Unusual Accessories for the Pentacon Six
by TRA

The FAN-1 lens converter


[fan1crp_s]


The Fan-1 is supplied by the manufacturer in a light-weight cardboard box that is not quite strong enough to take the weight of the accessory.  (Note the crumpled state of the thin carboard.)

 

The top of the box states:

[fanbxtop]

For those with limited Russian, a translation into English is on the side:

[fan_eng]

The cover of the accompanying manual states:

  [fan_covr]
from which we see that it is a 0.6ื afocal converter for the front of a lens.  In other words, it reduces the focal length to 60% of the designed focal length of the lens with which it is used, so an 80mm lens has an effective focal length of 48mm and becomes a wide-angle lens.

One side of the box shows the effect:


[fan_difce]

(Note that the Russian captions state "With FAN-1" and "Without FAN-1".
The English-language vocabulary of the person charged with translating this into English cannot have been this extensive, as "With" becomes "Yes" and "Without" becomes "No".  However, we might even have understood the meaning of the picture without any text!)

The square image in the illustration is a pointer to the use for which the Fan-1 was designed: to cover the 6ื6 (2ผ” square) film format.  The specification states that it should be used with an 80mm lens:

 
[fan_spec]
(It is unfortunate that the quality of the printing of the manual was not up to the standard of the accessory that it accompanied, and some of the pages are printed crooked!)


The specification also tells us that the front of the Fan-1 takes filters with 93mm diameter and 0.75 pitch.


The resolution chart in the manual reveals that the lens with which the Fan-1 was designed to be used was the 80mm Ukrainian Volna-3B, which was supplied as the standard lens with the Kiev 60 camera.
 
[fan_res]
The lines-per-millimetre chart claims that from f.4.5 (the half stop between f/4 and f/5.6) on down, the loss of resolution compared with using the Volna on its own is minimal.


The manual indicates that mounts were available (or at least, envisaged) for lenses with front filter threads of 52, 55, 58, 62 and 67mm and in the Rolleiflex bayonet:

[fan_mnts]
This covers various standard lenses with the Pentacon Six mount: the 80mm Biometar (58mm), the Volna-3B (62mm) and the various 80mm lenses for the Exakta 66 (67mm).


The manual also suggests using the Fan-1 on a slide projector or an enlarger.
 
[fan_proj]
Perhaps this is where the 52mm and 55mm mounts will be useful.  I have not been able to test this option, which would enable one to project a larger image, or print a larger one – always assuming that the column of the enlarger was not in the way!



The Fan-1 that I received came with front and rear caps.  No lens hood or shade was supplied.


[fan_01]


It also had the 52mm and 62mm mounts


[fan_02]

An internet search did not bring up any information on this accessory, so – in order to use it on the Biometar lens – I bought a 58mm-62mm step-up ring.  Naturally, that moves the Fan-1 slightly further forward than if the manufacturer's 58mm ring were available, which would of course be used on its own.  However, the step-up ring is slim, and exact distances with front-of-lens accessories are generally not critical.  As the FAN-1 was designed for use with various lenses, this does indeed appear to be the case.

A slight inconvenience: when I leave the 58-62mm step-up ring on the back of the 62mm mount, the rear lens cap falls off.

As the combination of the Fan-1 and an 80mm lens results in an effective focal length of 48mm, the obvious lens with which to compare it is the 50mm Carl Zeiss Flektogon.  It could of course also be compared with either of the 45mm Arsenal or Arsat lenses, the common Mir-26B and the rare Mir-69B.  According to the specification, it is fractionally less wide than the two Mir lenses.


Here the Fan-1 is on an 80mm Biometar
[fan_03]


To give an idea of size, here it is on the Biometar (on the right), with a 50mm Flektogon beside it (on the left).


Note that the FAN-1 appears to be finished with a coat of black paint, which is coming off where the front lens cap rubs against the edge.
[fan_06]

While the combination of Biometar and Fan-1 is larger than the Flektogon, the total size and weight is less than taking both the Biometar and the Flektogon on a photographic outing.



Finally, here is what the Fan-1 looks like on a Pentacon Six.  Again, the Flektogon is on the left.The Fan-1 that I received came with front and rear caps.  No lens hood or shade was supplied.


[fan_07]


 

Test results

 

All the following images were shot on my “usual” Pentacon Six TL, with Fuji PRO160NS negative film.  The lenses were set at f/8 and the exposure was 1/500.  A tripod was used and the images were scanned with an Epson Perfection 750 PRO at 6400 dpi using VueScan software.


Coverage (angle of view)

The FAN-1 does genuinely seem to give the angle of view advertised, and the coverage is a tiny bit wider than with the 50mm Flektogon


80mm Biometar on its own
[C532-16s]
50mm Flektogon
[C532-13s]
80mm Biometar + FAN-1
[C532-14-15s]

Is there any vignetting (darkening of the corners of the image)?  In a word: none.  This is a pleasant surprise.

 

Colour balance and contrast

When the FAN-1 is used, there is an extremely tiny colour cast, compared with the 80mm Biometar lens on its own, with the image taken with the FAN-1 having a hint more pink.  No difference of contrast is distinguishable.  So far, very good.

 

Resolution
There is a very slight loss of resolution in the centre of the image, compared with the Biometar on its own, or compared with the 50mm Flektogon, and a tiny hint of chromatic aberrations (colour fringeing) – see brickwork to left of ground floor window.



80mm Biometar on its own
[C532-16lw]
50mm Flektogon
[C532-13lw]
80mm Biometar + FAN-1
[C532-14-15lw]

As is usual on this website, I have made the tests extremely demanding, and these differences are so minor that they would not be visible at normal degrees of enlargement of the whole image.

Further away from the centre, the loss of resolution is greater, with the Biometar (on its own) giving the best result, the 50mm Flektogon coming in behind it, and the FAN with the Biometar behind the Flektogon.  Look at the burglar alarm:


80mm Biometar on its own
[C532-16ba]
50mm Flektogon
[C532-13ba]
80mm Biometar + FAN-1
[C532-14-15ba]

However, if you look back to the images of the whole of the frame, you will see how tiny the burglar alarm is within the image, so in fact in all three pictures the results are extremely good.  We are here magnifying a tiny portion of the image massively.  The result with the Biometar on its own is indeed outstanding.


At the edge of the frame, the resolution is, unsurprisingly, marginally poorer still.  See garage roof tiles and trees.



80mm Biometar on its own
[C532-16grt]
50mm Flektogon
[C532-13grt]
80mm Biometar + FAN-1
[C532-14-15grt]

Again, however, the resolution even here is remarkably good.  The depth of field (the area of sharp focus) decreases as the focal length used increases, and it would appear that in the case of the 80mm Biometar, the garage roof and the trees behind it were beyond the area covered by the depth of field, so the lack of sharpness here does not indicate a lens defect.  I normally shoot at f/11, but for these pictures I used f/8.  For architecture (and, indeed, many landscape shots, too!), f/16 would be preferable.  Using that smaller aperture would have increased the depth of field and would probably have brought the garage roof and the trees into focus.

Colour fringeing is also much more obvious near the edges of the image frame – see the top, left-hand window frame and fascia.



50mm Flektogon
[C532-13lhw]
80mm Biometar + FAN-1
[C532-14-15lhw]


80mm Biometar on its own
[C532-16lhw]		 The top, left-hand window is not visible in image taken by the Biometar on its own.  Here, for comparison, is the far left-hand edge of the Biometar image of a ground-floor window.  It is at the boundaries of the white window frame that any colour fringeing will be most easily seen, if it is there.  With the Biometar, there isn't any!

Distortion

Straight lines are rendered straight with the Biometar, and also with the Flektogon.

However, the FAN-1 introduces significant barrel distortion.  This is a common problem with wide-angle lenses, but it is still disappointing.  We do of course realise that these days barrel distortion can be reduced, and possibly even eliminated, with software, but the purpose of the test is to see what this lens produces.
[C532-13kb]  Flektogon



[C532-14-15kb] FAN-1
The row of light-grey kerbstones between the two sets of slightly-pink blockwork of the pavement and the road is in reality virtually straight, and appears straight in real life from this angle.  The difference between the Flektogon and the FAN-1 is obvious!

In real life, the house also does not have the shape of a puffed-up balloon.


[C532-13rf] Flektogon



[C532-14-15rf] FAN-1

For images that include architecture, as in this test, or with other significant straight lines, I think that I would avoid using the FAN-1.  If I wanted to travel light out into the countryside, I might put it in my bag instead of taking the 50mm Flektogon or 45mm Mir-26B.  However, I would be more likely to take the small 45mm Mir-69!  (See here -- scroll down)


Footnote

Out of curiosity, I shot the same image with a 65mm Flektogon (zebra style).  Given the criticism of this lens that is sometimes encountered, I was extremely pleased with the results:
No colour fringeing, no distortion, but high resolution and high contrast.

[C532-17]  65mm Flektogon

The lens here had a slim-line UV filter fitted, on front of which was the CZ lens shade that was designed for this lens (but which is often sold with the claim that it is for the 50mm Flektogon!).

There is slight vignetting in the corners and I wonder if this has been caused by putting the lens shade on the front of the filter.  For more on lens shades, see here.

For more on the 65mm Flektogon, see here.

To go back to the main page on teleconverters, click here.

To go back to the beginning of the lens tests, click below and then choose the focal length that you want to read about.

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ฉ TRA July 2015  Latest revision: January 2016