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Step 2: Clean It

Unfortunately, these lenses were usually stripped out of equipment with the minimum possible level of care, so the odds are you'll need to do a bit of clean-up.

Because the lens was mounted inside expensive equipment, it probably lived a sheltered life before being ripped from its home. The lack of a focus mount also means the lens block didn't have air sucked through it during focus. The happy result is that despite a filthy exterior, there probably isn't any nasty stuff between the lens elements. There are probably fingerprints on the outer elements, lubricant (graphite dust) on the mounting threads, etc.

My lens had a cardboard strip glued around the front, which I first removed by scraping underneath it using a box cutter. I used artist's oil paint thinner with a non-scratching kitchen cleaning pad to soften and remove the remaining glue and other nasty stuff on the lens body. Then I used paper towels to wipe-off the thinner and a paper towel moistened with soapy water to remove any traces. Finally, I used cotton-tip swabs moistened with alcohol to clean the lettering and threads.

None of that should touch the glass. Clean the glass by first giving a few puffs from a blower to remove dust (which might otherwise scratch the elements). If there are greasy fingerprints, use lens cleaning wipes or a swab moistened with alcohol to remove them. I like to do final touch-up using a lenspen.

Through all that, you should never have the lens elements or body wet -- using too much of any liquid can allow that liquid to seep inside the lens. Considering the kind of equipment these lenses often were used in, I recommend treating the crud as potentially toxic "medical waste" and taking appropriate care in dealing with it.

It has been rumored that some of these lenses might have become radioactive due to exposure to X-rays. More likely, they deliberately might have used slightly radioactive materials in their glass, like the famous Takumar 50mm f/1.4. If they are radioactive at all, they should not be particularly dangerous in normal use... but I wouldn't keep one in my pocket 24/7 (not that it would fit).
<p>impressive..so many lenses out there on surplus; with idea s like yours, they would be useful again,</p>
Thanks for this great tip, I ordered a Kowa 1:1/55 right after reading and haven't regretted it. I noticed (as your images show) that it has a sort of light-bleed towards the edges. Light seems to get smeared away from the center of the image.<br> <br> Here is how I was able to fix this: On my lens, there were three screws on the back (the part that touches the camera) so I unscrewed them and found that the back piece of the lens could be completely removed (removing a couple of the lens elements along with it).<br> <br> When I tried the Kowa with the real piece removed directly against the camera body, the focal plane was a good 10 feet from the camera. At this point you can move the lens further away from the camera body to bring the focal plane closer, but you will also be losing quite a bit of light.<br> <br> So I further modified the lens by using a 10x opteca macro lens attachment between the lens and the camera body. This brought my focal plane right back up close to the camera allowing me to take very similar macros to the original Kowa lens, but without the light bleeding (and, of course, a ridiculously thin depth of field).<br> <br> I have been amazed at the low light performance of this setup (which I believe is better than the Kowa on it's own). I was able to shoot 1/100 on ISO 100 with a single 60W incandescent room light using a Canon 7D.<br> <br> I've really enjoyed this attachment ever since buying it 5 years ago: http://www.bhphotovideo.com/c/product/825023-REG/Opteka_OPT10X72_10x_High_Definition_II.html<br> <br> This was always a great lens attachment (as far as lens attachments go), especially before I owned an actual macro lens. With four elements it works much better than any single element macro attachment. And though I haven't used it much since I bought an actual macro lens, it has proved to be one of the most useful elements in my exploration of DIY lenses as it seems to have very different focus properties than single element macro attachments.<br> <br> In fact, you can even used this attachment as a &quot;attachment&quot; as it's own lens: I happened to have a Canon attachment for a spotting scope which included a 2&quot; extension tube so I simply stuck the opteka onto the end with some sticky tack. This works very well as a super fast macro lens. And because of how thin the attachment is, you can use a shorter extension tube and actually achieve infinity focus (which would only be possible on the Kowa if you had the skills / equipment to cut off some of it's length). This could also be easily turned into a tilt-shift!<br> <br> Anyway this comment has gone on too long, I hope someone finds it helful!
Oh- that is so VERY COOL! <br> <br>I have several OLD barrel lenses [large format, 360~500mm] I have acquired over the years, and one was mounted on a long aluminum pipe with a camera mount on it, probably made it about */- 800mm focal langth [?]. <br>Not too stable, though. <br> <br>Always wanted to put it on my Nikon D700, but couldn't figure out... <br>Thanks!
I have an Apo Goerz lens from a 30&quot;x40&quot; vacuum-back copy camera that also has a very long focal length (and slow aperture, unlike the lenses in this Instructable). However, the long focal length means it can focus to infinity on a DSLR.<br><br>Thus, my mount for it consisted of a custom back for a 4&quot;x5&quot; camera to mount my 35mm SLR (I did this long before digitals) and a custom lensboard to extend the lens way past the normal maximum extension of the 4&quot;x5&quot; bellows. Very scary to use and not really worth the trouble for the IQ, but impressively huge and strange to look at. :)
Whoops, sorry about that ProfHankD! I just read the intro and went straight to looking at your pictures!
Actually, the stated f/ will only be at the designed specifications of the lens itself. A lot of these lenses have an extremely short back focal length. So, if your camera has a lens-mount to sensor distance of say 43mm and your lens has a back focal length of 15mm then the projected image will be larger than designed and the amount of light hitting anyone area will be reduced. Similar to a macro lens will have you have to increase exposure the higher your magnification.<br><br>The lenses will still be fast, especially for the money, but not as fast as one thinks.
This already was explained in step #3.<br><br>Here's the math. The effective focal length of a lens typically is increased by the extra distance that the lens is moved from the film/sensor plane when focus is set closer than infinity. An Xmm lens that is f/Y and moved Zmm more distant from the sensor still has an aperture of (X/Y)mm, but now has effective focal length of (X+Z). Thus, the effective f/number would be (X+Z)/(X/Y).<br><br>Close focus using a lens designed for your camera typically will have the same impact on it's effective f/number. The most common exceptions are lenses that have internal focus mechanisms that cause them to change focal length independent of the distance to the sensor, and even for them there is usually a similar effective change in f/number at close focus.
Good work!

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Bio: I'm an Electrical and Computer Engineering Professor at the University of Kentucky. I'm probably best known for things I've done involving Linux ... More »
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