Shallow Depth of Field without adapter?

[Michael Palmer]

Pasha
If they had a fix by now I wouldn't care as this company treated me like dirt.
The image quality was completely unacceptable.

I did rent this m-2 once for my V1U and it was acceptable for that camera, however it took some time to fine tune it to the camera. I spent countless hours trying to adjust it for the EX1 and I was finally told it just won't get any better by RRM.

[Pasha Hanover]

That's unfortunate about their customer service. The impression I got from their site is that they cater and want to help the "indie". I was planning on buying a full system with mattebox, rails and all and all from them. I don't want to flush $2500 down the toilet if it ends up looking bad and with no support from them to try and fix it. :-( So now I don't know...

[Simon Wyndham]

Why keep trying for short depth of field? Films in days gone by strived for deep depth of field. Watch films such as Lawrence of Arabia for example. In fact even more modern films such as Terminator 2 aimed for a long depth of field.

Use your tools and make them work for you.

On a technical level zooming in does *not* reduce depth of field. Depth of field is purely the result of iris setting and sensor size. All zooming in does is show you the differential in focus that is in the picture anyway, but that the resolution of the picture cannot show/discern when it is fully wide.

[Bill Ravens]

Originally Posted by Simon Wyndham

All zooming in does is show you the differential in focus that is in the picture anyway, but that the resolution of the picture cannot show/discern when it is fully wide.

I would disagree. The DOF is determined by the subject distance (that is, the distance to the plane that is perfectly in focus), the lens focal length, and the lens f-number (relative aperture). Hence, shallowness of focus is directly related to the focal length(or zoom ratio). This is well known optical physics.

[Simon Wyndham]

Hence, shallowness of focus is directly related to the focal length(or zoom ratio). This is well known optical physics.

No, focal length will only show you the effects of the f-stop setting and sensor size. You cannot change depth of field from a straight up technical standpoint by increasing focal length.

[Chris Leong]

Hi All

I just finished principal photography on my short dramatic film "5150". I had a skeleton crew and three excellent, professional actors for half a day.

So even though I own a Letus Elite and the whole complement of stills lenses, I elected to shoot the piece without a DOF adaptor.

You can see the first, untimed rough cut of the piece here:
Director's Sample - "5150" - Rough Cut By Chris Ross Leong On ExposureRoom

I do have a fine cut, timed, colored and film effected, and it will go up onto exposureroom when the site is back online (they're upgrading the site now).

You can see that I've staged a lot of the headshots with deep backgrounds to direct the viewer's eye accordingly, and not many people can tell if I used a DOF adaptor or not.

I'd say that the DOF adaptor works much better indoors or in situations where there isn't a lot of depth in the subject matter (i.e. not a lot of distance between the subject and the background) - the video-ness of the camera shows up much more in a shallow shot.

Mainly the reason to leave the Letus behind was that I didn't have a pro focus puller on board and I had to concentrate on the direction of the piece. Also, my camera operator was new to the EX1 and so had to struggle to master that, his hands were already full trying to deal with the lens in manual focus while hand holding.

Second, we were going with existing light in a very short winter's day. So there was a lot of fiddling with camera settings to get the entire piece shot at a consistent T stop, T3. If I had the Letus/ZF setup with me, that would have meant a bunch of ND 4x56's flying in and out of the matte box each shot. Doable with a pro camera crew, or even a semi-trained crew. I had neither for this shoot.

Finally, we were shooting in a bad part of town. I didn't have any extra bodies to watch the equipment cases while we were shooting, and no way was I going to risk my prime lens case out there alone in the back of a car.

FYI, we got 105 shots off in the 4 hour shoot, around 80 were usable, and 65 of those are in the rough cut.

On topic, I've been in on the DOF deal from the very beginnings here in the DIY section, have built my own, have owned or operated nearly all of them at one time or another, settled on one of the first Extremes, now have the Elite BF adaptor on it. I'm sure others work, just not as well, IMO. But, as has been mentioned above, it's a real package to handle alone, especially with 12 lenses and a matte box, and quick release adaptors to go off and on tripods, etc. I'd say it needed a lot more handling than, say my Aaton S16 camera.

HTH
Cheers
Chris

[Bill Ravens]

I stand corrected. However, I will say that the apparent DOF changes. In the end of things, when the viewer sees the images, selective attention is placed on the plane of highest apparent focus. So, technical myth or not, higher zoom ratios appear to decrease the DOF. And the intent of manipulating the plane of attention is achieved.

[Brooks Graham]

Originally Posted by Bill Ravens

I stand corrected. However, I will say that the apparent DOF changes. In the end of things, when the viewer sees the images, selective attention is placed on the plane of highest apparent focus. So, technical myth or not, higher zoom ratios appear to decrease the DOF. And the intent of manipulating the plane of attention is achieved.

Hmmm. Interesting topic as I did a simple test a couple of days ago to record the apparent DoF changes at different lengths on the EX3 as compared with an FX1. The link below is a QT of the EX3 on a DSC backfocus chart placed 10 feet from the camera and another five feet behind it. Started at Z99 backing off slowly with pauses at Z75, Z50, and Z25. It really looks like DoF changes to me. Apparently.

Oh, and yes it was shot outdoors in the frigid winter weather... ;-)

http://idisk.mac.com/brooksgraham-Pu....264-25pct.mov

Thoughts?

[Brooks Graham]

I did the same experiment as the author of the article cited in a previous post, isolating parts of the image, and it's more than just an apparent illusion. This looks exactly like a changing DoF to me.

And to be clear: the f-stop was held constant as was the sensor size

[Peter Wright]

Yes, I must admit, I was interested but not totally convinced by Walter Graf's article - firstly, if the background is perceived as softer, it IS softer as far as I'm concerned, and in the part where he posted two close ups of a blue ball on a shelf behind the subject to show they were the same - to my eyes the right hand one is clearly softer.

[Bill Ravens]

I agree with you guys, however, I think the point Simon was wanting to make is that zoom/tele lenses don't, TECHNICALLY speaking, create a more shallow DOF. It only looks like it. DOF is a very specific phenomenon in the physics of optics that can be calculated. Using a higher zoom factor with the math that describes DOF, will not show a change in DOf

And my point is, that's good enough for me to use a zoom/tele for shallow DOF, if appropriate for the scene.

[Ted OMalley]

Hmmm. Okay. So, then, perhaps what Simon is saying is not contradictory to the following statements:

1. If you are after a very shallow depth of field look as can be achieved with 35mm cameras but without a 35mm adapter, zoom can be a very useful tool (if you have the space).

2. Zoom, in conjunction with Iris, can provide a final product in which the background and foreground focal planes are quite far apart - much more than using Iris alone.

3. Shooting full wide will expand the focal plane to such a degree that even when shooting with the Iris fully open, separation between foreground and background is minimal.

4. The camera's Depth of Field indicator (accessible by the Lens Info button, by default) displays a scale in either feet or meters. At full Iris (1.9) and with the lens fully wide (5.8), the focal plane indicator is wide enough to cover the entire scale (1 to infinity). Zoomed only to 10, the indicator is reduced to 1.5 meters. At 15, the indicator covers only a half a meter. Between 25 and 81.2, the indicator is even smaller and reduces in size, but to such an extent that it is difficult to attach a number to it based on eyeballing the scale.

5. While zoomed, I can shoot "through" a chain link fence in such a way that the fence is all but invisible. At full wide, without changing any other settings, that fence might be out of focus, but appears solid. It appears to me that there is more going on than simply a "differential in focus that is in the picture anyway, but that the resolution of the picture cannot show/discern..."

It is my opinion that zooming does affect the DoF. I might be wrong, but actual testing this morning has me convinced otherwise.

[Bill Ravens]

One thing to remember is that most zooms change the effective aperture(by a small amount) when you change zoom settings. This effect has to be accounted as aperture change, not zoom change.

[Simon Wyndham]

Originally Posted by Ted OMalley

Hmmm. Okay. So, then, perhaps what Simon is saying is not contradictory to the following statements:

1. If you are after a very shallow depth of field look as can be achieved with 35mm cameras but without a 35mm adapter, zoom can be a very useful tool (if you have the space).

Yes, it can help. What I was saying was that zoom doesn't actually change the depth of field, however it does enhance the 'effect' of it because you are effectively enlarging the background, which if not technically in focus in the first place will look even more blurred when you zoom in.

Originally Posted by Ted OMalley

2. Zoom, in conjunction with Iris, can provide a final product in which the background and foreground focal planes are quite far apart - much more than using Iris alone.

Remember that when you zoom all you are doing is enlarging the background, which is out of focus anyway even though you can't see it fully wide. The trouble with zooming is that you actually make the background appear closer to your subject effectively 'compressing' the distance between them. So overuse of the technique can make things a bit claustrophobic. Iris creates the DOF, zoom just amplifies the effect.

Originally Posted by Ted OMalley

3. Shooting full wide will expand the focal plane to such a degree that even when shooting with the Iris fully open, separation between foreground and background is minimal.

I think this is more to do with resolution. If you are fully wide (depending on the lens of course) the background could still appear soft if your iris is fully open and your recording system and display was of high enough resolution.

If you zoom in to focus on an actor in, say, a forest location, or a beach, so that your background is out of focus and the actor is in focus, then you zoom back out to fully wide, your background is still out of focus even though you cannot see the effect due to the limits of resolution. What you are now seeing on the monitor is like taking a soft out of focus photograph and reducing it to a small size in Photoshop. Because the picture is now not of very high resolution it looks perfectly okay, even though in reality we know the picture is not sharp.

Originally Posted by Ted OMalley

"differential in focus that is in the picture anyway, but that the resolution of the picture cannot show/discern..."

Exactly.

Originally Posted by Ted OMalley

It is my opinion that zooming does affect the DoF.

There are no if's but's, why's or maybe's. The actual DOF is not affected. It is only an illusion of DOF.

[Ted OMalley]

Bill,

I watched the Iris ring and the 1.9 in the viewfinder. Neither 'appear' to change. Are you saying that there is a "behind the scenes" change?

I would have to say that the highlights look slightly dimmer as I zoom in, is this the aperture change you are referring to, or some other optical effect?

If the aperture is secretly and 'unreportedly' closing as I zoom, accounting for the darkening highlights, then it would be increasing the depth of field, rather than reducing it. However, you seem to be indicating that the increased depth of field effect is actually assisted by the covertly changing iris.

Please elaborate.

Thanks,