Adapters to put the UV filter behind the lens

[rfcurry]

I have been 3d-printing some adapters that permit me to install one of my UV bandpass filters on the M4/3 camera side of my Exakta and M42 lenses. I have often wished to get the filter behind the lens for macro shots and now I can.

 

I am thinking about offering such adapters as an inexpensive accessory to any UV-bandpass filter sales. So, I am taking a poll to determine which mount adapters are most popular with UV photographers. So far, I have Exakta and M42 in and M4/3 out. What are the IN/OUT combinations that you use? (Obviously, this would only apply to those cases with a large difference between the FFD of the lens and the FFD of the camera.)

I'm looking forward to your input.

 

Thanks.

[lukaszgryglicki]

I *think* Nikon-F is also popular... especially because of UV-Nikkor?

 

[ulf]

I would not dare to let an expensive lens like the UV-Nikkor hang in a 3d-printed plastic adapter!!

 

3D-printed parts are far from as strong as aluminium parts.

Extrusion printed plastic parts have less strength between the layers (Z-axis) than than in X- and Y-direction.

 

Then it would be safer to print an adapter to hold a filter inside some cheap generic lens to camera-adapter.

[aphalo]

I agree with Ulf that I would not use any 3D printed adapter made from the usual filaments or resins except with very cheap and light-weight lenses. On the other hand, commercial 3D printing with composite materails may be strong enough, but not cheap. I have yet to order anything from Weerg, but they do offer 3D printing with materials that I think could do a good job. For example carbon/fibre reinforced nylon (https://www.weerg.com/en/global/materials-and-finishes/3d-printing/nylon/nylon-pa12-carbon-fiber). They also do metal parts by CNC machining. https://www.weerg.com/ There are surely other suppliers elsewhere providing similar services.

 

I am using the DEO & Optolong OWL EF/MFT adapter with filter drawers, even tough I do not have any Canon EF lenses. I had to have it machined to fit the OM-D camera as it is a bit oversized on the outside and unmodified it hits the "false-pentaprism" protrusion of the OM-D cameras. I add M42/EF, OM/EF and Nikon G/EF adapters when needed. Works quite well but the filter drawers are available only in 48mm and 52mm and rather expensive when not on sale. So, as to the original question, an EF/MFT adapter with a filter holder would be the most versatile and easily adaptable to other mounts with slightly longer FFD like M42 and Nikon. EF adapters for M42, OM and Nikon F are compact enough and cheap enough that I keep them permanently on the M42, OM and Nikon lenses that I use most frequently. When needed I adjust the FF distance with permanently installed shims. By the way, the FFD of my OWL adapter is spot on. Some time ago wrote about the OWL adapter at https://www.photo-spectrum.info/2020/06/a-lens-adapter-with-a-filter-drawer/.

[rfcurry]

ulf,

 

I'm sure that some 3d-printed parts are fragile. However, if the infill density, infill pattern, layer speed, layer thickness, EO temperature, build plate temperature, wall thickness, and a dozen other parameters are chosen for strength, and the filament is a good quality PETG or even carbon-fibre-filled Nylon; then the resulting part can be remarkably robust. Some have used 3D-printed gears for two years in demanding applications, without failure.

 

I agree with your statement "I would not dare to let an expensive lens like the UV-Nikkor hang in a 3d-printed plastic adapter!!" but I would expand it to say, "I would not trust myself with a $30,000 lens." I know I have a poor sense of balance and knock things over constantly. Watching my tripod crash to the ground with such a valuable lens is something I would not risk. :) 

I have a tension test stand, good to, iirc, 2200 newtons. Maybe I should dust that off? I could torque the adapter to point of failure.

 

Ulf,

What parameters and materials do you use with your 3D printer that discouraged you from using it with camera adapters?

 

Thanks.

 

 

[rfcurry]

Pedro,

 

Thank you. That is the sort of info I was hoping for. btw, I am fascinated by the work you are doing with UV4Plants. 

So, I will look at building an EF/MFT adapter, perhaps with a slide-in filter holder. That might be an interesting design/coding challenge.

 

Regards,

Reed

[ulf]

2 hours ago, rfcurry said:

ulf,

 

I'm sure that some 3d-printed parts are fragile. However, if the infill density, infill pattern, layer speed, layer thickness, EO temperature, build plate temperature, wall thickness, and a dozen other parameters are chosen for strength, and the filament is a good quality PETG or even carbon-fibre-filled Nylon; then the resulting part can be remarkably robust. Some have used 3D-printed gears for two years in demanding applications, without failure.

 

I agree with your statement "I would not dare to let an expensive lens like the UV-Nikkor hang in a 3d-printed plastic adapter!!" but I would expand it to say, "I would not trust myself with a $30,000 lens." I know I have a poor sense of balance and knock things over constantly. Watching my tripod crash to the ground with such a valuable lens is something I would not risk. :) 

I have a tension test stand, good to, iirc, 2200 newtons. Maybe I should dust that off? I could torque the adapter to point of failure.

 

Ulf,

What parameters and materials do you use with your 3D printer that discouraged you from using it with camera adapters?

 

Thanks.

 

 

Mostly ABS, for it's higher temperature stability.

I do not remember details of printing settings as it was quite a long time ago. 

I guess the technology has improved with new materials and refined printers.

 

I moved to printing with a resin printer that has higher precision and a homogenous structure.

Some of the resins are rater tough, but If I would make a filter holder -camera-lens adapter I would still use a hybrid structure with the ends mating camera and lens made of metal.

A full plastic structure would IMHO not handle wear and tear good enough. For a temporary solution for a quick test maybe.

 

The problem with mechanical strength due to the layer structures, almost like in wood is well known.

When I designed holders/hangers for my filter magazines There was a lot of problem with breakage in the beginning.

[KaJashey]

I have the DEO-tech OWL Nikon F to Sony E adapter with filters behind so I'm already satisfied. Some people trying to use wide angle lenses on this adapter are not satisfied. There can be edge corner blurriness because of focusing issues with the filter behind.

 

Before I bought the adapter I thought about designing and 3D printing such an adapter. 

 

I like that the nikons aperture can usually be controlled mechanically. It might be hard though not impossible to 3d print the control for that. I had an idea with print in place gears... probably was best as an idea because print in place gears can be stiff/unsmooth

 

When I looked into making an adapter with a filter in back the optics say you need to tweak the flange distance just i little bit to keep the same focus range. For F to E it was 0.6mm longer - I believe -I'm a little fuzzy on the direction. You might want to work that out independantly. It depended on the filter thickness so that was an average I came up with from a very small sample.

 

As a 3d print enthusiast I feel the body of the print would usually be secure enough but I would worry about details of the connector coming loose. If I had a Nikon UV macro I would look at least 3 times at the adapter and especially the small parts of the connector.

[LookCloser]

On 12/12/2022 at 1:45 AM, rfcurry said:

I have been 3d-printing some adapters that permit me to install one of my UV bandpass filters on the M4/3 camera side of my Exakta and M42 lenses. I have often wished to get the filter behind the lens for macro shots and now I can.

 

I am thinking about offering such adapters as an inexpensive accessory to any UV-bandpass filter sales. So, I am taking a poll to determine which mount adapters are most popular with UV photographers. So far, I have Exakta and M42 in and M4/3 out. What are the IN/OUT combinations that you use? (Obviously, this would only apply to those cases with a large difference between the FFD of the lens and the FFD of the camera.)

I'm looking forward to your input.

 

Thanks.

I love the idea, but is it not just as easy to have a set of screw adapters behind the m42 thread to house your screw thread filter.
M42Lens ->42mm to 52mm adapter -> 52mm UV bandpass filter -> 52mm to 42mm adapter -> M42 to M4/3 adapter or focus helicoid.

Exactly like I have in this setup

 

I have thought about installing a clip in style filter inside the helicoid, but the arrangement in the image below takes care of any light leaks very nicely.

 

[colinbm]

I use a M42 x 1mm pitch,  adjustable aperture behind the lens to eliminate bad reflections from inside too.

[Lou Jost]

Don't forget that for fast lenses (faster than about f/2 to f/2.8) you can't add filters to the back without introducing optical aberrations. When focused at infinity, you can add even thick filters in front of the lens without causing aberrations.

[ulf]

Rear filters also harm performance for some good lenses optimised for film.

That is the same phenomenon that gives problems when changing from film to unmodified digital cameras with thick internal BG and anti-aliasing structures. Some Leica M lenses have that problem making some vis cameras less suitable. 

 

I was surprised that my Irix 15mm worked as well as it did with a rear-mounted 2mm 850nm filter, but that might have been close to the thickness of the now removed BG and dust-shaker filter. Naturally the filter made the focusing scale completely wrong as the camera is recalibrated to work without ant rear extra glass or filter.