Joined: 07 Sep 2006 Posts: 699 Location: Washington DC
Posted: Wed Mar 23, 2011 9:45 pm Post subject: Shallow depth of field when shooting SLR videos (cheap)
Sorry guys, I did not notice that you were still posting down here. I thought this section about photography was dead, then I scrolled down the other day just to discover that there was still some life down there. I should have a wider screen...
So here we go:
Shallow depth of field with the SLR (video).
Any SLR (with video mode : - ) would grant you marvelous 720p video with very shallow depth of field. This is not like the canon would do it and the nikon would not or vise versa. This is not a matter of lense quality either: a 50mm f1.8 (probably 50US$ on ebay) would do / actually this is the one I prefer for this type of shooting. All those machines and glasses have more in the box than you can use anyway, and even more true with videos. The thing is that you would need a couple of extra bucks to make it pleasant i.e., to manage shallow depth of field in videos. Here is how.
First check the demo below (that is, for those who have no clue about what I am talking about). The aim is to get a shallow depth of field (not always, but say for portraits, stuff like that). The video is a piece of crap, but it does not matter. Just type " ND filter video" somewhere on the web and you will get tons of other samples.
BUT, when you are outdoor shooting video (let me know if I go to geeky here), you get more light that you need and therefore you have to "close" your aperture, and then you loose the narrow depth of field that everybody like for close shoots, portraits, some actions even. Are you still with me? Say Iso100, speed 1/60s, well you are still at stop F10 or F16 etc when it is sunny (when the videos are the most pleasant) and you cannot have this crisp foreground with blurry background, or the other way around.
Of course we live in a world of wonders so you have a piece of equipment to help you: The NEUTRAL DENSITY filter. This magic simply "darkens" the front of your lense, like if there was less light. Your camera gets that and you can "open" your lense to F4, or F2.4, or F1.8 whatever you have on your lense when it is wide open. Wide open means shallow depth of field (and the more telelense, the narrower the depth of field), see the 101 on photography and depth of field.
At this point I am positive all the non-video, non-photography guys are back on facebook and I can continue with the real men:
Here is the deal: ND filters cost a fortune probably several hundreds on average. You would need one for each different diameters if you have several lenses. Forget about it... BUT, there is a plan B that works marvelousely: with two polarizers filters mounted one on another (an one inverted), you get the same result, even better because you have full control on the "darkness" of your filter by rotating one of the two filters to adjust the volume of light entering your camera. You find polarizing filter on Ebail for 5 bucks. So this is it. This is a bit tricky to get the light set up proper, and you have to operate a lot manually (which anyway you do if you are serious about touching an SLR). But this is worth it in my opinion.
Here is below the "do it yourself" page. As you will see, this is not rocket science. I encourage you to try, because this is what make the difference (in my view) between SLR video and the rest of the world. Those who are interested can see on my camera the set up next time we meet at the shore. I have equiped my three lenses with that (two of then with the same diameter) and I am still at the start of the learning curve, but guess what, that works! and it is fun.
Joined: 02 Sep 2006 Posts: 5806 Location: Washington, DC
Posted: Thu Mar 24, 2011 9:29 am Post subject:
Good write up JB. I really liked the ND filter that you build.
Another thing that you have to consider when you use your ND is that you have to white balance most of the time your camera plus you have to consider the light temperature you have during the time of the shooting.
You use your ND, you do have to open your lens at least one stop your lens or increase your shutter speed.
Most of the digi and entry level SLRs or video cameras they have these setting in auto.
Joined: 07 Sep 2006 Posts: 699 Location: Washington DC
Posted: Thu Mar 24, 2011 10:37 am Post subject:
Good point I think. As I mentioned, there are several parameters and we have to operate "manual" and all that. So, a lot of things to think about. Most of the nice takes with this technique are made by afficionados in very steady conditions, with time to think and proper setup etc. We often have to move fast and improvise, taking rapid decisions. We also often pan the entire horizon and this (I guess) add a layer of uncertainty (although I am not so sure as white balance is probably dealing with color temperature i.e., sunshine, or clouds etc and this may not vary during a pan). So anyway, the bottom line is that for me for now this remains challenging. But again, leaning curve, work in progress. I will try the "custom" white balance and see if I can handle this additional parameter and I will report how it goes.
See you there.
Best, JB-007 _________________ licensed to kite...
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