Tamron SP 70-150mm f2.8 Soft Focus apperture Problem

MinniMe · Joined: 14 Mar 2020 Posts: 12

Hi everyone Smile

First of all I´d like to apologize since I´m not native english speaking.

I´ve purchased a Tamron SP 70-150 2.8 soft focus. Was a real bargain.
At home I´ve discovered that there is something strange with the Lens. I cannot completely open the apperture when the Lens is attached to the T2 to Knoca AR Adapter.
Without the Adapter the apperture stays completely open. When I attach it, even at 2.8 it seems like the apperture is at f4 or something like that.

First thing I did was checking the Adapter ring since this is adjustable. It was set to 2.8, so everything should be fine.
Next thing was Lens set to 2.8 without adapter (so apperture is fully open) and then I pressed the pin (correct term?) on the backside and again the apperture closes to f4 or something like that.

I hope everyone understands what my problem is Smile

So my question is, is the apperture control broken? is this not a bug but a feature? Can I fix this? are there repair shops who still repair those lenses?

MinniMe · Joined: 14 Mar 2020 Posts: 12

Okay, now I guess the problem is even bigger -.-* I just had the lens with an adapter on my camera to do some test shots.
turned the apperture ring a few time to step down and now the apperture closes completely down to f32 when on the adapter, no matter which aperture is set...

Maybe something broken? Worth to repair?

Ultrapix · Joined: 06 Jan 2012 Posts: 551 Location: Italy

I don't know if what I am going to say could be useful to you, but... let's try.

The mount of that lens is badly engineered. The lens is heavy, and the chrome brass ring that support the Adaptall mount is largely undersized. So it is common for this lens to acquire a play that can be easily found simply by pulling it to the right or left when mounted on the camera. Then if the ring doesn't fit the lens perfectly, you may not be able to reach full aperture.

just a guess, try it and let us know

MinniMe · Joined: 14 Mar 2020 Posts: 12

Nope, the Apperture just stays closed now with the Adapter attached. No Control at all, no matter which apperture.
Without the Adapter the apperture stays open an 2.8...

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Ultrapix · Joined: 06 Jan 2012 Posts: 551 Location: Italy

well, I'd say that only the Adaptall ring is faulty then

MinniMe · Joined: 14 Mar 2020 Posts: 12

Well, when I remove the adapter Ring, press down the apperture Pin on the back now and change the apperture nothing moves. Always stays on smallest apperture... So this also happens without the adapter...

e6filmuser · Joined: 12 Nov 2010 Posts: 582 Location: Reading UK

MinniMe · Joined: 14 Mar 2020 Posts: 12

Okay, maybe I have described it the wrong way. I try it again, but anyway somehow after "playing around" with the apperture Ring the Problem has Changed...

Without the Adapter Ring the Apperture is wide Open. I change the apperture on the ring and nothing happens. The apperture stays wide open.
I connect the Adapter RIng and the Aperture closes down to f32 or whatever the smallest aperture is.

So without Adapter Ring -> wide open
with Adapter -> fully closed to smallest aperture.

No matter what I set on the aperture.

MinniMe · Joined: 14 Mar 2020 Posts: 12

Apertureblades as clean as they can be... no oil...

kypfer · Joined: 27 Sep 2017 Posts: 516 Location: Jersey C.I.

MinniMe · Joined: 14 Mar 2020 Posts: 12

kypfer · Joined: 27 Sep 2017 Posts: 516 Location: Jersey C.I.

MinniMe · Joined: 14 Mar 2020 Posts: 12

Yeeahh

I found the Mistake. Just screwed the lens open.

The spring ring (sorry for my bad english, I dont know the correct technical term) should be sitting on the disk which moves the pin to secure it from slipping away (seen in picture 2 and 3).
So iI was just moving the Pin, putting the disk back in place and securing it with the spring ring.
The hardest part was placing the spring, making sure the disk was still in place and putting the spring in the right place all at the same time.

I dont know if everything is 100% correct. in picture 4 you can see the aperture when its set to 2.8 and the pin is pressed. I guess the spring was not set correct, but at least the apperture is moving. Maybe someone owning one can confirm if the aperture with 2.8 open and adpter attached is correct this way (what I dont think) or if its not correct.

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Oldhand · Posted: Sun Mar 15, 2020 1:27 am Post subject:

Well done to find the problem.
At least your lens is now functional.
T

e6filmuser · Joined: 12 Nov 2010 Posts: 582 Location: Reading UK

MinniMe · Joined: 14 Mar 2020 Posts: 12

Good morning,
I opened the lens once again because I didnt properly secure the spring last time... silly me...

I checked the aperture mechanics again and I was able to slightly improve the aperture. As seen in the pictures is the best where I get.
It seems to me I do not have any more room for improvement because, well... mechanic says 'no'. Guess I will once more search the Internet for any more Information about this lens or Tamron aperture mechanic to restore this to 100%. Or just call Tamron and ask friendly if they can help Very Happy

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e6filmuser · Joined: 12 Nov 2010 Posts: 582 Location: Reading UK

Anyway, this may be of general use:

http://www.adaptall-2.com/lenses/51A.html

(Note to admin, the reply button for this string kicks me to the Home page. I have to used quote).

I am editing this reply and I cannot access this string as a new reply or a quote.

Back in the 80s I was buying Tamron SP lenses as they were issued. This one was promised for a very long time. Ever since it was made it has been an extreme rarity, in my experience, perhaps because few were made, but I have not found evidence for this.

Lucse · Joined: 22 Jul 2015 Posts: 166 Location: EU

Edit: posted in wrong thread, sorry.

MinniMe · Joined: 14 Mar 2020 Posts: 12

Wohooo

Managed to repair the lens.
The disk which moves the pin was ever so slightly bent. Just a tiny tiny bit of pressure and now everything works just fine Smile

Also had the opportunity to clean the lens inside while it was open.

Now lets see what this puppy can do and if it is a keeper Smile

I also looked up the prices which are asked for this lens.... ridicilous or it is one of the best ever made.

kypfer · Joined: 27 Sep 2017 Posts: 516 Location: Jersey C.I.

visualopsins · Expire: 2025-04-11

MinniMe · Joined: 14 Mar 2020 Posts: 12

Opened it hopefully for the last time.
The disk moving the Pin can be very easily lubricated with a pencil...

Now the first testshot

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e6filmuser · Joined: 12 Nov 2010 Posts: 582 Location: Reading UK

MinniMe · Joined: 14 Mar 2020 Posts: 12

Arutemu · Joined: 16 Oct 2014 Posts: 72 Location: US/Japan

Darn, I just purchased the same lens and it has the same problem. The aperture gets closed as soon as an adapter is attached and I lose control of it - it stays closed and cannot be opened. I also noticed that the mount on mine looks different from the pics above. It is lacking the rectangular opening rear baffle. Is that a different version of the Adaptall mount I am not aware of, or am I screwed and the lens is missing its rear? I paid $20 for it, so no big loss, but I really wanted to make it work...

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