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See the link in the first post above :

For a description of the optics, go to:  https://www.magiclantern.fm/forum/index.php?topic=9741.msg242199#msg242199

Nice!

Only one problem: I don't have a 5K monitor... 

Mine is not necessarily a macro probe. I can adjust the focus from lens surface to infinity, and I can also exchange the 1.7 mm fisheye lens to a rectilinear 4.35 mm one, the angle of which is similar to a 30-40 mm EOS-M lens.

Here is a photo of the finally assembled lens:



I had to make three threaded tubes in order to be able to position the relay lenses individually... The brass hexagonal "nut" at the left end is the focus, the O-ring gives a bit of friction so it doesn't move unintentionally.

Next part of the project: a prism to enable shooting horizontal views with the camera pointing down...

It is great! Is there some "aliexpress" alternative?

Sure - but it's "only" US$ 2,299.00 :

https://www.venuslens.net/product/laowa-24mm-t14-2x-periprobe/

Look for "periscope lens"... well, strike that, I searched myself and found only trash...

First test of the above mentioned "periscope lens" installed in aluminum tubes is now on "Share your videos", i.e. here:

https://www.magiclantern.fm/forum/index.php?topic=26804

Here's the very first test of my "homebrew" 1.7 mm Periscope lens, with the optical elements installed in a 3-part aluminum tube with threaded joins:

https://youtu.be/8tTAG7qLysQ

For a description of the optics, go to:  https://www.magiclantern.fm/forum/index.php?topic=9741.msg242199#msg242199

Still some adjustments to be made to the tubes, improving focusing (now push-pull, will be threaded), reducing the vignetting, etc...

This was shot with an EOS M, at f8, 400 ISO, h264 with ML's 3x zoom.

Interesting... I don't really know anything about optics, but is there any glass types (or maybe crystal) that can achieve the same effect with less thickness so it can fit?

Maybe - but most glasses have pretty much the same refractive index (around 1.5-1.7). Maybe it could be done with a block of diamond (index 2.4)?  Have you got a spare piece to lend me?

3-CCD video cameras do not have a shutter, so the space between lens and sensor(s) is almost totally filled with glass. That's not possible on the EOS M, where you can't get closer than about 5 mm to the sensor.

(In fact, in many 3-CCD cameras, the sensors are "glued" directly to the prism... as seen here: https://en.wikipedia.org/wiki/File:A_3CCD_imaging_block.jpg - that looks just as "scientific" as my own hot-glued block, right? )

You can actually consider the 40 mm block of prism-glass as an optical element of the lens itself. Without that element, the aberrations appear. Being able to insert 35 mm of glass removed a lot of the problems, but not at full aperture. (I painted the f-numbers 1.4 to 2.8 red on the aperture ring...  )

For a description of such a prism, see: https://en.wikipedia.org/wiki/Dichroic_prism

Here's the very first movie test on the "optical bench" - mid-take, I'm actually almost touching the lens with my finger:

https://youtu.be/1Vud91Klwys

When I think about lens construction and manipulation I think about millimetric laser-size precision, and then you mount all that with some weird shaped crystals and some glue and it works perfectly fine 

Well, the only important dimension is actually the parallelism of the glass block, and that was simple, just a flat surface! The back-focus adjustment on the lens itself took care of the rest... The tube is made on my lathe, which ensures that front & back are parallel, too.

(Yea, I have had to do very exact "shaving" on some other C-mount lenses to get them to focus properly... e.g. a Canon 12.5-75 mm f 1.8 lens - in fact, the last adjustment was with a layer of magic scotch tape between lens and mount!)

cool, show us how it looks at 1.4! I think some rainbow effects are nice in certain situations

Here's the same subject as above, first shot at f 1.4, then stopped down to f 4.

https://www.youtube.com/watch?v=KJRGMwC3LOg

As you clearly can se, it's no-go at f 1.4 !

But with 5 mm more glass, it certainly would be a lot better at f 1.4 - a pity such a clump wouldn't fit between lens and shutter...

Very interesting. Do you have any images of the lens and how the glass was put in? Any before after the fix recordings?

The lens:



The two prisms can be 45-90-45 degree prisms, as seen here: https://en.wikipedia.org/wiki/Porro_prism

or, they can be of this, slightly narrower type:



Both types of prisms are found in binoculars, the narrower ones in "straight tubes".

The important thing is that they need to be attached with UV-curing glass-glue, so that the opposing sides are exactly parallel. Then the two prisms will behave as a single piece of glass. The nice thing is that the actual thickness can be adjusted by "sliding" along the long edges.

Here is a photo of how I mounted the 35 mm thick block inside a mount tube I turned on the lathe:



In fact, the block is attached inside the tube merely with hot glue! Placement is exact, since when gluing, I placed the EOS mount ring and the glass block on a flat surface = automatic parallelism! The other end of the tube is screwed to the back of the zoom lens which has a "back focus adjust" knob - quite necessary, otherwise I would have had to make the adapter tube to 0.01 mm tolerance... possible, but needing a lot of trial and error to get right!

Unfortunately, I didn't save any "before" videos, they were so dismal!

But here is a jazz concert, shot three years ago with the then already prism-modified 7.5-97.5 mm zoom lens plus ML 3x (the closeups), as well as the Canon EF-M 11-22 mm and 15-45 mm (wide shots), altogether 3 cameras (synced with an electronic clapperboard shown further below) - all set around f 5.6 - 8:

https://www.youtube.com/watch?v=a6xn-oLqTJQ

You can clearly see that the closeups aren't as sharp as the wide takes.

Home-made electronic clapperboard:

https://www.youtube.com/watch?v=-ozxsKgLSVA

You can buy one - it's "only" US$ 2,299.00 :

https://www.venuslens.net/product/laowa-24mm-t14-2x-periprobe/

Mine will not be as good, but a few f-stops faster, and much wider...  ... and cost me zilch!

I have another optical project ongoing, too, a relay-lens system for a "periscope lens" using a 1.7 mm fisheye lens for GoPro-type cameras. Here, too, ML's 3x function enables full-frame video from that tiny lens.

However, it necessitates quite an optical construction, here assembled on a piece of angle iron, working as an "optical bench":





Explanation: Furthest from the camera, at left, is the 1.7 mm fisheye lens, diameter only 22 mm (7/8"), then a 20 mm Bolex 8mm projector lens that focuses the image from the fisheye toward the relay lens, which is from a laser copier. Then follows an objective lens from a small binocular, which collimates the light toward the actual camera lens, which is the rear part of a C-mount video "pinhole" lens. The pink rings are just holders for the components, all turned to 22 mm diameter. The angle iron is attached to the camera lens with masking tape - simple, but workable for this test!

Since all the optical components are achromats, the chromatic aberrations should be minimal. There is quite a bit of spherical aberration, though. I already know that the edge sharpness won't be perfect, but the intended use is for closeups of flowers and insects, still showing a relatively in-focus background. A 1.7 mm lens has an incredible depth-of-field (2" to infinity) even fully open - which in this case is around 5.6 to 8 due to all the optical components.

I'll post a video when I get the project finished - I will yet have to make a system of threaded tubes (total length about 250 mm, 10") in order to do a final assembly - thanks to my hobby lathe, that should not be too difficult a project...

Demo video here: https://www.magiclantern.fm/forum/index.php?topic=26804.msg242418#msg242418

Thanks, ML700D and Walter! I didn't know the correct tag, apparently IMG need to be in captions and/or the /description is necessary? (Me being a geezer noob... )

Over 20 years ago I bought a Canon 13x zoom, 7.5 - 97.5 mm, f 1.4 at an auction held by a production house here in Helsinki, Finland. They let go all of their ENG cameras.

I paid only 20 euros ($22) for the lens, but found that even when adapted to the EOS M and using the 3x feature in ML to remove the vignetting, there was horrible aberrations; at f 1.4 it was totally unusable. To get any sharpness at all, I had to stop down to about f 11. How come it was usable by the previous owner?

Took me some years to stumble on the reason for it, when I finally found a technical paper explaining why it was so atrociously bad at full aperture:

"Offsets in back focal distances for television cameras with CCD sensors"

You can read the full paper here: https://tech.ebu.ch/docs/tech/tech3294.pdf

Well, this sleuthing told me that the lens was designed with these aberrations! In a 3-CCD camera, there is a block of color-separating prisms, splitting the light into red, green and blue components, each for a single black-and-white sensor.

Those prisms counteract the lens distortions, and provide a sharp image on the sensors.

So, I made a block of glass to fit inside the lens mount! That block consists of two binocular angle prisms glued together with optical UV-glue. By sliding the prisms' long sides along each other, I could adjust the thickness of the block between 30-36 mm, and the ends were absolutely parallel. Ideally, the block should have been 40 mm thick, but that much glass wouldn't have fit behind the lens, and in front of the camera shutter. I had to settle with 35 mm. Not perfect, but usable...

There still is some chromatic aberration that won't disappear when stopping down, and some spherical aberration (fuzzy halo around highlights) visible at apertures larger than f 4.

Here's an example, showing the wide zoom range, shot at f 4:

https://www.youtube.com/watch?v=MED-N2X5YEU

This certainly isn't perfect, edges are soft and "rainbowy", but for shooting concerts on a stage with spotlighted soloists, it's good enough...

[Canon 13x zoom, 7.5 - 97.5 mm, f 1.4]

Canon 13x zoom, 7.5 - 97.5 mm, f 1.4

I mentioned this lens in a post long, long ago, but I have significantly improved its performance since then, Using the ML 3x crop feature.

Here's a still photo of the lens mounted on the EOS M:



Note the dark grey tube behind lens & camera, it contains the secret of the improvement!

Detailed explanation in the "Share Your Videos" thread: https://www.magiclantern.fm/forum/index.php?topic=26787.msg242174#msg242174

I'm using the "latest build 2018-07-02" for the EOS M - are there any newer? If so, I haven't found them, despite searching...

Yes, I'm recording H.264/MOV, and I meant Mbit/s - that's what QuickTime reports when I look at the files.

QT reports a bitrate for "default" MOV video around 45 Mbit/s - that's what has confused me, since "native speed", as you say, is 41 MByte/s - those numbers are too close for comfort, even though one is 8x the other.... 

But 2x normal bitrate means only about 11 MBytes/s - well within both camera and card specs.

"Kingston Canvas being incompatible" - just with overclocking, I assume?

I've never gone into RAW (would hamper my workflow too much), but I use ML for the 3x zoom feature, enabling me to use a plethora of C-mount lenses I have, including a Canon 7.5 - 97.5 mm, 13 x zoom... 

Long time, no chat, friends!

Today I experimented a little with a "Kingston Canvas Select Plus" 32 GB HC1 card in the EOS M, and was very surprised - it worked well at 2 x normal data rate, i.e. around 86 Mbps.  It looked like the camera buffer never exceeded 30% during short takes (didn't shoot any long ones), so would this be safe to use, or would it overheat camera and/or card?

At 2.4 x rate, slightly over 100 Mbps, the buffer filled up quite fast, and recording stopped after less than 10 seconds.  But I wonder - is the EOS M even supposed to work at such speeds? 

I also tried lower bit rates, and found that even 0.4 or 0.5 gives enough quality for recordings that will be uploaded to YouTube - which will degrade the image regardless of original quality...


BTW: Did I ever post a link to a 30-minute documentary I shot with two EOS M cameras for Finnish TV? The subject is hot air ballooning - can I put the YT link here if there is any interest? 

One quick question about the intervalometer and/or low fps settings:

If the battery runs out during shooting, will the file always be saved correctly? (I tried a search, didn't find anything...)

I'm desperate...New EOS M ML user here, installed FD Lenses with the Pixco adapter, everything looks great on the viewfinder, settings, aperture changes etc....but when I hit the Red Dot Record Button NOTHING HAPPENDS... no recording. Anything that might help this newbie out?

As Walter says, use the C.Fn-7 Release shutter w/o lens setting.

It is factory set to "off", meaning that you can't either without a lens, or with a lens that doesn't have the necessary electric contacts. According to eBay pictures of the adapter, it doesn't have the contacts.

This has nothing to do with ML at all...

You also get a sharper image and much more dynamic range to work with.

Exactly. I'll get that faster card before asking any more questions... 

Of course. What else should it be? Short snippets? There seems to be so many basic misunderstandings around what´s going on. I really can´t point to any that basic threads but before settling abc there will only be confusion.
Oh, and your card is probably not close shooting raw. But I won´t even open up the can of worms around sd card discussion. I am guessing you have a lot of spare time so using search and really dig into this forum should help out a lot.

OK, I'll stop bothering you now ...

- and maybe try a faster card some day, since with "true" 1920x1080 (instead of the basic 3x mode) I could get that little extra 10% wide-angle coverage from the Canon 12.5-75mm f1.8 C-mount lens I have. (Canon's EF-M zoom lenses really don't work well for video, since the f-stop changes during zooming.)

Thanks to you all for your help, in any case!

[always]

Works over here. Maybe you have a shitty SD card. And. You absolutely won´t be able to shoot h264 with this mode. This seems to be the real issue here. By now you should be able and determine what is what and what can be done and not. At least by viewing your recorded file. Either shoot raw and get exactly what you want or live with what you get with h264 calling it 1x1, 5x5, less than 1080 or something else. No hidden extras here.

I undestand I can't get h264.

Do you mean that MLV recordings are always raw, and just short snippets? The card should be OK, 32 GB Kingston Class 10/U1 ?

When you are in magic lantern menu, on Movie panel, stay on first top option and press set - you will see a lot more presets available.

Got them, including "x5crop 1920x1276 frtp" - but ML insists on shooting RAW for just 2 seconds even when I set RAW to OFF.

Tried those settings, got several CRASHES - needed to remove battery.

Also, before trying to record, the display overlay was in 5x or 10x mode plus 4 arrows, couldn't get a "normal" display mode. Very slow display refresh. When I could record, it was only for a couple of seconds, then it "automagically" stopped.

However, MLV did show the snippets I was able to record.

ML insists on keeping RAW on, even when I set it to off, it goes back to ON.

Do I have the wrong version? (crop_rec_4k_mlv_snd_raw_only_2020Oct06.EOSM202)

Am I missing something obvious? Older versions listed a few days ago get a 404 error. (Please have patience with me, I'll be 70 next year...)

Use e.g. "2.5K 1:1 centered" mode and set it to 16:9. Voilà: 1920x1080.

Thanks, I'll try that. (Not very intuitive, though... )