Need guide for 35mm adapter set up

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yazeus

Member
Dear DVX user member,

I am currently doing a video project that shoots on sony, HDV Z1U. Problems with that is, unlike films it doesn't have the ISO that confuses me with the determining the light reading, furthermore we are not using any field monitor. I can't really trust it's LCD it looks crap from there.

this is my first time shooting on prosumer camcoder, i have been doing some research on 35mm adapter and interested to give it a try.

MY question is: when you are using an adapter, how do you determine the f stop that you will be using? practically the lens and the camera has its own setting right? and once you got the reading right which one that you change? i heard people been saying about the light loss from the adapter, do you compensate your f stop with that as well?

a guy told me that i should put the both of the f stop wide open, if you want to close down or open an f stop do change it through your camera or your lens?

on which lens size do you lock it down to off your internal video camera lens. or its depend on specific 35mm lens that you use? or maybe it is a very relative question?

thank you for helping me with your piece of advice.

regards,

YAZEUS
 
Hi,
Although is true is hard to determine (0r count on) the real ASA (ISO) of a camcorder + another optical system, here is a basic guide (derived from practice):

What do you take into account when shooting film?
ISO, lights (kit and available) and desired lens aperture (assuming 24fps @180 shutter)
A light metter will indicate the light level for the desired aperture.
Lights will be "played" within the films "range" (7 -12 stops) and desired "look" (hard, soft, Hkey, lowkey, etc) to get that effect at the desired working aperture of the choosen lens (for the DOF/perspective desired)
Now, a camcorder has a smaller and linear dinamic range than film. Overexpose (say)two stops and the highlights are "blooming", underexpose and you get "noise". Test the dinamic range of the camcorder using a light meter, determine the desired look and "play" the lights whithin that range (adapter or not).
When using an adapter and you desire the "look" and DOF of(say) 2.8 on a (say 50mm) lens, adjust the camcorder's iris up and down (or the internal/external ND filters) to get a "propper" light level.
If the light is not enough, add some (if the budget and time allows)
All this time, the whole scene should nevertheless be set within the camcorder's range.
Highlights reading (say) 11, shadows reading (say) 2.8, the SLR lens set at (say) 5.6 and the camcorde's iris at (say) 2.8. If the light level is high (is it ever...) add an ND filter or close the camcorder's iris. It will only decrease/increase the amount of light. The ratio (highlights/shadows) is the same. I hope my 2c helps.
Best,
Dan
 
If you are going to try and calculate it: the camera F stop + adapter itself light loss + attached lens F stop = 'technically' an answer hehe. However talked about in a post in the cinematography section, a user proved this not 'accurate'. see here for thread - note "PaPa's" findings.

And pending on adapter used, will determine how far you can stop down before seeing Ground Glass grain. eg: vibrating adapters after about F4 has been voiced by users. Similarly with video camera, the smaller aperture (eg: F8) will increase the depth of field, deepening focus on Ground Glass, leading to grain more evident in images.

All depends what look you want though.
 
Dan pretty much just summarized what Piotr (shot "Free Press clip) was reminded of when lighting his last piece on video+adapter vs film. His experience has been predominanly with film, and certainly shooting on video changes your lighting very significantly. What looks good to your eye may have nothing to do with what will look good in post. With regard to the Free Press piece the HVX200 would have been much happier with higher light levels, brought down later in post for a darker look. Add this information to what Dan has provided:

You should check this clip: http://www.cinevate.com/images/lightloss.mov

It shows that using a light meter with a 35mm adapter may not actually work as predicted as the expected relationship between taking lens aperture and video lens aperture is not 1:1. With the Brevis35 and CF1Le this clip shows that stopping a 50mm lens down to f5.6 only results in about 1 stop loss to the camera. Using CF2Le, or CF3Le ( the other options we offer for interchangable imaging elements)
 
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Thanks for that video Dennis :)
So a conclusion from it: Apart from decreasing depth of field, an F1.4 is not that tempting over an F2.8 or possibly an F3.5/F4 lens, in terms of light loss? (re: when using adapter)
 
Charles, in many cases (but not all) the faster lenses are also sharper at the edges when used wide open. Add to that the fact that many of our users are working with CF2Le, or CF3Le, and these "eat" more light than CF1Le. What it boils down to from my perspective is that folks on a budget, or only using a few slower zooms will find the Brevis and CF1Le very effective. For different looks using CF2Le or CF3Le, then the faster lenses are a requirement.

There's no question that folks like the team at stillmotion.ca (doing a lot of high end wedding work) are huge fans of CF1Le and it's light efficiency. They use up to three Brevis units per wedding shoot.
 
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