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Forum: Pentax SLR Lens Discussion
11-02-2020, 09:21 PM
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Forum: Pentax SLR Lens Discussion
11-02-2020, 09:06 PM
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It's not going well. I bought an appropriately-sized filter wrench to provide increased grip and leverage. Even though it's rubber-clad, it slipped on the very smooth branding ring when i squeezed hard and turned. Then i tried wrapping the ring in double-sided tape to prevent slippage. It did do that quite well, but i still could not get the ring off despite applying as much torque as i could muster. This sucker is screwed on really tight. I also tried dripping acetone into the gap to soften any thread-lock: no dice. Same for applying heat with a hair dryer.
I'm just about resigned to living with the stiff focus action.
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Forum: Pentax SLR Lens Discussion
10-31-2020, 11:02 PM
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Thanks, Steve. I had already read that thread and not found in it any help for removing the branding ring (on which the lens name is actually engraved, not the nameless "name ring" mentioned in the thread). However, you did just now remind me to try and contact the last commenter in the thread, "lucca1x", who, judging from the pictures he posted, must have succeeded in removing the branding ring.
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Forum: Pentax SLR Lens Discussion
10-31-2020, 10:17 PM
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Even before reading your reply, i saw those three tiny set screws just afore the distance scale and suspected they were for calibrating the scale. I'll try to confirm this later.
---------- Post added Oct 31st, 2020 at 10:36 PM ----------
Sadly, my only screwdriver that fits these tiniest of set screws was unequal to the task. When I applied enough torque to loosen the screws, the driver's shaft started spinning freely, unmoored from the handle. Time to buy a new screwdriver.
Thanks for the link! I'll give them a try.
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Forum: Pentax SLR Lens Discussion
10-31-2020, 12:41 AM
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Well, I guess I won't be doing that again.
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Forum: Pentax SLR Lens Discussion
10-30-2020, 09:26 PM
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Forum: Pentax SLR Lens Discussion
10-30-2020, 06:19 PM
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Well, I'm back to the advice trough for more help with this lovely lens. Having cleaned a hazy element last time with help from this forum, my new goal is to redo the lubrication of the focus helicoids. The focus action on my copy is smooth and very well-damped, but stiffer than I like. I did read somewhere or other that Kiron may have intentionally tuned the lubrication on this lens to be rather stiff straight from the factory for the sake of maintaining focus once it's set... but who knows if that's a reliable report? I wonder if anyone reading this is/was an original owner of this lens, and if they remember the focus action always being stiffer than is typical for a manual-focus macro lens....
Anyway, my difficulty is that I can't figure out how to separate the helicoids. I need to do that in order to clean the old grease off and put new grease on in an appropriately small amount. I have tried softening the old grease with a bit of lighter fluid, but that didn't change the resistance.
The outer helicoid keys were easily removed. But that didn't let me unscrew the inner barrel from the outer. I think I need to remove the name ring at the front of the outer barrel, which seems to act like a retaining ring for the inner barrel. However, I can't figure out how to remove this ring! I thought I could just twist it off. There is a screw just aft of the ring that seems like it might be involved in keeping the ring in place, but removing this screw didn't make it any easier to twist the ring off. I also applied acetone to the tiny gap between the name ring and the outer barrel, to no avail.
Has anyone taken this lens apart? Thanks is forthcoming.
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Forum: Troubleshooting and Beginner Help
10-10-2020, 11:40 PM
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Beautiful photo!
That's good to know for next time.
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Forum: Troubleshooting and Beginner Help
10-10-2020, 11:15 PM
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Mission accomplished. God, it was so easy. The key was found in these very forums:
Vivitar 100mm 2.8 need fixing.... - PentaxForums.com
After removing the aperture ring and the one adjacent to it, the rear element assembly was trivial to remove by manual unscrewing. Luckily, I was right about the location of the haze: it was on the element closest to the aperture diaphragm—and on the outer surface at that. Very easy to clean off, and there were in fact no scratches. The arcs seen in my photos must have been cleaning marks from a previous attempt. They wiped away along with the haze. The glass is now as clean as I could wish.
The cleaning has had no visible effect on image quality. As I had suspected, the haze was too thin to have any effect in the first place. But now I won't have to mention any haze if/when I decide to sell this lens on to the next curious george.
---------- Post added 10-10-20 at 11:18 PM ----------
Thanks for that!
---------- Post added 10-10-20 at 11:19 PM ----------
That's hilarious. And nice photo!
---------- Post added 10-10-20 at 11:24 PM ----------
I did notice those slots, and right though you may be, I feared that using a spanner on that retaining ring would do nothing more than loosen the rearmost element. That's why I wanted to remove the mount and aperture ring to expose the whole rear element assembly, because I suspected that it would just twist off by hand.
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Forum: Troubleshooting and Beginner Help
10-10-2020, 10:30 PM
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If someone can teach me the trick to removing the aperture ring on this lens, I think I can manage the rest on my own (as far as accessing the affected element goes). There is something preventing me from simply lifting the ring off, and it's not obvious what it is.
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Forum: Troubleshooting and Beginner Help
10-10-2020, 09:35 PM
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The scratches are actually not severe, and I'm not even convinced they are scratches. Like the haze, the circular marks are invisible without a flashlight. (These pictures make everything look a hundred times worse than it really is.) They do not appear to have any effect on images.
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Forum: Troubleshooting and Beginner Help
10-10-2020, 09:13 PM
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I just purchased the Vivitar 100mm f/2.8 version of this "legendary" lens. Upon close inspection of the glass, it turns out there is light haze on an interior element toward the rear. In the attached photos, the haze looks much worse than it does under ordinary circumstances. This haze appears to consist of thousands of tiny dots, which I speculate are oil droplets, either deposited by sputtering from the aperture blades or condensed from evaporated lubricant.
I would like to access the affected element to clean the haze off, but I'm stuck. My best guess is that the element is between the aperture diaphragm and the rearmost element. How do I get to it? So far, I have successfully removed the bayonet mount, but I could not figure out how to remove the aperture ring.
Hints, anyone? Thanks.
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Forum: Welcomes and Introductions
12-18-2017, 06:21 PM
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Thank you 😉. My first real camera was a Pentax K1000, so I have a certain fondness for the brand. Also owned an MX and, ultimately, an LX before switching to Nikon — and that only because my dad gave me his F3. If he hadn't, I'd probably still be with Pentax to this day.
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Forum: Welcomes and Introductions
12-18-2017, 01:08 PM
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Hi, everyone. I'm actually a Nikon user, but I've found these forums to be one of the very best resources on the internet for researching old lenses. Thank you all for keeping up a great treasure trove of information.
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