On Mon, 24 Jan 2000 14:39:30 +0000, Malcolm Knight wrote:
>In article <388c5f53.0@news.per.paradox.net.au>, David Winter
> wrote:

>> Folks
>>
>> In looking at TV documentary material, probably shot on BetaCam or ProHi8
>> (3CCD, 1/2" or 2/3" triple CCD units):
>>
>> I notice how much greater depth of field these shots have than those I get
>> on domestic/prosumer gear. I have posted before about the losses going from
>> D8 back to VHS - as have others.
>>
>> A question for those who have used the consumer grade Hi8s and D8s, and the
>> triple chipper 1/2" and 2/3" CCD units:
>>
>> * am I right it's a combo of the "speed" of the lens (lower f, more light),
>> the quality of the glass and the sensitivity of the larger CCDs that gives
>> the broadcast (ENG) gear the greater depth of field as well as
>> "transparency"; but
>> * what is it that gives broadcast off-air stuff a better picture on VHS than
>> material shot on D8, edited on Raptor, and written straight to D8. Should I
>> get a *good* TBC or something to stick in between? Any suggestions.
>> * is the difference in depth of field between the D8s and
>> TRV900/PD100/DX{DA]100/GL1[XM-1] greater than between these and the big
>> chippers.

>Depth of field can be calculated from several factors.
>
>Things that improve depth of field are...
>
>Short focal lengths
>
>Small apertures (larger f numbers)
>
>Longer distance to subject
>
>Lower standards of what the viewer perceives as being sharp
>
>In theory a lens covering a large CCD must have a longer focal length in
>order to be able to do that and so all things being equal the broadcast
>camera will have poorer depth of field than a doemstic one with small CCDs.
>
>OTOH it will have far greater light gathering power which leads to a smaller
>aperture which gives a greater depth of field.
>
>I agree that pro units appear to give greater depth of field but unless it's
>all illusory it can only be due to more light and/or better low light
>performance. The optics themselves would tend to drag things the other way.
>
>A good wide-angle lens helps.

Sorry, nothing to add - I just wanted to compliment
you on the excellence of your response!