How to reduce the depth of field ?

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prokium

Member
Hello,

i own a DVX100a since 1months now, i love this camera,
but the depth of field if very high,
i m searching how to reduce the depth of field as maximum as possible with the DVX100a and accessories (without to use a mini35 that i dont have money to buy !!)
i saw this http://www.centuryoptics.com/products/filters/nd/index.htm
they tell that its reduce the depth of field ... it work with the DVX100a ?? ... well, if people can give me advise "how to reduce depth of field with the DVX100a and some accessories (but not the mini35)

Thanks a lot
 
Re: How to reduce the depth of field ?

...to say that an ND filter reduces DOF is pretty misleading.

an ND filter only cuts down on the amount of light going into the lense.. so that you could..if you chose to.. open up the iris more in your given lighting condition without overexposing everything.. and its the wider iris setting which will reduce the apparent DOF. but the ND filter in and of itself does nothing to reduce DOF.

getting the shallowest DOF is pretty simple. follow these 3 rules..

1. keep the iris as open as possible.

2. be as zoomed in as possible

3. be as CLOSE to the subject as possible so your focusing as close as possible

you will have to experiment with the last two because obviosly you cant zoom in all the way all the time, and be super close because every shot would be a ECU. somtimes its better to let the lense go wider, and get closer so you can pull focus more , and sometimes its better to back off a bit, and zoom in more. it all depends on the framing of your shot, and the situatio at hand ..like how much room you have to work with..


some easy numbers to work with that i find are a nice starting point for a standard CU would be setting the zoom at 60, and the focus at 40.
 
Re: How to reduce the depth of field ?

Ok thanks ,

but there isn't combinations of lenses that can get a better shallow depth of field ?
i dont know .. maybe add a lens that do a better shallow depth of field ... or another accessory that i can use?

these 3 points i know them and i use them but its not all the time possible to zoom a lot and be near the subject ..

then maybe with accessories i can get a better small depth of field without to zoom to much or so.

Thanks

/Yaniv
 
Re: How to reduce the depth of field ?

The only two accessories that can help with DOF are the $10,000 mini35, and the $550 SoftScreen (http://indietoolbox.com). Each has significant limitations, but can deliver the shallow-DOF look you're after.
 
Re: How to reduce the depth of field ?

How about the Century VS16-TC-DVX, expensive as heck, but it pushes your focal length, getting you closer to that shallow DOF.
 
Re: How to reduce the depth of field ?

The lens that Rush mentioned is the 1.6x teleconverter and it does give a narrower depth of field at full zoom. See an example below:

dof.jpg
 
Re: How to reduce the depth of field ?

DOH! How do I forget these things? Of course the tele extender will also help with the look, in the circumstances where you can back up far enough to zoom all the way in with the tele-extender attached!
 
Opps??

Opps??

"getting the shallowest DOF is pretty simple. follow these 3 rules..

1. keep the iris as open as possible.

2. be as zoomed in as possible

3. be as CLOSE to the subject as possible so your focusing as close as possible"

Umm.......


For a shallow depth of field:

Be as far from the subject as possible/practical

Keep the subject at least 8-10 feet in front of the background

Open iris

Use the ND filter to get the iris open further, and/or increase shutter speed

Zoom into the subject

The background and foreground are out of focus, a sudo 35mm look, very effective, somewhat fussy, much cheaper than a mini35.
 
Re: How to reduce the depth of field ?

well,     ..hate to break it to you pookie, but the "Be as FAR from the subject as possible/practical"  thing is incorrect. a shorter focusing distance (not focal distance/zoom..but the distance the lense is focused to) will always yeild a smaller apparent DOF for any given Zoom  setting. this is a basic rule of cinematography.

you can test this by simply finding a subject to focus on.. use any constant Z (zoom) setting you like.. and start off with them in focus  at infinity (MF 93) then get closer to the subject, and shorten your focusing distance.  youll see that the shorter your focusing distance gets(meaning you are closer to the subject..and therefore focusing closer) the shallower the DOF gets. it will be at its shallowest when the subject is flat against the lense.. or whatever the shortest focal distance you can use for the given Z setting you chose is.  IE: if you were at Z99 it would be most shallow when you are focused at MF 50. which is the shortset focal distance aallowed for that zoom setting.. and therefore the closest distance you could be to your subject while keeping them in focus.


..now I know this example uses a constant Z.. but that is really irrelevant. what it concludes is that no matter what Z setting you are at. your apparent DOF would be shallower if your focusing distance was shorter.  

-    the experiment uses a constant Z because obviously if you were at Z99, and focused at MF 93, and then switched to  Z20 and focused at mf 60 your dof would appear to be larger with the second setup which even thoughit uses a shorter focal distance.. cause the lense is so wide that everything is in focus anyway. .. but knowing that a shorter focusing distance gives a shallower DOF.. we know that for either of those zoom settings.. the smallest DOF would be at the shortest focusing distance allowed.

..on almost every example ive posted , ive been asked how i get such a shallow DOF. really its just following the rules i listed

iris open max . zoomed in max. focus pulled max/close to subject max.

..hope this helps  ;)
 
Re: How to reduce the depth of field ?

IAL is completely correct, but I think the reason there's confusion on this issue is because in order to use full telephoto, you usually have to back away from the subject. But, the closer you get to the subject (and the closer you focus), the shallower the DOF becomes. So there are two seemingly mutually exclusive forces at work here.

The two most important factors for shallow DOF are maximum telephoto and wide-open iris. Focusing close is nice too, but if it's a choice between getting closer or using a longer zoom, I vote for the longer zoom. Once you've got your telephoto maxxed out, then you want to get as close to the subject as you can while maintaining proper framing.
 
Re: How to reduce the depth of field ?

..ill side with you on the choosing longer zoom vs  pulling focus more as well.  with the exception of when the subject is smaller than 1 square foot or so (espescially anything smaller than the lense. if the subject is that small. (like in the grass example above)  its possible  to get pretty close -
IE .5 to 3 feet away  from the subject, and pull focus ALOT  since it is so small, and you do not have to be very wide on the lense even though you are close.  so you can maintain enough telephoto, and still get like 6 inches away, and have your focus at about MF 20 or whatever it is for 6 inches..lol anyway  it will yield and EXTREMELY  shallow DOF, and blow out the background way more than the tele method in general the focus will be sharper as well.

..now realistically you dont need a huge blur of the background compared to the zoom way, but i preffer to do it this way because it is easier to focus like that than it is to be still and focus while zoomed in.  but using this method  you can easily shallow the DOF to about 1/8 inch or less for macro type stuff.  of course you can back up a bit and make it bigger as well.

since the amount of dof decrease as a result of focus pulling is on a curve( it does not make nearly as much of a noticeable difference in DOF between MF 93 and 73 which is 20 #s as it does between 50-30.. it shallows DOF more and more on a curve the closer you are focused) , you wont start to see better results from  using a pulled focus VS longer Zoom setting untill you are in the macro range of focus.  

I havent ever really done a clear or precise experiment to determine exaclty at what point the  pulling of the focus will yeild a shallower DOF than zooming in more.. i usually try it both ways if i think its close.. but if anyone is inclined to try some experiments and figure it out, it would be helpful im sure.. generally if somthings that small it going to be the focus pull cause you can get so close, but the bigger the subject.. (like a CU or medium on an actual person..)   the more I rely on zoom.. but just to test it out  anyone can set up a small object like a quarter lying flat oin the table to focus on, and check it out at Z99 with the focus at MF 50, and see how the DOF is vs sticking the lens within 3 feet of the quarter(between 3 feet, and having it on the glass)..  and pulling focus .. youll get a much shallower DOF  being closer, but again.. the bigger the subject, the less you can do that.  and its really unrealistic to do for actual shot of people unless its an ECU.

an example of this would be this shot from my short "soldier"
121072744.jpg

..i was about 2-1.5 feet away..with focus pulled instead of zooming from a further distance.    at times i was probably closer cause the mattbox would hit him in the head.. the gun is only a couple inches in front of his face.
 
Re: How to reduce the depth of field ?

..i wish. Tom Cruise has got to be the most underrated actor ever. He has never won an Oscar.. that is rediculous!! he has been so great in so many films, and gets no respect. can you beleive that? tom Cruise.. no oscar... it just isnt right
:-/ so Tom ..if you ever wan to help an indy guy out.. lets make a movie that gets you that oscar. ;)
 
Re: How to reduce the depth of field ?

IAL, those are excellent, excellent points.  You're right, when you can get *really* close to the subject you can use close focus to really accentuate the shallow DOF effect, as you so ably demonstrated.  The other benefit is that you get a wider field of view in the background, which gives a more open perspective to the shot.

Another brilliant thing you did in that shot was including the gun in his face, to add a third plane of depth.  Because DOF extends for 1/3 the distance in front of the plane of focus, but for 2/3 behind it, it's a lot easier to get something out of focus in the foreground than it is in the background.  Your shot includes both, which gives a nice three-dimensional quality we don't often see in DV productions.

Getting close (which means having to zoom out some) also means you can use slightly wider apertures, which will help a little.  At Z99, your maximum wide-open is f/2.8, but starting at around Z50 you can open up to f/1.7.  Lighting might be a little more challenging with a camera stuck right in the subject's face, but the results could be well worth it.
 
Re: How to reduce the depth of field ?

.. lol you are dead on about the lighting getting a bit tricky with the camera in someones face.. recently i had to do a circular dolly move type shot around a subject with a shallow dof handheld, and the light was behind me! no way around it. the zoom method wouldve been king here, but i had no room. :-/ i think i did the shot like 15 times before i thought i had it without my rediculous shadow on the guy. its a definite drawback of shooting like this.. as is the talent getting claustraphobic.. but most actors are pretty cool with it. as long as you dont hit them in the eye with a matte flag too many times. :P
 
Re: How to reduce the depth of field ?

I wouldn't be surprised if Cruise gets a nomination (and potential win, depending on the competition) for Collateral. He was brilliant in it.
 
Re: How to reduce the depth of field ?

Barry and IAL, I just love your posts, guys. Keep it up.

prokium, your original quesiton was about depth of field. They've covered the basics in this thread, but it is also covered in other threads in Cinematography. Barry has done a nice tutorial on that subject, and I think it is in that section.
 
Re: How to reduce the depth of field ?

A home-made Mini35.

I'd love to see that sucker on a DVX - and then played on an HDTV television. Sounds way to cheap to be good enough quality. If it was though, boy, I'll be the first to use one!
 
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