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Silicon Imaging SI-2K
2/3" 1080p IT-integrated 10-bit digital cinema w/direct-to-disk recording.


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Old August 9th, 2011, 10:55 AM   #16
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Re: Really large format SI 2k

Yeah, I've been looking into groundglass ideas. I found a company that sells multiple versions of GG for different cameras at a price that I like. So, I might get one to test with my hv30 and then see about getting one for the 5D. Both would be cheaper than using the photo backing for Canon DSLR cams.
Any suggestions???
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Old August 9th, 2011, 01:25 PM   #17
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Re: Really large format SI 2k

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Originally Posted by River Lopez View Post
Yeah, I've been looking into groundglass ideas. I found a company that sells multiple versions of GG for different cameras at a price that I like. So, I might get one to test with my hv30 and then see about getting one for the 5D. Both would be cheaper than using the photo backing for Canon DSLR cams.
Any suggestions???
No need to use a ground glass adapter with a 5d (the whole point of a 35mm adapter was to allow the use of slr lenses to achieve narrow depth of field - you already have this function with a 5d).

Just to confirm; you are aware that there were are a large number of companies that made 35mm adapters (with spinning/vibrating/static ground glass screens) suitable for the HV30? A good number of them are available secondhand these days at cheap prices.
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Old August 9th, 2011, 01:39 PM   #18
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Re: Really large format SI 2k

Simon.

I think he is specifically after the Coatwolf "look".
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Old August 9th, 2011, 01:44 PM   #19
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Re: Really large format SI 2k

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Simon.

I think he is specifically after the Coatwolf "look".
Oh, OK. Well let us know how it turns out River; should be an interesting project!
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Old August 9th, 2011, 02:05 PM   #20
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Re: Really large format SI 2k

Simon.

I think he is specifically after the Coatwolf "look".


River.

Whatever groundglass you use will suit both cameras. It is the lens you use on the 5D and the zoom setting you use on the HV30 plus how close either can focus which will determine how well each works, not the groundglasses. Be aware that your image on the groundglass screen will be upside-down. With the SI2K camera head, it looks like they mounted it upside down to flip the image. The software also has a flip option for the preview screen. This inverted image was a problem with the non-flip home-made 35mm adaptors before people started building surface-coated mirror or prism flip paths. For the Coatwolf rig, a flip path would be difficult and bulky. It would also have to be surface coated mirrors as the prisms would have to be huge, heavy and would be vulnerable to damage.

So it is likely your cameras would have to be mounted upside down to the rig or you would need a monitor screen which could either flip its image or operate upside-down itself so you can see the image upright.

If your cameras cannot focus close enough onto the groundglass you might need to use a macro-spacer on your Canon 5D mount to place the lens slighly furthur forward or buy an achromatic dioptre ( close-up attachment ). Don't buy the cheap single element close-up lenses except for concept testing as their colour rendition and sharpness is dreadful. For the Coatwolf I expect you would need no more powerful a close-up lens than a 2+ or 3+ with an approx 8"-10" setback with your HV30 camera lens zoom on about 15mm-20mm. With your 5D, a 28mm or 35mm prime might do it. These are only wild guesses on my part. 8" to 10" may seem a long setback but you really don't want to get any closer as brightness falloff on the corners of the groundglass image might become a problem.

Coatwolf might have also included a large plano-convex condensor lens in their design. The smaller 35mm adaptors use a form of condensor, lens to deal with brightness falloff, either a fresnel (Cinevate) or plano-convex element (Letus). The power of the condensor has to be a match with the other optics and distances between otherwise it does not work properly. Going by the bridghtness falloff on their wide shots, I don't think they have used a condensor but who knows. If they did, the element might have come from an epidioscope or an old overhead projector. It might also explain the hard vignette on some of their shots.

As I said earlier, this is wild guesswork on my part and might cause that team a little amusement if they happen to read this response.

Last edited by Bob Hart; August 9th, 2011 at 02:08 PM. Reason: error
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Old August 9th, 2011, 02:10 PM   #21
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Re: Really large format SI 2k

Well, yes and no. I did find the film a bit harsh to watch. I walked out with a bit of a headache which reminded me of what happens when you tilt your head slightly while watching a 3d film. But, I did like the vintage feel and the color effect that was created. I'd like to try it out and see what control you can get out of it. Also see how far you can push it.
I did learn how to do video by being a film maker. I miss the look and feel that I got from film but, it's cost effective to shoot digitally these days. I never liked the look of digital video but, I have enjoyed dslr cameras because it doesn't look like typical video.
If you have some names of the companies or suggestions on where I can save a penny on finding gear, I'm all ears. The GG that I found for the hv30 will be about $65.
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Old August 9th, 2011, 07:33 PM   #22
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Re: Really large format SI 2k

Thanks BH, that's pretty much how I guessed it would work.
I guess the GG I'm looking at attaches to the lens of the camera. So, I thought that it would be different for the hv30 compared to the 5D. I'll have to do more research.
I thought they had the SI-2k upside-down but, I haven't had any hands on with that equipment and was guessing. They did have a monitor and then they ended up using the laptop. I would like to have less wires attached to my rig but, then again I'm not friendly with SI so, I don't forsee having to work with that camera.
In good news I did get an email from FedEx and the camera is on it's way. I will need to figure out a camera rig to hold everything together and the GG.
Oh I'm looking at JetSetModels.info. The vibrating GG cost about $65 and there are different ones for different cameras.
Thanks again guys.

Best wishes.


EDIT:
Research results:
Thinking if I go the hv30 route to make a follow focus to control the GG by JetSetModel. Found these 6 gear rings 55-65mm for follow focus on ebay:
http://cgi.ebay.com/Set-6-gear-rings...ht_3428wt_1126
also on this site:
http://www.dvcity.com/dvshop/A-set-o...s-0.8-mod.html
I could look into getting something like this L-box attach a gear to one end and a Follow focus knob (need to find a knob) on the other end.
http://www.huco.com/products.asp?cat=162

I did some searching on Amazon and am building a cart for follow focus parts.
This is a gear that should work with the gear rings, I found a set of cheaper gears that I'm buying.
http://www.amazon.com/Genus-GL-G-PG08-Follow-Systems/dp/B003XU7BZ6/ref=sr_1_1?ie=UTF8&qid=1312938184&sr=8-1
Anyone know a good place to get 15mm rails to build my rig for this thing? I fugure I'll need to mount the 4x5 camera and then the hv30 in the back going to the GG. Probably some spacers and things to keep the dirt out. So, any suggestions?

Last edited by River Lopez; August 9th, 2011 at 08:25 PM. Reason: Added search results
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Old August 10th, 2011, 12:19 AM   #23
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Re: Really large format SI 2k

Here's some links to a look around inside a few 35mm adaptors to give you a hint of what you are in for.





A spinning groundlgass in something the size of the Coatwolf is going to be huge. It is also going to be hard to balance. The Coatwolf evidently had a problem as there is a vibration of the image in the wide shot in the trailer.

I don't think you are going to be able to get a satisfactory movement with a vibrating design in something the size of the plate-camera screen. Whatever you make will rattle the heck out of any camera you attach it to unless the rest of the enclosure assembly directly around the groundglass is very heavy.

The vibrating mechanism in the Letus and Brevis adaptors is passive with eccentrics on micromotors attached directly to the groundglass screen carrier frame. In the P+S Technik Mini35-400 and Pro35, the mechanism is active with the groundglass moved by three short halfcranks driven by a common drive belt.

If you are going to try to move your larger groundglass by the simple vibrating method, there are some things you need to design in which are less critical on the smaller adaptors.

The carrier frame for your groundglass will need to be rigid enough to avoid flexing. You can stress the glass itself to save some weight because weight in these things is your enemy. However, any bending stress introduced may break the glass.

To avoid that bending stress, the spinning eccentric on the motor must be exactly in line with the mass of the groundglass. The mass of the electric motor as it is moved by the eccenrtic mass will introduce a bending stress. The carrier around the groundlgass that you hang the motor off must be strong enough that the bending is not transferred to the glass.

The tendency of any passive vibrating movement is to rock the groundglass rather than actuate it in a circular motion.

The movement pattern is a grain of rice or elliptiod shape with the movement closest to the motor being larger and in one direction and the movement at the opposite end being smaller and rotated 90 degrees.

If the groundglass is too heavy for the eccentric, then there will be a motionless spot within the groundglass itself and the movement of the edge opposite the motor will be 180 degrees out of phase.

To achieve the best movement pattern with consistency across the entire groundglass surface, you likely will need to add an equal mass to the groundglass carrier frame outboard of the motor shaft centre.

Because of space and construction convenience an identical mass is not practical, therefore a smaller heavy mass closer to the motor shaft centre will be needed. That itself introduces a need for more weight in the eccentric and more motor power to drive it, a bit of a Catch 22.

Fortunately, you need only to be able to move the entire groundglass about 20 microns at the narrowest point of the elliptoid pattern to deresolve the 5 micron groundglass texture adequately. So an opposing mass need not be equal. None of the builders of the 35mm passive motion vibrating adaptors needed to bother as it turned out.

No vibrating groundglass arrangement will work satisfactorily for camera shutters faster than approx 1/100th second. A fixed pattern artifact will become apparent with lens iris settings of f5.6 or tighter.

The sprung pillared support methods used by Quyen Le in his Letus design and Dennis Woods in his Cinevate adaptor and I think also Wayne Kinney with his SGBlade design, are the proven system. Don't use too many as they also become part of the resistive mass. Three pillars seems best.

Gravity will also have some effect on your vibrating movement. A steep camera tilt up or down will alter the pattern slightly. If a motor will not start due to a low battery, pointing the camera directly up or down may get it started a few more times, as gravity force upon the eccentric at rest does not have to be overcome.

There. Some info for you that may not be of a lot of use but setting out some of the dead-ends you may run into.

Last edited by Bob Hart; August 10th, 2011 at 01:04 AM. Reason: added text
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Old August 10th, 2011, 06:30 AM   #24
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Re: Really large format SI 2k

Other than tilt shift, is there an advantage to this system?
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Old August 10th, 2011, 07:45 AM   #25
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Re: Really large format SI 2k

On a low budget and assuming you do not want to shoot with digital SLR cameras, the large format groundglass has potential to give you the sharpest rendition of any groundglass image relay system to a high defintion 2/3" video camera sensor. The best performing 35mm groundglass adaptors can achieve the practical resolution of 1920x1080 and 2048x1156 video sensors.

How sharp large format can be will depend on how sharp the lens system on front is and how sharp is any lens which is added between the groundglass and the video camera.

This potential may be offset by a limited choice in fast lenses for the large format if there are any to be had at all.

Achieving consistent sharpness with groundlgass relay requires exceptional diligence by the camera operator.

Lesser convenience of operation may work against a low budget production which is on a tight schedule.

Whatever might or might have have been the Coatwolf team's original purpose in building the camera, it seems the signature "look" it has provided to their project is the selling point for using it.

For more practical use and a faster pace of consistent high quality work, a conventional and uncomplicated system makes more sense.

Last edited by Bob Hart; August 10th, 2011 at 07:55 AM. Reason: error
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Old August 10th, 2011, 10:53 AM   #26
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Re: Really large format SI 2k

For me it's the look. I have always liked the look of film over digital any day. When I saw the films se7en in the theaters it was grainy, dirty and dark. It really created a look and style for the film but, with DVD and Bluray they removed the grain and left it clean. Just doesn't hold up like the film did.
Bellflower had a wonderful look, which is the films style. It didn't quite look like if you filmed a projected image off a screen but, not too far off. There were parts where you could just see the dirt that got into the camera and sat on one of the lenses and it just added to the feel of the movie. (side note: I do think that this will be for certain projects and shouldn't replace digital cameras.)

Things I did notice with Bellflower and the Coatwolf were that they did have issues with the focus. Parts were soft and other parts the camera person was hunting for a focus while a scene was playing. Things like that distracted me from the film.
As for their groundglass it does seem that they have some huge metal thing in the center of the two cameras. I was thinking that this could be some sort of old film camera that they used for the motor or something. Figured that's what the AA batteries were for.
I want to see what the alternatives are with the set up and see if I can get a similar look with less of the headache. I don't need to recreate what they have but, if that's what I'd have to do to get the film to look like I want it to then I'll have to do that.
And thank you for the advice. It is very much appreciated.
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Old August 10th, 2011, 11:26 PM   #27
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Re: Really large format SI 2k

That groundglass enclosure has been bugging me for a while. I think I have seen it on something somewhere.

Those guys mackled stuff together from scrap. Off the top of my head, the nearest thing I can imagine is a cut-off from the very front section of the camshaft cover on a single-overhead-cam engine like an old Mercedes or Toyota Cressida. The only other thing I can think of is the shutter enclosure and disk assembly from an old motion picture projector with the shutter disk replaced by a plastic groundglass disk. This would have provided them with pretty much all that they would have needed. A small electric motor to belt-drive it via its existing pulley would have done the job.

I think I might be giving them too much credit or over-engineering their invention in my imagination. On the surface, the enclosure looks like it could be part of a machined base frypan with plywood siliconed to it to provide the rear cover and another piece on front to mount it to. That would add to the intrigue of their device.

Their Mark One appears that it might have been a fixed groundglass arrangement.

Focus-hunting. That is the signature of 35mm groundglass work when focus pullers and marks are not used. Agile work is not impossible but is difficult unless you have lots of practice under your belt already.

With large format, its even shallower depth-of-field for given fields-of-view, plus the f5.6 iris limit, it would be a bigger challenge.

Last edited by Bob Hart; August 10th, 2011 at 11:50 PM. Reason: error
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Old August 11th, 2011, 11:04 AM   #28
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Re: Really large format SI 2k

Well, they do have a welder in the films so maybe they did weld some frying pans together. The weld is pretty thick so, I thought it was something they put together. I'd like to see if I could do something smaller and lighter so, I won't need to figure out how to weld some pans.
The groundglass will most likely stay a secret unless someone does finally get to film/photograph more than they are showing.
And I know that they used the Model 1 for a lot of the night shooting. In an interview I read they talked about using that for the night shoots and then doing color correcting to make that match the footage shot with the model 2. I think that I'll end up with something at first that looks like model 1 and then if I don't like how it looks I'll play around until I get my own frankenstein.
Any one know a good place in the US to get 15mm bars? I think I'll have to build my own rig to hold this monster.

Last edited by River Lopez; August 11th, 2011 at 01:05 PM. Reason: Thick not think
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Old August 11th, 2011, 12:06 PM   #29
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Re: Really large format SI 2k

Dennis at Cinevate, adapterplace.com (Letus) or letusdirect.com ( their vendor ), or Wayne Kinney (SGPro), Zacuto, do rods and bridgeplate kits. Zacuto had their own Letus specific kit but it may have been discontinued by now since the DSLR coup.

The Indian vendors, cinecity etc., also do kits. These are cheaper but you get what you pay for and you need to be dead sure what you are asking for. Their tubes are hollow, may be very slightly undersize and may flex a bit too much for your purposes. Their service for me ( cinecity ) has been good and prompt.

The plate cameras are already built on round rods as part of their construction method. You might just have enough hardware to play with anyway.

I have it on good authority that the SI2K camera head they used was a protoype assembly which explains the different look of the casework.

Wayne Kinney (SGPro and SGBlade) and the Redrock people used spinning disks on their first adaptors. Wayne had a supplier in the UK who made up plastic disks for him. You could make your own up with Lexan or perspex and have them turned and hub bored to near-balance on a lathe by a machine shop before you grind a groundlgass texture onto one face. You need 5 micron grade alumium oxide powder abrasive for the right grade of groundglass finish. You could finish in 3 micron but there will be a little too much transparency and you then encounter a ghosting effect on highlights, which is not cool. The upside is a little more sharpness and better light transmission. Opacity and transparency are trade-offs. Your aluminium oxide needs to be in a water slurry on a very clean smooth dressing surface. a sheet of glass is fine, otherwise another piece of perspex or lexan. You should prefinish this dressing surface with a groundglass texture otherwise you may find the disk will cling from the start and then get scratched.

You will need to file a small chamfer on the front outer edge corner of the disk face you are dressing also the inner hole for the spindle hub. If the disk sticks to your grinding surface it will make it easier to get off. A high pressure water jet directed onto the centre hole might even shift it. You will lose your slurry though.

The plastics tend to self-polish and are harder to achieve a uniform finish on. Your lexan or perspex should be mounted onto a flat panel that you use to hold onto. This is to keep your fingers from leaving gritty marks on the shiny side of your disk. If you handhold the bare disks to dress them local overpressures from bending under your fingertips will cause patchy differences in the texture which will cause flicker. I mounted my glass disks onto metal platens with beeswax which has a low melting point and boiled them off afterwards. Lexan being a plastic may have a shape memory and may warp if you boil it.

Because Lexan and perspex may have a paper backing, you might get away with gluing the remaining papered side to a flat thick plywood sheet as long as it has been accurately machined flat. Any dips or high spots causedd by an uneven mouinting surface will cause varying densities in the groundglass texture and thinner sections around the disk which will cause a barely noticable but possibly annoying rhythmic swing or warping of the image as the disk turns due to a lensing effect. this will be most apparent on wide shots with pinpoints or lines of light in the shot.

Seal the edge with water cleanable bathroom sealer or hotglue so there is no leakunder to dislodge the paper. Give it a few days to set properly. Don't use silcone (acrid smelly stuff) based sealer as it is impossible to get off and will also spoil your slurry. Whilst you grind your disk, don't use lots of pressure otherwise there may be grit entrained into the plastic. Use lots of short circles, lots of time and let the abrasive in the water do its work. Don't let the slurry become claggy and almost dry as this will damage the finish in localised patches which will cause flicker. You will find that if you allow the slurry to become too tired the disk will cling and you will have a devil of a job getting it off. Some particles in the slurry will become fixed and your disk passing over them will be scratched with lines instead of pits being cut into it by rolling particles of grit.

As for a disk enclosure, I made my AGUS35s from PVC sewer pipe and pipe endcaps. They were oversize for the CDROM disk size I used. You might find a larger diameter PVC sewer pipe to suit the large format frame size. You likely will not be scanning the full size of the available image from the lens as there will inevitably be a brightness falloff you will want to crop inside of. A more realistic frame size on the groundglass will probably be closer to 3" x 2" to get inside of the hotspot you likely will discover, especially with wide-angle lenses.

Last edited by Bob Hart; August 11th, 2011 at 12:58 PM. Reason: error
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Old August 16th, 2011, 02:57 PM   #30
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Re: Really large format SI 2k

OK so, my 4x5 camera just arrived. It's beautiful.
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