Matt Choules
05-24-2009, 04:37 PM
Hi Everyone,
I lurk on this forum from time to time asking questions, but mainly post on the HV20 forum as this is the cam I use.
I bought a TwoneilHD Static adapter for use with my HV20, and was lucky enough to get a HV20ACHR1 achromat, which some of you will know is Zeiss optics salvaged from 1970's electon microscopes. Apparently.
Now, I am getting pretty decent results in sunny conditions, and the bokeh in the shallow DOF is glorious.
http://vimeo.com/4326099
The CA is minimal but vignetting is still an issue due to the use of wider apertures. I am also limited in low light and if I want to stop my lenses down to have a wider DOF. The Nikon Nikkor 50mm f1.4 AI lens I use has no flaring at around f4 so I would like the option to shoot at that aperture on occasions that suite the need, or possibly even lower if I wanted a very wide DOF.
I have found my Nikon 50mm can only stop down around 4 stops from f1.4 before I start to notice the grain of the focussing screen, which is a Canon EE-A focusing screen, and whats worse, rings from the screen become very visible.
I thought about replacing the Canon EE-A screen with a finer ground glass screen of around 5 microns, however, I understand that a condenser is required to remove hotspots. This is apparently also true of the commonly used EE-A and EE-S screens which have their own fresnel condenser build in.
Ok, so that explains the fresnel rings in my image with the Canon EE-A.
So looking at Daniels guides he shows using a Bi-Aspheric, Plano Convex or cheaper Bi-Convex lens AND an achromat. The order going:
35mm Lens | GG | Condenser | Achromat | Video Camera
Some other people say that a condenser would be best in front of the GG.
It was at this point I also thought about going for a vibrating GG holder, as this would definately remove the grain. However I am aware that if a pancake motor is used often the resulting video is wobbley. Another alternative to this is to use a rotary or cylindrical motor. But this requires a "suspended" holder so that it can move slightly in a (almost) circular motion.
With a moving GG holder it would be almost impossible to get the condenser right in front of the GG, so that pretty much removes that option.
We're getting closer to my questions now, don't give up.
Do you think its best to have the condenser in between the achromat and GG or in front of the GG behind the 35mm lens?
Has anyone built an adapter with both an achromat and condenser, and a vibrating GG?
Does anyone in the UK (West Midlands preferably), with great lens knowledge, have any spare time so that I can talk this through with them in person?
Can anyone suggest a good source of lenses (pref. Bi-Aspheric)?
I lurk on this forum from time to time asking questions, but mainly post on the HV20 forum as this is the cam I use.
I bought a TwoneilHD Static adapter for use with my HV20, and was lucky enough to get a HV20ACHR1 achromat, which some of you will know is Zeiss optics salvaged from 1970's electon microscopes. Apparently.
Now, I am getting pretty decent results in sunny conditions, and the bokeh in the shallow DOF is glorious.
http://vimeo.com/4326099
The CA is minimal but vignetting is still an issue due to the use of wider apertures. I am also limited in low light and if I want to stop my lenses down to have a wider DOF. The Nikon Nikkor 50mm f1.4 AI lens I use has no flaring at around f4 so I would like the option to shoot at that aperture on occasions that suite the need, or possibly even lower if I wanted a very wide DOF.
I have found my Nikon 50mm can only stop down around 4 stops from f1.4 before I start to notice the grain of the focussing screen, which is a Canon EE-A focusing screen, and whats worse, rings from the screen become very visible.
I thought about replacing the Canon EE-A screen with a finer ground glass screen of around 5 microns, however, I understand that a condenser is required to remove hotspots. This is apparently also true of the commonly used EE-A and EE-S screens which have their own fresnel condenser build in.
Ok, so that explains the fresnel rings in my image with the Canon EE-A.
So looking at Daniels guides he shows using a Bi-Aspheric, Plano Convex or cheaper Bi-Convex lens AND an achromat. The order going:
35mm Lens | GG | Condenser | Achromat | Video Camera
Some other people say that a condenser would be best in front of the GG.
It was at this point I also thought about going for a vibrating GG holder, as this would definately remove the grain. However I am aware that if a pancake motor is used often the resulting video is wobbley. Another alternative to this is to use a rotary or cylindrical motor. But this requires a "suspended" holder so that it can move slightly in a (almost) circular motion.
With a moving GG holder it would be almost impossible to get the condenser right in front of the GG, so that pretty much removes that option.
We're getting closer to my questions now, don't give up.
Do you think its best to have the condenser in between the achromat and GG or in front of the GG behind the 35mm lens?
Has anyone built an adapter with both an achromat and condenser, and a vibrating GG?
Does anyone in the UK (West Midlands preferably), with great lens knowledge, have any spare time so that I can talk this through with them in person?
Can anyone suggest a good source of lenses (pref. Bi-Aspheric)?