Red Vs Viper

[Paris Remillard]

Um... Stephen was saying DOF was determined by the resolution of the lens and the imaging system, which it's mostly not. (This does have some marginal impact, as it determines what counts as acceptable focus.)

As to the argument that varying focal length while maintaining subject size doesn't impact DOF, I've presented it here (or, actually, I think over at DVXUser) previously. I've thought about it since then, and decided that whether or not it's true is largely semantics.

Using a wider lens exaggerates perspective, which causes background objects to look smaller. Because they look smaller, they also look sharper. This results in them appearing to be more in focus.

I was referring to Stephen saying, "I maintain DOF is determined by stop & image size only."

The rest of what you said is exactly what I said in my previous post.

 

[Ketch Rossi]

Hi Ketch,

I find -23 green with XnView (a free programme) removes the color cast.

After Effects is just as easy, just not free!

Stephen

Hi Stephen,

there is many options with the Viper workflow in color correction, the problem remains the cost of recording, transfering to a powerfull in off system to have the capacity for it, and there for the choice from my view point remains the RedOne, workflow is much important then some people are let to believe, you definitely do not want to find your self in the position of not having in off money to post your shots.

Thanks for pointing out the options do, just I fill strongly about Jim's project and I do not think I will be neding the softwere for the Viper.

Ciao,

KETCH ROSSI

 

[Stephen Williams]

Using a wider lens exaggerates perspective, which causes background objects to look smaller. Because they look smaller, they also look sharper. This results in them appearing to be more in focus.

Hi Chris,

If you enlarge the background image from the wide lens to the same size as it was with the longer lens you will find it to be equally soft. You have not increased DOF at all.

Stephen

 

[Brook Willard]

He was only referring to appearance, not actual DOF.

 

[Tom Lowe]

A couple things I'm still not clear on.

Stephen is saying focal length does not affect DOF. But it seems that the larger your sensor, the longer focal length you need to get a similar FOV. And the longer focal length gives you a more shallow DOF, right?

Here is what wikipedia says:

The image format size also will affect the depth of field. The larger the format size, the longer a lens will need to be to capture the same framing as a smaller format. In motion pictures, for example, a frame with a 12 degree horizontal field of view will require a 50 mm lens on 16 mm film, a 100 mm lens on 35 mm film, and a 250 mm lens on 65 mm film. Conversely, using the same focal length lens with each of these formats will yield a progressively wider image as the film format gets larger: a 50 mm lens has a horizontal field of view of 12 degrees on 16 mm film, 23.6 degrees on 35 mm film, and 55.6 degrees on 65 mm film. What this all means is that because the larger formats require longer lenses than the smaller ones, they will accordingly have a smaller depth of field. Therefore, compensations in exposure, framing, or subject distance need to be made in order to make one format look like it was filmed in another format.

....

The image format size also will affect the depth of field. The larger the format size, the longer a lens will need to be to capture the same framing as a smaller format. In motion pictures, for example, a frame with a 12 degree horizontal field of view will require a 50 mm lens on 16 mm film, a 100 mm lens on 35 mm film, and a 250 mm lens on 65 mm film. Conversely, using the same focal length lens with each of these formats will yield a progressively wider image as the film format gets larger: a 50 mm lens has a horizontal field of view of 12 degrees on 16 mm film, 23.6 degrees on 35 mm film, and 55.6 degrees on 65 mm film. What this all means is that because the larger formats require longer lenses than the smaller ones, they will accordingly have a smaller depth of field. Therefore, compensations in exposure, framing, or subject distance need to be made in order to make one format look like it was filmed in another format.

http://en.wikipedia.org/wiki/Depth_of_field

So it seems that focal length does have an effect on depth of field, as we all assume. When Stephan said "Focal length does not effect DOF, just F stop and image magnification at the sensor"... what is he talking about?

BTW, what is the image sensor size of the Viper vs the Red?

 

[Brook Willard]

Stephen was referring to focal length not having an effect on DOF in only one particular scenario: where the subject distance is increased to maintain the same framing. For example:

50mm lens @ 25' subject distance.
100mm lens @ 50' subject distance.

These two would have the same DOF. This is what he meant when he said that focal length has no effect... just to debunk that whole "back up and zoom in" myth. But if focal length is the only factor that changes, yes, DOF will be affected. If multiple factors [the three factors are focal length, stop and subject distance] are changed in complementary ways [such as in the example above], DOF will not change.

 

[Tom Lowe]

Got it. And what about the Viper sensor size? What types of lenses can be used with it?

It also seems that the Viper cannot overcrank over 30p?

 

[BLUESPIDER]

How does the Dasla compared to the RED?

 

[Johan Lindgren]

The viper uses 2/3 B4 mount video lenses. The DigiPrimes from Zeiss/Bandpro seems to be the best ones out there.

Overcrank issues depend heavily on how you record your.

 

[Chris Kenny]

If you enlarge the background image from the wide lens to the same size as it was with the longer lens you will find it to be equally soft.

Yes, I know.

You have not increased DOF at all.

Assuming you're still standing at the same distance from your subject, you have increased the depth of the area that appears to be in acceptable focus; that's all DOF measures. You as the cinematographer should be aware that you've "paid" for this by shrinking things, of course.

 

[Babu Kantamneni]

10 million budget

10 million budget

12 pages of discusion about 10 million budget film
by
Phil maker
filmaker!