Mamiya C 80mm blue-dot disassembly

Hello,

Got myself a C330S that came with a fungus ridden taking lens, a 80mm blue dot. Does anyone have the dismantling instructions for this lens? I can see four screws on the back but would like a bit more info if possible before hacking it to bits!

Many thanks for any help!

I know that you don't want to hear this BUT leave dismantling a lens to a professional. You need special tools like a lens spanner to do this. Not only do you need to clean the fungus but to treat the lens to prevent a reccurence.

I opened up my C33 to affect a repair and closed it back up after seeing all those microscopic screws and sent it off to a proffessional. That being said, this guy has posted instructions for cleaning the 80mm lens:

https://www.iamthejeff.com/post/29/cleaning-a-mamiya-tlr-lens

As much as any DIY camera/lens repair can turn into a pile of scrap, I've successfully cleaned many Mamiya TLR lenses, and even repaired a C220 that I dropped and jammed up the film advance on, with limited tools, and as much info from the webternet as I could find.

Most of the Mamiya TLR lenses are 4 sections of lens groups; in front of the shutter on the taking, behind the shutter on the taking, and a front and rear section of the viewing. Each section unscrews from the assembly individually, and each section will have a group or groups of lens elements.

I have found that on most of the M-TLR lenses, the viewing and taking sections are interchangeable. I'm sure others will argue this, but I have swapped the front of a viewing lens that was good with the front of the taking lens that had severe separation and scratches, and the lens works just fine. You would really only want to swap within the same lens though, as they would be calibrated for one another. Mixing from a different lenses may throw off focus, and then it's a game of focus calibration (at the least).

If the optics of the viewing lens on your lens is good, but the taking lens is suffering from fungus, scratches, haze, separation, etc., it may be worth trying the swap.

I've found, in most instances, that the fungus is easily accessible once you unscrew the sections from the lens assembly. Usually no need to open up the groups for just fungus. It tends to be on the back side of the front grouping, or the front side of the rear grouping, making cleaning easy.

To remove the front section, just grab the front, and unscrew. That's it. No special tools needed. To access the front of the rear lens, if you don't have a spanner, take of the front, open the shutter by using a locking cable release with the shutter set on B. Clean the element, and close everything back up.

Now if you want to get in between elements of the sections, you'll need a spanner, and it's just like any other lens, just smaller.

I say go for it yourself, and just be patient. It isn't like disarming a bomb, it's just a bunch of stacked glass screwed together.

pbromaghin said:

I opened up my C33 to affect a repair and closed it back up after seeing all those microscopic screws and sent it off to a proffessional. That being said, this guy has posted instructions for cleaning the 80mm lens:

https://www.iamthejeff.com/post/29/cleaning-a-mamiya-tlr-lens

Click to expand...

These are instructions for the older chrome lens and not the blue-dot black lens. The two may be similar enoughfor the article to be of use, but ... Professionals dismantle a lens in a dust free environment like you would a watch. The average person can't do this. There is an amazing amount of dust and other stuff in the air we breath.

Oh, the rear element sections are held on with retaining rings, so if you want to remove them, you'll need a spanner.

Gerald C Koch said:

These are instructions for the older chrome lens and not the blue-dot black lens. The two may be similar enoughfor the article to be of use, but ... Professionals dismantle a lens in a dust free environment like you would a watch. The average person can't do this.

Click to expand...

Gerald, lenses aren't assembled in dust-free clean rooms, so why would a repair need to be done in one? Clean the lens as you're reassmbling, and there won't be significant dust. There is no lens out there that doesn't have dust in it. They aren't air-tight, and I personally have yet to see a lens that didn't have dust in it when a flashlight was held up to it. Just sayin'.

The shutters on the Blue-dots may be different then the chromes, but the basics of assembly and disassembly of the lens elements for access/cleaning are the same. (I have both)

film_man said:

Hello,

Got myself a C330S that came with a fungus ridden taking lens, a 80mm blue dot. Does anyone have the dismantling instructions for this lens? I can see four screws on the back but would like a bit more info if possible before hacking it to bits!

Many thanks for any help!

Click to expand...

That lens requires no spanner. Even a kid can do it. The front and rear lens groups just unscrew by hand.

I have done it lots if times.

film_man said:

Hello,

Got myself a C330S that came with a fungus ridden taking lens, a 80mm blue dot. Does anyone have the dismantling instructions for this lens? I can see four screws on the back but would like a bit more info if possible before hacking it to bits!

Many thanks for any help!

Click to expand...

PS: Chances are the fungus is between the front and rear lens groups. For cleaning the final lens element you neef a spanner. A verner caliper is a makeshift spanner for this.

Have yet to see a repair shop with a dust free environment. Manufacturer maybe. Independent? Not likely.

Sorry should have added this I suppose, I'm not actually that bothered if I junk the lens, as I will be buying another one. The fungus seems to have eaten into the glass so
a. it cannot really be repaired
b. paying someone to do it is more than buying another one

So I'm treating this more as a learning exercise than something with a usable outcome. If I end up with a useable lens in the end even better!

As for dust free environments...come on, have you ever seen a workshop bench?

PS
Merry Christmas!

Buying another lens? Heck, go for it!

dust free environment?... hahaha i keep a clean shop but its not hepa filtered air by no means.

if you have nothing to lose in diy repair, go for it! i inspire people to diy. especially at the cost of repair vs replacement these days....

besides, the more people diy, the more recycled still very usable equipment will be available to serious hobbiests. not many pros using this old stuff anymore.

if you swap the viewer for taker, swap the entire lens, not just a cell. you'll also have to recalibrate the user n taker to focus the VF and agree with the film plane.

btw, there is a difference in optics from viewer n taker... coatings for one n less elements in a viewer, its not as critical as the taker. some tlrs, the viewer is a single unit and is focused by screwing it in or out n set in place by a set screw.

but, the viewer will take beautiful pictures regardless.

film_man said:

Sorry should have added this I suppose, I'm not actually that bothered if I junk the lens, as I will be buying another one. The fungus seems to have eaten into the glass so
a. it cannot really be repaired
b. paying someone to do it is more than buying another one

So I'm treating this more as a learning exercise than something with a usable outcome. If I end up with a useable lens in the end even better!

As for dust free environments...come on, have you ever seen a workshop bench?

PS
Merry Christmas!

Click to expand...

Most fungus will just clean away easily.
And if they don't, just use toothpaste to polish the lens surface until the fungus comes out. Seriously.

Lens coatings are really really tough