Extention tubes... or macro lens

[VideoFred]

As some of you you might know, I use a 35mm lens with extention tubes for my filmtransfer unit, now.

What do you think.. can I expect much better (sharpness!) quality with one of these lenses: http://www.navitar.com/zoom/machine_vision_products.htm

Fred.

PS: testing one of these right now:
http://business.lieske-elektronik.de/pr ... 724718.htm

Color temperature is 4100K, UV block, low heat.
First results: white balance is more easy to set.

[skahde]

What do you think.. can I expect much better (sharpness!) quality with one of these lenses: http://www.navitar.com/zoom/machine_vision_products.htm

I would at least try a small-format enlarging lens like a 35mm or 28mm Componon or Radagon. They are going for next to nothing on that auction site and although you will be using them out their optimal range they should easily outperform any taking lense for your application.

best

Stefan

[Sparky]

I'm using something like those Navitar zooms in the first range on their page, but made by Optem. But I can't answer your question- you'd have to compare yourself- could you get one to try before you buy? They are very expensive I think- I was very lucky ;-) Mine seems to work very well but my transfers aren't really very sharp, but I think its the camera/capture/PAL/DV/video in general rather than the lens. They do seem evenly (un)sharp accross the frame though if thats a problem you are seeing.

Mark

[VideoFred]

Stefan,

What's the difference with my normal 35mm lens?
Do you have any links for me?

Fred.

[VideoFred]

Sparky,

So you are using one of these high end lenses...

This is the sharpness I get:
http://users.telenet.be/ho-slotcars/testmap/sailing.bmp

This is a not manipulated frame...
Is this about what you get, too?

I wonder if this is real sharpness of 8mm film.
Good Workprinter transfers are sharper.

I also wonder if the condenser lens works as an optical sharpener, in some way.

Fred.

[Sparky]

I think thats actually sharper than what I get, but it may be the higher res you capture. Don't most peoples workprinter cameras have sharpening built in? I just found out the camera I'm using retailed at about 5000 euros 8O not long ago! (I was very lucky there too ;-) ) so It's a decent quality camera.
I can't use the iris on the lens as it vignettes so all my captures are wide open. I need to ring up Optem and see if they can help- those lenses are very modular and I think I'm meant to have a camera coupling section that would probably help. If you like Fred, and pay the postage, you can borrow my lens for testing, but I guess it would need a fair bit of rigging into your setup. Its c-mount.

Mark

[VideoFred]

If you like Fred, and pay the postage, you can borrow my lens for testing, but I guess it would need a fair bit of rigging into your setup. Its c-mount.Mark

This is a very generous offer!
Of course I accept it, and pay for the postage.
My cam is C-mount, too.

I PM you.

Fred.

[VideoFred]

I can't use the iris on the lens as it vignettes so all my captures are wide open.
Mark

This is the reason why you don't get good scharpness, the iris should be set somewhere in the middle for optimal results. You are using a good diffuser for your back light source?

Fred.

[skahde]

What's the difference with my normal 35mm lens?
Do you have any links for me?

Enlarging, macro or process lenses are optimzed for reproduction of flat objects while taking lenses most often have some curvature of field which is not much a of a problem with 3D-objects in front of a camera but with a flat piece of film. Furthermore, most 35mm lenses are optimzed for highest contrast at a resolution of about 20-40 lppm (they do resolve more but the contrast declines) whereas lenses optimized for reproducing smaller formats or for higher magnification ratios (which in the end means the same) should peak at higher resolutions if the manufacturer did his homework. With S8-frames as your source and PAL as your target three times the resolving power of an excellent 35mm taking lens is not wasted.

Here is an example for a 18x24mm enlarging lens from Rodenstock. The price is completely nuts, though (paid 25 EUR for my sample):
http://cgi.ebay.com/Rodenstock-Rodagon- ... dZViewItem

Another one, this time from Schneider and priced more reasonable:
http://cgi.ebay.com/SCHNEIDER-35-MM-F-4 ... dZViewItem

Another option are Micro-lenses available from a range of manufacturers but a bit more expensive:
Examples:
http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... Track=true[/url]
http://cgi.ebay.com/LEITZ-WETZLAR-25MM- ... dZViewItem[/url]
Overview:
http://www.a1.nl/phomepag/markerink/microlen.htm

Downside of all these lenses is that they have no means for adjusting focus but in a fixed setup this shouldn't matter too much.

Stefan

[VideoFred]

Stefan,

Thanks for explainig and for the links.
Just to understand each other:
My lens is 35mm focal lenght, but special designed for digital imaging.
It's not a lens from a 35mm analog photo camera.

One more last question:
Suppose it was your system and suppose price was not important.
1/3" CCD machine vision cam, 1024x768 pixels, C-mount.
Distance between film plane and CCD can not be less than about 100mm.
Super-8 film frame is about 6 x 4 mm.
What lens would you use for optimal results?

Fred.

[audadvnc]

Are you reversing your lens direction? Often with macro photography you turn the lens around, so the mount faces away from the camera. This solves much of the flat-field versus curvature of field issue. A low power microscope objective, for instance, optically resembles a reversed camera lens.

[ccortez]

I've been considering an analog camera head for the improved color space, then into matrox rtx 100, then maybe into decklink card?

I just have no idea what to look for or how to search ebay for such things. All my terms are far too general to narrow down search returns, and I don't know any suitable makes/models.

Haven't thought it through yet, and this may be the wrong thread. But all the right people seem to be here. ;-)

[audadvnc]

You might look into a used pro-level 3 chip 2/3" camera such as a Sony M-7 or DXC-537; they're getting quite cheap for what used to be $10K cameras. You'll need a CCU to white balance it manually.

Take a look at the Greene Sheet for price and availability of good used pro video gear:

http://www.bstock.com/

[ccortez]

Something like this?

http://cgi.ebay.com/Sony-DXC-637-Camera ... dZViewItem

Maybe MovieStuff will chime in here... but it seems to be there would be advantages in using a rig like this for WP transfers if I could preserve the analog signal characteristics into an uncompressed card in the PC.

The Matrox systems have component in/out, right? (OK, that I can look up myself.)

[skahde]

My lens is 35mm focal lenght, but special designed for digital imaging. It's not a lens from a 35mm analog photo camera.

What lens exactly and what is the size of the sensor in the camera it was made for?

One more last question:
Suppose it was your system and suppose price was not important.
1/3" CCD machine vision cam, 1024x768 pixels, C-mount.
Distance between film plane and CCD can not be less than about 100mm.
Super-8 film frame is about 6 x 4 mm.
What lens would you use for optimal results?

I don't know... but may I take the numbers involved and jiggle a bit? Maybe afterwards we both know better what exactly to look for or why you shouldn't have asked

Looking at the CCD-camera in question and its sensor with 1024x768 pixels on a rectangel of approx. 6 mm across you will need a lens which will resolve above 200 lppmm (5µ linepairs) with good contrast. As you are reproducing by about an 1:1 ratio from S8 to 1/3" (6.3 vs. approx. 6 mm across the frame) this will be more than good enough for capturing from film and you won't be limited too much on either size.

With a minimal distance between lens flange and CCD of 100mm your 35mm lens should reach a minimum reproduction ratio of 1.86:1 so I guess you are using a retrofocus design for an SLR with longer backfocus.
To reach 1:1 or smaller with a symmetric design, which is preferable because of less distortion and flatter field, you will need at least 50mm of focal length.

Another factor to consider is diffraction and what f-stop will be the smallest to use before resolution declines. With 5 um linepairs circle of diffraction should not exceed 2.5 um and here we come to a problem: You must not stop down beyond 1.88 to exceed this circle of diffraction. Looking a real world lenses stopping down a bit may enhance contrast enough that the overall picture looks sharper even if it has less detail, though.

There are, however, high resolution lenses which seem to fit the picture. For example the Zeiss Jena Tevidon 50/1,8 a high resolution video lens which made it into the Macro-Lens database http://macrolenses.de/ml_detail.php?ObjektiveNr=131
or the Apo-Computar 55/1,9 http://macrolenses.de/ml_detail.php?ObjektiveNr=192 which unfornutaley is as legendary as it is expensive on the used market.
Another option are fast process lenses like the S-Nikkor 50/1.4 http://macrolenses.de/ml_detail.php?ObjektiveNr=37 or another Nikkor, the Ultra-Micro-Nikkor 2/55mm http://www.naturfotograf.com/ultra_micro55.html. To choose the best performing lens I would not look for brand names, buy a handfull, starting with the cheapest with the right specs, test them head to head and sell the loosers.

best

Stefan