Thanks, Peter. One important advantage in going the monochrome route would also be the ability to have more than 3 channel, and the opportunity to change the colors of the light sources according to the film being scanned. That would be very helpful when scanning non-standard material (for example negatives, faded film, hand colored films, experimental films where the artist drew directly onto the film, tinted film, specialist film stocks, …).
Yes, all of the professional level scanners we build are monochrome sensors, and we do a separate Red, Green, Blue and Infrared pass (to capture a damage-matte). You then have to be able to register and combine the images fo course, to make a single colour RGB image with the damage matte in the alpha channel.
If using a bayer sensor, then you can still use a tri-LED light source, and adjust the light-mix accordingly for different film stocks, or to adjust for fade etc. We only use tri-LED light sources whether for Bayer or Mono sensors, but with the mono sensor, you have to be able to have the film stationary for the 3 (or 4) captures, whereas with a bayer you can have continous motion film, and trigger the LEDs to flash at a fast enough rate to ‘freeze’ the single frame for capture.
Either way you get full control over the light-mix for capturing.
All of the PGR cameras I mentioned are available in mono or bayer-colour.
To answer Digitap, the $295 camera does an excellent job, and is generally more than enough for Super8 home movies, I personally would move up to the $495 camera, but you are right, depending on the source you hit diminishing returns pretty quickly, and the $295 model gives extremely good pictures, and they scale up to HD resolution very nicely for viewing on current display devices.
I like to capture in higher resolutions so I can apply stabilisation and cropping and have it all happen at better than HD so that I can then scale down the result to HD, but realistically for most ‘family memories’ a 1288 x 964 capture scaled to 720P for final delivery looks amazing.
You just blew my mind, @Peter. I’m thinking of doing tests with that and/or the Blackfly. Been getting some interesting results with my 8mm setup using Raspberry Pi, but the image quality is nothing to scream about.
In general, my only problem with non-line-scanner cameras is figuring out a way to rebuild intermittent motion in a way that is reliable and cost-effective enough to make sense if we have to make small batches of them. I’ve looked at geneva gears, tore apart 10+ projectors, and in every case we’re looking at high tolerance parts that are hard to make.
I did find one cheap option, but it only works on film that is in good shape.
Of course, this issue it moot if speed is not a concern. You can move the film slow enough that blur isn’t an issue and then there is no need for intermittent motion.
Does anyone have any bright ideas on how to solve the intermittent motion problem without gutting/using old projectors? Or is that really our best shot at an affordable machine??
M
@Matthew “Does anyone have any bright ideas on how to solve the intermittent motion problem without gutting/using old projectors?”
There is, quite understandably, a lot of misconception surrounding the subject of home-made gate/claw mechanisms. It is instinctive to think that extremely accurate and high tolerance engineering is necessary (especially for the minuscule 8mm format), but that is not actually so. If it was, low-cost 8mm movie cameras and projectors of yesteryear could not have been produced.
Years ago, I was involved in the design of 35mm animation cameras for use on multi-plane rostrums, but have not considered this technology for many years - until recently when I inherited a large collection of films made by my father and his uncle, dating back to the early 1900’s. These comprise just about every format that exists up to 16mm, including the earliest that were hand-perforated.
I do not have projectors that will handle all these formats, and besides I know that many of the films are very fragile (not nitrate, fortunately) and may not survive the brutality of a projector. That is when I discovered the Kinograph website which I found very interesting. However, I can see that it needs a relatively expensive live-mode camera in order to capture the frame within a very few milliseconds, which I do not have. There are a few webcams out here that have full 1080 HD resolution (for stills), and excellent optics (which can be easily converted in seconds to macro), but their image chips are scanned (unlike DSLRs), which makes them unsuitable for moving subjects.
So, I revisited my past, and investigated if it was feasible to make a mechanism with my 3D printer (Ultimaker2) that would meet all my requirements. This time, I did a complete analysis of my earlier work, including a worst-case tolerance assessment. I was also able to adapt the design for 3D printing, which can produce parts that are difficult to make using traditional machining methods.
The result is illustrated in this animated image.
The dimensions are generic, and do not relate to any particular film gauge but, although some parts are quite small (especially for 8mm) they can easily be printed in ABS, nylon or carbon-fibre to the required tolerance.
For example, for Std8mm, the mechanism could have a pull-down of 4mm, with a claw-height of 0.85mm, given a tolerance of +/- 0.1mm. For larger gauges, this tolerance could be relaxed.
I have produced an Excel spreadsheet, which explains how claw mechanisms work, the relationship between pull-down and claw-height, and tables which show the trade-off between each of these parameters, for variable tolerances. There are pages that detail 9.5mm, Std8, Super8, and 16mm. I do not want to post that here, but if anyone has a genuine interest in it, then I am willing to email them a copy. My address is support@vitalsparks.com.
Jeff
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Amazing, @VitalSparks! Thanks so much for the handy Gif, too. Do you have any STL/OBJ files you can post for people to try out?
Sending you an email about the spreadsheet now…
If you don’t want to the hassle of an intermittent drive, then just use an LED ‘flash’ light source. It can easily run at 24fps or faster with no blur, the Muller works exactly that way.
You need an array of Red, Green and Blue LEDs to get enough light, and some large-ish capacitors to make sure you have enough juice to flash them reliably, but it works perfectly and the film can remain in constant motion. The only tricky part is you need a sprocket sensor to reliably trigger the ‘flash’ at the correct time.
Frank Vine manufactures a triggered light source that works perfectly for this, (he also designed the one in the Muller scanner) and it isn’t all that difficult to make your own, though it would probably make more sense to pay Frank to design one for you.
The PGR cameras I have mentioned in the other threads, (that start at a few hundred dollars), are global shutter and work perfectly with this method. You are right that rolling shutter cameras ar not a good choice for this kind of work.
A big part of the problem of intermittent drives is that they can damage fragile film, and that the mechanism itself is prone to wear, it has to cycle 170,000 times for every two hours of film, and you also have to have loops of film to cater for the movement itself to stop the film getting damaged or putting pressure on the drive system.
The low cost projectors of yesteryear are notoriously hard on film. The cheap cameras only handled the film once, and only every brand-new perfect film, so they could be quite tough on film and get away with it.
A flashscan system avoids those issues, but introduces the need to trigger via sprockets.
Sorry, don’t have anything ready for publishing yet, because the final design is still being iterated, and I’m working with 9.5mm, which may not be of any use to many people.
However, if anyone with a 3D printer is used to designing their own things with CAD, then here is the most essential snippet of information that is the heart of the design - the rest is common sense. This relates to that weird-shaped cam. It took me many hours to work that out, but in the end I got it!. I have found out since that the shape has been used for centuries for countless other things. It is called a Reuleaux Triangle, a rounded triangle, or a ‘constant width triangle’ - the latter giving a clue to how I am using it.
I was a bit miffed when I found those darned clever Romans got it first, but I bet they didn’t use it for a telecine rig. Or did they…
Here’s how to draw it -
Draw an equal-sided triangle, with sides exactly equal to the pull-down dimension you want (not the spacing of the sprocket holes - my spreadsheet details why). At each point of the triangle, draw an arc that bisects the other two points - that’s it, there’s the shape. To use it, rotate it about one of it’s points as I show in the gif I posted earlier. The rest you can work out for yourself by watching the gif.
Hope that helps.
Jeff
@Peter
I hear what you say about intermittent gates, and badly designed ones are bad news. The one I am working on is just about as gentle as it gets. The claw does not touch the hole when it enters, but when it does, it has a ‘soft’ grab before it pulls down. Plastic parts are very durable, especially nylon which is very tough but ‘giving’ and is self-lubricating. Look inside most projectors and you will find loads of nylon parts.
Now, here’s a thing… Just today I started working on a new idea for intermittent frame transport, that does not use a claw, can tolerate broken socket holes, and theoretically can position the frame within 5microns. I have also worked out a method of triggering the capture device directly from the sprocket holes, even if they are damaged, or missing. The whole thing can be 3D printed in about 4 hours. I estimate that for 8mm, the frame rate would be about 3-5 fps, just right for my LifeCamStudio webcam.
When I have demonstrated a working model to myself, I will post details.
Jeff
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We have used a similar cam design in our own scanner designs in the past, we got the idea from the wankel engine utilised in Mazda rotary-engines, like the old RX-7, and it works well.
You absolutely can make fairly gentle pull-down mechanisms, but many film owners will not allow their films to be scanned on anything using one, so it is something to be aware of. All the stuff we have built in the last five years or so has utilised roller-driven, constant velocity systems to avoid the full down, with the exception of the mono sensor equipment, which operates at low-speed and the films are fully inspected and repaired if need be before scanning. Re reliability, yes nylon parts last quite a long time, it was more pointing out to any DIY people that anything you build has to be reliable and accurate over a huge amount of cycles, and wear can cause problems when the targets are as small as sprocket holes and you are running at speed, especially when film may have shrunk from its original spec.
The stuff you are working on sounds great, and it would be wonderful to have something that accurate that works on broken sprockets as well. In the past we have gotten around that by having large diameter wheels so that a missing sprocket or two is automatically corrected by the surrounding sprocket holes being engaged, I’m keen to see better solutions come out of the community.
What is their reasoning behind that? I can appreciate that doing it with a modified projector is a bit questionable, but if the pull-down mechanism is designed to be tolerant of damaged sprocket holes, and uses a gentle motion at low speed, what can be the objection? I think the pull-down method has got to be the most accurate, repeatable, and reliable answer, and makes very few demands on the trigger system and optical capture device. It succeeds because the mechanism that advances the frames is cyclic; in other words the same components are used for each frame advance so, even if they are not perfect, the delta-error between frames will be virtually zero. I refer of course to mechanical systems, but the same cannot be said for those driven by stepper-motors, even if they are judged to be cyclic. This is because they are digital, and are subject to step-resolution problems which, even if they do not accumulate, are hard to correct.
Another thing - with pull-down it is possible to make several captures of each frame, then average them to reduce grain and colour noise generated by the camera’s imaging chip.
In any case, these films must have been through projectors many times before, so what’s the problem?
Jeff
The reason is that some are in a very fragile and very shrunken state, the spacing varies enough on the sprockets that no single mechanism could really cater for it, and it certainly would not run through a projector in the film’s current state.
Some of the film we get is incredibly fragile, you can check out some of our work here:
https://vimeo.com/65801866
Jump to the 35 second mark and you can see what kind of shape the film is sometimes in, and this is just from the early 70s, some of the pre-war stuff we get in is in really bad shape and would not work in any sprocket-based feed system.
There are real advantages to a pull-down based system, the one in the Imagica scanners we also use is very gentle on film, and you can triple flash each frame to get a better dynamic range, as well as capture a damage matte, but some film will just not run through it, or more to the point, the film archive or owner will not allow it to be run in a sprocket or pull-down based scanner.
If the client won’t allow it as a matter of policy, then all the arguments in the world don’t help.
For most people though, a gentle pulldown system will work fine with film in reasonable shape.
I’d really strongly advise that while using webcams is cheap, the dynamic range on even the best ones is really awful, and gets results that are so far below even the $300 cameras with better sensors and better electronics design, that I would only consider using them when working out the kinks in one’s scanning rig.
$295 gets you a true 720P camera with extremely low noise, true 12bit processing, and fast enough to run at 25fps without a struggle. $495 gets you better than HD resolution - In the scheme of things it is cheap, and you get results that genuinely challenge $30,000 scanners in image quality, and save you a ton of time, even on small jobs.
The ability to scan 2 hours worth of film in 2 hours instead of 16 hours at 3fps, and the ability to then capture the soundtrack in real-time during the same pass is a massive timesaver, and the camera cost pays for itself very quickly in better quality, saved time and excellent stability. Plus you are tied to the scanner for less time, you really don’t want to leave film unattended, even in the best scanners.
My opinion is that both approaches have merit. If I’m a home user and on a budget, then the intermittent drive system may be more economical and the time isn’t a factor, especially since I can make my own judgement call regarding the film’s condition and suitability for the intermittent drive. I might be better served by investing in a better light source and a cheaper (slower) camera that does multiple exposures.
If I’m renting out my equipment or doing transfers for profit, then the time savings and quality upgrade might make sense in this scenario, as it would if I know I have poor quality stock that can’t be risked in an intermittent drive system.
All that said, this thread is specifically about the image sensor, and to me, the benefit of Kinograph would be the ability to incorporate many (any?) type of sensor as budget and needs allow. To that end, what would be the difficulty in regards to software and physical design of the machine that would need solved in order to do this?
You could use almost any sensor, the main constraint is the physical size of the sensor and the container it is in. A Canon 6D is a very different size to a PGR Flea or a webcam for instance.
So mounting the sensor will be a different design depending on the sensor chosen, as the mounting and spacing of the sensor really is critical.
The theory is the same though, you need to be able to adjust the camera in multiple axes with quite fine precision to be able to frame and focus the film correctly, so the design would be similar regardless of the sensor, but would vary depending on size and lens choice.
I agree, that for most people, the intermittent design would be the best fit, but it may work out cheaper or less complex to have continuous motion, or it may not. Both need to be pursued.
I did not appreciate that. The films that I am working with, although up to 90 years old, (fortunately none are nitrate based) amazingly, it seems, appear to be in good shape, but there’s no way that I would put them through a projector now. That’s why I have been working on a gentle pull-down mechanism of my own. However, I agree that something working on the lines of the Kinograph would be preferable, but I was initially concerned about the instability of the image framing, and the fact that I did not think I had a suitable optical capture device for continuous film motion.
Over the last few days, I think I have come up with something that may stabilise the frame triggering (I have emailed M about it for his opinion, but too early I guess to get a reply). The main problem then was to look at the digital camera aspect, the technology of which is something I knew least about, mainly because my past photographic experience has been with mechanical still film cameras.
The last few days of research on the subject have been enlightening, and turned up a few facts that surprised me, but answered a lot of questions that have been in my mind for some long time.
For example, I wondered how an image chip could capture a flash image, when the pixels on the chip must take a while to be scanned. I was relating this in my mind to the way a flat-bed scanner works, which was totally wrong. I now know that the image is captured globally as a charge stored in each pixel, Then the whole image chip is scanned and the charges converted to voltages once the shutter is closed. So the whole mechanism is very similar to conventional film cameras. So I then trawled around looking for an imaging camera that I could afford, that had most of the attributes required of telecine, but without a shutter and all the peripheral functions and glitz that goes to make up an expensive DSLR with remote triggering.
I won’t bore you with the details of my journey, but I have finally found something that looks very promising, and for which I have found full technical details of the image chip it contains from its well respected manufacturer. With a wry smile, I can see how the marketing people who sell the camera have taken these details and dressed up their product to appear better than it probably is, but I have taken little notice of that - facts are what interest me. Here is the camera - MC500 <$100
It is advertised as being a microscope eyepiece camera, which put me off at first, but I guess that is one of their strongest markets, together with telescopes.
Before you throw your hands up in horror, download and read this chip spec. Yes, I know its imaging performance does not compare well with a high-end 22MP DSLR, but so what? By all accounts, it should be more than adequate to capture stills from up to 16mm, and at a decent frame rate too, >5fps. If the data sheet is anything to go by, it promises a dynamic range just over 11 stops, which I think I would be happy with. It also has a standard C-Mount lens port, which is a big bonus. There is some confusion however over the pixel resolution, because I think this must include the three colours which brings the real resolution to nearer to 1.7MP. However, there are much more expensive cameras of a similar type out here that have similar real resolutions which quote 1080p performance (see Grasshopper3 from PointGrey the GS3-U3-23S6C-C is the cheapest - $995 ) , so I am not overly concerned.
Anyway, it’s too late - I’ve bought one to quell my curiosity, and it should be here tomorrow. I’ll let you know what I think.
I’ll be keen to see how it performs. With 2.2um pixel size, I would expect its low-light (i.e. shadow areas) to be quite poor, and the noise to be a problem, but I haven’t tested anything from this supplier, so it will be good to see how it goes.
Do you have any calibration slides or SMPTE test film strips to test it with?
If not, it might be worth picking one up from here:
They are made for transparency scanners but are a great test for sensors and are quite affordable.
I’d be interested to see how it performs as well.
You might get a bit less than the quoted frame rate if you are triggering it, and it is a rolling shutter so you’ll either have to flash it or hold the frame still.
Hi Folks,
I just took delivery of the MC500 a few hours ago, and I thought I’d report on my first impressions right out of the box. I have not plugged it in yet, or installed the software - that will have to wait until tomorrow, but I have checked out the construction, and worked my way through the software user manual, and from what I see at the moment, I’m impressed.
For the low price, and the illustration I posted, I was expecting a lightweight plastic housing, with no visible screws, and an insubstantial C-mount. But not a bit of it - the body is all metal, and assembled with camera-quality screws, both countersunk for body parts and hex-socket set screws for locating and adjusting the C-mount. There is also a set of C-mount sliding tubes, again of apparently high-precision metal construction incorporating friction o-rings, presumably intended to interface with standard microscope/telescope eyepieces. These will be ideal to interface with various M42 camera lenses that I have after I have made a suitable adapter on my 3D printer. The sliding aspect will be perfect for adjusting macro-zoom.
I was also expecting just a slim driver file, but there is a pretty comprehensive capture program included as well that seems to have wrapped up the complete functionality of the capture chip, but appears not to have precluded the use of external frame-grabbing software if required.
I cross my fingers that I do not come down to earth when I test its performance tomorrow!
Frame rate does not really concern me as long as it’s above 3fps, and yes, I realise that the lack of global shutter has the the constraints you mention, but most DSLRs are in the same boat, and have to rely on focal-plane shutters to truncate exposure after flash, unless used in very subdued light, which is what I would do if using Kinograph with MC500.
Will report progress very soon
Jeff
It’s taken a couple of days, but I am now able to make my second report on this intriguing sensor. Rather than setting up elaborate resolution assessment experiments, I jumped in feet-first, and cobbled up something to quickly capture a single frame of an 8mm film that was shot over 50 years ago, and which is typical of most of the films in my late father’s collection (shot with a Bolex B8 - the best available in its day). I needed to know if it was worth digging in deeper to put numbers on all aspects of its performance, something that I know could take some time.
Firstly, I had to decided on the optics to use with the sensor. A few experiments showed me that one of my best classic still camera lenses, reversed and used with extension tubes should give the super-macro performance needed for this initial exercise. Then I had to design and make a couple of components to hold everything securely together, yet allow some degree of adjustment. I used my 3D printer to do this. Here is what I came up with, which fits to a vintage Eumig P26 8mm projector which I have used before because of its bare simplicity coupled with superb quality engineering.
I just put a short length of film in the gate, and started playing. Here is one of the results, that was captured at 720p resolution.
It is immediately obvious that the image is ‘soft’ by modern standards, but that is all down to the image on the film, which is typical of all the 8mm stuff I have from that era. There may be a slight performance hit from my optics train, but I see well defined scratches that suggest it is probably not that significant. BTW, I purposely did not clean the film, as I would normally do.
This image has not been processed in any way, except for cropping, and shows how much the colour has drained over the years. So this test does not give much indication of the MC500 colour performance, except to say it looks just like this in an 8mm viewer/editor.
The main thing I wanted to know was its resolution capability. The picture below goes a long way to providing that.
It is an enlargement of the area in the first picture, near the bottom left, of the heads of two old ladies walking by, and includes a small tree branch. It is immediately obvious the resolution of the sensor is several times better than this image needs.
Draw your own conclusions from this, but I am inspired to perform much deeper technical assessments of this sensor not only for telecine, but also for other things I am involved in which normally need a DSLR, mainly for lens interchangeability.
Finally (please don’t laugh!) I’m going to try dispensing with the lens altogether, and use a pinhole approach instead. You never know…
Jeff
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Maybe you should reverse the film, the emulsion side on the other side. The dirt on the image is sharp but also unsharp and I think that is on the other side.
Yes, I tried this originally, but the image focus was not visibly improved. However, the scratches were not so well defined, and I wanted to have something sharp to focus on.