Preventing sensor dust

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nielsgeode
Posts: 306
Joined: Tue Jul 31, 2012 11:47 am
Location: Groningen, Netherlands

Preventing sensor dust

Post by nielsgeode »

Last year I switched from Canon to Sony a6300 with a Kipon EOS/NEX adapter in which I mounted a UV filter. It keeps the sensor spotless which is really nice with extreme macro stacking. Here you can see how the UV filter is inside the adapter.

I recently purchased a new Sony a7r iii for extra resolution and detail in my stacks. I can use the same adapter, but I also like to have AF and aperture control with my Canon EF lenses. In addition, I like to have it modified for IR photography (and sell my modified 6D). Having a second a7r iii with the Kipon for 'dust-only reasons' is pretty expensive and I'm looking at other solutions to keep my sensor dust-free.

Ideally I find an adapter similar to the Kipon that has lens contacts so I can control aperture and AF with a 'sealed' adapter.

I was looking at this adapter and I estimate the opening where the glass is mounted to be about 3 cm. It looks like the glass can easily be replaced with a high-quality UV filter, but I think the opening is too small to cover fullframe. What's you thought on that?

Looking forward to your thoughts and (alternative) ideas.

Thanks
Niels

RDolz
Posts: 96
Joined: Mon Aug 28, 2017 9:32 am
Location: Valencia (Spain)

Post by RDolz »

Hi Niels, I'm sorry, I can not answer your question,

But what a good idea! I had never seen it before, but it seems like the solution to the problem of avoiding dust on the sensor for those of us who spend our lives exchanging lenses in mirror less cameras. I have to test it.

A question, insert a UV filter has not generated flare or increased aberrations? Have you done any comparative tests with and without a filter?
Ramón Dolz

nielsgeode
Posts: 306
Joined: Tue Jul 31, 2012 11:47 am
Location: Groningen, Netherlands

Post by nielsgeode »

RDolz wrote:Hi Niels, I'm sorry, I can not answer your question,

But what a good idea! I had never seen it before, but it seems like the solution to the problem of avoiding dust on the sensor for those of us who spend our lives exchanging lenses in mirror less cameras. I have to test it.

A question, insert a UV filter has not generated flare or increased aberrations? Have you done any comparative tests with and without a filter?
I have not tested it, but image quality is very good. Use B+W! Not cheap Chinese ;)

I use this adapter and glued a 43-37mm step down filter ring 'upside' down so the male thread is facing the lens. I used Bison epoxy glue designed for glueing metal. It works fine with crop, but gives slight vignetting with fullframe. I think using a 40.5-43mm instead solves that issue. You screw the 43mm filter 'upside down' onto the ring. If you want to make your life more difficult, you an also use an ND filter instead :lol:


For glueing I mixed the 2-component epoxy onto some cardboard with a tooth pic and 'scooped' (via the back) a 2 mL syringe with blunt thick needle (after removing the injection piston form the syringe. With the syringe you can very precisely apply a thin circle of glue in the inside of the adapter and glue the ring onto it. Before doing so, I stacked some more rings so I could more easily handle it and apply some weight onto the stack of rings while the glue hardenes. The next time doing so I will put Teflon tape on the outside to fill the temp so the ring is glued more in the center of the adapter. After the glue sets, the Teflon tape and the stacked rings can be easily removed.

RDolz
Posts: 96
Joined: Mon Aug 28, 2017 9:32 am
Location: Valencia (Spain)

Post by RDolz »

Niels, Thank you very much for your detailed description, I will definitely test it. :lol:

It is a great idea to attach a 43-37mm step down adapter, or similar. This allows, in case the UV filter generates some degradation of the image, keep the original adapter fully functional.

When I mount it I will do some tests and upload them to the forum.
Ramón Dolz

nielsgeode
Posts: 306
Joined: Tue Jul 31, 2012 11:47 am
Location: Groningen, Netherlands

Post by nielsgeode »

RDolz wrote:Niels, Thank you very much for your detailed description, I will definitely test it. :lol:

It is a great idea to attach a 43-37mm step down adapter, or similar. This allows, in case the UV filter generates some degradation of the image, keep the original adapter fully functional.

When I mount it I will do some tests and upload them to the forum.
Looking forward to the results! However, I find it very hard to believe you see any difference at all (except when pixel peeping). Keep in mind that high-end UV filters are expensive and designed to not affect your image. :)

I quoted some random needle listing on Ebay, if you do a search you can find cheaper ones with free shipping.

enricosavazzi
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Joined: Sat Nov 21, 2009 2:41 pm
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Re: Preventing sensor dust

Post by enricosavazzi »

nielsgeode wrote:[...]
I was looking at this adapter and I estimate the opening where the glass is mounted to be about 3 cm. It looks like the glass can easily be replaced with a high-quality UV filter, but I think the opening is too small to cover fullframe. What's you thought on that?
I assume that you are aware that this adapter is a focal length reducer (called speed booster by some manufacturers), and that the optics of the adapter are not a flat glass plate but one or more optical elements with curved surfaces. The thickness of these optics (and consequently their mount in the body of the adapter) may be too high to allow mounting a filter in their place, which would "sit loose" in the mount. Another difficulty is that it may be difficult to find a filter of the exact diameter needed.

As a workaround, it is probably possible to attach an unmounted filter with epoxy or silicone at the front or rear of the adapter, and to find a filter sufficiently large for this while still small enough to sit within the front or rear bayonet. (If using silicone, keep in mind that it may be difficult or impossible to clean it off an optical surface, so the trick is not getting any silicone there in the first place. Easier said than done.)

I also assume that the purpose of the filter is to prevent dust contamination of the camera interior while doing photomacrography. One important thing to remember is that depth of focus (which is measured on the sensor side) is remarkably large in photomacrography. As depth of field (DOF, measured on the subject side) decreases with increasing magnification, depth of focus correspondingly increases. This means in practice that, in photomacrography, dust on a filter located a relatively short distance from the sensor will project a sharp shadow onto the latter. In practice, dust on the filter will have much the same effect as dust on the sensor - unless the filter is several cm from the sensor.

Some digital cameras do (or did) employ a permanent or removable filter in the camera body, mounted some distance from the sensor. I think the Nikon 1 was such an example. This was fine when using the camera for ordinary photography (large DOF and correspondingly small enough depth of focus to hide most dust particle on the filter), but not in photomacrography.

Another potential problem is that under certain conditions light can be reflected multiple times between sensor surface and a flat filter parallel to the sensor, producing image artifacts. A high-quality multicoated filter will be less likely to do this, but it may still happen.
--ES

nielsgeode
Posts: 306
Joined: Tue Jul 31, 2012 11:47 am
Location: Groningen, Netherlands

Re: Preventing sensor dust

Post by nielsgeode »

enricosavazzi wrote:
nielsgeode wrote:[...]
I was looking at this adapter and I estimate the opening where the glass is mounted to be about 3 cm. It looks like the glass can easily be replaced with a high-quality UV filter, but I think the opening is too small to cover fullframe. What's you thought on that?
I assume that you are aware that this adapter is a focal length reducer (called speed booster by some manufacturers), and that the optics of the adapter are not a flat glass plate but one or more optical elements with curved surfaces. The thickness of these optics (and consequently their mount in the body of the adapter) may be too high to allow mounting a filter in their place, which would "sit loose" in the mount. Another difficulty is that it may be difficult to find a filter of the exact diameter needed.

As a workaround, it is probably possible to attach an unmounted filter with epoxy or silicone at the front or rear of the adapter, and to find a filter sufficiently large for this while still small enough to sit within the front or rear bayonet. (If using silicone, keep in mind that it may be difficult or impossible to clean it off an optical surface, so the trick is not getting any silicone there in the first place. Easier said than done.)

I also assume that the purpose of the filter is to prevent dust contamination of the camera interior while doing photomacrography. One important thing to remember is that depth of focus (which is measured on the sensor side) is remarkably large in photomacrography. As depth of field (DOF, measured on the subject side) decreases with increasing magnification, depth of focus correspondingly increases. This means in practice that, in photomacrography, dust on a filter located a relatively short distance from the sensor will project a sharp shadow onto the latter. In practice, dust on the filter will have much the same effect as dust on the sensor - unless the filter is several cm from the sensor.

Some digital cameras do (or did) employ a permanent or removable filter in the camera body, mounted some distance from the sensor. I think the Nikon 1 was such an example. This was fine when using the camera for ordinary photography (large DOF and correspondingly small enough depth of focus to hide most dust particle on the filter), but not in photomacrography.

Another potential problem is that under certain conditions light can be reflected multiple times between sensor surface and a flat filter parallel to the sensor, producing image artifacts. A high-quality multicoated filter will be less likely to do this, but it may still happen.

Thanks for the reply :) You are correct about both assumptions.


The current filter is indeed some centimeters away from the sensor. I have not had any issues with dust or artefacts in my setup. In case the UV filter gets dirty: it is much easier to clean than the sensor itself and in case it would damage during cleaning: replacement is quick & easy and costs only a fraction of the price of a new sensor.


Which silicone would be best for glueing the glass to a plastic surface inside an adapter? Are you referring to the standard silicone used in bathrooms and that gives off acetic acid when it dries?

enricosavazzi
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Re: Preventing sensor dust

Post by enricosavazzi »

nielsgeode wrote:[...]Which silicone would be best for glueing the glass to a plastic surface inside an adapter? Are you referring to the standard silicone used in bathrooms and that gives off acetic acid when it dries?
I have used ordinary black bathroom silicone for several camera-related jobs, without apparent problems. It is of course better to leave it to harden in an aerated environment, so that the acetic acid fumes disperse. In the case of an adapter, just do the gluing and hardening with the adapter separated from the camera and other equipment.

Just to be safer, one can stay away from silicone that contains anti-mold chemicals. They are potentially volatile and may be released slowly, with unknown effects on camera equipment.

There are probably specific types of silicone for cementing optics (and I have seen examples of it in commercial optical equipment), but I have no information on where it could be obtained.
--ES

nielsgeode
Posts: 306
Joined: Tue Jul 31, 2012 11:47 am
Location: Groningen, Netherlands

Re: Preventing sensor dust

Post by nielsgeode »

enricosavazzi wrote:
nielsgeode wrote:[...]Which silicone would be best for glueing the glass to a plastic surface inside an adapter? Are you referring to the standard silicone used in bathrooms and that gives off acetic acid when it dries?
I have used ordinary black bathroom silicone for several camera-related jobs, without apparent problems. It is of course better to leave it to harden in an aerated environment, so that the acetic acid fumes disperse. In the case of an adapter, just do the gluing and hardening with the adapter separated from the camera and other equipment.

Just to be safer, one can stay away from silicone that contains anti-mold chemicals. They are potentially volatile and may be released slowly, with unknown effects on camera equipment.

There are probably specific types of silicone for cementing optics (and I have seen examples of it in commercial optical equipment), but I have no information on where it could be obtained.
Thanks a lot for the info. I am (maybe too) careful with these things and somehow I knew most silicone contains anti-mold stuff but didn't think of it until you mentioned it. For me that is enough to not use it, unless I have silicone specifically designed for optics.


I also sent you a PM

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