Iris Lens
How To Make Proper Use of Lens Apertures
The diameters of all digital SLR camera lenses are controlled by a metal-bladed iris. The size of the iris can be regulated by the image taker using the standard aperture range, which begins at 1 – the biggest diameter – and gradually becomes smaller on a logarithmic scale that is based on the square root of two.
The idea is to make use of an aperture with a shutter speed that yields the right exposure. Luckily, with today’s digital SLR cameras all you have to do is to decide on the relevant aperture size and the camera’s electronics can decide on the right shutter speed to produce the appropriate exposure.
This will occur on a digital SLR camera that is set to aperture priority mode. If you aspire to become creative you can put your digital SLR camera in manual mode and simply select the required aperture and the shutter speed. But you have to be careful here by selecting the shutter speed first, and then decide on the aperture. If you do it the other way around, it might not work.
You have to understand that when choosing sizeable apertures you will generally obtain photographs that have a minimal depth-of-field. This means that the background, and at times the foreground of a subject, will not be in focus. This effect is superb for portraits and when you do not want any distraction in a scene.
If you require more of the photograph to be in focus you will have to go for a smaller aperture. Unfortunately, a smaller aperture will mean less light entering the lens and thus the shutter speed will be by design reduced to preserve a reasonable exposure.
A longer shutter speed means that there is greater risk of experiencing camera shake, which can lead to blurring. It is a delicate balancing act actually. You either reduce the depth-of-field to acquire the desirable exposure, or you experience blurring because there is insufficient light.
Nevertheless, there is a smart way to circumvent this drawback. In order to lessen the probability of image blurring, all you have to do is to put your camera on a bean bag or a tripod, then utilize a remote release cable or the camera’s self-timer to minimize unwanted camera movement, and that is all there is to it.
Lens apertures are actually ratios of the lens’s focal length and are given as f/numbers, like f/3.5, f/8, f/22, etc. These are also referred to as f/stops, or simply stops. The bigger the f/number, the smaller is the aperture. So an aperture of f/20 is considerably smaller than one of f/3.5.
About the Author
Chris Smith gives photography tips in his weekly ezine, which you can obtain for no cost. He has also put together a complementary report for you called How To Master White Balance, which can help you solve any white balance problems that you may encounter. To download it instantly and to obtain the ezine please visit: http://photography-expert.com
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1 Pcs 5-50mm Manual Zoom Auto-Iris Lens U2S $30.00 |
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12mm Auto Iris CCTV Lens For CS Camera True F1.2 U2S $14.00 |
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6mm Auto Iris CCTV Lens For CS Camera True F1.2 U2S $13.00 |
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8mm Auto Iris CCTV Lens For CS Camera True F1.2 U2S $11.50 |
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Any 4Pcs 4,6,8,12,16mm Manual IRIS CCTV Lens True F1.2 U2S $16.00 |
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F1.2 6mm Focal Length Fixed Iris Lens for CCTV Camera $7.93 |
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Adjustable 3.5~8mm Auto-Iris CCTV SECURITY CAMERA Vari-focal Lens, CS mount $25.00 |
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Adjustable 2.8~12mm Auto-Iris CCTV SECURITY CAMERA Vari-focal Lens, CS mount $39.95 |
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Super WDR 650TVL SONY CCD OSD Mini Camera W/ 2.8-12mm Auto Iris Lens $103.90 |
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1/3″ Image Format Black 4-9mm Manual IR Iris Lens $15.31 |
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12mm-30mm CS Lens Manually IRIS for Board Camera $23.99 |
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F7H-NEW CCTV AUTOMATIC IRIS 3.5-8mm CS-MOUNT LENS $23.87 |
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F7I-NEW CCTV AUTOMATIC IRIS 6-15mm CS-MOUNT LENS $26.86 |
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F7J-NEW CCTV MANUAL IRIS 5-100mm CS-MOUNT LENS $67.17 |
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F7K-NEW CCTV MANUAL IRIS 4-9mm BOARD MOUNT LENS $19.39 |
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F7L-NEW CCTV MANUAL IRIS 2.6-6mm BOARD MOUNT LENS $22.38 |
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F7M-NEW CCTV AUTOMATIC IRIS 5-100mm CS-MOUNT LENS $74.64 |
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FUJINON WIDE 2.7~13.5mm Auto-Iris CCTV SECURITY CAMERA Vari-focal Lens, CS mount $55.00 |
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TTH COOKE 8in (203mm) f4.5 “SPECIAL” Anastigmat Uncoated lens with Iris Diaph: $78.58 |
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1/3″ F1.4 CS Mount 2.8-12mm Auto-IRIS DC Varifocal Lens for Security CCTV Camera $22.90 |
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Replacement Pinhole Fixed Iris Lens for C mount Camera $4.85 |
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9-22mm Zoom CCTV Video Security IRIS Camera Lens $21.83 |
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2.8-12mm Security Camera Wide Angle Zoom Auto Iris LENS $17.99 |
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F1.4 25mm CS Mount Manual IRIS Lens for Security Camera $17.90 |
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Replacement Black 4mm Fixed Iris Lens for CCTV Camera $5.72 |
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6-15mm Manual Iris Zoom, Varifocal CCTV Security Camera Lens FREE SHIPIPNG $29.99 |
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12-30mm ZOOM Manual Iris, Surveillance Varifocal CCTV Security Camera Lens $42.99 |
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6-15mm Auto-Iris, Varifocal CCTV Security Lens $37.99 |
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Super Zoom 6-60mm Auto-Iris CCTV Security Camera Lens FREE SHIPPING $59.99 |
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Ultra Zoom 5-100mm Auto-Iris CCTV Security Camera Lens FREE SHIPPING $93.99 |
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2.8-10mm MTV Mount CCTV Lens Manual Focus IRIS $8.99 |
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Vari-Focal 6~60mm 1/3 Auto Iris CS mount DC Drive Lens for Security CCTV $48.89 |
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Vari-Focal 5~100mm 1/3 Auto Iris CS mount DC Drive Lens for Security CCTV $58.89 |
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CS F1.6 Aperture 4mm IR Fixed Iris Lens for CCTV Camera $6.85 |
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2.8mm-10mm CS Auto Iris Lens for CCTV Video Camera New $20.50 |
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Smart Design Gyral 1/3″ 8mm Iris F1.2 CCTV Camera Lens $6.55 |
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Rainbow L3.5-8mm 1:1.8 1/3″ Auto Iris CS-Mount Lens $49.95 |
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Surveillance 2.8mm F1.2 Fixed Iris Lens for CCTV Camera $9.27 |
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New Auto IRIS 5 ~ 100 mm CS Mount cctv lens $29.99 |
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New Auto IRIS 6 ~ 15 mm cctv lens $12.99 |
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8mm Fixed Iris F1.2 CS Mount CCTV Camera Lens 1/3″ $6.51 |
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Box Surveillance Camera SONY CCD Day Night 6-60mm Varifocal Lens Auto IRIS CHR $159.98 |
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3.7mm Focal Length 1/3″ Format Pinhole Fixed Iris Lens $4.66 |
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600TVL Sony Camera Dual power Auto Iris Lens + BNC for surveillance use-50I $90.50 |
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CS Mount 6mm Focal Length Fixed Iris Lens for CCTV Camera $7.93 |
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CCTV Camera Replacement CS Mount 16mm Fixed Iris Lens $11.25 |
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PHILLIPS AUTO-IRIS CS MOUNT VARAFOCAL LENS $20.00 |
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2.8mm F1.2 Replacement CCTV Camera Fixed Iris Lens $8.79 |
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16mm Auto Iris CCTV Lens For CS Camera True F1.2 U2S $18.00 |
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6mm Auto Iris CCTV Lens For CS Camera True F1.2 U2S $13.00 |
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High Quality 3.5mm-8mm Auto IRIS CCTV Camera DC Lens U2S $19.00 |
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Sony 1/3 CCD Std Box Camera w/3.5-8mm auto-iris lens U2S $48.00 |
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1/3″ F1.4 CS Mount 2.8-12mm Auto-IRIS Varifocal Lens $23.99 |
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3.5-8mm MTV Lens Auto IRIS for CCTV Board PCB Camera $18.50 |
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F1.8 4mm IR Fixed Iris Lens for CCTV Security Camera $7.37 |
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4mm Fixed Iris IR Infrared Lens 1/3 CS F1.2 CCTV Camera $7.99 |
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2pcs New 1/3″ CS manual IRIS 3.5-8MM CCTV Lens for color B/W Camera $19.90 |
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2.8-9mm Auto IRIS Varifocal Zoom Lens For CCTV Camera $26.98 |
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2.8-10mm Auto IRIS Varifocal Zoom Lens For CCTV Camera $32.99 |
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CCTV 600TVL 3.5-16mm auto iris Korean lens Outdoor Surveillance IR Camera OSD $175.00 |
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4MM 4 MM CCTV Lens CS Fixed-Iris f Surveillance Camera $6.99 |
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1/3” 9mm-22mm CS Manual IRIS Manual Focal LENS $25.50 |
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3.5-8mm CS Mount CCTV Lens Manually Focus IRIS $14.49 |
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1/3″ F1.6 Fixed IRIS 6mm Lens for Security CCTV Camera $11.98 |
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3.5-8mm Auto IRIS Varifocal Zoom Lens For CCTV Camera $14.58 |
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5,3.5-8mm Auto IRIS Varifocal Zoom Lens For CCTV Camera $69.99 |
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1/3″ F1.4 CS Mount 2.8-12mm Auto-IRIS Varifocal Lens $23.99 |
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2.8mm F1.2 Replacement CCTV Camera Fixed Iris Lens $9.30 |
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CCTV Camera Replacement 4-9mm Manual IR Board Iris Lens $12.56 |
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PANASONIC PLZ27/5DN CS MOUNT VARI-FOCAL LENS W/ AUTO IRIS DC, 2.7-13.5mm $50.00 |
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Manual Iris 6-15mm Zoom CCTV and Video Camera lens 1/3″ for Surveillance camera $9.99 |
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CCTV Camera CS Mount 12mm Focal Length Fixed Iris Lens $7.94 |
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CS PINHOLE CAMERA LENS MANUAL IRIS 2.8MM WIDE ANGLE $89.99 |
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Super WDR Mini Camera 3.5-8mm Auto IRIS Lens OSD 650TVL $94.99 |
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600TVL Nextchip CCD Color Board Camera w/4~9mm Auto IRIS Lens OSD Menu D-WDR $50.50 |
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Samsung SCC-130 Color Camera w/ 7-70 mm Auto Iris Lens C/CS & Ext.Housing $57.00 |
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700TVL SONY Effio-E DSP CCD CCTV Security Box Camera 2.8-12mm Auto-Iris Lens $89.29 |
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Ultrak Color CCTV Camera w/ 5.5-33mm auto iris lens & 1 New Mount $45.00 |
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NEW BOSCH NDC-265-P IP DOME 720p HD, COLOR, 2.7-9 MM DC IRIS VF LENS, 4GB MICRO $349.95 |
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CS Mount Focal Length 8mm Fixed Iris Lens for CCTV Camera $8.31 |
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Computar TG3Z2910FCS 2,9-8.2mm 1/3″ Auto Iris CCTV Lens ***NEW in BOX*** $29.99 |
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Panasonic WV-CW504 Dome Security Camera | 3.8 ~ 8 mm Auto Iris Lens Surface Mnt $31.51 |
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4 – 10MM DC auto iris CCTV Camera Mega-pixel IR Lens $64.55 |
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CCTV Safety Camera 12mm 1/3″ Format IR Fixed Iris Lens $8.14 |
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EYEMAX CCTV Lens Auto-Iris Varifocal LA TP 358AVF $28.00 |
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EYEMAX CCTV Lens Auto-Iris Varifocal LA TP 615AVF $28.00 |
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EYEMAX CCTV Lens Auto-Iris Varifocal LA EM 358AVF $47.00 |
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700TVL SONY Effio-E DSP CCD 2.8-12mm Auto-Iris Lens CCTV Security Box Camera $92.14 |
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Pentax TV Zoom Lens 8-48mm 1:1.0 Auto-Iris TV Lens – C Mount $79.99 |
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PANASONIC WV-LA4R5A SUPER WA LENS 1/2″ AUTO IRIS 4.5mm $99.95 |
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PANASONIC WV-LM4R5A 1/2” Standard Fixed Iris Lens $69.99 |
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Costar CCC3400 CCD COLOR CAMERA 3.0-8.0mm Auto-Iris Lens $9.94 |
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Costar CCC3400 CCD COLOR CAMERA 3.5-8.0mm Auto-Iris Lens $9.94 |
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Costar CCC3400 CCD COLOR CAMERA Aspherical 2.5-10.0mm Auto-Iris Lens $12.38 |
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Costar CCC3400 CCD COLOR CAMERA 2.8-12mm Auto-Iris Lens $12.38 |
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Costar CCC3400 CCD COLOR CAMERA 5.5-33mm Auto-Iris Lens $12.38 |
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Burle B&W security camera w/ 8.5mm auto-iris lens P $89.99 |
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CA2806SA – Auto Iris, Varifocal Lens 4-9mm, 520TVL $72.00 |
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3.5-8mm Camera CCTV Video Varifocal Mount DC Iris Lens $24.34 |
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Philips BURLE LTC 3361/60 CAMERA LENS MANUAL iRiS $14.95 |
