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Old January 12th, 2007, 08:32 AM   #16
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Yeah I know, there already were quite a number of threads on this issue.
I was already talking about the pure adapter light loss.. it's simply more than only 1 stop... and certainly the cinevate is at least 1 stop "brighter" (of course for both models its different when you use another GG).

Or if you want to see another good example of the problems I spoke of have a look at this thread:
http://www.dvinfo.net/conf/showthread.php?t=83013

The barrel distortion while present in every grab is especially unpleasent in the below-85mm-grabs... on the first grab (20mm) it gives me instant headaches (together with the edge unsharpness)...
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Old January 12th, 2007, 08:37 AM   #17
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Well it's definitely SGpro or Brevis then to own... and mini35 to rent for more professional shoots!
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Old January 12th, 2007, 10:04 AM   #18
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Soeren,

Just to be fair to M2 (in regards to the images you make reference to above), I am an EXTREMELY inexperienced user. This was my first attempt at the M2 with the new V1U (which I was also very inexperieced with). I didn't use a focus chart nor did I do any adjustments between lens changes. My total setup was approx. 10 min. Perhaps I shouldn't have 'jumped' to the forums with my results, but my excitement is/was obvious.

It was near sunset, and I used almost every lens wide open. I know of the problems with the 20mm (especially the CA and the edge softness). This isn't to say that their aren't issues with the M2, but to completely dismiss it and to use my sample clips to do so is unfair. Many users have had extremely pleseant results and I'm sure the other 35mm adaptors have their pros/cons too. I'm not making excuses for the M2 but there is a good chance that the quality of the stills that you point out could be more user error as opposed to what the M2 can really do.

Every new tool to our business should require patience and have learning curves. If one 'tool' doesn't work as you wish, we are fortunate that others have made different 'tools' as alternatives.

Again, the stills I posted should not be used as "this is what you will always get". Once I've put the proper time into learning the ins/outs of my system, I'll post more stills and clips; then feel free to critique my images.

Todd
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Old January 12th, 2007, 10:40 AM   #19
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In the 20mm shot, there is a bit of concentric CA evident in the corners top left and top right.

If all the other camcorder zoom and focus settings are correct, this then hints that there might be possibility of improvement if the dioptre lens can be placed closer to the camcorder's own lens.

Another solution might be to use a less powerful dioptre and set the dioptre and camcorder furthur back from the groundglass.

What zoom setting in millimetres do you use to get your image framed? It looks to me like you might be trying to take too much area off the groundglass as there is a slight brightness falloff to the corners and that should not be happening with the M2 groundglass as I know it.

Check with the Redrock people. You may find that their setup is optimised for a groundglass area of 22mm wide. The Mini35 I understand, maybe incorrectly, to be 21mm.

I'm using the same Sigma and I do not get corner falloff with this lens at all. I'm using two size areas off the groundglass, about 26mm with a 4+ dioptre and about 22mm - 24mm with a 7+ dioptre. This is with my own adaptor, not the M2, but the basic rules are similar across some adaptors.

Sacrifice a little of the groundglass area, say about 4mm less width by going in a bit closer with the zoom if you can. You may lose a bit of resolution but you may recover some with sharper focus across the whole of the smaller image.

I also understand that setting up and fine-tuning the M2 takes a bit of effort. If the SLR lens backfocus is off, the wides are not going to focus right. They might even CA in the corners but I don't know about this.

The zoom relay wth in-camera lens type camera is a handy composition tool if you have dark areas or even just plain soft areas on edges of the image.

Centre axis of SLR lens relative to centre axis of camcorder seems to be off to the left by about 1.5mm. (to the right as viewed in the image.)

This could also be caused by a bending force on the camcorder/adaptor junction if you have it set up on a bridgeplate and rods and have tightened the baseplate screw down a bit hard or forced a fit if it has been a bit baulky

Is the dioptre mounted direct to the camera or mounted in the adaptor in such a way that the centre is correct for the camera lens centre.

Also it could be an offset of the centre of the imager relative to the camcorder lens optical centre. This is more common than you might believe and optical steadyshot fluid prisms at rest among other things. Its not a big deal.

A fourth cause could be SLR lens centre axis not being coincident with the camcorder centre axis. Because your image is not conveyed direct to camera from the SLR lens, this is not a big deal.

Don't take much notice of me on the offset comment because it might also just be a naturally darker area in left of the image.
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Old January 12th, 2007, 10:44 AM   #20
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Anyone dare to rank in order of best to worst for all 35mm adapters?

I'd say PS Technik mini35 is at the top. Yeah it eats light, but it's robust, no flip, no tweaking needed and it works everytime - on a steadicam, tripod or shoulder without any external LCD needed or flip tricks.

What's at the bottom of the list... ?

(we'll figure out the middle later)
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Old January 12th, 2007, 11:01 AM   #21
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Dennis.

You have a mischievious nature.

I concur with the Mini35 comment.

Not everybody who has spent their best and only on a turkey and has sung its praises here until they found its wrinkles is unlikely with few exceptions to post a rebuttal.

However as a starter, here is mine. My very first fixed GG adaptor which I named the Pringlecam, (2 x pringles packs, opaque lid for GG, 5-stop light loss, about 200 TV lines of resolution, rolled-up toeless sock in one end to hold the X-Fujinon f1.8 50mm ( a good lens actually ), backfocus rearwards, - finger push, backfofocus forwards, wire hook in sock, another toeless rolled up sock to hold the Pringlecam on front of the camcorder along with some gaffer tape. First modification was letterbox slots in sides of Pringlecam and 600 grit grind on microscope slide for GG. )
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Old January 12th, 2007, 03:18 PM   #22
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Spell "Dennis" backwards and you'll see why we're such a mischevious bunch :-) Dennis H, you're also a fellow Canuck...even worse! We specialize in self-deprecation and potent beer.

Soeren, I would agree...4x4 filters and a mattebox are very, very nice when you're in rails mode.

Dennis H, the Brevis with a 50mm f1.4 attached will see about .5 to .7 stops loss (that's total loss to the camera). That doesn't make sense in a conventional argument on optics and apertures..but adapters are not conventional optics as there is an imaging element involved. Certainly, calculating f stops using plain old subraction is a common mistake out there...done it myself a few times :-) Many users with the CF1 element installed claim "no light loss" which is not the case...they're seeing at least .5 to .7 (calculated properly). There's usually a huge discussion on why this is impossible, but as always, I defer to the users of the device. Cf2 and CF3 see a bit more loss, but not as much as I would have predicted.
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Old January 12th, 2007, 04:08 PM   #23
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Hi Dennis, it's Dennis. :P

You've got me all figured out with the beer thing... had a couple pints last night in fact.

Listen what's the ETA on a brand new fresh off the mill/press Brevis? I got my HVX this week and my mini35 is series 300 so it's for SD only. I've been leaning every which way with a second 35mm adapter to tinker with at home inbetween renting mini35 series 400 for more commercial type work.

I've been leaning towards the SGPro r2 but looks like I missed the February shipments so it would be sometime in March and I can't wait that long. I have no patience. I've even considered the M2 to tinker with for a bit since they're readily available (and can always be sold) but now I'm on the Brevis path to light again (no pun intended).

What's the highest I can stop down before seeing and any GG grain? I typically shoot no lower than f2.8 and no higher than f5.6 and at very rare occasion f8. Are there any online samples of still frame grabs at various f-stops to demonstrate this?

I will likely continue some discussion with you offline via email.. cheers!
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Old January 12th, 2007, 05:17 PM   #24
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Yep, a few jugs of Rickard's Red met their fate at our throats last night too :-) Drop an email and I'll fix you up with the info you're looking for. The Brevis with CF1 is happy (with the appropriate light) at up to f16, however no one looking for max image quality or any kind of DOF typically shoots that high. At f1.2 to f8 you would certainly be OK. CF2 and CF3 are less flexible in terms of very high f stops. I will have comparison footage of CF1, 2, and 3 up soon, at a range of f stops. We just finally got all the CF3 equipment etc in place, something we've been waiting for, to do the test shoots with production versions. There's a few other Torontonians with units, so you're in potentially good shape for a test.
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Old January 12th, 2007, 10:08 PM   #25
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The Mini35 series 300.

What is the HD limitation with this, ie., groundglass too coarse/too small area used/optics. If it is just the groundglass, there might be home-improvement options there.
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Old January 12th, 2007, 10:24 PM   #26
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Quote:
Originally Posted by Bob Hart
The Mini35 series 300.

What is the HD limitation with this, ie.,
I honestly have no idea. I've only ever read that it's the grain from the spinning GG on a series 300 that shows up on HD. (The series 400 has a vibrating GG element not spinning.)

If it's only the GG as you suggest then definitely some home-improvement might be possible. Interesting thought...
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Old January 12th, 2007, 11:03 PM   #27
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The grain should not be visible if it is working right but the ratio of the grain size versus the image size may have been altered to improve resolution to acceptable HD levels.

Two ways this can happen, larger image area on the groundglass or finer grain texture.

If spare spinning disks could be had from P+S for dressing to a finer texture or Wayne's source in the UK could make them with a finer texture than the originals, it would be an interesting hack which might extend the useability of the series 300.

I think P+S may have erred on the cautious side with their GG in the series 300 to eliminate edge fall-off or hotspots. They suggest no tighter than f5.6 for SLR lens aperture but I have seen acceptable images from f11 against a bright sky with a series 400.

This suggests to me that there might be some leeway with the series 300 groundglass to go finer with the texture. If the available image off the groundglass is small and the groundglass texture is already as fine as it can be, then there is not likely to be any available improvement here because the whole optical path would have to be revised.

I assume in all this that the seriess 400 groundglass is indeed a ground glass diffuser and not a wafer cut from a coherent fibre bundle, in which case I would be barking up the wrong tree.

Could be an after-market business opportunity for some skilled enthusiast artisans. Of course, no warranty of satisfactory performance either express or implied once the elves have had their run around inside.

Might also ruin it too.
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Old January 12th, 2007, 11:11 PM   #28
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I think the mini35 uses a full film frame although I have not actually tried to observe this. It is likely the screen grain is course, a spinning GG should not cause the issue under normal circumstances.
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Old January 12th, 2007, 11:36 PM   #29
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Past published info has suggested 21mm corner-to-corner for image size on the groundglass but I have not read up on latest revisions.

Looking at the Series 400, going by the focus mark which appears correct for Nikon, it seems there is no reducing optic to reframe the standard film frame to the smaller 21mm but that is not to say is has not been done this way and the focus mark is simply a user-guide.

They would only have had to make a finer groundglass or go slightly wider on the image off the groundglass to get to HD. I'm coming up to 850 TV lines horizontal res off my own gadget off 22mm wide and it is a lot less finessed than the Mini35.

I think there might be room for improvement on the Series 300. The motor might have to be altered for higher rpm if the so called "vortex from hell" issue with the slower surface speed of the inner area of the spinning disk is the problem for HD.
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Old January 12th, 2007, 11:38 PM   #30
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Bob: not to shed any light on the matter

Not to shed any light on the matter, but I totally concur that with the older model P+S units there was sort of a vortex feeling in certain lighting situations, esp flat monotone fields. It may have been from a combination of GG grain, speed of the spinning disc, and shutter speed. But it was inconsistent (and the mini35 I was using was on rental) so I never figured it out. The 400 series did away with this problem, but God help you if you have any dirt on the diffuser: it would show up as very obvious oscillating circles in your frame (and it's about a half hour job to take apart, clean it, and get it back together--and don't tell the rental house you did it!).

To be honest, fear-of-the-spinning-disc-design is the main reason I am/was leery of the SGpro, but to date I have never seen anything like "the vortex" from it, although I think I've seen it from the M2. (I think Wayne K has a secret formula.) I believe the SGpro must have a finer grained diffuser or higher rotation speed or both. But I haven't had my hands on one yet, so I'm just speculating based on other people's footage.

Maybe Wayne could shed some light?

edit:I hadn't refreshed my browser, so I was responding to the earlier issue of grain (movement) on the 300. But it seems like we were on the same track. FYI the 400 seems to be full frame motion though there may be a little more room to play with than in earlier versions. Is it finer grained? It seems so, and I don't believe it's a much wider surface area. It is definitely not full still-frame FOV. I don't believe it reframes/reduces anything. You just have the smaller diffusion surface area to rephoto (ergo smaller FOV). That's what makes me think it's finer grained.

From my limited experience, adapting the 300 with a finer GG disc and higher speed rotation seems like it could work, but it still wouldn't be full frame (if that matters to you). Will Wayne sell those diffusers without the unit?

Last edited by Jack Davidson; January 13th, 2007 at 12:15 AM.
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