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35mm lens adapter and aperture control

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clyde villegas
35mm lens adapter and aperture control
on Aug 5, 2010 at 7:42:45 am

When attaching my 50mm f1.4 lens to my depth-of-field adapter, the SLR lens' aperture cannot be manipulated anymore. For this reason, if lighting condition is too bright, I simply increase my camera's f-stop so less light will come in. My idea is that since the depth of field is being controlled by 50mm lens and that the camera is shooting a flat object (the ground glass), I can manipulate the camera's aperture without affecting depth of field. Do you guys also do this to control the light coming in, or do you just slap in filters in front of your SLR lenses? I chose the first one so I don't have to buy filters.

ut in omnibus glorificetur Deus


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Todd Terry
Re: 35mm lens adapter and aperture control
on Aug 5, 2010 at 2:31:09 pm

It depends on which DoF adapter you are using.

You SHOULD be able to use both the lens' aperture ring as well as the camera's exposure controls to find a balance that gives you the DoF you want as well as proper exposure. Unfortunately, you are using lenses that does not allow you iris control on the adapter (I'm guessing you are using SLR lenses designed for a different purpose).

No, manipulating the camera's iris control no longer has any effect at all on DoF, that is now a function solely of the front lens. Since yours is always shooting wide open, you will always have the shallowest DoF that lens will allow.

I personally use a combination of things. I use the P+S Technik converter, which does not use the camera's native zoom lens... you take that lens off and attach the converter directly to the camera body with just a little relay lens. That little relay has another iris in it, which I primarily use for exposure. The cine lens' iris then I primarily use to control DoF (and frankly, I usually keep it pretty wide). In some instances, I will put neutral density filters in the matte box. A combination of these three things gives me proper exposure and the desired DoF.

You said you don't want to buy any filters, but frankly you need to... they are an important tool (actually what you really need to get are different/proper lenses, but the filters are a cheaper temporary fix). What would be most helpful is a set of three ND filters (.3, .6, and .9). If you use gelatin or polyester filters they are actually very cheap. You can pick up a set of three 4x4 ND filters for less than a hundred bucks.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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clyde villegas
Re: 35mm lens adapter and aperture control
on Aug 7, 2010 at 9:59:49 am

Can I use this filter:

http://cgi.ebay.ph/Green-L-77mm-77-mm-Neutral-Density-ND-8-ND8-Filter-/2802...

But the numbering on these filters are different, it's just ND8. Yours are decimal numbers (.3, .6, .9).

ut in omnibus glorificetur Deus


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Todd Terry
Re: 35mm lens adapter and aperture control
on Aug 7, 2010 at 5:09:40 pm

I've seen consumer ND filters number like that in the past, but honestly I don't know what the numbers mean. You could probably Google and find some kind of scale.

ND filters for cine use will have the decimal numbers, and ideally you should have a set of at least three, not just a single "catch all" filter... especially if you are going to be relying on them so heavily for exposure control since your front iris is inoperabe. A .3 ND filter reduces light by one stop. A .6 reduces light by two stops, and a .9 by three stops.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com






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clyde villegas
Re: 35mm lens adapter and aperture control
on Aug 7, 2010 at 10:22:29 pm

Thanks, Todd! That's very informative.

ut in omnibus glorificetur Deus


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clyde villegas
Re: 35mm lens adapter and aperture control
on Aug 8, 2010 at 11:50:37 pm

[Todd Terry] "actually what you really need to get are different/proper lenses"

Talking about lenses, what are the essential lenses that I need to have, aside from the one the I have now which is a Canon 50mm f1.4 SLR lens?

I also found these filter holder and filters on Ebay.

http://cgi.ebay.ph/ws/eBayISAPI.dll?ViewItem&item=140336236894&ssPageName=S...

http://cgi.ebay.ph/ws/eBayISAPI.dll?ViewItem&item=110568801996&ssPageName=S...

What can you say about them?

ut in omnibus glorificetur Deus


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