I had to have a few more attempts: same set up as in the last photo. A stack of 25, of a Silver dollar sized medal(this shot really recommends the technique IMHO):
I did some testing of the Venus 2x and found that it was not telecentric at 2x. The technique was to simply measure the distance on a calibration slide, then move the ref plane and measure it again. Any fixed object distance can be measured. If the scale does not change between measurements, the lens is telecentric. I verified this technique using the Nikon MM5x objective, which is known to be telecentric. I did not see even a single pixel of scale shift over a 150um Z-range. I published the results over on PM forum in my Venus 2x review thread...Ray
Contact me for photographic equipment or visit my home page at: http://macrocoins.com
Thanks I had a quick look on ebay for a calibration slide. I found there were direct types. What sort are you using? I presume I can place the calibration slide anywhere in the optical path(I was thinking immediately behind the SK( thats the easiest most secure place). I had some of my questions answered ( by my self) I was very please to get some use out of the SK but I was really wondering was it actually doing anything I had never thought of using such a set up to bring the SK,s minimum focus down. My main concern was whether I had just created a fancy set up that looked interesting but was not really performing. The 200% crop was the one piece of evidence that told me I had a truly useful optical system system( even if not telecentric). The minolta 100mm F$ bellows lens on its own can not produce such resolution, while the SK on its own has such a long lens to subject distance( around 80cm) on a single bellows that it was impractical. Putting it on two bellows did help but introduced so much vibration into the optical path as to be useless.
It will take me a couple of weeks or so to get a calibration slide( When I know which sort is best).....I will post the results when I have tested the set up.
austrokiwi just wondering have you done anymore testing on this type of photography. I have enough lens. I also have a extra bellows coming. I am going to put one of these together and try it as well. I also found some more threads on google on this topic. there is also a listing for a lens manufactured for this type of photography. I want to build my own like you did. I will do this later this fall. I will post the images when I get this built and see how it goes great thread you did a great job on your images. I find more and more I like to learn as much as I can about this stuff. have a great one
I struggled with getting repeatable results. I think it was a case of beginners luck. my problems in getting the set up correct each time lead to me looking at the Rhinocam
austrokiwi yes after watching the video s on these new lens and how they work. I can see why you would purchase the rinocam. the lense in the video they demo. they don't even connect a camera to the lens just wires and watch the computer monitor to do there focus the lens. the lens is mounted solid. everything else is done by the computer and your mouse. I like what they are doing and this lens system would be great for coin photography. have a great one
austrokiwi have you watched that video on coin photography. the lens they are using will do a coin up to 3 inches. that's a large coin if you get a chance. if you have not seen the video take some time and go watch it that lens is amazing. the image fills the monitor what a great way to check coins for error and variety. one can set back and just watch the monitor. the bigger the monitor the more you see the coin. have a great one
"Navitar designs and manufactures a wide variety of high magnification imaging optics for a broad range of applications including the biomedical, nanotechnology, semiconductor and electronic imaging industries. We provide leading equipment manufacturers with highly repeatable and automated precision optics that can be designed into new instruments with smaller footprints and lower prices than older equipment"
aardspeed great you found other links. wish I knew how to attack links here. I watched a video last night of how to mount the lens and focus the lens. there monitor was a laptop with a large screen. I think the camera was no bigger than 2 centimeters. it was inside the cable that connected the lens to the laptop. I like to get my hands on one of these and take it apart. I don't see why a person could not build one of these lens. if I can find the same site. I was on last night they had up a sketch of the construction of one of these lens. I would like to see how it made again. if you find a link please share that again thank you aardspeed.
ray thank you so much. I want to go farther thank you. I appreciate all your help. ray I did it just got it all together telescentic focus. I used a Nikon 135mm mounted on the bellows. the camera on the end. I mounted a 105 enlarger lens. for this test on a second bellows. my mount was not solid enough. but I got it focused. but I did not dare click the mouse to take a picture. I have purchased a 300 mm enlarger lens its coming. when I got the nickel focused all I could see was the beaver head. the contours and shape was as it should be. ray love this stuff. I will build some thing stronger and get pictures have a great one austrokiwi. I had put this all together. my mount was way to weak. but I know now how it works. the focus is very touchy. nothing can move once in place. austrokiwi no they have a lense and the cable is the feed for the camera. there is a video to demo this new lens. I don't know how to attach videos here have a great one
Rocky well done......I think you are more patient than I am. From what you have stated you are experiencing what I did...very touchy focus. At the moment I am a little frustrated with my rig. the column on my copy stand is now a major liability. The camera arm mount just isn't stable enough.....End of the month I get a replacement column( when the budget allows). In the mean time I am replacing the base board in preparation. The replacement is a 60cm X 60cm X 3cm (23.6 inches X 23.6 inches X 1.18 inches Slab of Granite. The slab weighs 29 kg ( 64 Lbs) at the moment the challenge is drilling the four holes.....I practiced with a granite tile. One drill bit per hole( and lots of water)....the slab cost €9.00 suggests to me each hole is going to cost about €5.00 and an hour in time. The weight of the slab will act as a vibration damper. The total cost of the base board will equate to about US$32.00 that's in comparison to the standard baseboard cost of around US $140.00 {Edit it only took 30 minutes for all four holes and exactly four drill bits( one for each hole) seems the drill bit I used for the practice run was not the right type.}
The column I am getting is code number 4476 on the page below I didn't go for the column with fine control as I use a modified Olympus CH2 microscope as an X,Y, Z stage. I also have a stack shot system making the Kaiser fine focus option a waste of money
austrokiwi wow very nice rig. I know exactly what you are doing. using granitite for damping. I use to work air patrol from a helicopter. once a year we would do a complete thermo vision of the power lines. we had to get the our company engineers to come with us on a patrol. the engineers designed a system for the helicopter. to balance and stabilize. the thermo vision camera where we pointed it out the rear window mounted on a plywood platform. austrokiwi. something to think about if you will. I am going to build a slimier mount. the vibration inside a helicopter is off the scale. when the engineers was done designing this mount. the camera never moved a bite. there was zero vibration. I will build this mount later this year. I will share pictures with you so you can see what it looks like. I would also like to see what your rig mount will look like when you are done have a great one
arrdspeed Do you mean like an endoscope type camera? I would have to say you are probably right arrdspeed how else could it work connect a cable. the cable has the camera scope and that how they would adjust focus in the video. right where it attaches to the lens. I see if I can find that video again have a great one
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Posted 02/20/2015 4:16 pm
