The big­gest prob­lem with wide- an­gle lenses is dis­tor­tion. Thank­fully, mod­ern edit­ing soft­ware is up To The Task…

Digital SLR Photography - - The Beginner ’s Guide -

There are two types of dis­tor­tion that oc­cur in pho­tog­ra­phy: op­ti­cal and per­spec­tive, and both are preva­lent when us­ing wide- an­gle lenses in par­tic­u­lar. op­ti­cal dis­tor­tion is an in­her­ent is­sue with wide- an­gle lenses, and man­i­fests it­self in three forms – bar­rel, pin­cush­ion and wavy dis­tor­tion. Bar­rel dis­tor­tion is the more com­mon kind as­so­ci­ated with wide- an­gles, and oc­curs when the im­age ap­pears to fall back at the edges of the frame, and bulge for­ward in the cen­tre. when it comes to more ex­treme ul­tra wide- an­gle and fish- eye lenses, curvi­lin­ear lenses tend to pro­duce very pro­nounced bar­rel dis­tor­tion, with rec­ti­lin­ear lenses less so. Pin­cush­ion dis­tor­tion is more com­monly as­so­ci­ated with tele­photo lenses, and looks the op­po­site – the im­age re­cedes in the cen­tre and ap­pears closer at the edges. wavy dis­tor­tion is a com­bi­na­tion of the two, and is the trick­i­est kinds of op­ti­cal dis­tor­tion to con­tend with. all three are a re­sult of op­ti­cal de­sign and are al­most un­avoid­able in lens man­u­fac­ture, es­pe­cially with wide- an­gles. while big, heavy and ex­pen­sive prime lenses tend to handle op­ti­cal dis­tor­tion bet­ter than bud­get zooms, it’s an is­sue that can be eas­ily cor­rected in post- pro­cess­ing.

Per­spec­tive dis­tor­tion, on the other hand, isn’t unique to lenses, and is vis­i­ble with our own eyes. this oc­curs when ob­jects closer to us, or the lens, ap­pear larger than ob­jects fur­ther away – our brains au­to­mat­i­cally know to trans­late this in­for­ma­tion into depth. when pho­tograph­ing close- up ob­jects with a wide- an­gle lens, the ef­fect is the same, ex­cept the in­creased per­spec­tive of the lens ex­ag­ger­ates things. one com­mon ex­am­ple is when you pho­to­graph a tall build­ing from up close – the build­ing will ap­pear wider at the bot­tom than at the top, and the sides will con­verge to­wards each other the taller the build­ing climbs away from you. this can also be cor­rected in pro­cess­ing, to a cer­tain ex­tent pro­vid­ing the ef­fect isn’t too pro­nounced. there are also spe­cial­ist wide- an­gle lenses avail­able known as tilt- shift lenses, which al­ter the fo­cal plane of the lens in re­la­tion to the sub­ject, help­ing to cor­rect the is­sue op­ti­cally rather than dig­i­tally.

1 open your im­age load your raw file into your cho­sen edit­ing soft­ware – we’re us­ing adobe light­room. most mod­ern lenses and cam­eras em­bed data into the file, so the soft­ware knows what kit the im­age was shot with. some soft­ware, such as affin­ity photo, ap­plies dis­tor­tion cor­rec­tion by de­fault. dis­tor­tion cor­rec­tion can be ap­plied to Jpegs too, but needs to be done man­u­ally.

2 AP­PLY PRO­FILE To ap­ply the pro­file lens corrections, scroll down to the Lens Corrections tab and tick En­able Pro­file Corrections. The cam­era and lens pro­file should be dis­played be­low in the menus, but if it isn’t, you can select it your­self from the lists. Ei­ther way, you can then use the Dis­tor­tion and Vignetting slid­ers be­low to con­trol how much cor­rec­tion is ap­plied ( 100 is de­fault).

3 MAN­UAL COR­REC­TION If your cam­era and/ or lens isn’t recog­nised or sup­ported in the list, then you can still cor­rect dis­tor­tion man­u­ally. Tick the Con­strain Crop box and then use the Dis­tor­tion Amount slider to re­move the bar­rel dis­tor­tion – you’ll need to judge it by eye. Use the tog­gle switch on the Lens Corrections tab header bar to switch the ef­fect on and off and see the dif­fer­ence eas­ily.

4 FI­NAL TOUCHES Fi­nally, use the De­fringe and Vi­gnette con­trols to fix any fring­ing and dark­en­ing of cor­ners. The De­fringe Color Se­lec­tor is sim­i­lar to the White Bal­ance eye­drop­per – sim­ply select the tool, zoom right in, and click on an area of colour fring­ing that you wish to re­move. Easy as that. The Vi­gnette con­trols can be used to re­move dark­ened edges, or add a vi­gnette for cre­ative ef­fect.

Cor­rected re­mov­ing dis­tor­tion here, we've cor­rected bar­rel dis­tor­tion, colour fring­ing and vignetting in just a few steps.

orig­i­nal Above & right: no­tice how the trees seem to bow slightly above? That's a tell- tale sign of wide- an­gle lens dis­tor­tion.

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