HELP!! oil on diagphram blades

andytaff

andytaff

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Hi Guys,
got a problem and i hope some one can help, i've got oil on the diagphram blades of my minolta af 50mm lens,which is causing it to over expose even at f22.The blade still move but, too slowly.
This is one of my favourite lens so if theres any chance of saving it !!
cheers for any advice or help
Andy
 
Easy answer is don't use f/22. You'll get very poor sharpness due to diffraction at that high an f/number anyway. On a crop camera I wouldn't go above f/11 unless absolutely essential

It's not uncommon to get innacurate/inconsistent exposures at high f/numbers as a tiny amount of mechanical inaccuracy can make a big difference there.

It's perhaps quite an old lens? Should be an easy service job to bring it right up to spec.
 
You'll need to get it serviced. It's often an easy enough job for a technician to clean the oil off the diaphragm. However, as it can entail a total strip down of the lens, you may want to get a solid quote from them before handing the lens in -it's potentially a time consuming job depending on lens design.
 
Hi Hoppy uk,
it's not that i'm using F22, it's that it's still wide open and over exposing because it's not closing to a small app. no matter what f stop i use so i can no longer use it for studio work. It'll be fine for shallow dof and fast shutter speeds but, i love this lens for portrait work
Andy
 
thanks Cuchulainn,
is this a send away job or can i get it done in jessops or jacobs?
cheers Andy
 
Sorry I didn't get back before now. I doubt Jessops or Jacobs could do it - worth setting up a thread asking people for recommendations for lens repair places to send it to!
 
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