Per­fectly cor­rected

We all want to get ex­cel­lent per­for­mance from our lenses, but even the very best glass re­quires a lit­tle help­ing hand in post-pro­duc­tion. Martin Evening ex­plains how

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martin evening ex­plains how to get the most from your lenses with some post-pro­duc­tion help

We all want to get the best per­for­mance from our lenses. You can do so by se­lect­ing the op­ti­mum lens aper­ture for best im­age sharp­ness and care­ful fo­cus­ing, but nei­ther of these strate­gies can help you com­bat the ef­fects of vi­gnetting, op­ti­cal dis­tor­tion or chro­matic aber­ra­tions. As with ev­ery­thing, you mostly get what you pay for. With the more ex­pen­sive lenses you should ex­pect to achieve more or less dis­tor­tion-free re­sults with limited vi­gnetting, but even the best lenses can use some help at the im­age-pro­cess­ing stage to per­fect the op­ti­cal im­age qual­ity.

When the Lens Cor­rec­tions fil­ter was first in­tro­duced in Pho­to­shop, you could make man­ual slider ad­just­ments to vis­ually cor­rect an im­age. This fil­ter then got up­dated when Cam­era Raw and Light­room in­tro­duced the con­cept of pro­filed lens cor­rec­tions, which al­low you to cor­rect ei­ther in Cam­era Raw, or later in Pho­to­shop. These days it makes most sense to ap­ply lens cor­rec­tions as early as pos­si­ble in the im­age-edit­ing pipeline. There­fore, when pro­cess­ing your raw cap­tures it is best to use the Lens Cor­rec­tions panel in Cam­era Raw. How­ever, there are times (such as in the video file ex­am­ple on page 36), when the Pho­to­shop Lens Cor­rec­tions fil­ter can still prove use­ful.

Cor­rect­ing a raw im­age is mostly quite sim­ple. All you have to do is open the photo in Cam­era Raw and click ‘En­able Pro­file Cor­rec­tions’ in the Lens Cor­rec­tions panel Pro­file tab sec­tion. Pro­vid­ing there is a lens pro­file in the Cam­era Raw database that matches the lens used to take the photo, Cam­era Raw au­to­mat­i­cally cor­rects the im­age. Lens pro­file cor­rec­tions con­sist of two main com­po­nents: a ‘Dis­tor­tion’ cor­rec­tion to cor­rect for bar­rel or pin­cush­ion geo­met­ric dis­tor­tion and a ‘Vi­gnetting’ cor­rec­tion to cor­rect for light falloff to­ward the cor­ners of the frame. When you ap­ply

an auto lens cor­rec­tion to an im­age, the EXIF meta­data in­for­ma­tion is used to au­to­mat­i­cally se­lect an ap­pro­pri­ate lens pro­file in the Lens Pro­files sec­tion be­low. For this to hap­pen the EXIF cam­era and lens meta­data must be present. If not, you can man­u­ally en­ter the details in this sec­tion. If there are none avail­able it may mean that Adobe have yet to add a lens pro­file for your lens to the Cam­era Raw database. But fail­ing that, it is al­ways pos­si­ble to cre­ate your own (see ‘Cre­at­ing your own cus­tom pro­files’ on page 37). Lens pro­files can con­tain the in­for­ma­tion needed to cor­rect for lat­eral chro­matic aber­ra­tions, but Cam­era Raw now ig­nores such data. There­fore, when the ‘Re­move Chro­matic Aber­ra­tion’ box is checked this ap­plies a cor­rec­tion based on an anal­y­sis of the im­age, rather than ref­er­enc­ing the pro­file data. The lens Cor­rec­tions panel Man­ual tab con­trols pro­vide back­ward com­pat­i­bil­ity, as well as pro­vid­ing con­trols to counter the ef­fects of ax­ial chro­matic aber­ra­tions.

There aren’t any down­sides to ap­ply­ing lens cor­rec­tions to your im­ages. The only time when you might not want to do so is if you wish to preserve the geo­met­ric dis­tor­tion char­ac­ter­is­tics, such as when us­ing a fish­eye lens. Or, per­haps you might pre­fer the lens vi­gnette dark­en­ing to­wards the edges of the frame? It is not just Adobe soft­ware that can be used to ap­ply lens cor­rec­tions. DxO was one of the first com­pa­nies to of­fer lens cor­rec­tion con­trols us­ing DxO Viewpoint.

Use the Lens Cor­rec­tions panel in Cam­era Raw at the be­gin­ning of your raw pro­cess­ing work­flow

Martin is a pho­tog­ra­pher with a com­mer­cial back­ground in beauty photography. He is known for his in-depth knowl­edge of Pho­to­shop and Light­room and as an au­thor on dig­i­tal imag­ing. In 2008, Martin was in­ducted into the NAPP Pho­to­shop Hall of Fame in Las Vegas. His re­cent books in­clude Pho­to­shop CC 2018 for Pho­tog­ra­phers and The Adobe Pho­to­shop Light­room Clas­sic CC Book. Visit www.pho­to­shop­for­pho­tog­ra­

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