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on Aug 21, 2022 19:18:02 GMT
Last Edit: Aug 21, 2022 19:18:50 GMT by m43yash
Hello All,
First of all, great forum! I have been lurking for several years now and amazed by the width and depth of knowledge of the forum members. Motivated by this forum, I have been using few Yashica lenses on my 4/3 camera. My copy of ML50f2, f1.7,f1.9 and Yashinon-dx 50f1.7 are all great. Especially, the ML 50 f2. Focus peaking and great contrast makes this lens a joy to use. I seek to use ML 50 f2.0 more than anything due to ease of focus peaking.
I love the color rendition of Yashica lenses and decided to expand my collection with a zoom ML 80-200 f4. That zoom lens came with an ML 50f1.4 as a package. The 50f1.4 is a great lens wide open when compared to my Canon 50f1.4SSC, Hexanon AR 50f1.4, Minolta MD 50f1.4 and as good as my super tak 50 f1.4 8 element lens(please don't ask why I have so many 50mm primes).
Only problem is the aperture does not close when I turn the aperture ring. The ring clicks, the aperture lever moves, but the aperture does not close down. The aperture lever springs back and forth moves and snaps back its place, but compared to my ML2 and ML1.7, there is very little resistance to move the aperture lever.
Already I'm in love with the lens wide open. I'm dying to stop this lens down and get crisper pictures. Any help in diagnosing the issue and some pointers to repair procedure will be greatly appreciated. I think there is no other place than this forum for extensive Yashica knowledge.
I searched and found few threads, but nothing that helps me, hence my new thread.
Thank you. I will upload my trial pictures as my second post.
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on Aug 22, 2022 7:19:38 GMT
Posted: Aug 22, 2022 7:19:38 GMT
It could be a problem with the coupling which should be easy to diagnose if you remove the back of the lens, but it could also be the aperture blades are stuck open and need to be removed and cleaned. If you would like it repaired, please get in touch. www.contax-yashica-repairs.co.uk/home#h.5v3txzf9xcok
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on Aug 22, 2022 19:41:38 GMT
Posted: Aug 22, 2022 19:41:38 GMT
I've had the exact same issue with 3 of the 1.4's in the last 2 months, and every one suffered from the same problem... too much oil on the blades. With the limited clearance they have with the holding ring on top of them, they just can't break free of the hydraulic grip from the saturated oil.. If this is what's happening on yours, it will require some work and patience, and some basic tools. It's not difficult to do, but it's delicate work, and not for 'heavy' hands. You absolutely will need a good set of JIS screwdrivers, a lens spanner wrench, and at least one pair of long-legged tweezers - preferably with angled tips. There's also the alcohol for cleaning and something to use as a cleaning cup/tray/etc.
I'd send it to Peter if you're in the UK and you're not comfortable with doing the work -or- if the tool cost exceeds your expectations just to fix a single lens yourself. If you want to perform the same tasks on other lenses, it's more than worth the cost to acquire the tools and hold onto them for just these types of tasks. There are a few places in the US that still do cleanings, but they might get a bit costly these days, depending on where you send it and what their workload is.
If you're up for it, I'll post a short how-to and post a set of links to source the basic tools, or pass on some US repair depots.
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on Aug 22, 2022 22:51:29 GMT
Last Edit: Aug 22, 2022 22:56:29 GMT by m43yash
Thank you Lumiworx for your kind reply. I'm in the US, and I got 50 f1.4 and the ML 80-200 f4 for around $60, so not sure if it is worth sending the lens for repair. Best economical decision would be to repair it myself. Can you please post the short how-to and basic tools? I love Yashica lenses, and I think it would be good for me to perform the repair and learn for future needs.
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on Aug 23, 2022 10:03:53 GMT
Last Edit: Aug 23, 2022 10:12:39 GMT by lumiworx
There are only 2 places I know well enough about their work that I'd recommend in the US, and it's just a guess on charges, but $60-75 would be at the low end, and return times would probably be several weeks. The list of most of the tools I'd used on a haze cleanup for an ML 28-85mm already has most of the links that will work for this too, but I'll add a couple of more recent additions... VESSEL precision screwdriver set TD-56 - $14: www.amazon.com/gp/product/B000CED236/A 2 pack of lockable tweezers/forceps, 1 straight, 1 angled: - $8: www.amazon.com/gp/product/B089G4DW3XThe article I posted on the 28-85mm cleanup w/ tool listings: lumiworx.com/essays/2016/12/yashica-ml-28-85mm-cleanupLuckily the ML 50mm f/1.4 was well engineered and dismantling it is pretty straight forward. The entire front barrel can be unscrewed (counterclockwise) and it exposes the notched ring holding in the front element group, and it will slide out as one single assembly. The spanner needs the flat bladed tips installed to slide into the two slits in that inner ring, and it too, unscrews counterclockwise. Once the front optical block is removed you'll see a single slotted screw that fixes the blade holding ring in place, and when the screw is removed, the ring can be twisted slightly to get the tiny tabs that stick out of its edge to clear the slots in the 'shelf' of the inner barrel that holds in it place. A word of caution, and I can't stress it enough... work slow, and mark EVERYTHING you move or remove with a scratch on the 2 mating pieces so you can line them back up when reassembling the lens after the fix is complete (i.e., inner barrel and holding ring). it can be mounted wrong and bind on the blade pivot posts if in the wrong place. ALWAYS assume that something can fall out and will bounce out of sight, so use a cloth or soft mat to work over. And... latex/nitrile gloves are lifesavers and keep finger oil away from glass elements that I'll guarantee you'll accidently touch and smudge at least once while opening or closing things up. Before even attempting to clean the oil, the tension relief from that holding screw being removed will likely be enough to get the blades to start moving again, but they'll probably be mighty slow to move and/or not open all the way. There are two ways to clean the aperture blades. One is the traditional way that requires more or less a complete removal of the whole iris assembly, and the way most YouTube videos are likely to show it being done. I've done it enough times that I don't remove the blades unless they are absolutely saturated by a previous owner who treated everything movable like it was his/her lawn mower wheels that were lubed with a spray can of WD40. I dip a paper-sticked cotton swab into 99% isopropyl alcohol, and very very gently wipe down the blade faces in various stages of being half and fully closed down. When the alcohol evaporates, the oil is wicked into the cotton, and I change swabs as many times as needed until there's no more oil streaks showing on the blades when adjusting the aperture. The blades can't hold up to pressure at all, so it takes a considerable amount of time with a light touch to wipe them down. Once I'm satisfied they're clean enough, I will never put any oil on them again. Whatever was sitting there has penetrated enough to make it unnecessary to add any more. It's the wee hours at the moment, but later on I'll take a few shots of an open lens for annotating the details of what it all looks like inside once I've had a chance to set things up.
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on Aug 23, 2022 18:48:58 GMT
Last Edit: Aug 23, 2022 18:51:54 GMT by lumiworx
Hopefully the photos are clear enough that arrows or colored boxes aren't needed to see what's where, so maybe just descriptions will suffice. 1. The front outer barrel and surround ring is removed to expose the front element group, and shows the spanner loaded with the straight blade tipped pins. 2. Top view of the lens, shows the two slots on opposite sides of the 'ring' surrounding the top of the group (extreme screen left and right). This isn't really an actual ring in this case, as it's just shaped like a seperate ring, but it's actually machined out of the whole group cover piece. 3. Top-down view of the exposed iris assembly, with the entire front element group flipped upside down to its left. 4. A closeup of the blade retaining ring and its lone lock screw. The ring is like a flat washer that has cutouts in it, and has tiny fingers/tabs that slide under the small lip attached to the inner barrel. To the immediate right of the screw is one of the slots those tabs get set into, and the whole ring is twisted a few degrees to slide the tabs under that lip, or out from under them to access the blades. I always treat them like lens mount bayonets, and assume they are indexed to a certain position, which is why I will mark their installed location with a set of scratch marks, and do the same to mark the slot where the lock screw is meant to get threaded into, so it doesn't end up in the wrong hole. I didn't remove the ring to photograph the blades themselves, but they have a set of extremely short pins running through each of them... one is the pivot point, and the other one slides along a guide path cut/punched into another ring underneath the blades. That ring gets attached to the actuator that adjusts the aperture by using that 2nd pin to offset the angle of the blades when that lower ring is rotated. One important note on how the blades are set up... they overlap each other, and if removed, you'll have to recreate that 'weaving' of the blades, so do study how that works if blade removal is on the agenda to get everything clean. One last caveat on the lock screw. It should not be tightened to it's limit. Slightly snugged is more than sufficient. Too tight and it will likely clamp down on the blades, and also deform the lock ring enough that it will not only bind things up, but will need to be replaced outright because of extremely fine tolerances on clearance. I doubt anyone could get one truly flat again after being bent. Opening this ML 50mm f/1.4 has reminded me that it needs to have it's front group receiving threads degreased, as well as those on the mating outer threads of the element block itself. Too much grease and it can off-gas particles and haze up glass, and this one -although it hasn't needed blade cleaning - suffers from too much thread gunk.
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on Aug 25, 2022 3:28:51 GMT
Posted: Aug 25, 2022 3:28:51 GMT
Thanks for the pictures, instructions and tips Lumiworx. I'm still processing the information in your post. I will ask if I have any questions. Looks like this is a weekend job. I need to order the tools first.
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on Aug 25, 2022 13:51:04 GMT
Last Edit: Aug 25, 2022 14:10:39 GMT by lumiworx
You're welcome m43yash . Since the steps to remove and return the front block are few and can be done quickly, it's easy and simple to do and redo those steps as many times as needed until things are back in operation. Replacing the front block - even partially - keeps out dust and bugs/particles/hairs/etc., while you go through multiple cleaning sessions. One thing I didn't mention on using swabs... use as many of them as it takes, and don't reuse the same one. Every time the alcohol evaporates and the swab has collected oil, flip it end over end to use the 2nd tip, and dispose of it once that one's been used. There's no point in trying to reuse an already oil soaked swab, since it's unlikely to keep on absorbing wicked-up oil after one pass. That's not as big of an issue if you remove the blades entirely and give them a soak in a dish filled with alcohol, but the same will apply when wiping down the oily internal parts of the rest of the assembly.
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on Aug 30, 2022 4:33:44 GMT
Posted: Aug 30, 2022 4:33:44 GMT
Hello Lumiworx,
I removed the ring (step 1) and noticed that the slots on the front element group (step 2) is not present in my copy. Do you know if I have to use some other method to remove the front element group? Thank you, as always!
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on Aug 30, 2022 14:47:58 GMT
Last Edit: Aug 30, 2022 14:57:59 GMT by lumiworx
My first thought was that someone may have swapped out the barrel and ring on some other brand of lens, but I figured it might be a reasonable idea to check before directly inserting foot into mouth. I have multiple ML 50mm 1.4's and of the 6 that I have easy access to, one of them seems a match to yours. These all fall into 4 serial number ranges - All starting with "A" - under numbers starting with 102, 103, 106, and 108. My serial number list shows I have additional versions under 107 and 109 as well as others in the 102/103/106/108 runs.
I made some notations on several of the others (currently packed away) about which of them I'd done some cleaning (either blades or just haze/etc.) and none of the 107/108/109 versions were touched, so there may have been a fundamental change in construction on the later year runs, but I don't have any idea where that happened in the timeline, or how consistent those changes are over time, and whether any/all subsequent years may have this same, and changed, mechanical design. The only thing I can say with any certainty, is that any I've done teardowns and cleanings on are in the 102/103/106 ranges... and they all have the dual slit 'ring' feature.
I'll have to investigate the one copy I have in-hand - a 108 version - and see what I can find on how it comes apart.
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on Aug 30, 2022 17:23:45 GMT
Posted: Aug 30, 2022 17:23:45 GMT
Hello Lumiworx, My lens serial number starts with A106. Just thought I'll let you know.
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on Aug 31, 2022 19:10:29 GMT
Last Edit: Aug 31, 2022 19:20:58 GMT by lumiworx
Alrighty. I have the solution, but it might mean being creative in how you get the front group out, or optionally, adding something new to the toolset. The same parts seem to be used in both types of assemblies, and they come apart the same way, however... the difference is the absence of the slots that allow the use of a spanner for leverage to get them unscrewed. Essentially something has to grip onto the inner 46mm diameter 'ring' piece at the front of the assembly. The slotted version is the same size and shape as the non-slotted one, so everything still looks the same as in the pics above as reference. Among my other tools is a set of rubber lens cups that are used to press onto the face of lens rings to unscrew them when that's the method used as the first part of disassembly. The 2nd largest of that set - at the wide end of the cone shape - is 44mm in diameter, and will stay well seated to use it as a grip/handle/etc to unscrew the element group. I won't say they would be necessary in this instance, but they will work for anyone else following this thread, to remove the front group if you already have a similar set. An alternative would be to turn the lens face down on a rubber sheet or ring, and after applying some pressure, turn the entire lens counter clockwise. There are a couple of things of note to do it this way, and it will be dependant on what materials you'd have on hand for the task. First and foremost, there is a very very slim amount of space between the glass face of the front element, and the 'plane' of the front edge of the rim. I'd estimate it's less than .25mm. If the grip surface used can compress enough, it could easily lead to damaging the glass while twisting, so I'd suggest cutting a 40mm hole into whatever is used and have the material be of significant thickness that the glass never touches anything while unscrewing it. Think in terms of a donut or rather large grippy washer. I've used this technique many times to get off very stubborn filters, so it does work as an outside the box way of getting this kind of job done. There's a caveat on how the unscrewing action works too. Rotate the focus to the close distance end of travel until the front section of the barrel is fully extended when removing the front barrel/ring group. Turn the aperture ring to f/16, and when twisting to unscrew the lens grouping, only hold onto the rear barrel and aperture ring while you turn. Otherwise the focus grip turns in reverse while twisting and will pull the inner barrel back into the lens and it loses contact with the grip surface. I'm astonished that there is such a fundamental difference in construction on these particular lenses, and how this one small change was acceptable to what was already in use. If it was for cost cutting only, I can't imagine the savings would have been enough to justify the elimination of the slits and the complications it may have caused in ease of repair. These aren't exactly assemblies you want to trust being 'good enough' when left secured at only finger-tightness. [ BTW... I get no commision on any of these, so I'm not plugging tools to get rich from referrals. :) ]
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on Sept 7, 2022 1:20:53 GMT
Posted: Sept 7, 2022 1:20:53 GMT
Hello Lumiworx,
I kind of succeeded and failed in freeing the aperture blades.
I removed the front element using resistance exercise band as a friction enhancer. The aperture blades were indeed stuck. I applied 91% Isopropyl alcohol to the top of the plate that holds the aperture down. That plate was loose, and with the application of the Isopropyl alcohol, the blades loosened and closed down to f16.
However, when I tried to open the aperture and close down, the blades did not close down.They open and stay there until I applied Isopropyl alcohol again. I tried three times, and I stopped.
Jiggling the top plate vigorously causes the blades to close, but once retracted, they stay open. Not sure what I need to do to fix this. Do I loosen the single screw that is holding down to free up the blades a bit? Or Are the blades with insufficient lubrication?
Any guidance will greatly help.
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on Sept 7, 2022 15:10:50 GMT
Posted: Sept 7, 2022 15:10:50 GMT
It's good to hear you were able to remove the front element, so you'd get access to the blades. The positioning and size/shape of the black ring that covers the hinge pins of the blades will prevent you from ever getting everything clean enough for the aperture to function once the blades are stuck as badly as they seem to be. Any excess oil will cling to the underside of that flat ring and without removing it for a thorough soaking, the blades will never perform as intended. Soaking the ring in alcohol for the amount of time it takes to clean the blades should be sufficient, with a good wipe down with a clean lint-free pad or cloth afterwards to keep it oil free. Removing the ring will likely bring half of the excess oil along with it, and without removal, it's unlikely that swab cleaning alone would provide enough capillary action to remove enough oil trapped under it, to free everything up. You're at the point you'll need to take a leap of faith. As mentioned before... take a straight pin, needle, scratch awl, or similar, to scratch some matching lines on the inner barrel and locking ring before removing the ring. Here's the idea to use as a reference - in practice, in a video on cleaning a Zeiss 50mm Planar - starting at the 5:59 timing mark, to see what I mean: youtu.be/GQot-U3YPio?t=359The rest of the video won't help with getting access to an ML 50mm f/1.4 aperture or a complete lens reassembly, but at the 9:40 mark, it does show the complete removal of all the blades for cleaning and the aperture's reassembly if you'd prefer to go that route. Not exactly the exact same procedure as a wipedown, but it will give an idea of the full process. Since you've determined that there was excess oil causing the problem, I would never, ever add another molecule of oil after swab cleaning. The metal has absorbed enough for decades more of lubricated service without reintroducing the cause of its current issue to flare up in the future - as long as you don't strip it bare and soak every single part of the assembly under the blades if you remove them to soak... just a surface wipe on the exposed under-ring with a swab dipped in alcohol should do nicely. That should leave a tiny bit of oil residue at the pivot points.
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on Sept 11, 2022 18:35:55 GMT
Posted: Sept 11, 2022 18:35:55 GMT
Hello Lumiworx,
Good News! I left the lens undisturbed for few days,and it looks like the aperture blades eventually freed up on their own. I could close the aperture to f16 and open all the way with no issues. Shots at f2 and above are crisp! This is one nice lens (other one is ML 50 f2) that makes want to me want to shoot mundane objects just to see the warm colors and clear pictures, especially taken after the sun sets!
HOWEVER, I think some of the isopropyl alcohol with oil residue spilled on the inner glass element. Wide open, I see more blue fringing when the background is bright which I did not see before. Is it because of (presumed) oil residue or the front element may not be screwed tight? Or am I imagining? What would be a good lens cleaner that does not leave residue? I tried rubbing alcohol pads that is used for medical applications and it does not seem to make a difference.
Thanks for your help! If not for your instructions, I would have not fixed this lens. I was planning to shoot wide open for ever!
Oh BTW, the ML 80-200 f4 that I got as a package deal is also wonderful, if I accept purple fringing when shooting against bright background. Most of the times, it performs better than my 40-150 f4-f5.6 Oly kit lens at all comparable zoom distances. Some say it is really a re-badged Tokina 80-200 f4, but I don't care. I don't know how to post pictures in the forum, got some pictures.
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