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Focus problems - any tips?

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Janine78

Ny medlem
Hi,

I'm writing this in English because otherwise it'll take me all day to try to get the Swedish right. Feel free to reply in Swedish though.

I have a Canon 6D with some quite new Sigma lenses (Art 50/1,4, 35/1,4 and 85/1,4). I had some focus problems a while ago so I sent everything away and had the lenses calibrated. Everything seemed to be better, but I've noticed now that the focus is just not right again (or still?). I have the best rate of success with the 35, and the least success with the 85. Sometimes it's fine, but it seems to be hit and miss.

The problem could very well be me, but sometimes even in quite straightforward situations, the focus seems to be off and I feel like I can't just keep blaming myself now. I've made sure the shutter speed's fast enough to ensure that the problem isn't motion blur. I've tested different apertures to make sure the problem wasn't that the depth of field was too shallow and I've missed focus. I've also tested with low ISOs, so the problem isn't grain. I toggle my focal points, so I'm not focusing and recomposing.

Any tips?

Is it possible that the lenses need to be checked again?

I know my camera body is overdue for a clean. Could that cause problems like this?

Would back-button focusing make a difference?

Is there something really obvious that I'm missing?

There's a risk that this is something really basic that I shouldn't need to ask about, but I feel so frustrated now that I need help from the outside.

Thanks.
 

JNES

Ny medlem
Jag skulle kolla samma linser med ett annat kamerahus. Kan faktiskt vara själva kameran. Sedan skulle jag ta testbilder med en eller ett par originallinser med din D6:a. En bra fotoaffär kan säkert hjälpa till.
Ibland kan det vara så att ett lite dyrare hus inte går bra att använda med andra linser än originallinser men jag skulle börja med ovanstående!

Mvh

Johan
 

Janine78

Ny medlem
Jag skulle kolla samma linser med ett annat kamerahus. Kan faktiskt vara själva kameran. Sedan skulle jag ta testbilder med en eller ett par originallinser med din D6:a. En bra fotoaffär kan säkert hjälpa till.
Ibland kan det vara så att ett lite dyrare hus inte går bra att använda med andra linser än originallinser men jag skulle börja med ovanstående!

Mvh

Johan
Tack för tipset, Johan. Jag börjar med det då.
 

J O Härnström

Aktiv medlem
Sigmas nya ART-serie fokuserar mer exakt än tidigare modeller.
Att fokusera exakt med väldigt ljusstarka objektiv kan vara svårt eller omöjligt vid väldigt hög kontrast i motivet.
Jag märker med min EOS 5D Mark III att fokus kan hamna fel när det är hög kontrast med solblänk eller i motljus. Objektivet är ett nytt 50mm/1,4 Art och i "vanliga" ljusförhållanden sitter skärpan perfekt.
 

FlyerOne

Aktiv medlem
It MAY be an uncertain factor that you have access only to third party lenses (and from the same vendor only). Is it possible for you to check out the AF performance with a Canon wide aperture lens?


--- I toggle my focal points, so I'm not focusing and recomposing. ---
The AF points in many/most cameras are not equal. Expect to get the best AF performance when using the center AF point. Regarding EOS 6D, I have seen some posts saying that the surrounding AF points are not so great.


--- Would back-button focusing make a difference? ---
No.
 
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