Static Idea

Steve Brady · May 27th, 2005, 12:23 PM

Dan, thanks for the reply. I don't think that using the DDS would cause distortion, though: Imagine any given point on the focusing screen as emitting a conical beam that arrives at the camcorder lens. The lens then focuses that beam back to a point on the CCD. It doesn't matter what the cross-section of the beam is, it always gets focused back to a point.

Still, if the guys at POC think that an angle as wide as 80˚ is the best one to use, then the DDS probably isn't suitable anyway.

Bill Porter · May 27th, 2005, 02:49 PM

Steve,

I wondered the same thing yet POC's site seems to explain in an example about a very similar application - almost identical depending on how you look at it - that the wider angle is more preferable:
http://www.poc.com/lsd/default.asp?p...tions&sub=hdst

Bill Porter · May 27th, 2005, 02:58 PM

Hey Dan,

Seeing as you are the only person who has tested both, what do you think about the Beattie vs the POC? I see in your gallery that at F4 and the same camera settings, the POC is much darker. Do you think the Beattie is better due to this? Or do you think a little bit of gain + a POC, is still better than a Beattie with no grain?

Perhaps a POC with a condenser is better than a Beattie hands down?

Dan Diaconu · May 27th, 2005, 06:23 PM

a picthshaaaa's worth a thousand words.(that is why I post them...) POC's grain is a bit smaller than Beattie, but still visible for a static. Soft focus is very nice as well. Light loss is 2-3 stops (this might make a difference for low light scenes between "can" and "can not" and otherwise general light levels needed) Is a very good option but unsuitable (IMHO) for PRO shoots (as a STATIC solution). Fantastic choice to "get your feet wet" (static) and pro results if moved (identical OPTICAL results with any other contraption including Mini and Pro35) obviously EXCEPT the image roation from the two prisms (robustness and other industry standard working levels, parts machined, aso)
I feel guilty enough to take away some of the "magic" of exploring....with my tests.
I will not be the one to kill the myth (IMO) of condenser lenses... it may be possible but I did not find "the way"... try it and find out...

Steve Brady · May 28th, 2005, 01:02 AM

I think that "myth" may be putting it a bit too strongly. Isn't the purpose of the condenser to gather all of the light that's missing the (in our case, camcorder) lens, and re-direct it towards the lens? And isn't that essentially the purpose of the fresnel on the Beattie? Seems to me, though, for the condenser to do the job it's intended to do, you'd need a fairly precise geometrical arrangement - just slinging an arbitrary lens in there and seeing what happens is unlikely to yield optimum results. Plus, Dan, you probably won't see much improvement by adding a condenser to the Beattie, because the fresnel on the Beattie is already doing the condenser's job. Or, again, am I talking rubbish?

Branching out a little, what happens when you move the 35mm lens further away from the screen, and zoom the camcorder out?

I'd imagine that:

The image on the screen becomes larger (this is useful, because the grain becomes relatively smaller, which we want).

The marked focus is thrown off - I think that the actual focal distance becomes closer than the marked distance, is that right? (How much "elbow room" do you get? would "useful" focusing distances all be crammed down at one end of the focus ring?)

The image becomes less bright (I'm really not sure whether this is right or not. I know that any given point on the screen will be dimmer according to the inverse square law, but the surface area of one pixel's worth of screen will be larger, so it ought to cancel out, oughtn't it?).

Dan Diaconu · May 28th, 2005, 06:53 AM

Quote:

Originally Posted by Steve Brady

Isn't the purpose of the condenser to gather all of the light that's missing the (in our case, camcorder) lens, and re-direct it towards the lens?

I can not say what I said I will not do. Try it and find out. Might be worth thinking about it before you touch one lens or condenser lens. Not playing games here, just leaving you some options open to explore (and possibly find out what I may be missing)
As for the rest.... nothing easier: try it!!! What YOU find out, no one can take away from you.

Daves Spi · June 1st, 2005, 07:41 AM

Quote:

Originally Posted by Steve Brady

Branching out a little, what happens when you move the 35mm lens further away from the screen, and zoom the camcorder out?

You will get bigger image, but impossible to focus infinity...

Dan Diaconu · June 1st, 2005, 08:48 AM

unless you move the lens mount to compensate..;-)<

May 27th, 2005, 12:23 PM	#31
Steve Brady Regular Crew Join Date: Feb 2005 Location: Rainham, Kent, UK Posts: 69	Dan, thanks for the reply. I don't think that using the DDS would cause distortion, though: Imagine any given point on the focusing screen as emitting a conical beam that arrives at the camcorder lens. The lens then focuses that beam back to a point on the CCD. It doesn't matter what the cross-section of the beam is, it always gets focused back to a point. Still, if the guys at POC think that an angle as wide as 80˚ is the best one to use, then the DDS probably isn't suitable anyway.

May 27th, 2005, 02:49 PM	#32
Bill Porter Major Player Join Date: Mar 2005 Location: Ventura, California, USA Posts: 751	Steve, I wondered the same thing yet POC's site seems to explain in an example about a very similar application - almost identical depending on how you look at it - that the wider angle is more preferable: http://www.poc.com/lsd/default.asp?p...tions&sub=hdst

May 27th, 2005, 02:58 PM	#33
Bill Porter Major Player Join Date: Mar 2005 Location: Ventura, California, USA Posts: 751	Hey Dan, Seeing as you are the only person who has tested both, what do you think about the Beattie vs the POC? I see in your gallery that at F4 and the same camera settings, the POC is much darker. Do you think the Beattie is better due to this? Or do you think a little bit of gain + a POC, is still better than a Beattie with no grain? Perhaps a POC with a condenser is better than a Beattie hands down?

May 27th, 2005, 06:23 PM	#34
Dan Diaconu Major Player Join Date: Dec 2004 Location: Vancouver, Canada Posts: 804	a picthshaaaa's worth a thousand words.(that is why I post them...) POC's grain is a bit smaller than Beattie, but still visible for a static. Soft focus is very nice as well. Light loss is 2-3 stops (this might make a difference for low light scenes between "can" and "can not" and otherwise general light levels needed) Is a very good option but unsuitable (IMHO) for PRO shoots (as a STATIC solution). Fantastic choice to "get your feet wet" (static) and pro results if moved (identical OPTICAL results with any other contraption including Mini and Pro35) obviously EXCEPT the image roation from the two prisms (robustness and other industry standard working levels, parts machined, aso) I feel guilty enough to take away some of the "magic" of exploring....with my tests. I will not be the one to kill the myth (IMO) of condenser lenses... it may be possible but I did not find "the way"... try it and find out...

May 28th, 2005, 01:02 AM	#35
Steve Brady Regular Crew Join Date: Feb 2005 Location: Rainham, Kent, UK Posts: 69	I think that "myth" may be putting it a bit too strongly. Isn't the purpose of the condenser to gather all of the light that's missing the (in our case, camcorder) lens, and re-direct it towards the lens? And isn't that essentially the purpose of the fresnel on the Beattie? Seems to me, though, for the condenser to do the job it's intended to do, you'd need a fairly precise geometrical arrangement - just slinging an arbitrary lens in there and seeing what happens is unlikely to yield optimum results. Plus, Dan, you probably won't see much improvement by adding a condenser to the Beattie, because the fresnel on the Beattie is already doing the condenser's job. Or, again, am I talking rubbish? Branching out a little, what happens when you move the 35mm lens further away from the screen, and zoom the camcorder out? I'd imagine that: The image on the screen becomes larger (this is useful, because the grain becomes relatively smaller, which we want). The marked focus is thrown off - I think that the actual focal distance becomes closer than the marked distance, is that right? (How much "elbow room" do you get? would "useful" focusing distances all be crammed down at one end of the focus ring?) The image becomes less bright (I'm really not sure whether this is right or not. I know that any given point on the screen will be dimmer according to the inverse square law, but the surface area of one pixel's worth of screen will be larger, so it ought to cancel out, oughtn't it?).

June 1st, 2005, 08:48 AM	#38
Dan Diaconu Major Player Join Date: Dec 2004 Location: Vancouver, Canada Posts: 804	unless you move the lens mount to compensate..;-)<