B&H 70-DR, 70-DL or 70-DA?... or Go With The K-3?

[coors]

Fantastic reading, Eric!!! You certainly seem to have a good handle on "understanding your subject" here. I will have to read and reread many, many times...
Could you clear up one simple thing for me? Are the terms lens collimation and lens registration one in the same? I've always had a picture in my mind that collimation had something to do with centering the final circle of light from a lens... either into an eyepiece (telescope) or onto the films frame. And I've always thought that lens registration was bringing the lens into focus properly at the film.
Thanks for writing these exhaustive pieces of information, here. If you ever write a book on this subject, complete with photos and diagrams, I'd certainly be willing to buy it!

Owen

[ericMartinJarvies]

Fantastic reading, Eric!!! You certainly seem to have a good handle on "understanding your subject" here. I will have to read and reread many, many times...
Could you clear up one simple thing for me? Are the terms lens collimation and lens registration one in the same? I've always had a picture in my mind that collimation had something to do with centering the final circle of light from a lens... either into an eyepiece (telescope) or onto the films frame. And I've always thought that lens registration was bringing the lens into focus properly at the film.
Thanks for writing these exhaustive pieces of information, here. If you ever write a book on this subject, complete with photos and diagrams, I'd certainly be willing to buy it!

Owen

i do not know for certain the industry and technical terms for each. but what i have adopted for myself is that collimation or colimating is something that takes place from and between the front glass/optic and the rear glass/optic. whereas adjustment or as you stated 'registration' would be the relationship between the mount of the lens and the mount of the camera.

most lenses do not need to be collimated. when needed, it is usually a result of dropping the lens and thus having the optics move off axis or off linear point in space, or because it has been worn out inside where the glass meets the housing, or things along these lines.

and even if you did have a lens that was in need of a collimation, it would most likely be usable and undetected, unless the optics where moved forward or back on their linear mark. as it relates to their x,y,z mark/position of the glass elements/optics, the housings usually have such tight tolerances, that this particular type of optical alignment is not required on most pieces of glass. but this depending on their actual magnification powers, diameter in relationship to the opposing element, and the thickness as well, or any and all or some i have not mentioned. light travels in straight lines, so if an element did get wacked out of axis, and it was bad, you would visually see it. so rule of thumb ... if you can not visually see a problem your lens does not need to be collimated ... except if this visual problem has to do with focussing. but this stuff is not even worth addressing as it is a rare occurence ... ask how many people have had to have their lenses collimated, and aks them what was the symptom and reason for the collimation to occur in the first place. it is more likely then not that they merely had their lens adjusted or registered as you stated, wherein the tech found the happy spot for the lens mount and the camera mount, and their connective relationship thereof.

the easiest way to understnad this is to go into a dark room and use a little led flashlight and a lens and point the light through the lens and see how it opens up on the wall. see the differance in size between a 10mm, a 25mm, a 50mm, a 75mm, and a 100mm lens. then move the lenses closer and further from the light. then place film between the lens and the light and move each one closer or further from one another ... and do this in both the taking side of the lens and on the backside/projecting side of the lens. if you have a slide, take and place it on the large side of the lens(taking side, non mount side) and then point your light at it, and see how it comes out the back side of the lens ... again, moving each element along a linear line closer or futher from one another ... and you will find immediatly where that lens comes into focus on the back side. well, is this not the same thing that happens when it is on your camera when t is going ot reach the surface of your film to thus expose it? yes, it is. so if you just play around with a lens and a flashlight and some type of film transparanty, then you will get a good feel for how the differant types of lenses take and manipulate the light path as it passes through the lens. if you have some junk lenses, take them apart and pair up some elements and see what shape and sizes and aspect and skews you can get with them.

eventually it will all start making some sense.

you could actually take a lens made for 8mm film, and by taking it apart and repositing the elements, you could make a foccusable image the size of 35mm. and the same with a 35mm lens down to an 8mm size image(perhaps not with all elements, but you get the point). its all negotiable, and the trade off is quality and color. so what realy becomes the challange in making a good lenses is not obtaining a certain focussable sized image, but one that is rich in color and resolution.

i recently purchased some kodak lenses ... a set of 3 and one has a wide angle attachment. the ebay ad said he was able to cut images taken with these lenses in with his zeiss lenses. fairly bold statement considring zeiss makes some pretty good glass. but sure enough, the lenses did yild high quality images, but not without having to make compensations with the incoming light. so it is all relative in terms of making comparisons ... with lenses it is not as easy as comparing apples with apples and oranges with oranges. and in the end, if what you are imaging is going to television, most any decent lens will do the job. it is when an image must be blown up to movie theatre screen size that the quality of the glass really comes into play. but again, we have outside variables that will dictate this ... be it the exposure itself or the processing itself or so on.

eric

[bakanosaru]

thanks for your "rant" Coors.
thanks for your sense of humour and/or honesty.
sometimes reading this forum I forget why I shoot super 8.

baka

[jaxshooter]

Actually, the Beaulieu camera can't be converted because of the optics. I don't know the exact technical reasons and I know some cameras that have been converted, but according to Björn Andersson who repairs and builds these cameras there are some big problems concerning this conversion.>
< OK,my bad.Maybe I'm confusing the R-16 with a later Beaulieu (the 2016 I think?Seems like Chambliss out of Atlanta used to sell those).I think that's a factory made 16-S-16 switchable.I think if you look around,one of those could be had reasonably priced.
By cheap super 16,it all depends on what you consider cheap.The Ikonoskop has no appeal to me at all personally.Non reflex is a big turn off to me,although I have shot some really great stuff with a Bell and Howell filmo.By the same token,I've gotten hosed by not being able to see what the lens is seeing.
I would try to find a converted Eclair ACL or NPR or perhaps if the money could be squeezed out an Aaton LTR.I've seen them as low as 2500 USD.

[jean]

live and learn ... thus is life. i hope this information was of some use.

Eric, thank you very much for writing and sharing all this!! I've been shopping now for some tools, and am surprised how little they cost. I was unaware of the problem that the threads are not always the same, and some lenses thread in deeper than others. In fact it is obvious, I just mounted a lens in different cameras, and it ended up in different positions at each camera. I never noticed this before, but it is pretty obvious. Perhaps the idealistic goal to put all lenses on all my c-mounts is not realistic, but I will see this when the tools arrive.

You mentioned an c-mount digital camera, I am currently abusing a web cam for this purpose, I am putting it into a new case and bought a nice, steel (alu is very soft, and wears out easy) c-mount for it. My goal is to adjust it ecactly to c-mount spec, and afterwards it should be much easier to adjust the lenses with this camera, since there is a live image on the screen to judge the results. And it will be useful for telecine experiments, but this is another project

In theory, should I manage to adjust both the webcam and the film camera to c-mount spec, the lens should be at least very close to the optimal adjustment.

Another idea of mine is to use a digital chip instead of film in the camera, the problem here is that there seems to be to little space, or I would have to take out the filmgate and substitute it with something the same thickness, so that the chip is in the same position than the film would be, but this would add another variable. Should this work, there would be a live image on screen and the performance of the lens/camera combo could be judged very conveniently without the extra hassle of test films! At least for s8, I have yet to find a digital camera that is small enough to be brought into position. A nice final product would be a digital chip in an s8 cart, so every s8 camera could be tested fast and conveniently.

And why go through all this? One reason is because I want to be independent, the more I know and am able to do, the more I can achive with my limited budget and equipment. It allows me to tap the pool of c-mount lenses at ebay, of cameras that I could not afford in perfect state, and solve problems that would be impossible otherwise to solve. To fix something in place when it fails, instead of having to give up the shooting entirely. And of course I'm having fun with it, getting to know cameras and all their internals is interesting and fun. Think of it as work out for my brain and skills, just like jogging. And in the end, at least for me, very rewarding!