Minox 8x11 lens resolution

How to test Minox lens

Resolution of COMPLAN, MINOX, MINOXAR

<h2> Resolution of COMPLAN /MINOX LENS </H2><P>Photographing a next neigbour's wall or a car parked on the street many be conveniet, but is not a proper way to test lens resolution. Using eye ball to test lenes is like weighting chicken with bare hands<p>Resolution figure is not popular with analog cameras. But now resolution figures show shows up in all sorts of scanners and digital cameras.<p><h3>Lens Test Chart </h3>

Test chart with graduated target from 15 lpmm to 100 lpmm continues bar pattern and other test diagrams is necessary for meaningful test <p>.

Chasseur d'Image Mire Test chart is an exellent test chart.

<p>

<center><img src="http://www.accessv.com/~martntai/public_html/manual/CI.JPG"border=7> Chasseur d'Image ISO Lens

test chart </center><p>

<P> You may download USAF chart from photo.net<p>

<p><a href="http://www.photo.net/photo/optics/USAF1951.ps">USAF chart </a><p>

When I tested Minox GT-E, the film plane to test chart distance = 50 x focal length or 50 x 35mm = 175 cm, AGFA HDC 100 color print film ( the film I use regularly for GT-E );<P> for Minox B/C, I set the film plane to test target distance beyond 50x focal length, because

the resolution of Minox 8x11 lenses are well over the limit of Chasseur D'Image chart (or any other charts) at 50x focal length.<p>

The film to chart disttance was chosen as 133 cm ( middle point between 1 meter and 2 meter ) on my metric Minox scale (For middle point values of Minox focusing scale, see <a href="http://www.greenspun.com/bboard/admin-q-and-a-fetch-msg.tcl?msg_id=000N1Z">related thread</a>)<p>

Kodak Techical Pan film (my stardard film for Minox subminature cameras ), developed in 1:80 Rodinal Special.

<H1><font color ="red"> Minox 8x11 Camera lens test</H1></font>

<font color="green"> <P> I recently testedthe resolution of Minox lenses <P> Test Chart: Mire-test Chasseur d'images <P>Film:Kodak Techical Pan 4.5 milEstar-AH base 150' roll

slitted into9.5mm Minox film. <P>Developer:Agfa fine grain BW developer Rodinal-Special 1:80 dilution, 15 minutes 20 degree C. <p>Microscope:Olympus microscope 10x objective, 10x eyepiece.

<p>The follwoing are the resolution figures. <p> Minox C , "MINOX" lens15mm/f3.5 163 line-pair/mm on film. <p> Minox B,"COMPLAN" lens, 15mm/f3.5 177 line-pair/mm on film <p>Note: MINOX lens is the

lens in C, LX, TLX, and Minox enlarger III. <p>COMPLAN lens also for: III, IIIs, B and Minox enlarger II <p> COMPLAN hasa very slightly curved film plane.

<p> Base on 320 lpmm resolution of Techpan, the aerial resolution ofMinox lens is estimated atabout 360 lpmm average

<p> If higher resolution film is used, the on film lpmm will certainly goes up.</font>

COMPLAN and Minox lenses are the sharpest general purpose photographic lenses. No 35mm or MF lens approaches the sharpness of these lenses.

For example, Canon EF USM 50mm f1.4 lens has a top resolution about 80 lpmm, a Nikkor S-AF 50mm/1.4 has top resolution of 64 lpmm.

Of course, 35mm lens has the advantage of bigger format.

Precisely of the superb sharpness of COMPLAN and MINOX, good 8x10" enlargement is not only possible,

there are many Minox experts around the world regularly enlarge Minox pictures to 16x20".

( I have'nt reach that level yet ). Dr. William White claimed in his book that there were even Minox murals.

"The lens resolving potential of ultra-miniature cameras is illustrated by

the performance of the 4-element lens of the Minox. A test pattern the size

of the Minox negative image is projected through each lens to a screen

size of approximately 4x5 1/2 feet. Any lens which does not project this

pattern sharply from edge to edge is rejected. "

Joseph D. Cooper: the new ULTRA-miniature photography" Universal Photo Books.

Dr. Whilliam White claimed in "Subminature Photography" that

COMPLAN lens is sharper. My sharpest picture came from COMPLAN of Minox B, other Minox IIIs users have similar experience.

My lens test showed that COMPLAN is indeed slightly sharper.

However, COMPLAN lens has a curved film plane and curved presure plate, which seems to cause more

scratch across negative, MINOX lens with its flat presure plate seems

seldom cuases scratches, for that reason I prefer MINOX lens. Optically, uneless I am really really focus very acurately, ie mount the camera on tripod,

measure the object disttance with a measuring tape, and even bracket the distances then compare under a microscope, otherwise

there is really no visible difference.

Minox literature proclaims the lens for the new Minox ECX to be the

sharpest lens in serial production!

<p>

How does it compare to the Complan or Minox lens?

The MINAR lens on ECX is new design by Leica, from what I heard, it is sharper then previous design.

It is quite possible the MINOX has quietly put the new lens in latest

MINOX CLX and TLX. But IMO, unless you use ultra fine grain film such as Fuju Super HR, and enlarge it to 11x14 with good enlarging lens,

or perform a lens test using test chart and view under microscope, it is hard to notice difference

with naked eyes.

<h3>Examaple of high resolving power of COMPLAN LENS</h3>

<center> Original size

<img src="http://www.accessv.com/~martntai/public_html/manual/stlawr.jpg"><P>

Enlarged to 3.5x5"<p><img src="http://www.accessv.com/~martntai/public_html/manual/STLAWREN.JPG">

<p>2 cm from bottom right corner is a sign post, which has a street sign, only 0.1mm on film

1.5mm on print.

<p> Enlarged 200x <p><img src="http://www.accessv.com/~martntai/public_html/manual/one.jpg">

<p> Each character is only 0.02 mm width. A typed page can be packed in to 1.5x 2mm on film. With the 720 lpmm film from http://www.gigabitfilm.de, or 600 lpmm Agfa Copex Rapid, higher resolution is possible

<h3> Performance Index of Minox </h3><p>

</center>

Performance index = lpmm x format dimension divided by camera weight

in g

<pre>

The following is a few examples

CAMERA lpmm format length weight performance per g

Minox TLX 170 11 98 17

M6+50 'LUX 95 36 835 4

Hassy 503cx 75 56 1520 3

</pre>

Minox TLX not only has the sharpest photographic lens, but also

has by far the highest performance index of 17 vs only 4 of Leica

of M6

<h3>Lens scaling down to 1/3 increases resolution by 3x </h3>

<pre>

A typical 45mm f 3.5 four element three group tessar lens of the following construction

35mm LENS DATA

Tessar 45mm 1:3.5

SRF RADIUS THICKNESS APERTURE RADIUS GLASS

1 14.459176 V 2.070000 12.838432 SK7 C

2 4.5044e+08 V 2.427203 8.320786 S AIR

3 -32.012000 V 1.576546 6.065012 S LF7 C

4 12.972718 V 2.802544 5.243782 AS AIR

5 4.5044e+05 V 0.920000 7.228976 S KF9 C

6 12.860000 V 4.000000 7.656752 S SK10 C

7 -21.260844 V 38.311861 9.256876 S AIR

with Schottky crown glass SK7, SK10 and flint glass LFY, KF9:

*REFRACTIVE INDICES

SRF GLASS RN1 RN2 RN3 VNBR TCE

1 SK7 1.607290 1.614397 1.604183 59.458386 64.000000

2 AIR 1.000000 1.000000 1.000000 -- 236.000000

3 LF7 1.575011 1.584763 1.570904 41.490126 79.000000

4 AIR 1.000000 1.000000 1.000000 -- 236.000000

5 KF9 1.523412 1.530515 1.520350 51.492205 68.000000

6 SK10 1.622801 1.630432 1.619487 56.902918 70.000000

7 AIR 1.000000 1.000000 1.000000 -- 236.000000

*PARAXIAL CONSTANTS

Effective focal length: 44.922959

Working F-number: 3.500000

Petzval radius: -128.830104

*CHROMATIC ABERRATIONS

SRF PAC SAC PLC SLC

SUM -0.024337 -0.014522 -0.006531 -0.004691

*SEIDEL ABERRATIONS

SRF SA3 CMA3 AST3 PTZ3 DIS3

SUM -0.120322 0.018948 0.079036 -0.313855 -0.195976

*FIFTH-ORDER ABERRATIONS

SRF SA5 CMA5 AST5 PTZ5 DIS5 SA7

SUM 0.075191 -0.022712 -0.001510 0.232300 -0.058335 0.034253

*SPOT SIZES

GEO RMS Y GEO RMS X GEO RMS R DIFFR LIMIT

0.007877 0.007877 0.011139 0.002501

***********************************************************

The same lens construction with same glass types if scaled to 15mm, it becomes

SUBMINIATURE LENS DATA

Tessar 15mm 1:3.5

SRF RADIUS THICKNESS APERTURE RADIUS GLASS

1 4.827991 V 0.691183 2.300000 SK7 C

2 1.5040e+08 V 0.810455 2.300000 AIR

3 -10.688966 V 0.526416 2.300000 LF7 C

4 4.331655 V 0.935783 2.300000 AIR

5 1.5040e+05 V 0.307193 2.300000 KF9 C

6 4.294018 V 1.335620 2.300000 SK10 C

7 -7.099102 V 12.792521 2.300000 AIR

*PARAXIAL CONSTANTS

Effective focal length: 15.000000

Working F-number: 3.500000

Petzval radius: -43.017014

*CHROMATIC ABERRATIONS

SRF PAC SAC PLC SLC

SUM -0.008126 -0.004849 -0.002181 -0.001566

*SEIDEL ABERRATIONS

SRF SA3 CMA3 AST3 PTZ3 DIS3

SUM -0.040176 0.006327 0.026391 -0.104798 -0.065437

*FIFTH-ORDER ABERRATIONS

SRF SA5 CMA5 AST5 PTZ5 DIS5 SA7

SUM 0.025107 -0.007584 -0.000504 0.077566 -0.019478 0.011437

*SPOT SIZES

GEO RMS Y GEO RMS X GEO RMS R DIFFR LIMIT CENTY CENTX

0.002630 0.002630 0.003719 0.002501 -- --

Conclusion

1) The blur spot size of 15mm Tessar 0.003719mm is 1/3 of 45mm tessar 0.011139mm

2) The resolution of 15mm Tessar 268 lpmm is three time of 45mm Tessar, 89 lpmm

3) Chromatic, Seidel (3rd order) and 5th order abberations of 15mm Tessar is one

third of corresponding 45mm Tessar

All these are the advantage of scaling down.

However, scaling down has one disadvantage, it increases the field curvature of

the scaled down lens by a factor of 3. From a Petzval radius of -129 mm to

-43 mm.

All these explains why COMPLAN lens is much sharper then 35mm lens, and why COMPLAN needs a curved film plane

</pre>

According to Minox Friend , the MINAR 15mm f/5.6 lens on Minox EC

has a resolution figure of 200 line pair/mm<p>

<img src="http://www.submin.com/8x11/manuals/minox/club/minox_freund/friend_9802_05.jpg"> Minox Friend 98</a>