Digital SLR Photography

Nove mber2016Digital slr Photography 75TheBeginner’sGuideAll DSlRS SuffeR from noise tovarying degrees, and thisreducesimage quality, especially in the shadowareas. fortunately, your camera has noisereduction settings to help solve thisproblem. There are two typesof noisereduction–long exposure and High ISO.Both are turned On/Off via the camera’smenus and may have different settings suchas low and High, depending on the exactmodelof DSlR that you're shooting with.HigH iSO NR:If youshootathighISOtherearetwotypesofnoisecreated–luminanceandChrominance.Theformeristhegrey/blackgrainyeffectyouseeintheimages,andthelatterconsistsofcolouredspeckles,usuallyvisibleinthemidtonesandshadows.In-camera high ISO NR tends to mainlyreduce Chrominance noise as it doesn’taffect subject detail so much. luminancenoise doesform subject detail, so if youremove it the shot tends to look too smoothand lacks detail. If your DSlR has differentsettingsfor High ISO NR, the lowest willremove Chrominance noise but the highestor strongest will alsoattack luminancenoise, so you need to use it with caution,otherwise fine detail can be destroyed andthe image will look odd.The important thing toremember is thatwhile noisereduction is added to imagesin-camera if you shoot in JPeGformat, it’susually only applied to Raw files if youprocess those files using the camera’smakers Raw software –ACR in Photoshopand lightroom won’trecognise it, so there’sno point applying it in-camera. Instead, youcan add noisereduction when you processthe Raw files – inACR there are two slidersfor this purpose. The luminance sliderconcentrates on greyscale noise while theColor slider deals with Chrominance noise.experiment with different levelsfor bothsliders and don’t beafraid to push them bothall the way to 100 if you want to get ridof asmuch noise as possible. The downsideofdoing this is that there will be lossof details,but the pros are likely to outweigh the cons ifan image is particularly noisy, and it may alsohelp toreduce the appearanceof artefacts ifyou over-sharpen.Another option is to turnoff any noisereduction in your camera and Rawprocessorthenusenoisereductionsoftwaresuch as Dfine 2, which is partof the superbNik Collection, nowavailable freeof chargefrom http://www.google.com/nikcollection.LONg ExpOSuRE NR:As the name implies,this is designed toreduce the noise you getwhen you use long exposures to makeimages – either because you’re shooting inlow light, or using an extreme ND filter likethe lee BigStopper to increase theexposure. The longer you leave the camera’sshutter openfor, the warmer the sensor getsand some pixels start to get hot. Thisresultsin white or coloured dots appearing in yourimages. They’re particularly obvious in darkareas, such as shadows or the night sky.If you turn on your camera’s longexposure NR, as soon as the shutter closesat the endof the picture-taking exposure,asecond closed-shutter, dark frame,exposure is madefor the same duration asthe previous exposure. This is done so your``````camera can map the noisy pixels in the firstimage andremove them from the originallong exposure image.longexposureNRworksreasonablywell,butit’sfrustratingtousebecauseifyoumakeafive-minuteexposure,youthenhavetowaitanotherfiveminuteswhiletheclosed-shutterexposureismade.Consequently,themajorityofphotographersturnitoffanddealwithlongexposurenoiseinpost-production.``````Top:HighISOnoisereductioncanbeusedtoreducethegraineffectcausedbyshootingathighISOs.Above:LongExposurenoisereductionhelpseliminatehotpixelscausedbylongexposures,butcanbefrustratingtouse.``````ImAGeS: lee fROSTNOiSE REDuCTiONHigH iSO NR``````LONg ExpOSuRE NR