Which adaptor to pick?

[Ben Winter]

I stand by the Brevis, until another manufacturer comes up with a switchable diffuser screen option.

[Jon Wolding]

Originally Posted by Ben Winter

I stand by the Brevis, until another manufacturer comes up with a switchable diffuser screen option.

Ditto.

Cinevate has come up with at least 6 different imaging elements in the last year... each addresses different cameras, specific looks, low light, wide lenses, etc. If you can afford fast lenses, you can typically stop down to f8 and not see grain (at least, that's the case with my HVX200). The modular approach will also be very convenient when the Cinevate flip adapter is released.

I think the Brevis is the best adapter for tweakers who like to customize and change their setup.

[Bob Hart]

I would like to see Dennis try a smoky filter (one which does not actually) degrade sharpness) in front of his achromatic dioptre. Forgive "smoky". I don't know the correct name.

ARRI apparently made one such for film work which replicates the effect of pre-fogging film for low light, high contrast environments. Sort of works like black stretch if my understanding is correct.

Currently a few people I know use actual smoke but if one does not want the actual whirls and drifts as an atmospheric effect, then it has to be stirred up into the air well and maintaining the density, shot-for-shot is an imprecise dark art. Probably does not do the airways much good long term either.

[Steve Witt]

Originally Posted by Ben Winter

I stand by the Brevis, until another manufacturer comes up with a switchable diffuser screen option.

What other manufacturer is planning on making changable/switchable diffusers? I haven't heard about that.

[Ben Winter]

Originally Posted by Bob Hart

I would like to see Dennis try a smoky filter (one which does not actually) degrade sharpness) in front of his achromatic dioptre. Forgive "smoky". I don't know the correct name.

ARRI apparently made one such for film work which replicates the effect of pre-fogging film for low light, high contrast environments. Sort of works like black stretch if my understanding is correct.

Currently a few people I know use actual smoke but if one does not want the actual whirls and drifts as an atmospheric effect, then it has to be stirred up into the air well and maintaining the density, shot-for-shot is an imprecise dark art. Probably does not do the airways much good long term either.

You're talking about a low-contrast filter. I posted some footage with the Brevis and a 5 power Tiffen low contrast filter a while back, I apologize as I do not remember the URL nor am I in a situation to search for it. It looked good but needs a bunch of levels adjustment in post.

What other manufacturer is planning on making changable/switchable diffusers? I haven't heard about that.

Exactly. That's why I'm with the Brevis until another manufacturer comes along and offers the same option. Not even the Mini35 does that; frankly I think P+S has been completely outpaced and all the footage I've seen with their equipment has been subpar in terms of image quality (compared to a lot of the options available now). The only reasons this hasn't been brought up much is because all shoots that have been done with it are high budget and have higher res cams and a real lighting budget--how can you badmouth footage like that?

[Bob Hart]

Actually, you can swap out the diffusion screen on a P+S and the method is even published on an internal service document for PRO35 operators for using the PRO35 in aerial image mode.

However, it is a hassle and P+S do not encourage the practice becuse of the likelyhood of introducing airbourne contaminants to the optics.

My comment is also a little academic in that P+S Technik do not offer alternative screens.

I am not sure why they went with their particular design except that it is as compact as can be practically achieved around a diffuser which will confer the standard motion picture frame which the P+S remains faithful to. The three-point motion anchoring they use is tight around the groundglass and its supporting rims so there is not a lot of wriggleroom to add area such as by using a rectangular frame without out a major redesign and tooling up for it

Their design also uses a round groundglass in a moving frame. Again I do not know why except that their engineering facilty (or outsourced component suppliers if applicable) may operate equipment for making lenses and the metal collars, rims etc., for them.

Against the parameter of the standard movie frame, you may find other adaptors, not all, may develop issues relating to sharpness.

[John Papadopoulos]

Sorry, I have a few questions:)

Is there any way to compare the dof adapters objectively? Or is there a problem with matching with the camera that could produce different results depending on the model? Is there an ideal specification for each adapter? I mean the imaging parameters and requirements.

[Bob Hart]

For what it is worth, here is a link to a test chart I shot on a JVC GY-HD100/Mini35 whilst setting backfocus for the owner last year. The taking lens was a Nikon f1.8 85mm.

Lighting source was natural summer daylight 2pm and I shot it slightly over which is not a fair test.

The "B" block of the Lemac chart represents 864 TV lines or better resolution.

The "G" block represents 486 TV lines or better of vertical resolution.


http://www.filefactory.com/file/df690e/

The file is a .bmp so may take a while to come back down the drain.

FOOTNOTE: If you can get the wretched thing to download "AND" display, you are a better man than I Gungadin. There is a bit of a convoluted thing you have to do to download. Just click on the green buttons on each page. Download and save and look at the .bmp file separately and it should work.

[Ryan Avery]

Originally Posted by Ben Winter

You're talking about a low-contrast filter. I posted some footage with the Brevis and a 5 power Tiffen low contrast filter a while back, I apologize as I do not remember the URL nor am I in a situation to search for it. It looked good but needs a bunch of levels adjustment in post.

We manufacture our Schneider Low Con filter that is very effective at reducing contrast and creating the desired effect. The issue with most Low Con filters (except ours) is that they lower resolution and create flares in highlights. The water white Schott glass we use tests to over 300 line pairs per millimeter and doesn't flair highlights like similar competitive filters. Check it out if you want to go this route.

http://www.schneideroptics.com/ecomm...=1155&IID=4081

Ryan Avery
Schneider Optics

[Bob Hart]

Ryan.

Out of curiosity, has Century or Schneider contemplated doing a prosumer "back of lens" anamorphic for Nikon and Canon.

There's an up and coming young director over here who crops everything shot on the Mini35/JVC GY-HD100 to a cinemascope frame and it looks good. He also uses the "lost" image top and bottom to enable corrections to composition in post by panning and scanning vertically to reframe.

http://www.youtube.com/watch?v=yoT_Q-7bM6o

My imagining is that there would be potentially a slight resolution gain if an anamorphic adaptor was used because the groundglass grain and diffusion softness would itself become optically compressed in the vertical plane.

This is the one significant area of resolution loss in interlace to progressive conversion and such a gadget might make a few interlaced shooters happy. The progessive horse might also have bolted by the time an R&D effort delivers a viable product into the market.

Trying to squeeze ultra-wide stills lenses would probably be a nightmare but the less extreme range 28mm to 85mm might work.

Just a thought.

[Dennis Wood]

Kind words here gentlemen...thanks.

Ryan, I get a kick out the phrase, "doesn't flare highlights" :-) It's something we've worked very hard on as I couldn't stand halation on specular highlights during focus racks. Nice to see someone else out there feels the same.

Bob, we feel that there's so much room for development yet in the adapter imaging area, that our R&D efforts will continue to push the envelope in that area first. The Brevis system in "flip" mode is a major step forward for the system's optical performance, but the R&D program is still churning forward in the area of our imaging elements. Until it looks "exactly" like film, the program will not cease..and making sure existing users can take advantage will remain priority.

[Loren Simons]

Has no one mentioned the redrock? I don't have one but was planing on buying one in a few days actually, no one like that then? i too would be using an eos lens on my canon a1.

[Bob Hart]

Dennis

Here's a cheeky suggestion which might get me in trouble with Tino at pstechnik.de --- but --- maybe --- offer a retrofit kit of all your alternative diffuser grades for the Mini35, of course with the disclaimer, owner accepts all risks. - just joking.

If there is ever a MINI35-500, no prizes for guessing what options may be included, maybe swappable GG, maybe larger area GG.

The Mini35 "Compact" is a hint that alternative adaptors are drawing P+S into a competitive form of defence as a response in turn, to camcorder manufacturers providing the in-camera flip options which suit the non-flip alternative adaptors.

P+S have apparently done a lot of R&D to arrive at what they have determined as the optimum groundglass grade for their application of the principle.

What I am looking forward to beside all this is the latest itteration of the "smart filter", being R&Dd right here in W.A. They moved away from a pass-through to a reflective process due to some technical issues which the reflective model solves.

I hope they resume R&D on the pass-through method as this could be implemented into a moving groundglass system pretty much as they have it developed if the filter was made 24mm x 18mm and became part of the moving component. Up to 12 stops of latitude, wouldn't you love it? -- and the horses may be wished for by this beggar too.

Regards for the New Year.

[Ryan Avery]

Originally Posted by Bob Hart

Ryan.

Out of curiosity, has Century or Schneider contemplated doing a prosumer "back of lens" anamorphic for Nikon and Canon.

There's an up and coming young director over here who crops everything shot on the Mini35/JVC GY-HD100 to a cinemascope frame and it looks good. He also uses the "lost" image top and bottom to enable corrections to composition in post by panning and scanning vertically to reframe.

http://www.youtube.com/watch?v=yoT_Q-7bM6o

My imagining is that there would be potentially a slight resolution gain if an anamorphic adaptor was used because the groundglass grain and diffusion softness would itself become optically compressed in the vertical plane.

This is the one significant area of resolution loss in interlace to progressive conversion and such a gadget might make a few interlaced shooters happy. The progessive horse might also have bolted by the time an R&D effort delivers a viable product into the market.

Trying to squeeze ultra-wide stills lenses would probably be a nightmare but the less extreme range 28mm to 85mm might work.

Just a thought.

Thanks for the input. I shot this over to my engineers just for the fun of it. Let's see what they say.

Ryan Avery
Schneider Optics

[Bob Hart]

Ryan.

Something I forgot in my speculations about a "back of lens" anamorphic is the variety of of groundglass frame areas different adaptors use, some go for 24mm x 18mm, the motion picture frame, others aquire off the 35mm x 24mm still image frame and others anywhere in between.

The larger format adaptors tend to add optical elements such as condensers, usually plano-convex though there is a bi-convex example out there. This is to deal with brightness falloff issues discussed below.

A condenser between the SLR lens and groundglass is obviously going to introduce an uncontrollable complication. I think most including the P+S Technik products go straight from SLR lens to groundglass via a dust shield. The Movietubes however place a plano-convex element each side of the groundglass which in their case, is a wax layer directly between the two plane surfaces of the plano-convex elements.

With larger than 24mm x 18mm, issues begin to emerge related to the angle of incidence of light from the objective lens which translates to brightness falloff towards the extremities of the image. It becomes a real problem with wide angle lenses. At this end of the range, the available apertures tend to be narrower than the ideal f1.8.

It is an issue your R&D people would need to be aware of, which is more popularly referred to here as "hotspot" or "vignetting".

I've tried the "traditional" Century 16:9 on front of a 28mm and 50mm. There was bit of an apparent resolution and contrast loss. On some of the older SLR lenses, the whole of the front barrel rotates in focussing, which is why I raised the "back of lens" method.

If this actually begins to go somewhere, P+S Technik might be able to help with data on angles of incidence relating to groundglasses.

Hopefully I have not sent you off on an expensive goosechase.