REVIEW: Carl ZEISS 28mm f/2.8 Biogon T* + 1.5m pcx filter

The Contax G 28mm Biogon was considered one of the best 28mm available on film, but suffers serious issues on digital due to sensor cover glass. Can a simple filter make the lens a competitive performer on Sony cameras? Find out below.

I have shot this lens for years on the Sony A7 and more recently with a PCX filter and then on a Kolari UT modded A7. Unless otherwise noted, all of the tests in this review were performed on a Sony A7RII with a reversed 1.5m PCX filter on the lens (Thanks again to Nehemiah for lending me the A7RII). Check captions on sample pictures to see what camera was used. Bonus: The Contax G 28mm Biogon is both Phillip and my favorite lens on aps-c cameras, so I will also add a second installment later reviewing the lens for aps-c provocatively titled How the A6000 + Contax G 28/2.8 is better than an RX1.

Sample Images

Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/2.8
Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/8
Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/11
Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/11

Specifications

Diameter56mm
Length31mm (+ 3-6mm for PCX filter)
Filter Thread46mm
Weight150g
Max. Magnification1:15
Close Focusing Distance from the sensor50cm
Number of aperture blades6
Elements/ Groups7/5

More information in Zeiss’ official data sheet.

Versions

There is only one version of this lens. It comes in two colors: Titanium and black but black is much rarer (and more expensive).

Compatibility

The Carl Zeiss Contax G lens line was originally developed in the mid 90’s for the Contax G1 and it’s successor the Contax G2. Both are AF rangefinder cameras.

Adapting Contax G lenses to modern digital cameras comes with two challenges. Since the Contax G cameras have a rather short flange focal distance of just 29mm you cannot adapt them to DSLRs. The advantage of this short flange focal distance is that adapters for mirrorless systems are only about 11mm thick. The other problem is that the lenses do not have a focusing ring, just AF coupling so the adapter must provide some means to focus the lens.

There are two kinds of adapters, purely mechanical and electronic adapters.

Mechanical adapters are available for EOS M, Fuji X, M43 and Sony E-mount. They come with their own focusing ring. They range in price (affiliate link) from $25 to $140. I own the Kipon one (or possibly a cheap knockoff since I got it second hand for ~$30) and it works fine on all the lenses but the 90mm (which I had trouble focusing accurately at near distances with). Focus is a little rough and in the wrong (Nikon/Pentax) direction, but perfectly serviceable. I have heard good things about the Metabones and Fotodiox Pro adapters but I haven’t used them personally.

The Techart TA-GA3 adapter is very interesting because you can use AF with newer Sony E-mount cameras! AF with the Sony a7, a7r and a7s is unusable (very slow and unreliable) but with the newer cameras it works quite okay most of the time and gives you all the quickness and accuracy of a screw-drive AF lens on a dslr from 2005 (if you have used one of these you will know what I mean).

The AF experience is certainly not as smooth as with native lenses. The screw driven AF is rather loud and while it tracks small changes in focusing distances well it is quite slow to realize larger changes in focusing distanceReliability was mediocre and not near the same level as the native lenses. It also fails when it is a bit darker in situations where native lenses still work reasonably well. I it found unusable, but then that performance level of AF is what drove me to manual focus in the first place, and some people seem to use it without major complaints. I changed to manual focusing which is realized with a small wheel at the 2 o’clock position. Manual focusing with this method works better than I would have expected but can be a bit fiddly at long distances.
The Techart TA-GA3 adapter sells for about $250 at ebay.com or amazon.com (affiliate links).

Build Quality

Carl Zeiss Contax G 28mm f/2.8 Biogon disassembled
Carl Zeiss Contax G 28mm f/2.8 Biogon disassembled

The Contax G 28/2.8 feels very nice and solid.

The barrel is made of aluminum.

All markings are engraved.

The Biogon is made in Japan.

I have disassembled the lens and while it is well engineered and made mostly of metal it does not seem as robustly constructed as typical Leica, Zeiss, and Cosina/Voigtländer manual focus rangefinder lenses. I would expect it to be more likely to develop problems due to a sudden impact than the previously mentioned manual focus rangefinder lenses.

Size, Weight and Handling

The Contax G 28mm is very well balanced on any Sony e-mount camera. At just 150g with a small diameter and the short adapter it is significantly smaller than the FE 28/2.0 (even with the added filter) or most adapted 28mm lenses (even many rangefinder 28mm lenses).

The Contax G lens line does not have a focusing rings. How you focus depends on the kind of adapter you use. I convert my lenses to m-mount with a real focus helicoid, but have found the Kipon adapter to be perfectly serviceable as well for non-moving subjects. Info on how I did my conversions can be found on this Fred Miranda thread. For info on AF with the Techart adapter, see the compatibility section above.

You can also see the impact point where I dropped the lens on camera into a rocky stream. ;)
My modified my Contax G 28/2.8 with a rokkor helicoid and an M-mount.

The aperture ring has full stops from f/2.8 to f/22 which register nicely but it isn’t too easy to select half-stops because the aperture ring doesn’t travels very far.
If you use the Techart adapter it won’t record the actual aperture you used. You can change the aperture in the camera but all this does is that it overexposes your image by as many stops as you have stopped down (e.g. f/5.6 will result in a 3 stops overexposed image).

Lens Hood

The Contax Metal Hood GG-1 screws into the filter ring, has a little larger diameter than the lens, has 55mm filter threads, and it is about 10mm deep. It is made of aluminum and provides decent protection for the front of the lens.

Filters

The 46mm filter thread is made from metal.

The front of the lens does not rotate so polarizers are easy to use.

Image Quality

Vignetting/Colorcast

At f/2.8 vignetting is very  strong and it remains quite strong as you stop down. According to Zeiss, small improvement in vignetting on stopping down is one consequence of Biogon lens designs. In addition to strong vignetting, there is also significant color shift towards the edge of the frame when used on cameras without backlit sensors (A7, A7R, A7S, A7II, A7SII). This color shift can be eliminated with a few clicks using the Lightroom Flat Field Plug-in once you have made a profile photo by shooting a uniformly illuminated white subject (like I did to generate the vignetting examples below). Correcting this level of vignetting will definitely increase noise towards the corners of the frame.

Sony A7 | Raw | LR CC default settings
Sony A7 | Raw | LR CC default settings

On my A7 the wide open vignetting is around 2.5 stops and never drops below 1.5 stops. The backlit sensors reduce the vignetting as well as the color shift. On the A7RII vignetting is only 2 stops wide open and falls to 1 stop by f/8.

Sony A7RII | Raw | LR CC default settings
Sony A7RII | Raw | LR CC default settings

In some cases I actually prefer the color shift effect:

uncorrected vs corrected color cast | Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX | f/5.6
uncorrected vs corrected color cast | Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX | f/5.6

Flare Resistance

The flare resistance of the Contax G 28/2.8 is good but not great. Under extreme conditions with the sun in the frame you can see some slight veiling flare which causes slight contrast loss, but contrast remains better than any other 28mm lens I have used in such situations (including the FE 28/2). In most situation contrast is great. Unfortunately, ghosting can also occur with the sun in the frame as well as long streaks of light.

Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8

Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 + 5m PCX | f/5.6

Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/11
Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/11

The Contax G 28/2.8 will also very occasionally show a smear of light in the image when the sun is just outside the frame.

Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + OptoSigma 5m PCX filter | f/4
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + OptoSigma 5m PCX filter | f/4

Bokeh

At f/2.8 the Contax G 28mm has somewhat busy bokeh with more defined out of focus highlight discs towards the corners of the frame and significant business in the transition zone.

Stopped down to f/4.5  the bokeh is much smoother but you will clearly see the hexagonal shape of the aperture blades at f/5.6 and smaller.

  • Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
    Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8

  • Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/4
    Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/4

  • Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/5.6
    Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/5.6

  • Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8
    Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8

Hint: larger images can be viewed by clicking on the image.

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/4
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/4

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/11
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/11

  • Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/2.8
    Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/2.8

  • Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/5.6
    Sony A7 | Carl Zeiss Contax G 28mm f/2.8 Biogon | f/5.6

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/2.8

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/4
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/4

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8

So all in all bokeh is not a strength of this lens, but it is better than many of other 28mm lenses. I tend to like it better at a distance than closeup.

Distortion

The Carl Zeiss Contax G 28mm f/2.8 Biogon has negligible pincushion distortion on it’s own that can be corrected with -1 correction in Lightroom. Adding the reversed 1.5m PCX filter induces a little bit more pincushion distortion. This can be easily corrected using -3 correction in Lightroom.

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/8

Chromatic Aberrations

There is some lateral CA, but it is small enough to be easily corrected with minimal loss in image quality.

Coma

Coma correction is not great wide open, but improves a great deal stopping down to f/4.

Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX | f/2.8

Even at f/2.8 coma is not so bat that it will ruin astro or night cityscapes.

100% crop from upper left corner | Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
100% crop from upper left corner | Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8

Note, these coma tests were done on a Sony A7 with the Kolari UT mod and 5m PCX filter, not the A7RII with 1.5m PCX filter. I don’t believe there would be any significant difference, but I haven’t been able to test yet due to uncooperative weather.

A much bigger concern than coma for shooting cityscapes is sensor reflections when using the original A7. In my experience, sensor reflections seem to be worse when using wide angles designed for rangefinders such as this Biogon.

Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon+ 5m PCX | f/5.6
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/5.6

Sunstars

The Contax G 28mm has only 6 aperture blades so sun stars have only 6 rays and are not well defined. In fact, they remain more diffuse balls (which I personally prefer) than stars till f/8 or smaller.

Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + OptoSigma 5m PCX filter | f/4
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + OptoSigma 5m PCX filter | f/4
  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/5.6

  • Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/11
    Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX | f/11

Sharpness

"100%
DNG for flat field correction of vignetting and color shift–>Adobe Lightroom CC classic (default settings)” class=”size-full” /> 100% crops | A7RII on tripod with remote | RAW–>DNG for flat field correction of vignetting and color shift–>Adobe Lightroom CC classic (default settings)

When used on Sony cameras without a correction filter the Contax G 28mm shows extremely strong field curvature and astigmatism. The reversed 1.5m PCX filter does wonders to correct this though. See here for a comparison of the naked lens to different correction lens configurations on an A7. See here for a comparison of the lens on a stock A7RII with a reversed 1.5m PCX filter to the lens on a Kolari UT modded A7 with and without a 5m PCX filter. Finally see here for a direct comparison of the Contax G 28/2.8 to the Sony FE 28/2. Note: the linked comparisons use my (rather aggressive) print sharpening rather than the Adobe defaults used above.

f/2.8: Excellent contrast and sharpness in the center, the midframe region is good, but the edges and corners are considerably weaker.

f/4: The edges are excellent as well now, corners remain a little weaker.

f/5.6: The corners are very good as well now.

f/8: Excellent across the frame.

f/11: A little less sharp due to diffraction.

For landscape photography if you have a lot of detail into the corners you should stop down at least to f/5.6. For other applications with a three dimensional subject at any aperture you can put your focus anywhere in the frame without worrying about sharpness.

Color

I have always really liked the colors I get with Zeiss Contax lenses (as well as Minolta and Leica lenses) and have generally been unable to replicate them in post using lenses from other brands. Here is how the colors of the Contax G 28/2.8 Biogon (left) compare to those of the FE 28/2.8 (right) at f/5.6 (shot on the Kolari UT A7):

 

It seems clear from this comparison that the differences in color between the Zeiss and Sony lens are actually quite small, which goes against my impressions from real world shooting with both lenses. Looking closer at the images does show that there is a little more fine differences in brightness within each color square with the Zeiss lens. Perhaps it is actually better high frequency contrast with the Zeiss lens that is contributing to my impression of better color by making subtle tonal gradations more visible (or maybe it’s just the placebo effect).

 

 

The differences is more noticeable at f/2.8 (all these shots were taken at the mfd of the FE 28 where neither lens should really be at it’s best):

 

Alternatives

Sony FE 28/2The Sony is a stop faster at f/2 with fast autofocus, smoother bokeh, and less ghosting in extreme conditions. Downsides are worse build quality, lower contrast, and strong distortion which needs to be corrected as well as the higher price.

Voigtlander 28/2 VM: A modern manual lens which is more expensive, bigger, and heavier, but faster with very good sharpness from wide open, good flare resistance and nicer sunstars. It has some issues with the Sony a7’s thick sensor stack that can’t be easily corrected with filters, so it is not as good for landscape.

Pentax K 28/3.5: I have not shot this lens, but  it is Phillip’s favorite legacy 28mm for landscapes. It appears to have better flare resistance and substantially less vignetting. It is much larger though and probably slightly lower in contrast.

Zeiss Distagon 28/2.8: The Contax/Yashica Zeiss is SLR contemporary of the Contax G. It is much bigger and has similar contrast and flare resistance. The Contax G Biogon (+ PCX filter) has slightly better corners and lower distortion, while the Contax/Yashica Distagon has slightly better midzone performance at large aperture and much better vignetting performance.

Nikkor 28/2.8 AIS: Unlike the rest of the legacy lenses listed above, the Nikkor has a floating element for better closeup performance. It’s bigger and not as sharp in the corners near infinity (though not far behind), but has better bokeh and very good closeup performance.

Minolta MD 28/2: This is the only other 28mm I have kept. It lacks the small size, contrast, flare resistance, and corner sharpness of the Contax G. It does have a lower contrast look wide open that I enjoy for people and bokeh though and is a solid performer for landscape.

Conclusion

pros

  • Great sharpness and contrast from f/2.8
  • extremely small size
  • Build quality
  • Price
  • Distortion control
average

  • CA
  • 6 aperture blades
  • Flare resistance
  • Bokeh
cons

  • Heavy vignetting
  • Adapter based focusing
  • Requires a correction filter
  • Color shift using some cameras

The  Zeiss Contax G 28/2.8 Biogon is one of the smallest FF 28mm lenses that can be mounted on e-mount cameras. It also has very good performance across the frame from wide open (with the PCX filter). No matter the aperture or location in the frame the lens has incredible bite at the focus point. It outperforms the native FE 28mm and all of the legacy SLR 28mm lenses I’ve tested in terms of sharpness and contrast at large apertures. Unfortunately, The ergonomics are substantially behind even that of your average legacy manual focus lens. In addition, vignetting and and flare resistance are well below the level of modern native lenses.

If you are looking for a landscape or street shooting 28mm and don’t mind pre-focusing or slow manual focusing the Biogon is a tough lens to beat, particularly for the price. For those who demand fast focusing, good sunstars, or imperviousness to flare the Biogon’s performance represents a serious compromise.

All in all the Contax G 28/2.8 Biogon is an excellent performer from wide open with a good price to performance ratio and fantastically compact size. Adapter focusing is a serious compromise though that will turn off many users, while using PCX filters adds additional complexity and cost. 

The Carl Zeiss Contax G 28mm f/2.8 usually sells for around $250 used at ebay, around 250€ at ebay.de or occasionally on Amazon (affiliate links). The rarer black version sells for quite a bit more.

If this review was helpful to you, please consider using one of my affiliate links. I will earn a small commission on your purchase and it won’t cost you anything. Thanks!

More Sample Images

Additional samples are available here: Contax G 28/2.8 set on flickr.

All images are processed in Lightroom from Raw.

Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX filter reversed | f/2.8
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX filter reversed | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX filter reversed | f/4.5
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX filter reversed | f/4.5
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/5.6
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/5.6
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX reversed | f/11
Sony A7RII | Carl Zeiss Contax G 28mm f/2.8 Biogon + 1.5m PCX reversed | f/11
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/2.8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8
Sony A7 Kolari UT | Carl Zeiss Contax G 28mm f/2.8 Biogon + 5m PCX filter | f/8
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26 thoughts on “REVIEW: Carl ZEISS 28mm f/2.8 Biogon T* + 1.5m pcx filter”

    1. All my tests are on the a7rII (except coma and color), and with the PCX filter it is very good on the a7rii – noticeably better than the FE 28 in terms of sharpness and contrast.

  1. First thing I thought with the color checker was difference could be a matter of brightness- which you then mentioned. Then went back and I think I see a slight color difference? Same conclusion:) Maybe it’s me. That placebo force must be strong with this one…

    1. There is definitely a color difference, it’s just not very big as viewed on the color checker. I think flat color patches are probably not the best way to view differences in color response, though the color checker passport is good for normalizing color casts between lenses. I suspect differences would show up better with subjects that have lots of tonal gradations. I will have to think of an additional subject for controlled tests.

    1. The A7II should do as well as the A7 classic with the PCX filter – very good sharpness/contrast, but with more vignetting and color shift than the A7RII. I agree about the G28 on the NEX-5N, I wish the G45 on the A7 series was as nice as the G28 on the 5N.

    2. I’m in the same boat! Loved the G 28 on my NEX-5R, but don’t touch it with my A7. Don’t shoot a lot of lenses for which the thin filter mod would make sense. Haven’t tried the PCX filter, but would like to one of these days.

  2. Great review! Looking forward to the APSc instalment. I need something around 28mm and if the smaller sensor cuts off most of the problematic corners I’m wondering if there are non-obvious (size, price) adavantages of this lens lens over the cv28/2.

    1. It’ll probably be a little bit till I have the aps-c supplement out. I’ll probably write one or two other things first. The G28 is definitely a better lens for landscape on aps-c imo than the cv 28/2. The extra stop and smoother bokeh of the cv are worth considering though.

  3. Thank you for your comprehensive report on CZ Biogon 2,8/28. I like to use this lens of my old Contax G1 gear on a recently acquired used Sony A7R.
    Instead of the recommended PCX filter 1.5m (= 0.67 dpt) I mount the Nikon close up 0 lens (= 0.7 dpt) in the reverse position. It significantly improves the sharpness in the corner. A direct comparison with PCX 1.5 m is not possible for me. But I suspect a comparable image improvement.
    Corner cast is known to be a big problem with rangefinder wide angle lenses on the A7R. I use RawTherapee and flat-field correction .

    1. Dear Guenther,

      I am also considering the Nikon Nr. 0 closeup lens to correct a G28. How did you reverse the lens and attach it to the 46mm G28?

      regards,

      1. Dear Markus,
        in the meantime, I was able to test the combination Nikon close up 0 in reversed position on the Biogon 2.8 / 28mm G. The results do not satisfy me 100 percent. While the sharpness in the center decreases very little and the sharpness in the middle range at aperture 2.8 to 5.6 improves significantly, there is no improvement in the corner and edge area compared to the lens without correction lens. If I compare my shots with the test shots on https://c1.staticflickr.com/5/4632/26468897938_66cdfba901_o.jpg the Nikon lens can not keep up in the edge area.
        The reversal position I have achieved with a reversal ring of 52 mm to 49 mm and a step-up ring 46/49 mm. I found this reversal ring in my collection by chance. It is not that easy to get.
        For my Biogon G 2.8 / 21mm lens, I inserted the 52mm Nikon c.u.0 lens into a 55mm filter socket and balanced the difference in diameter with a layer of black electrical tape.
        If you are satisfied with the imaging result and want to remove the meniscus lens from the filter socket and want to grasp it directly:
        Put the conversion lens upside down on a table. The glass is set in a bent metal ring. With a fine screwdriver you can cautiously begin to bend this clamp at one point and continue this in a circle. Make sure that the screwdriver does not slip or scratch the glass. The tipped lens has a diameter of 49 mm. You can put them back in the same Nikion filter ring, rebent it and screw them into the filter thread via a step-up ring 46-52 mm.
        Currently I am testing a two-part correction lens on the Biogon G 2,8 / 28mm of commercially available super-coated spectacle lenses. Front +0.25 D with the convexity to the front, behind +0.50 D with the convexity to the lens [front () Biogon]. The image performance is much better than with Nikon c.u. 0 in all three image areas and captured in a 46 mm filter ring no vignetting occurs.
        I can not currently offer a direct comparison with the 1.5 m PCX lens, but I think quality of image is similar.

        1. In the meantime, I have noticed that there are at least two versions of the Nikon close up 0 52mm conversion lens. They differ by the radius of curvature of the meniscus. The obviously older version has the larger radius, so it is less curved. If you use the concave surface as a mirror, its mirror image is larger than in the more curved meniscus. The flatter lens is better suited as an attachment for the CZ Biogon 2,8 / 28 G and for the Biogon 2,8 / 21 mm. The sharpness is improved not only in the middle zone, but also in the edge area. At the edge, the PCX 1500 filter is probably a little better. The newer version of the N.c.u. 0 is worse in the edge and corner of the picture.

  4. I got a lot out of the colour comparison. Having an actual comparison I was able to see what typically is only talked about. I can see a difference in the lighter colours, FE does look more mat? muted to me, but I also see that the frame around the individual colours is a tad less defined as well (on FE). When I scrutinise on the black and white the FE appears more pleasing to my eyes??? I wonder if due to the mat/ muted appearance??
    Now if you could show the same with contrast!!!!!

    Well done Sebboh and thank you

  5. I just realized a lot of these pics are in Portland, OR. I realized it when I got to the shot of the bench on the lake at the rhododendron garden 🙂 It’s one of my favorite place here and I go as often as I can. Cheers!

    1. Yup, most of the shots were taken in Portland (or around it), a few in San Francisco. I spend a lot more time in Forest Park, but I go to Crystal Springs pretty regularly.

  6. Thank you for this interesting article. Some of your photos with this lens seem to be of subjects that are closer than the 0.5M minimum focusing distance. Does the frankenlens conversion allow you to focus closer than the original lens housing did?

    Thanks again.

      1. Thanks. I bought the G28 based on some of the photos you’ve taken with it, but it’s been too long since I used a rangefinder and I’m finding the 0.5M MFD to be very limiting. So now I’m considering doing the conversion. If you don’t mind me asking, what did you end up using as spacers to hold the optical assembly in place, and for the gap between the aperture ring and the new mount? How did you do the aperture linkage?

        Thank you!

          1. Wow, very cool. I especially like the new aperture ring. Thank you for sharing, you’ve been a big help and an inspiration for a new project. I can’t imagine I will figure out how to do this, but I’m going to try. The G28 is worth it. But I don’t have to tell you, you have two.

          2. Ha, I only have one. The other in the picture is one I’ve converted for somebody else.

            I believe somewhere in the archives of that FM thread are files that can be used for a CNC machine to make the spacer rings.

  7. Thanks. I see references in other threads to the STL files but unfortunately it looks like whoever originally posted them deleted them.

    1. No, I posted them. Fred as changed how the website archives things and they’ve disappeared into unreachable archives. I will ask him if there is a way to reinstate those old posts. I can email them to you if you’d like as well.

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