Sawyer's Mark IV / Primo Jr: removing front elements

[blee1996]

Greetings

I have a Sawyer's Mark IV (aka Topcon Primo Jr) TLR using 127 film. The shutter is sometimes slow between (1/250s to 1/25s), mostly due to the oil on shutter blades. 1/500s is fine, since it uses a much stronger spring. And speeds longer than 1/10s are also fine, since the slight sluggishness in the blades doe not add too much time.

The lowest cost solution seems to be removing the front elements, and clean the blades without disassemble the entire shutter.

I successfully removed the plastic ring using the rubber ring tool, and the first lens element pops out easily. However, unlike other similar Tessar lenses, the front lens group is not in a single unit. Behind the front element, and before the shutter, there is a second lens element. I cannot seem to find a way to safely remove the second lens element in order to reach the shutter blades, without further disassembly.

Anyone who had experience with this TLR model, could you please share your experience? Thank you in advance.

 

[monopix]

There's no way you will be able to remove the second lens element. You need to remove the whole front group as one assembly and, to do that, you'll need to remove the front of the camera. Start by removing the front leatherette. You'll find some screws underneath that hold the front of the camera to the front standard. You'll probably need to remove some other parts too. I've not worked on that model but all the TLRs generally dismantle the same way.

 

[Tel]

I have half a dozen Primo Jr/Sawyer's Mk IV cameras. I've done a good deal of work inside them. Monopix is right; you should remove the shutter from the camera to work on it. With this camera you can remove the front and rear lens groups separately, but the working space inside there is limited and doing what you plan to do inside it will be difficult. When you remove the leatherette from the front you'll see four small brass screws that hold it onto the front standard. When you remove them the front plate should lift off exposing the shutter/taking lens and the viewing lens above that. Then open up the back. You will see a black metal ring/tube thing on the rear of the taking lens--this is the shutter retaining ring, threaded to the shutter body, and by unscrewing it you'll release the shutter/taking lens as a unit. (You might need a spanner wrench to free this ring; there are two small slots for that purpose cut into it.) Once the shutter/lens assembly is off the camera, you can easily remove the front and rear lens groups leaving only the shutter. You should not have removed the front element; there is no need to do that. By twisting the entire front group housing counter-clockwise it will unscrew from the shutter; likewise the rear group.

If the problem is oil on the blades it may be fixable externally without opening the shutter. If it's an escapement problem you'll need to go inside.

A heads-up: the most difficult thing about servicing this camera is re-aligning the two brass pins on the back of the front plate that control the aperture and shutter-speed settings. In general it's a pretty robust and simple design that is fairly easy to work on. I love shooting with it, in general I prefer it to my Rollei Baby. Here are a couple of pics....

 

[blee1996]

Thank you both for the detailed response! I might attempt the repair if the situation does not improve or get worse.

 

[Tel]

The best way to clean oil off shutter blades is to open up the shutter and remove them, carefully cleaning each one and then replacing them in the correct order. A daunting task, especially on these small shutters. I have had some success with contact cleaner sprays to clean oil off the blades. A couple of times I tried this the result was spectacular. I use a contact cleaner I got from Tower Hobbies but others have reported good results with Deoxit. If you use Deoxit, make sure you get the deoxidizer spray, not the "Gold" conditioner. Deoxit Gold has oil in it; I sprayed some on a stuck set of blades a while back and covered them in sticky gunk. Had to dismantle the shutter and clean it out the old-fashioned way.