MARCH COLUMN: Minox Enlargement

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There are all kinds of opinions about the enlargeability of Minox 8x11 negatives. People who never use Minox thinks Minox is a toy, cannot enlarge beyond 4x6, but in fact many expert Minoxers enlarge their 8mm x 11mm size negatives to 16x20", some even to garage door size mural. What is the criteria of enlargebility ? What are the main factors in obtaining big enlargement from Minox which looks sharp ? Is film a limiting factor ? Is lens a limiting factor ?

-- martin tai (martin.tai@capcanada.com), March 01, 1999

Answers

WHAT IS ON FILM RESOLUTION

On film resolution is the combined result of resolution of lens and resolution of film, the relations is given approximately by

On film resolution = 1( 1/(lens resolution) + 1/(film resolution) ) or symbolically by the convolution operator # :

On film resolution = (lens resolution) # (film resolution) )

For example if lens resolution = 300 lpmm, film resolution = 300 lpmm on film resolution = 300 # 300 = 150 lpmm

When a negative is enlarged, the on negative resolution is convolved with the enlarging lens

On paper resolution = (negative resolution) # (enlarger lens resolution)

If I know the resolution of the camera lens, the film and the enlarger lens I can calculate the resulting resolution coming out from the enlarger; I divide this number by 4 to get the maximum allowable enlargement for close watching.

-- martin tai (martin.tai@capcanada.com), March 01, 1999.

CASE STUDIES

In the following case studies

A typical convolution equation reads

MINOX(330) # TP(320) = 162 lpmm # MINOX(330) = 109 lpmm -> 27x -> 9 x 12 in

Meaning : Technical pan film with 320 lpmm resolution taken with Minox subminiature camera yields 162 lpmm on film; which in turns convolved with a Minox enlarger lens with resolution of 330 lpmm yields 109 lpmm, which is adequate for 109/4 = 27 times enlargement, corresponding to a 9x12".

In the following four cases, I analysis separately the effect of the film, the lens, and the combined effect of film and lens on enlargement

-- martin tai (martin.tai@capcanada.com), March 01, 1999.

CASE 1: AGFAPAN 25 NEGATIVE WITH DIFFERENT ENLARGING LENS

CAMERA FILM ON FILM ENLARGER RESOLUTION MAG SIZE
MINOX(330) APX(150) 103 lpmm 35MM(140) 59 lpmm 15x 5 x 7 in
MINOX(330) APX(150) 103 lpmm MINOX(330) 79 lpmm 20x 6 x 9 in





APX25 here is a proxy for a range of medium resolution film, including Agfapan APX 25, Ilford Delta 100, Ilford Pan F+ etc.

When using medium resolution film, even with Minox enlarger, the maximum size of sharp enlargement is about 6x8". Going any higher, you will not be able to get 4 lines/mm on print, and the film will be fuzzy

If you like to use only medium resolution films such as APX25, Minopan 100 and the like there is not much gain in switching from a 35mm enlarger to Minox enlarger, as the improvement is not great.

CASE 2: NEGATIVES FROM DIFFERENT FILMS ENLARGED WITH 35MM(140) ENLARGING LENS

CAMERA FILM ON FILM ENLARGER RESOLUTION MAG SIZE
MINOX(330) APX(150) 103 lpmm 35MM(140) 59 lpmm 15x 5 x 7 in
MINOX(330) TP (320) 162 lpmm 35MM(140) 75 lpmm 19x 6 x 8 in
MINOX(330) SHR(800) 234 lpmm 35MM(140) 88 lpmm 22x 7 x 10 in

Clearly, if you use 35mm enlarger to enlarge Minox 9.5mm negative there is no much point is switching to high resolution copy film, because, even with Fuji Super HR film with 800 lpmm, you can't get bigger enlargement than 7x10""

-- martin tai (martin.tai@capcanada.com), March 01, 1999.

CASE 3: TECHPAN FILM WITH DIFFERENT ENLARGING LENS

CAMERA FILM ON FILM ENLARGER RESOLUTION MAG SIZES
MINOX(330) TP (320) 162 lpmm 35MM(140) 75 lpmm 19x- 6 x 8 in
MINOX(330) TP (320) 162 lpmm MINOX(330) 109 lpmm 27x 9 x 12 in



When medium high resolution film such as Kodak Technical Pan film is used there is significant improvement by switching from 35mm enlarger to Minox enlarger: because, with Minox enlarger, you may be able to get sharp 9x12" enlargement, while with 35mm enlarger, you are limited to 6x9" .

CASE 4: MAX SIZE OF ENLARGEMENT FOR DIFFERENT FILMS WITH MINOX ENLARGER


CAMERA FILM ON FILM ENLARGER RESOLUTION MAGINICATION SIZE
MINOX(330) FP4(110) 103 lpmm MINOX(330) 66 lpmm 17x 5 x 7 in
MINOX(330) APX(150) 103 lpmm MINOX(330) 79 lpmm 20x 6 x 9 in
MINOX(330) TP (320) 162 lpmm MINOX(330) 109 lpmm 27x 9 x 12 in
MINOX(330) HSU(500) 199 lpmm MINOX(330) 124 lpmm 31x 10 x 14 in
MINOX(330) SHR(800) 234 lpmm MINOX(330) 137 lpmm 34x 11 x 15 in

With Minox enlarger, the resolution of the film has great impact on quality of enlargement; the higher the resolution the bigger enlargement can be made. With FP4 film, the biggest you can get is 5x7", with Techpan, you may be able to get sharp 9x12", with Fuji Super HR, sharp 11x15" is possible.

-- martin tai (martin.tai@capcanada.com), March 01, 1999.

CONCLUSION

A) If you use low resolution films(under 120 lpmm) such as Minopan 100, Agfapan 100, Ilford Delta 100, Tmax 100 etc, there is not much advantage in using Minox enlarger

B) If you use 35mm enlarger, there is not much advantage is using very high resolution copy film.

C) If you want big enlargements, which can be looked at up close, you must use high resolution film in your Minox camera and use Minox enlarger to enlarge the negative. With 800 lpmm film and Minox enlarger, the maximum size of sharp enlargement can be 11x15"

D) You need ultra high resolution film of 5000 lpmm, and with Minox enlarger to get 15x 21" enlargement

E) 16x20", 20x30" or mural is still possible from Minox TP or SHR negatives but the viewing distance must be proportionally increased from 10"

For TP negative taken with camera, enlarged with Minox enlarger:

For Fuji Super HR negative from Minox camera, enlarged with Minox enlarger:



-- martin tai (martin.tai@capcanada.com), March 01, 1999.
Case 5:

Medium-format [6x6] lens (90) # APX(150) # enlarging lens (100) = 36 lp/mm -> 9X -> 20 X 20 in Not alot bigger than Minox, but APX 25 is a much easier to use film than TP, HSU and SHR.

-- The Pragmatist (prag@realworld.com), March 02, 1999.

I can load up Agfapan APX 25 in Minox and travel the world, I don't think I can bring EI 25 film for MF for same purpose. I can walk on the street, at sunny day I use 1/250 shutter speed to capture people walking and passing cars on street with great depth of field. To achieve the same degree of depth, a Hassy with 80/2.8 Planar need to stop down to F16; with EI 25 film, what can you do with F16? you can only use 1/15 sec; the pedestrians and cars in your 6x6 pictures will be blurry, if you increase your shutter speed to F3.5, and use 1/250 sec, then you will have very shallow depth of field, in both cases, you pictures when blow up to 8x10" will not look as sharp as pictures from Minox with same Agfa APX 25 film. One cdistinct characteristic of Minox is great depth of field in small package.

-- martin tai (martin.tai@capcanada.com), March 04, 1999.

MINOX VS MF

Can Minox prints look as good as MF prints ?

It all depends !

A) If you have microscopic eyesight and able to see incredible fine detail, then you don't need enlargement, and you will see Minox slide is far sharper than MF contact prints.

B) At 8x10" Minox enlargements may APPEAR to look as good as an 8x10" from MF.

Let us take example of TP negative from Minox, using Minox enlarger the projected image has a resolution of 109 lpmm. Enlarge to 8x10" is 25x enlargement, the on print resolution is 109/25 = 4.4 lpmm

According to Pragmatist's calculation, Agfapan APX 25 taken with MF lens and enlarged with MF enlarger lens, has a projected resolution of 36 lpmm. 8x10" from 6x6 is 3.3x enlargement. The on print resolution is 36/3.3 =11 lpmm.

You will hardly see any difference from this two prints. The 8x10" from MF has much higher resolution, but you cannot see the finer details, all you can see are the details with resolution of 4 lpmm or less, just like the 8x10" from Minox.

C) Minox TP negative enlarged to 12x16" = 36x enlargement, on print resolution = 109/36 = 3 lpmm. The Minox enlargement starts to break down, unless you watch from distance further away then 10".

MF APX 25 negative enlarge to 12x16" = 5 x enlargement, on print resolution 36/5 = 7 lpmm. Obviously beyond 8x10" MF enlargement looks much better than the the one from Minox.

-- martin tai (martin.tai@capcanada.com), March 04, 1999.

I can load Tmax 400 in my 6x6 camera and travel the world. 6x6 lens (90) # TMY (80) # enlarging lens (100) = 30 lp/mm -> 7.5X -> 16x16 in. A print with 7 lp/mm looks sharper than one with 4 lp/mm For ultimate sharpness one should use a tripod. A minox on a tripod looks silly. Large DOF isn't everything. Such photos often look cluttered and busy to me. Can you get very narrow DOF with a Minox? I can go either way with my 6x6. I carry a Leica M if I really want to travel light.

-- The Pragmatist (prag@realworld.com), March 05, 1999.
Prag with your EI 400 film and a 6x6, you indeed can do exactly what I can do with EI 25 film in Minox, such as freeze cars, pedestrians and have similiar DOF; no doublt, you can get nice 16x16", but I can get nice 9x12" from EI 25 Techpan. 16x16" is about 2.5 times in terms of square inches of picture vs 9x12" from Minox; but a Hassy with 80/2.8 Planar weights more than 1500 g, a Minox TLX weights only 98 g. For Minox, it is oone gram per square inch of picture vs 6 grams per square inch of picture from MF. Minox is a very efficient camera.

-- martin tai (martin.tai@capcanada.com), March 05, 1999.
"a Hassy with 80/2.8 Planar weights more than 1500 g, a Minox TLX weights only 98 g." It's not fair to compare an SLR with a remoovable back to a rangefinder Minox. The Mamiya 6 would make a better comparison.

-- The Pragmatist (prag@realworld.com), March 06, 1999.
Interesting properties of convolution operator # 1) A # B # C = (A # B) # C. ie, there is no need to calculate the on film resolution first, then # it with enlarging lens. 2) A # B # C = C # B # A. Meaning, camera lens, film, and enlarger lens plays identically imporant roles. The idea that enlargement has nothing to do with enlarging lens is a myth. Interestly, 2) indicates that cut out a 8x11 piece of 35mm film taken with 35mm enlarger, enlarge it with Minox enlarger is identical to enlarge a Minox negative in a 35mm enlarger !

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