Olympus 75 f1.8 potential problem with aperture blades - help

Ricoh

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Having recently bought a second hand Olympus 75 f1.8, I think I may have noticed a possible issue with the aperture blades, possibly sticking, but I'm uncertain and seek your advice please.
I've noticed a clicking sound now and then, and when I look I can see the blades in a partially closed position. But pressing the release button half way, the blades fully open, but return to their partially closed position when the shutter button is released. Switching the camera off and on clears the 'apparent' fault, but it does return periodically.
Any ideas, anything I can do to help diagnose the problem.
I've not seen this with any other m4/3 lens I own.
Cheers.
 

zensu

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I just tried out my refurbished 75 f1.8 on my E-P5 and the aperture blades remain fully open on a half press of the shutter button and only close upon a full press of the shutter button. I only hear one very faint click holding the lens to my ear and it is just the IBIS turning on with the half press because I can immediately hear the whisper sound of the IBIS running after the very faint click sound.
 

bg2b

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Likely the camera is just trying to reduce the amount of light hitting the sensor during live view because it thinks the conditions are a bit bright. When you half press, the camera has to focus with the lens wide open so it opens the aperture again. If you switch to aperture priority, activate the depth-of-field preview, and adjust the aperture, you should see the aperture adjusting as expected. In other words, I don't think there's any problem.
 

Bif

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I've noticed similar behavior on several of my Lumix and Oly lenses. It seems to be normal and I don't think you have a problem. That 75mm is one heckuva nioe lens, I love mine.
 

Ricoh

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Thanks to all.
Now you mention the conditions, it was rather bright daylight when I noticed the aperture blades 'half' closed, this could very well explain the situation.
I almost always work in aperture priority, but have to confess not using depth of field preview. How do I enable this? Perhaps I do this already but I'm unaware of my 'skills'.
Many thanks,
Steve.
 

eteless

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It's normal in brighter conditions to prevent the sensor heating up. Generally one of the smaller front buttons between the sticky out grip part and the lens will be dof preview, if not you can rebind it in the key bindings menu (should be the bottom right option on the SCP).

...actually has the E-M5 got a front button? I'm not sure :S pictures don't seem to show one, so you might need to use a rear button. I haven't used the E-M5 as I stuck with an E-5 til the E-M1 came out.
 

pdk42

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Steve - this behaviour is completely normal. As other posters have pointed out, it's the camera stopping down in Live View when the light's bright. It's not always consistent though I've found. You'll get it with other lenses too. The Pany 25 is infamous for the noise you get when it happens. It's often referred to as "rattle-snaking".
 

Fri13

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You didn't mention what is your camera. Have you check do you have a anti-flicker function enabled / auto? As that does cause apeerture to be changed in live view while disabling it will keep aperture always fully open until exposure or when focusing (to get enough contrast if too bright scenery and overexposing)
 

Ricoh

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I'm really pleased to have this explained, good to know I haven't got a duff lens :) It sure is a cracking lens after all.
Although the gain could be turned up or down according to the light level instead of adjusting the aperture during live view, there must be some subtle reasoning to use an electro- mechanical solution instead of micro second response of electronics.
 

Ricoh

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Just noticed your reply Fri13, which I thank you for.
You're right, I didn't mention the camera being used. Although I have an EM5 and an E-P5, it was with with the E-P5 I noticed the aperture blades closing during live view. I thought at the time the blades had stuck partially closed/open from the previous shot, but now it has been explained.
I'll have to look at the 'anti-flicker' setting, any clues please on menu I should be looking at. User manual is diabolical, good if you're using for reference, but not for instructional purposes.
 

Ricoh

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Thanks Paul.
What a great forum this is - helpful individuals ready to provide answers on almost every question concerning Mu43 photography and equipment!
 

zensu

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Sorry about my earlier post but I was not in sunny conditions at all. It's been raining here for two days with no sun in sight. I had a very similar experience with my E-M5 and a Panny/Leica 25mm f1.4 and setting flicker reduction helped a lot. As soon as the sun returns I'll check it out in bright light. I'm sorry if my earlier post spooked you!
 
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