Ground Glass DIY questions
Moderator: Andreas Wideroe
Ground Glass DIY questions
I posted this over at Brantley's site, but I haven't gotten much of a response yet. Maybe some of you guys know. I have a bauer c2 super, and I believe that it came with a ground glass rangefinder, but there isn't one in the camera. Well, whether it was there or not, I want to try to add in my own ground glass. The most important aspect that I know of is to have the ground glass the exact distance from the beam splitter as the film. Is it possible to make this adjustment optically. I was thinking about setting the lens to infinity and then adjusting the ground glass until objects at an infinite distance are clear. It makes sense to me, but then again, I don't exactly know what I'm doing. I actually tried it out with a sanded-down piece of clear plastic for trial purposes, and I was impressed! I do think it would work if I could make/find an appropriate glass, and get it to the right position. This camera has many nice features, and it only has crosshairs in the viewfinder. why put in all of these nice features without a rangefinder? The technology was certainly there (late 60's). It has also been through some abuse as well, so it wouldn't surprise me. I only paid 15$ for it, so I am open to experiminting with it. I have alread opened it up, and had a look around, and I managed to put it back together correctly, so I feel pretty confident. Pedro, maybe you know whether I can adjust the distance going by optics alone. You seem to know a lot about ground glass.
-
Guest
I think the ground glass you could buy as a Beaulieu spare part or take it out of a "dead" Beaulieu (not 6008 standard versions!).
The adjustmente is VERY problematic, becaue you act in micrometer ranges! You would have to mout the ground glass in a frame, that can be adjusted in the camera with micrometer spindles.
Even the ground glass shows a part of the air image, so that the eyepiece setting of the viewfinder still has some effect.
To start with adjustment, I would focus infinity in wide angle range and look thru the viewfinder, setting it to the grain of the ground glass. Now the ground glass position must be adjusted to clearest viewfinder result, adjusting the viewfinder itself always behind, until finally finding a position, where the infinity image is best possible.
Then I would zoom onto far away details (antennas) and check, if that details come out of focus when changing the focus setting slightly.
When all positive, then I would do some focusing tests in the near/mid range, cross-checking the result with a meter tape or/and a SRL 35 mm AF camera with long zoom lens.
A correct adjusted ground glass shows any focus changes very accurate and is tolerant to changes in viewfinder settings. But, as I remarked, a wrong viewfinder setting can make the user´s eye accomodate to the rest of the airial image and cause wrong focussing results.
But honestly, I doubt that it makes much sense for such a camera. A prism viewfinder takes about the half of the initial amount of light, so that an aditional ground glass would make the image very dark, perhaps making the ground glass useless. Beaulieu cameras use a mirror shutter, reflecting 100% of the light to the ground glass.
Another problem is the exposure meter. Depending on it´s position, it may be affected by any modifications.
Pedro
The adjustmente is VERY problematic, becaue you act in micrometer ranges! You would have to mout the ground glass in a frame, that can be adjusted in the camera with micrometer spindles.
Even the ground glass shows a part of the air image, so that the eyepiece setting of the viewfinder still has some effect.
To start with adjustment, I would focus infinity in wide angle range and look thru the viewfinder, setting it to the grain of the ground glass. Now the ground glass position must be adjusted to clearest viewfinder result, adjusting the viewfinder itself always behind, until finally finding a position, where the infinity image is best possible.
Then I would zoom onto far away details (antennas) and check, if that details come out of focus when changing the focus setting slightly.
When all positive, then I would do some focusing tests in the near/mid range, cross-checking the result with a meter tape or/and a SRL 35 mm AF camera with long zoom lens.
A correct adjusted ground glass shows any focus changes very accurate and is tolerant to changes in viewfinder settings. But, as I remarked, a wrong viewfinder setting can make the user´s eye accomodate to the rest of the airial image and cause wrong focussing results.
But honestly, I doubt that it makes much sense for such a camera. A prism viewfinder takes about the half of the initial amount of light, so that an aditional ground glass would make the image very dark, perhaps making the ground glass useless. Beaulieu cameras use a mirror shutter, reflecting 100% of the light to the ground glass.
Another problem is the exposure meter. Depending on it´s position, it may be affected by any modifications.
Pedro
-
Guest
Thanks for the help, pedro
Hey, thanks for the help. I know it is possible that it wouldn't work, but why not try it? I am pretty sure I can make it as non-invasive as possible, and I would like to try it anyway, since I'm a little disenchanted with the fact that it doesn't have any type of range finder. But I've read that Bauer C2 supers have ground glass from various sources. I suppose I'll have that completely cleared up when the manual comes in. But you gave me exactly what I needed as far as help is concerned. I'll have to get some way to adjust the glass. I am in the mood to tinker with something, so I guess my new camera will be my next victim! But maybe it will work? Thanks again
-
mIke
Man I doubt this information about ground glass at your camera...
Pedro, you wrote regarding the viewfinder-focussing at Super8s:
>most have split image, because the beam divider technology does not provide the sufficient amount of light for using ground glass.<
Formerly expensive high end S8 cameras have split image and some good quality compact cams, that were higher priced at the time they were sold, too. Lots of cams, mainly the simpler ones have not split image... Cameras also differ in the brightness and size of the viewfinder image affecting the ease of measurement. Darkness is a general problem ...;)
>But you must try the difference, f.e. focussing with a relatively cheap Beaulieu 4008 and compare it to the split image!<
I would like...
So far I know ground glass screening from my SLR still cam having 3 different viewfinder focussing systems combined. With a Leicina special you can also at least choose 1 out of 3 systems.
>Split image CAN or COULD be precise, if you always had regular lines of high contrast in your picture and you have enough time to focus.<
IS nt it the then MOST precise way of distance metering?
>The point is, that shooting film often don´t give you much time for camera settings, and with ground glass you can focus any structure at any place on the screen.<
I agree. Well in this case how about a fixfocus setting (allowing sufficient DoF by moderate focal lengths) or an orientation to lens distance indications? But both methods probably lack the precision that you might desire?
>Airial image focussing with split indicator shows the same behaviour when focussing the lens or focussing the eyepiece. So the slightes off-position of the eyepiece damages all focussing results.<
In case that problem should really occur, how about simply marking and fixing the correct eyepiece position? You may need to use the viewfinder diopter setting (?) also with ground glass.
>Only the ground glass prevents your eye to accomodate wrong viewfinder settings and will certainly increase your output of sharp footage significantly.<
OK but is the ground glas screen focussing not also prone to the individual (subjektive) eyesight (Fehlsichtigkeit)?
>THe other point is, that the centered measuring field indirectly influences the picture composition. There is always the risc to focus the centre and then shoot, without moving the camera back to the "photographic" correct position.
That´s why most fotos show the persons without legs and with a lot of wall behind!<
Whose what? I offer my condolescences... ;)
Do you mean zooming out after applying maximum focal length for distance metering-which can also be recommended for precise automatic aperture measurement ?
Common, the viewfinder system is usually parallaxe-free and you can see what you film when you press the trigger.
Finally to avoid a misunderstanding, no doubt that Beaulieus are great, nice cameras and ground glass focussing is very powerful. But was not the latter, due to economy and its technical limitation, succesfully replaced/outcompeted by split image at Super8 high end models ?
Servus, Mike
Pedro, you wrote regarding the viewfinder-focussing at Super8s:
>most have split image, because the beam divider technology does not provide the sufficient amount of light for using ground glass.<
Formerly expensive high end S8 cameras have split image and some good quality compact cams, that were higher priced at the time they were sold, too. Lots of cams, mainly the simpler ones have not split image... Cameras also differ in the brightness and size of the viewfinder image affecting the ease of measurement. Darkness is a general problem ...;)
>But you must try the difference, f.e. focussing with a relatively cheap Beaulieu 4008 and compare it to the split image!<
I would like...
So far I know ground glass screening from my SLR still cam having 3 different viewfinder focussing systems combined. With a Leicina special you can also at least choose 1 out of 3 systems.
>Split image CAN or COULD be precise, if you always had regular lines of high contrast in your picture and you have enough time to focus.<
IS nt it the then MOST precise way of distance metering?
>The point is, that shooting film often don´t give you much time for camera settings, and with ground glass you can focus any structure at any place on the screen.<
I agree. Well in this case how about a fixfocus setting (allowing sufficient DoF by moderate focal lengths) or an orientation to lens distance indications? But both methods probably lack the precision that you might desire?
>Airial image focussing with split indicator shows the same behaviour when focussing the lens or focussing the eyepiece. So the slightes off-position of the eyepiece damages all focussing results.<
In case that problem should really occur, how about simply marking and fixing the correct eyepiece position? You may need to use the viewfinder diopter setting (?) also with ground glass.
>Only the ground glass prevents your eye to accomodate wrong viewfinder settings and will certainly increase your output of sharp footage significantly.<
OK but is the ground glas screen focussing not also prone to the individual (subjektive) eyesight (Fehlsichtigkeit)?
>THe other point is, that the centered measuring field indirectly influences the picture composition. There is always the risc to focus the centre and then shoot, without moving the camera back to the "photographic" correct position.
That´s why most fotos show the persons without legs and with a lot of wall behind!<
Whose what? I offer my condolescences... ;)
Do you mean zooming out after applying maximum focal length for distance metering-which can also be recommended for precise automatic aperture measurement ?
Common, the viewfinder system is usually parallaxe-free and you can see what you film when you press the trigger.
Finally to avoid a misunderstanding, no doubt that Beaulieus are great, nice cameras and ground glass focussing is very powerful. But was not the latter, due to economy and its technical limitation, succesfully replaced/outcompeted by split image at Super8 high end models ?
Servus, Mike
Hi Mike,
First, I worked for years with any kind of focussing system, also several cameras with split image and I was rather dissappointeds. My last one of that kind, the Agfa MOS10, had a big split image, too. And everytime, when I had been successful to match the vertical lines , one half of the split image appeard sharp and the other out of focus. So, for exact focussing, I had to alighn a sharp vertical structure with a unsharp vertical structure. And if successful, AND my subect was even in place after focussing, I could shoot and hope. I had the camera adjusted, but they told me, that it is not better possible. Other brands I had tried, too, with split imate, with flicker spot, with hair cross, anything.
The viewfinder setting influences DIRECTLY the result. It it is not accurate and s/("§ like at the Canon 514, you run the risk to trash the half of our mid-distance and close-up shot.
Leicina I never had, but it may be great, too. My first positive results, comparable with SRL cameras, I had with Beaulieu, inspite of the high costs. The ground glass is bright and clear because of the special shutter construction of the Beaulieus, no beam splitter. Eye accomodation is nearly not possible, when the eye piece is out of adjustment, the image simply cannot be focused totally. And the eye piece is very precise at Beaulieus.
And they are the only cameras that are alive still today, with this technology!
Pedro
First, I worked for years with any kind of focussing system, also several cameras with split image and I was rather dissappointeds. My last one of that kind, the Agfa MOS10, had a big split image, too. And everytime, when I had been successful to match the vertical lines , one half of the split image appeard sharp and the other out of focus. So, for exact focussing, I had to alighn a sharp vertical structure with a unsharp vertical structure. And if successful, AND my subect was even in place after focussing, I could shoot and hope. I had the camera adjusted, but they told me, that it is not better possible. Other brands I had tried, too, with split imate, with flicker spot, with hair cross, anything.
The viewfinder setting influences DIRECTLY the result. It it is not accurate and s/("§ like at the Canon 514, you run the risk to trash the half of our mid-distance and close-up shot.
Leicina I never had, but it may be great, too. My first positive results, comparable with SRL cameras, I had with Beaulieu, inspite of the high costs. The ground glass is bright and clear because of the special shutter construction of the Beaulieus, no beam splitter. Eye accomodation is nearly not possible, when the eye piece is out of adjustment, the image simply cannot be focused totally. And the eye piece is very precise at Beaulieus.
And they are the only cameras that are alive still today, with this technology!
Pedro
-
mIke
Hi, Pedro
'picked up the discussion again.
If you worked long with several split image cams you may had noticed obvious differences in their capability for achieving precision. Here it needs to be mentioned that, as for other technical features e.g. the beamsplitter, for those distance-metering/viewfinder-systems there were notable quality differences between the models/manufacturer.
Regarding its distance metering precision I would like to have compared the model you mentioned with late top of the line machines forinstants high ends from Canon, Nikon or a Nizo S.
Because (I assume) the particular problem you described for the Movexoom should hardly be observed on them.
As you said indirectly in your final sentence: The Leicina special does not have ground glass so why it should give better results to you in this respect?
Best. Mike
'picked up the discussion again.
If you worked long with several split image cams you may had noticed obvious differences in their capability for achieving precision. Here it needs to be mentioned that, as for other technical features e.g. the beamsplitter, for those distance-metering/viewfinder-systems there were notable quality differences between the models/manufacturer.
Regarding its distance metering precision I would like to have compared the model you mentioned with late top of the line machines forinstants high ends from Canon, Nikon or a Nizo S.
Because (I assume) the particular problem you described for the Movexoom should hardly be observed on them.
As you said indirectly in your final sentence: The Leicina special does not have ground glass so why it should give better results to you in this respect?
Best. Mike
-
mIke
My focussing-method knowledge in short:
Common for most cam‘s:
Lens distance indications (m/f): estimation/ exact measurement possible as well as controll over DoF when employing a DoF chart
Differing in the viewfinder (example):
1)Aerial image/ cross hair: good general visual orientation (Bauer C8),
2)Mixed or double image: for lower range zoom lenses (Nizo 148m)
3)Microprisms: good for e.g. portrayal work (Canon 814e),
4)Split image: highly precise at a straight lined or a structured object (Nizo S56),
5)Ground glas screen: visual DoF control, bright instant focussing/copy work (Beaulieu 4008 ZM)
6)Dichroid something: what is this, related to 2)? (older Beaulieu, 2008?)
Common for most cam‘s:
Lens distance indications (m/f): estimation/ exact measurement possible as well as controll over DoF when employing a DoF chart
Differing in the viewfinder (example):
1)Aerial image/ cross hair: good general visual orientation (Bauer C8),
2)Mixed or double image: for lower range zoom lenses (Nizo 148m)
3)Microprisms: good for e.g. portrayal work (Canon 814e),
4)Split image: highly precise at a straight lined or a structured object (Nizo S56),
5)Ground glas screen: visual DoF control, bright instant focussing/copy work (Beaulieu 4008 ZM)
6)Dichroid something: what is this, related to 2)? (older Beaulieu, 2008?)