50MM lens at F/11 - F/16

Stephen Bruno

Stephen Bruno

Member
Hi Folks, I am about to shoot a short film with a homemade 35SLR adapter and the DVX100A, of course, Im using the adapter to get shallow DOF and to be able to use some rack focusing. However, I do not intend to have shallow DOF for the entire film, i will have some wides and mediums that will call for a much deeper focus...

The question is weather or not stopping down is going to cut too much light out of the already 2-3 stop loss adapter and lens?

Have any of you found a way to illiminate this problem? I know its hard to answer without knowing the light loss of the adapter im using and untill I do some test, its hard for even me to say. I guess im looking for what to expect before I go into the tests, that way i'd be a step ahead to solve the problems i might run into.

if it helps, I know that i will be using a Nikon 50mm F/1.8 Series E.

Any and all advise is appreciated.
 
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Are you asking how to get deeper focus (larger depth of field) for your medium and wide shots? If so, these are your options:

1) Why not shoot using the stock dvx lens? You can achieve many different levels of dof (depth of field) with the stock lens by utilizing your lens length (amount of zoom)

2) You can switch to a shorter focal length lens. Going wide and moving in will also increase your depth of field.

3) You can stop down (like you mentioned), but you will need more light. This method works if you can afford to stop down or add light.

4) Your depth of field will also increase as the distance between the camera and subject increases. This is the method I really have yet to see as useful. You really cannot manipulate this one as much as the others. If you move the camera back away from the subject the dof increases slightly, yet you lose your composition. If you then use a longer focal length lens to get your composition back, you just made the dof grow shallow again! Dont ask me! :)

Use any combination of these methods to achieve the best result for the situation you find yourself in. If I misread your question let me know!

-best of luck
 
no, you didnt mis read, I thought about just using the stock lens, but then I figure to be doing some serious timing and matching in post. From what ive seen these adapters create a very cinematic look, and although the DVX lens is great I feel that stopping down and keeping the nikon lens on, will keep the cine look i need. Althoug I will be color correcting, I'm Trying to solve as much as I can at the lens.

What im discovering, I will need more light for the wide shots...

So, I guess this is what I'll expect either way, I was just afraid that i would need even MORE light because of the adapters loss.

Kinda stupid of me to ask before I test, but at least now I know to budget more light for my wides and mediums.

Also, you mention using a shorter focal length, so if I were to throw on a 28mm that would make my wide shots sharper?

thanks.
 
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Hummm. I dont know much about your adapter... but most the adapters i've worked with, it is not good to stop your cine/still lens down past T2.8 or T4. If you do you start to see the grain from the ground glass. With the g35 its a static GG and worked best for me around 2.8... but the Pro35... I shot mostly at T2 on my Cooke S4, if I went to T2.8 I could see the ground glass moving and even at T2 (Wide open) Some of the footage you can still see it if your shooting in bright areas like ext. w/ snow scenes. You really need a low con filter to hide it sometimes. I would probably suggest not useing your adapter for deep focus shots you have planed. You can mix the two to and extent for sure.
 
Stephen, Yes, a shorter lens does have a larger depth of field. It would certainly help to use a wide angle. Maybe then you wouldn't have to stop down as much. The best way to figure this out, is to test, or what I often do.... is just look it up on a dof calculator.
http://www.dofmaster.com/dofjs.html
It is very useful to see what stopping down, moving subject back, or using a shorter focal length will do. It may not be accurate for adapters, for I have not tested it, but it will give you a pretty good idea.

I like playing with the dof calculator.... I am a dork.
 
yeah, I have a 28-80mm zoom on my Nikon N55 and I shot some tests and realized what you were saying, thanks for the tips dude. With a 28 or 35mm on the adapter all should be well...


Thanks again, take care

Stephen
 
=Prodigy= said:
Are you asking how to get deeper focus (larger depth of field) for your medium and wide shots? If so, these are your options:

2) You can switch to a shorter focal length lens. Going wide and moving in will also increase your depth of field.

4) Your depth of field will also increase as the distance between the camera and subject increases. This is the method I really have yet to see as useful. You really cannot manipulate this one as much as the others. If you move the camera back away from the subject the dof increases slightly, yet you lose your composition. If you then use a longer focal length lens to get your composition back, you just made the dof grow shallow again! Dont ask me! :)
Click to expand...

Well, point 2 and point 4 seems to contradict each other. Actually point 2 is wrong. Going wide and moving in does not give u more dof, even the same composition and f-stop. Your only option is to use more light and stop down the iris of the lens. otherwise, as said before, use the stock lens.
 
hiderocketdive said:
Going wide and moving in does not give u more dof, even the same composition and f-stop.
Click to expand...

Actually, he's right. Using a wider lens will give you a deeper depth of field; see the images on page 24 of Cinematography by Kris Malkeiwicz: "Long, medium, and wide angle lenses used at different positions to obtain similar framings....notice the depth of field diminishing with longer lenses."

However, if you want to get that "human eye" perspective or whatever, 50mm is the only focal length. Personally, 35mm still feels wide to me although this is only really pronounced in close ups. I do not like the idea of using wide lenses to increase dof in close ups since wide lenses feel very different from telephoto lenses and convey an entirely different message, but it is a possiblity if you're shooting deep focus and want the background to be prominent in the frame.

As for the amount of light you'll need, I usually find that to light a very small room with white walls on a 35mm adapter, I'll need maybe 500w of lights; 2000+w for a larger room. That's at f1.4 or f2 and with high key lighting, so depending on your style you can get away with less (or may be forced to use even more.) At f11 or f16 you'll need six stops more light, so that would be around 32,000 watts of light for a small room. Realistically, you probably won't need this much and definitely will get a visible exposure with a tenth as much but the underexposure will look grainy and ugly. Also, it's just hard to control that much light.

As for the "cinematic" contrast, I refer you again to Malkiewicz: "With greater depth of field, more elements in the picture are in sharp focus...There is also an impression of higher contrast...becasuse when a background is out of focus, the bright highlights and dark shadows tend to blend into a muddle of midrange values, so when they come into sharp focus, the high and low brightness values are more prominent." So the contrast is largely an illusion, but most 35mm adapters (including my G35) have the effect of a controlled flare, which changes contrast pretty significantly by washing out the darker ares. All this really does is effectively raise your master ped setting, but if you want to do it optically just buy a Tiffen Ultra Contrast with a high number (never used one, but I assume +3 or +4 would be good.) Also, my G35 is unusable except at f1.4 and f2 (I'm removing grain from something shot at f4 now and it's very near to impossible) and even the mini35 has issues beyond f2. So my advice is to shoot with the dvx's stock lens and maybe some filtration (fog and ultra constrast maybe?). In terms of depth of field, f2 should be a lot like f11, f2.8 a lot like f16.

Also consider split diopters if they are called for in your shots and you want to maintain a single f-stop (as is common practice) during a scene and are using an adapter.
 
Great Info Policar, I appreciate you taking the time to explain that. I figured the adapters would start to loose there touch at about a couple stops under.

Of course, I will still test, My main concern was having a heads up before the tests took place. I have figured to use a 28mm for all the masters and wides, I notice that there still is slightly shallow DOF and selective focus which I like, but yet deep enough to not completely wash out my back drops. It would kind of make no sense to even have a production designer if I keep washing out her work ;)

Plus, I will not have a follow focus or focus puller so the few racks I will have will take place at the barrel, and the stedicam track, forget about it. The 28mm will solve this problem and still give me a more cinematic focus and contrast then the DVX stock lens. Thanks to you and Prodigy for shedding some light ;)

Take Care
 
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