Has anyone tried adding a filter holder to lens adapters?

ProfHankD wrote:

Honestly, I haven't found filters all that useful with digital cameras except for special purposes. I suppose a polarizer might be worthwhile... but if the adapter is designed to have a filter with a specific optical thickness, you'd need one even for clear to keep the same rear focus distance, which would still degrade IQ a bit.

I do not see much use for them either but an ND and a polarizer is in the bag. The 58mm step up filter ring added to my 3D printer hoods is convenient for the 58mm caps and the use of the two 58mm filters that I have. Sure there is a risk that dirt on the filter shows faster when more extended from the front element but the depth of the hood for my lenses usually goes along with the focal length of the lens. I am measuring the hood depth all around more precisely now in manufacturing.

https://www.dpreview.com/forums/post/62095208

For the 75mm 5.6 scanner lens mounted into an M42 macro extension tube I made a hood that fits in the M42 thread at one side and a 58mm filter thread at the other side. A deeper hood I made for the 100mm scanner lens also mounted in an M42 macro extension tube. The M42 extension tube mounting makes it all quite universal when both side M42 threads, male/female, can be used.  For example in reversing the lens. The diameter of the lens barrel has to be small though. M52 extenders could be used for larger diameters.

75mm on the camera with short helicoid to MC-11 From front to rear; 58mm hood with male M42 rear fit in M42 extender tube with the barrel lens fitted in its center, M42 helicoid,  M42 to EOS adapter, MC-11 adapter. No chip added yet.

100mm on longer helicoid and its hood showing the rear side with the male M42 thread

100mm reversed mounted to the helicoid with a dual male M42 extender

Even projector lenses could be used in M42 female threads when an M42 thread on their barrels is made with a lathe. Studying that possibility; the standard 42 to 42.3 mm diameter lends itself quite good for that work, little to cut off for the thread and enough wall remains. For hoods a female M42 ring at the rear of the hood could be used.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

petrochemist wrote:

E Dinkla wrote:

ProfHankD wrote:

Honestly, I haven't found filters all that useful with digital cameras except for special purposes. I suppose a polarizer might be worthwhile... but if the adapter is designed to have a filter with a specific optical thickness, you'd need one even for clear to keep the same rear focus distance, which would still degrade IQ a bit.

I do not see much use for them either but an ND and a polarizer is in the bag. The 58mm step up filter ring added to my 3D printer hoods is convenient for the 58mm caps and the use of the two 58mm filters that I have. Sure there is a risk that dirt on the filter shows faster when more extended from the front element but the depth of the hood for my lenses usually goes along with the focal length of the lens. I am measuring the hood depth all around more precisely now in manufacturing.

https://www.dpreview.com/forums/post/62095208

For the 75mm 5.6 scanner lens mounted into an M42 macro extension tube I made a hood that fits in the M42 thread at one side and a 58mm filter thread at the other side. A deeper hood I made for the 100mm scanner lens also mounted in an M42 macro extension tube. The M42 extension tube mounting makes it all quite universal when both side M42 threads, male/female, can be used. For example in reversing the lens. The diameter of the lens barrel has to be small though. M52 extenders could be used for larger diameters.

100mm on longer helicoid and its hood showing the rear side with the male M42 thread

100mm reversed mounted to the helicoid with a dual male M42 extender

Even projector lenses could be used in M42 female threads when an M42 thread on their barrels is made with a lathe. Studying that possibility; the standard 42 to 42.3 mm diameter lends itself quite good for that work, little to cut off for the thread and enough wall remains. For hoods a female M42 ring at the rear of the hood could be used.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

I use a long m42-52mm helicoid for most of my projector lenses - it's much easier to stick a 52mm stepping ring to the outside of the lens body than cut a M42 thread. Only one of my projectors is too big for this & that's got a very long registration, so might be better connected via a lined drainpipe!

I've never tried reverse mounting my projectors, perhaps I should just stick filter rings to the front as well - not quite as neat as your adaptions admittedly.

Adding a very short M42 extension tube with the filter glued in behind helicoid and lens could be a solution for you. There are also the M42 to M39 adapter rings of about 4.5 mm thick that may fit somewhere between a male and female M42 connection. Filter glass disc of 38mm diam should fit with some glue into the 39mm female thread. Odd imperial pitch so unlikely a filter would fit that thread right away.

Aliexpress.com see M39-M42 Camera Lens Adapter Ring M39 Lens M42 Romp Ring M39-M42

For RF wide angle lenses that did not cope well with the FF sensors there has been some R&D done at the Fred Miranda forums. Most solutions had one extra element (dioptr filter) implanted at the front but I recall one at the rear of a lens too. So extra glass at the rear is not always becoming an issue.

I try to avoid huge lens constructions. Is the 52mm helicoid not much wider than the M42 one?  I understand the 52mm helicoid has a thread of 0.75mm pitch which is like filters can have so a stepping down ring from 52 to ? could do it.  What is the best size then at the 42<>42.3mm diam of slide projection lenses?

Reverse mounting of projector lenses is not delivering much I guess. Wide aperture is an advantage but the designs aimed at scaling beyond 1:10 and most have focal lengths that start above 60mm, you will need very long extensions to get to that scaling when reversed. Filter step up/down ring with the right diameter to glue on will not be that difficult to find. Male/male 52mm might be available too. I received a 58mm this week.

Met vriendelijke groet, Ernst
No photographer's gear list is complete without the printer mentioned !

petrochemist wrote:

I've recently seen several lens adapters with built in ND filters.

Potentially useful for lenses with odd size or no filter rings..

For most lenses I can't see any advantage in having them there rather than in front of the lens, but it's prompted the thought that it might be useful for IR shots etc to have the ability to fit a filter inside some of my adapters...

Has anyone tried this?

It wouldn't be difficult to machine an existing adapter to  accept a filter inside. Anyone with a lathe could do it. The problem would be finding a consistent size in filters to use.

BBbuilder467 wrote:

petrochemist wrote:

I've recently seen several lens adapters with built in ND filters.

Potentially useful for lenses with odd size or no filter rings..

For most lenses I can't see any advantage in having them there rather than in front of the lens,

Oh really? Try getting a filter for the front of a 800/5.6 Nikkor, then...

(yeah, I have one, it was quite expensive).

but it's prompted the thought that it might be useful for IR shots etc to have the ability to fit a filter inside some of my adapters...

Has anyone tried this?

It wouldn't be difficult to machine an existing adapter to accept a filter inside. Anyone with a lathe could do it. The problem would be finding a consistent size in filters to use.

No machining  necessary - 40.5 dia filters fit directly inside some EF-M4/3 adapters, for example. It is easiest to push a ring from a UV filter into the adapter, and then screw your filter onto that.

Useful for ND filters for video, and some other situations. Not so useful for PL filters, since it is harder to rotate them (get a Fotodiox filter for that).

Problem is remembering the filter is installed, and in which adapter

I see a few comments about "degrading IQ" and affecting focal length - both issues are overblown IME, Putting any filter on the front of a lens often reduces IQ in any case, particularly for telephoto use.

Seems reasonably likely that any adapter is being used with mirrorless, so any effect on focus is automatically corrected. No big deal.

petrochemist wrote:

I'm not sure if any of my many filters are 40.5mm ones, but this sort of approach sounds promising!

Perhaps I'll be able to get away with a 40.5-37mm step down - I have a fair range of 37mm filters. I'll move this up my list of projects

I think using a step down ring - probably larger than 40.5 - is a good approach. For adapters with a flat area the ring could be fixed with adhesive, double sided tape or sealant. Might even work if the right size for adapters that only have a tapered interior surface.

Problem is if you have fat fingers it is hard to get at the filter, and a PL might be impossible to remove.

And of course, there is no reason not to use a step up ring and mount the filter by the front thread, makes no difference in this situation.

I think it is a great idea, though it seems like it some of it would depend on the type of filter.  For example it seems certain filters like dichroic filters or dichroic polarizers even dispersion type filters, it would be better to have them on the front of the lens, because of the angle of incidence, and the fact that they are also mirrors that reflect light, which you probably don't want bouncing around.

SmoothOperator wrote:

I think it is a great idea, though it seems like it some of it would depend on the type of filter. For example it seems certain filters like dichroic filters or dichroic polarizers even dispersion type filters, it would be better to have them on the front of the lens, because of the angle of incidence, and the fact that they are also mirrors that reflect light, which you probably don't want bouncing around.

Also solar filters, you absolutely must have those on the front of the lens.

Since we're mainly adapting to mirroless cameras which focus from the sensor image focus shift should be accounted for and not be a problem - the one problem being if the shift prevented the lens reaching infinity focus.

Gato

Gato Amarillo wrote:

Since we're mainly adapting to mirroless cameras which focus from the sensor image focus shift should be accounted for and not be a problem - the one problem being if the shift prevented the lens reaching infinity focus.

Gato

The adapter should take that into account, drop-in filters in telephotos are included as part of the optical formula.

ProfHankD wrote:

SmoothOperator wrote:

Gato Amarillo wrote:

Since we're mainly adapting to mirroless cameras which focus from the sensor image focus shift should be accounted for and not be a problem - the one problem being if the shift prevented the lens reaching infinity focus.

Gato

The adapter should take that into account, drop-in filters in telephotos are included as part of the optical formula.

As I said in my post that started this sequence,

if the adapter is designed to have a filter with a specific optical thickness, you'd need one even for clear to keep the same rear focus distance, which would still degrade IQ a bit.

In practical terms, I've never noticed this with m4/3 - I have several long telephoto lenses (500 and 800) with rear filters, and all will achieve infinity focus with room to spare with and without out any filters on any adapter combination I've used.

ProfHankD wrote:

hindesite wrote:

ProfHankD wrote:

SmoothOperator wrote:

Gato Amarillo wrote:

Since we're mainly adapting to mirroless cameras which focus from the sensor image focus shift should be accounted for and not be a problem - the one problem being if the shift prevented the lens reaching infinity focus.

Gato

The adapter should take that into account, drop-in filters in telephotos are included as part of the optical formula.

As I said in my post that started this sequence,

if the adapter is designed to have a filter with a specific optical thickness, you'd need one even for clear to keep the same rear focus distance, which would still degrade IQ a bit.

In practical terms, I've never noticed this with m4/3 - I have several long telephoto lenses (500 and 800) with rear filters, and all will achieve infinity focus with room to spare with and without out any filters on any adapter combination I've used.

Assuming those lenses were not intended to take rear filters (or that you're comparing with/without a rear filter), that's because of two things:

These lenses were all intended to take rear filters (or placeholder/clear/UV).

1. The amount of movement needed to focus a long focal length lens is correspondingly larger, so 1mm doesn't move the focus point much. Infinity is also very far away, not just a few hundred feet, so make sure you're really checking infinity focus.

I think the moon is close enough to infinity for me.

1. Many long focal length lenses can focus past infinity to allow for thermal expansion of the barrel.

Yes, but at the end of the day, in practical terms, it just doesn't matter.