Minox Day Light Development Tank

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Minox tank models.

Minox tank hydrodynamics

-- martin tai (martin.tai@capcanada.com), December 21, 1998


The Minox daylight development tank is another masterpiece by Walter Zapp. Early Riga Minox tank is rare collector item. There was one on auction about a month ago on Ebay. During the days of Minox B , the Minox tank has 50 exp maximum capacity. I saw one such 50 load Minox tank 2 years ago after I bought a new 36 load tank; I reget not picking up that one. Current Minox tank is 36 load variety, it comes with a fill ring used for 15 exp film. A Minox thermometer is used to pump the developer at the centre well for agitation. The nice thing about Minox tank is that it permits loading of Minox film casette into the tank at daylight, develop at day light. The developer capacity of Minox tank is 55 c.c. Which is adequate for developer used at normal strength, such as D76 for Agfapan APX 25. But when it comes to Technical Pan film, there is a problem, one cannot use normal strength developer, as the resulting negatives have extremely high contrast, not printable even with -1 grade filter. My first rounds of attempts to develop Techpan in diluted Rodinal produced very thin negatives, which can hardly be printed with grade 5 filter. The accepted wisdom among Minox circle at that time was the chemicals in Minox tank using higly diluted Rodinal was simply insufficient.

-- martin tai (martin.tai@capcanada.com), January 07, 1999.

Following the standard instruction, using highly diluted developer ( for example 1:100 Rodinal ) , agitation by using Minox thermometer indeed produces too thin negatives, this seems to prove that the chemicals in 55 cc of diluted developer may indeed not enough. To increase the volume of developer, stainless steel 9.5 mm Nikkor reel is often used to develop Techpan.

Is it true that the chemical in diluted develoepr contained in a Minox tank is not enough ?

Let us look at how people develop 35mm Techpan film. Many B&W photographers developed Techpan sucessfully with 1:100 Rodinal in 250 cc developing tanks.

The sensitized area of 35mm film is 24 x36 = 864 square mm; the sinsitized area of Minox frame is 8x11 = 88 mm. A roll of 36 exp 35mm film has a total area of 31,100 sq mm; a roll of 36 exp Minox film has total (sensitized ) area of 3168 sq mm, about only one tenth of that of 35mm film.

This fact indicates that the required amount of developer for a roll of Minox film is only 1/10 of that required for 35mm, that is 250/10 = 25 cc.

Minox tank has a capacity of 55 cc, more than two times of 25 cc. So the chemicals in Minox tank is not only enough for (1:100 ) , but more than enough.

-- martin tai (martin.tai@capcanada.com), January 07, 1999.

Five advantages of Minox daylight development tank vs SS reel

1) Extremely easy to use, no hand loading in darkroom or dark bag is needed. And loading film is a lot faster with Minox tank than SS reel.

2) Good results. Since handling is minimized, less chance for film emulsion to catch greease or dust.

3) Economy: It uses small amount of chemicals, hence quite cheap to operate.

4) Enviroment friendly. A roll of 36 exp B&W film uses only 1 cc or less concentrated developer.

5) Minox tank is cheaper and readily availabe than a 9.5 mm SS reel.

Minox photography without Minox tank is missing one third of fun of Minoxing.

Minox camera, Minox tank Minox enlarge are three foundation stones of Minox photography. Three marvelous designs of Walter Zapp.

Picture of miNox day light development tank

-- mt (cg081@torfree.net), January 07, 1999.



1) Turn the spiral film holder clockwise to unwind until it cannot go any further, at this point the spiral rests about two inches above the cap. Open the Minox development tank, Push the film clip spring to one side.

2) Open ONLY the supply side of the Minox cassette, by pinching the snap lock and lift off the cassette cap, be careful not to damage the cap or the cassette, as the cassetteis reuseable indefinitely, if you are careful. Pull out the remaining unexposed film lead from the supply side. You will see a hole on film lead

3) Sit the Minox cassette in the recess in Minox tank cover, There is only one way you can do this. Hook the film lead to the litte screw move back the film clip spring on top of the film for additional security.

4) Close the tank cover( with the spiral ). Wrap a piece of rubber band around the snout such that the cover will not be accidentally open while developing.

5) Turn the spiral GENTLY counter clockwise to lower the spiral into the tank, in doing so, the spiral automatically pulls out the film and winds it around the spiral, emulsion side outward, into the development tank. When you feel you cannot go any further,the film is loaded

For 15 exp film ,you may put the with filler ring in place.

Do not try to turn the spiral coil clockwise during development, as you might slacken the film, causing uneven deveolpment or trap air bubbles.

-- martin tai (martin.tai@capcanada.com), January 08, 1999.


Prepare 55 ml of your favorite developer with distilled water and pour it into the center well. When done, give it a few good tap with your palm, but don't knock the tank on table top or counter top trying to remove bubbles, you may crack the tank.

Use with care a Minox tank lasts for decades.


:Shake the tank to agitate. As long as you are consistent, these method all works with normal strength developer. Only when highly diluted developer such as 1:100 Rodinal or 1:80 Rodinal-Special is used, then it is necessary ot use recycle/replenish method.


Use Kodak fixer or any other fixer according to instruction.


Open the tank ,carefully unwind the film from the spiral, put it in a tray under slow flowing water tap to wash for about 20-30 minutes, or according to your favorite washing scheme.


Dip the washed negative in 200 cc distilled water with 5 drops of Kodak Photoflo added and stirred, for about one minute, than hang it up in a dust free room to dry. Weight the bottom end with a clip to keep film straight.

Don't squeeze film with fingers.

Do not use too much Fotoflo, it will left cruz on the negatives.


Thoroughly wash the tank, the cap and the spiral, air dry these parts in a clean place.


Wash all the parts of Minox cassette, then left them water for the same duration you wash the film, to clean out residue chemicals left on the cassette felt. Air dry the cassette throughly to prevent fungus.

-- martin tai (martin.tai@capcanada.com), January 08, 1999.

I use a Gerber 140 ml baby bottle to measure 60 ml or 80 ml distilled water, then use a baby medicine dropper to measure 1 cc Rodinal-Special and mix it in the Gerber bottle. Distilled water is important for preparing developer and fixer, it reduces the chance of dust and deposite on Minox negatives.

-- martin tai (martin.tai@capcanada.com), January 30, 1999.

According to Hubert Heckmann, late model of Minxo daylight developmemt tank has MINOX logo, old version had miNox mouse logo. My Minox tank bought a few years ago came in a red box with MINOX logo on the box, but with miNox mouse logo on the tank. I haven't seen a Minox tank with MINOX logo.

-- martin tai (martin.tai@capcanada.com), February 23, 1999.

Check MINOX tank for leak

When you buy a Minox daylight development tank, new or used, make sure you check it for any leakage. Fill the tank with water to the brim, wip it dry with paper towel, then put the tank filled with water on a piece of paper, leave it for 20 minutes. Check it for any leakage. Due to the labyrinth struture of the tank, it is not possible to detect leakage by simply looking at the tank against a light.

Check Minox tank for fit

Minox tanks made over the years may have slight variations in dimension. When buying used Minox tank, make sure to check whether the cap is too tight or too loose, as the cap may be from a another tank.

Spacer ring not from the same batch when put into the tank may jam and it is difficult to take it out.

-- martin tai (martin.tai@capcanada.com), April 03, 1999.

If you buy a used Minox tank sight unseen from the web, and if you find that the lid is very tight and not easy to lift off, it is a sure sign that this tank is not original, but put together from two broken tanks' parts.

Some problem of buying Minox tank sight unseen includes:

Unless you check out in person, otherwise you are much better off buying a new one, with warranty, instruction, thermometer and original box.

-- martin tai (martin.tai@capcanada.com), April 25, 1999.

A Development tank with Profound Philosophy

The Minox daylight development tank is a unique tank created by Walter Zapp. Unlike any other tank, it is a tank with a philosophy. Maxinum effect with mininum amount of developer. There is no other development tank has this philosopphy.

Ordinary development tank consist of a lid, a container and a film spiral.

Minox tank's central post was designed to greatly reduce the amount of developer needed.

Without this developer 'reducer' the tank would still be quite small. With it, however it clearly indicates its creator's strife for perfection, to be closest to law of nature.

Who cares ? some would said, developer is dirt cheap. That however is a different kind of philosophy, and has very little Minoxism in it.

-- martin tai (martin.tai@capcanada.com), September 10, 2000.

Minox GmbH has discontinued the daylight development tank

-- martin tai (martin.tai@sympatico.ca), January 12, 2002.

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