon d800

I returned mine and decide to keep my 1d mark iv and wait for the next upgrade opportunity.
3911846
Nikon has made some awfully good "Entry Level" Digital SLR cameras over the years.  The most recent were the D3100 and The D5100.  The main differences between the D3100 & D5100  was the D5100's articulating/brighter LCD and a bracketing feature.  The D5100 is about 10% heavier and costs a bit more than the D3100.  The D3200, the sucessor to the D3100, was released last year.  However the D3200 was arguably a step backward introducing a much higher resolution sensor (24MP) but at the undesirable cost of additional noise at higher ISO settings.

The D5200 uses a 24MP sensor like the D3200 (although the sensors seem to be from different sources; the D5200 uses a Toshiba sensor while the D3200 uses a Sony sensor).  This time fortunately, the high ISO performance has actually improved. The D5200 body is almost identical to the D5100 camera body including the articulating, high resolution LCD.  The LCD screen now highlights settings for ISO sensitivity, Aperture size (F Stop setting) & Shutter speed making these settings very visible even at a glance.  The LCD layout is much better (and different) than anything Nikon has previously used.  Nikon does not include an LCD on the top of this camera (or on any of their smaller DSLRs) presumably due to physical surface area constraints.

The key improvement is image quality. High ISO performance is actually improved despite the 50% increase in megapixels. ISO 1600 is almost indistinguishable from ISO 200.  ISO 3200 is very usable (but not really too far beyond that). Automatic White Balance for incandescent lighting, is still not great but has improved somewhat since the D5100 (but still not nearly as good as the older D5000); shooting raw is still really necessary to get the white balance right in artificial lighting (TIP: When shooting indoors, try "Sunny" instead of AWB). ISO settings can be incrementally increased between stops (ie ISO 2000) to help avoid using a higher than necessary ISO setting.

.JPGs are a little soft even after making in-camera adjustments; Shooting Raw and using Nikon's very good Image Editing software can enhance the photos quite a bit.  The built in flash is not great; an external speedlight with bounce capabilities is really essential for properly exposed photographs (or alternatively not using a flash at all and shooting at a higher ISO/slower shutter speed).  Like all modern DSLRs, 'live view' (LCD framing) can be used in lieu of the viewfinder.  However if you regularly prefer Live View to an optical viewfinder, probably the SONY offerings or even a compact system camera (ie the Olympus PEN series) is a better choice.

The auto focus system on this (and almost every other Nikon SLR) is really, really good.  Unlike the Canon SLRs (including some very expensive ones), the Nikon uses an independent infrared auto focus beam that focuses instantly on any fixed object under all lighting conditions (even total darkness).  Try shooting in total darkness with any other camera series (except the 4th generation Olympus Pen) and the camera will simply refuse to auto-focus.  The Nikon D5200 (and almost all Nikon SLR cameras) focuses under such conditions effortlessly.

This camera is expensive when compared to the current prices for the prior generation D5100 or D3100 which are both excellent cameras. Budget minded purchasers may want to give those cameras consideration or else wait for the inevitable price fall of the D5200.
1459959
I upgraded from a Nikon D300.

My Oh My, what an upgrade from DX to FX format, and 6 years in improved technology can achieve!

The D810 is still built like a tank, just like the D300, but with a lot more intuitive settings, easier and faster to apply and use.  I can spend time on composition, knowing that this high-tech camera will produce sharp, clear and well exposed images with an amazing dynamic range of colors.  The buttons are well organized and easy to use and the wide range of Menu features will likely satisfy the needs of many photographers.

One of the many stellar features of the D810 is its advanced Metering System.  For example, Matrix Metering takes into account the active focus point, and can be set to recognize faces, while determining optimum exposure for the scene.  Good metering, plus ultra fast and accurate autofocus and subject tracking has allowed me a little more time to choose proper aperture and/or shutter speed for the scene I envision.

Some reviewers have cautioned about blur (due to the high resolution?).  I get many beautiful blur free hand held shots.  I also try to be a little more cognizant of the shutter speed; I set a minimum shutter speed equal to twice that of the focal lens by setting the sensitivity parameters of the Auto ISO (Shooting Menu, ISO Sensitivity,Min Shutter Speed).  This is just one of the many features available to easily eliminate this issue.  I find that the high resolution and the much better dynamic range produces fantastic images with great detail for cropping.

I've been experimenting with the new Flat setting in Nikon's Picture Control (PC) system.  The Flat PC, released for cameras starting with the D810, is designed to prevent overblown highlights and clipped shadows while preserving an amazing amount of detail for post processing .NEF RAW files.  I shot the portrait of a child sitting on a brown leather recliner. I used a Portrait PC setting in the first shot and a Flat PC setting in the second. The histogram of the Portrait PC image showed obvious shadow clipping (loss of detail in the brown leather and the child's hair), vs. no clipping at all and a well distributed histogram in the Flat PC image, which was also in need of post processing.  Using Nikon's Capture NX-D software, I simply changed the Flat PC setting in the second image to Portrait; the image came back to life with a good dynamic range of colors and very fine detail in the brown leather and child's hair, while maintaining a histogram with NO clippings in the shadows area. This exact same processing can also be done in camera in the Retouch menu.  Nikon's PC system also allows you to perform additional adjustments to fine tune an image if you so desire.  I find their PC presets a good solution to quickly enhance images without having to "photosmith" in post processing.

I used the D810 DX format (Shooting Menu, Image Size). It still results in great pictures, approximately 20 MB less in .NEF file size but plenty of image resolution.  This camera provides the best of both FX and DX.

I was originally concerned about weight when combined with the Nikon 24-70mm f/2.8 G lens.  The only solution (which turned into an unexpected bonus) was to get into a daily special workout routine.

My gripes are as follows: I decided to use my 6 year-old camera strap from my D300, the one included with the D810 looks lighter and does not have as good a grip.  The USB cable clip (a plastic clip to prevent the USB cable from being disconnected from camera) is very difficult to insert and remove. The User's Guide book included with the camera is small with too small a print.

There are plenty of good learning resources online including the Nikon User's Guide (yes the guide is essential).  I am also using a couple of digital books one by Darrell Young and the other by Douglas Klostermann.

The D810 is allowing me to grow into a serious hobbyist photographer.
778333
Small, light and with great features and performance.  An upgrade to my D50.
2510888
I vastly prefer shooting with the battery grip. Increased stability with the D500 and 300mm f4 is key. And of course, the extra battery life in the field.
2639627
As a retired professional photographer who also has considerable experience with various digital cameras, I was somewhat reluctant to purchase a digital SLR that was meant to be used by 'First Time Digital SLR Users'. While it certainly can be easily used by novices in automatic mode, I soon realized that the camera has almost all the capabilities of higher-end Nikons, such as the D50, D70 and D80, but in a smaller and lighter version and even with some features the more expensive cameras are lacking.

Although light and relatively small, the D40 seems solidly built and the shape and controls are well thought out. The rear viewing screen is large and bright and the (through the lens) viewfinder is bright as well. When pressing the shutter button half way down you can clearly see when the subject is in focus. There is an extensive and well designed menu system

with which you can customize your camera and there is a "Help Button" that

brings up clear explanations as to what each menu item is for and what it does.

The camera takes excellent photos in all modes. What impresses me most is the lack of noise at high ISO settings. You get excellent results indoors without using flash at ISO 1600 and with very little noise. When using the pop-up flash, results are consistently good in macro and fill-in modes. Like all pop-up flashes, the range is limited and my next purchase will be a more powerful external flash. (Actually the range of the built-in flash is higher than most because of the high ISO usability.)

The kit lens is quite decent for most situations. A professional or serious photographer may want to invest in a more expensive lens, preferably one with 'Image Stabilization'. Unfortunately older Nikon lenses and even newer ones not designed for this camera cannot be used except possibly in complete manual mode, and that can be awkward at best. At under $600.- The Nikon D40 is a great value. While the camera sports only 6 megapixels, that is more than adequate for most photographers. Nikon just came out with the D40X camera that has 10 Megapixels which otherwise is almost identical to the D40. I personally wouldn't want to pay several hundred dollars more for it, however that is something you will have to decide.