Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
12-29-2011, 07:04 PM   #16
Site Supporter
jatrax's Avatar

Join Date: May 2010
Location: Oregon
Photos: Gallery | Albums
Posts: 10,285
QuoteOriginally posted by Mike Cash Quote
"Constant" aperture applies only to zoom lenses, not primes. On a prime there is no focal length range for the aperture to be "constant" through.
Correct, I typed faster than my brain was working.

12-29-2011, 07:45 PM - 1 Like   #17
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 885
Observing the image you posted... are the blades to the aperture really in different shades? No oil stains?

QuoteOriginally posted by David-C Quote
Not a ding, dent, scratch, dust particle... nothing. It's honestly as though it just came out of the box.
Not impossible to open a lens and clean things out, but closed it wrong.

Because it sounded like the aperture ring will not move a tiny bit at all. Try checking it on a large flat surface to see if the lens was assemble wrong or bent from abuse. Rest the lens on it's side and slowly roll it, but start where the white bump will arc up and around so as to not make the lens hop. Monitor if the barrel is off or crooked or off round since you said the lens shows no signs of dents. It is not impossible that someone took it apart and cleaned it and had trouble locking the internal tab of the aperture to the ring. Note if the rubber grip to the focus part of the lens is not even with the edges of the metal barrel... I forget if the K200mmF4.0 had an adjustable focus scale via a clamp.

If the lens is running off true, then you should not force the aperture ring or risk the inner tab of gouging the important bits of the aperture ring. Another thing to make sure is if the mount is bent or warped.

QuoteOriginally posted by David-C Quote
Mike Cash>> Thanks, your post came up as I put up my reply. Considering the situation of, lever working but ring not working, would you suppose it could be fixed by a tech-guy, or would you think it and I are up a creek?
Inside is a cam like slide in many Pentax lenses and if nothing is spotted from any of the tests, then it could be that the cam is disconnected from the slide inside. That is usually an easy fix.
12-29-2011, 08:32 PM   #18
Junior Member




Join Date: Dec 2011
Posts: 41
Original Poster
Just gave it a thorough inspection as per your suggestions.

The knurled barrel of the lens is still true from what I can tell. I think that it is possible that the area where the focus ring is, could potentially be out of true, but the variance seems so tiny as to make me question how true my 99 dollar ikea desk is. If the variance is real, it has to be on the order of 1/50th of an inch.

From what I can tell the mount is just perfect.

I am not aware of any rubber on the lens at all. The large focus ring is knurled metal with a chrome ring at the end.

I think I have resigned myself not to attempt to move the ring again, especially at your recommendation. It appears there are a few repair shops in the Toronto area so I will print off your remarks and take the lens in to see one of them.

The aperture blades appear flawless when inspected under the light, consistent colour to each blade, no signs of oil spotting. The inside of the barrel is a flawless gunmetal grey colour.

Thanks very much for lending your expertise. As a beginner I do not even know what to expect or inspect, so at least I can have some gauge of the issue and technician. Its nice to know there is some hope for this lens and a simple solution.

Word to the wise, do not attempt to achieve anything approaching useful results with a macbook pro camera.. Seriously, I keep looking behind the screen to find the shoebox.
Attached Images
 
12-31-2011, 12:31 PM   #19
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 885
As a after thought... I hope someone didn't fudge the levers inside to make it more compatible with a digital? I don't suppose there are suspicious holes drilled along the chrome surface of the bayonet mount... it is the surface that faces the camera and has the screws. I've heard of some people who modify the older lenses to work in shutter priority mode.

12-31-2011, 10:48 PM   #20
Site Supporter




Join Date: Oct 2010
Location: Melbourne
Photos: Gallery
Posts: 2,823
Hi

From the picture I see Ap.Ring sits at 32 (smallest hole) blades. You say the actuation lever at the mount end of the lens works which means you can open the blades.

Just at an off chance.
You say you can't turn the Ap.Ring, but try this and see if the ring turns then:
Move the lever so the lens is wide open and while you hold the lever in this position try to move (turn) the Ap.Rring to F:4 where it actually should sit when wide open. While you are holding the blades open some mechanics inside the lens may become aligned such that it allows the ring to move again. Worth a try.

Greetings
12-31-2011, 11:39 PM   #21
Junior Member




Join Date: Dec 2011
Posts: 41
Original Poster
MysteryOnion>> Nope, there are no suspicious holes there, fortunately.

Schraubstock>> I gave it a go, but she did not budge.

I sent off emails to about 5 different places here in Toronto a couple days ago, but due to the time of the year only one has gotten back to me. He said it could be corrosion. He also indicated a price range from 60-90 CND to repair it, with the issue ranging from simple-to-complicated.

Whenever I get it in somewhere, I will be sure to post the results.
01-01-2012, 11:16 PM   #22
Junior Member




Join Date: Dec 2011
Posts: 41
Original Poster
ATTN MysteryOnion

MysteryOnion>>

I tried to respond to your PM but apparently you do not accept PM's in your settings, so I will just copy and paste my remarks here:

Thanks for the extremely nice offer. I have to say, I have been really impressed with this forum, a lot of genuinely helpful people here much like yourself.

Thanks very much for the info, I really hate going into anything ignorant and you have given me something to work off of, particularly the price analysis. From what I can gather these tech people can be a little hit or miss, so I am going to try and sift through the prices, details and first impressions to see what turns up around here. Your info will be invaluable to this extent. Incidentally, I am in the economics and finance department, but my school is well known for photography so I am going to see what resources the film department may have.

If all my efforts start to seem a bit futile, I would be very thankful for your kind offer.

Have a great new year,
Dave
01-02-2012, 07:37 AM   #23
Giveaway winner!
MysteryOnion's Avatar

Join Date: Dec 2007
Location: beantown
Photos: Albums
Posts: 885
Dave, sorry about that... I used to get PM's and had not monkeyed with the settings, but I'll put it back to right by officially monkeying with it.

I figure you may find an enthusiast for film there at your school who may even be in the "FPP" crowd... I recall one or two from Toronto.

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, camera, center, exposure, lens, lenses, moon, pentax, pentax help, photography, shutter, time
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fixed aperture bracketing in M Karl Stevens Pentax K-5 17 10-30-2013 08:06 PM
Can a manual m42 mount lens with a stuck aperture be fixed? Vantage-Point Pentax SLR Lens Discussion 3 09-15-2011 08:54 PM
Fixed aperture manual lens help Joe Troubleshooting and Beginner Help 7 09-01-2010 10:38 PM
Fixed-aperture lenses Adam Pentax SLR Lens Discussion 4 05-29-2010 10:26 PM
Disconnect lens and keeping aperture fixed D0ri Pentax SLR Lens Discussion 7 05-24-2010 11:48 AM



All times are GMT -7. The time now is 09:55 PM. | 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