Micromega grain focuser mirror spare part?

Jerevan · Jun 25, 2019

I have an old Micromega grain focuser that I have had for years. It must be quite old, since it was well used when I got more than ten years ago.

It has a sticker that says "Prof.Z.Koana system" so I guess the Z is for Zen.

Does anyone know if one can get a new mirror for this? Or maybe one can get a front surface mirror (if it is front surface coated, don't know) cut to size?

chip j · Jun 25, 2019

I got one for mine, years ago. Probaly online, I don't remember.

Hilo · Jun 25, 2019

Depending on which model you have: you can take out this mirror and turn it around . . .

AgX · Jun 25, 2019

With a lot of old cameras and other stuff around, respectively are first surface mirrors too.
Of course the substitute mirror should have the reflective surface at same position (think of mirror thickness).

Ian C · Jun 25, 2019

Mirror for Model 1

https://www.bhphotovideo.com/c/product/135286-REG/Peak_EPK200M_Mirror_for_Critical_Enlarging.html

Blue Eyepiece Filter (special order)

https://www.bhphotovideo.com/c/product/41092-REG/Peak_PK2020BG_Blue_Filter_for_Critical.html

Regarding the comment “It has a sticker that says "Prof.Z.Koana system" so I guess the Z is for Zen.”

I think (but am not certain) that the designer of the pivoting-eyepiece grain magnifier was Dr. Zyun Koana, Department of Physics, Tokyo University. I found some Internet information indicating that he was a member of the Department of Optics at Sophia University Tokyo later in his career after mandatory retirement from Tokyo University at the age of 60. He is mentioned several places in the notes of Rudolph Kingslake (head of the Optical Design Department, Eastman Kodak).

https://redbook-jp.com/redbook-e/koana/index.html

https://redbook-jp.com/redbook-e/koana/k50.html

If I haven’t referenced the wrong Professor Z. Koana, the Z is the initial of his given name, Zyun, as rendered in English.

markbau · Jun 25, 2019

Worth pointing out that over the years the worth of the blue filter has been hotly debated. Nocon said it was a must but no less than CTEIN said it is a waste of time. I went with CTEIN and put mine in the spare parts drawer, I did try it a few times and found that it was very hard to focus with it. It was easier with the lens wide open but who focuses with the lens wide open? Personally, I don't think the blue filter is worthwhile.

BTW, looks like a new company is making them now.
https://www.amazon.com/Peak-Model-1-Enlarging-Focuser/dp/B00K339M9E

Ian C · Jun 25, 2019

So far as I can determine, Peak is a brand used for marketing a variety of optical devices that includes magnifiers of many different types made by

Tohkai Sangyo Co. Ltd.
16-13 Yushima 3-chome
Bunkyo-ku
Tokyo 113-0034
Japan

I believe that it’s still in business and has been operation since its formation in 1951.

https://www.photonics.com/Buyers_Guide/Tohkai_Sangyo_Co_Ltd/c15078

AgX · Jun 25, 2019

http://www.peak.co.jp/index0.html

Patrick Robert James · Jun 25, 2019

markbau said:
Worth pointing out that over the years the worth of the blue filter has been hotly debated. Nocon said it was a must but no less than CTEIN said it is a waste of time. I went with CTEIN and put mine in the spare parts drawer, I did try it a few times and found that it was very hard to focus with it. It was easier with the lens wide open but who focuses with the lens wide open? Personally, I don't think the blue filter is worthwhile.

BTW, looks like a new company is making them now.
https://www.amazon.com/Peak-Model-1-Enlarging-Focuser/dp/B00K339M9E

Nocon printed on graded papers. I had a few discussions with him about it back in the day and he never said it was a "must", at least not to me. I never used the blue filter myself, but I use VC papers.

I focus with the hard light (magenta/blue) and that definitely works. If you focus with the blue filter and use white light it is the same thing. The most accurate, and most difficult, way to focus is with blue light, but that assumes blue light will be the majority of your exposure. With VC paper it may or may not be.

Jerevan, I have the same magnifier as you and the back of the mirror definitely isn't silvered. You just need a front surface mirror cut to the right size. If the one that someone linked to at B&H above fits, then just get that.

Jerevan · Jun 25, 2019

Thanks for all the information, gentlemen!

I have to take it apart and see if it is possible to just flip the mirror around. I have to measure the thickness and size - it is the long version as far as I understand it. I was thinking of getting a mirror cut, but the B&H option could be just the right thing. With the prices on Ebay and elsewhere, I think I am going to just repair it ...

Sirius Glass · Jun 25, 2019

Ian C said:
So far as I can determine, Peak is a brand used for marketing a variety of optical devices that includes magnifiers of many different types made by

Tohkai Sangyo Co. Ltd.
16-13 Yushima 3-chome
Bunkyo-ku
Tokyo 113-0034
Japan

I believe that it’s still in business and has been operation since its formation in 1951.

https://www.photonics.com/Buyers_Guide/Tohkai_Sangyo_Co_Ltd/c15078

After spending money on more than a few grain focusers, I found that one purchase of a Peak grain focuser was well spent money, the only one I use.

logan2z · Jun 25, 2019

Sirius Glass said:
After spending money on more than a few grain focusers, I found that one purchase of a Peak grain focuser was well spent money, the only one I use.

+1 being able to check focus into the corners of the print is worth the price of admission.

Hilo · Jun 26, 2019

Jerevan said:
Thanks for all the information, gentlemen!

I have to take it apart and see if it is possible to just flip the mirror around. I have to measure the thickness and size - it is the long version as far as I understand it. I was thinking of getting a mirror cut, but the B&H option could be just the right thing. With the prices on Ebay and elsewhere, I think I am going to just repair it ...

If by long version you mean the mirror is a long vertical, then I think you can just unscrew the two screws underneath. They hold in place two metal clips that stabilize the mirror into place. I just had a look without unscrewing and I think the mirror is resting on a black metal plate. You will just need to turn the mirror IF indeed there's mirror on the flip side . . .

AgX · Jun 26, 2019

I never saw a doublesided first-surface mirror. But I like that idea of integrated spare.

Jerevan · Jun 26, 2019

Hilo said:
If by long version you mean the mirror is a long vertical, then I think you can just unscrew the two screws underneath. They hold in place two metal clips that stabilize the mirror into place. I just had a look without unscrewing and I think the mirror is resting on a black metal plate. You will just need to turn the mirror IF indeed there's mirror on the flip side . . .

Yep, it is long vertical - gotta have a look (runs off getting a screwdriver) ...

Jerevan · Jun 26, 2019

What you get when you back the screws out and take out the mirror are two pieces.

One metal (?) foil which one side is black (underside) and the other side is silver colour, facing upwards, towards the glass piece. The mirror is a thick piece of glass, front surface coated, but turning it around gives you another mirror surface - that is, it's not blackened as would be the standard procedure I guess.

Hilo · Jun 26, 2019

Yes, I just opened mine and found the same. I now remember who told me this existence of a mirror on the flip side and will ask him if he actually checked if it worked.

Something else: your mirror is still in one piece. Why don't you clean it carefully? Use very soft cloth for that, not antic static ones. I have worked in many darkrooms and met many dirty Peak focusers. But I always got them to work properly. I see maybe you have two small damage lines on the surface. Those probably won't interfere . . .

Jerevan · Jun 26, 2019

I'll try to clean it off a bit - it was mostly the largish chip in the mirror on top that bothered me somewhat. Tried to put it in with the chip on the lower end, but it doesn't fit.

AgX · Jun 26, 2019

Jerevan said:
The mirror is a thick piece of glass, front surface coated, but turning it around gives you another mirror surface - that is, it's not blackened as would be the standard procedure I guess.

Front-surface mirrors typically are not blackened or otherwise varnished at their back (there is no reason for such anyway).

So be aware not to be fooled by the front surface to impress as another reflective surface on the back. Looking at the edges of the pane will show you the position of the reflective coating.

Hilo · Jun 26, 2019

AgX, you are right. I was probably too believing in this story. Anyway, I have written the source of this story, let's see what he comes back with.

By the way, the smaller and cheaper Peak II focuser is really excellent too. It is easier to use in the semi dark, less heavy and still works quite close to the corners.

Hilo · Jun 28, 2019

Heard back from the man who told me you can turn around the mirror of the Peak: unfortunately it is not conclusive. He turned the mirror around and did not try it out. Instead he sold it . . . and that's the end of that story.

I wonder if I should turn mine around and try it. Or just forget about it.

EdSawyer · Jun 28, 2019

if you turn it over, it's not going to be accurate, since the surface of the mirror will be in a different place. Just get the replacement part from B&H or elsewhere.

Patrick Robert James · Jun 28, 2019

EdSawyer said:
if you turn it over, it's not going to be accurate, since the surface of the mirror will be in a different place. Just get the replacement part from B&H or elsewhere.

Yup.

The "mirror" you are seeing on the other side Jerevan is just the reflection of the one sided mirror. It is clear in the pictures you posted. If you want to check a front surface mirror, hold a pencil on the surface. If the pencil tip touches itself, then it is a front surface mirror. If it doesn't, it isn't.

Like Ed said, if you flip the mirror, it will be wildly inaccurate.

Hilo · Jun 29, 2019

Thanks all ! Saves me doing something that does not make sense . . .

RalphLambrecht · Jun 29, 2019

Jerevan said:
I have an old Micromega grain focuser that I have had for years. It must be quite old, since it was well used when I got more than ten years ago.

It has a sticker that says "Prof.Z.Koana system" so I guess the Z is for Zen.

Does anyone know if one can get a new mirror for this? Or maybe one can get a front surface mirror (if it is front surface coated, don't know) cut to size?

just fet a new used one.

Micromega grain focuser mirror spare part?

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