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01-22-2013, 12:51 AM   #1
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Help cleaning 640mm Noflexar lens tube

Hi, I had the luck to pick this baby up for about $11. The glass seems fine, although very dirty. The lens unscrews from the front of the tube. My problem is with the tube, which was very dirty. I tried blowing it out with a commercial blower I use to clean my computers. This seems to have helped a lot, but after a few shots, and the obvious dust on the censor, I've been thinking of using some tap water to rinse the remaining dust out of the tube, I'm not sure what effect this will have on the aperture mechanism and blades. If anyone can give me some advice on how to remove the remaining dust without damaging the lens, I would appreciate it.

A picture of the lens, with a photo taken from about 60 meters, with my K-x. The shot was wide open at f9, with my normal in camera Jpeg settings, just resized a bit, no cropping or other sharpening





I know the lens was not mounted correctly, I'm still looking for a tripod mount adapter


Last edited by altopiet; 01-22-2013 at 05:43 AM.
01-22-2013, 06:58 AM   #2
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Well the good news is that - at eleven dollars (or even many times that) it's a keeper - even as is.

I wasn't able to get a better (or perhaps larger) view of the pic, but at that size don't really see much wrong with it. Any chances of getting more than one version of a raw file? Also a pic to include as much blue sky as possible?

As for the possible remedies... Would definately not suggest rinsing with any type of water - as this would do considerably more damage than any type of good effect. Water would most likely somehow find it's way further into the lens - possibly around the edges of the elements or other internal parts of the lens.

Also depending upon ones mechanical abilities... Is it possible to very cautiously take apart the lens further? Usually there aren't too many optics of a lens of that focal length. If one is able to do it with a bit of caution that would be a better start to be able to reach as many of the optics as possible. It would be much better to do a proper cleaning of the optics as opposed to using any type of water which would damage both the optics and the lens construction

I've even tried something such as this with a generic labeled Quantaray (former Ritz label) 500mm preset. If I recall correctly it only had three or four optics and all wee reachable with very minor disassembly, but... One would (again) have to use caution to keep the orientation of the optics correct in reassembly.
01-22-2013, 07:35 AM   #3
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QuoteOriginally posted by Medium FormatPro Quote
Well the good news is that - at eleven dollars (or even many times that) it's a keeper - even as is.

I wasn't able to get a better (or perhaps larger) view of the pic, but at that size don't really see much wrong with it. Any chances of getting more than one version of a raw file? Also a pic to include as much blue sky as possible?

As for the possible remedies... Would definitely not suggest rinsing with any type of water - as this would do considerably more damage than any type of good effect. Water would most likely somehow find it's way further into the lens - possibly around the edges of the elements or other internal parts of the lens.

Also depending upon ones mechanical abilities... Is it possible to very cautiously take apart the lens further? Usually there aren't too many optics of a lens of that focal length. If one is able to do it with a bit of caution that would be a better start to be able to reach as many of the optics as possible. It would be much better to do a proper cleaning of the optics as opposed to using any type of water which would damage both the optics and the lens construction

I've even tried something such as this with a generic labeled Quantaray (former Ritz label) 500mm preset. If I recall correctly it only had three or four optics and all wee reachable with very minor disassembly, but... One would (again) have to use caution to keep the orientation of the optics correct in reassembly.
I just discovered that is actually a 400 f5.6, or a 640 f9 lens, you just unscrew a part of the tube, about 110mm, and screw the front, AND ONLY LENS GROUP on again. There are no rear lens group, just the aperture, with more than 20 blades , in the middle, and a bellows at the back, that's probably why the tube is full of dust (it didn't have a rear lens cap on when I got it). You focus by squeezing the "gun" butt to focus, then lock with the round knob at the side, after that you fine tune the focus with a similar button on the bellows. (It might be the other way around, I'm still trying to figure it out, the bellows definitely do not act as macro type feature)
Unfortunately, I only took some Jpegs of the cricket game, as I was in Hi, continuous mode. I'll try a few RAW shots this weekend.

However, I think you have a point, I'll fight the dust bunnies with it on my K-x until it is clean, before using it on my K-30. I was surprised to see these lenses, although probably in much better condition, going for between $500 and $1500 on Ebay. With the results of about 200 shots I took yesterday,and not having another decent lens in that range, I can just thank my lucky stars
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