c-mount macro lens for Telecine choices

[Roving6]

I'm considering upgrading my DIY camcorder + Capture Mate telecine system to an HD machine vision camera -w- trigger based system (a'la Video Fred) and am looking for a bit of advice picking out a best value C-mount lens for the machine vision camera?

Is the Computar MLM-3XMP still a good choice @ $327? I'm looking for the best value "sweet spot" - it doesn't have to be state of the art optical perfection, but it shouldn't look like I'm viewing films through a vaseline smeared funhouse mirror either! I'll be transferring vintage Super 8 and regular 8mm films originally made on mid to lower consumer grade cameras.

Nathan

[RCBasher]

For about $100 total, you should be able to get a good used Schneider Comoponon-S enlarger lens, adapter or reversing ring to 42mm "Pentax" thread, some manual extension tubes ( something like: http://tinyurl.com/y8tnof7 I would get two sets for good flexibilty of adjustment range) and a 42mm to C-mount adapter.

If Fred reads this, I'll let him comment on sharpness...he sent me one of his films to transfer so we could compare

If you go to my website (http://www.cine2digits.co.uk) and select the Lenses & Cameras page, the second picture down shows the setup before I reverse mounted the lens. With my 2/3" CCD, the lens performed slightly better reversed. The SMPTE image below came from that lens, click on it to download a full size image. It is straight from the camera and then debayered with ActiveDcam. It will take some sharpening if desired, but probably not needed after downsizing.

Frank

[Roving6]

Thanks for your advice, Frank. Since I'm slightly daft when it comes to optics, I might need you to spell it out a bit more for me if you don't mind.

This is my understanding of the sequence of assembly:

Reversed enlarger lens>reversing ring>extension tubes (42mm Pentax thread style)> 42mm to C-mount adapter> machine vision camera.

The thing I'm most confused about is the reversing ring. It seems like there might be many different styles of things called "reversing rings." Is there anything more specific I should be looking for?

Also, could I do it this way?

Reversed enlarger lens>reversing ring>42mm to C-mount adapter> C-mount style extension tubes>machine vision camera.

BTW, the computer controlled light source in your telecine rig is very clever.

Nathan

[RCBasher]

Hi Nathan,

Two basic methods for the lens mounting:
(thread sizes are for the componon and assume 42mm extension tubes)
Normal way around:
Adapter 1: 39mm female to 42mm male
Adapter 2: 42mm female to C-mount male

Reversed lens:
Reversing ring: 43mm male to 42mm male
Adapter 2: 42mm female to C-mount male
However, unless you have a large CCD in your camera (eg 1/2" or 2/3") it will be better not to reverse the lens.

You could go straight to C-mount extension tubes, but they *may* be harder to find and/or more expensive. 42mm simple tubes are really quite cheap, as you will have seen from the link. It may also be easier/cheaper to find adapters to/from 42mm.

The Componon I have has a 39mm standard thread for enlargers and 43mm filter thread. I originally bought a reversing ring for my Nikor, which has a 52mm filter thread, so for the Componon, it was easier and cheaper to buy a 43mm to 52mm filter size adapter so I could use the reversing ring I already had. Probably more information than you need to know, but just giving you the ideas that you can step up then back down through intermediate sizes if you can't find a direct 43mm to 42mm reversing ring for example.

Hope that helps ratherthan confuses more.

My lighting project has taken a while to get right, but does perform very well indeed now. Working on a combining the capture and lighting control programs into one now...but getting OT here!

Frank
PS In case you go down the 42mm route, beware that Tamron T-mount adapters are 42mm diameter, but not the standard 1mm pitch, they are 0.75mm...so don't go near them!

[Roving6]

I'm clear on the lens arrangement now- thanks for spelling it out.

This lens arrangement is for the 2/3" ccd camera. Will the same arrangement but with shorter extension tubes work OK for a 1/3" camera? (I'm thinking that putting the camera closer to the lens will reduce the size of the image, but I'm thinking that it might also make it impossible to achieve focus.)

Looking at your site, I see you used the reversed 55mm Nikon lens with the 1/3" camera. Would that be a better way to go for a 1/3" camera?

I do appreciate the time you're spending answering my questions. I'm on a tight budget and benefiting from someone else's experience can help avoid expensive experimental blind alleys.

[RCBasher]

For a 1/3" CCD, use the Componon the normal way around. It is different for the Nikon because the later is a taking lens, the Componon an enlarger lens, so they are optimised differently.

S8 to 2/3" requires enlargement, so an enlarger lens will work best reversed as it is designed to magnify an image rather than reduce it.

S8 film to 1/3" CCD is roughly 1:1, so it is a close call for a macro lens which is designed to work down to 1:1 (like the Nikon) as to which way works better.
The final call on reversing the Nikon (performance was almost the same either way on the 1/3" Guppy) was the physical design of the lens. Being a fixed focal length film camera lens, it of course has a focusing barrel. The inner lens assembly itself has a fixed group of elements which are moved as a whole closer or further from the film plane for focussing. It does this via a double helix arrangement between the outer and inner parts of the lens. The net effect is the outer part of the lens is fixed solid to the camera, whereas the inner bit with the optics "floats" in and out via the helical thread. I found this to be a small problem because any projector vibrations would allow the optical part of the lens to vibrate a bit relative to the camera. On the other hand, the filter thread is attached to the optical barrel, so by mounting it reversed I had a tight mechanical coupling to the camera and the outer barrel could float around as much as it wanted and had no effect
No such probems with an enlarger lens!

BTW, it would be remiss of me not to mention I've also tested some APO-Rodagon-D lenses, as recommended by Christoph. They work equally as well and any differences I found between them and the Componon were minor and I would guess that bigger differences may well be found between two lenses of identical model due to manufacturing tolerances. The problem with the Rodagon is finding them at a good price!

Frank
PS

I do appreciate the time you're spending answering my questions. I'm on a tight budget and benefiting from someone else's experience can help avoid expensive experimental blind alleys.

You are most welcome. I've have learnt plenty from others, so a chance to return some experiences to help others is always nice.

[christoph]

not much to add to franks excellent explanation here...

the Rodagon D 1:1 is slightly sharper and has a bit less chromatic errors, but on real world images you'd be hard pressed to see any difference at all, and on a 1 CCD camera the componon-s might even be better suited because it acts as a slight OLPF to suppress aliasing from the bayer pattern.

i just had an email conversation with a macro lens specialist, and he said the novoflex 4/60mm is also supposed to be quite good around 1:1.

with all that said, i think franks componon-s is still one of the best choices because it's affordable and not too hard to find.
++ c.

[Roving6]

Thanks. When I get my telecine rig going I'll post back and perhaps share some results. I'm going to have to pace my spending on this one, so it might be a while, but at least I have some good lower cost lens options!

Nathan

[Roving6]

Well, I happened to find a good deal on the Schneider Comoponon-S lens on e-Bay @ $40, so I took the plunge on that, two extension tube sets a 39/42mm adapter and a 42mm>C-mount adapter. Better yet, certain spouses have authorized the purchase of a machine vision camera!

I'm going to try to use my existing Mac as my telecine computer with the IOExperts firewire camera driver S/W. It's anybody's guess if it'll all work together, but I'm guardedly optimistic.

[christoph]

congrats, very good price on that lens..
which camera are you going to get?

the IOExperts drivers should work, but unfortunately they are quite limited, so i can't really recommend them for anything but a brief first test.

if you want to stay on an all mac solution, your best bet is astroIIDC, which is solid, even if most of the functionality is for star gazing... but the more flexible solution is to get a cheap PC and use this to capture while you use the mac for postprocessing while the transfers are going on.

++ c.

[Roving6]

I'm looking at the Imaging Source DFK 31BF03. The other alternatives are really nice but too rich for my blood. I'm open to other suggestions, though.

Thanks for the tip on the astro IIDC.

Nathan

[VideoFred]

If Fred reads this, I'll let him comment on sharpness...he sent me one of his films to transfer so we could compare

I'm here...

Your transfer was sharper Frank! But I have not tested (yet) your kind of lens on my TIS camera.

Fred.

[RCBasher]

But I have not tested (yet) your kind of lens on my TIS camera.

Well the higher resolution of the IMI will be more demanding of the lens I would think, so given the Componon-S is a much cheaper solution (accepting that we are comparing used prices with new prices of course) then I think this is the way to go.

I didn't mention it above, but the Componon is also quite small in diameter (especially when reversed) compared with a 35mm SLR lens, so getting in close is not too much of a problem. I'm guessing your c-mount macro lens may even be smaller Fred, but certainly the Componon and the Rodagon lenses fit the two Eumig projectors I've tried without any problem.

I'm looking at the Imaging Source DFK 31BF03. The other alternatives are really nice but too rich for my blood. I'm open to other suggestions, though.

Fred has got some good results out of the TIS and it gives reasonable value for money, but you get only what you pay for. For example, the lack of gamma adjustment before conversion to 8bit makes it a no-go in my opinion ;)
From Christophs findings, it looks like PtGrey probably gives the best value while still maintaining basic essential functionality. IMHO, the TIS makes too many shortcuts in order to get the price down. (Sorry Fred, just my opinion for what it is worth ;) )

Frank

[jpolzfuss]

... when you do have too much money, you should go for a "ORYTEC TL-1001 - 8mm TV Conversion Lens":
http://wittner-cinetec.com/aktuell/sons ... e=so_video

Another interesting link:
http://www.muddyfilm.net/cat11/

[VideoFred]

(Sorry Fred, just my opinion for what it is worth ;) )

No sorry needed Frank! But I got my first TIS in 2004 and my second one in 2007. Before you guys did all the testings If I would have to do it all over again, I would follow yours and Christophs advice, if not to expensive.

Fred.