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how wide needs to be?


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#1 Interceptor121

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Posted 28 December 2012 - 02:25 PM

I come from a background in stills where fisheye is what you look for, however it seems that in video barrel distortion is a no go
So having had a look around it would seem that in video:
Dome ports give 65 degrees
Wide angle is between 80-90
Super wide is around 110
Nobody shoots more than 110 FOV because of distortion

Is this correct?

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#2 r4e

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Posted 29 December 2012 - 12:43 AM

Before investing into something more costly, there is a simple way to experiment which FOV you prefer underwater. Purchase or loan a GoPro 2 (or 3). It has a couple of options concerning field of view. Although the video quality is not terribly good, I have one connected on top of my video housing and I normally set it to record constantly during the dive. Sometimes this helps in getting a missed shot especially in situations where the FOV of the main camera was not wide enough.

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#3 Interceptor121

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Posted 29 December 2012 - 04:12 PM

Am sorry maybe I have not made myself clear
An talking about in terms of professional or semiprofessional production what are the standards
Gopro is a device that is unique and also I would not define semipro so not a term of reference
I would like to hear from users of dedicated video equipment

#4 Drew

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Posted 29 December 2012 - 06:39 PM

The standards can't be stated in the terms you use, in terms of °. Professional lenses go by S35mm standards in lens focal length, not arbitrary angle of view. This is because marketing hyperbole (110° is really 110° diagonally and rounded etc) which doesn't use the standards.
All you need to see a standard is to look at cinelenses like the Arri Aluras or Canon's CineEOS lenses, which cater to the S35mm standard. In general, about 15mm is the widest so that distortion and other lens abnormalities can be controlled. Esthetically, I like the angle of view from 14.5-16mm to shoot most things, but the conditions (visibility) have to be pretty good to shoot in for big mammals like whales.
Howard Hall uses fisheye in IMAX productions. Ultimately, it's an esthetic choice whether to use a fisheye since the distortion can be somewhat controlled and even fixed in post nowadays.
FYI a dome port merely negates the effects of water refraction, and angle of view depends on the lens used.

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#5 Interceptor121

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Posted 30 December 2012 - 12:14 AM

Drew thanks for the useful response
Yes I am aware domes restore air field of view and the 65 degrees were round about the 35mm you mentioned
I have been testing videos with compact (still) set ups for a while now and I am trying to make some comparisons
A modern compact camera has a 24mm equivalent lens which is 84 degrees diagonal
I would think that with a dome this is perfectly adequate to most situations and you can use the camera zoom
If the camera has also very short minimum focussing distance I believe that for most situations the camera with a dome works without any additional equipment
I have tried 28mm equivalent cameras but i need to use wet lenses that can't zoom so I am continuously taking lenses on and off in water i look forward to skipping that

#6 Drew

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Posted 30 December 2012 - 10:07 AM

You are comparing 35mm still film focal lengths. S35mm in cinematic film is different (approx 1.6x crop of 35mm full frame sensors). Only a few compact still cameras have APS 1.6x crop or 35mm sensors. Most have smaller like 1/2" sensors etc., so focusing distance is less of an issue.

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#7 Interceptor121

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Posted 30 December 2012 - 10:55 AM

It is an issue with the RX100 I have been using for the last few months in fact I need a diopter even for basic macro
Anyway I got the essence of it thanks very much

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