Hello
I did some shots with my "new" Beaulieu 6008 S, and came out very sharp. I also did some ultra telephoto shots with the supplied lenses by the seller, and old screw mount Vivitar zoom (100-200) and an... unknown 500 mm, via a Cmount adapter. Both the shots were spectacular, unpredictably stable, but quite unsharp. I din't expect much of the 500 lems, but also the Vivitar shots were of not accptable quality, though carefully focused. I heard of the term "back focus adjustment". Could it be that the problem? What is exactly that, and how do you make the adjusment? Or, if it is a matter of lens quality, which lens, around 200 mm could do the job? A Nikkor 180 2.8? I also own a Canon EF 200 2.8, but I think there is no EF-c mount adapter, and there is no way, of stopping down the lens.
Any answers to all these questions?
Michael
WHAT IS THE BACK FOCUS ADJUSTMENT?
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DIEFTHINTIS
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Yemi
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DIEFTHINTIS
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Hi
The camera lens (6-90mm) is OK. The shots were taken with an aperture about f8. Because the SLR lenses are not so fast (3.5-4.0 for the 100-200. f8 for the 500mm) and of the focusing screen of the Beaulieu, which darkens at such aperures, it was difficult to focus (and very critical at such focal lengths), but I assume that I did my best. Also, did not seem to be in focus closer, or furter of my subject .
Michael
The camera lens (6-90mm) is OK. The shots were taken with an aperture about f8. Because the SLR lenses are not so fast (3.5-4.0 for the 100-200. f8 for the 500mm) and of the focusing screen of the Beaulieu, which darkens at such aperures, it was difficult to focus (and very critical at such focal lengths), but I assume that I did my best. Also, did not seem to be in focus closer, or furter of my subject .
Michael
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DIEFTHINTIS
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Steve P.
misc
Hi Michael,
1. Your English is great.
2. I don't have a certain answer to your question, just how I understand it in theory. I might well be wrong, and I hope someone will correct me if so.
With through-the-lens focusing, I think back-focus shouldn't matter with respect to operating through the viewfinder, but will for the focus distance marked on the lens. I think that is the phenomenon you describe: distance markings on the lens do not work for setting focus. That makes sense (at least to me!) because you've changed the dimensions with the c-mount adapter.
It is surprising to hear that the image did not appear more or less in-focus anywhere, but your depth of field may be very small! With a 500 lens, you might have a DOF of an inch! Unless there were some object right at that point, you might never know where the focus point was, and everything would look out of focus.
That probably isn't much help.
You might post to a photography forum like photo.net or USENET's alt.movies.cinematography.super8 or alt.movies.cinematography .
If you do find an answer, please post it back here!
1. Your English is great.
2. I don't have a certain answer to your question, just how I understand it in theory. I might well be wrong, and I hope someone will correct me if so.
With through-the-lens focusing, I think back-focus shouldn't matter with respect to operating through the viewfinder, but will for the focus distance marked on the lens. I think that is the phenomenon you describe: distance markings on the lens do not work for setting focus. That makes sense (at least to me!) because you've changed the dimensions with the c-mount adapter.
It is surprising to hear that the image did not appear more or less in-focus anywhere, but your depth of field may be very small! With a 500 lens, you might have a DOF of an inch! Unless there were some object right at that point, you might never know where the focus point was, and everything would look out of focus.
That probably isn't much help.
You might post to a photography forum like photo.net or USENET's alt.movies.cinematography.super8 or alt.movies.cinematography .
If you do find an answer, please post it back here!
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andy
Hi, may have something to do with lens quality as you suggested, i once used my 50mm f1.7 pentax lens on a R16, the results were no where as sharp as the 17-68 zoom on the camera.The optics of the pentax lens obviously dont have the resolving power, i reckon that 100-200mm lens wont be that great,whats the maximum aperature f4.5/5.6
thats makes for quite a dark viewfinder.Go for a prime lens say 200mm f4 nikon.Also with long and heavy lenses you really need to support them,otherwise you are putting a lot of strain on that c-mount..unless you require really long lens
shots i reckon the lens on your 6008 (6-70) is better suited, especially as its computed for the super 8 format.. back focus is i think referring to rear element of a lens, this must be at a set distance within the lenses c-mount, so when the lens is screwed into the camera the rear element of the lens is at the correct distance from the film plane, if this is out you get soft pictures on wide angle settings and when using the lens on infinity....i hope someone can explain this better and correct me if i am wrong.
thats makes for quite a dark viewfinder.Go for a prime lens say 200mm f4 nikon.Also with long and heavy lenses you really need to support them,otherwise you are putting a lot of strain on that c-mount..unless you require really long lens
shots i reckon the lens on your 6008 (6-70) is better suited, especially as its computed for the super 8 format.. back focus is i think referring to rear element of a lens, this must be at a set distance within the lenses c-mount, so when the lens is screwed into the camera the rear element of the lens is at the correct distance from the film plane, if this is out you get soft pictures on wide angle settings and when using the lens on infinity....i hope someone can explain this better and correct me if i am wrong.
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DIEFTHINTIS
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Hello
I am amazed that the normal Pentax 50mm lens was not good enough. The (forgotten...) 50mm is consindered to be the cheapest and best quality lens one can get in 35mm photography. Talking about the quality and the price of the lenses, have you ever seen the prices of the 35mm cine lenses? Can they be better than those for still photography? By the way, if you sit close enough to the screen (at a distance about the width of the screen) then suddenly, you see that the quality of the 35 film is not so great. You can even check, where different film stocks have been used, from the changing grain. I read somewhere, that the resolution of the projected 35mm film, is about 1000 lines, since it is a fourth ganeration dublicate, from the original negative.
Michael
I am amazed that the normal Pentax 50mm lens was not good enough. The (forgotten...) 50mm is consindered to be the cheapest and best quality lens one can get in 35mm photography. Talking about the quality and the price of the lenses, have you ever seen the prices of the 35mm cine lenses? Can they be better than those for still photography? By the way, if you sit close enough to the screen (at a distance about the width of the screen) then suddenly, you see that the quality of the 35 film is not so great. You can even check, where different film stocks have been used, from the changing grain. I read somewhere, that the resolution of the projected 35mm film, is about 1000 lines, since it is a fourth ganeration dublicate, from the original negative.
Michael
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Vatni
Hi!
Isn't back focus just about the fact that the lens is correctly callibrated/mounted/set so that when something is in focus, it is in focus no matter what focal lengh you use. the term back focus is used to describe the action of zooming in, focusing on your subject and then zooming out again. Your subject should still be in focus when you zoom out. if it's not, you need to set the back focus. Am I right or am I right. now, do you want to know how to do this?
Isn't back focus just about the fact that the lens is correctly callibrated/mounted/set so that when something is in focus, it is in focus no matter what focal lengh you use. the term back focus is used to describe the action of zooming in, focusing on your subject and then zooming out again. Your subject should still be in focus when you zoom out. if it's not, you need to set the back focus. Am I right or am I right. now, do you want to know how to do this?
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DIEFTHINTIS
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Carlos 8mm
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Back focus
I´m very interested to learn more about this too. 
I´ve problems when I zooming to focusing any object and when I zooming out the object looks out of focus ! ](*,)
Carlos.
I´ve problems when I zooming to focusing any object and when I zooming out the object looks out of focus ! ](*,)
Carlos.
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DIEFTHINTIS
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