The Chinese Biotar: Haiou-64 海鸥 58mm f/2 (SR)

Is the Chinese Biotar any good?

Disassembly and Cleaning


Hai’ou (accent mark to aid pronunciation, sounds like Hai O), 海鸥 in Chinese, means seagull.  And there is a seagull symbol on the name plate.  This is one of several Chinese camera brands available during the pre-economic reformed days in China. Today we have many more Chinese lenses, like the now famous 7Artisan 50mm f/1.1 in Leica M mount.  But back in those days, the Seagull brand was one of the few that existed, and exported in limited quantities.  I had seen a few Seagull cameras and lenses in my youth, not many though, as they were thought to be of poor quality.  Back then everyone had a Yashica Electro 35 GSN or some variant of that.

180511_001_Seagull DF 26262112A dead Seagull (1966), said to be a Minolta SR-2 clone.  The Chinese inscription is 海鸥 written in calligraphic style.  The original camera was said to be called Shanghai Model 7 in 1964, renamed to Seagull DF in 1967.  DF = Dan Fan 单反 (Chinese) = SLR (English).

The Chinese Biotar

The Carl Zeiss Jena Biotar 2/58 is a classic lens design that dates back all the way to the 1920’s. It is famous for its sharpness and unique bokeh.  The Biotar was developed by the famous lens designer Dr. Willy Walter Merté for Carl Zeiss and is a six element lens with asymmetrical outer elements, a variant of the Double Gauss design for higher performance and increased field correction and speed (Cheyenne Morrison).

58f2 Biotar

Optical formula of the Biotar 58mm f/2, 6 elements in 4 groups

Probably the most famous, cheap and readily available 58mm f/2 Biotar is a Soviet/Russian copy – the Helios-44 in its various guises (44, 44-2, 44-M, for example).  That would be a story for another day.

The Haiou-64 58mm f/2 is thus a copy of a copy – the Russian Helios 44 being a copy of the German Zeiss Biotar, and the Chinese copied the Russians. The Biotar type lens is said to be very good, this would be an interesting lens to play with.  From the look of it, this lens has mono-coating and should flare like mad, so the use of a hood is probably mandatory.

It seems the 64 in the name of the lens signifies that the design is of 6 elements in 4 groups.

Why not Minolta?

Chinese web sources reported that the Shanghai Camera Factory in 1964 made the Shanghai DF based on Minolta SR-1.  And in 1966, it made the Seagull DF based on Minolta SR-2 (Reference in Chinese).  There was no mention of Minolta’s assistance on the early Seagull cameras and lenses.  The later DF-300 (based on the Minolta X-300), however, was the product of Minolta-China cooperation.

DF-300 Licensed by Minolta.jpgDF-300 – licensed by Minolta (photo: Raymond Mok)

So I have a question: the Chinese copied the Minolta cameras (SR-1 and SR-2), including the lens mount (SR mount), then why not copy the Minolta Auto-Rokkor 55mm f/1.8 or other similar Auto-Rokkor normal lens?

My friend Henrik Robeck postulated the Zeiss Biotar is much older, with patents lapsed, and as all German patents became null and void after WW2 it was thus easy to copy.  Adding that the type of optical glass was also easier to produce as both the type of optical glass was known and copied (the Russians got the whole glass works) made it easier for the Chinese back then.  Anders Lattermann added that it was well known that the Chinese and the Soviet were cooperating well at that time and probably offered a way to get Soviet lens designs, tools and knowledge.

I also postulate that there was a conscious decision not to copy Soviet SLR cameras (the Zenit and Zorki, for example), but to copy Japanese SLR cameras.

Note on the lens mount

The Minolta manual focus lens mount is frequently referred to as the MC/MD mount on the net.  Strictly speaking, the lens mount is SR, while the MC is the designation of the lens type.  And from functionality there are 4 lens types: Rokkor, Auto Rokkor, MC Rokkor and MD Rokkor.  Rokkor lenses are preset type, Auto Rokkor lenses have automatic diaphragm, MC Rokkor lenses are with meter coupling (required for SR-T camera onwards) and MD Rokkor lenses allow for shutter priority and program modes (required for XD and X-700).

This Seagull-64 would belong to the Auto Rokkor type.

See for the complete listing of the Minolta manual focus lenses; scroll to the later part of the page and find a wealth of information on the various types and sub-types of Minolta SR lenses.  For example, the last Minolta manual focus lenses were simply MD lenses, the Rokkor designation was dropped.

Other Chinese Lenses

I did a search on the internet.  Chinese webpages were overall a rather disappointing experience.  Not much more than brief mentions of cameras without talking about lenses, and lots of nationalistic ranting.

There was, on MFLenses forum, a rather impressive chart:

Chinese SLR lenses

I was quite disappointed that on the usual ebay, Taobao (淘宝) not much else turned out on Chinese lenses.  Almost nothing except the Haiou-64 that could be counted vintage.  Notable ones (in SR/MC/MD mount) are:

  • Chrome-nosed Haiou-64 (Auto Rokkor type, subject of this write-up)
  • Black-nosed Haiou-64 (Auto Rokkor type, rubber grip)
  • Seagull 24mm f/2.8 (MD, rather rare)
  • Seagull-710 50mm f/1.4 (MD)
  • Seagull-610 50mm f/1.8 (MD), of significant plastic construction
  • Seagull 28-70mm f/3.5-4.5, that looks like a Cosina (MD)

Attempt to locate any of those in the chart above was proving futile.  Perhaps another trip to Shanghai Starlight Photographic City would be required to find more Haiou lenses.

My friend Raymond Mok has graciously provided photographs of the Seagull 24mm f/2.8 and Seagull-610 50mm f/1.8 (and the above DF-300 film back).

Seagull 24f2.8_1

Seagull 24mm f/2.8 (Photo: Raymond Mok)

Seagull 24f2.8_2

Seagull 24mm f/2.8 (Photo: Raymond Mok)


Seagull-610 50mm f/1.8 (Photo: Raymond Mok)

The lens

This is my first Chinese lens, not counting those modern Nikkors that are made in China.  My first encounter of this lens was in Inner Mongolia, in 2017 at 塞上老街and a copy of this lens along with a Seagull camera was offered to me at around $30.  Too much, as the lens had lost its rubber on the FR (clearly a newer version of this lens), and the camera was barely functioning.  I was also looking for one in Shanghai Starlight Photographic City 星光摄影器材城 at Luban Lu 鲁班路 in 2018.  Again prices were not to my liking.

I finally got this lens as part of a relatively large estate acquisition in May 2019, mounted on a (dead) Minolta XE-7.

The lens was in relatively poor shape when it arrived – rough focusing action, iffy aperture stop-down, and fungus.  The rough focusing action and fungus were solved quickly, the iffy aperture stop-down was not be fully resolved – for modern mirrorless use it was not necessary to do so, but if this lens was to be used on an SLR, then more work needs to be done on the aperture mechanism.  There could be something in the aperture mechanism that is defective.

Optical Performance

After cleaning the lens is quite sharp!  I took it out with the Nikon Z 6 to my neighbourhood to test drive it, limited shooting.  With a rubber hood attached, I took some shots and the following are my conclusions:

  • The lens is sharp
  • The colour is weak
  • Boosting colour in LR brings it back to more acceptable performance, or perhaps the profile can be set to saturated when shooting?
  • Straight B&W conversions give good results

190616_089_58f2 Haiou-64

Straight conversion without adjustments

190616_089_58f2 Haiou-64-2

Adjusting “presence” and selective saturation enhancement brings the lens to more modern level.

190616_089_58f2 Haiou-64-3

Straight B&W conversion

190616_099_58f2 Haiou-64-2.jpg

Adjusted for shadow and darkened sky

190615_075_58f2 Haiou-64


190615_076_58f2 Haiou-64


190615_077_58f2 Haiou-64


190615_078_58f2 Haiou-64


At f/2 there is significant vignette, more or less gone by f/4.  Wide open the lens is somewhat soft but acceptable, and sharpness improves by quite a lot stopping down.

Perusing flickr, I found that the lens is very sharp, and capable of giving the famous bubble-bokeh.  Need to do coerce this bokeh out from my copy!

About me

I am an engineer by training, I enjoy photography, love listening to music, and am addicted to scuba diving; hence the nick diediemustdive.  You are here not to read about me, but about the lens I am about to describe, but then you just might be interested to know a little more About Me.  Go ahead and click on that link, if you will.



All information in this blog is meant for sharing of experience and not as instruction, and is no substitute for diligent learning and assessment of competence.  I have messed up my fair share of lenses, and will not be held responsible for any damage caused in the reader’s venture into this fascinating world of mechanical and optical marvel.

You should be conversant with lens repair techniques; beginners should read my earlier blog posts – the Lens Repair series (Lens Repair (1): Some Thoughts, Lens Repair (2): Major Parts of a Lens (Manual Focus), Lens Repair (3): Working from the rear…, Lens Repair (4): Coming from the front, Lens Repair (5): Helicoids) and Richard Haw’s excellent write-ups (Camera and Lens Repair Essentials, Best Practices (part 1), Best Practices (part 2), Best Practices (part 3) and Working with Helicoids).

Mechanical Disassembly

As in all my disassembly, I would try to find a repair manual, exploded diagram or internet  tear-down notes.  I did find an exploded diagram, that was in poor resolution, and fairly complete tear-down instructions (albeit in Chinese).

DF_exploded diagram_03

Exploded diagram, resolution rather poor due to poor original scan.

190613_001_58f2 Haiou-64

First review the mechanical features of the lens.

190613_002_58f2 Haiou-64

Slot at the name plate suggests the approach should be from the front.

190613_004_58f2 Haiou-64

Rear mount has no screws.  The lens external stop-down lever is to the right – a feature added to Auto Rokkor lenses when quick return mirror was introduced in the camera.  There appeared to be a position for a guide pin at the mount (black spot at the bottom).

190613_006_58f2 Haiou-64

And there is a single set screw, I did not explore the function of this set screw.

190613_007_58f2 Haiou-64

This screw is the infinity stopper for the FR.

Most visible features have been described, so the next thing to do would be to proceed with the disassembly.

190613_008_58f2 Haiou-64

Using a lens spanner wrench to access the 2 slots on the name plate.  The make was crude; with some alcohol and some rough sounding movement the name plate came off.  Four screws that appeared to hold the filter ring…

190613_010_58f2 Haiou-64

… turned out to be holding the filter ring and the OU/AU. The filter ring slides out at the rear.

190613_011_58f2 Haiou-64

The (optical unit) OU/AU (aperture unit) all in one piece – to the right is the stop-down lever.

190613_012_58f2 Haiou-64

Replacing these two (filter ring and OU/AU) we will need to align the aperture mechanism lever into the stop-down aperture setting spring-loaded slot.

190613_014_58f2 Haiou-64

The helicoid key (HK) screws are access from the front.  Turning the focusing ring (FR) to minimum focus distance (MFD), the HK screws can be removed.

190614_015_58f2 Haiou-64

HK removed.  Mark orientation.

190614_016_58f2 Haiou-64

Before removing focusing ring helicoid FRH/OUH optical unit helicoid assembly from the barrel helicoid (BH), measure the length at MFD.

190614_017_58f2 Haiou-64

Record that…

190614_018_58f2 Haiou-64

Remove the infinity stopper screw.  Second time seeing this (first was a Rollei QBM lens), and the additional un-threaded part makes it easy to recognize such screws.

190614_019_58f2 Haiou-64

~7 turns CCW, separation at 3m mark.

190614_022_58f2 Haiou-64

The helicoid guide posts are a pair of plates with slot screwed in at the rear.  Reviewed position of OUH in relation to FRH at MFD – would be position after installation.

190614_024_58f2 Haiou-64

I removed the helicoid guide plates, which was not necessary.  CCW removal from back of FRH.  Separation marked.

190614_025_58f2 Haiou-64

3 screws were removed to separate the BH from the mount.

190614_026_58f2 Haiou-64

Left is the BH, right is the rear mount. Aperture control curve is at the top on the AR (on BH) and there is a small ball bearing for aperture detent (~265˚).  Aperture actuation mechanism is with rear mount.

190614_027_58f2 Haiou-64

External stop-down lever, has to be removed if the AR is to be removed.  The AR is on the BH.

190614_028_58f2 Haiou-64

The lens disassembled

Proceed to clean the FRH, OUH and BH with lighter fluid and scrub them clean.  Re-grease, and re-install, in the reverse order.  This is where the earlier markings of separation point is important – the separation points are also the starting points.  If you did not record or mark the points, there will be many trials to get the lens back into the correct order!

Optical cleaning

58f2 Biotar

Optical formula as reference.

190615_041_58f2 Haiou-64

The FOU/AU/ROU.  Front optical unit, aperture unit, rear optical unit.

190615_042_58f2 Haiou-64

FOU removed via external slots.  The screw on the Aperture Unit is to loosen the inner retainer for adjustment of minimum aperture.  Don’t touch the AU screw if you can help it.

190615_043_58f2 Haiou-64

FOU, inner slots of retainer to access E1.

190615_044_58f2 Haiou-64

FOU rear view, E2/E3 commented.

190615_045_58f2 Haiou-64

Front view of AU.  Outer retainer is the for the aperture assembly, inner slotted retainer to adjust min aperture.

190615_046_58f2 Haiou-64

ROU – external retainer removes the ROU.

190615_047_58f2 Haiou-64

E6 removed, there is a retainer but was cleaned in-situ.

190615_048_58f2 Haiou-64

Dimples to remove E4/E5. Cleaned and replaced.  I usually work from inside out; in this case I cleaned E4/E5, replace them, then I proceed to clean E6.

190615_050_58f2 Haiou-64

Returning to the front, remove retainer to E1.  Flip out E1 and cleaned.

190615_051_58f2 Haiou-64

E2/E3 appears built-in, and was cleaned in-place.

190615_058_58f2 Haiou-64

E6 was in a real mess, rear view.

After cleaning, simply reassemble the OU/AU, and pop the unit back into the lens, watching out for the linkages and alignments.

190613_002_58f2 Haiou-64

All optical elements were cleaned with hydrogen peroxide and then rubbing alcohol.   This is after re-assembly of the lens.

190615_065_58f2 Haiou-64

Rear view.

190615_066_58f2 Haiou-64

Where I can, I will also scrub the lens.  Some will even polish the lens, and I had only done so once, on an Industar-50, but found that polishing will also require touch-up paint.  So mostly I settle with the soap and toothbrush approach.


The lens was made in the early communist era when the motto was “for the people”.  But there were few people who were able to “afford” having a camera, since in communist society everyone is equal and so allocation of resource was based on some other priority, e.g. for news, security, etc.  Some of these lenses did make it out of the iron curtain, and in all fairness, the lens performed well, if rough on the edges.  A Minolta Auto Rokkor (I do have a couple), for example, are far better made than this Chinese lens.    Optically, I do not have a Biotar to compare it with, although I do have a Helios-44-2, and I think this lens is better than the famed Helios.

Seems like a keeper.  If nothing else, this is a novelty lens, a Chinese lens, a Biotar.  Perhaps I will get some fun out of it whenever my colleagues and friend in China see me using an ancient Haiou-64 lens in front of my modern Nikon Z 6!

That reminds me I need to get my first Singapore lens (a Rollei QBM lens) back in shape for shooting!

Until next time, bye. If you have enjoyed reading this, or if this article has helped you, please write to me.


A few months ago, my page was blocked for no reason, apparently a bot determined that this is a spam page, presumably it went through the reference pages.  I panicked as I did not have the write-ups backed up!

Fortunately a mail to WordPress gave me back my blogs…

It taught me 2 things:

  • never ever have only an online version – keep a copy on my hard disk (and back them up).  I have heard horror stories of people storing their precious photographs online or in the cloud and suddenly lost their entire collection.
  • I have to rethink about publishing all my tear downs, numbered over 50 right now.

Tell me what you think.


  1. (转载)海鸥64 58mm/f2金属标头完改M42
  2. HAIOU-64 58mm f2 拆解清理
  3. HaiOu-64 白嘴58 2 MD改M42
  4. 海鸥HAIOU-64 58mm 1:2镜头清理

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