DIY: Adding a speedbooster to a BMPC 4k

I ran across a post where someone talked about adding a speedbooster to a BMPC 4k.
So I decided to attempt it.
It was quite easy.
I had a Viltrox speedbooster. I removed the lens, removed the ring inside the BMPC cameramount, and simply dropped it in.
Using some rimguard material to keep it in place and centered.
Here you can see the difference.
Same lens, same position same lighting.

Speedbooster.jpg (725.97 KiB) Viewed 6661 times

Lens.jpg (368.65 KiB) Viewed 6574 times

lens installed

Whats the rimguard material? Are you reaching near and far focus properly?

Whats the rimguard material? Are you reaching near and far focus properly?

Yep, focus is fine.
Rimguard Is a car wheel rim protector.

Can you post pics? better/bright ones?
Of the rimguard too?

These are the rim protectors. But I got black.

https://rover.ebay.com/rover/0/0/0?mpre ... 3165153158


I also found a plastic gasket thing that I them pushed on. top of the rim blade, and between the 2, it completely centered the lense.

Camera mod 2.jpg (641.04 KiB) Viewed 6448 times

Camera mod.jpg (860.8 KiB) Viewed 6448 times

I use metabones speedboosters for my bmpcc and bmcc. Both nf to mft. I also have a RJ lens turbo 0.72 eos to mft, I used use with my gh4.
The the Yashica Yashinon DX Auto 45-135mm 3.5 is one of my favorite lenses. Old, soft, chipped front element, parfocal, lovely lens. It has a m42 mount, so no adapter for nikon possible as the flange distance for m42 is too short.
Turns out metabones 0.64 glas element fits the RJ lens turbo thread as well.
So I swapped the elements and used yashica 28mm prime, as you have to take off and on the the lens combo from the camera all the time, to fine tune the lens element in the RJ housing to reach infinity. I then attached, the short of one kg weighting, Yashinon on the 'turbobooster' only to find out the lens was no longer parfocal. So I did the "calibration" all over, this time with the heavy Yashinon attached. When that was done all other eos lenses were fine too.
Long way to tell you your internal "speedbooster" might be fine on first sight , but ...
since the slightest difference in distance makes a huge difference in outcome I have a hard time believing that just dropping in an element did the trick. Do you have any zoom that is parfocal or have a close to parfocal behavior to check? If not, non of the above might be a problem...

I checked it with 2 zoom lenses, that seemed to stay in focus as I zoomed. Focus peaking would happen along the zoomed path. I'll try it again today, and post a link to a video.

More testing.
You're right. Focus isn't 100% there.
I need to find a way to get the speedbooster lense to sit a little lower.

Hope you find a way, success!

So is this like a lucadper for the p4k?


Ricardo Marty

So is this like a lucadper for the p4k?


Ricardo Marty

Yss

So is this like a lucadper for the p4k?


Ricardo Marty

So you mean that we could have all the be
Yss

So you mean we could have all the benefits of a speed booster like larger image size and an extra stop with an MFT lens?

Ricardo Marty

So is this like a lucadper for the p4k?
Ricardo Marty

Yss

PRODUCTION 4K not Pocket 4K
EF mount not M43

So is this like a lucadper for the p4k?
Ricardo Marty

Yss

PRODUCTION 4K not Pocket 4K
EF mount not M43

Correct

So is this like a lucadper for the p4k?


Ricardo Marty

So you mean that we could have all the be
Yss

So you mean we could have all the benefits of a speed booster like larger image size and an extra stop with an MFT lens?

Ricardo Marty

Correct

Any reason this wouldn’t work for the 2.5k EF?

Thanks!

Any reason this wouldn’t work for the 2.5k EF?

Thanks!

No reason at all

Wow, Please make this markapter a.s.a.p I'm sure you can find an o ring type that could work or maybe a 3d printer project and then sell them. (just don't get carried away)

Ricardo Marty

More testing.
You're right. Focus isn't 100% there.
I need to find a way to get the speedbooster lense to sit a little lower.

Why dont instead try adapting it to the rear of the lens?


Ricardo Marty

I went down this route a few years ago with a friend and colleague's BMPC4KEF and the optical cell from a Speedbooster Ultra of 0.71x at the same time as I was offering it up to the "big" URSA. The correct position of the Speedbooster optical cell for the image to be distortion-free and free of soft corners, requires the flange face of the mount to move rearwards about 4mm.

You can observe how far back inside the generous workspace of the URSA turret the Nikon flange face had to be repositioned for the Speedbooster/Nikon lens combination to be optically correct.

URSA 4KVA SPEEDBOOSTER1 RESIZED.jpg (139.73 KiB) Viewed 5793 times

That is not possible with your camera as there is cast bodywork and electronic lens control fittings in the way. You can cheat a little with the position of the 0.71 optical cell but it will not be satisfactory except in the instances where the lens on front will focus past infinity. You may still encounter side-edge and corner softness with wide-angle lenses.

I tried with Nikon F-Mount lenses. The F-Mount flange face is 2.5mm further forward and there still is not enough workspace for the lens to go back far enough. The tail structure of the lenses was in interference with castwork in the throat of the camera.

In your experiments, protect the EF-Mount lens control pins with a strip of insulating tape. If you short those, the camera electronics may lay down permanently. If the little return spring for the release button flies out and goes mulga, there is a fix if you cannot get a new part.

The flint spring out of a Bic cigarette lighter is a fair substitute. It has to be shortened with a Dremel cut-off wheel and the diameter has to be wound in just a whisker by gripping both ends with good pliers and twisting it up tight around a small jeweller's screwdriver shaft.

It is best to trim it after you have wound it smaller because there is inevitable damage to the coil-ends from the pliers.

Ricardo.


I am guessing you are suggesting moving the flange face on the lenses furthur forward.

With third-party lenses like Rokinon/Samyang Xeen lenses and their many choices of mounts, making custom rears for Canon EF or Nikon Mount may be feasable but you would have to find 4mm to take out from somewhere.

It is a hell of an expensive lens to be modifying.

This would move the lens body rearwards into near-to-correct collimation with final trims available by adjusting the position of the 0.71x Speedbooster cell.

This however does not deal with the problem of rear structures of the lens coming into interference with internal structures within the camera throat.

There may be some fat in both the rear of the lens body and the camera throat which can be dressed out. The possibility of damage to the sensor and its PCB is very real. The sensor type is apparently intolerant of heat and low humidity.

I expect it may not be tolerant of high frequency vibrations from machine tools like a Dremel cutter/engraver.

Ricardo.


I am guessing you are suggesting moving the flange face on the lenses furthur forward.

With third-party lenses like Rokinon/Samyang Xeen lenses and their many choices of mounts, making custom rears for Canon EF or Nikon Mount may be feasable but you would have to find 4mm to take out from somewhere.

It is a hell of an expensive lens to be modifying.

This would move the lens body rearwards into near-to-correct collimation with final trims available by adjusting the position of the 0.71x Speedbooster cell.

This however does not deal with the problem of rear structures of the lens coming into interference with internal structures within the camera throat.

There may be some fat in both the rear of the lens body and the camera throat which can be dressed out. The possibility of damage to the sensor and its PCB is very real. The sensor type is apparently intolerant of heat and low humidity.

I expect it may not be tolerant of high frequency vibrations from machine tools like a Dremel cutter/engraver.

Why does the lucadapter work?

Ricardo Marty

Ricardo Marty.


"Why does the Luca Adapter work?"

The honest answer is I don't know. I have not tested his adapter so I cannot say with authority if it works or not. From reports by owners, it seems that it does.

If wide-angle lenses achieve infinity focus at wide-open apertures, then it will be properly working. If infinity focus cannot be achieved with modern wide-angle lenses set at T1.5 or thereabouts, then the adaptor will not be as good as it could be.

For most purposes where the lenses are chosen for shallow depths-of-field, a focal reducer which is not accurately set up will work well enough. The focus marks on the lens barrel will not read true.

If you are chasing a wide-angle image panorama of open plains and mountain backdrops, you would need to have that lens set at a pinpoint aperture to deepen the depth-of-field enough for distant detail to be sharp.

Even then the result may be soft altogether depending upon how far past infinity focus the lens will turn. The image may also be soft in the corners. At the necessarily tight aperture settings, you may also introduce diffraction.