BMC + Pocket as a set

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Margus Voll

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BMC + Pocket as a set

PostFri May 24, 2013 11:04 am

I wonder if it would be viable setup to have
pocket version for wider stuff ?

I may be getting wrong the FOV calculation or crop on pocket model but
for a moment it seemed to me as it has less crop and could go wider?

Then if so one could combine those 2 cameras to have all covered.
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Thomas Schumacher

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Re: BMC + Pocket as a set

PostFri May 24, 2013 11:19 am

Margus,

you got something wrong here: crop on BMC is 2,4 and the crop on the pocket cam is 3,0 - so it's even more difficult go get wide shots with the pocket unfortunately.

I thought about the same team and then would have tried some small gimbal-stabilized system for the pocket to make it my "steadycam", but the question how to get wide on the pocket was already adressed somewhere here.

EDIT: here it is: viewtopic.php?f=2&t=8348
https://www.gernemehrfilm.de/
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Margus Voll

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Re: BMC + Pocket as a set

PostFri May 24, 2013 11:23 am

Ok then i'm confused about the 1.3 number floating a round then ?
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Thomas Schumacher

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Re: BMC + Pocket as a set

PostFri May 24, 2013 12:11 pm

People often like to put crop-factors in relation to APS-C sensors e.g., so then the crop-factor is a bit less than if you put in relation to full-frame, but this is a bit pointless in terms of lens-choice, as on every lens, even the EF-S ones for the APS-C sensor, their focal length is stated in full frame-terms, so the Tokina 11-16 would have the 11-16mm on a full frame, not on an APS-C sensor, where it's more like a 17,6 to 25,6.
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adamroberts

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Re: BMC + Pocket as a set

PostFri May 24, 2013 12:26 pm

Correction: Focal length is not stated in FF terms. Focal length is an independent measurement that has nothing to do with the sensor size.

The term "crop factor" first came into popular use when DSLRs started to become popular. People who were moving from 35mm DSLRs understood what a lens's FOV looked like on 35mm film but the early DSLR sensors were smaller than 35mm film so to help the manufacturers gave out crop factor info.

No matter what camera you use a 24mm lens, its still a 24mm lens. It's field of view might change (or get cropped) by different sensor sizes.

Generally crop factor is quoted based on 35mm FF. If you have never shot on a FF camera that means nothing as you have no point of reference. So having a crop factor based on what you are familiar with can be useful.

Eg: if you shoot on ASPC with a 17-55mm lens and love the FOV of the 17mm you would look for a lens that is about 11 or 12mm. See the crop factor in this case is not 3 but closer to 1.2.
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Margus Voll

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Re: BMC + Pocket as a set

PostFri May 24, 2013 1:08 pm

Ok then some 8 mm on pocket 1.3 factor is around 10-11 so it should work on paper as pretty wide.

I do not have any ff so i do not care about that so much. FOV is what interests me.

FOV was also my first reference point to think of.
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Thomas Schumacher

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Re: BMC + Pocket as a set

PostFri May 24, 2013 1:39 pm

No, Margus, the other way round: 8mm lens has a fov of 8mm on a full frame sensor, it has a fov of about 13mm on APS-C-sensors like the 7D, about 19 mm on the BMC EF and 24 mm on the pocket cam.
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adamroberts

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Re: BMC + Pocket as a set

PostFri May 24, 2013 1:41 pm

Yeah 8mm would give you a similar FOV as about 11mm (correction, it would be closer to 14mm) on a ASP-C or Super 35mm camera.

That's pretty wide for film.
Last edited by adamroberts on Fri May 24, 2013 1:59 pm, edited 1 time in total.
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Margus Voll

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Re: BMC + Pocket as a set

PostFri May 24, 2013 1:46 pm

So in that sense it would work out as wide cam in pair with regular BMC 2,5 k but in 1080p.

That sounds good on paper.

Have to order pocket one to play around :D

Most of the time we shoot adverts no one goes down from 24 or even 35 mm so it all seems really good.

And as "cheap" b cam it will be handy to sit in the pocket until needed lets say twice a year.

Sounds like a plan to me.
Margus Voll, C.S.I.

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adamroberts

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Re: BMC + Pocket as a set

PostFri May 24, 2013 1:49 pm

This should help solve the issue:
http://www.abelcine.com/fov/

Compare what you know with what you want to know. :-)
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Margus Voll

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Re: BMC + Pocket as a set

PostFri May 24, 2013 2:00 pm

Yes this is all relative and FOV is that counts.

All mm stuff seems confusing :D

I have used some 3D apps and there all the parameters start with FOV on camera.
You have mm also but it is considered more like reference.

It seems the same here also.
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rick.lang

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Re: BMC + Pocket as a set

PostFri May 24, 2013 3:38 pm

Margus Voll wrote:Ok then i'm confused about the 1.3 number floating a round then ?


The crop factor of 1.3x mentioned by BMD reps at NAB2013 was in relation to the lenses for micro four thirds camera I believe. These interviewers seldom seem to pay close attention to what the interviewee says as that number should have been clarified.

And to restate a previous post, when BMD verbally talks about their other new camera, the BMPC4K, having a 35mm film sensor, they do not mean Super35mm film, they do mean the Academy format for 35mm film which is a little smaller. The size of the sensor on the BMPC4K is virtually identical to the Academy 35mm film format normalizes to a 16:9 aspect ratio.

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Re: BMC + Pocket as a set

PostFri May 24, 2013 4:21 pm

Margus Voll wrote:Yes this is all relative and FOV is that counts.

All mm stuff seems confusing :D

I have used some 3D apps and there all the parameters start with FOV on camera.
You have mm also but it is considered more like reference.

It seems the same here also.


I have lost track of what field of view you would like to have on the BMPCC stated in either angle of view (horizontal or diagonal) or the widest lens you plan to but on the BMPCC. Lets assume you mount an 8mm lens on the BMPCC for purposes of illustration. Here are approximate comparative horizontal and diagonal angles of view calculated from sensor sizes all normalized to a 16:9 aspect ratio and the nearest equivalent focal length of a lens on those other sensors giving about the same AOV:

BMPCC 75.9 degrees H, 83.7 degrees D, 8mm lens
BMCC 76.7 degrees H, 84.4 degrees D, 10mm lens
BMPC4K (and Academy 35mm film) 74.1 degrees H, 81.7 degrees D, 14mm lens
Super35mm film 75.8 degrees H, 83.5 degrees D,16mm lens
Full frame 135 stills camera 73.7 degrees H, 81.4 degrees D, 24mm lens

A normal field of view on these different sensors would be provided by the following roughly equivalent lenses on sensors normalized to a 16:9 aspect ratio:

FF 50mm, about 44.9 degree diagonal AOV

S35 35mm, about 44.4 degree diagonal AOV

BMPC4K 30mm, about 44.0 degree diagonal AOV - typically people will use a 35mm lens with an AOV of 38.2 degrees since there are only a few 30mm lenses available

BMCC 22mm, about 44.8 degree diagonal AOV - typically people will use a 24mm lens with a AOV of 41.4 degrees since there are no 22mm lenses available; a 21mm lens would result in an AOV of 46.7 degrees

BMPCC 17.5mm, about 44.4 degree diagonal AOV - typically people will use a 16 or 17 or 18mm lens with an AOV of 48.2 or 45.7 or 43.4 degrees


For those who need to know, here are the approximate crop factors calculated for normalized 16:9 sensors (don't fret if they are not what you have heard as people usually round the values so they are easier to remember):

FF 135 film stills 1.0x

S35 film 1.45x

APS-C Canon 1.61x (I thinks APS-C Nikon is 1.53x but don't shoot me if I am wrong)

BMPC4K (and Academy 35mm film) 1.70x

MFT 2.08x based on physical sensor width (Panasonic GH2 is 1.86x in user selected 16:9 mode)

BMCC 2.28x

BMPCC 2.88x

Everyone says the crop for MFT is 2x but that number comes from the sensor diagonals or the image circles to cover the sensor and they are not comparing sensors that have been adjusted for a 16:9 aspect ratio. You get a different crop value since 135mm film is 36x24mm for a 3:2 aspect ratio and the MFT camera sensors are 4:3 if I recall correctly. When all sensors are considered as 16:9, simply divide 36mm by the width of the sensor in question to get the crop.

All values here have been calculated by the iPhone app Angle of View.

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Last edited by rick.lang on Fri May 24, 2013 4:49 pm, edited 2 times in total.
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MarcusWolschon

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Re: AW: BMC + Pocket as a set

PostFri May 24, 2013 4:36 pm

Actually the GH2 is a Mft camera but has 1.86 in 16:9 due to a multi aspect sensor.
The GH3 doesn't.
You're right that 35mm film is much smaller the 35mm full frame photo.
(film scrolling vertical, photo film horizontal through the camera)
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rick.lang

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Re: BMC + Pocket as a set

PostFri May 24, 2013 4:49 pm

MarcusWolschon wrote:Actually the GH2 is a Mft camera but has 1.86 in 16:9 due to a multi aspect sensor.
The GH3 doesn't.
You're right that 35mm film is much smaller the 35mm full frame photo.
(film scrolling vertical, photo film horizontal through the camera)


Thanks Marcus, I corrected my post.

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William Carswell

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Re: BMC + Pocket as a set

PostSat May 25, 2013 3:52 am

The last official "subject to change" I have is:

Production 4K: 1.65 crop
Pocket: 2.8 crop
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rick.lang

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Re: BMC + Pocket as a set

PostSat May 25, 2013 2:02 pm

LC wrote:The last official "subject to change" I have is:

Production 4K: 1.65 crop
Pocket: 2.8 crop


We have also heard BMD say the BMPCC is 3.02x crop. But they are all misleading values for use in a cinema camera in the sense they use the image circle to cover the diagonal of sensors with different aspect ratios as I explained in my earlier post. It is easier and more realistic to simply use the image width of all sensors when the images are then using the same 16:9 aspect ratio. Without that common aspect ratio, people are comparing diagonal angle of views on sensors with 3:2, 4:3, 16:9, and any other aspect ratio of whatever camera they may have. That only makes sense if they are shooting stills, but here we are assuming video to be projected at HD or other higher aspect ratios.

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Margus Voll

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Re: BMC + Pocket as a set

PostSat May 25, 2013 8:43 pm

Rick your point seems reasonable.

This is why i was referring to fov as it would be more universal measure instead
of calculating mm against ff.
Margus Voll, C.S.I.

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margus@iconstudios.eu
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rick.lang

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Re: BMC + Pocket as a set

PostSun May 26, 2013 3:50 am

Margus Voll wrote:Rick your point seems reasonable.

This is why i was referring to fov as it would be more universal measure instead
of calculating mm against ff.


Marty's, was that illustration using the 8mm lens on the BMPCC and showing the equivalent angle of views for the other cameras helpful? That was all I was trying to do but I got a little carried away with other illustrations!

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