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-   -   What is a good deep focus lens? (http://www.dvinfo.net/forum/alternative-imaging-methods/56048-what-good-deep-focus-lens.html)

Leo Mandy December 14th, 2005 11:16 AM

What is a good deep focus lens?
 
I have a 50mm and a 28mm lens, but I would rather have a little deeper of a focus because I find the 50mm use too much sometimes. Any suggestions?

Joel Aaron December 14th, 2005 12:11 PM

Quote:

Originally Posted by Mandy Leo
I have a 50mm and a 28mm lens, but I would rather have a little deeper of a focus because I find the 50mm use too much sometimes. Any suggestions?

The wider a lens is the deeper the DOF appears... so 20mm or wider will increase the DOF. Obviously closing the aperture of any lens down will increase the DOF too. So shooting at F5.6 or F8 on your 28mm should yield more DOF - though you may start to see grain or need to add light.

Some people seem to be having hotspot issues with wider lenses on some adapters.

Bill Porter December 14th, 2005 02:24 PM

How about your camera's stock lens with no adapter?

Leo Mandy December 14th, 2005 02:33 PM

Well, I would use the stock lens, but without the adapter, it is not going to have that nice soft look of film, so in my opinion, it would love like switching from film to DV to film again and that isn't what I want.

Marcus Marchesseault December 14th, 2005 04:55 PM

The only way to accomplish this while using the 35mm adapter is to stop down the 35mm lens. In other words, you need to close the iris on the 35mm lens and will probably have to compensate with greater exposure on the video lens. The smaller the iris, the greater the DOF.

Bill Porter December 14th, 2005 06:11 PM

Marcus, you're right, but so is Joel, and the deal on this one is, a wider lens with bigger aperture, will give a better look (brighter and less grainy) than stopping down another lens.

Joshua Provost December 14th, 2005 06:25 PM

Oh, boy, we have really hit a turning point, haven't we? Now we've got working 35mm adaptors, and people are trying to figure out how to get deeper depth of field. Interesting turn of events.

Joel Aaron December 14th, 2005 11:47 PM

Quote:

Originally Posted by Joshua Provost
Oh, boy, we have really hit a turning point, haven't we? Now we've got working 35mm adaptors, and people are trying to figure out how to get deeper depth of field. Interesting turn of events.

I've actually been on that point since I first started wanting one of these... and it's pretty obviously an issue.

I've got DOF charts... so I figured out pretty fast that shooting at 1.4 on a 50mm gives you... 1 foot or so of focus range at 6ft. That's cutting it really thin. So we see all these bizarre tests of coffee cups... but not too many dolly moves of actors doing anything you typically see in every movie.

Follow focus and 2nd AC are the first things a lot people are going to add to their routine when these things really start taking off. Oh, and a light kit. :-)

Joshua Provost December 15th, 2005 08:42 AM

It's just funny to me, because talking with film cinematographers, getting deeper depth of field is often a concern. Using higher speed stocks, so they can stop down. Using more light, so they can stop down.

Maybe we should be working on 16mm adaptors? Sort of a practical, workable compromise. (Don't worry, I'm kidding!)

Leo Mandy December 16th, 2005 01:48 PM

When I hear that a lens is a good "portrait" lens (some 135mm or 100mm), what does that mean exactly?!?!

Quinn OConnell December 16th, 2005 04:13 PM

My guess would mean that the the focus is primarly on the face.. generally speaking the higher the zoom the more backround blur you will see - selective focus.

i have just got a 135mm lense and the blur ( bokeh?) is alot more extreme than say a 50mm or 85mm at the same distance from the subject.

i am about to post footage from this lense with the Letus35A..

Joel Aaron December 16th, 2005 04:51 PM

Quote:

Originally Posted by Mandy Leo
When I hear that a lens is a good "portrait" lens (some 135mm or 100mm), what does that mean exactly?!?!

Usually means a combination of characteristics including focal length, quality of bokeh (type of blur compared to other lenses of the same focal length), contrast etc.

Portrait lenses have even shallower DOF than a 50... so if you shoot them wide open they'll have a few inches of focus. The hair on the back of the head is already blurring if you're focused on the closest eye to the camera. Great for still shots or closeups of an actor... who's not moving.

John Colette December 16th, 2005 05:21 PM

Get an 80mm 1.4. that'll do it. And a longer 135mm 1.8 prime.

Marco Polimeni December 16th, 2005 06:14 PM

This is my first post on this forum.

Another way to keep under control the DOF is to set the hyperfocal distance using the DOF scale on the lens.

On my Nikon 50mm if I set the diaphram at f11 and the distance on 6m everything betoween 3,7m and Inf. will be sharp.

More about hyperfocal distance here

http://www.dofmaster.com/hyperfocal.html

Bill Porter December 17th, 2005 12:07 AM

Quote:

Originally Posted by Joel Aaron
Portrait lenses have even shallower DOF than a 50

Depends on the 50mm and the portrait lens you're comparing!

You're right about everything else though. And Mandy, the reason they are called portrait lenses is, the closer you get to the subject, the more prominent and distorted the nose (and if you get close enough, everything else) appears. So, most "portrait" lenses are 80-135mm and beyond.


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