Nikon Coolpix P500

      Photo Review 8
      -/
      leadpic_P500_RD_front

      In summary

      A smart-looking digicam with a 36x zoom Nikkor lens, 12.1-megapixel, back-illuminated CMOS sensor and Full HD video recording. Nikon’s 12-megapixel Coolpix P500, which was announced in early February, is the higher-featured model of two that replace the Coolpix P100, which has been on sale for roughly a year. Featuring a back-illuminated CMOS sensor, it boasts a 36x zoom Nikkor lens, the longest so far in a Coolpix camera. It spans focal lengths from the equivalent of 22.5mm at the wide position to 810mm at full tele zoom. . . [more]

      Full review

      -
      leadpic_P500_RD_front

      Nikon’s 12-megapixel Coolpix P500, which was announced in early February, is the higher-featured model of two that replace the Coolpix P100, which has been on sale for roughly a year. Featuring a back-illuminated CMOS sensor, it boasts a 36x zoom Nikkor lens, the longest so far in a Coolpix camera. It spans focal lengths from the equivalent of 22.5mm at the wide position to 810mm at full tele zoom.

      Designed to appeal to amateur photographers who want an easy-to-carry camera that can cover most subjects and shooting situations, the Coolpix P500 is small enough to fit in the palm of your hand. It is offered in two colours: traditional black and a very smart deep red.

      Build and Ergonomics
      Like its predecessor (and many other extended-zoom digicams), the P500 is styled like a miniature DSLR and has a deep hand grip and prominent, protruding lens. The body design is largely unchanged since the P100, although the lens has a greater reach.

      The optical design of this lens contains 14 elements in nine groups and includes ED glass elements. Physically, it consists of two barrels: an outer barrel that is fixed in place and extends approximately 60 mm from the camera body and an inner, matte plastic barrel that extends a further 50 mm when the camera is powered up and zoomed out to the maximum tele extension.

      -
      P500_RD_front_l

      Front view of the Coolpix P500, red version. (Source: Nikon.)

      The grip is covered in finely-textured rubber and feels comfortable and secure in your hands. The shutter button with surrounding zoom lever is located at the front of the grip. A second zoom rocker, which provides more precise control, is located on the left side of the lens. You can re-assign this rocker to control manual focusing or snap the lens back to the wide setting with the Assign Side Zoom Control function in the set-up menu.

      Although the side zoom control requires you to use both hands, if you rely on the zoom lever around the shutter button, the P500’s body is well-balanced enough for shooting one-handed. Between the grip and the lens (and out of the way of your fingers) is a small LED lamp that doubles as a self-timer indicator and AF-Assist illuminator.

      -
      P500_RD_back_l

      Rear view of the Coolpix P500, red version. (Source: Nikon.)

      The rear panel is dominated by a 3-inch TFT LCD monitor with a relatively high resolution of 921,000 dots and a wide viewing angle. This screen has roughly double the resolution of the P100’s but provides similar adjustability. It can be tilted through 90 degrees upwards and 82 degrees downwards – but not in other directions.

      -
      P500_RD_LCD_positions

      Some of the positions in which the monitor can be set for shooting. (Source: Nikon.)

      Above the monitor sits an electronic viewfinder (EVF) that provides a colour display with a resolution of 230,000 dots. It covers 97% of the sensor’s field of view in capture mode and provides full frame coverage for playback. Dioptre adjustment is available via a knurled dial on its left hand side. Like all electronic screens, the viewfinder blacks out briefly when you take a shot but recovers rapidly.

      Left of the viewfinder is a button for switching between monitor and EVF, while to the right sits the Display button and a lever switch with a central button for controlling movie recordings. The lever sets the resolution while the button toggles recording on and off.

      A dial wheel sits close to the top right corner, with a moulded thumb rest that has a textured rubber surface just below it. The standard arrow pad, Play, Menu and Delete buttons lie further down to the right of the monitor screen.

      -
      P500_RD_top_on_l

      Top view of the Coolpix P500 with the lens in the wide position. (Source: Nikon.)

      The top panel has metal strap eyelets at each end but all controls are clustered on the right side of the camera. Behind the shutter button is a button for setting the drive modes and further back an on/off button. Both lie almost flush with the camera body.

      The mode dial is prominently located just right of the pop-up flash housing. It carries 11 settings: Auto, P, S, A and M plus a User mode for registering and accessing one suite of camera settings and pre-sets for Smart Portrait, Night landscape, Night Portrait and Backlighting subjects. A Scene mode, which accesses 16 additional pre-sets (including Scene Auto Selector) completes the array.

      The pop-up flash is raised by pressing a button on the left side of the flash housing and lowered by pushing it down. It has a range of about 0.5 to 8.0 metres when the lens is at the wide position or 2.2 to 4.5 metres at full tele extension. Paired stereo microphone grilles sit prominently between the flash and EVF housings.

      The memory card and battery share a single compartment in the base of the camera. The battery has to be charged via a USB cable (supplied). It plugs into a port beneath a rubber cover on the left side of the camera body. The HDMI port is also located here.

      A metal-lined tripod socket is located beside the battery/card compartment. Unfortunately, it’s well off the lens axis

      Features Comparison
      The P500 faces some tough competition in a sector of the market that’s becoming increasingly crowded. All the leading manufacturers have at least one model with a zoom range greater than 20x, as shown in the table below.

       

      Megapixels

      Zoom (35mm equiv.)

      PASM modes

      Raw

      Video

      RRP

      Nikon Coolpix P500

      12.1

      22.5-810mm

      Yes

      No

      1080p

      $599

      Canon SX30 IS

      14.1

      24-840mm

      Yes

      No

      720p

      $649

      Fujifilm HS10

      10

      24-720mm

      Yes

      Yes

      1080p

      $649

      Olympus SP-800 UZ

      14

      28-840mm

      No

      No

      720p

      $599

      Panasonic FZ100

      14.1

      25-600mm

      Yes

      Yes

      1080i

      $799

      Pentax X90

      12.1

      26-676mm

      Yes

      No

      720p

      $399

      Samsung WB5500

      13.8

      26-676mm

      Yes

      Yes

      720p

      $499

      Sony HX100V

      16.2

      27-810mm

      Yes

      No

      1080p

      $699

      At first glance, the P500 has a lot going for it: good wide-angle coverage, conservative resolution, plenty of user-adjustable shooting modes and Full HD video recording, all at a competitive price. However, the table above only points to one deficiency: lack of raw support.

      Other missing features include direct access to ISO and white balance settings and no support for auto rotation of images, both of which are found on most cameras with fewer features and lower price tags. No shortcuts are provided for adjusting metering patterns and the only focus shortcut (on the arrow pad) restricts you to four modes: auto, macro, infinity and manual. There’s also no hot-shoe for an add-on flash.

      Focus area selection, subject tracking, face detection, exposure bracketing, ISO and white balance and flash exposure compensation adjustments are all located in the menu and only available in the P, S,A and M shooting modes. The same is true for long exposure noise-reduction and Active D-Lighting settings. And there are two-and-a-half pages in the user manual listing functions that can’t be used simultaneously, in case you’re interested.

      On the plus side, you get comparatively sophisticated autofocusing and metering systems, the ability to restrict ISO settings, some interesting colour effects for RGB and monochrome images and a decent-sized stereo microphone for recording soundtracks with video clips. And point-and-press snappers should be satisfied with the camera’s performance in the full auto mode.

      A couple of new modes have been added to the Scene pre-sets. One is Nikon’s Scene Auto Selector, which automatically adjusts exposure settings based on six common scene types, defaulting to the Auto mode when it can’t find a match.

      Another is a Pet Portrait mode, which includes face detection. Two modes are provided for shooting panoramas. The Easy panorama mode records a sequence of shots as you pan the camera across the scene and combines them in the camera. The Panorama Assist mode provides an on-screen guide to help you line up successive shots in the sequence.

      The P500’s sensitivity range begins at ISO 160 and tops out at ISO 3200, where full image resolution is retained. Using the Fixed Range Auto function in the ISO sub-menu, photographers can limit the sensitivity span for the auto ISO mode to ISO 160-200 (the default setting) or ISO 160-400.

      In the full auto shooting mode, sensitivity is kept to ISO 160-800. The High ISO sensitivity auto mode enables the camera to extend this up to ISO 1600. Alternatively, users can choose individual settings from ISO 160, 200, 400, 800, 1600 or 3200.

      In addition to the Night Landscape mode and high-speed continuous shooting modes provided on the P100, the new camera includes a Night Portrait mode that records shots with and without flash and combines them to produce a well-balanced result. The Continuous H mode supports burst speeds up to eight, full-sized frames/second for five frames, while the Continuous L mode records at roughly 1.8 fps for 24 frames.

      There’s also a Pre-shooting Cache setting that starts to record images as soon as the shutter button is half-pressed. Resolution is reduced to two megapixels but the camera will store up to 25 frames at 15 fps, including five frames captured before the shutter button is pushed all the way down.

      In addition, the P500 provides two high-speed modes at reduced resolution. The 60 fps setting can record up to 25 shots at 2-megapixels, while the 120 fps mode records 50 frames at one megapixel resolution. Time-lapse recording is also provided with intervals of 30 seconds or one, five or 10 minutes.
      Sensor and Image Processing
      The sensor in the P500 is a similar backlit CMOS chip to the one used in the P100 but provides higher resolution (12-megapixels instead of ten). Linked to the sensor is Nikon’s new EXPEED C2 image processor, which underpins a variety of functions.

      As well as supporting HD video recording, VR image stabilisation and Active D-Lighting, the new processor includes algorithms for correcting several common aberrations and noise-reduction processing. It also supports the multi-shot modes common in cameras with backlit sensors.

      A new addition to these modes is a Night Portrait mode that records shots with and without flash and combines them to produce a well-balanced result. The Continuous H mode on the P500 supports burst speeds up to eight, full-sized frames/second for five frames, while the Continuous L mode records at roughly 1.8 fps for 24 frames.

      In addition, the P500 provides two high-speed modes at reduced resolution. The 60 fps setting can record up to 25 shots at 2-megapixels, while the 120 fps mode records 50 frames at one megapixel resolution. Time-lapse recording is also provided with intervals of 30 seconds or one, five or 10 minutes.
      Like its predecessor, the P500 is a JPEG-only camera, with 12 image sizes and three compression ratios selectable. Eight of the sizes are in 4:3 aspect ratio with two at 16:9 and one each at the 3:2 and 1:1 aspect settings. Typical file sizes are shown in the table below.

      Aspect ratio

      Image

      size

      Pixels

      File size

      Fine

      Normal

      Basic

      4:3

      12M

      4000 x 3000

      6.0MB

      2.9MB

      1.5MB

      8M

      3264 x 2448

      3.9MB

      2.0MB

      1.0MB

      5M

      2592 x 1944

      2.5MB

      1.3MB

      0.7MB

      3M

      2048 x 1536

      1.6MB

      0.8MB

      0.4MB

      2M

      1600 x 1200

      1.0MB

      0.5MB

      0.3MB

      1M

      1280 x 960

      0.6MB

      0.4MB

      0.2MB

      PC

      1024 x 768

      0.4MB

      0.2MB

      0.16MB

      TV

      640 x 480

      0.2MB

      0.14MB

      0.1MB

      3:2

      3:2

      3984 x 2656

      5.1MB

      2.6MB

      1.3MB

      16:9

      9M

      3968 x 2232

      4.25MB

      2.2MB

      1.1MB

      2M

      1920 x 1080

      1.0MB

      0.6MB

      0.3MB

      1:1

      1:1

      2992 x 2992

      4.4MB

      2.2MB

      1.1MB

      Movies
      Movie options are identical to the P100 and covered in full in our review of that camera. The default setting is HD 1080p and, as in the previous model, the angle of view of the lens is reduced for movie capture, compared with still picture shooting.

      Movie capture is triggered by a dedicated button on the rear panel. It’s surrounded by a ring switch with two settings: HD and HS. HD represents the standard movie recording settings, while HS allows the user to record in slow or fast motion.

      The entire optical zoom range can be used and still frames can be captured during recording at the same resolution as the movie frames. While recording normal movies, users can switch to HS Movie to capture decisive moments in sports, such as when a runner crosses the finish line. Slow-motion playback of HS recordings allow users to analyse motion.

      Playback and Software
      Nothing much has changed since the P100. The following options are supported in playback mode: quick retouch, D-Lighting, skin softening, filter effects, print order tagging, slide show, protect, rotate, copy and hide image, small picture resizing, voice memo and black border. Users can also select images as favourites and remove images from the favourites album, set sequence display options and choose a key picture to represent a sequence of shots.

      No software disk was provided with the review camera but we assume the disk contains Nikon’s View NX 2, which is available as a free download from Nikon Australia’s website.

      Performance
      Images straight from the review camera appeared slightly soft, even at ISO 160 (the lowest available) and noise-reduction processing at higher ISO settings made them even softer. Otherwise, performance was similar to the P100, higher resolution notwithstanding.

      Autofocusing in bright lighting remained fast when shooting stills, although it became erratic with moving subjects at longer focal lengths. It also flagged seriously in low light levels.

      The camera will continue shooting when the focus is slightly off so there’s a high incidence of unsharp photos in these situations. The image stabiliser was effective under low-light conditions but had problems coping with windy conditions when the camera was used at long focal lengths.

      Metering was generally good and exposure balance appeared to be slightly better than we found with the P100. Digital zoom shots were slightly soft and artefact-affected, although usable at modest output sizes.

      Imatest showed colour accuracy to be significantly better than we found with the P100 and saturation was more conservative. Skin hues were accurately recorded in most types of lighting and colour shifts, where identified, were relatively small.

      Resolution was slightly below expectations in our Imatest tests and well below expectations for most aperture settings at the shortest and longest focal lengths we were able to test. We obtained the best performance at 9.4mm with the aperture set at f/5.6, after which diffraction reduced resolution quite sharply. The graph below shows the results of our tests.

      -
      P500_Res-vs-FL-graph

      Edge softening was even more obvious than we found with the P100. As expected, it was most obvious at wide apertures. Our Imatest tests across the review camera’s sensitivity range produced similar results to the P100. Resolution remained relatively high up to (and including) ISO 1600 and only plunged for the ISO 3200 setting. The graph below shows the results of our tests.

      -
      P500_Res-vs-ISO-graph

      As with the P100, this performance was only borne out in actual shooting tests for flash exposures. Flash exposures were well balanced across the camera’s ISO range but shots taken at the highest ISO settings appeared a little soft.

      Long exposures showed visible image noise from ISO 400 on and we were unable to use exposures longer than two seconds in the S mode and four seconds in the M mode, which made it difficult to obtain correctly-exposed shots at higher ISO settings.

      Imatest showed lateral chromatic aberration to be similar to the P100 and moderate at almost all of the focal lengths and apertures we tested. However, few test shots contained coloured fringing, although a little was detected in close-ups in subdued lighting. In the graph below the red line marks the border between ‘negligible’ and ‘low’ CA, while the green line separates ‘low’ and ‘moderate’ CA.

      -
      P500_CA-graph

      Barrel distortion was evident at the wide-angle settings. However, it was largely resolved by the middle of the zoom range. Slight pincushion distortion could be seen at full tele zoom but it would not affect normal shooting. (Unlike the P100, the P500 doesn’t provide Distortion Correction.)

      The auto white balance delivered similar results to most digicams we’ve tested, failing to correct the orange cast from incandescent lighting but producing close-to-natural colours with fluorescent lights. The pre-sets tended towards slight over-correction, while manual measurement produced neutral colours.

      When used for fill-in lighting, the flash proved too powerful for subjects within a metre or two of the camera. However, reducing its exposure levels by 0.7 to 1.0EV delivered pleasing results. Examples are shown below.

      -
      P500_DSCN0306_flash

      The top image was taken with the flash at the default intensity, while for the lower image the flash exposure was reduced to -1.0EV.

      Video quality was poor, particularly with the HS settings. We also encountered many instances of the rolling shutter effect when shooting moving subjects. In addition, the AF system had problems keeping pace and clips were generally soft and artefact-affected.

      However, audio quality was better than average and you can use the zoom and autofocus while shooting clips without them being picked up by the microphone unless you’re recording in a very quiet place. Clips from high-speed movies, although low-resolution, appeared sharper and less artefact-affected than HD clips; VGA movies were somewhere in between.
      Our timing tests were conducted with an 8GB SanDisk Extreme III SDHC card. The review camera powered up ready for shooting in approximately 1.2 seconds and we measured an average capture lag of 0.3 seconds, which was reduced to less than 0.1 second when shots were pre-focused. Shot-to-shot times averaged 1.5 seconds without flash and 2.4 seconds with. High-resolution images took an average of 2.2 seconds to process.

      The full-resolution, high-speed burst mode captured five frames in just over half a second, which is in line with specifications. In the standard continuous shooting mode, the review camera was able to record ten 4000 x 3000-pixel shots in 6.8 seconds, which is somewhat slower than specifications. It took 6.3 seconds to process this burst.

      The High Speed Burst mode performed to specifications, recording 1280 x 960-pixel images at approximately 120 frames/second. It took 3.2 seconds to complete the processing of this burst.

      Buy this camera if:
      – You’d like an ultra-zoom camera with an adjustable LCD screen.
      – You want an ultra-zoom camera for time-lapse recording.
      – You want to shoot widescreen, Full HD video with stereo soundtracks.
      Don’t buy this camera if:
      – You want high image resolution across the camera’s adjustment range.
      – You want to shoot raw files (this camera is JPEG only).
      – You require high-quality images in dim lighting.
      -You want to shoot HD videos of fast-moving subjects in variable lighting conditions.

      IMATEST GRAPHS

      -
      P500_DSCN0141_colorerror
      -
      P500_DSCN0141_colors
      -
      P500_DSCN0141_YBL73_ca
      -
      P500_DSCN0141_YAR43_cpp
      -
      P500_DSCN0141_YBL73_cpp

      SAMPLE IMAGES

      -
      P500_DSCN0148_AWB-tung

      Auto white balance with incandescent lighting.

      -
      P500_DSCN0152_AWB-fluoro

      Auto white balance with fluorescent lighting.

      -
      P500_DSCN0001_wide

      4mm focal length, ISO 160, 1/400 second at f/5.6.

      -
      P500_DSCN0002_tele

      144mm focal length, ISO 160, 1/400 second at f/5.7.

      -
      P500_DSCN0003_digizoom

      Digital zoom shot; equivalent to 461mm focal length, ISO 160, 1/500 second at f/5.7.

      -
      P500_DSCN0017_close

      Close-up; 4mm focal length, ISO 400, 1/400 second at f/3.4.

      -
      P500_DSCN0017_fringing-crop

      Crop from 100% enlargement of the above image file, showing coloured fringing along well-defined edges.

      -
      P500_DSCN0162_night-ISO160

      Two-second exposure at ISO 400; 9.4mm focal length, f/4.

      -
      P500_DSCN0164_night-ISO800

      Two-second exposure at ISO 800; 9.4mm focal length, f/4.

      -
      P500_DSCN0167_night-ISO3200

      1/2 second exposure at ISO 3200; 9.4mm focal length, f/4.

      -
      P500_DSCN0156_flash-ISO160

      Flash exposure at ISO 160; 23mm focal length, 1/30 second at f/5.

      -
      P500_DSCN0158_flash-ISO800

      Flash exposure at ISO 800; 23mm focal length, 1/30 second at f/5.

      -
      P500_DSCN0160_flash-ISO3200

      Flash exposure at ISO 3200; 23mm focal length, 1/30 second at f/5.

      -
      P500_DSCN0010

      Stabilisation test; 144mm focal length, ISO 400, 1/50 second at f/5.7.

      -
      P500_DSCN0269

      Skin hues; 8mm focal length, ISO 400, 1/4 second at f/4.2.

      -
      P500_DSCN0261

      38mm focal length, ISO 160, 1/50 second at f/6.3.

      -
      P500_DSCN0199

      144mm focal length, ISO 160, 1/500 second at f/5.7.

      -
      P500_DSCN0224

      144mm focal length, ISO 200, 1/400 second at f/5.7.

      -
      P500_DSCN0252.MOV_1080p

      Still frame from 1080p HD video clip.

      -
      p500_DSCN0257.MOV_720p

      Still frame from 720p HD video clip.

      -
      P500_DSCN0258.MOV_VGA

      Still frame from VGA video clip.

      -
      P500_DSCN0250.MOV_HS320

      Still frame from high-speed video clip.

       

      Specifications

      -
      leadpic_P500_RD_front

      Image sensor: 6.16 x 4.32 mm BSI CMOS sensor with 12.75 million photosites (12.1 megapixels effective)
      Image processor: EXPEED C2 dual image processors
      Lens: Nikkor 4.0-144mm f/3.4-5.7 lens (22.5-810mm in 35mm format)
      Zoom ratio: 36x optical, up to 4x digital
      Image formats: Stills – JPEG; Movies – MOV (H.264/MPE4G-4 AVC, Audio: AAC stereo)
      Image Sizes: Stills – 4000 x 3000, 3264 x 2448, 2592 x 1944, 2048 x 1536, 1699 x 1299, 1280 x 960, 1024 x 768, 640 x 480, 3984 x 2656, 3968 x 2232, 1920 x 1080, 2992 x 2992; Movies – 1920 x 1080, 1280 x 720, 640 x 480
      Shutter speed range: 2-1/1500 seconds (Max. 8 seconds in A or M mode)
      Self-timer: 2 or 10 seconds delay
      Image Stabilisation: Image sensor shift + electronic vibration reduction (VR)
      Exposure Compensation: +/- 2EV in 1/3EV steps
      Focus system/range: Contrast-detect AF with 99 focus areas, face priority, auto (9-area selection), centre and manual AF point selection; range – 50 cm to infinity; macro to 10 cm
      Exposure metering/control: 256-segment matrix, centre-weighted, spot, spot AF area (with support for 99 focus areas)
      Shooting modes: Auto, P, S, A and M
      ISO range: Auto (ISO 160 to 800), ISO 160, 200, 400, 800, 1600, 3200
      White balance: Auto, Pre-set manual, Daylight, Incandescent, Fluorescent (x3), Cloudy, Flash
      Flash modes/range (ISO auto): TTL auto flash; range – 0.5 to 8.0 metres
      Sequence shooting: Max. 8 frames/second at 4000 x 3000 pixels or120 frames/second at 1280 x 960 pixels
      Storage Media: 102MB internal memory plus expansion slot for SD/SDHC/SDXC cards
      Viewfinder: Colour 0.6 cm EVF with approx 230,000 dots and dioptre adjustment
      LCD monitor: 3-inch TFT LCD with 921,000 dots; tiltable 82 ° downward, 90 ° upward
      Power supply: EN-EL5 rechargeable lithium-ion battery; CIPA rated for approx. 220 shots/charge
      Dimensions (wxhxd): Approx. 115.5 x 83.7 x 102.5 mm (excluding projections)
      Weight: Approx. 494 grams (including battery and card)

       

      Retailers

       

      CamBuy

       

      www.cambuy.com.au
      Digital cameras, lenses and accessories with 100% genuine Australian manufacturer’s warranties.
      Ph: (02) 9029 2219

      Camera House

       

      -
      CH_Logo120

      www.camerahouse.com.au
      Ph: 133 686
      The largest speciality photographic retail chain in Australia.

      Camera Pro

       

      www.camerapro.net.au
      CameraPro Pty Ltd
      Suite 607, 180 Queen St, Brisbane 4000
      Tel: 07 3333 2900
      Australian owned and run company based in Brisbane.

      Camerasdirect

       

      -
      CamerasDirect133

      www.camerasdirect.com.au
      Retailer of digital camera equipment and more.
      Secure online shopping and delivery across Australia.
      Ph: 1300 727 056

      Camerastore.com.au

      Camerastore.com.au
      Ph: 1800 155 067

      Camera-Warehouse

       

      -
      camera-warehouse120

      www.camera-warehouse.com.au
      Comprehensive range of digital cameras and accessories online (www.camera-warehouse.com.au) and an online print service (www.royalexpress.com.au).

      Digital Camera Warehouse

       

      www.digitalcamerawarehouse.com.au
      174 Canterbury Road 367 High Street
      Canterbury Northcote
      NSW 2193 VIC 3070
      Ph: 1300 365 220

      Electronics Warehouse

       

      www.electronicswarehouse.com.au
      1300 801 885
      Australian retailer of Vapex rechargeable batteries offering factory direct prices and fast, free shipping Australia wide.

      <

       

      Photographic Equipment & Supplies – Retail & Repairs. Click here for list of stores.

      Ted’s Cameras

       

      -
      Teds-Logo120

      www.teds.com.au

      1800 186 895
      Big range of cameras and photographic products with stores in most states and online.

      Rating

       

      RRP: $599

      Rating (out of 10):

      • Build: 8.5
      • Ease of use: 8.0
      • Autofocusing: 7.0
      • Still image quality: 8.0
      • Video quality: 7.0
      • OVERALL: 8.0

      Buy