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a basic doubt about DOF adapters


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#1 Rui Resende

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Posted 05 July 2010 - 04:40 PM

Hello, i have a small doubt about dof adapters. I'll start using one soon, and i have a certainly basic doubt: Basically, if i couple a, say, f/1.4 lens on the adapter, i know i will benefit from the shallow depth of field of that aperture (that's the reason why we use dof). But will i benefit from the ability the lens has to capture available light? or will i have to submit to the main lens of the camcorder, that opens only am f/3 ?

Thnaks for any help on this.
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#2 David Mullen ASC

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Posted 05 July 2010 - 04:49 PM

Generally it's sort of a wash because you are limited by the aperture of the camcorder's taking lens and there is often some light-loss in the adaptor, so it cancels out any benefit in exposure from being able to shoot at f/1.4. You certainly can't gain any sensitivity beyond what the camera's lens allows, only lose exposure from the adaptor.
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#3 Brian Drysdale

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Posted 05 July 2010 - 04:58 PM

This is one of reasons why the DSLR cameras are popular with those people who have been shooting with 35mm adapters. Of course, using these comes with a different set of issues to overcome.
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#4 Brian Rose

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Posted 05 July 2010 - 05:15 PM

Whenever a director brings up the subject of DoF adapters to me, I always strongly advise them to save their money. To be brutally honest, I think they're for suckers. They do nothing for sharpness or clarity, because they are always limited by the camera's primary lens (and indeed, throwing more glass in front probably REDUCES clarity). They make the camera bulkier and necessity rods and additional support. They eat up more light, which is critical considering many cams do not hold up so well in low light conditions.

Their selling point is shallow depth of field, and even that is, in my opinion, rather pointless. When I want shallow DoF, I position the camera further back, or manipulate my lighting and open up the camera. I've never been for want of a DoF adapter, because I have always been able to achieve the desired Dof through application of basic cinematographic and photographic principles.

It seems that many I've encountered who use these gadgets talk about DoF as a "look," like the shaky cam. They even use the term "that depth of field look," which to them means shallow DoF, which they associate with film and hollywood. Shallow DoF = professional. Sadly, they often lack an understanding of just what DoF is, and as a result, are frankly taken for a few hundred dollars by renting or even buying an adapter which, in light of the rise of DSLRs, are increasingly needless.

That's my two cents.

BR
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#5 Phil Rhodes

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Posted 05 July 2010 - 06:54 PM

I'll second Mr Rose. I have used them a few times and seen them used a few more.

There are a few problems.

They can be very expensive to use, because in order to work without utterly destroying your image, they have to be quite carefully made. They require lens sets which are now rare and expensive in light of Red. They take time to set up and, if you're using a camera without removable lens, can require a litany of constant tweaking of the complete optical pathway to get even basic, reasonable results, let alone something really good. It's likely you will lose takes to adapter problems. The problems, if you fail to set them up properly, can be hard to see in a low resolution viewfinder, so horribly easy to miss. They are big and heavy.

I have seen very good stuff shot on them and they do seem to have the characteristic of slighty mellowing highlights, although I'm not sure that's anything a very light promist or ultra-con filter couldn't do. One particular instance was on a reasonably high end commercial which was being shot on an F750 (ergo, onto HDCAM). This was a production which had all the trappings of film, the full crew, a removable-lens camera, etc. This was about four or five years ago and I thought the results looked great and it was a sensible bit of cost saving. On the other hand I've shot with a mini35 on a JVC GY-HD250, also a removable-lens camera, and recorded it uncompressed. The results were sort of on the OK side of slightly underwhelming. Partly this is because it's a vastly inferior camera to the F750; but then, if you're doing spinning ground glass because you're desperately short of cash, well, you're unlikely to be shooting on a super high end camera.

I'm not sure there's much sense in doing it in a world where DSLRs exist, unless for some reason you are hyper-sensitive to DSLR artifacts. I mean, a good DSLR such as the T2i/550D or GH1 is cheaper than a good groundglass rig. If you're considering putting it on something like an EX3 and recording MPEG-2 to SxS cards, then you will get better optical quality, very competitive codec performance and a wider variety of lenses from a GH1.

P
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#6 Brian Drysdale

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Posted 06 July 2010 - 02:19 AM

I have seen very good stuff shot on them and they do seem to have the characteristic of slighty mellowing highlights, although I'm not sure that's anything a very light promist or ultra-con filter couldn't do.


On one 35mm adapter F750 shoot I was on, the strongest impression was the promist effect rather than a shallow DOF. I don't recall the main subject coming any closer than 8 to 10 ft on that job.
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#7 Frank Glencairn

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Posted 06 July 2010 - 04:39 AM

First of all: Adapters are a PITA. Period.

Having said that, a DSLR is no substitute (low resolution, jello, morié, aliasing a lousy codec that brakes apart in grading andwhatnot).

With a good adapter (spinning adapter like the LETUS Ultimate), proper light, good primes and a guy who knows his stuff you can get pretty impressive results, that can not be made by even move the camera far away and zoom in.

The look of a long lens/DOF is much different from a 28, 50 or 80 prime Brian.

Different lighting doesn´t cut it ether.


This here was shot on a HVX200 and a Letus.
With this combination I still blow any DSLR out of the water.



Frank

Edited by Frank Glencairn, 06 July 2010 - 04:42 AM.

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#8 Phil Rhodes

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Posted 06 July 2010 - 05:12 AM

This here was shot on a HVX200 and a Letus.




And a very large amount of money, critically.


P
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#9 Frank Glencairn

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Posted 06 July 2010 - 06:30 AM

I doubt that the same 3 days of production without an adapter would have been much cheaper ;-)

Frank
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#10 Brian Drysdale

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Posted 06 July 2010 - 06:56 AM

First of all: Adapters are a PITA. Period.

Having said that, a DSLR is no substitute (low resolution, jello, morié, aliasing a lousy codec that brakes apart in grading andwhatnot).

With a good adapter (spinning adapter like the LETUS Ultimate), proper light, good primes and a guy who knows his stuff you can get pretty impressive results, that can not be made by even move the camera far away and zoom in.


The resolution on the 1/3" cameras isn't anything to write home about - the best probably being the higher end HDV Canon cameras and the JVC series. The big advantage of the DSLR cameras is the low light sensitivity, but you're also pretty much limited to a shallow DOF because of the moire issues.

On the 35mm adapter job I mentioned, it was shot with a 25mm prime, so it could be a case using the adapter without thinking how appropriate it was in these circumstances and asking did have any real advantage?

Whatever method you do decide to use, the chances are that it will give a different look. You really have pick the one which works for each film.
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#11 Phil Rhodes

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Posted 06 July 2010 - 09:39 AM

I doubt that the same 3 days of production without an adapter would have been much cheaper ;-)




No, but they'd probably have looked about as good, which is my point.
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#12 Chris Durham

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Posted 06 July 2010 - 11:09 AM

Here's the problem with DoF adapters: They're all about DoF. More exactly, they're all about SHALLOW DoF, because you can get deep focus all day long without any help (well, maybe with a little light). So people buy the things - just like is happening now with HDSLRs - under the mistaken belief that shallow depth of field is part of the visual grammar of cinema. It's not. SELECTIVE FOCUS is - the ability to bend focus to suit your needs.

With an adapter, though, forces conspire to keep your focus shallow, rather than selective. One is the aforementioned mistaken belief that shallow is better - shallow focus is a lazy way of making a pretty picture. Another is the "I spent money on it so I need to use it" mentality. The other big problem is that once you've got it on the camera and set up, you don't want to take it off, and since you're losing light because of the thing, you're more likely to shoot wide open.

HDSLRs aren't so bad. They have they're own problems, and an undisciplined shooter is still an undisciplined shooter; but you can at least get over the physical limitations of an adapter.
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#13 Frank Glencairn

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Posted 06 July 2010 - 06:17 PM

With an adapter, though, forces conspire to keep your focus shallow, rather than selective. One is the aforementioned mistaken belief that shallow is better - shallow focus is a lazy way of making a pretty picture. Another is the "I spent money on it so I need to use it" mentality. The other big problem is that once you've got it on the camera and set up, you don't want to take it off, and since you're losing light because of the thing, you're more likely to shoot wide open.


If you have a spinning adapter, there is no reason not to stop down and control DOF as much a you wish.
Good adapters only loose half a stop of light, so it´s actually a no brainer.

Frank
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#14 Ramiro Teran

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Posted 26 July 2010 - 02:52 PM

Great short Frank

Hi guys,
I just got an used Letus extreme. I have an Ex1. When I try to align it zooming out I can only align it with the paralel lines of the viewfinder, but the GG is not in the center of the viewfinder, is off to the right, so when I zoom in to avoid vignette it seems that I have to zoom in more to compensate. Any help ?
Thanks !!
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#15 James Byrne

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Posted 29 July 2010 - 04:52 PM

Hope this question is ok to post here. I believe I'm in the right place.

Judging by the conversation here, I'm going to be blasted as I am someone who has built my own depth of field adaptor for a Sony Z1.

I am a technical n00b. Really I am, so bear with me. I built the adaptor with a friend of mine who is much more technically able than me. We used a tutorial on the internet.

My problem is now, that the image is inverted. I have read up on this and I do know that because it is an optical lens, when the light goes into the lens it is bent so inverts the image. In a camera there is something to flip the image back over so it is the right way up in the LCD screen and viewfinder.

What I am asking for, is if anyone has any tips on how to not invert the image? Or even to invert it again?
I really dont know how to solve this problem. I do have a few ideas.
Can I turn off the thing that flips the image in the camera?
Can I put another lens into the adaptor to flip the image again? (to put it right)
I also though, a really cheap and easy way to solve this problem would be fix a small mirror to the top of the view finder so at least I could see the image the right way up.

What do people think?

Just so you know, I do know this is a silly question. I do know I shouldn't have myself in this situation in the first place. And I do know that some of the people here are far above this problem. haha. But I am a student, Im learning. PLEASE HELP!!!!!!!!!
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