need help: 300 2.8 AI apertures stuck

[brent_e]

Hi Folks,
I just grabbed this old beast from fleabay and haven't got my hands on it yet.  The aperture blades are stuck.  Has anyone taken one apart?  Any resources?

any help is appreciated! 

Brent

[Bjørn Rørslett]

First of all, are the aperture blades stuck fully closed down, in an intermediate position, or is the aperture wide open?

If you try to move the aperture coupling lever on the rear of the lens, do the aperture blades follow?

Just realised you might not have received the lens yet. However, do these suggestions first, then we can start working from those findings.

[brent_e]

First of all, are the aperture blades stuck fully closed down, in an intermediate position, or is the aperture wide open?

If you try to move the aperture coupling lever on the rear of the lens, do the aperture blades follow?

Just realised you might not have received the lens yet. However, do these suggestions first, then we can start working from those findings.

Hey Bjørn,
thanks for getting to this so quickly.
They're stuck wide open.  The lens shipped to a friend of mine (I live close to the border with the US so ship ebay purchases to a friend in NY) and he took a look at it.  It was affordable....so a bit of a gamble, but I've always wanted one of these.

No, haven't received it, but will get it monday.  the photos make it look like it's got damage on the mount which may have bent the coupling lever.  I'll post up here when I get some more information. 

by the by, any chance of buying a CPU for this lens???

Thanks again!

Brent

[Bjørn Rørslett]

These lenses are a breeze to put a CPU into. No problem with parts.

A bent coupling lever would easily result in a stuck aperture.

[brent_e]

I've searched online but can't find a manual for this.  Do you have any sources???  I don't mind buying one. 

[Bjørn Rørslett]

Not much of a need for a manual, at least for using the lens ...

Do you mean repair manual?

[brent_e]

ya!
I think I have the using part down!  Well....we'll see....

[richardHaw]

Hello, Brent.

Looks like I cannot find anything from the net as well. this lens is too exotic i think

http://page8.auctions.yahoo.co.jp/jp/auction/h228391254
is it this one?

[Bjørn Rørslett]

That certainly is what lens I observe in front of me, here at home ....

[brent_e]

Rick,
thanks for doing a search! 

It's surprising as it's not that crazy a lens!  it seems that there are quite a few of them around and quite a few for auction, as well. 

your link is to the AI-s version, which is optically the same (8 elements in 6 groups).  The one I purchased is AI and not AI-s, and made prior to 1982 from the serial number.

I'm hoping it's pretty straightforward to fix!  I'll certainly document the process and try to share it here. 

I'd still love to find a repair manual or schematic!  All i've got is a manual for the AF-I version, which is obviously a different build (AF, and 11/9 optics).

thanks again! 

Brent

[richardHaw]

That certainly is what lens I observe in front of me, here at home ....

how does it perform?

[richardHaw]

Rick,
thanks for doing a search! 

It's surprising as it's not that crazy a lens!  it seems that there are quite a few of them around and quite a few for auction, as well. 

your link is to the AI-s version, which is optically the same (8 elements in 6 groups).  The one I purchased is AI and not AI-s, and made prior to 1982 from the serial number.

I'm hoping it's pretty straightforward to fix!  I'll certainly document the process and try to share it here. 

I'd still love to find a repair manual or schematic!  All i've got is a manual for the AF-I version, which is obviously a different build (AF, and 11/9 optics).

thanks again! 

Brent

you bad boy, now i am hunting for one

is there a big difference between the 2?

[Bjørn Rørslett]

how does it perform?

It was a very good performer in its days and that hasn't changed. However, you probably would need to do a little removal of CA now and then. Digital cameras are more demanding in this respect than film ever required.

[brent_e]

you bad boy, now i am hunting for one

is there a big difference between the 2?

ooops!  sorry, brother!

there might be mine on the market if/when I get it fixed; not sure I have the room to keep it around!  Also, I'm going to try it with a TC16A, which apparently makes a reasonable 480mm f/4.5 with the ability to autofocus.

Brent

[brent_e]

I finally got my hands on this beast.  It has been dropped on the mount, which is not serviceable and also has some damage to the front elemet.  Thankfully I have a spare 180 2.8, which has the same bayonet.  I changed the mount out. 
I can assemble the lens but it jams up when the black tube/sleeve (the one that mounts inside the bayonet and is held in place by 3 tiny screws) is installed and the aperture does not work.  When the black tube/sleeve is removed I can mount the lens and shoot with it, but it stops down as I turn the aperture ring, telling me that it's not coupling with the camera properly.  Maybe the aperture lever is out of position and can't be held properly without the tube/sleeve installed.  After looking at a couple photos of the aperture lever on other samples of the same lens, it looks like it maybe be too short/bent from the drop.....that might be it....

anyone have any other ideas??? 

Honestly, I could probably use then lens as is.  I can still focus in dim light stopped down to f/8.

What a beast of a lens.  wow.


Brent