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Pistill um SKERPU
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Micaya


Skráður þann: 17 Des 2009
Innlegg: 4998


InnleggInnlegg: 20 Jan 2011 - 8:29:35    Efni innleggs: Pistill um SKERPU Svara með tilvísun

Mér fannst þessir tveir pistlar vera alveg þess virði að deila með öðrum hérna, ekki síst vegna þess að stundum virðast umræðurnar snúast meira um græjukaup en ljósmyndun í sjáfri sér. Ok með það, en til að vega pínu á móti langar mig að pósta þetta.
Það er nú ekki meira afrek hjá mér en copy-paste, hehe...
Endilega kommentið ykkar reynslu á fókus og skerpu, annars hverfur þetta af spjallborðinu allt of fljótt Smile

(Sitt hvor þráður fyrir pistlana)

--------------------

UM SKERPU



One very common question I get from photographers is why they can never get their images as sharp as the ones they see online. This is a loaded question, and it really made me think about all the things I go through to get tack sharp focus on my images. Sure there are the obvious tips like holding the camera properly, squeezing the shutter instead of stabbing it, tucking your elbows in, and so on. The truth is, that is just the beginning to taking sharper photographs.

Let me start off by saying that I still take blurry images from time to time. All professional photographers do. The only difference is that we don’t post them online! However, I will also bet that I take far less than most other photographers, and there are clear reasons as to why. Getting sharp images involves a combination of a few different techniques, and when put together they will produce a far higher success rate of sharp images.




Back Button Auto-Focus
I can honestly say that about 90% of the photographers I talk to don’t use this built in feature on almost all cameras. Whenever I ask photographers how they focus on a subject, the response is that they press the shutter half way down to focus, then all the way down to take the picture. The problem with this is that EVERY time you take a picture, your camera is going to re-focus the frame. What if your subject is a far away person and there is a crowd of people walking between you? You can’t just set your focus distance and fire away. Instead you have to wait for line of site to your subject and hope nobody walks by while you focus each time.

On most (nearly all) cameras, there is a button on the back of the camera titled “AF On.” Through your menu settings, you can set this button as your focus trigger. This way, you set your focus then fire off as many shots as you need to. The focus point stays the same through all shots and the shutter is free to be used as just that, a shutter.




Single Point AF
One of the many revelations that photographers have is discovering the difference between letting your camera decide how to do something, and telling your camera what to do. Most photographers press their shutter down halfway and the camera decides what to focus on. More often than not, it picks the right thing. This is normally because the subject is prominent in the frame and the camera can easily find a contrasting element to focus on. Using this simple method is fine in a lot of cases, but if you begin to venture into prime lenses and shallow depth of fields, your images will begin to suffer greatly.

If your subject is 10 feet away and you’re shooting f/2.8 at 200mm, your depth of field is only 1 1/2 inches deep! That means that your subject will come into focus at 9.94 feet away, and drop out of focus at 10.06 feet away. Do you want to leave a 1.5 inch depth of field up to your camera? What if it focuses on the tip of the nose? Now your subjects eyes are out of focus.

Your camera should have a button (top right in image) that shows how the camera is focusing. The default is to have all the focus points on and the camera uses those points to decide where to focus. Instead, press the focus grid button and use the joy stick (bottom left in image) to decide where to set your focus point. Instead of a bunch of focus points popping up when your go to focus your subject, you will now only see the single focus point that you set. Now if you want to focus on your subjects eye, place your selected focus point over the eye and simply tap your AF-ON button. Your focus is now set for that mark in the frame. The only thing you need to worry about now is movement.




AI Servo Focus Tracking
Funny name, serious setting. Getting your camera off of “One Shot” can be revolutionary to your photography if you have yet to discover Servo focus mode. Here’s an example of how Servo works: You’re shooting a wedding during the end of the ceremony. You are at the end of the aisle and the wedding party is walking down toward you. You are shooting at f/2.8 because it’s dark and you want to let in as much light as possible. Your depth of field is 6 inches. With “One Shot,” your camera only focuses on the subject each time the focus button is pressed. You then have to press the shutter to take the picture. With a depth of field of 6 inches, and the wedding party walking towards you in groups of two, your window of opportunity to get your shot in focus is incredibly small. One strategy is to just try and be quick, pressing the focus button and shutter in succession as quickly as possible. Another strategy is to set a mark on the aisle as a window of opportunity and wait for each person to hit that mark, then take the picture. This is hit or miss though, and you only have one chance. You don’t want to take chances like this at a wedding!

Enter AI Servo

When you switch your camera over to AI Servo, everything changes. Servo was introduced as a standard camera setting all the way back in the 80’s, by request of several sports photographers who needed a better way of ensuring focus on moving subjects. With Servo activated, now your camera will track focus on the wedding party as they move toward you, and will keep updating every step of the way. This works whether the subject is coming toward, or moving away from you. In your menu settings, you can even adjust the sensitivity of the focus tracking.

EXAMPLES USING THESE TIPS



This shot is from a meet and greet session with the band Jars of Clay, at a concert in Austin, Texas. The manager told everyone not to worry about taking pictures until after the show because any meet and greet pictures would be boring. I took that as a challenge. I sat patiently for the right moment and when I saw their lead singer make eye contact with my lens, I fired away.

With normal focus methods, this shot may not have been possible, and I don’t like taking chances. If I used grid focus, how would my camera know to focus on HIS face, and not something else in the frame? Instead of using the entire focus grid, I turned on a single auto focus point and placed that point over the lead singers face. I then used my back button to focus that point over his face and waited for the right moment. When he looked my way, everything was already done, all I had to do was hold down the shutter.




This is one of my favorite pictures I’ve taken. It’s my nephew Will being spun around by his dad Billy (my brother in law). I think the image embodies the love between a father and a son, and what better backdrop than fair grounds? With factory set focus methods, the probability of pulling off this shot would have been slim to none. Sure, you can spray and pray, and hopefully you will end up with a keeper, but what if you don’t? The moment is gone! For this shot, I had a single point activated in my focus grid and used AI-Servo to track my nephew as he spun around in circles. Because I had back button auto focus on and Servo tracking, I was able to hold down the focus button to track focus as he spun around. This allowed me to track focus using my thumb and hold down the shutter with my index finger. Trust me, this stuff becomes crucial when you start using shallow depth of field like in this shot.




I took this shot during a family shoot last spring. I was having a tough time getting this little guy to open up to the camera and I had to figure something out quick. I noticed a ledge (as seen in the background) and made a bet with him that there was just no way he could jump off that ledge because it was only for big boys. Well, that was all it took! Within seconds he was up on the ledge with a smile on his face, ready to prove me wrong. Again, I used Servo focus tracking and held it down during the jump using back button focus. I grabbed this frame as he made a bit of a rough landing.




This image was taken at Carlsbad State Beach in southern California. This surfer girl noticed my camera and came running up the beach to greet me and talk photography. She was also a photog and wanted to make sure I didn’t get a shot of her wiping out! As she walked back out to catch some more waves, I grabbed this shot of her. I placed a single AF point over her back, then held down Servo focus tracking so my camera would keep her in focus as she walked away. When the moment was right, I held down the shutter to capture a hand full of frames. This was the winner.

Conclusion
These focus tips completely rocked my world when I discovered them, and they will always be part of my work flow, now and in the future. I probably use AI Servo about 90% of the time. The only time I don’t is when it’s too dark for the camera to focus without an assist beam from a flash. To use a flashes focus assist grid you have to be in “One Shot” instead of AI Servo (at least as far as I can tell). I don’t see any reason to ever go back to using my shutter button for focusing. I have never looked back on that front! And as far as grid or single point AF goes, it’s pretty much the same story. I use my entire grid maybe 1% of the time.

If these tips are new to you, I urge you to stop what you are doing and give them a shot. I will admit, using back button focus and single AF points takes some getting used to, but eventually it becomes second nature. At this point, I can switch focus points on my grid in the blink of an eye, and using the back button for focus is instrumental in placing those points of focus on their targets.

UPPRUNI: http://www.digital-photography-school.com/advanced-tips-for-tack-sharp-images#ixzz1BYtbNPaI
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Flugufrelsarinn


Skráður þann: 04 Jan 2010
Innlegg: 453

....
InnleggInnlegg: 20 Jan 2011 - 8:58:36    Efni innleggs: Svara með tilvísun

Og núna vantar bara skoðanakönnun, hversu margir noti AF ON takkann fyrir fókusinn Smile
Fyrir mitt leyti hef ég prófað það en nota það ekki. Eftir að hafa lesið þetta langar mig að prófa aftur.
Til baka efst á síðu
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gudmgu


Skráður þann: 14 Okt 2009
Innlegg: 418

Canon
InnleggInnlegg: 20 Jan 2011 - 9:01:55    Efni innleggs: Svara með tilvísun

Flott grein takk firir. Nú verð ég að komast að því hvort mín vél stiður Back Button auto-focus
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raggos


Skráður þann: 01 Feb 2009
Innlegg: 605
Staðsetning: Kópavogur
....
InnleggInnlegg: 20 Jan 2011 - 9:06:56    Efni innleggs: Svara með tilvísun

Flott copy paste Micaya!

Gott að fá svona áminningu um hvernig á að gera hlutina! Smile
Ég vandi mig á að nota af-on takkann þegar ég fékk mér 40D og er í dag algerlega háður því að geta valið fókus punkt hratt með joystick-inu og haldið fókus með AF-ON takkanum.
Ég þarf þó að venja mig á að nota AI Servo oftar. Oft misst af skemmtilegum myndum vegna single shot stillingarinnar.
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Micaya


Skráður þann: 17 Des 2009
Innlegg: 4998


InnleggInnlegg: 20 Jan 2011 - 9:17:46    Efni innleggs: Svara með tilvísun

Flugufrelsarinn skrifaði:
Og núna vantar bara skoðanakönnun, hversu margir noti AF ON takkann fyrir fókusinn Smile
Fyrir mitt leyti hef ég prófað það en nota það ekki. Eftir að hafa lesið þetta langar mig að prófa aftur.

Ég til dæmis hef notað þetta... brrr... einu sinni?? Ég verð að tileinka mér þessar aðferðir, mann langar að ná flottum myndum í fókus og skörpum!!

gudmgu skrifaði:
Flott grein takk firir. Nú verð ég að komast að því hvort mín vél stiður Back Button auto-focus

Emm... er þetta ekki sjarnan * ?
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gudmgu


Skráður þann: 14 Okt 2009
Innlegg: 418

Canon
InnleggInnlegg: 20 Jan 2011 - 9:22:39    Efni innleggs: Svara með tilvísun

það er margt um að velja varðandi þessa stillingu Shocked

One thing to remember is that anything before the slash mark refers to how the shutter button will behave, and anything after the slash mark tells you how the rear button will work if selected.

On the Canon XS

* 0: AF/AE lock
* 1: AE lock/ AF
* 2: AF/AF lock, no AE lock
* 3: AE/AF, no AE lock
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DanSig


Skráður þann: 25 Nóv 2004
Innlegg: 7450
Staðsetning: Reykjavík
iPhone 4s
InnleggInnlegg: 20 Jan 2011 - 9:49:42    Efni innleggs: Svara með tilvísun

þá er bara eftir að þýða þetta á íslensku svo við skiljum þetta Wink við erum nebbnilega íslendingar og tölum ekki úglensku Razz
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innlegg mín endurspegla stundum mína persónulegu skoðun og ber ekki að taka of bókstaflega !
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bjarkih


Skráður þann: 18 Júl 2007
Innlegg: 1287
Staðsetning: Akranes
Canon 5D Mark III
InnleggInnlegg: 20 Jan 2011 - 10:15:48    Efni innleggs: Svara með tilvísun

Takk fyrir að setja þetta inn. Mann langar til að prófa þetta með AF-ON takkann, hef aldrei almennilega kynnst honum.
Eins er maður alltof fastur í One shot, maður á greinilega að nota servoið oftar.
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Canon EOS 5D mark III; Canon EOS 7D mark II; Canon EF 24-70mm f2.8L; Canon EF 70-200mm f2.8L; Sigma 50mm f1.4; Canon EF 85mm f1.2L II; Canon EF 135mm f2L; Canon EF 100-400mm f4.5-5.6L IS II; Sigma 35mm f1.4 Art
http://www.flickr.com/bjarkih/
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Diggler


Skráður þann: 10 Nóv 2008
Innlegg: 1906
Staðsetning: Mitt í Borg Óttans ;)
Auðvita Canon sem aðal ;)
InnleggInnlegg: 20 Jan 2011 - 11:27:21    Efni innleggs: Svara með tilvísun

Frábær grein Smile Ég nota bæði Af-On og nýti líka Al-Servo fókus en alltof sjaldan. Þarf að vera duglegri við Al-Servo en kannski nota ég það lítð vegna þess að ég mynda ekki mikið mannamót og fólk Smile
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Canon Eos 40D,Sigma 18-50mm f/2.8 EX DCl, Sigma Super 500 og Vivitar XV-3 og fleiri linsur fyrir filmurnar..... Smile

www.flickr.com/photos/simmikrimmi/
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garrinn


Skráður þann: 06 Jan 2008
Innlegg: 3619
Staðsetning: Akureyri
Canon EOS 5D
InnleggInnlegg: 20 Jan 2011 - 11:46:11    Efni innleggs: Svara með tilvísun

Hef notað AI-Servo nokkuð, bæði almennt þegar um fólk eða krakka er að ræða, en sérstaklega í Skautamyndatökum og til dæmis í hestamyndatökum.

Það er mikill munur á fókus getu 1DMKIIN og til dæmis gömlu fimmunar. Prófaði aldrei 400D vélina sem ég átti á AI-SERVO (man allavega ekki til þess) en hef lesið á netinu það sé nokkur munur á fókuskerfum þessara véla.

Það er mjög gott að fólk viðurkenni mun á niðurstöðum þess að nota tækin og tæknina á þann hátt sem þau best bjóða upp á, það er allavega fyrsta skrefið við að jarða þessa hreint fáránlegu mítu að góð tæki geri ekkert fyrir ljósmyndara.

Næst er að átta sig á því að sum tæki er betri á sumum sviðum en önnur.

Þessi grein ætti að opna augu einhverra hvers vegna.
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Canon EOS 5D, 1D MKIIn
Myndir stórar - PAD Garrinn
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Matti Skratti


Skráður þann: 12 Nóv 2007
Innlegg: 727
Staðsetning: 27 W 458472 7108076
Skiptir ekki máli
InnleggInnlegg: 20 Jan 2011 - 12:24:07    Efni innleggs: Svara með tilvísun

Afhverju þarf að öskra orðið skerpa???
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HjaltiVignis


Skráður þann: 09 Ágú 2007
Innlegg: 1515

Canon EOS-1Ds Mark II
InnleggInnlegg: 20 Jan 2011 - 12:49:44    Efni innleggs: Svara með tilvísun

Finnst að það ætti að troða AF takkanum á batterygripin líka.
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HjaltiVignis
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BKG


Skráður þann: 18 Maí 2008
Innlegg: 2840
Staðsetning: Ísland
Cannon e-ð
InnleggInnlegg: 20 Jan 2011 - 13:00:45    Efni innleggs: Svara með tilvísun

Greinilegt líka að þessum finnst ekkert betra að hafa 999 fókuspunkta...

Persónulega nota ég alltaf bara einn. Hef prófað að hafa fókus takkann aftan á en greinilega ekki gefið því nógu langan tíma til að venjast.
Greinilegt að maður þarf að príofa AI servo betur/oftar.
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koys


Skráður þann: 26 Júl 2005
Innlegg: 132

Canon 500D
InnleggInnlegg: 20 Jan 2011 - 13:44:58    Efni innleggs: Svara með tilvísun

þarf maður að breyta einhverju í custom functions td í 500d? Ég held að ég hafi gert rétt þegar ég fór í C.fn 10 og breytti í AE lock/AF
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koysone
flickr
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gummio


Skráður þann: 12 Maí 2008
Innlegg: 908
Staðsetning: Reykjavík
Canon 5D Mark II
InnleggInnlegg: 20 Jan 2011 - 17:59:49    Efni innleggs: Svara með tilvísun

Ég ætla að prófa að gefa AF-ON takkanum séns.
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Kveðja,
Guðmundur Ólafs.
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