Andrew Clunie
April 23rd, 2007, 04:28 PM
Hey guys. I am fairly new to this stuff, so my knowledge is pretty limited, but i have learn't pretty much all i know from this site so thank you all!
Right, i have started putting together my adapter and i am wondering how you have yours set up. What i have come to understand, this seems the ideal one for me:
Lens.....GG...condenser....macro...camera
I was just interested to see how you guys have yours set up cause i have come across so many different ways. Also i have a question. Does a Macro do the same thing as an achromatic lens? And is a pcx lens similar to a condenser lens? Do they both reduce vignetting or am i way off?
Thanks, Andrew
Mike Dulay
April 23rd, 2007, 06:40 PM
Andrew,
I'm currently using a static, working on a vibrating and a spinner. My static setup is:
Nikon Lens - F-mount - Nikon F3 Type D (Condenser and GG) - 58mm +10 Singlet Macro - camera
see the story at http://yousillyman.blogspot.com
When people say macro they often mean the singlet macro (diopeter) which does the same thing BUT does not correct for chromatic aberration. It's primary function is to allow your camera to focus on the focus screen. An achromatic diopeter has two lenses instead of one. This corrects the chromatic aberration and is visually better. An apochromatic diopeter has three lenses ....
PCX = plano convex lens, which refers to the condenser's shape. This is flat on one side and a shallow rounded curve on the other. The condenser is there to reduce vignetting as you mention.
Most beginners start with either a static or a spinner. Which one you go with depends on how easily you can get a ground glass.
Bob Hart
April 23rd, 2007, 09:36 PM
Vignetting versus edge/corner brightness fall-off, also sometimes known as hotspot.
Vignetting is the edges of the optic itself cutting off the corners off the image by being too small in diameter. The cut off areas are dark, the effect something like looking down a pipe if the vignetting is extreme.
Edge/corner brightness fall-off is the gradual darkening towards the corners or edges but image is otherwise there across the whole frame. The darker areas are caused by inability of the optics to deliver even light value across the whole frame.
To complicate things, a vignette and edge/corner brightness fall-off might be caused by the optic being too small in diameter.
The edge/corner brightness fall-off will be seen first, then the vignette itself appears if the guilty optical element is moved forward.
A condenser or PCX lens or pair can help with edge/corner bightness fall-off.
These are my understandings of the definitions. Maybe somebody should correct me if I am wrong.
Chris Barcellos
April 23rd, 2007, 10:04 PM
Hey Andrew:
I built a spinner, using plans from Redrockmicro people and there disk as my guide. I used a 72mm achromat from Cinevate at about $250.00. I had no condensor, but I did have about a 5 inch spacer from the achromat to the ground glass. This gave me good focus on good image and room to zoom in and out. I am able to focus my FX1 to fill the screen with a Pentax normal lens.
Here is what the contraption looked like. It actually turned out pretty solid.
http://www.dvinfo.net/conf/attachment.php?attachmentid=1327&d=1164515894
See this thread for more discussion.
http://www.dvinfo.net/conf/showthread.php?t=80383
I now have a Letus35a, and it uses an achromat as well as a condenser. It does not give a huge zoom range, but he image appears to be better.
Andrew Clunie
April 24th, 2007, 04:34 AM
Thanks for the informative replies.
I made a real quick crude model, just to pretty much see the projection on gg. My gg is very poor at the mo (a shoddy sanded cd) so there is major hotspot and vignetting. I have another cd which i will sand with finer sand paper and put a lot more time into it, so i was wondering, to get rid off the vignetting and hot spot, i need a condenser, but should i put it between the gg and lens, or gg and camera.
lens...condenser...gg...macro..cam or
lens...gg...condenser...macro...cam
also, does it matter how far or close the condenser is to the gg?
Tell me the way you have yours set up, ie in what order things are.
edit: Also is the redrock guide worth getting? It seems useful, especially for the gg thats included. Is the GG in the form of the cd? sorry for all the questions :)
Thanks, Andrew