Lens recommendations for special application

[mark_blum]

<p>Hello,<br>

I have an unusual lens requirement and hope someone on the forum may have a suggestion. </p>

<p >Specifically, I am searching for pairs of small diameter (in the 14mm to 24mm diameter range) lenses in these approximate focal lengths: 114, 125, 133mm. <em>Ideally</em>, the diameters would be F=114, 14mm dia.; F=125, 18mm dia.; and F=133, 24mm dia., but somewhat larger diameters can be accommodated with some grinding to flatten one edges (for suitable spacing of the lenses in a stereo camera). They must all cover a 24mm x 36mm CMOS sensor (42mm diagonal). </p>

<p >The lenses can be quite slow and don't need to focus or have an iris. In fact, I plan to remove all that if present and use just the optical blocks anyway. I will use the lenses only in macro range, extended some distance from the camera sensor. </p>

<p >I have identified some available lens options for the 125mm focal length (between 12 and 24mm diameter), but they are not as high resolution as I would like. I found there is an Ilex anastigmat 4 1/2" (114.3mm) lens only 3/4 inch diameter. Sounds perfect for me, but have not found a sample to test yet. </p>

<p >If you can provide any suggestions or avenues for further research, I would be most grateful.</p>

<p > </p>

<p >Thanks,</p>

<p >dddiver</p>

[mike_earussi1]

<p>It would probably be helpful if you stated what you are trying to do, but I can tell you that Ilex anastigmats are not the highest quality of lenses. Have you thought of using Bolex or some other brand of 16mm movie lenses? They would be of higher quality and might be small enough for what you're wanting, though they may not cover 42mm diagonal completely.</p>

[leicaglow]

<p>Most lenses with smaller f-stops are going to lose resolution at that small of aperture, so it would be good to know what you're trying to do.</p>

[erie_patsellis]

<p>At the least, ideally we need to know sensel pitch, expected final image size, magnification, etc. There are numerous lenses available that could meet your needs, but without knowing what lens resolution is required, ideal aperture, etc. we're just shooting in the dark.</p>

[mark_blum]

<p>Hi all, and thanks for your questions/suggestions. To respond, I am imaging on Canon 5D MK II 24 x 36mm CMOS sensors. Pixels are 6.4 microns. I will be using fixed apertures (for taking, not for viewing) as follows : 114mm, f/45, 125mm f/38, 133mm, f/32. I know there will be serious diffraction. I hope for lenses that will have enough resolution to be diffraction limited at these apertures. But I am finding very few lenses small enough to fit my requirements in this focal range, so can't be too choosy. As I said, <em>ideally</em>, the outside lens diameters would be F=114, 14mm dia.; F=125, 18mm dia.; and F=133, 24mm dia., but somewhat larger diameters can be accommodated with some grinding to flatten one edge of each lens so two lenses can be placed closer together. The lenses will be used at fixed focus distances, all very close (within 2 1/2 feet). No infinity focus is needed. I prefer lenes in barrels as opposed to shutters. Otherwise, if in shutters, the elements may need to be refitted in a new barrel when removed from the shutter, an unnecessary complication.<br>

I understand the 4 1/2 inch Ilex Anistigmat is not great quality, and would love something better, but so far it's one of only a very few lenses I have identified that meet the stated focal length and diameter requirements.<br>

Thanks for any specific lens suggestions you may have.</p>

[erie_patsellis]

<p>I think you will be unable to source lenses with those apertures, quite frankly you are going to be so diffraction limited that it will become an excercise in frustration if any level of sharpness is required. I would reccommend you head over to Edmund Optic's website, as well as finding a few other optical suppliers and looking at coated achromats, you should be able to find a 125mm f.l. easily enough, the others may be more difficult.</p>

[mark_blum]

<p>Erie,<br>

Thanks for your comments. I tested coated achromats and their performance was not satisfactory off axis. No where near to diffraction limited. Perhaps custom designed air spaced doublets would be better, but lens designers are telling me that the only real solution is multi-element lens. I am going to look at cine lenses too.</p>

[kelly_flanigan1]

<p>To get better performance off axis you need a better more complex lens; if normal lenses are used with spherical surfaces. A TESSAR design to cover 24x36mm with a 114 to 133mm focal length will work well; that is not much angle to cover off axis.<br /> <br /> ****Since your useage is macro; a normal off the shelf camera lens may or may not work ok. An enlarging lens might be better.<br /> <br /> *** If the sensor is 24x36mm and the lens are 114 to 133 mm; what is the subject size (s) so a person can figure what you mean by *macro* ? The term macro is al loose term. If one mentions the subject is size(s) one can figure the *ratios*; thus there is no guessing!<br>

<br /> <br /> ***A common 127mm F4.7 Kodak Ektar is a very fine lens; common on 4x5 press cameras. Its usage goes back at least 70 years. It is really a lens for 3x4" usage; but works well too with 4x5"; if the print is say only 11x14 to 16x20. The *far* corners of a 4x5 frame are weak; say dowwn to 15 to 18 line pairs per mm; at the far corners of a 4x5" frame. On axis; I have had some 127mm measure in at 85 line pairs per mm on axis. The central region of 6x6cm frame is on par with a Hasslblad wen the lens is say at F11 .<br /> <br /> A far bigger issue is you mention macro; and are boxing in the outer diameters too.<br>

Enlarging lenses work well with macro; well corrected ones such as Schneider Componon, Rodenstock Rodagon, Nikon El Nikkor come in 105mm and 135mm focal lengths; and are being given away on Ebay at a tiny fraction of their old cost. You are not going to be able to custom design a lens as good ass any of these for a small project. In fact with an old microfilm camera I worked on for check sorters; we used enlarging lenses as the "taking" lenses.<br /> <br /> In still LF stuff their is the 150mm F9 Rodenstock Ronar which works well close up too;<br /> <br /> There is the old Kodak Ektar 203mm F7.7 LF lens which is tiny; and very well corrected for closeups too.<br /> <br /> In Xenar/Tessars there are ones in the 105mm and 135mm sizes in you tarrget area; of many differnet Fstop sizes; depending on when they were made. ( the 127mm Ektar is of a Tessar design too)<br /> <br /> A common 105mm F2.5 Nikkor for the Nikon F series of slrs is great; the ones after about say 1970/1' are of a gauss design; a tad better for closeups. The *pickle* is the they exceed your max diameters.<br /> <br /> A bellows type 105mm F4 Nikkor for Nikon F s great for macro usage; but they are abit costly.<br /> <br /> A common 127mm F4.7 Ektar is what I would try; they are easy to find too.</p>

<p>The max diameter criteria boxes you in alot; thus I culled out alot of great lenses.<br>

There are *boatloads* of TESSAR type designs in the target focal length. Some are on dumb old Polaroids; old Kodak Folders too.</p>

 

[kelly_flanigan1]

<p>Here with a 50 megapixel 4x5" scan back I used a 127mm F4.7 Kodak Ektar from the mid/late 1940's.<br>

<br /> It is a single coated lens; Normally I use a 135mm F5.6 Componon as a shooting lens for copy work; it was apart for cleaning.<br>

<br /> In this rush application I used a 127mm Ektar; which worked ok because the texts/details were all in the central core; ie on axis.<br>

<br /> The scan back only covers 7x10cm; ie like what folks new to digital call today cropped.<br>

<br /> In this application the bags are 3D; they would not go thru a scanner.<br>

<br /> The biggest bags were so big that a 35mm dslr would not have enough resolution to read the dinky type; and get the entire bag in the image too.<br>

In the actual full image; one can see the grain/fibers of the bag; not bad for a lens made when Truman was president and B36's were the top bomber.</p>

<p><img src="http://i4.photobucket.com/albums/y148/ektar/16mm%20Nikkor/PhaseOneScanARROW.gif?t=1267622026" alt="" /></p>

<p><img src="http://i4.photobucket.com/albums/y148/ektar/16mm%20Nikkor/UntitledTake26bagcrop.jpg?t=1267621796" alt="" width="676" height="564" /> <img src="http://i4.photobucket.com/albums/y148/ektar/16mm%20Nikkor/16MMPOWERPHASE4X5SPEED.jpg?t=1267621659" alt="" width="700" height="465" /></p>

[kelly_flanigan1]

<p>Mark; a Mamyia C series TLR body's lenses has lenses already in pairs; matched even by focal length.<br>

Thus a 105mm F4.5 could be another lens assembly to consider.<br>

<br /> Far up the thread you mention way closed down fstops of F45; F38; F32 for a 6.4 Micron Pixel site.<br>

<br /> With my smaller 4x5 back that is only 35 Megapixel; it has a giant 14 Micron pixel site and using F32 limits the image; I usually use F8 to F16 with a good lens. The 50 Mp back has a tighter pitch; maybe 12?.<br>

<br /> With F45 and a 6.4 Micron Pixel size; it is like placing a lawn mower carb on a sports car; abit of a mismatch!<br>

<br /> One is not going to get the performance one thinks!</p>

<p>You are probably shooting a closeup of a 3D object; and thus are stopping down to get DOF.</p>

[mark_blum]

<p>Hi Kelly,<br>

A common 127mm F4.7 Ektar is a good idea, but still too large. It's intended for a macro stereo setup. At that 127mm focal length, I need to be able to reduce the lens centers to 18mm. I forget the 127mm F4.7 Ektar diameters, but my recollection is they are up around 28mm or more. Then the only way to use these is to either disassemble them, grind down each element individually to under 18mm and rehouse all elements in a new barrel (way too much work) or grind one side of each lens flat, so they center to 18mm. Is there enough "meat" on the 127mm F4.7 Ektar to allow that?</p>

<p>Here are some other candidates I have looked at. Both would require some grinding of lenses to flatten one side. This might be possible, becasue the optical elements are quite a bit smaller diameter than the lens barrels.</p>

<p >Carl Zeiss Jena Goerz Dagor 125mm f 9 wideangle lens: the front outer dia. of the barrel is is about 32mm and the rear is about 28mm. I need 18mm at this focal length.</p>

<p > </p>

<p >GOERZ APOCHROMAT ARTAR 4 INCH (F = 100mm) F: 9.5 LENS NO. 764183. The filter thread in the front is 20mm in diameter and the rear is 17mm in diameter. I would have to reduce to 14mm diam. It's fl is too short, so would need a diopter to get effectively F = 114mm.

<p >Your thoughts and suggestions are greatly appreciated!</p>

<p > </p>

<p >Mark</p>

</p>

<p >

 

</p>

[kelly_flanigan1]

<p>Hi Mark;<br /> <br /> ***OK some dumb questions here for clarity:<br /> <br /> (1)I assume the reason for small lens diameters is so the the left and right pairs do not touch together?<br /> <br /> (2) I assume the choice of focal length make the working distance not be too short?<br /> <br /> (ie if one used dumb common 50mm F4 El Nikkors which are Tessars one would have smaller lenses elements<br /> A collapsible Russian Industar-22 or 50 is already in a dinky tube ; the ones for Leica Thread Mount.<br /> <br /> (3) is there so target magnification you have?<br /> <br /> (ie for a 24x36mm sensor; what is the field; ie is it say 4 times; ie 96x144mm?)</p>

<p>Of course both a 50mm or 100mm lens could be used for a 96x144mm object at 1:4 ie sensor: object<br /> and the working distance of course will be about twice as far away with the 100mm scheme; one has a less 3D effect of the Roswell Aliens's face :)<br /> <br /> I sure would try an off the shelf enlarging lens than trying to grind down elements and make new lens blocks.<br>

There is also a 113mm F4.5 Printing Ektar from the 1960/70's; it is radioactive.</p>

[kelly_flanigan1]

<p>One the low on old folders one has the 100mm F6.3 Kodak Anastigmat<br>

<br />****A cheap lens would be famous Polaroid Swingers 100mm F17; but it is only a single element!<br>

<br /> A Polaroid 100 /101/102 /103 uses a 100mm F8.8 glass triplet; now that might be cool!<br>

<br /> The model 104/220 has a 114mm F8.8 2 element molded plastic lens.<br>

<br /> Colorpack II 114mm F9.2 3 element some are glass; some are plastic</p>

<p>The old Highlander Polaroid ; ie model 80 uses a 100mm F8.8 lens; 3 elements glass too.</p>

[jim_galli4]

<p>All of your numbers are plus or minus f7. You're looking for Goerz Dagors. Very sharp, long history and many many focal lengths over the years. I've had 125mm dagors before. Have a 102mm right now. There was also a 114mm Wollensak that was a wide angle lens f9.5 or so that might fall into your range. Very sharp in the middle which is all you'd be using. Some of the old Kodak Folding cameras focused at about 114mm. Some of the lenses they used were very good. Some weren't. Weird project. Good luck.</p>

[brian berry]

<p>You might look into this: in the 30's or early 40's, Ed Land, the Polaroid founder, made an 11x14 inch STEREO view camera for a famous art historian. This was Clarence Kennedy of Smith College. Kennedy used a long f4.5 Tessar lens, just one, but employed a waterhouse stop pierced with two very small apertures. The dark chamber of the camera was divided by a fore-and-aft panel. Each exposure produced two 5 1/2' by 7" negatives on a single sheet of film, subsequently contact-printed. <br>

Kennedy photographed Italian sculpture with this camera. He distributed contact prints--stereo pairs--to colleges. I mounted a show of these at Yale in 1968, so I know that the Yale art-history library has a set. He too worked exclusively at very small apertures--45 at least--but of course, he was contact-printing. As I write this, I have in front of me "Photographs by Clarence Kennedy," Published by Smith College in 1967 and printed by Meriden Gravure.<br>

Included in the extensive bibliography of Kennedy's publications are two that probably go into detail on the techniques and principles involved: "Stereoscopic Photography," Kennedy and Willard Morgan, which appeared in Collier's New Encyclopedia, 1961 Edition, Vol 15, pp 365 and 366. Also, "Sculpture Photography," in "The Complete Photographer," National Education Alliance, Inc., 1943, Vol. 9, pp 3190-3199.</p>

<p>I was doing stereo work in those days with a 6-inch Red Dot Artar at magnifications from 1:1 to 4:1. I got the separation by using the sliding front of Linhof Color View. Easy. My subjects weren't moving, and the stereo pairs on 55PN Polaroid were immediately checkable, of course. That Artar was reasonably sharp at f45.</p>

<p>I believe the camera itself was in a Polaroid corp museum as recently as 1979. I heard a rumor recently that the camera has been moved to the Boston Museum of Science in Cambridge.</p>

<p>I never understood the principle of two apertures on a single lens, but then I ever played with it, either. Just my .02 USD. Good luck</p>