Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
07-10-2016, 12:05 AM   #1
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
PLEASE HELP: Assembly problems with SMC Pentax 50mm F1.2

Hey Pentaxians,

I bought a cheap (? 250! ) 50mm F1.2, unfortunately with a lot of fungus inside.
No Problem for me, I thought. I often dissambled and assembled manual pentax lenses but never had this problem:
I never put out the lens barrel. So now I have to re-calibrate and adjust the lens.
Never did this before and I tried so many positions but not get it beack to basic settings.
I thought measuring the distance from top to back would be alright. Otherwise I used a white marker to mark the transitions - i forgot it. I forgot to make fotos too .

BUT: the lenses are free of fungus now .

Can someone please help to assemble the lens? Some tips and tricks? are there special positions of tubus/lens barrel too look for.

Pictures would help a lot, if possible.

If I will get it back to genuine settings, I will Dissamble the whole lens again and make fotos of the complete Dissamble/Assemble for all Users and the Dissambly Data Base.
So every tip and trick you will give is a great help for everyone.

If someone will not give these information to everyone, please write me a PM. If you not want to have published your knowledge let me know also, and I will conceal the information to adjust in the Dissambly Data Base.

Great Thanks to all Answers,

Milka

Attached Images
View Picture EXIF
COOLPIX P500  Photo 
07-10-2016, 12:27 AM   #2
Site Supporter




Join Date: Jul 2012
Photos: Gallery | Albums
Posts: 3,593
Have you tried fishing around on Youtube? There are many great videos showing how to repair many types of photographic equipment. Hope this helps.

Antonio
07-10-2016, 02:14 AM   #3
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
Not for the 50mm F1.2
07-10-2016, 08:17 AM   #4
Site Supporter




Join Date: Jan 2011
Posts: 2,296
dcshooter may help. send him a message

07-10-2016, 08:23 AM   #5
Site Supporter




Join Date: Mar 2014
Photos: Gallery
Posts: 960
did you take apart the helicoil?
07-10-2016, 08:31 AM   #6
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,105
If by original settings you mean infinity focus then you either need a collimator or focus on a distant object. Adjusting the infinity focus should be pretty much the same as with other lenses of the same focal length in the model series (e.g. SMC 50mm f1.4). Depending on the design of the lens this is done with the outer barrel focusing ring removed. Once set, slip the focusing ring on - align the infinity mark with the focus indicator mark and tighten the screws that anchor the ring to the barrel of the helicoid mechanism. Some lenses you can't get at the helicoid barrel to turn it so you have loosen and tighten the anchors to turn the helicoid barrel beyond the stops on the focus ring.

Provided you reassembled the helical barrels in a position where the travel is enough for infinity and close focus. If not you have to reassemble this at the proper entry points.

There is a thread on how to DIY collimate using a film SLR body. Or just use a distant object that is focused at infinity on a same focal length lens.
07-11-2016, 12:06 PM   #7
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
more detail

For a better communication lets please use the following numbers of the picture for the description, or give me the name of the parts please. I did never heard the words holicoid or barrel. sorry =(
Attached Images
View Picture EXIF
COOLPIX P500  Photo 
07-11-2016, 12:31 PM   #8
Moderator PEG Judges
Kerrowdown's Avatar

Join Date: Aug 2008
Location: Highlands of Scotland.
Photos: Gallery
Posts: 31,801
What number is the wee man in the top left.

Looking at all these bits, is why I'd put mine in somewhere if anything needs done.

07-11-2016, 01:11 PM   #9
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,105
Part #2 should break down into two major components:
a. outer focus ring (where the textured grip goes)
b. the outer barrel of the helicoid. You can see the silver helicoid threads

The outer ring should be held in place by 3 screws. Remove these 3 screws and the focus ring should slip. Reassemble the two barrels of the helicoid. Reassemble the rest of the lens except for the focus ring (call it 2b). Mount the lens on a camera body, adjust the focus on a distant object that focuses at infinity. Slip 2b onto the barrel - align the marks to infinity. Replace the screws. Check infinity focus as well as minimum focus. Loosen screws and adjust as necessary.

If you can't get infinity or minimum focus it is because you didn't start the helicoid at the correct entry point. Disassemble the helicoid and try again. If you didn't make markings to help you find the correct entry point it is just a matter of trial and error.

Since you have the helcoid apart you may as well clean it and re-grease the threads. It should be possible to clean all the lens elements without taking the helicoid apart.

In this thread on disassembling the 50mm f1.2 lens the third to last and following pictures show the removal of the focus ring. The last photo shows the helicoid assembly without the focus ring.
https://www.pentaxforums.com/forums/114-maintenance-repair-articles/278469-pe...mbly-pics.html

Although this is for the 28mm f3.5 the basic design is the same lacking some of the extra rings and screws. See photo 5 in the sequence on which screws hold the focus ring.
https://www.pentaxforums.com/forums/54-pentax-lens-articles/179912-pentax-k-2...-cleaning.html
07-11-2016, 02:04 PM   #10
Pentaxian
Audi 5 cyl's Avatar

Join Date: Mar 2015
Location: France
Photos: Gallery | Albums
Posts: 344
You have 8 different positions to start screwing part 1 into part 2. Screw it in, assemble, test. If it does not work, disassemble, screw it in, assemble and test. If you are lucky, hit and miss will give you results relatively fast. And that is pretty much what I would advise you to do.
Alternative is to look around the web for a picture of the lens at infinity and estimate the length of the part 1 that is visible in the front when screwed into the part 2 and then test trying to achieve that without a complete assembly.

Hope it works for you. If not, I'll be happy to liberate you of your tortures at a buying price

Regards,
Marko
07-13-2016, 01:49 PM   #11
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
Assembling the lens - Part I

Hey,
here is a step by step assembling of the 50mm F1.2 lens. I did not know where the failure is but at the end I did get near infinity but no close focus at 0.45m, just up to 0.6m (see pics).
The last pictures are taken with K3 at infinity (F1.2 - F2 - F2.8 - F4) and at close focus (F1.2 - F2 - F2.8)
Attached Images
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
07-13-2016, 01:52 PM   #12
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
Assembly the lens - Part II

here is part II
Attached Images
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
07-13-2016, 01:54 PM   #13
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
Assembling the lens - Part II

here is Part III
Attached Images
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
View Picture EXIF
COOLPIX P500  Photo 
07-13-2016, 02:00 PM   #14
Forum Member
MilkaSchokoHase87's Avatar

Join Date: Sep 2015
Posts: 63
Original Poster
some example - photos

here are some examples taken at infinity and maximum close focus (between 0.55 and 0.6m). on K-3.

close focus @ F1.2 / F2 / F2.8
infinity @ 2 / F2.8/ F4

Hope you can find the error in my Assembling to solve the problem. Great thanks for all your answers.
Attached Images
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
View Picture EXIF
PENTAX K-3  Photo 
07-13-2016, 03:03 PM   #15
Site Supporter




Join Date: Mar 2014
Photos: Gallery
Posts: 960
congrats nice job, and rewarding too.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
50mm, assambling, assemble, base, data, dissamble, dissambling, f1.2, focus, fotos, help, information, lens, lot, pentax k, pentax service, positions, repair, service, settings, warranty
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Help : problem with the SMC Takumar 50mm f1.4 redcat Pentax SLR Lens Discussion 11 06-09-2015 12:33 AM
Pentax M 50mm f1.7 Disassembly - Assembly jaitas Pentax SLR Lens Discussion 8 08-22-2014 09:16 PM
50mm f1.2 smc M lens with dslr help rozzercass Troubleshooting and Beginner Help 3 03-01-2013 11:26 AM
HELP - F-- Error (Blinking) with new SMC Pentax-M 50mm F1.7 IanAntonio Pentax K-5 6 10-18-2012 01:39 PM
Need help with exposure problems and snow photography problems, urgent please respond montezuma Photographic Technique 7 02-24-2008 05:43 PM



All times are GMT -7. The time now is 03:47 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top