Fabricating Camera Optical Equipment Lens Adapters

maybe a dig here would yeild something:

Ha - just found the site owner is a regular here!

You need a lens not normally available for a mini board camera???

I suspect that the threads may be metric since most of them are made in the eastern part of the world.

Spec for the sony LO-999CMT C-NF adapter shows the thread type.

M17x0.75 external thread

Dave

Thanks, I've seen Richard's pages, although they seem to be expanded since I last looked, and this is the first reference I've seen for the NF mount thread size, 17mm x 0.75.

Richard's truetex camera/microscope adapters page also has some very good reference links at the end.

Thanks Bob, the specs I've seen for mini board camera lenses are 12mm x 0.5 and the NF mount threads are likely to be 17mm x 0.75.

The mini board camera lenses might be one option if the focal length would be compatible. The board cams I have, have been lent to a friend, or I would have tried the lenses (although some lenses are superglued in place). Those lenses sit fairly close to the image device, so they might not have the optical spacing needed for the SONY XC cam (focal plane, I guess). I won't know about the board cam lenses until I try a couple of 'em to see what they'll do. The majority of them are fixed-focus and fixed-iris (or no iris).

The small factor CS mount lenses that I already have don't fit close enough to the image device to be useful, but they can focus an object at about 1 to

2" away from the front of the lens as an extreme close-up lens.

These SONY XC-777 video cams I have aren't a typical box-type or board cameras. The body is under 1" square and the body length is about 3.5". These cameras are considered industrial cams, and when fitted with the correct lenses, will perform as a normal video camera.

Yep, the threads are going to be metric, and I mentioned 32 tpi as an indicator to suggest that the threads aren't as fine as 40, or as coarse as

20 tpi.

I don't readily recognize metric thread pitches unless I've got a fastener in a wrapper marked with the pitch (just far more familiar with inch threads), and they're not so easy to measure when there are only about 3 crests up against a shoulder or other feature.

Thanks Dave, I have looked at that adapter page, but overlooked the specs pdf.

The numerous C and CS lenses that I have don't seem to work with these cameras, as if the back focal lengths aren't compatible with these SONY XC-777 cameras. These cameras don't have an integral mechanical adjustment for the CCD device.

As I mentioned in another reply, the (C and CS mount) lenses I've tried will only focus in the extreme close-up range of 1 to 2".

Maybe the problem is that I've tried them with the rear lens elements positioned too close to the CCD, considering the appearance of the C mount adapter.

You may be able to scrounge some info from the site below.

Greetings Bill, All the optical threads I've done were 55 degree thread form, not the

60 degree we are all famililiar with, even when the pitch was metric. I believe this is industry standard. Eric

If the elements are too close to the CCD, you will *never* be able to focus.

Being only able to focus in extreme close-up range suggests that the lens is too distant from the CCD.

Just for the fun of it -- stretch a sheet of Kleenex or similar tissue paper across a frame, and hold the lens in front of it pointed towards a window (during daytime). Move the lens forward and back until you get a reasonably sharp image on the tissue. *That* is how far your lens should be from the CCD.

If the lens you are trying to adapt have larger threads than the camera does, you really won't be able to get anything other than close focus.

Good Luck, DoN.

What standard? The only application I am aware of would be the ancient RMS thread used on microscope objectives, which is 55 degree Whitworth. Virtually everything else is a UN or ISO standard 60 degree form.

My customer told me the 55 degree form was standard. And I made many different sizes and pitches for them. All 55 degree threads. However, since I never researched it myself I could only say I believed it was the standard. It now seems that I am wrong. That's what I like about folks like you. You know something I don't and pass it along to me. And, since I have been told two conflicting things it's time I looked into it myself. Thanks, Eric

I'm not sure what might encompass the broad term "optical threads", but I am not aware of *any* standard specific to common optical things using threads, for example camera filters, which seem to be just ordinary ISO

60-degree thread forms in unusual diameter/pitch combinations. If one looks to well-engineered modern components, for example CCD instrumentation cameras with threaded mounts like you will find at then you will see their drawings indicating metric ISO thread designations. The few inch threads such a the 1"-32 C-mount thread are just taken to be vanilla UN specifications, although such examples are more after-the-fact "gypsy" standards than truly engineered specifications. I have more to say about this in my discussion of threads.

I've performed detailed metrology to reverse-engineer hundreds of specimens of optical assemblies from microscopes, telescopes, and medical instruments, and they generally are made with fine metric threads of this sort, as one would expect. If there was some kind of exceptional adoption of 55 degrees for optical parts in general, I would think this would be quite remarkable and widely known. But other than that one bizarre 19th-century Royal Microscopy Society item, I've not heard of it.

At typical optical thread sizes, is a 5 degree difference greater than machining tolerances?

Thanks DoN for confirming that only focusing in a close-up range suggests that the lens is too far from the CCD. I thought that made sense.

I've read about the light from the back of a lens being focused on a piece of paper or similar material (frosted optical flat, I think), and I will try this since it would be a good way to label lenses for future reference.

I was pondering that having some metalworking equipment may allow me to utilize some relatively common lenses for these mini cameras without hacking up some good Japanese optics.

I expect that aside from aluminum, black Delrin might be useful for various adapters, if used cautiously to avoid cross-threading or other misalignment.

Some other optical components I have (eyeglass-type monocular lenses etc) could possibly be adapted to camera lens use for different applications.. microscope or other video conversions.

Thanks, there are some cool accessories there, including several that I didn't know of, such as the adapter for converting video drive iris/DC drive iris, the Auto Iris Amplifier Box.

[ ... ]

Yes -- ground glass being the standard -- I just mentioned tissue paper because it is more likely to be ready to hand -- and you don't need precision for the purpose.

O.K. You want various forms of short-barrel lenses, so you can make adaptors the proper length for your focal needs. A good source for very short barrel lenses would be lenses made for use in enlargers. (Normal short-barrel lenses were commonly used on extension tubes or bellows assemblies to allow focusing to infinity.)

Perhaps -- but what I would tend to use for optical mounts would be a nice free-machining brass. It threads nicely. Thread the ID very fine where you don't need threads for mounting purposes, and then paint in flat black paint to minimize reflections on the ID of the adaptor.

Does your lens do metric threads? Almost everything you do with optics will require metric except some large old camera lenses, and projection lenses.

O.K. A microscope objective would go about 100mm or is it

160mm) or so away from the CCD for nominal magnification. Closer would give less magnification, and probably more distortion. Light will be very low through such lenses.

Enjoy, DoN.

Yeah, I wouldn't object to using brass, since a whole lot of quality optical equipment used to be made from brass.

I've seen threading, black paper and multiple grooves cut into inside surfaces to minimize light reflections, and recently discovered some paper that sure looks like wet-or-dry sandpaper inside a tube section of a machine vision camera setup.

I'll be able to cut metric threads, one of my lathes has the 100 & 127T gears, and the other 2 lathes have other combinations for metric pitches.

I haven't built any optical equipment, but I have some machine vision assemblies that have illumination capabilities, in that an internal light source is added to the optical path to light up the (fairly close) target object. So those illuminators might be helpful where light levels might be a problem. One assembly has numbered cross hairs and the other has a miniature LCD panel in the optical path (but no driver circuit).

Overall, I've acumulated a considerable amount of optical gizmos and odds 'n ends.. lots of binoculars and some spotting scopes, but also quite a bit of miniature stuff.

Thanks again,

Makes me wonder if the engineers who made the drawings assumed they were all 55 degree. A 55 degree thread will screw into a 60 degree thread if things are loose enough. Hmm. Eric