The D-Mount project

[Nathan Solomon]

This is the initial design, sent off now for SLA printing (high-res, tough-durable) to test the form and basic dimensions. In the image, I have it unscrewed to show the components, but essentially, I’m thinking the space between the D-mount lens base (screwed atop the red ring), and the bottom of the M12 blue ring is 10mm, with another 2.3mm from the bottom of that to the sensor. If anyone already knows that this will fail, feel free to tell me why. Otherwise 🤞🤞🤞

[Nathan Solomon]

I don't know if it's interest to anyone, but I took the information here as a starting point for exploring use of D-Mount lenses. I tried to document the process as well as I could, so it's probably pretty boring to anyone not specifically interested. I hope it's of use to those who are. By the end of the month I should be done with the building, and probably have two more posts yet to write to cover the completion. http://coldmaceration.com/camera-conversion-project/

[andrgl]

@Nathan Solomon Please keep us up-to-date, I am personally enjoying following this project and am interested in pursuing doing something similar. 🙂 Everything you share is a great help.

[kye]

Well, I think that the D-Mount project might be dead, at least for me.

Some time ago I ordered a genuine SJ4000 action camera, as they're structured very differently internally and are much more supportive of lens changes.  Here it is, front plate and front panel removed (which is very easy to do) and lens removed (just twist with a strong pair of pliers to break the glue and it unscrews easily)...

and here it is with the mighty Cine Nikkor just sitting on top:

You can probably already see what the problem is - it interferes massively with the battery slot.

What you can't see from those pictures is that when the lens is mounted at this distance from the sensor and is set to focus to infinity it can barely focus beyond the hand that is holding the lens.  The infinity focus is so bad that focusing close-up on the lens is basically the same.  The Nikkor would need to be mounted a significant distance further into the camera, making its intersection with the battery a problem.

However, I also bought two other M12 lenses when I bought the camera...  Here is the 8mm one, which gives a FOV somewhere around the 40-80mm range (I haven't really tried to estimate it better than that) which is perfectly serviceable and does the job of not being a crazy fisheye lens like the stock one.

Here it is mounted in the camera:

The other idea of the lens replacement was that it would be less sharp and slightly "vintage" with it's 2MP CCTV "pedigree".

So, how does the footage look?

Well, it's one of those good/news bad news things.

Good news is the lens is great and flares like a monster:

The good news / bad news part is that the new lens doesn't appear to have an IR filter on it, and I didn't swap the one from the other lens over yet, so it's an IR camera!!

I've always wanted to try IR photography so that's pretty cool.  Also, my original plan was to make everything B&W anyway, so that doesn't really matter much, and actually gives more light to work with, which is great for these tiny sensors.

This pot is bright red, just like the leaves of that plant are bright green:

The bad news is that the compression is pretty crunchy:

Of course, I've worked with worse, so that's fine.

But, going back to the Cine Nikkor, unless I want to somehow move the battery connectors, which are soldered onto the circuitboard IIRC, then the lens isn't going to be mounted to this camera any time soon.  I'm also wondering if the codec is good enough to really warrant putting a nicer lens on it.  

I also bought a 16mm CCTV lens, but that can't even mount because it has to be so far AWAY from the sensor that it doesn't even touch the M12 mount, I'm free-lensing it at a decent distance in front of the camera.  

Also, the FOV from the 13mm Cine Nikkor would be prohibitively long, unless shooting with a tripod or a rig that's at least 20 times the size of the camera.  One of the benefits of this setup is that it's so small I can film with it without any other rigging.

I shot a project the other day with just my phone in 240fps mode, and am having fun editing that (my wife picked a ridiculous song for the edit which really elevates the project lol) and I'm wondering if using my phone is the ultimate camera for street and casual videography.  Everyone takes photos these days and if I pull a face while I'm shooting maybe people will just assume I'm taking a selfie and not react in that "I've just been photographed!!!!" kind of way that some people do.

So, SJ4000 and 8mm 2MP CCTV lens..  is it a cinematic beast?  Probably not, but is it an interesting thing?  Sure...

It's probably the Super-8 version of an action camera.

[QuickHitRecord]

This is super intriguing and it's great to know about this inexpensive action cam for lens experiments. Thanks for sharing the detailed notes. Hope we can see some video soon.

[kye]

On 1/26/2021 at 12:57 PM, QuickHitRecord said:

This is super intriguing and it's great to know about this inexpensive action cam for lens experiments. Thanks for sharing the detailed notes. Hope we can see some video soon.

I'm planning on shooting some stuff soon.  I may even make the project B&W - here's that last still with a straight B&W conversion (and none of the other grading I would also do to it):

The modding process was super-easy, so if anyone is curious then I'd recommend trying it.  The only thing to watch is that you get a genuine SJ4000 as there are heaps of fakes on Ebay.  I previously bought the cheapest one I could find, for the cheap camera challenge, and it was definitely a fake and the 640x480 video it captured was truly truly awful.  There are a few easily google-able sites about how to spot a fake from the genuine one so it's not that hard.

[kye]

As promised...

Shot on the mighty SJ4000 with replacement 8mm M12 lens.  I brought the footage into Resolve and pounded it with a hammer until it no longer looked like a cheap modern camera, but reminded me of an expensive older camera.

I might have been a little heavy-handed with the film-grain though, I thought YT would compress it slightly more, anyway, enjoy.

[kye]

Another vignette..  

I'm now officially over the IR sensitivity.  It makes people look, well, awful.  I'm also a bit over the focal length being a bit too long for some situations.

Lucky, I have IR Cut filters on order, and I say filters, because I'll need one for this lens and one for the new lens I have on order, a 2.8-12mm zoom lens.  This will give around 20-85mm equivalent FOV, and (I think) has a focus control, so I might be able to focus closer too, so that will be fun.

I also found the quality setting on the camera was not set optimally, so did a modes test and found the best looking settings, and also optimised a grade and saved it as a Powergrade in Resolve, so now I can just apply it whenever I want and save time pixel-peeping in post.

Here's the modes from the camera:

and here's the powergrade applied, with each shot having the edge softening optimised to cancel out the halo from the sharpening and compression applied:

The middle one looks best, so that's what I'll go with.  

The goal of this project was to get me shooting and doing smaller projects and it certainly has done that, so that's a success in my book.

[kye]

An update...

My 2.8-12mm zoom lens arrived and I've completed the mods.  It's a nail-biting tale of daring and disaster, but as sure as Hollywood using action cameras with zoom lenses, has a happy ending nonetheless.

First impression was that the envelope with the single layer of bubble wrap that was protecting the lens had lost its air long ago, probably while still in mainland China, but concerns of damage were quickly alleviated when I discovered this this is a beast, is heavy, and is made completely of metal.

It's also somewhat larger than I anticipated..  here it is next to the camera and existing 8mm lens:

I put it onto the camera and couldn't get focus, even if I screwed it all the way in.

Naturally, my first impression was to take the camera apart, and modify it to get infinity focus, however it later turned out that this was wrong, and that I had screwed the lens into the camera too far, but back to me going down the wrong path...

Camera in pieces:

The bit I chopped off thinking it was the only barrier between me and cinematic goodness:

It was around this time I realised my error, and that the lens got good focus (across the whole zoom range) with only 2 turns of the lens into the mount.  

This meant that clearance between the rear element and the sensor wasn't in danger, so I installed the IR Cut filter onto the rear element of the lens.  Luckily this lens had a flat rear-element, which made getting the IR filter also flat quite a straight-forward process.  I found success with the previous lens by using PVA woodworking glue, which dries clear and holds the IR filter securely (which I accidentally tested by dropping that lens ~1m onto a tiled floor and it stayed on just fine!), so here's the filter:

I applied the PVA with a pin and I find that if you give yourself a big lump of glue then you can tell how quickly the glue dries by watching your lump dry, which isn't required in this case but is useful if you glue somewhere that you can't see:

Next job was to modify the front plate to allow the lens to sit where it needs to.  In this case the front part that clips in needs to be removed:

It comes out easily and looks like this when mounted back on the camera:

You can see that the mount in the camera is only plastic, which is quite concerning for robustness, but it also presents another problem, which is that the focus and zoom controls on the lens are stiff in parts of their range, and the lens would rather twist in the mount rather than adjust, so my previous trick of putting plumbers tape into the threads did nothing.

This is where the story takes a turn - I decided to glue the lens into the mount.

I did this for a few reasons.  Firstly, this lens give the focal range I need and so I wouldn't need to change it ever again.  Secondly, it will help resist turning in the mount, and will also make the whole thing more robust.

In terms of risks, I figured that if I needed to remove the lens for some reason I could potentially break the seal on the glue and get it out.  If that didn't work then I might break the lens thread in the camera, but maybe not enough to prevent other lenses being used that go deeper into the camera (the previous 8mm lens I had in there went in quite a way).  There was never going to be damage to the new lens as it's all metal, including the mounting threads.
Worst-case is I kill the SJ4000, which was under $100, and could be replaced.

So, I went for broke, and put in quite a lot of glue, both onto the lens and the mount.  I made sure to dry it lens-down so that any squeeze-out would drop down the outside of the lens rather than on the inside of the lens mount and potentially onto the sensor.

I waited until my lump of glue was completely dry, and then put a battery in and fired up the camera.

Disaster.

You will note that the windowsill is in focus, so the diffusion is not from poor focus.  I suspected some kind of haze from the glue, considering it was fine with the lens installed prior to my glue-up.

I have a theory about haze.  If something can become a gas and then solidify onto a surface, then it must be able to become a gas again and everything that condensed should evaporate again leaving a clean surface.  Assuming that it doesn't perform a chemical reaction or anything.  I thought that PVA is water-soluble, so I figured that the haze could simply be condensation, considering that the little chamber between the lens and sensor would have been where a lot of the water would have gone.  

First attempt to cure it was the late afternoon sun:

I pulled the battery and SD card after taking this shot, to remove power and the possibility of them being damaged, and to also let more air in and out via those openings in the case.

After sunset I fired it up again and the haze had turned into evenly spaced strange little globs, maybe 10 across the width of the sensor.  I didn't get a photo of that, but I thought that movement was good, showing that whatever it is isn't stuck there forever.  I left it there overnight and thought I'd contemplate the next strategy the next day.

The next morning.....  BINGO!

Like a phoenix rising from the ashes!  I suspect dry air from the air-conditioning gave it the time required to dry out.

So, having flirted with disaster but avoiding peril with great skill luck, what do we now have?

FOV at wide end:

FOV at long end:

iPhone 8 FOV:

My completely non-scientific analysis suggests that it's about equivalent to an 18-60 lens, and the f1.4 aperture should mean that exposures are good until the light gets low, which is good because the sensor is likely to have poor ISO performance.

So, how is it to use?

Well, if there was a competition for least par focal lens in the world, this would be my nomination.  Each end of the zoom range has its infinity focus setting at each end of the focus range, and if you go from being in focus at one end of the zoom range and take the zoom adjustment to the other end then the bokeh balls are 1/6th the width of the frame (I did measure that) so it's not a subtle effect.  I checked if the zoom and focus rings should be locked together but they deviate slightly over their range.

The locking pins are useful for controlling the zoom and focus, but if you screw them in completely then they lock the controls, so I'm thinking that I should glue them in place so they're solid.  I'll have to be careful not to get glue into the mechanisms but that shouldn't be too hard.

So, how the @#&@#$ do you focus using the 2" 960x240 LCD screen?  Why, by using the up and down buttons on the side to engage the 4x digital zoom function of course!

In terms of natural diffusion and flares, the lens also looks promising, and I've already noticed a round halo if you put a bright light in the centre of frame, so that should be fun to play with.  There's probably little chance of this lens ending up in the clinical lens thread!
I've matched the colours to the BMMCC via the test chart, so already have a nice post-workflow for it too.

I haven't shot anything with it, but will do soon, and considering its size it should be quite easy to film in public without drawing too much attention.

So, is it a pocket cinematic beast?  Only time will tell.

 

[leslie]

nice work persevering @kye, I kinda lent the other way. Lashed out on the gopro 9 yesterday. I figure its a decent upgrade over the 6 i have. I have some plans for it, not as extreme as yours however. i'll post something later 

[kye]

4 hours ago, leslie said:

nice work persevering @kye, I kinda lent the other way. Lashed out on the gopro 9 yesterday. I figure its a decent upgrade over the 6 i have. I have some plans for it, not as extreme as yours however. i'll post something later 

Thanks.

I'm not sure how brave I'd be with a newer and more expensive action camera..  the fact this would be cheap to replace is what makes me feel ok to take these risks.

[kye]

I went out and shot with it and missed focus on quite a few shots.  The 4X digital zoom is ok for focusing, but the controls are a bit stiff in places and it's quite sensitive.

I'm thinking I'll have to fabricate some a much longer pin / arm for the focus control to give me more leverage and fine control.  Definitely more to come.

[QuickHitRecord]

A great read, Kye. Way to roll with the punches. It's neat to have what is probably the only instance of this lens in use with this camera in the world. I look forward to seeing your footage with this setup.

[kye]

First colour video from the SJ4000 / zoom lens combo....

I pushed the colour, both towards warm/magenta and also in saturation, partly to experiment with a punchier look, but also to see how far I could push the image.

This is the final look I applied:

and this was the untouched SOOC footage:

Not a bad look, but not the one I was going for.  Sunsets aren't green, after all!

The only mod that I still want to make is to extend the lever on the focus ring to give finer control and more leverage (as some parts of the focal range get a bit stiff).  It's quite difficult to focus, even with the 4X digital zoom that can be used to 'punch-in' before shooting, and I missed quite a few shots while filming this.

Overall though, it's quite a capable package.

 

[PannySVHS]

@kye Masterpiece. It would have been worth to use a tripod to compliment your beautiful framing and montage. Love the shotdesign and realization and the juxtaposition of images and montage in its entity. cheers

[kye]

12 hours ago, PannySVHS said:

@kye Masterpiece. It would have been worth to use a tripod to compliment your beautiful framing and montage. Love the shotdesign and realization and the juxtaposition of images and montage in its entity. cheers

Thanks!

Those shots are the more formal shots from the real video is much more casual thing, including things like my wife throwing seaweed at me, and other amusements that I'm not allowed to post publicly.. In that context those shots are quite stable!

Compared to the action camera, a tripod would literally make the rig hundreds of times larger, and really defeat the "action" part of it 🙂 

[PannySVHS]

seaweed and a tiny, stable minitripod would be ultimate naughtyness and viewing pleasure. 🙂 Seriously, do the tripod thing. Some of the shots would have been elevated for great to magnificient! Even moreso with the montage, which is very tight. Would love to see some c- or d-mount magic with your BMMCC.

One side note, I have a couple Zeiss Tevidon laying around, many single ones and one complete as brand new set, except the 100mm and the 18-90 zoom. But have not brought myselt to order that darn Tevidon to C-mount adapter. So, always grateful to see what lens projects you guys got going on.:) cheers

[kye]

5 hours ago, PannySVHS said:

seaweed and a tiny, stable minitripod would be ultimate naughtyness and viewing pleasure. 🙂 Seriously, do the tripod thing. Some of the shots would have been elevated for great to magnificient! Even moreso with the montage, which is very tight. Would love to see some c- or d-mount magic with your BMMCC.

One side note, I have a couple Zeiss Tevidon laying around, many single ones and one complete as brand new set, except the 100mm and the 18-90 zoom. But have not brought myselt to order that darn Tevidon to C-mount adapter. So, always grateful to see what lens projects you guys got going on.:) cheers

I have a similar project that I shot with the BMMCC and the Cosmicar 12.5/1.9 C-mount and the Voigtlander 42.5/0.95 so I'll have to do the same re-cut process to remove all shots that don't include a model release!

I also have an OG BMPCC on its way to me, so am planning on lots more outings with it, likely with the 7.5/2 and 14/2.5, but also perhaps with the 14-42 or 12-32 kit lenses, which have OIS, so should be much more stable 🙂 

[megavolt]

Allow me to add a bit info to this lovely D-mount project.

 

https://blog.monouri.net/archives/ipnonekaihatu.html