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filters on digibeta


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#1 Sander van de kerkhof

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Posted 26 July 2006 - 12:42 PM

hi,

I need to use some filters on a Digibeta soon i.
since i never used them before i have a couple of questions about this matter.

1. if for instance i would use a 1/8 black promist and a polarizer do i need to take them out when i white balance or can i keep them in front of the lens?

2. is there a particular order in wich filters are placed, would you put the polarizer in front or behind the promist or the other way around?

3. do i need to change the density of a promist when i make a close or a wide shot... for example use a 1/8 on close ups and a 1/4 on long shots?


thnx in advance.

Sander
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#2 Sergi Vilanova

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Posted 26 July 2006 - 01:28 PM

hi,

I need to use some filters on a Digibeta soon i.
since i never used them before i have a couple of questions about this matter.

1. if for instance i would use a 1/8 black promist and a polarizer do i need to take them out when i white balance or can i keep them in front of the lens?

2. is there a particular order in wich filters are placed, would you put the polarizer in front or behind the promist or the other way around?

3. do i need to change the density of a promist when i make a close or a wide shot... for example use a 1/8 on close ups and a 1/4 on long shots?
thnx in advance.

Sander



Hi Sander:

1: In theory, white balance is only a color correction device, so both pro-mist and pola shouldn't affect at it. Nevertheless, since both of them (specially the pola) do affect the way light hits your lens, and also as a general rule or working method, I would do it with my lens clean.

2: There is no particular order in which flters are placed, although the general rule is that you place first (that is, closer to the lens) the one you will use the most through out your shooting.

3: Again, it's a matter of theories and taste. Here in this forum is been discussed before, and I think it was Mr. Mullen who posted the two main theories about it. One, that yes, it depends on the percentage that the foreground occupies your frame (that is, a close up of someone's face even done with a wide lens). Two, that it depends on the lenses you use: The tighter the lens the most you notice the filter's effect. In my experience, that last one is the one that comes closer to the truth.

Good thing is that, since yo are filming in video, you DO get what you see on the monitor, so just check and try what you like the most.

Hope it was of some help
s.
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#3 David Mullen ASC

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Posted 26 July 2006 - 02:03 PM

My point before was that the two theories regarding filter strengths are somewhat contradictory, but depend on what you are trying to do: match resolution or match the perception of detail.

Technically, longer lenses should get less diffusion than wider lenses, but conversely, longer lenses tend to be used for tighter coverage where you generally need or want less sharpness than in wide shots, which tend to use wider lenses.

So the deciding factor is really image size + focal length. If you are doing wide-shots with a telephoto lens, you'll need to use less diffusion to match wide-shots on wide-angle lenses. But if you are doing close-ups with the long lens and wide shots with the wider-angle lens, you probably want more diffusion on the close-ups because your eye expects to see more detail in the wide shots, but doesn't need to see every pore in a close-up. This is one reason why in low-rez formats, the close-ups generally look acceptably sharp but the wide shots fall apart: our eyes/brain wants to see more detail in a wide shot.
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#4 Laurent Andrieux

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Posted 26 July 2006 - 05:12 PM

As for the two first questions, I second the statment that it's better to do your balancing with these filters on. You see, you don't expect these filters to affect the chroma. But they may do so , balancing will neutralize any color shift, that you would have correct in post if shot film.

Of course, in the case where you put a filter with an aim of color effect (coral deg for instance or sunset...) then you should not balance with this kind of filter, and eventually grade in post.

If ever you did not balance with the pola or any diffusion promist - whatever that should not affect the chroma - on, don't worry, you should easily correct in post, if ever needed... If you can grade in post.

About how to locate the filters, I understand what is said, but it's not a point with the effect of the place of the filter, but rather just an easy wait to set things (As not to forget something, know where it is etc. more like an assisting point of view). I consider one should always place promist and any diffusion filter as close from the lens as possible, because - as it's been mentionned - the filter can be felt with a lens when it enters its depth of field, be especially carefull with wide lenses and small apertures.

About the pola, you can have a ring one or a square one. In the case of a ring you usually have no choice. In the cas of a square, you usually have only one or two position that allow turning the filter on the matte box, so that you have to put the pola in one of them (or this one) only.

Some filters are more pricy than others or more often used, I don't like them in front (may be a point about putting the ones you use much closer to the lens).

Just my 2 cents
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#5 Michael Nash

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Posted 26 July 2006 - 05:40 PM

I always try to put the diffusion filter closest to the lens, to protect it from as much stray light as possible. This keeps the contrast more consistent from shot to shot. ND's always go in the front, if possible.

Some matte boxes have a round or rotating filter stage closest to the lens, so you don't always have much choice where you can put the pola.
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#6 Tom Bays

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Posted 26 July 2006 - 06:27 PM

sorry to change the subject a bit, but i have a mountable zoom thru on my digi beta. Is there a decent series of fixed lenses that are directly mountable.
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#7 Michael Nash

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Posted 26 July 2006 - 06:34 PM

sorry to change the subject a bit, but i have a mountable zoom thru on my digi beta. Is there a decent series of fixed lenses that are directly mountable.


Any of the HD primes made by Zeiss, Canon, and Fuji should fit on your digibeta camera.
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#8 Tom Bays

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Posted 26 July 2006 - 06:46 PM

without cumbersome adapters? would they be too heavy? I have to get more mobile.
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#9 Michael Nash

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Posted 26 July 2006 - 07:17 PM

without cumbersome adapters? would they be too heavy? I have to get more mobile.


I'm not sure what you're asking -- you want to be more mobile, but you want to keep swapping prime lenses? Is there something about the current zoom you don't like?

HD primes are designed to fit directly on any 2/3" video camera with a B4 mount (no adapters needed). The lenses themselves are not that heavy or cumbersome, but since they're designed for "cine" use you really need a follow-focus to use them, since the focus rotation is larger than on an ENG lens.
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#10 Tom Bays

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Posted 26 July 2006 - 07:35 PM

My zoom thru goes on directly and I tighten a screw to keep it on. That is what i meant by fast.
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#11 David Mullen ASC

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Posted 26 July 2006 - 07:53 PM

My zoom thru goes on directly and I tighten a screw to keep it on. That is what i meant by fast.


B4 primes go on the same way as B4 zooms, so I don't understand what you're asking. I think you're thinking of cine primes that need some sort of intermediary adaptor.
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#12 Tom Bays

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Posted 26 July 2006 - 11:41 PM

when i shoot with the DVW-790 I usually do generic local spots and If i need the zoom...i just take of the lens shade and screw on the zoom in its place. I was curious what fixed focal length lenses might be available to use in the same fashion. I shoot some pretty long buildings sometimes and the wide angle zooms just don't get the job done. I also shoot in some pretty bad environments at times that don't allow me the luxury of backing up 15 feet to get backgrounds out of focus.
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#13 David Mullen ASC

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Posted 26 July 2006 - 11:47 PM

when i shoot with the DVW-790 I usually do generic local spots and If i need the zoom...i just take of the lens shade and screw on the zoom in its place. I was curious what fixed focal length lenses might be available to use in the same fashion. I shoot some pretty long buildings sometimes and the wide angle zooms just don't get the job done. I also shoot in some pretty bad environments at times that don't allow me the luxury of backing up 15 feet to get backgrounds out of focus.



I don't understand -- you screw a zoom lens onto another zoom lens where the lens shade goes on???

Zoom lens on a DVW-790 would normally just go into the B4 video lens mount, same as the prime lenses. It's a bayonet mount.

Are you asking about long prime lenses or longer zoom lenses or zooms with teleconverters? Or faster prime lenses that allow you to open to a wider f-stop than the zoom?

Fujinon, Canon, and Zeiss all make HD prime lenses.
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#14 Tom Bays

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Posted 26 July 2006 - 11:56 PM

I'm sorry to confuse you david :D If you click on the link MPS below you will see our camera drop down in the animation(in the box). The zoom would be an attachment to the lens that we purchased with the camera.

Edited by Kemper, 26 July 2006 - 11:57 PM.

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#15 David Mullen ASC

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Posted 27 July 2006 - 12:00 AM

I'm sorry to confuse you david :D If you click on the link MPS below you will see our camera drop down in the animation(in the box). The zoom would be an attachment to the lens that we purchased with the camera.


The lens on the camera is a zoom, isn't it? Doesn't it come off?

I still don't understand -- unless it is a permanently-mounted zoom like on a consumer camera, you don't attach a lens to a lens, you replace the lens with another lens. You take off that zoom on your camera and put on whatever rented lens you need to use, whether it is a more telephoto zoom or a prime lens. Are you thinking of teleconverter attachments or something?

You're not actually thinking of attaching a zoom lens to your zoom lens???

Look near the bottom of this page at the wide and tele converter attachments -- is that what you're thinking of?
http://www.fujinonbr...i?idAccessory=8
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#16 Tom Bays

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Posted 27 July 2006 - 12:09 AM

It's an 8X Zoom-Thru Wide Angle Converter.

The .8X Wide Converter attaches quickly to the front of a zoom lens, effectively shortening its focal length while maintaining full zoom capabilities.

Attach the .8X to the front of a lens for 20% more coverage when set to wide angle, telephoto or anywhere in between.

Like Century's other wide angle attachments, the .8X reduces minimum object distance (MOD) allowing the camera to move considerably closer to the subject while maintaining focus.

Posted Image

Edited by Kemper, 27 July 2006 - 12:11 AM.

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#17 Laurent Andrieux

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Posted 27 July 2006 - 01:10 PM

Ok, this is a wide angle converter for a zoom lens... No problem, so, by now, what is your need, do you mean you are nor satisfied with that converter + zoom and want to get another zoom instead, or a prime lens for wide shots ?
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#18 Tom Bays

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Posted 27 July 2006 - 01:42 PM

with the wide angle converter i'm going to get some issues the wider and tighter i get. I was curious if there was a fixed focal length converter to use the same way whether it be wide or telephoto instead of using the zoom. Am I making sense.

I guess the example would be...I you click on the link below and look at the spot that is for gilkey windows (under animation) We used some digi primes. The final shot is of a rather long building....there is no way i could get that shot with the wide angle converter. I wondered as stated above if there was a converter that was as simple to mount, but still get the same look if not quality as the digi primes.

Edited by Kemper, 27 July 2006 - 01:47 PM.

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#19 Tim J Durham

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Posted 27 July 2006 - 02:27 PM

with the wide angle converter i'm going to get some issues the wider and tighter i get. I was curious if there was a fixed focal length converter to use the same way whether it be wide or telephoto instead of using the zoom. Am I making sense.

If it's a wide angle CONVERTER, it has to be attached to a lens. You can't just shoot with the converter alone.

I guess the example would be...I you click on the link below and look at the spot that is for gilkey windows (under animation) We used some digi primes. The final shot is of a rather long building....there is no way i could get that shot with the wide angle converter. I wondered as stated above if there was a converter that was as simple to mount, but still get the same look if not quality as the digi primes.


No, there is no converter for the front of a zoom lens that will give you the same look as a Digiprime lens. You may arrive at the same field of view, but the quality will be vastly inferior. Fuji makes a fisheye adapter for its zoom lenses but I doubt that's what you want. It sure is wide, though.

Perhaps you could just rent a wider zoom than the one you have?

Are you the one shooting this?
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#20 Laurent Andrieux

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Posted 27 July 2006 - 03:32 PM

I suggest you go and see what prime lens look like on your camera, the prices etc. at your local dealer or rental house.
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