depth of filed trouble

[krassi]

hi there!
im trying to get some nice depth of field with a vray cam and it is not working like i want it.. i try to get a strong blur in the front and in the distance.. but whatever i tried (and im checking it in vray-rt) like super tele with low f-stop number .. its not really what i want..

i could use the z-depth with a compositing soft but it mostly looks like blured sh.. hmm are ther any plugins or other things that rock ?

thanks in advance.. daniel

heres a crappy picture of the szene.. a very large building

[rivoli]

in a shot like that you'll never get a shallow dof like the one you're after. if you did, it'd look like a miniature building and not an actual one.
to keep it consistent with how the phys cam work, you might drastically change the scale of the scene, turning the building into a small model. that way it should work, but it would look totally unrealistic..

[dlparisi]

What Rivoli said is true.... Use http://www.dofmaster.com/dofjs.html to compute some basic distances and you'll see it's nearly impossible, even with an f/1 aperture, to get any noticeable depth of field on a scene of this size. I'd recommend faking it - you can use photoshop lens blur for OK results or richard rosenman's DOF generator pro for some better results. What composting program are you using?

[3DMK]

as the guys said....in a real life situation ...with a standard 35mm FILM GATE camera....you wouldn't get much DOF at all.
The way to increase it without having to re-scale a scene is to change your film gate parameter to a larger value. You will notice that changing the film gate to a larger value also increases the Field-of-View so you will need to adjust that to suit.

Hope this helps

[RE:FORM_STUDIOS]

You guys are forgetting about tilt/shift lenses

I did some experiments a while back and I could be wrong, but if I remember correctly, the vray camera does a good job of replicating the effect if you use the perspective correction along with your DOF settings...

I could be wrong ofcourse... but in real life, if you wanted strong DOF on a scene of that scale, you would use a tilt/shift lens.

I take it you've all seen those short films / adverts doing the rounds that uses this technique to make timelapse scenes appear like miniatures?

[rivoli]

you're right, won't be what you would expect from a shot like that, but it may be very cool if achieved directly with a vray cam. could be very easily done in post, but I can imagine the great nerdy satisfaction of doing that in 3d. I'm so going to try that

[krassi]

THANKS for all the advice.. well its physically not possible to get some hardcore dof with this cameraposition and lens settings.. i got good fake results with z-buffer and photoshop..
i tried something like this with my dslr and so its not realistic.. but a lil dof blur the unimportant crap in the background. together with some vray fog it looks good..

ill post some pics of the final ones. got 2 other perspektives were dof really rocks

thanks and seeeya

[3DMK]

rivoli's

you're right, won't be what you would expect from a shot like that, but it may be very cool if achieved directly with a vray cam. could be very easily done in post, but I can imagine the great nerdy satisfaction of doing that in 3d. I'm so going to try that

As I mentioned befor -IT CAN BE DONE IN 3D with Vray Physcam.

Simply increase the standard 35mm FILM GATE -When increasing the film gate [to say 70mm as in cinematic cameras] you will see the field of view get much wider.
Then simply increase your focal length to reduce the field of view back to what you had it before. As you do this process you will see your DOF decrease giving you more blur...try it!!! IT works straight in Vray without having to do any fake DOF processing after.

Cheers

[Da_elf]

isnt 70mm imax?

[3DMK]

Da_elf isnt 70mm imax?

Not quite sure but it's something around that. There is some good stuff on Wikipedia about particular film formats with technical info such as film gate,etc

[rivoli]

As I mentioned befor -IT CAN BE DONE IN 3D with Vray Physcam.

yes, you're right, but I was thinking about doing that with tilt lenses. I guess it may be more fun to try and replicate that, rather than increasing the film gate. just for the sake of it

[Da_elf]

was just confused when you said 70mm was standard cinimatic when 35mm is the standard. although my guess is things will slowly change just how 8mm and 16 were pretty standard at one point

[Tommy L]

From an efficiency point of view (render speed and control-ability) I would do it in post. DOFpro which was mentioned earlier is fantastic. But I would stand by the earlier assumptions that it will indeed look shit. It will look like a miniature.

[raymarcher]

Yes, I think a 70 mm film gate equals the film back of an imax horizontal pulldown 15 perf format, a 70mm vertical pulldown 5 perf format uses aprox a 52.47mm horizontal aperture

not sure though