Thứ tư, 16/2/2011, 08:58 (GMT+7) Canon vừa nộp bằng sáng chế cho ống kính 300mm F4 phiên bản mới thay cho mẫu cũ đã ra mắt năm 1997.  Chi tiết thông tin bằng sáng chế ống kính mới của Canon.
Hiện chưa có thông tin về giá bán và thời điểm ra mắt chính thức ống kính này của Canon. Hoài Anh Trở lại Số hóaTrở lại Số hóa Chia sẻ Lens tầm xa chất lượng cao cấp, thích hợp cho chụp động vật, thể thao ngoài trời, tích hợp chống rung. Giải pháp nối thêm khẩu telleconver 1.4X thành 420mm The EF 300mm f/4L IS USM Lens from Canon is a telephoto prime lens with two-mode optical image stabilization which compensates for camera shake up the equivalent of two shutter speed stops. Stabilizer Mode 1 corrects vibrations in all directions and is mainly effective for shooting still subjects and Stabilizer Mode 2 steadies the image when panning vertically or horizontally. An ultrasonic autofocus motor (USM) enables fast, smooth and silent autofocus and fulltime manual override allows for precise manual focus even in autofocus mode. Two ultra-low dispersion (UD) glass elements reduce aberrations and provide clear images and accurate color. The minimum focus distance for this lens is 4.9. The lens features a built-in lens hood and a removable, rotatable tripod collar for stable and secure tripod mounting, the lens is compatible with Canon 1.4x and 2.0x extenders. Compact L-series Telephoto lens with two-mode image stabilization. Mode 1 is best used on still subjects while mode two is designed for image stabilization while panning. I got mine at this link to it at Adorama; this link to it at Amazon is also a great place to get it. This all-content, junk-free website's biggest source of support is when you use those or any of when you get anything, regardless of the country in which you live. It helps me keep adding to this free website when you get anything through these links — but I receive nothing for my efforts if you take the chance of buying elsewhere. Never buy at retail, since Canon doesn't seal its boxes so you can't tell if it's a used or damaged lens. Thanks for your support! Ken. January 2015 Canon Lenses Canon Reviews All Reviews Canon 300mm Lenses Compared Why fixed lenses take better pictures Canon Extender EF 1.4x II Canon Extender EF 2x II Sample Images Palm, 19 December 2014. Canon 5D Mark III, Canon EF 300mm f/4 L, f/4 (wide open) at 1/800 at ISO 100, no lens profile used, Athentech Perfectly Clear v2.) Full resolution. Lamp, 19 December 2014. Canon 5D Mark III, Canon EF 300mm f/4 L, f/4 (wide open) at 1/1,000 at ISO 100, no lens profile used, Athentech Perfectly Clear v2.) Full resolution. Introduction This Canon 300mm f/4 is high performance, fast and lightweight telephoto lens for every Canon DSLR and 35mm EOS camera. It has great optics, fast autofocus and top-notch build quality. While most people prefer a 70-300 or 100-400mm zoom, other people prefer this fixed 300mm f/4 to Canon's 70-300 zooms for it's higher speed (better for action shots) and better optical quality. It's preferred over Canon's 100-400mm zooms for its lighter weight, lower price and higher speed. Just grab the focus ring at any time for instant manual-focus override. The tripod collar slides off the back, but leaves several metal nubbins poking out. This professional L lens is a bargain today because it's been in Canon's catalog so long. Canon has long since paid for its development cost, so it sells for much less than similar but newer lenses. The only gotcha is that this is one of Canon's first Image Stabilization lenses, and thus IS doesn't work to speeds as slow as do newer lenses. It's much lighter than 70-200/2.8 or 100-400mm zooms, and much sharper than a 70-200mm with a teleconverter. Specifications Canon EF 300mm f/4 L IS. enlarge. Name Canon calls this the CANON LENS IMAGE STABILIZER EF 300mm f/4 L IS. IMAGE STABILIZER and IS mean that you don't need a tripod. EF means "electronic focus;" there is an autofocus motor inside the lens. L means as expensive as L. Optics Canon EF 300mm f/4L IS internal diagram. UD Glass. 15 elements in 11 groups. Multicoated. Internal focussing. Focal Length 300mm. When used on an APS-C camera, it sees an angle of view similar to what a 485mm lens sees when used on an FX or 35mm camera. Angle of View, full frame 8.2º diagonal. 4.5º vertical. 6.8º horizontal. Diaphragm Canon 300mm f/4L IS at f/4. (EF diaphragm not visible). 8 straight blades. Stops down to f/32. Close Focus 4.9 feet (1.5m) from the image plane. Maximum Reproduction Ratio 1:4.2 (0.24x). Image Stabilizer Rated two stops improvement. Hard Infinity Focus Stop? No. Focus Scale Yes. Depth-of-Field Scale No. Infra-Red Focus Index No. Filters 77mm. Size Canon specifies 3.5" (90 mm) diameter by 8.7" (221 mm) long. Weight 45.770 oz. (1,297.5g), actual measured, with collar. 41.617 oz. (1,179.9g), lens alone without collar. 4.150 oz. (117.7g), collar alone. Canon specifies 42.0 oz. (1,190g). Hood Built-in telescoping hood. Hood locks in extended position with screw threads, bravo! Canon EF 300mm f/4 L IS with hood extended. enlarge. Caps New 77mm Canon pinch-type front cap and standard EOS rear cap. Tripod Collar The tripod collar comes off from the back. It's called the Tripod Mount Ring B (W). The 180/3.5 Macro uses the same ring, in black: Tripod Mount Ring B (B). Case Canon includes a very nice padded nylon LZ1128 case. This is a very useful sturdy padded case. You can use the double-handled zipper for solid closing, and once open, there's velcro on the top for shot-to-shot open and closing. Bravo! Introduced March 1997. Canon Model Number 2530A004. Included Lens. Tripod collar. Caps. LZ1128 case. Price, USA 2014 December: $1,350 after rebate. Box, Canon 300/4 IS. Performance Overall The Canon 300mm f/4 L is sharp and easy to use. Focus Auto/Manual Switching Just grab the ring anytime for instant manual-focus override. AF Speed AF is fast; not instantaneous, but fast. It's a little faster than the original 300mm f/2.8 L. AF Accuracy AF is always dead-on. Bokeh Bokeh, the quality of out-of-focus areas as opposed to the degree of defocus, is swell. Backgrounds get very soft and never distract. That's why 300mm lenses are a top pro choice for portrait lenses. Here's a full-frame sample. Click to enlarge: At f/4. enlarge. Coma I see no coma. It's sharp right out to the corners, even at f/4. Distortion There is no visible distortion. For more critical use, use these values in Photoshop's Lens Distortion tool to remove it: 100' (30m) -1.2 30' (10m) -0.5 10' (3m) -0.5 4.9' (1.5m) -0.7 © 2015 KenRockwell.com. All rights reserved. Ergonomics Canon EF 300mm f/4 L IS USM. It's great that the hood is built in, and locks so it's not always getting pushed back. The hood is tough plastic, with a tough rubber bumper on the front. The only weird thing is that the AF/MF switch is farther back than you'd expect, so you have to take the camera down from your eye in order to set MF or AF. Falloff (darkened corners) Falloff is invisible. It's negligible wide-open, and gone by f/5.6, even without a lens correction profile. I've greatly exaggerated this by presenting it against a gray background. In actual photography, it's invisible. Canon 300mm f/4 falloff on full-frame, no correction. © 2015 KenRockwell.com. All rights reserved. Filters, Use with There's no problem with vignetting, even using a stack of ordinary 77mm filters. Focus Breathing Focus breathing (the image changing size as focused) is mostly of interest to cinematographers who don't want the image changing size ("breathing") as the lens is focused among different subjects. The image from the 300/4 IS gets a little larger as focussed more closely. Lateral Color Fringes There is little to no green-magenta lateral color fringing without a lens profile. With a lens profile, there will be absolutely none. This is very good performance. Image Stabilization This has one of Canon's first implementations of Image Stabilization. It's much better than none at all, while the newest IS systems, like that in the 100-400mm II, work to much slower speeds. I usually get perfectly sharp shots at 1/60, and half the time at 1/30. With the 100-400 II, I get sharp shots most of the time at 1/15, about two stops better than with this lens. While newer IS systems are silent, this IS system makes a noise similar to a small motor or water running inside the lens. Macro Macro gets close. Here's what you get on full-frame at the close-focus distance: Longines 23ZS at close-focus distance at f/4. Crop from above at 100%. If this is about 6" (15cm) on your screen, printing the complete image at this same high magnification would result in a 40 x 60" (100 x 150 cm) print! This is super-sharp, and it's wide-open at f/4. Stop down and it ought to get even better. What look like chromatic problems are actually caused by the plastic watch crystal, and what looks like noise is the surface of the 60-year-old wristwatch. Mechanics Rear, Canon 300mm f/4 L IS, showing UC0321 date code. enlarge. The Canon 300mm f/4 L is built very well, mostly made of metal. Hood Tough plastic. Rubber bumper on front. Locks. Filter Threads Plastic. Forebarrel Metal. Focus Ring Rubber covered metal. Focus Cam Metal. Internals Mostly metal. Mid Barrel Metal. Tripod Collar Metal. Rear Barrel Metal. Identity Engraved metal plate. Mount Metal. Markings Painted. Serial Number Engraved into bottom rear of barrel and filed with black paint. Date Code Printed on rear light baffle as shown above. Mine has date code UC0321, meaning my sample was made in Canon's Utsunomiya plant in March 2014. Rear Gasket (moisture seal at mount) No. Noises When Shaken Very mild clunking. Quality Made in Japan. Sharpness Image sharpness depends more on you than your lens, and lens sharpness doesn't mean much to good photographers. It's the least skilled hobbyists who waste the most time blaming fuzzy pictures on their lenses, while real shooters know that few photos ever use all the sharpness of which their lenses are capable due to subject motion and the fact that real subjects are rarely perfectly flat. The Canon 300mm f/4 is very sharp, better than most Canon zooms. That's why people use it. If you can't get an ultrasharp image from this lens, you're doing something wrong. It could be haze or heat shimmer in warm weather, or subject or camera motion, or the simple fact that there is no depth of field at f/4 at 300mm. See also Fixing unsharp images. Here's Canon's MTF curve, which shows engineers just how nearly perfect it is: Canon EF 300mm f/4 L IS MTF Curve. Sunstars With its straight 8-bladed diaphragm, this Canon 300mm f/4 makes Canon-typical 8-pointed sunstars on brilliant points of light. Teleconverters Canon EF Extender 1.4x II Palm, 19 December 2014. Canon 5D Mark III, Canon EF 300mm f/4 L with Canon EF Extender 1.4x II at f/5.6 (wide open) at 1/640 hand-held at ISO 100, no lens profile used, Athentech Perfectly Clear v2.) Full resolution. It works well with the Canon EF Extender 1.4x II, making it a 420mm f/5.6. Autofocus is reasonably fast, and it's reasonably sharp. Without a lens profile, there are some magenta-green lateral color fringes. Load a lens profile and these will go away. Canon EF Extender 2x II The Canon EF Extender 2x II makes this a 600mm f/8. As an f/8 lens, only the center AF point works on my 5D Mk III and 7D Mk II. Autofocus works, but it will get stuck if you're too far out of focus. Help the lens by using the manual ring to get it close to being in focus, and AF will take you from there. It's reasonably sharp, but look out for heat shimmer problems if shooting at long distance outdoors. The lens will magnify the natural distortions in the air if there are temperature differences. Without a lens profile, there are magenta-green lateral color fringes. Load a lens profile and these will go away. Compared See Canon 300mm Lenses Compared. Versus 100-400mm zooms This 300/4 is significantly lighter than the 100-400mm zooms. It's also a stop faster than the 100-400mm zooms. The 100-400 II focuses a bit faster. While the 100-400 II has a much better IS system, this lens is a stop faster. For sports and action, this lens is better, while for dim-light no-tripod use, the new 100-400mm IS II is better — if you want to carry it. Versus 70-200mm zooms with converters This lens generally works better than fumbling with a 70-200/2.8 and a 1.4x converter. This lens works much better than a 70-200/4 and a converter, since it's much faster. Versus the original EF 300mm f/2.8 L The original 300mm f/2.8 L doesn't focus quite as fast, but they're about the same in actual use. The 2.8 weighs a ton by comparison. Optics are excellent in both of these. Since the f/2.8 is faster, the 2x extender works very well with it. Usage Canon 300/4L IS. Controls, Canon 300mm f/4 L IS. Stabilizer Mode Use MODE 1. MODE 2 is for panning. Stabilizer Leave it on, except on a tripod. Focus Range Limiter Use the 1.5m-∞ range. If your conditions are causing to the lens waste time "hunting" at close distances for focus, select the 3m-∞ range and you'll stop the lens from trying to focus closer than 3 meters (10 feet). AF — MF Use AF. In AF, it autofocuses, and you can grab the focus ring at any time for instant manual focus override. M is manual focus only and locks-out autofocus. Use this only if you don't want the AF system to try to focus. Recommendations This lens is for photographers who demand the highest optical quality, and are willing to forego the convenience of a zoom to get it. It also weighs much less than the 70-200/2.8 and 100-400mm zooms. Photographically, a 300/4 throws backgrounds much further out of focus than a 70-200 does at 200mm. This is why the 300/4 makes a great portrait and headshot lens. It lets us stand farther away for better facial rendering (perspective), and at f/4 blows-out any annoying background into a wall of soft color far better than any 200mm lens can at f/2.8. If money and weight are no object, I prefer the new 100-400mm IS II, but if you don't need a zoom and don't need great Image Stabilization — or if you prefer its faster aperture, lower cost or lighter weight — then get this 300/4 IS. More Information Canon USA's page on the 300mm f/4 IS. Canon Camera Museum's page. Help me help you I support my growing family through this website, as crazy as it might seem. 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