Frank Vine

If you would like me to scan some frames with my adjustable lighting system and want to send me just a short strip, then drop me a PM.

There are 2 basic types of sensor being talked about here, a line scan sensor and a full frame sensor. Each has derivatives in architecture and process technology. A line scan sensor is almost just what it says, a single line of pixels, although in reality some will actually have multiple lines for RGB and for intensity enhancement by having say 9 lines with the total charge being added up to increase sensitivity. Full frame sensors fall into two main types, those with a rolling shutter and those with a global shutter. Although definitely not exclusively, the former shutter type are usually seen on CMOS sensors, the latter on CCD sensors. Obviously with a line scanner, the image and sensor have to move relative to each other to effect the scan and they have to be tightly locked together otherwise there will be some vertical weaving. For telecine, either full frame sensor shutter type can be suitable, but depends on the lighting design and the film advance mechanics. A rolling shutter kicks off exposure on the first line, then a few microseconds later on the second line, etc. The actual starting and stopping of the exposure will vary down the frame, so if the subject moves, image distortion will occur. For example, a rotating fan blade will appear to bend. A stationary frame in a film gate will not have this problem of course, but a continuous transport system will have an uneven exposure problem if used with a rolling shutter camera. My own RGB lighting design uses a constant current through the LEDs during the exposure period. Actual exposure is adjusted by varying the RGB flash lengths in order to get close to full pixel saturation on all three channels so as to utilise the maximum useful dynamic range from the sensor. I use this method because if the current is varied through an LED the light colour frequency changes, making constant colour balanced exposure more difficult. Also it is easier to switch LEDs on and off with a varying period and fixed current than it is to vary the current with fixed period. Downside is that rolling shutter sensors are no good for this type of lighting design. On the plus side for rolling shutter designs are that they are generally cheaper and have faster frame rates. Sorry for the long post, but hope it gives some food for thought about how you want to achieve the lighting system and film transport and how this will link with the sensor type.

About £1300 in the UK plus tax. It is a bit cheaper in the US if you can source from there.

Hi Sean, If you can stretch to it, then the Point Grey Grasshopper 2 Firewire camera probably has the best performance/value trade-off for telecine....but depends on what you intend to scan from and your intended display platform. It has a few hiccups, but they can be worked around. The biggest is the internal gamma correction is flawed, so need to use 16 bit output mode and apply gamma on the fly in the host if wanting to save to 8 bit avi, or just save as 16 bit and do all the work in post. It will do 26 to 27fps in external trigger mode at 16bit output. Not much else around with that sensor without a big hike in price. There are cheaper and higher res sensors, but these have smaller pixels and hence less dynamic range capability. On the lighting front, flashed makes sense as the exposure times are quite short compared to frame period times, so significantly less power required and no waste heat to get rid of. I have gone a stage further with my RGB system where I independently alter the duration of the R, G and B pulses per frame to adjust colour balance. My latest design has exposure times in the 10's of microseconds with the lens at f5.6, 16mm film and the Sony ICX285 sensor. The flashing means I'm generating the equivalent of a 300W of LED light, but still able to power it from a USB port at 30fps ;) Frank

IMI are an actual manufacturer and I believe often OEM to other brands, like Unibrain. Point Grey and Basler are a couple of other good quality brands to consider. I would not get too hung up about about resolution...if you truly want 1920x1080 original pixel data then you will need a sensor in the order of 3840x2160 plus allowance for cropping, because the bayer pattern on a single colour CCD only gives a true resolution of half area for green and quarter area each for red and blue. Ok, I'm being a bit pedantic, as a good debayer algorithm will make up a bit, so you will probably get an effective resolution of about 75% of the quoted sensor resolution. There's also only so much information you will get out of an S8 frame and at the risk of starting yet another useless debate on the subject, HD1 (1280x960) if cropped is probably about it. A 1920x1080 with side borders to maintain the original format is also about right. Take a look at the wedding image on the Results page of my website ( http://www.cine2digits.co.uk ). Click on the image to download a full res version of it. It is 16 bit straight from the camera (only 12bit of actual data) with no tweaking at all. Try up-res'ing it to 1920 width in Photoshop or the like and see what you think. The big problem with higher resolution sensors is in order to get all the pixels in, they have to either make the silicon huge or the pixels smaller. The former makes it a very expensive sensor, the later kills the sensitivity and dynamic range....so unless you want to spend the rest of your life doing HDR transfers, best not to go down in pixel size ;) Frank

Hi Jean-Louis, Well that prompts the question: what quality level are you looking for? Without doubt, Fred's results are plenty good enough for most people and for displaying on a TV set. They only start to fall down with close inspection at high resolutions and dark level details with contrasty films. Tricky one to answer! The usual rule of increasing quality costs increasing amounts of money applies, but usually the former goes up linearly and the later to a log law! You need to decide which parameters are important for you: like film format size(s) to be scanned, purpose of the scan (archive, show on TV in SD or HD), speed of scanning, how much money you are prepared to outlay, etc. For me, it is as much a technical challenge to get the best out of the equipment I was prepared to buy. My IMI cost around US$2500 but fortunately the exchange rate to the UK£ at the time was significantly more favourable than it is now! There are many other options in between the TIS priced models and my IMI, so "pays your money, takes your choice" ;) Some tips: Resolution is not as important as pixel size as the biggest challenge in film transfer is dynamic range. For example, if you want HD1 from S8, then 1388x1024 2/3" CCD will do the job nicely enough. Most machine camera manufacturers other than TIS usually have have a better set of in-camera features, but build quality can vary...even with the same manufacturer. For example, the Han and Rhein series of models from IMI would appear to be technically the same (on a sensor type basis) but the more compact design of the Han model causes it to have a much worse dark field performance due to internal electrical interference (clock noise I think). Sorry, I've rambled on a bit here and not given you a clear answer...think you need to answer some of the basic questions regarding your own requirements first! Frank

Hi Jean-Louis, Ok, you mean their One4all CMOS cameras...I think it will be good for what it was designed for...a security camera ;) Probably no real use for good quality film transfer, but I haven’t got one to try, so can only comment from CCD camera experience and the data published for the camera and sensor If one could get access to the raw 10 bit data out of the sensor A/D, it might be possible to get something reasonable out of it, perhaps using binning to make up for the tiny pixel size. But as always with Imaging Source IMHO, they go too far with cost cutting and the biggest problem is not having a LUT, or at least some gamma adjustment, available before reduction to 8 bit output. It is also CMOS (most wisdom says not as good as CCD for dynamic range) and a rolling shutter. Rolling shutter is ok for static frame capture, but no use for a continuous motion capture or for RGB light balance adjustment by changing the relative colour exposures. Frank

Sorry, but what do you mean by "All-in-one"? I don't see anything as such on their website. In general, Imaging Source cameras are built down to a price. They are good value (Fred is using one at the moment) but have a few serious weaknesses for Telecine, like no gamma correction before conversion to 8 bit output for example. Frank

PS: Light balancing with RGB LEDs also helps with negative transfer :)

Not talking about separate RGB exposures (although this is an option for use with mono cameras) but an RGB adjustable light source which significantly helps optimise the exposure on a CCD colour camera. If you set all camera colour balance controls to mid way then look at a so-called white LED, it will look significantly green to the camera. This surprised me a bit seeing as they mostly use Blue LEDs, but clearly the phosphor coating has the dominant effect. So if we do not somehow filter the light then compensation has to be made in the camera (or worse still, in post) by amplifying the red and blue…which means amplifying the noise too. This can easily be 6dB (often more) and hence loses about one stop of useful information in the blue and red dark areas as well as adding noise in the bright areas, such as in blue sky areas. So the basic principle is to adjust the RGB light source for close to max exposures during capture, which will give very good white balance if there is any white in the image, then this gives the best source for further colour correction in post. Using this method together with a CCD sensor with good sized pixels (like 6.47um for the Sony ICX285 sensor) minimizes the need for HDR and only requires two exposures if HDR is required. Another (more expensive) way to achieve optimum capture is to use a 3-CCD camera with separate control over the R,G & B exposures. I only know of one make which offers this facility, but it falls down in other areas so is not quite suitable IMHO. Frank

Hi there, As Fred has kind of introduced me, thought I'd sign up....might save a few more direct emails asking me the same questions over again - although it of course it is always nice to hear from other diy'ers and I try to help when I can. My project site is not fully up to date at the moment as I'm working on a new high-power, high-speed RGB flash system for continuous motion transfer - exposures in the order of just 10 to 40us. My prototype is now achieving around 15us at f5.6 for full CCD exposure with an empty gate whilst maintaining a pretty good purity and evenness across a 16mm frame. As usual Fred, you do manage to get more out of your camera than your should get by rights ;) but details in the dark areas are perhaps the weakest area. I'm waiting for you to buy that 2/3" IMI or similar :) Frank