Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
08-16-2009, 12:25 AM   #16
Site Supporter
Gregs's Avatar

Join Date: Jan 2008
Location: Sydney
Photos: Gallery
Posts: 52
Original Poster
Hi again.
After all the feedback I got from the forum, I’ve decided to have a go at this lens. (pic 1.)
Well it worked.
I also found out few things on the way which could make life easier for anyone who will attempt to play with these sort of lenses or similar M42 (pre set).
Throughout all this procedure, I did take some pics which probably will be some help to explain how to disassemble this or similar lens, and put it back together in the correct order. This is where you can find photos:
Fixing Lens 35mm f/3.5 42m - a set on Flickr

While doing so, I found the easy way to correct focus if someone has played with it before, and put it back together not paying attention to the helical threads.
The only thing left in situation like that, was trial and error, a kind of guessing game.
Then again, maybe I didn’t discover anything new, and every one is doing it the way,
as I described below?
You can decide for yourself.

At this point I have to tell you that English is my second language and maybe the way I try to explain won’t “grab” every one.
Sorry for mistakes if I missed some, while trying to correct it.

To dismantle back lens group, was straight forward.
It simply unscrewed from the back. (It’s easier when you take the T-mount off) (pic 2. & 3.)
First think I have noticed was that someone before, definitely had a go at it.
One “spacer” between lenses (pic4.) was not in right place, that just didn’t make any sense.
Later on, I decide that perhaps was in the right place, just should go another way around. (pic 5.)
But before I came to this conclusion I had changed the arrangement in the back group, at the same time gaining some 2mm between 2 lenses in that group. (pic 6.)
I reassembled the lens and took few picks…..
HUURAAAH!!!
First time the focus was there and focusing screen aligned itself as AF sensor confirmed that every think is in focus.
After further examination of the photos (100%crop and so on) the infinity still wasn’t as near as good, as one would expected, (which was especially evident at 100% crop)

(I’m maybe a bit crazy with checking everything at 100% crop)

I disassemble back group again (and as I sad before) put the spacer in the same position as I find initially, just another way around which at the same time fit to shape of the small lens and that make the only sense for this spacer being the. (pic 5. again)
I lost those 2mm again, hmmm….???
Back to square one.
For the very first time I decided to have look at the helical threads.
At this stage, the entire back lens group, was put together nice and clean, and I didn’t need to touch it again.
Getting in to helical threads wasn’t as hard as I thought. (pic 7. & 8.)
After several times of adjusting, putting together and checking the lens on my old ME super (for convenience instead of K20D) to see if the focusing screen aligned itself, I got a bit frustrated.
I thought, there must be easier way, and there is!!!!
What I have done is as follows:
I removed only the first ring which doubles as a focusing ring stopper. (pic 6.) & (pic8-ring on the right)
This way I could turn focusing ring as far as I wont to, till I found focus on focusing screen in my ME Super
Eureka!!!!!! I have now focus in my camera!!!!
On anything I focus in my room, I got a perfect focus 
But how I will know where and how the focus aligned on lens body, is this focus right according to focal range and how to reassemble the lens so that everything will be as should be?
Well, the trick to all this is to find on the lens what is the shortest focusing distance (every lens has it written somewhere, I think??)
In case of my lens, that was 0.9meter.
I improvise distance from step ladder, to corner of same sharp edge (door in my case).
Having done that, I adjusted focus to the stage that it was perfect at distance of 0.9 meter.
Then, without disturbing focusing ring, (which holds on to helical threads), I loosen up 3 screws which are holding focusing ring to helical threads.
That way you can freely turn around focusing ring without moving helical threads. (pics 8.)
Do not take it out, well you can but you will have to put it back to follow next step.

Having than that, I reassembled the first ring (pic 7.)
(which doubles as a focusing ring stopper)
I align the diamond shape read mark with corresponding red dot on top of the lens, above first aperture ring. (pic 1.)
Having done that, I secure this ring with 3 screws, (which were only loosened)
Then, without disturbing helical threads, align the focusing ring with the infinity mark stopping on the diamond shape mark (can’t go any further any way) (pic 1.) and secure with 3 screws. (which again, was loosened only).
That’s it!!!!!!
From nil focus on focusing screen to full focus from 0.09 to infinity,
(at least in viewfinder )
aaaaa ….don’t forget to put a T-mount back … (pic 9.) it is not important if is 180 degrease around as you always can loosen a little 3 screws when you have lens mounted on the camera and changed the position of your lens.
Actually it’s not important to mark any of parts you take a part, it will all “click” together (with exception to glass maybe)
I know, I know…… it’s confusing, I just read this what I wrote and I’m sorry for you gays 
.
Try to read again and look at the pics, and if you have any question don’t hesitate and ask
Will do my best to answer or explain.
I made some quick tests, same are 100% crop , none of the pics was alert with sharpness or anything else I just had to reduce size from 14mgp!!!
(silly me, forgot to change on K20D )
I will try to do more extensive tests later on, and try to discover the bouquet this lens can produce.
So far so good but still not entirely happy with infinity focusing.
Perhaps the lens requires some more fine tuning???
Cheers
Greg

08-16-2009, 12:52 AM   #17
axl
Veteran Member




Join Date: Mar 2007
Location: Nove Zamky, Slovakia
Photos: Gallery | Albums
Posts: 7,181
can you please post some bokeh shots?
I'd be really interested to see bokeh from 12 blades on 35mm lens.

btw: great job fixing it

BR
Peter
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!
aperture, blades, focus, k-mount, lens, pentax lens, slr lens
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Does wet oilly blades affect M42 lens performance hinman Pentax SLR Lens Discussion 9 03-17-2010 03:44 PM
Mystery 'PENTAR' lens? Charles_G Pentax SLR Lens Discussion 2 03-16-2010 12:57 PM
Does sticky/sluggish aperture blades on an M42 lens really matter? Peter Zack Pentax SLR Lens Discussion 13 10-04-2009 09:59 PM
For Sale - Sold: Soviet Tair-11A 135mm/2.8 Screw Mount M42 ( 20 Aperture Blades! ) arpaagent Sold Items 6 03-26-2009 05:23 AM
Mystery lens Bokeh Pentax SLR Lens Discussion 13 05-09-2008 06:02 AM



All times are GMT -7. The time now is 06:30 AM. | See also: NikonForums.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