Mathew Collins
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Posts posted by Mathew Collins
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Hi,
Is there any distance measurement equipment available to help
focus puller to know the distance to subject?
Please share your inputs.
-Mathew Collins.
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matthew think of it this way.
theoretically (for lack of better term) sensor size has no effect on dof
practically, however, it very much does
say you have a lens on a 16mm camera
then mount that lens to a 8x10 camera, or project it onto a 111'x32' plane
what happens to dof in those cases? nothing happens. it remains the same
but, practically speaking, there is no sense using a 16mm lens on larger formats, you will just get vignetting.
so you use a longer lens, or one that covers the larger format, and as a result, you end up with less dof.
Just comparing this with David Mullen quoted on Jun 18th,
"A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure."
Can i put it in this way?
If i am planning to project an image which is shot in 16mm onto 70mm format, image being enlarged so we would use use small circle of confusion while shooting in 16mm.
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Thank you David and Brian. I am trying to understand it.
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"Critical" is a common English word.
Here it means smaller.
Does that mean 'small Circle of Confusion figure'?
But my understanding was 'critical=urgent'.
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Thank you David.
My question is not 'What is circle of confusion?' but 'more critical Circle of Confusion figure'
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Imagine that you're framing up the EXACT same image with two separate formats, the first version is with a 50mm on a S35mm sensor at T/2.8, and the second is with a 25mm on a S16mm sensor at T/2.8.
The composition of your images is identical, but the S16mm image has a deeper depth of field because (in order to achieve the equivalent field of view) you're using a wider lens.
Thank you Mark.
What is the meaning of "so you have to use a more critical Circle of Confusion figure"?
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Not just focal length, f-stop and distance focused affect depth of field, but also the Circle of Confusion figure used. A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure.
However in general larger formats have less depth of field when you match field of view, f-stop, distance focused to a smaller format because you have to use a longer focal length on the larger format to achieve the same field of view as the smaller format.
> A 25mm at f/2.8 focused at 5 feet, let's say, has a different depth of field on a smaller format because if shown on the same sized screen as a larger format, the image is being enlarged more so you have to use a more critical Circle of Confusion figure.
Not able to understand the this part.
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While sensor size/film gauge affects your DoF, there are of course other factors to what affects it - distance from the subject, t or f stop, focal length, light & composition. But then your t or f stop is affected by you cameras/film ISO.
But the wikipedia page can help explain it a lot about DoF for you: https://en.wikipedia.org/wiki/Depth_of_field
Thank you Dan.
I am aware of the factors distance from the subject, t or f stop, focal length, light & composition.
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Adding to the above question,
a document "Sensor Size and Field of View of the Primo 70 Series of Lenses" in the following link says,
http://panalab.panavision.com/panalab-reference-library?page=4&title=&field_document_tags_tid[0]=228
Sensor size has no effect on the depth of field. A 21mm at T2.8 will always be a 21mm at T2.8, whether it’s on a 70mm camera, a Red Dragon, or a Super 35 camera. However a 27 mm on a Red Dragon will give you the same Field of View as a 21 mm on Super 35, and using a longer lens gives you less depth of field.
So at the same camera position and with the same framing, a filmmaker will get less depth of field on a Red Dragon than on Super35, but only because he has to use a longer lens.
Please provide your views.
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Hi,
Is there any relationship between Sensor/Film size and depth of field?
The following video says, Sensor size has an effect on the depth of field.
-Mathew Collins.
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Thank you David, Adam.
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Compared to what? All formats crop the projected lens image since it's a circle and most aspect ratios are rectangles. So when you say "loss of field of view" what is your frame of reference for a "normal" field of view? 3-perf Super-35? A 24mm wide gate?
I missed '4-perf 35mm/ Super-35'.
While using spherical lens on the cameras like F65, Red Dragon, Does the loss of field of view exists compared to 4-perf 35mm/ Super-35?
Only RED WEAPON 8K VV(VistaVision Dragon Sensor) - 33.60 mm x 21.60 mm
and RED WEAPON 8K VV Ana(Anamorphic) - 33.60 mm x 21.60 mm having height of the sensor greater than 18.59mm.
Does the height comparison of the sensor with 4-perf 35mm is relevant only when shooting in anamorphic?
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On the Sony F65, the sensor is 24.7mm x 13.1mm. So if your maximum sensor height is 13.1mm instead of 18.59mm, then you'd be cropping the sides of the sensor to get a 1.20 : 1 area that when expanded by 2X horizontally becomes 2.40 : 1 because you are using 2X anamorphic lenses. If you do that math, that's an effective 15.72mm x 13.1mm area of the sensor. You'd lose some field of view so your lenses would be a bit more telephoto unless you used shorter focal lengths to compensate.
While using spherical lens on the cameras like F65, Red Dragon, Does the loss of field of view exists?
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Thank you David, Satsuki.
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Sure you can but what's the point? Hawk already makes 1.3X anamorphic lenses for Super-35 sensors so what would be the advantage of using their 1.3X anamorphic lenses made to cover a larger sensor?
In the above link DP Markus Fördere is testing HAWK65 Anamorphic Lenses on RED Weapon 8K.
Red Weapon is in 2-3 models like HELIUM® 8K Super35, RED DRAGON® 8K VV™ as well as VV Anamorphic
Would he using the any of the 2nd or 3rd model?
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Hi,
Is it possible to use lens designed for 65mm cameras on super 35 cameras?
Got this questions while going thru the following link.
Please share your inputs.
-Mathew Collins
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Thank you David.
Red Epic MX image circle is 31.4mm and
Zeiss Ultra Primes 16mm Image Circle is 33mm.
I think the sensor would fit inside the image circle.
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Hi,
Would that vignetting will be visible in the Camera LCD screen or while looking thru view finder?
Now I remember one issue came up while assisting a DP in the last movie. We were using Red Epic MX and
Arri Ultraprime lenses.
DP asked camera assistant to change the lens into 16mm and he encountered some issues with the lens. But not sure the issue is about vignetting. I think after that he did not use that lens. We were shooting in 2.4:1.
The following link says, "S35 Mysterium-X sensor is 30mm x 15mm. So to cover the entire sensor, you would need an image circle of 33.54mm or call it 34mm.".
I am not able to find out the diameter of the image circle formed by Arri Ultraprime 16mm.
http://www.reduser.net/forum/showthread.php?41080-Definite-Image-Circle-Size-for-Epic-5K-Sensor
Would the image circle of Arri Ultraprime 16mm cover Red Epic MX?
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Thank you David, Michael.
As David pointed out, I was confused with 35mm format and Ø 35 mm.
Again that opened bunch of new knowledge.
Thanks much.
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Thank you D
An extender increases the focal length and also increases the image circle diameter.
Academy is the old 35mm format standard, Super 35 Is a little wider.
Probably as some sort of arse-covering exercise Angenieux are labelling their 24-290 as an Academy zoom because at the wide end the image circle gets down to 30mm in diameter, but in practice all those Angenieux zooms cover S35, since the full camera aperture is always cropped in a bit, and most digital sensors that are labelled S35 will be covered by a 30mm diameter image circle. All Alexa formats except Open Gate are under 30mm diagonal for example. 24-290 zooms have been used on countless S35 film and digital productions.
Optimo extenders will increase the image circles of those zooms to at least a 35mm diameter, which is enough to cover Alexa Open Gate and the larger Red sensor formats.Thank you Dom.
>Optimo extenders will increase the image circles of those zooms to at least a 35mm diameter.
In this case is 35mm is bigger than Super-35?
For all the lenses by adding an extender Super-35+ expands to Ø 35 mm.
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Hi,
I was just going thru some lens specifications in the following links and confused.
OPTIMO SPHERICAL LENS 15‑40mm says,
https://www.angenieux.com/optimo-compact-lens-zoom-15-40/
Lens specification gives,
IMAGE COVERAGE: S35+: 31.4 mm diagonal
Image coverage: S35+ (Ø 31.4 mm), expanded to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)
OPTIMO SPHERICAL LENS 28‑76mm
https://www.angenieux.com/optimo-compact-lens-zoom-28-76/
IMAGE COVERAGE: S35+ 31.4 mm diagonal
Image coverage: S35+ (Ø 31.4 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)
OPTIMO SPHERICAL LENS 45‑120mm
https://www.angenieux.com/optimo-compact-lens-zoom-45-120/
IMAGE COVERAGE: S35+: 31.4mm diagonal
Image coverage: S35+ (Ø 33.34 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)
OPTIMO SPHERICAL LENS 24‑290mm
https://www.angenieux.com/optimo-long-lens-zoom-24-290/
IMAGE COVERAGE: 35 mm academy – 30 mm diagonal
With extenders, image coverage becomes S35+ - 31.4 mm diagonal
Image coverage up to S35-3 perf. (Ø 30 mm), expands to Ø 35 mm when used with Optimo extenders (more info in DOWNLOAD section)
1. Does the corresponding focal length increases while adding an extender?
2. Does the image coverage decreases by adding and extender?
3. What is the difference between S35 an S35+ ?
4. Is S35+ bigger than 35mm academy?
5. Why the image coverage of 45‑120mm on S35 is 33.34 mm and others 31.4 mm?
6. By adding extender to some lenses 35mm academy changes into s35+ and vice-versa? How?
7. By adding an extender on 15‑40mm or 28‑76mm or 45‑120mm, S35+ changes to 35mm academy
but for 24‑290mm 35mm academy to S35+?
Please share your thoughts.
-Mathew Collins.
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Thank you David, Satsuki and Adam.
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Usually, if you're using a really light diffusion, it's because you don't have enough light output to use something heavier. So in that case, moving the light further away won't work because you'll lose intensity too. Or it might be an issue of available space.
Mainly though, because you're seeing more of the hard light source through the frame directly, you would have to back the light up really far away to minimize hotspot, at which point it's not worth it because you've lost so much output.
Remember, light diffusion material is like a thin wisp of clouds under the sun. You can still see the sun through it, which means the cloud is not diffusing the light very much. Imagine how far away and small the sun would have to be in order to barely be visible through that thin cloud. If you were trying to get soft even light, wouldn't it be simpler to just have thicker clouds? That's how diffusion works.
>Usually, if you're using a really light diffusion, it's because you don't have enough light output to use something heavier.
Where would be the use of light diffusion ? upto 1KW lights? Above that heavy diffusion?
Is there any approximation?
Any light diffusion (say 251, 252 or 452) is required to attach to Kinos(say 4 bank) to provide
light diffusion and make 4 tubes into a single source?
Distance measurement equipment
in General Discussion
Posted · Edited by Mathew Collins
Ultra-sonic is from any specific company? Any issues with Disto in lowlight conditions?