Filter Device between Lens and Body

I found this:

https://www.bhphotovid​eo.com …filter_mount_ad​apter.html

Even way before I knew of the adapter I linked to, I have been thinking for some time how nice it would be to have such a device, not as a lens adapter, but as a behind the lens filter adapter.

I have seen a few lens that incorporated the principle within the lens; it would be especially beneficial for long lens that are notorious for not tolerating filters mounted normally.

Does anyone make such a device to fit normal EOS EF/EF-S cameras/lens ?

You can't use any such a device behind an EF lens mounted to an EF camera unless you want the effect of an extension tube.
The lens needs to be 44mm from the sensor. You can't just move it further away. Well, you can, but you now have an extension tube.
On a wide angle lens only a small distance increase means you can now only focus on subjects inside the lens which is not particularly useful.
On a longer lens you not only lose infinity focus, maximum focus distance can be drastically reduced.

Choderboy wrote in post #19297321
You can't use any such a device behind an EF lens mounted to an EF camera unless you want the effect of an extension tube.
The lens needs to be 44mm from the sensor. You can't just move it further away. Well, you can, but you now have an extension tube.
On a wide angle lens only a small distance increase means you can now only focus on subjects inside the lens which is not particularly useful.
On a longer lens you not only lose infinity focus, maximum focus distance can be drastically reduced.

Thanks for the explanation.

Why can such a device work to adapt between camera and lens brands/styles; would it not also have the extension tube effect ?

BuckSkin wrote in post #19297502
Thanks for the explanation.

Why can such a device work to adapt between camera and lens brands/styles; would it not also have the extension tube effect ?

The adapter you linked to is for dissimilar mount types - for EF lenses to RF bodies. EF lenses expect a flange distance of 44 mm. For RF lenses it is only 20 mm. So if you are mounting an EF lens to an RF body, for it to work normally, you need an extra 22 mm between lens and body. That can be provided by an adapter such as in your link, or by several other types of adapter with or without filter holders.

Just looking at the accessories I gotta wonder. Why on earth would you want a clear drop in filter?

gjl711 wrote in post #19297511
Just looking at the accessories I gotta wonder. Why on earth would you want a clear drop in filter?

It seems to function as a very expensive cover for the filter slot.

There might be some situations where it is important to maintain an exact effective optical path length...

Archibald wrote in post #19297517
It seems to function as a very expensive cover for the filter slot.

There might be some situations where it is important to maintain an exact effective optical path length...

I understand that the optical path length needs to stay the same and that's what the filter holder body does. I also understand the need to a cover when no filter is required but to sell a clear glass filter for $127 when a simple plastic cover would do the same seems like needless gouging.

gjl711 wrote in post #19297520
I understand that the optical path length needs to stay the same and that's what the filter holder body does. I also understand the need to a cover when no filter is required but to sell a clear glass filter for $127 when a simple plastic cover would do the same seems like needless gouging.

Sure, agreed about the price. Re the optical path length, filters change that slightly because of their refractive index, so in critical applications, you would need to put a piece of glass in there with the appropriate optical path length to keep it the same.

Archibald wrote in post #19297555
Sure, agreed about the price. Re the optical path length, filters change that slightly because of their refractive index, so in critical applications, you would need to put a piece of glass in there with the appropriate optical path length to keep it the same.

Sounds like a stretch. Do you work for Canon by chance?

Archibald wrote in post #19297504
The adapter you linked to is for dissimilar mount types - for EF lenses to RF bodies. EF lenses expect a flange distance of 44 mm. For RF lenses it is only 20 mm. So if you are mounting an EF lens to an RF body, for it to work normally, you need an extra 22 mm between lens and body. That can be provided by an adapter such as in your link, or by several other types of adapter with or without filter holders.

So, in accordance of preserving this flange distance, certain lens mount styles can be adapted to certain cameras, but not the other way around.

If I can effectively put lens mount A on camera body X via an adapter and it work as desired, then a lens meant to fit camera X cannot be adapted to camera A due to the tube effect, right ?

This lens distance is something all new to me.

gjl711 wrote in post #19297563
Sounds like a stretch. Do you work for Canon by chance?

As an example, if the filter glass is 3 mm thick, that shortens the optical path by about 1 mm. Does that sound like a stretch to you?

BuckSkin wrote in post #19297583
So, in accordance of preserving this flange distance, certain lens mount styles can be adapted to certain cameras, but not the other way around.

If I can effectively put lens mount A on camera body X via an adapter and it work as desired, then a lens meant to fit camera X cannot be adapted to camera A due to the tube effect, right ?

This lens distance is something all new to me.

You can put EF lenses on RF cameras (with an adapter), but putting RF lenses on EF bodies won't work. That's why some are not buying the new RF 100-500mm lens. It fits on their R cameras but they might still have an EF body around and it won't go on those.

Archibald wrote in post #19297555
Sure, agreed about the price. Re the optical path length, filters change that slightly because of their refractive index, so in critical applications, you would need to put a piece of glass in there with the appropriate optical path length to keep it the same.

gjl711 wrote in post #19297563
Sounds like a stretch. Do you work for Canon by chance?

Archibald is correct, although my experience is with microscopes. The absence of that thin coverslip can introduce chromatic aberration.
https://www.microscopy​u.com …sics/coverslip-correction

Archibald wrote in post #19297599
You can put EF lenses on RF cameras (with an adapter), but putting RF lenses on EF bodies won't work. That's why some are not buying the new RF 100-500mm lens. It fits on their R cameras but they might still have an EF body around and it won't go on those.

Thanks.

Given the evidence, if one had an RF camera, one would be well advised to put their money in the adapter and a long EF lens rather than the long RF lens; and thus, have more options in both resale and usability; at least that is my take.

BuckSkin wrote in post #19297688
Thanks.

Given the evidence, if one had an RF camera, one would be well advised to put their money in the adapter and a long EF lens rather than the long RF lens; and thus, have more options in both resale and usability; at least that is my take.

Yes, if the RF and EF offerings are equal. But Canon has sweetened the RF lenses, making each a little better in certain ways than the corresponding EF lenses. So if you are committed to mirrorless, you want the RF lenses - until you see the price tags.