swi Posted June 23, 2011 Share #1 Posted June 23, 2011 Advertisement (gone after registration) I have fitted a Kiwi filter adapter so that I can use 49mm filters etc. I intend to keep a UV filter fitted permanently on the lens. My worry is - the adapter and filter are a tight fit. When the lens extends it is like a piston inside the sealed adapter. Where does the air go? Could it blow back towards the sensor? I was toying with the idea of drilling a small hole in the adapter tube for pressure relief. Anybody have any data/opinions, please? Link to post Share on other sites More sharing options...
Advertisement Posted June 23, 2011 Posted June 23, 2011 Hi swi, Take a look here Filter adapters - air pressure?. I'm sure you'll find what you were looking for!
earleygallery Posted June 23, 2011 Share #2 Posted June 23, 2011 More like a piston without a piston ring. The camera isn't sealed - see threads about dust on sensors. Actually, keeping the ring and filter on all the time should prevent dust working its way onto the sensor. Link to post Share on other sites More sharing options...
mjh Posted June 23, 2011 Share #3 Posted June 23, 2011 My worry is - the adapter and filter are a tight fit. When the lens extends it is like a piston inside the sealed adapter. Where does the air go? Could it blow back towards the sensor? When the lens extends it sucks in air, in this case the air that fills the space confined by the adapter and filter. When it retracts this air is released again into the adapter. Even when the camera was sealed air-tight there wouldn’t be any issues. If, on the other hand, the telescoping tubes of the lens where sealed air-tight then the lens could neither extend nor retract; the air pressure inside or outside the lens would prevent that. Link to post Share on other sites More sharing options...
swi Posted June 23, 2011 Author Share #4 Posted June 23, 2011 Many thanks to both posters above. Yes, I get it now! It is now obvious that the lens sucks and blows air that is already contained in the adapter tube. But if that air flow is restricted by the adapter, would more air flow through the camera?. Whether this would cause a problem with dust on the sensor depends on how well the sensor is sealed in the camera. If the rear element of the lens is fixed, then there could be an airtight seal there. I was worried that there might have been a problem with dust, but thinking about it, there would be a worse possible problem with the lens exposed. As the poster above implied, keeping the lens in a filter/adapter enclosure should in fact reduce possible dust problems, unless, of course, the restriction on air flow at the front causes more air to travel through the body.... Thank you for clarifying my thought processes! Link to post Share on other sites More sharing options...
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