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Classic Camera Repair » Archives-2004 » Aperture Problem with Minolta SRT 101/Rokkor-PF 1:1.4 Lens « Previous Next »

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Katie

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Posted on Thursday, November 04, 2004 - 11:07 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hello Folks - I just stumbled across this forum and it looks terrific! Glad to find you, although until now, I have been fortunate to never need any real camera work on either my Nikon FM or FM2... But I got a free Minolta SRT 101 yesterday. As best as I can tell, its only problem may be that the aperture doesn't shut down. It stays fully open all the time. The first problem I noticed was that the depth of field (DOF) preview wasn't working... then I saw that the aperture adjustment isn't either. I have tried gentle jostling of the lens and working the spring-loaded pin on the back of the lens, trying to "loosen" the aperture blades up, if that is the problem, but to no avail. Other ideas?

I will add that when I try to push the DOF preview button in, it doesn't seem to feel right. It sort of crunches in every other attempt. I think the crunchy push is either DOF on or off, and the alternate, normal-feeling push, is the other (on or off).
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rick oleson

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Posted on Thursday, November 04, 2004 - 11:32 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

the most likely cause of the stuck lens is oil on the aperture blades, and to free them the lens really needs to be disassembled so that the blades and actuating ring can be reached. the SRT DOF button does have an alternate apply/release action to the control; not sure whether the "crunchy" feeling might be normal or not.
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Katie

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Posted on Thursday, November 04, 2004 - 11:44 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thanks, Rick. I read through another posting about a similar situation that you also responded to (https://kyp.hauslendale.com/classics/forum/messages/674/342.html?1050639072), but the talk about ball bearings and such is a little scary. I have had ball bearing problems on bikes and such in the past - not my favorite adventure... Is disassembling this puppy going to yield lots of little parts falling out, or is a bit more manageable? I am not scared of taking a few screws out, but then... not sure. Which screws do I start with, anyway? The black screws just outside the actual lens or the silver outer screws? Would removing the proper set give me a good idea of what I am getting into, or will I not know I am in over my head until it is too late? Thanks so much!
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Don

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Posted on Thursday, November 04, 2004 - 12:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

IIRC, you have to cock the shutter in order to use the DOF. To add to Rick's post, check the aperture blades under a good lite. If they look shiny, then oil is the problem.
Don
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rick oleson

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Posted on Thursday, November 04, 2004 - 12:10 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

oh yeah, i forgot about the ball bearings in the minolta lenses. i'll take a look at my sketches at home and see how difficult this looks.

: ) =
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Katie

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Posted on Thursday, November 04, 2004 - 12:13 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Thanks again.. On the DOF preview... if the shutter is not cocked, pushing the button is always the same and is smooth. When the shutter is cocked, as it should be, the first push is the crunchy one (I assume that is DOF preview ON) and the 2nd one is smooth. And this alternating sequence is the same until I push the shutter release and reset things.

For anybody with a smoothly operating SRT 101, does this crunchy sound/feel seem odd? And if it is odd (which it really seems to me that it is), does it make any mechanical sense that it would be related to the aperture blades being stuck? This camera is quite clean and the shutter action is super crisp, so I am hopeful a blade cleaning will make it a jewel again...
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Katie

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Posted on Thursday, November 04, 2004 - 12:19 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

OK.. so one more observation about this lens... The spring-loaded pin on the back of the lens, which I assume engages with the camera body to adjust the aperture opening, pushes very easily about half the distance, and then the spring provides some gentle resistance the rest of the way. Is this normal? Or should the spring provide resistance throughout the pin's movement?
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rick oleson

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Posted on Thursday, November 04, 2004 - 02:43 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

i have 2 of these sitting at home, i'll look and get back to you. as i recall, on one push of the DOF button it has a sort of click at the end of the stroke, and on the next push it doesn't. so that much i think would be normal.....
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rick oleson

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Posted on Thursday, November 04, 2004 - 04:14 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi, me again.

First, the behavior of the stop-down pin of the lens you describe is normal. The spring resistance increases about halfway through the stroke.

Second, the stop down button on the body: It only works when the shutter is cocked; on the stop-down stroke, the button can only be pushed about halfway in, at which point it clicks (it feels something like the button on a ball point pen) and the lens snaps down to shooting aperture. On the reopen stroke, the button presses in smoothly, all the way to the body casting.

Third, servicing the lens; good news and bad news. The ball bearings are at the rear, and you PROBABLY don't have to go there to clean up the diaphragm. Most of the mechanism is reached from the front. The bad news is that this is probably not the easiest of all lenses to service. But it is doable, I have sketches for it, and I'll be happy to send you scans if you'll email me for them.
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Simon Lister

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Posted on Sunday, November 07, 2004 - 05:52 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi, I've just found this forum after being a SR-7 which used to belong to my grandfather, and its lens has the same problem. Would you mind sending me a copy of your sketches also (I'll send you an email). Thanks.
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Sam

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Posted on Tuesday, December 21, 2004 - 10:11 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hi, Katie,

Usually, I don't recommand people to do the repair if they don't have the experience, it will be so easy to be end up to destroy the camera. so this is only to give you some idea, you think about it yourself. Since you have a problem to open the lens, I have one web site to show how to open a minolta lens, the address is http://sa-ss.hp.infoseek.co.jp/index1.html. it is in japanese, you may guess what they say, I don't know japanese neither, hope it can help you.
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Sam

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Posted on Tuesday, December 21, 2004 - 10:20 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

By the way, what type of lens is it, a MC, MD or auto? it should be marked on the lens. when you try the pin at he bottom of the lens, you have to make sure you had turned the aperature ring to the smallest position such as 16.
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Katie

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Posted on Tuesday, December 28, 2004 - 11:35 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

Hey Sam, Simon - sorry for such a delayed response - I haven't been on the forum for AWHILE!

Sam, the lens is an MC and I have been on the website. I am pretty excited to try the work, but don't have a lens wrench, nor any tools to create one, so it is definitely on hold for awhile. sigh.

Simon, did Rick happen to send you his sketches? If not, let me know. I don't think he'll mind me forwarding them to you.

Unfortunately, I have a bigger problem now - my BABY - my Nikon FM that has been my mainstay for 11 years - decided to "croak" December 25... More on that in a new thread. UGH.
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Paul Jenner

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Posted on Friday, December 31, 2004 - 09:28 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Moderator/Admin Only) Ban Poster IP (Moderator/Admin only)

I bought a lovely MC-Rokkor 85 mm/1.7 today. There definately is oil on the blades.

Someone still have these pictures for taking this baby apart ?

Regards,

Paul.

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