[Dean Bradshaw]

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Hi everyone
I've just received a PK mount Kiron Kino Precision 28mm f2.0 in generally very good condition. Body is mostly unblemished and glass looks great...some fairly minor dust, but no nicks, scratches or fungus at all.
However...the aperture ring does nothing! The aperture will not stop down and operating the aperture lever doesn't change the situation.
There is also a noticeable rattle, so no doubt some things has worked lose.
Anyone had much experience with this or similar lenses? any thoughts on how to access the aperture blades? I've accessed the lens from the rear through the mount, which hasn't revealed the issue...but i haven't removed any elements yet, so haven't actual seen the aperture mechanism itself.
Just looking for any suggestions or tips before I dig deeper...and potentially bugger something up in the process
Cheers
Dean

[Barabas]

I've repaired three of these lenses, they all have the same problem after a while; sticky aperture blades. The best thing to do is to change the grease of the helicoid, since it is the grease from there that gets in between the aperture blades. You can also only clean the aperture blades but then they will need to be cleaned after a while again.

To access the blades is quite easy; the rear elements can be taken off in one part, and then you can see the blades. You can then clean with a cotton stick and some alcohol, or lighter fluid. It is also possible to take out the blades and the ring that holds them but be carefull, the blades are very light and thin.

The rattle you hear is normal, all my copies had it. So there is nothing very wrong with your lens, it just needs maintenance. Since all Kiron 28mm lenses will have this problem sooner or later, I do consider it to be a mistake in design... the Komine made Vivitar 28mm f2.0 close focusing doesn't have the problem and is a good alternative, but it's not a Kiron ;-)

Here's some pictures on how to open the lens:
https://www.flickr.com/photos/paulojgomes/2988406977/in/photostream/

[ramseybuckeye]

I've read in a few places that this is common with that particular lens, but it is worth fixing in my opinion. I had a copy of it and it was the sharpest lens I've owned. I sold it to make money for another lens and kicked myself shortly after that. But mine did not have the A setting and maybe I will find another someday.

[Dean Bradshaw]

I am actually in the process of cleaning an aperture mechanism on one of these for another forum member and will be posting pics in a few days if you don't mind waiting.

Thanks dcshooter.
Well, that's a lucky coincidence for me
I'll look forward to your photos when you have a chance to post them.
TBH I was hoping you'd look in on this thread, so thanks again.
Cheers
Dean

---------- Post added 12-19-15 at 11:16 PM ----------

I've repaired three of these lenses, they all have the same problem after a while; sticky aperture blades. The best thing to do is to change the grease of the helicoid, since it is the grease from there that gets in between the aperture blades. You can also only clean the aperture blades but then they will need to be cleaned after a while again.

To access the blades is quite easy; the rear elements can be taken off in one part, and then you can see the blades. You can then clean with a cotton stick and some alcohol, or lighter fluid. It is also possible to take out the blades and the ring that holds them but be carefull, the blades are very light and thin.

The rattle you hear is normal, all my copies had it. So there is nothing very wrong with your lens, it just needs maintenance. Since all Kiron 28mm lenses will have this problem sooner or later, I do consider it to be a mistake in design... the Komine made Vivitar 28mm f2.0 close focusing doesn't have the problem and is a good alternative, but it's not a Kiron ;-)

Here's some pictures on how to open the lens:
https://www.flickr.com/photos/paulojgomes/2988406977/in/photostream/

Hi Barabas and thanks for your post. Sounds like there is good hope the lens will live again
I think I had seen online that this lens had frequent issues with stuck aperture blades, but the rattle threw me off...really sounds not quite right...so glad to hear that is not an issue.
I've had a quick look (it's 23:15pm in Perth, so no working on lenses right now for me) at your pictures of the disassembly. I notice my version looks different to this. Mine is a PK mount and has 3 black screws on the black part of the rear of the lens, but 5 silver screws holding the mount on itself. It looks like you're version has just 3?
As said, I haven't gone any deeper than this yet, so I'm sure your pictures will still be very helpful. Hopefully I'll still have some time in 2015 to have a closer look at this lens.
Cheers
Dean

---------- Post added 12-19-15 at 11:19 PM ----------

I've read in a few places that this is common with that particular lens, but it is worth fixing in my opinion. I had a copy of it and it was the sharpest lens I've owned. I sold it to make money for another lens and kicked myself shortly after that. But mine did not have the A setting and maybe I will find another someday.

Thanks for your post ramseybuckeye.
Apart from this issue the lens is in really pretty nice condition. Doesn't seem to be heaps of info online about this lens, but enough to make me think it was worth a shot...if I can get it working
Mine is also lacking the A setting, just standard PK mount.
Cheers
Dean

[elementdtlop]

the 28 2.8 had this problem too from what I've read. i went with a komine 28 2.8 to avoid the issue and its amazing how sharp it is. i have heard the kiron lenses were just a tad sharper though so if you can fix it you have a good lens esp since you have a 2.0.

[Dean Bradshaw]

the 28 2.8 had this problem too from what I've read. i went with a komine 28 2.8 to avoid the issue and its amazing how sharp it is. i have heard the kiron lenses were just a tad sharper though so if you can fix it you have a good lens esp since you have a 2.0.

Thanks elementdtlop.
Yeah, I'm hoping so
It's got a bit of vintage softness and glow at 2.0, but looks good...hoping to be able to see how it performs stopped down
Cheers
Dean

[Not a Number]

The grease Kino/Kiron used is a common source of problems - outgassing and creep/bleeding. It was considered hi-tech at the time.

[Arjay Bee]

There is a club thread for Kiron lenses. There are a few images in that thread taken with the 28mm f2 lens including mine - now sold on due to lack of use and to fund some ltd lenses.

https://www.pentaxforums.com/forums/122-lens-clubs/251683-kiron-lens-club.html

Sounds like you will get yours back in full operation... look forward to seeing some WA example images.

[osv]

I think I had seen online that this lens had frequent issues with stuck aperture blades, but the rattle threw me off...really sounds not quite right...so glad to hear that is not an issue.
I've had a quick look (it's 23:15pm in Perth, so no working on lenses right now for me) at your pictures of the disassembly. I notice my version looks different to this. Mine is a PK mount and has 3 black screws on the black part of the rear of the lens, but 5 silver screws holding the mount on itself. It looks like you're version has just 3?
As said, I haven't gone any deeper than this yet, so I'm sure your pictures will still be very helpful. Hopefully I'll still have some time in 2015 to have a closer look at this lens.

i have/had three copies of this lens, none had sticky aperture problems, but one of 'em does have haze inside the rear lens group.

mine are vivitar 28/2 lenses, 22xxxxxx serial, 3/5 screw configuration, not like the nikon-mount lens in the pics.

however, the rear lens group does indeed unscrew all as one unit... remove the three screws in the black mount, and you can just fit a lens spanner wrench onto the top ring.

the entire group should unscrew, but i suppose that there is a chance that only the top ring on the group will loosen.

it's pretty straightforward, but of course you'll need the spanner wrench and preferably some jic screwdrivers.

i tested this glass for field curvature in landscape photos, on the a7r, if you want to see what it looks like stopped down:

28mm camera lens comparison, on the Sony a7R: first round

on ff, this lens changes radically from f/2 to f/10, it's like night and day; rather weak wide open, but as you can see above, it's respectable at f/10... just a hint of a wavy focus field, so it's not quite a match for the pentax-m 28/3.5, but then most lenses aren't... here it is at f/2.8, in about the worst possible lighting conditions, shot with the Sony a7R, iso10000, Vivitar 28/2.0 at f/2.8, ambient lighting only, no flash.

[elementdtlop]

28mm camera lens comparison, on the Sony a7R: first round

on ff, this lens changes radically from f/2 to f/10, it's like night and day; rather weak wide open, but as you can see above, it's respectable at f/10... just a hint of a wavy focus field, so it's not quite a match for the pentax-m 28/3.5, but then most lenses aren't... here it is at f/2.8, in about the worst possible lighting conditions, shot with the Sony a7R, iso10000, Vivitar 28/2.0 at f/2.8, ambient lighting only, no flash.

really really awesome picture. iso 1000 or 10000? it doesnt look like there is any noise at all.

[osv]

thanks, it was iso10,000, 1/1000th shutter speed, and i think that i was trying to pan the car because of the slow shutter... the track photog wouldn't let me use the flash anymore, so i had to wing it... no lens hood, light was coming in the front of the glass from the light on the pole, and also bouncing off of the white k-wall from underneath, into the front of the lens... it's the only time that i've ever seen that sensor(?) reflection artifacting with the a7r, so watch out for it with this lens on pentax cameras, under radical lighting conditions... it was happening on every shot.

i cleaned it up with dxo prime, but it never had that red grain noise look to it, like what's in this example... it was just a low rez photo, because of the clean grain artifacting. Noise Ninja 2.0Can Software Cure High ISO Digital Files? Page 2 | Shutterbug

the new pentax ff camera will probably give similar results.

[Dean Bradshaw]

Thanks everyone for the further input.
I haven't had a chance to look further at the lens as yet, but hopefully I'll have a chance in the next few days to see how I go with getting at the aperture mechanism.
I'll update when I have the chance...and thanks again everyone.
Cheers
Dean

[Dean Bradshaw]

Little update.
I had some time yesterday and managed to get into the lens...even managed to not lose the tiny aperture ball bearing or little grub screws
Yep, oily and greasy inside. I have manually cleaned out a good amount of the grease on the helicoid, not using any solvents as yet. Wide down all surfaces, such as the barrel exposed by removing the aperture ring.
I have spent anytime on the glass itself, though the elements behind the aperture look like they need some attention. With the amount of oil on the blades no surprise that the glass has probably got a film too.
I'm not brave enough to remove the aperture mechanism itself, so I've just used isopropyl alcohol on a cotton bud to try and clean off as much oil as possible...but I can only access one face of the aperture. This has at least freed up the blades and they are now at least moving and stopping down.
I re-assembled the lens, to avoid losing any parts, but it's far from pristine just yet. In the re-assembly I've created an issue where the aperture ring won't turn once I have the mount back in place, but is fine with the mount off...hopefully I'll be able to figure that out when I next disassemble.
Does anyone have any suggestions for the most appropriate solvent to use on the helicoid grease?
Also, best lubricant to use on the helicoid after cleaning old grease?
Thanks
Dean

---------- Post added 12-23-15 at 06:12 AM ----------

About half of the copies of this lens are easy to disassemble and half have so much glue applied to the threads that it is nearly impossible to get the lens groups out. Oddly, the Vivitar version has access holes through which you can put in solvent with an eyedropper to soften the glue, but the Kiron version does not.

One other thing to check while you have it apart is that the elements don't have oil on them as well, which often happens as well.

Hi dcshooter
Thankfully all of the screws were relatively easily removed. I have a set of JIS drivers which no doubt helps. It does look like at least the rear element has some oil on internal face...but I'm a bit nervy about removing the aperture mechanism itself to better access that glass...we'll see how I go
Cheers
Dean

---------- Post added 12-23-15 at 06:22 AM ----------

I've repaired three of these lenses...

Here's some pictures on how to open the lens:
https://www.flickr.com/photos/paulojgomes/2988406977/in/photostream/

Thanks Barabas
Your Flickr link helped quite a bit. I've taken apart a few Taks before, so the different construction of the Kiron had me guessing a bit.
Cheers
Dean

[niceshot]

Yes check to see if you didn't roll over one of the electric contacts,as this happened to me.Drove me nut till I figured it out. Good luck

[Not a Number]

Also, best lubricant to use on the helicoid after cleaning old grease?

I've been using this product and am quite pleased with the results. Other forum members have used the same product and seem satisfied also. This vendor ships worldwide but you may be able to find a more local source:

Helimax XP Camera Telescope Optical Instrument Focusing Helicoid Grease w PTFE | eBay