(Review based on use of a Retail unit with firmware version A1.00, B1.00, L1.002)
Nikon D3100 with 18-55mm F3.5-5.6G VRIntroduction:
The Nikon D3100 is the newest entry level DSLR from Nikon, coming in as a replacement for the D3000, which was looking a little dated even upon release in 2009. Nikon has provided some major upgrades to the D3100 over the earlier entry level models; first of all in terms of a new 14.1 megapixel CMOS image sensor, which is in place of the 10 megapixel CCD sensor that had been used in Nikon's entry level cameras from the release of the D40X back in 2007. Another upgrade over previous models is the addition of liveview, Nikon's first entry level DSLR with this feature. With the addition of liveview, Nikon also introduced 1080p (Full HD) video recording capabilities. The D3100 is the first Nikon DSLR to have 1080p video recording. Another first for the D3100 is full time auto focus (AF-F) while recording video, which can be useful.
How is the D3100 compared to the T2i and K-r? Those are the kind of question that I will attempt to answer in this review. I'll start off by saying that I cannot directly compared the D3100 against the Pentax K-r, as I have no access to one. In the conclusion I will compare my thoughts and feelings about of the D3100 vs the EOS Rebel T2i/550D, which I tested earlier this year.
Build Quality, Controls and Ports:
The D3100 is very light weight, only 501g without the battery or a memory card, and is made of industrial strength plastics (polycarbonate) in order to achieve that. The body is also smaller than the D3000, and D60 before it, but not by much. Overall the body feels well constructed, although it different than earlier entry level models like the D40 and D60. My first reaction was that the plastic was of a lower quality than the D40 and D60, but after using the camera for a while I realized the reason they feel different is a change in surface texture. The grip on the camera has been improved over earlier entry level models, first of all, since it is deeper, secondly because the grip itself is covered in soft rubber, rather than a rubber like plastic one. The camera is a little small in my average sized male hands, at times my pinky finger almost feels like it wants to slip under the body, but that doesn't take anything away comfort in holding the camera.
The buttons on the back of the D3100 are laid out similar manner to that of the D3000 before it, short of two new buttons and a switch. On the back upper right side there is the command dial, which allows you to change the shutter speed, aperture or a combination of the two, depending on what shooting mode you are in. To the left of the command dial is the AE-L/AF-L button, which can be used to lock the exposure and or focus. This button can be used for both or either one of those functions. The AE-L/AF-L button can also act as an AF-ON button, which means pressing that button, rather than half pressing the shutter, will activate auto focus. The first new features are the addition of the liveview switch and movie recording button on the back beside the 3" LCD. I like this button, switch combination far more than the way Nikon had these functions mapped out on the D90 and D5000. To activate liveview you similar push the switch and the camera raises the mirror and enables the liveview mode. Once you are in liveview, you can start and stop recording a video by pressing the button in the middle of the liveview switch.
Under the liveview switch is the four way controller, which gives you the ability to choose the active auto focus point when in any focusing mode other than auto focusing area. When you use auto focusing area, the camera automatically picks one or several of the 11 focus points to determine what will be in focus. I'll have more to say about auto focus later in the review. The four way controller also allows you to navigate the menu system, and in playback mode, to scroll through all the pictures currently stored on the SD card in the camera. The OK button in the middle of the controller has two functions, first to access a a selected item in the menu system, and in shooting mode tapping this OK button returns focus point to the center focus point, if another point has been in use.
The D3100 also has a new small rubber thumb rest, where the D3000 and earlier models simply had a dip in the plastic to aid holding onto the body, another nice touch. Another addition is the speaker, located under the 4 way controller, so that you can listen to recorded audio during movie playback. To the left of the speaker is the trash button, which only functions in playback mode. When you have selected an image you want to delete press this button once, the camera will ask if you really want to delete the image, if you press the trash button again it will. If you don't want to delete the image press the playback button.
On the left side of the body are several important buttons, first the playback button. When you press the playback button you can look at the images you have taken with the camera. The second button is the Menu button, which gives you access to the main menu system of the camera. I have more to say about the menu system on the D3100, but that will come later. The next two buttons the ones with the "+" and "-" magnifying glass are used to zoom in and out of images while in playback mode. The "-" button has a "?" beside it, and when you are in the menu system pressing this button gives you a brief description of what the highlighted setting does. It is like having a manual built right into the camera, and just another reason for a beginner to choose the D3100.
The second new button is the "i" button on the D3100 is on the lower left side of the body. The info button allows you to access a number of settings, such as auto focus mode, ISO, white balance, active D-lighting and more without diving into the man menu system. The addition of a separate info button on the back of the camera makes it faster to change settings, but as a result all the buttons on that side of the body got a little bit smaller. When I first started to use the D3100 I though that this change could make pushing the right button with gloves on difficult, but that proved not to be the case. I didn't test the camera with ski gloves on mind you, so I don't know what that would be like.
On the top of the camera there are three buttons, first the shutter button with is surrounded by the on off switch. With default settings half pressing the shutter will activate auto focus, while fully depressing the shutter will take a picture. To the lower right of the shutter release you'll find the "+/-" or exposure compensation button. In shooting modes P, S, and A this will adjust the way the light meter in the camera behaves, forcing it to lengthen or shorten the metered exposure. In Manual mode pressing this button and turning the command dial adjust the aperture setting. To the left of the exposure compensation button you'll find the info button, this button turns the rear 3" LCD on and off at any time (except in liveview).
The model dial is the next feature on the top of the camera. There are the typical Auto, Auto with no flash (lighting blot crossed out), auto scene modes (portrait, landscape, Baby, Sports, Closeup and Night) along with the Guide Mode and creative shooting options, Program Auto, Shutter Priority, Aperture Priority and Manual (P,S,A and M). The mode dial is slightly taller than on the D3000.
The next big change on the D3100 over previous entry level modes is the addition of the drive mode switch, which is located beside the mode dial. This is a feature that I was extremely happy to see added, the addition of that switch is one of the reasons I decided to upgrade my backup body to the D3100 from a D40X. The drive mode switch allows you to quick change between single, continuous, self-timer and quiet shooting modes without diving in the menu. Having a drive mode switch is one of the reasons I love using the D300 as my primary body, so as you can imagine having such a switch on the D3100 is very nice to have.
The last item on the top of the camera is the flash hotshoe, which is compatible with all modern Nikon and some third party speedlights (flashes).
Nikon has actually removed one feature from the D3100 that all previous Nikon entry level models starting with the D50 have enjoyed, the ability to fire the shutter using the low cost wireless IR remote, ML-L3. Yup, there are no IR sensors on the camera, so the remote wont work with the D3100. You can use the wired MC-DC2 remote that also works with the D90, D5000 and D7000 though. The addition of the port for the MC-DC2 means that you can now use the Nikon GP-1 GPS unit (or equivalent third party units) with the D3100.
Nikon has added several ports to the left side of D3100, first, as mentioned, there is now a port for the MC-DC2 wireless remote and GP-1 GPS unit. Under that there is a standard mini-USB2 port which you can use to download photos to your computer. I recommend using an card reader, rather than downloading right from the camera. Beneath that there is mini-HDMI port for watching images and recorded HD video on a HD TV. If you want to use the HDMI port you'll have to buy a cable though, since there is no HDMI cable included with the camera. Under the HDMI port is a standard definition video ports, but again there are no video cables included with the camera.
On the grip side of the body you'll find the SD/SDHC/SDXC card slot. To open the door you simply slide the door towards the back of the camera and it will pop open. As noted you can use high capacity SDHC and SDXC cards, the latter of which are usually 64GBs, but will be larger in the future. Unless you plan on shooting video all day it seems very unlikely that you'll need a card that large, since an 8GB SDHC card holds over 400 RAW (NEF) files, or around 900 fine jpeg files. In fact I'd recommend using three or four 8GB or 16GB cards over using larger cards, simply because if a 32GB or 64GB card gets corrupted you could loose a lot of images or video. I used 8GB Class 10 SDHC cards in the D3100 for the duration of the testing period.
Finally we move onto the bottom of the camera body, where the battery bay and tripod socket are located. The battery bay has a small retaining clip inside, so you don't have to worry about the battery falling out when you open the door, although it does slide down making it easy to remove. The D3100 uses the new EN-EL14 battery (also used by the Coolpix P7000), which is rated for 550 shots with the D3100 (1.7V, 1030mAh, 7.7Wh). Don't expect to get that many shots on a charge until the battery has been cycled (charged and discharged) 5-10 times, because it is only after 5-10 charges that lithium ion batteries reach their peak operating condition. The camera comes with the new MH-24 charger, which has an integrated plug, which means you no longer have to drag the power cord around with you, which is great for traveling.
In the tripod socket on the D3100 is centered with the lens mount, so the camera will work just fine for shooting panoramas. As noted on the bottom of the camera body, the D3100 is made in Thailand.
The optical viewfinder is an important part of any SLR camera, which is why I talk about the viewfinder in each camera I review. The D3100 may have a liveview function, which operates like the auto focus system on a point and shoot camera, but you'll get the best results, under most circumstances, by using the optical viewfinder. The D3100 has a pentamirror viewfinder (meaning it uses a series of mirrors rather than a full prism) with 0.8x magnification and 95% coverage. 95% frame coverage meaning 5% of what will be seen in the final image is not visible in the viewfinder. Having 95% coverage is common for entry level DSLR cameras, and is perfectly acceptable for most users. To get a Nikon DSLR with a 100% viewfinder you would have to buy a D7000, D300s, D3s or D3x. The viewfinder of the D3100 is the same size as the one found in the D3000 before it, and is slightly smaller than the one found in the D40, D40x and D60, although you wont be able to tell by looking, as the difference is insignificant. The viewfinder itself is clear and surprisingly bright for the size.
Along the bottom of the viewfinder there is a small LCD panel, where you'll see important shooting information such as, shutter speed, the lens aperture setting, the number of frames remaining, exposure and flash compensation, and flash readiness. In manual mode a meter will appear in this area as well. If you enable the rangefinder it tells you how close you are to achieving focus, this is a great tool to use when manual focusing. The D3100 does not display the set ISO in the viewfinder by default, and there is no setting that will allow you to do so. Again this is common in entry level DSLRs.
Also displayed in the viewfinder are the 11 auto focus points, which unlike earlier models are not shown with large black boxes that flash red when active. Instead only a small dot within the auto focus area lights up. There are still light etchings on the focusing screen that show the focusing area. The advantage to this is that the viewfinder is less cluttered, and likely a little brighter. The disadvantage is that it can be a little harder to tell which focus point you are using, and in low light conditions it looks as if more than one focus point is active, although that is not the the case, unless you are using auto area focusing mode (more on this later).
Metering and Auto White Balance:
The meter performs very similar to the D3000, which isn't bad. The Matrix Metering mode tends to aim at exposing for shadow areas, which works well when you use Active D-Lighting, but not as well without it. As a result I tend to use center weighted metering with the D3100. Thankfully the way the D3100 exposes in Matrix Metering mode is very consistent, so if you continually find some parts of the image are too bright you can use exposure compensation to correct that. There are times when it seems as if the D3100 is overexposing the sky, and sometimes it does, but that is because the light meter is trying to not underexpose the other parts of the image. Considering the somewhat limited dynamic range of current digital cameras, that is important. In the menu you can choose from Matrix (Evaluative) Metering, Centered Weighted and Spot metering. Unlike some other DSLRs you cannot adjust the size of the spot metering area with the D3100.
Auto white balance performance is rather good indoors compared some some other DSLR cameras that I have used. In fact, I'd say that auto white balance on the D3100 is the best of all the Nikon DSLRs that I have used to date in that regard. That does not mean that auto white balance on the D3100 is perfect, there are still times that you want to use the manual white balance settings. Note that the D3100 does not have a kelvin white balance adjustment feature. The camera does let you store one white balance preset though, which somewhat mitigates the lack of the kelvin adjustment.
The D3100 uses the same 11 point auto focus system first introduced with the Nikon D200 in 2005. The system has seen refinements over the last five years, such as the addition of 3D colour tracking in 2008 with the release of the D90. The same system, with tracking, was also used in the D3000 and D5000. The big difference between the implementation of the auto focus system in the D3100 compared to those earlier cameras is what you see in the viewfinder. As noted in the viewfinder section the D3100 uses small spots in the viewfinder rather than boxes. This makes using the individual points a little tougher in dark areas than the earlier implementations of this focusing system. I often found myself activating auto focus just so I could figure out where the focusing area was against my subject.
I find performance of auto focus in the D3100 to be very similar to that of the Nikon D90, which is good overall. The center focus point is cross type, and thus is more accurate for some subjects and in low lighting conditions. All of the other focus points are horizontal, and work best in good light. That being said, I found that auto focus performance in low light was much better than with the auto focus system on the D40x for example. The D3100's auto focus system is superior to the one found in the Canon EOS Rebel T2i/550D, and there is no doubt of that in my mind. After a short time using the T2i I avoided using any focus points other than the center one whenever possible. Using non-central focus points on the D3100 on the other hand is fine under general lighting conditions.
There are several auto focus modes available on the D3100. AF-A (Auto-Servo AF), which means that the camera will decide whether the subject you are shooting is moving or not. If it is moving then it will automatically start continuously focusing, if not then it will only focus once. This mode is best used for general photography or when you don't know what you'll be shooting. AF-S (Single-Servo AF), when you have press the shutter the camera will focus once. By default the camera will beep when focus is achieved in this mode (the beep can be turned off in the menu). This mode is best used when shooting still subjects, like landscapes, architecture and in some cases for portraits. AF-C (Continuous-Servo AF), in this mode the camera will continue to auto focus as long as you half press the shutter release. This mode is best used when shooting sports, or any subject that is moving, such as wildlife, pets, cars, and people who are walking or running.
There are also a number of different ways to use the 11 auto focus points to best meet your needs. First you have Single Point AF: in this mode you pick which one of the 11 auto focus point that you want to use. In many situations this is the best auto focus mode to use, because the subject that you want to focus on is well defined and is still or easy to track when moving. Next is Dynamic Area AF: in this mode you can still select which one of the 11 auto focus points are selected, but if your subject moves and enters one of the other auto focus areas the camera will detect that and shift the focus as needed. Next is Auto Area AF: This is the default auto focus mode on the camera, it looks into the data base of several thousand images stored in the camera and tries to figure out what the subject is. Personally I avoid using this mode, because it often will not focus on what I want, and it can be a little slow if it cannot find something that matches the images in the data base.
If you are in AF-A or AF-C focusing modes you can also choose 3D (also known as 3D Colour Tracking). In 3D mode the camera will track a subject when you recompose your shot. Do not mistaken this mode as something for tracking fast, or erratically moving subjects. Here is an example of how 3D mode works best; I want to shoot a sign, but the light is low and I want to be sure that the camera will lock onto my intended subject. I focus with the center focus point, then move the camera to get a better composition. When I recompose the shot I make sure that the sign falls under one of the 11 AF points, and the camera should track the subject. To do this you need to keep the shutter released half press the entire time. 3D works okay, and seems to work well if used in the manner intended.
The Menu System:
The menu system that Nikon has implemented on the D3100 is very basic, which makes sense considering that this camera is aimed at first time DSLR users. The menu is broken down in five parts, Playback, Shooting, Setup, Retouching, and Recent Settings.
The Playback Menu gives you access to a few controls, such as the ability to delete multiple images at the same time, allowing you to choose the playback folder, image information that is displayed in playback, image review (whether the camera automatically shows the shot right after you take it), Rotate Tall (Does the camera display vertical images horizontally or vertically on the rear LCD), Slide Show, and Printing.
The Shooting Menu gives you access to controls such as Picture Controls (settings that affect in camera jpeg output and RAW files edited in Nikon's ViewNX and Capture NX2), Image Quality, Image Size (Disabled when RAW is selected), ISO settings, white balance, image quality, Active D-Lighting, Auto Distortion Control (should the camera automatically remove distortion from jpeg files?) Colour Space (Adobe RGB or sRGB), Noise Reduction (On or Off), AF-Area Mode, AF Assist (will the auto focus assist light come on or not), Metering, Movie settings and built in flash settings.
The Setup Menu allows you to set basic function of the camera, along with some more advanced ones. First is the control for formatting memory cards (do this whenever you use a new card, or one you haven't used in the camera before), LCD brightness (+3 to -3), Info Display Format (Classic or Graphic, the latter is the default), Auto Info Display (Will the shooting information display automatically whenever the shutter release is not half pressed), Clean Image Sensor, Mirror Lockup (For cleaning only, not during shooting), Video Mode, HDMI (control HDMI output settings), Flicker reduction (60Hz or 50Hz), Time Zone and Date, Language, Image Comment (Attach a comment to images that you take, such as your name or copyright information), Auto Image Rotate (Will vertical images be vertical when downloaded to your computer or not), Dust Off ref photo (an image used by the camera to remove dust spots from images), Auto off timers (how long do menus, playback and the light meter stay active after inactivity?), Self Timer Delay (2 or 10 seconds), Beep (On or Off, I recommend off as the Beep gets annoying very fast!), Rangefinder (Camera shows you how close you are to achieving focus when manually focusing. When you see "| |" in the viewfinder, correct focus has been achieved. This is a much nicer way to manual focus than with the green dot. Note that this only works with CPU lenses).
File Number Sequence (On or Off. Does the camera start from 0 ever time you put a new card in, or keep going to 9999 before starting again?), Buttons (Set the functions of the Fn, AE-L/AF-L buttons, and whether or not Auto Exposure Lock (AE-L) is active when the shutter is half pressed), Slot Empty Release Lock (Will the camera take photos if there is no memory card in the SD card slot? There is no internal memory, so unless the camera is a display unit in a store, set it to locked!), Date Imprint (Will the date be marked on each image you take. Options are Off, Date, Date and Time, Date counter), Storage Folder (Select the folder you want the camera to write images to, or select an existing one. The default folder is D3100), GPS (GPS Settings, such as does the meter turn off when the GP-1 is plugged in. If so the GPS will power down and have to reacquire the signal next time the meter becomes active. It will also display the current position if available) and finally the Firmware Version (A 1.00, B 1.00, L1.002 are the defaults).
Retouch Menu: This menu gives you access to settings you can apply to images after you have taken them. The options are, D-Lighting, Red-eye correction, Trim (crop), Monochrome, Filter effects, Color Balance, Small picture (make thumbnail sized images), Image overlay (Lets you combine or stack two images, can be used to create the same effect as multiple exposures), RAW Processing (Make RAW files into JPEGs in camera), Quick Retouch, Straighten, Distortion Control, Fisheye (create a fisheye effect on images you have taken), Color Outline (put a boarder around your image), Perspective control (introduce distortion), Miniature effect (a tilt-shift like effect), Edit Movie (Basic Movie editing tools, like trimming, change the end time or take a still image from the movie file).
Last, but not least, is the Recent Settings Menu. This menu will display the most recent settings that you have changed. Unlike higher end Nikon cameras the D3100 does not have a My Menu setting for fast access to commonly used settings.
Image Quality and Low Light Performance:
All the other aspects of a camera are secondary to the quality of images that you can capture with it. The D3100 does not disappoint in the image department, even at high ISO sensitivities the retention of detail is very well handled. Unlike a lot of professional reviewers I don't do what I would consider studio tests, although I do a quick noise test on a little test bed that I have created. Real world images tell the story of any camera, so I suggest looking at the D3100 image gallery.
High ISO Noise Testing:
As for low light noise performance, there is a big improvement over the 10MP entry level models, like the D3000. From ISO100-800 images are basically noise free under most circumstances. ISO1600 is very usable, and with noise reduction any of the native ISO settings up to 3200 are fine. The high settings show noticeable colour noise, especially ISO 12800. That being said, I'd rather be able to shoot at those ISO sensitivities than not, because earlier entry level models maxed out at ISO3200 as a high setting. Like some other Nikon DSLRs I noticed that under some conditions noise can be a problem at low ISO sensitivities (ISO 400-800), but generally speaking that is not the case. I found that noise showed up at those lower sensitivities when shooting a dark subject against a bright sky, but using exposure compensation to properly expose the subject could have easily fixed that problem.
The Canon Rebel T2i shows slightly better performance at extremely high ISOs (over ISO3200), but only by about 0.3ev at the most. I found that the D3100 retains more detail at high ISO than the T2i, so I'd rather have that detail to work with in post processing than not. Do note that the T2i appears to have less luminance noise at ISO12800. The following images were all shot from a tripod in natural light, from a tripod. Many noise tests show 100% crops of an image, and while that does tell you something, I find that seeing the effect on all of the image is more important. Click on the images for a larger version to see noise in the shadow and highlight areas. Noise on the D3100 is very fine, and performs well for black and white images even at ISO12800.
Noise is non-existent for all intensive purposes
Still no visible noise
Still clean, but hints of noise start to appear if you under expose
Noise shows up in deep shadows or underexposed areas
Noise is now becoming apparent in dark areas and some in colours.
There is still no apparent loss of detail
Noise noticeable in shadows and somewhat in highlights.
Slight detail loss can be noticed at 100% view
ISO 6400 (Hi 1)
Noise is visible across the entire frame. Some luminance noise is visible.
Some detail loss, but not a lot considering the ISO sensitivity.
ISO 12800 (Hi 2)
Luminance noise very noticeable. Detail loss in dark areas is unacceptable.
Liveview and Video:
Nikon has introduced Liveview and Video to their entry level cameras for the first time with the D3100, so that means that these functions of the camera cannot be ignored in any review. As I noted under the first section of the review dealing with the controls used to access liveview, the new D3100 and D7000 have a much better way of doing so than older models like the D90, D5000. To start recording video on the D3100 you just press the red button in the middle of the Liveview switch, and tap it again to stop.
Video Files are recorded in several sizes, Full HD (1920x1080) at 24FPS, HD (1280X720) at 24, 25 or 30FPS, and Standard Definition (640x420) at 24FPS. Unlike the Canon T2i, which allows multiple frame rates at each setting, including 60fps, the D3100 is very limited in terms of control over how video is recorded. ISO control is locked in auto mode, and so is exposure control. Pressing the AE-L/AF-L button will lock the set exposure to prevent light levels from change while recording, unless the AE-L/AF-L button is set to AF-ON. The quality of the video itself is very good, although the jello effect that is seen on earlier DSLRs is also present on the D3100. This has more to do with the technology behind CMOS imaging sensors than the fault of Nikon, although I believe more can be done to reduce this effect than has been done in the D3100. The quality of the video files themselves are good, and just as for still images the camera performs well in low light.
Auto Focus in liveview and video mode; the D3100 is the first Nikon DSLR to allow continuous auto focus while recording video, which is a big step up from earlier cameras like the D90 and D5000, which could not auto focus while recording at all. First of all I'd like to say that the speed of auto focusing while in liveview is much faster than previous models, such as the D90, D5000 and D300s, although still not as fast as high end compact cameras.
There are three focusing modes in Liveview/Video Mode AF-S (Camera Focuses once), AF-F (Full Time Auto Focus) and Manual. Full time auto focus (AF-F) works well for slow moving subject that have a lot of contrast for the auto focus system to lock onto. For example, one of the sample videos on my website shows the camera tracking a jet coming in for a landing, and the camera was able to maintain focus 98% of the time. Focusing on fast moving objects or subjects with low contrast on the other hand leads to focus hunting or the system giving up altogether. Keep in mind that if you use auto focus while recording video, you will hear the focusing motor in the final video. Since the D3100 does not have an external microphone port this may bother some people.
Auto focus while recording is not up to the standard of a camcorder, but is a big step up from having no auto focus while recording at all. The implementation of auto focus on the D3100 and D7000 while recording video is about as good as it gets for DSLRs at the time this review was written. Sony's A33 and A55 are said to have better auto focus while recording video thanks to their translucent mirrors which allows the superior phase change auto focus system to keep working in liveview. I cannot confirm that since I have not tested either camera against the D3100.
Comments and Conclusion:
The Nikon D3100 is a small, and comfortable entry level DSLR that is targeted at first time users who are upgrading from point and shoot cameras. The features and controls of the camera make using it very easy for such users, especially with the Guide mode. I didn't cover the guide mode, simply because it is very easy to grasp, which is the idea behind it. I have been unable to find any major faults with the D3100, other than some slight back focusing on close subjects, which can be easily adjusted if I wanted the issue corrected.
I have enjoyed using the Nikon D3100, far more so than I did the Canon EOS Rebel T2i/550D. Part of that comes down to the fact that I am more used to Nikon DSLRs and also because I found the camera more intuitive overall. The T2i/550D does have more external controls, which is nice for quickly changing settings, but will also be far more intimidating for first time DSLR users as a result. The T2i/550D also has a higher resolution rear LCD, but the size is about the same. Honestly speaking, I haven't found the lower resolution of the D3100's 3" LCD to be a big issue. The D3100's 11 point AF system is totally superior to that of the 9 point AF system in the T2i/550D. I wouldn't use any focus point on the latter other than the center one, while I felt free to use each of 11 AF points on the D3100 in all but the lowest lighting conditions. Overall the speed of the two cameras is the same in terms of image recording and other critical functions like from the time you turn the camera on till the time you can take the first photo. The T2i/550D also has a slight edge (maybe 0.3ev) in high ISO performance, although I got the impression that the D3100 holds more detail. The D3100 with 18-55mm VR kit lens is at least $100 less expensive than the T2i/550D with the 18-55mm IS kit, which is also a plus for those on a tighter budget.
I mostly used the D3100 with the provided 18-55mm F3.5-5.6G VR kit lens, because that is what most buyers will end up using with this camera. Frankly I'm very impressed with this combination, and would not hesitate to recommend this combo to first time DSLR users. Combine the 18-55mm VR and the 55-200mm VR or 55-300mm VR and you have a very flexible camera system. If you want to be able to get faster shutter speeds for taking pictures of friends and family in low light for indoors, consider the Nikon AF-S 35mm F1.8G, which works well with the D3100. If you enjoy macro photography also consider the Nikon AF-S 85mm F3.5G VR DX Micro lens.
The only things that I can see missing from the D3100 is support for the wireless ML-L3 remote and a port for using a superior external microphone. When those are the only stand out issues, that says a lot. The Nikon D3100 is a very well balanced camera, and I don't think it would be too much to say that it is the best entry level DSLR on the market right now.
Who is the Nikon D3100 for?
First time DSLR users who want a simple and easy to use camera with better than point and shoot image quality, including students who are looking for their first DSLR. Users of higher end DSLRs who want a small DSLR for travel.
Who is the Nikon D3100 not for?
Demanding amateurs who want a lot of external buttons and controls. Demanding videographers who want lots of control over video recording.
- 14 Megapixel CMOS senor produces sharp, high resolution images for large prints
- Small and low weight (great for traveling)
- Excellent ISO noise performances right up to ISO3200 (ISO6400 & 12800 fine for B&W)
- High Performance 11 point Auto Focus System (Much better than T2i's 9 point AF system)
- AF-F (Full Time Auto Focus) while recording video (not great, but better than not having it)
- Decent indoor auto white balance performance (better than T2i/550D, but not perfect)
- Matrix Metering is consistent
- Easy to understand Guide Mode for beginners
- GPS support (Nikon GP-1 or equivalent third party units)
- Sound of auto Focusing can be heard during video recording
- No external microphone port for recording sound while recording video
- AF-F struggles to maintain focus on fast moving or low contrast subjects
- No "My Menu" for accessing commonly used settings like higher end Nikon DSLRs
- Cannot use low cost ML-L3 wireless IR remote, although MC-DC2 wired remote can be used