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Old December 29th, 2003, 10:57 PM   #1
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Two Questions

Question One: What is the oscillation for?

Question Two: 35mm film lenses have really big $$$ attached. 35mm camera lens much less so. What cost lenses do you need with this device?

Thanks,

David
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Old December 30th, 2003, 02:02 AM   #2
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David:

1) Without movement, the grain of the ground glass is visible, like looking through a screen door.

2) How do you define "need"? If one is used to working in a cine environment, still camera lenses will present a major challenge to work with in terms of pulling focus. Cine lenses have carefully calibrated distance markings, allowing for marks to be laid and/or accurate focus to be pulled by an assistant. They are also designed to be used for motion picture work and thus generally do not breathe as they are racked through their range.

Still camera lenses are much more affordable, so if the goal is to own a set of lenses, that would make more financial sense. However, for years most indie filmmakers did not have an expectation to own camera packages, instead renting partial or complete setups for projects. The cost of renting a set of good cine primes may be cheaper than buying a set of still camera lenses.

It all comes down to what you have planned for your projects.

I believe that as exciting as shallow depth of field is for a growing number of DV filmmakers, the realization is slowly emerging that maintaining focus at T2 is a big challenge. Having the background out of focus is cool and all, but if it's at the expense of having the foreground go in and out of focus...?
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Old December 30th, 2003, 10:17 AM   #3
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Charles speaks the truth! His post is absolutely spot-on and should be read by all potential mini35 users.

Foreground focus is difficult to obtain, but can be very sharp if you're extremely careful.

As for still vs. cine lenses, as Charles said, cine lenses are designed for cine work and are much easier to work with (i.e., there's no such thing as "rack focus" with a still camera, so the lenses aren't designed to accomodate that!)

With that said, I had the opportunity to use some Zeiss SuperSpeeds and some Zeiss still-camera lenses on the mini35. The SuperSpeeds were faster, of course (about T1.3, vs. about T2.0 for the still-camera lenses). That makes a difference, for sure. But with adequate lighting, the two lens systems were nearly indistinguishable on video. I shot with the SuperSpeed 85mm, and then the same subject with my Pancolar 80mm, and there was no discernable difference. It was my conclusion that standard-def video doesn't have the resolution to take advantage of the additional sharpness afforded by the newer glass. Which was good news for me, since I have a whole stockpile of these lenses, and it's good news for potential mini35 users since these lenses can commonly be found on ebay for around $60-$100 each. You could collect a set of 20mm, 35mm, 50mm, and 80mm for probably under $500.

Cine lenses are much nicer to use, and the newer lenses are much faster -- but for the budget-conscious, these Zeiss Jena M42 lenses (with M42->Contax adapter, and Contax lens mount on the mini35) are plenty good enough!
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Old December 30th, 2003, 11:12 PM   #4
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More questions:

Couldn't the glass be ground fine enough not to need an oscillation to prevent graininess?

Could a 16mm lens be used to get a larger DOF? Wouldn’t this just require zooming the camera for the smaller image size? (In addition to lens mounts).

Can zoom lenses be used or are they too slow?

Does this mitigate disadvantages of 1/3” CCD vs a ˝” or 2/3” CCD?

Do standard rod mounted follow focuses work? That is, do the rods work? And if so, how?


Thanks,

David
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Old December 31st, 2003, 02:26 AM   #5
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Re: More questions:

<<<-- Originally posted by David Ziegelheim : Couldn't the glass be ground fine enough not to need an oscillation to prevent graininess?>>>

Apparently not.

<<Could a 16mm lens be used to get a larger DOF? Wouldn’t this just require zooming the camera for the smaller image size? (In addition to lens mounts)>>

A setup like this optimized for 16mm would indeed give a larger DOF...but is that desirable? Perhaps you meant smaller DOF, in the way that 35mm has a smaller (really, shorter) DOF than 1/3" video. If this is what you meant, then 16mm is going the wrong direction. You would end up with something like the DOF of 2/3" video on a 1/3" camera, not a huge accomplishment, certainly from a cost perspective.

<<Can zoom lenses be used or are they too slow?>>

They certainly can. I've used a 25-250mm Angeniuex, it works perfectly. The only issue is with lenses that are 5.6 or greater with the earlier versions of the Mini35; the ground glass may become visible as a result.

<<Does this mitigate disadvantages of 1/3” CCD vs a ˝” or 2/3” CCD?>>

In terms of DOF, yes.

<<Do standard rod mounted follow focuses work? That is, do the rods work? And if so, how?>>

The rods on the Mini35 follow the specs for standard mini-rods and are fully compatible with follow focus and matteboxes as used for 2/3" video and Arri 16/35 setups.
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Old December 31st, 2003, 01:10 PM   #6
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Some points not picked up on here are

the vast difference in image size between movie 35 (27.2 mm dia) and still 35 (43.2 mm dia), I am not sure if the mini35 takes full advantage of this but I am sure a copycat device will. Image reduction to SD will almost half any grain present in the ground glass and slim DOF will be that easier to achieve. A non moving ground glass might be an option if a Hasselblad acute matte screen where to be used (very bright and quiet)

also the mag change due to breathing is always a fix it in post option but there will be those who will master a fixed mag during focus without it

however the use of SLR zooms would be weird as they are mostly twist and pull for focus and zoom

the majority of famous brand SLR lenses are more than good enough for HD since they exceed 50 LPM

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Old December 31st, 2003, 01:28 PM   #7
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A couple of follow ups.

Follow up 1:

It is my understanding that sometime the DOF in 35mm is too short. I read somewhere, that in the pre-video days being able to get a greater DOF was a goal.

I thought that the Mini35 may have given the option of controlling DOF by changing image size.

Follow up 2:

On rods, if I read the answer correctly, the Mini35 has its own rods for the focus and matte box. Is that correct? And if so, what holds the weight of the Mini35?

Follow up 3:

What is a Hasselblad acute matte screen?

Follow up 4:

What is a "mag change due to breathing"?

Follow up 5:

Is a matte box usable with still camera lens?

Thanks,

David
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Old December 31st, 2003, 05:52 PM   #8
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1) Yes, it is desirable to adjust the DoF, which can easily be done by adjusting the iris on the film lens. The newest Mini35 allows this throughout most of the film lens (aka taking lens) travel; the older ones restricted stopping down past 5.6. At a certain point, one would be achieving a similar DoF to that of a standard lens on a DV camera (albeit retaining the optical characteristics of the film lens), so it may not be worth it at that point if this deep focus look was the goal.

2) Yes, the Mini35 has its own rods as I described above. It also supports the camera itself. You mount the Mini35 to the tripod, not the camera.

I'll let John J. handle the others as I'm not quite sure what he was referring to re: mastering a fixed mag. John, perhaps it would be a little clear if you didn't abbreviate here--mag=magnification, yes?

Also, not sure I get the point about the ground glass size--regardless of the format of the lens system (cine vs still), the video camera is re-photographing a groundglass at a fixed distance...?
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Old January 1st, 2004, 05:36 AM   #9
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Charles & David

on 3 / a Hasselblad acute matte screen is a $300, 60x60 mm, very fine focusing screen used in Hassleblad cameras (the camera they took to the moon in '69)

here is a pic

http://i3.ebayimg.com/01/i/01/08/e5/16_1.JPG

(aside -maybe 'video tapping' a Hasselblad is the way :)

on 4 / the mag change due to breathing - SLR lenses (and some old Fujinon video lenses) change image magnification when the focus ring is turned (a sort of mini zoom) - an operator intimate with a SLR zoom lens can compensate (master) for this, else it can be fixed in post

on 5 / yes matte boxes are ok or you can use a lens hood like those made by LEE filters

http://www.leefilters.com/images/Cp/LensHoods/f19.jpg
http://www.leefilters.com/images/Cp/...7x2filters.jpg

WRT to cine/still image size on ground glass - the point is that the bigger still lens image is reduced to SD and the granularity in the ground glass is also reduced in proportion - thus having an almost x2 advantage over the cine lens-

I am not sure that the MINI35 can accomodate the full 43+mm image circle you get with a still lens since it looks geared for 16x22 mm format cine lenses?
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Old January 1st, 2004, 01:36 PM   #10
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OK, I see your point John. I know that the Mini35 can ordered with a still lens mount and I'm sure that it retains the full image size of that format, so yes, it is possible that the granularity is somewhat reduced with that system. Perhaps after the holiday Mizell will be able to chime in on this.

Regarding the breathing issue--I have attempted to "zoom out" breathing over the years when forced to do a big rack on a zoom with mixed results (it can look jerky, thus worse than the breathing itself). The 12-120 Angeniux 16mm zoom was one of the worst for this characteristic. I can't imagine trying to deal with this on a still camera zoom that uses the "twist and pull" system you mentioned earlier, ugh.
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