BMMCC - yet another controller

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Andrzej Kryt

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BMMCC - yet another controller

PostFri Dec 08, 2017 3:33 pm

I'd like to share my idea for controller - thanks to Blackmagic Design for the expansion port in this great little camera.

My main assumption is to make Micro Cinema Camera more comfortable to use in the field, something more similar to DSLR rather than full blown shoulder rig. I developed hand grip with built-in controller, getting hand held mini rig just little bit bigger than DSLR.

Features:
- Based on Arduino
- Uses S.BUS to control REC, focus, and all other functions, including firmware v4.7 ones
- Powered by 5V provided by Micro Cinema Camera
- Contains DC-DC converter (input voltage 3-30V), so that it can feed BMMCC with 12V - the goal is to have single battery to power camera and monitor, but it is not a must, both can be powered with their own batteries
- Equipped with REC button, analogue joystick (to operate focus and zoom - the further from centre, the quicker the change is) and encoder (all other functions), 5 LED-s are used as simple "user interface"
- Standard rosette is used to mount to cage or any other hardware, so the grip can be rotated
- Housing made of PLA (3D print) and aluminium

Starting point:
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Fully equipped set. I built custom cage specifically for my needs, but the controller can be used with versatile cages available for this camera:
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I use 5" monitor, it's difficult to find something smaller:
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In this position it can be held like video camera, balance depends on lens attached, again smaller monitor would be better:
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Operated by index finger and thumb, like most of hand grip controllers:
Image

My experience is that it is not so difficult to build a desk prototype. The most difficult and expensive part is the housing actually. Except the housing it contains custom designed PCB inside. Now this is fully working device, nothing else to do, except anodized aluminium elements to replace existing shiny ones.
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Stu Aitken

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Re: BMMCC - yet another controller

PostSun Dec 10, 2017 1:39 am

cool - a few of us have been looking at this but well done for actually getting to a working prototype!

perhaps Dmitry Shijan might chip in on the getting it made front - he's had few pieces made (small expansion port box, arris rosette mount, HDMI clamping bracket) and I think he'd be a useful person to chat through some options

he also has mockup very similar to this - here was my latest though its still very much virtual:

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Screenshot 2017-08-17 23.17.45.png
Screenshot 2017-08-17 23.17.45.png (159.19 KiB) Viewed 7562 times
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Ian Henderson

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Re: BMMCC - yet another controller

PostMon Dec 11, 2017 11:57 am

Very nice work - what’s the chance of either of these becoming a real production item?
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostMon Dec 11, 2017 3:25 pm

There is some chance for manufacturing, but it's not obvious to build the business case, everything depends on the number of interested film makers :)

Electronic components, including custom PCB is very affordable and quite easy to get into production.

But the issue is in housing...
- Aluminium elements are manufactured on CNC machine - cost very highly depends on orders volume: let's say 1 piece cost gets reasonable with at least 100 pieces manufactured in one batch, with <10 pieces batch the cost gets insane.
- For plastic elements, injection machine can be used for mass production, not applicable here. 3D print is ideal for durability and cost, precision is sufficient as well. But aesthetics in this case is quite away from what one could desire. I checked 3 different manufacturers but there is no much difference for FDM, other technologies are too expensive in my humble opinion.

On my pictures you can see 0,3mm layers, front element is made of PLA (shiny) and back is made of ABS (mat)

If ABS is used instead of PLA and layer decreased from 0,3mm to 0,1mm, then it would look better, but again cost would be higher.

So the point is open, everything depends on potential number of pieces to be manufactured. The controller I present can be very easily adopted for Micro Studio Camera 4K, there is no +5V feed provided by this camera, but the controller can be powered by external source. It extends little bit the application area.
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostMon Dec 11, 2017 7:19 pm

Feels like beta prototype but overall seems like correct direction.

There are many threads on bmsuser and other forums but mostly theoretical and concept design. I have similar attempts to but still can not manufacture even simpler one button PWM test sample. I'm not familiar with coding so never look for S.Bus concept. If it helps i would like to share some concepts and ideas too:

Joystick remote concept:
One joystick + rotary wheel + separate record/stop button can do all the work.
joystick left-right parameter selector.
joystick up-down value change.
joystick middle press switches joystick to 4 fixed user preinstalled function buttons mode (for example: click LEFT - autofocus, click RIGHT - auto iris, click UP - iso value up, click DOWN - iso value down)
Rotary wheel can control current selected parameter same as joystick but smoothly, or be used in user preinstalled function mode (for example set it to manual zoom control).
Settings change can be monitored with some kind of 0.5 or 0.9 inch micro OLED display in simple one line text mode [PARAMETER: VALUE]

From personal experience:
CNC manufacture. Prices are very different. It depends of size, complexity 2D flipped parts are cheaper than 3D. Known camera rig manufacturers in China may help. Min order usually 50 copies. Sometimes manufacturers may agree to 20 copies. Anyway it is all around $500-1000 per batch. Also you need to find someone who can draw in real CAD programs or learn something like Fusion360 or similar software.

Hot plastic injection molding. It may feels simple but it is not. Parts larger than 2-3cm needs larger machines to fill the form. You need CNC aluminum master model which is also expensive and have limits. Straight 90 degree angles in master model don't allowed because plastic part may stick forever to hard metal shape, so it needs more complicated 3D model than usual. Need draw model in real CAD programs. Quality may be poor because there tons of realtime factors you need to check during process. If you make mistake or want to change something you need order new expensive CNC aluminum master model.

FDM 3D print with manual finish. It is really user friendly method. Print with quality FDM 3D printer, hand develop with knife and sand paper, paint with acrylic paint for plastic. Hand develop may be longer than you expected. So be ready spend 2-5 days for each part. Large parts printing may take long time.
ABS is not a perfect material. It is better use PET modifications. Way stronger and easy to develop.

Silicone mold rubber and liquid urethane plastic casting and manual finish. This is the method i working around. Master model printed on any DLP or Objet 30 printer, hand sanded. Silicone mold, Smooth Cast Onyx urethane plastic, vacuum camera, and you can manufacture 5-6 parts per day from one silicone mold. Same as parts from FDM printer you can paint it with acrylic paint for plastic or any other. Usable for large parts. Silicone is most expensive part, but may hold around 30-100 copies. This method needs long preparation process to start manufacture from scratch. Due long preparation process outsource molding and casting sometimes may cost close to CNC manufacture.

Ergonomics research. based on mix of commonly used in many other cameras and standalone handles. This shape works very well and very compact in size which is friendly to BMMCC camera.

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Andrzej Kryt

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Re: BMMCC - yet another controller

PostTue Dec 12, 2017 8:07 am

Dmitry, thanks for sharing your experience. I can see that we face very similar challenges. In my first prototype I used 8 PWM channels servo controller and PWM-S.BUS converter for 4 channels (very little programming), but finally I can see that Arduino can do the job very well with single S.BUS line, very tidy solution and it is not so difficult to program.

Please mind that big REC switch with spring inside is very noisy, you will hear clang recorded, at least it was the issue in my first prototype because the button is close to microphone. Tact switch is much better, the problem is gone.

Be careful about plug you would like to use for camera connection. Mini jack seems good option because it's compact and cables are so easy to get/replace, but I don't like the idea of camera's +5V and GND connectors exposed in case the cable is unplugged from the controller. I use industry M8 connector with 4 pins, it can be attached very firmly and is smaller than mini XLR (often used in video equipment).

I prepared short presentation how to operate the controller (sorry for shaking picture but my secondary tripod is too small):
I use rotary encoder with button built in: parameter/function selection by press, value change by rotation.
Then there is REC button and joystick in front of the controller. Analogue joystick is used for functions that require smooth action: focus and zoom.

I will check feasibility for OLED display, but at the first glance it will be difficult to fit in place of LED-s, currently I use area 5mm x 12,5mm, anything larger will conflict with internal frame.
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Stu Aitken

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Re: BMMCC - yet another controller

PostTue Dec 12, 2017 1:24 pm

Ian Henderson wrote:Very nice work - what’s the chance of either of these becoming a real production item?


this is the issue really - small batch manufacturing is not a thrilling prospect for many reasons (seeing something you designed become 'real' is maybe the only plus)

affordable + well made (even reasonably acceptable) is very difficult to achieve on small production runs with a design that needs even a few separate parts - ask Shijan how much manual finishing and assembly work he had to do on his little expansion boxes, as simple as they seem...

...and then you have the whole issue of supporting a product out in the wild on top of that.

my aim was always to do what would amounts to a proof of concept and a 'one off' i could personally use then maybe publish the design and methodology so someone could easily copy it - sort of 'open source' manufacturing, but I appreciate that will certainly not be for everyone
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostTue Dec 12, 2017 10:32 pm

Well, it all depends on requirements. For instance I don't mind ugly look of 3D print as long as the element is functional and strong enough. But I'm accustomed to DYI projects which are always far from consumer electronics regarding the look but much more well suited to my needs.

Dmitry has nice ideas, I find it as good progress. Still it's all about getting nice looking product, worth digging to some extent.

The idea of 'open source' manufacturing seems interesting, let's say for me this is not a problem to share 3D models so that anyone can order parts at local manufacture according his/her budget and requirements, but it will work for plastic parts only. For CNC aluminium it's completely different story: you can order 1 piece for 500$ or 100 pieces for 10$ each... Then there is the matter of electronic components an soldering, and I cannot guarantee that particular encoder type I used for modelling is available everywhere. After all it is an option for DYI enthusiasts only, I can imagine that usually film makers don't want to spend time on crafting the gear :-), so we are back to product feasibility study.
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Stu Aitken

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 4:59 am

yep - I reckon 100 orders is about the minimum you would need to hit any kind of acceptable price point given the relative complexity - as you point out:

CNC chassis (with a well designed and strong case you could maybe omit this)
plastic mouldings or 3d printed shell parts (casing)
possible over-moldings or rubberised inserts, or glued on material for better comfort
electronics (though using low cost arduino clones can reduce this
HW controls (and how these are reliably mounted, and connected to mail electonics board
actual assembly and QA
etc

if you pull apart something similar like say a game controller you can see how much they rely on mass production technologies like plastic injection molding (molds can easily cost $10k +) custom PCBs and flexible connectors - this all becomes cheap if you can sell 1000s of units to amortise the setup costs but is prohibitively expensive on short production runs
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Howard Roll

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 7:47 am

Ha! That's even better than cutting a PS4 controller in half.

I think wood we be a strong candidate for a material that could keep costs down and be easier to work than aluminum and be much cheaper than an injection molded or even printed design. Bare Ergocine grips are down to $200 dollars, there's a possible partnership opportunity there if you've got the gift of gab.

I'm all about a DIY a bag of bits and the sketch for $50-$100 bucks and letting people deal with the mess of the actual structure themselves.

Andrzej, what Arduino are you using for your prototype?

Looks cool.
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Ian Henderson

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 7:54 am

I like this idea.
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 8:11 am

Here it is, nice and shiny PCB inside:

Image

Image
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 12:13 pm

Howard Roll wrote:Andrzej, what Arduino are you using for your prototype?


This is Arduino Pro Mini - huge choice of cheap clones, sufficient number of in/out pins in small factor. The only disadvantage is lack of USB port so that FTDI tool must be used to program it. Additionally there is TTL/RS232 converter needed for S.BUS output - the little chip visible under Arduino board.

Alternative option worth to consider is Pololu A-Star Micro: even smaller and it contains USB for ease of upgrades, but it costs ~3 times more than average clone of Pro Mini. Still the price of controller is just a fraction of the housing cost.
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Xtreemtec

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 1:47 pm

Kim may i ask were you get those round potmeter knobs from with the white dot on it? I'm looking for such knobs for 2 months now for our fiber unit..

Have you guys ever considered to 3D print and then put the part in a tumble shaker with sand? Or other idea.. 10 minute sanding job and finnish off with Plasti-dip? 8-) Plasti-dip would be easy for parts up to this size.. And does make a very smooth surface.
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 2:40 pm

Kim Janson wrote:SBUS works on 5 volt levels, it is just inverted.


Correct, TTL/RS232 converter (PL2303 chip) is used as inverter, bare Arduino cannot do it.
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostWed Dec 13, 2017 3:44 pm

Xtreemtec wrote:Have you guys ever considered to 3D print and then put the part in a tumble shaker with sand? Or other idea.. 10 minute sanding job and finnish off with Plasti-dip? 8-) Plasti-dip would be easy for parts up to this size.. And does make a very smooth surface.


Any FDM 3D print is too uneven for tumble shaker with sand. You need to grind about 0.5-0.8mm to make it look even. When you can try to put it to tumble shaker with sand. From my sanding experience ABS probably too soft for that. CoPET or similar harder plastic may work well. Actually hand sanding is very easy on larger simple streamlined objects without straight geometry surfaces and chamfers.
Any regular paint coating just tear off too fast from handle grip, so that Plasti-dip seems like very nice option. Fat rubber grippy surface must work great. Never use it but maybe will test it.
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostThu Dec 14, 2017 5:59 pm

Andrzej Kryt wrote:Dmitry, thanks for sharing your experience. I can see that we face very similar challenges. In my first prototype I used 8 PWM channels servo controller and PWM-S.BUS converter for 4 channels (very little programming), but finally I can see that Arduino can do the job very well with single S.BUS line, very tidy solution and it is not so difficult to program.


Same here :D I used PWM-S.BUS converters but lost that idea because seems like useless and limited way to go for batch production.
Image

Andrzej Kryt wrote:Please mind that big REC switch with spring inside is very noisy, you will hear clang recorded, at least it was the issue in my first prototype because the button is close to microphone. Tact switch is much better, the problem is gone.


Yes, most latching buttons are noisy and hard to press, but i find one button that almost silence and very soft to press. Take a look:
Image

Andrzej Kryt wrote:Be careful about plug you would like to use for camera connection. Mini jack seems good option because it's compact and cables are so easy to get/replace, but I don't like the idea of camera's +5V and GND connectors exposed in case the cable is unplugged from the controller. I use industry M8 connector with 4 pins, it can be attached very firmly and is smaller than mini XLR (often used in video equipment).

Looks very interesting, but i never see those connectors before. But i still prefer mini jack because it can be free rotated, very common and inexpensive. It is also possible to use common 3.5mm socket rubber plug to protect it.
Just in case if you decide move to minijack in future, there is a common pinout for S.Bus which was developed and promoted and used by group of forum members:
S.Bus power (tip)
S.Bus signal (ring)
S.Bus ground (sleeve)

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Stu Aitken

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Re: BMMCC - yet another controller

PostThu Dec 14, 2017 8:34 pm

the ps3 'move' nav controller was another option I was considering - plenty of buttons, trigger and a joystick

you can pick them up very cheap

it has a micro usb port built in - might just be enough room inside to shoehorn a small arduino clone in there, if you could replace the inbuilt li ion battery with the 5v in from the camera instead

ps move.jpg
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Howard Roll

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Re: BMMCC - yet another controller

PostThu Dec 14, 2017 10:27 pm

It's pretty amazing how economically something can be created once the economy of scale comes into play. 10 years ago the specs for the Phantom 4 camera alone would have been jaw dropping, if you told me it could fly as well I'd think you were on drugs, if you told me it was $1500 dollars I'd know you were on drugs.
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Xtreemtec

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Re: BMMCC - yet another controller

PostFri Dec 15, 2017 10:35 am

Amazing shots.. Did you had the camera far out in front of the proppelors so you can turn the camera without seeing them? or did you fly inverted?
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Stu Aitken

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Re: BMMCC - yet another controller

PostFri Dec 15, 2017 5:20 pm

Arduino and ps3 move controller:



looks like its using BT to communciate:

Last edited by Stu Aitken on Fri Dec 15, 2017 5:24 pm, edited 2 times in total.
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Denny Smith

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Re: BMMCC - yet another controller

PostFri Dec 15, 2017 5:23 pm

The problem is though that most lenses that provide electrical iris and focus control, do not do that very well for video use. They are somewhat stepping. Today there is no other than commersial reasons for that... Kim J.


Yes, I agree Kim, this is the issue with most still camera zooms in the mid price range, and even in higher end models. They were designed for still photography were stepping and parfocal are not issues, as a still camera does not pull a “live zoom”.

However, I have found one MFT Zoom, which is parfocal, very fast focusing, and no stepping... Iis the new Panasonic Leica 12-60 f/2.8-4 Zoom. It has a new silent focus motor and steeples iris control, dead smooth. Now, only it were a constant max f/stop, then it would be grand. :roll:
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Stu Aitken

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Re: BMMCC - yet another controller

PostFri Dec 15, 2017 5:36 pm

BTW for those not familiar with the arduino platform, the larger 'uno' board you see in these videos is functionally identical to the MUCH smaller nano sized boards (the latter just use miniaturized surface mount components, including the ATMega microprocessor but they are the same thing just in different form factor)

Image

additionally you can get arduino compatible boards (these are not official arduino's - or cheap copies - but are similar and generally compatible with the programming ecosystem) with BT on board like this DRrobot version so you wouldn't need a dongle hanging off a usb port as in the youtube video I previously linked to

https://www.dfrobot.com/product-1122.html

Image

so a possible 'cheap' solution would be something like Shijan's expansion box but bigger and with a BT enable arduino inside that connects to the camera expansion port directly and then a BT game controller like the PS3 move navigation unit (or the wii ninchuck) as the hardware interface that would talk to the 'smart' expansion box over BT
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Stu Aitken

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Re: BMMCC - yet another controller

PostFri Dec 15, 2017 5:58 pm

and now I think of it you could just use a BT smart phone also - if one creates an appropriate app :)
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostSun Dec 17, 2017 2:45 am

Some test samples arrived today from casting factory. This is made of liquid urethane plastic.
Pros:
Nice quality. Rugged, not too hard not too soft material. Fine texture surface possible without additional painting. 100% neutral black color. They have soft and hard rubber-like samples too. It is also possible to insert metal elements inside liquid urethane during casting.
Cons:
Larger parts needs larger amount of silicone and urethane which is expensive.

P.S. I desaturate image because color moire all around fine texture

Image
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostMon Dec 18, 2017 8:37 pm

Dmitry, it looks pretty well. Have you tried to cast some shape yourself or checked with casting factory directly? I have seen few how-to videos, silicone form seems to be quite easy to create. I'm just wondering if 3D models should be somehow optimized for this method.

Stu, Kim, the concept to reuse a controller already available on the market is little bit different from my intention: my priority is to use it as hand grip to be attached to a cage. However the idea to communicate via Bleutooth is already materialized, if you are interested, please look for One Little Goat, it can be controlled with a smartphone.
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Stu Aitken

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Re: BMMCC - yet another controller

PostTue Dec 19, 2017 3:51 pm

Hi Andrzej

yeah I get what you are trying to do :)

maybe we hijacked your thread a little (a lot?), but the discussion often comes down to how the hell you manufacture more than a couple of units and that's why things like using existing controllers come in

again props for actually getting to the working prototype stage!
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostTue Jan 16, 2018 4:24 pm

I added new feature, probably I'm not the fist who invented something like this, but it's useful anyway. And it demonstrates benefit of having expansion port in BMMCC.

The starting point: while camera is in gimbal, focus cannot be controlled by lens ring, so the controller is used for that. However small joystick is sometimes not so convenient as lens ring. I developed a feature to pre-set focus value: first focus is set by the joystick, then the setting can be stored. It is possible to register two values. For details how it works, please check the demo:


Image
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostWed Jan 24, 2018 3:40 pm

Hi All,

I'm considering small batch production, the only issue left is to replace 3D printed plastic parts with something that looks better, I'm working on it. Calculation shows the price level around 220-250 USD per piece. Do you consider it as too high?

In current version the controller firmware can be updated only with FTDI tool. With some higher cost (5-10%) I could use different Arduino board with USB for easier upgrades. Do you find it beneficial?

Any feature requests?

Your feedback will be appreciated.
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Stu Aitken

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Re: BMMCC - yet another controller

PostWed Jan 24, 2018 6:34 pm

Andrzej Kryt wrote:Hi All,

I'm considering small batch production, the only issue left is to replace 3D printed plastic parts with something that looks better, I'm working on it. Calculation shows the price level around 220-250 USD per piece. Do you consider it as too high?

In current version the controller firmware can be updated only with FTDI tool. With some higher cost (5-10%) I could use different Arduino board with USB for easier upgrades. Do you find it beneficial?

Any feature requests?

Your feedback will be appreciated.


I would go with USB 100% - chances are it will need a firmware update at some point and end users will find that a LOT easier

the price you quote seems pretty realistic to me given I know how hard this is to do, but I suspect its too high for the market...
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Denny Smith

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Re: BMMCC - yet another controller

PostWed Jan 24, 2018 9:17 pm

Price is in line with other SBus controllers, even the BM Urs Mini grip is $200 and only offers three limited functions. The change in focus with the presets seems a little too fast and jerky as a result. Yiu might try slowing down the focus change Rste a little, to smooth out the challenge ge, like a live Cine focus pull from near to distance or the other way round.
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostThu Jan 25, 2018 10:26 am

I think price tag is highly depends of final quality. even if it is a DIY made thing for higher prices people usually expect well designed and solid product with tested ergonomics.
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Steve Watson

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Re: BMMCC - yet another controller

PostThu Jan 25, 2018 11:14 am

Hi,

another thing to consider is after sales support, returns, warranty, repairs etc.

Depending on territories there will be some kind of need to deal with those things for anything up to a year.(maybe longer, I'm no expert).

Something you need to factor into any price.
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Re: BMMCC - yet another controller

PostThu Jan 25, 2018 2:38 pm

Stu, Denny, Dmitry, Steve,

Thanks a lot for your replies.

Stu Aitken wrote:I would go with USB 100% - chances are it will need a firmware update at some point and end users will find that a LOT easier

You are right, Teensyduino seems good candidate, especially that it has 2 or 3 serial ports, and it doesn't require dedicated serial inverter, as Kim noted before.

Denny Smith wrote:The change in focus with the presets seems a little too fast and jerky as a result.

Done :-) In the demo there is immediate value change, so in fact it is as fast as the lens can do. I modified the code to change focus value by 1 step every 2 milliseconds (or to be precise 3,5 steps every 7 milliseconds because S.Bus frame is sent every 7 milliseconds, S.Bus value "resolution" and min/max constraints provide around 1300 steps - if the explanation is too boring, just let me know to shut up). I checked that 1 step every 7 milliseconds gives feeling the change is too slow.

Dmitry Shijan wrote:people usually expect well designed and solid product

Fully agree. I'm not afraid about toughness - the construction is composed of 3 mm thick aluminium sides, connected to internal frame elements. For production version the internal frame shall be made of aluminium. My prototype has internal frame made of 3D printed PLA, but even in this configuration it holds gimbal+camera+monitor+battery = 2,5 kg without bending or any other issues. So aesthetics is the only concern I have. Your method with silicone form mould looks promising, this is my next step to do.

Steve Watson wrote:another thing to consider is after sales support, returns, warranty, repairs etc.

I will look for some advisers, from technical side I have no issue to sort it out, but I have no experience with consumer post-sales support. Thanks for spotting this.
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Dmytro Shijan

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Re: BMMCC - yet another controller

PostThu Jan 25, 2018 3:10 pm

If you look at my reports in the thread in bmcuser forum, silicone form mould appears not too precise. It may work for larger parts but this method produce a lot strange unexpected surprises. It is better to use Aluminum CNC machined mould.

Aesthetics and overall look is really important. People just like good looking and professionally designed things. Technology is easily accessible, quality and accuracy requirements are very high these days.

For my opinion DIY stuff in small batches must be less expensive because you don't need pay for large offices, additional workers, advertisement, long term warranty for complicated electronics and so on. Manufacture and machining per unit may be more expensive because small batches, but overall final unit cost may be way lower because less additional side expenses.

Fot CNC parts try to deal with LanParte factory. They can manufacture small batches of CNC machined Aluminum alloy parts. Prices seems ok and communication is fast compare to other factories i contacted (Aminimart, Camvate, SmallRig).
BMMCC/BMMSC Rigs Collection https://bmmccrigs.tumblr.com
My custom made accessories for BMMCC/BMMSC https://lavky.com/radioproektor/
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Stu Aitken

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Re: BMMCC - yet another controller

PostThu Jan 25, 2018 6:09 pm

Andrzej Kryt wrote:S.Bus value "resolution" and min/max constraints provide around 1300 steps


unfortunately its not - I thought this as well, but according to Kristian at Blackmagic the camera truncates the sbus channel values from 11 bit to 8 bit (it simply ignores the 3 least significant bits of the 11 bit channel values) and then it only uses about 50% of the full possible range as well (presumably to account for inaccurate HW controls at the extreme ends of their adjustable range) so in practical terms you effectively only have around 7 bits of resolution or around 128 discrete values

hence focus and zooms are always gonna be a bit 'steppy' done this way
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Wayne Steven

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Re: BMMCC - yet another controller

PostFri Jan 26, 2018 8:41 am

Hats off to you guys.
aIf you are not truthfully progressive, maybe you shouldn't say anything
bTruthful side topics in-line with or related to, the discussion accepted
cOften people deceive themselves so much they do not understand, even when the truth is explained to them
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Andrzej Kryt

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Re: BMMCC - yet another controller

PostMon Jan 29, 2018 6:12 pm

Stu Aitken wrote:the camera truncates the sbus channel values from 11 bit to 8 bit

It is possible, I send 11 bit values, but I don't know what happens in camera. For IRIS and Audio Level 8 or 11 bits don't make a difference. In case of focus, my eye is not trained to count steps. But it's good to know anyway, thanks for the info.
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Stu Aitken

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Re: BMMCC - yet another controller

PostTue Jan 30, 2018 1:21 am

Kim Janson wrote:I am afraid it does not quite work like that. If it would, there would not be any big companies manufacturing huge volumes...

Dmitry Shijan wrote:...

For my opinion DIY stuff in small batches must be less expensive because you don't need pay for large offices, additional workers, advertisement, long term warranty for complicated electronics and so on. Manufacture and machining per unit may be more expensive because small batches, but overall final unit cost may be way lower because less additional side expenses.
...


agreed - the cost saving from lack of overheads is massively outweighed by cost of manufacture at a small scale

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