{"id":35569,"date":"2020-10-27T17:18:43","date_gmt":"2020-10-27T16:18:43","guid":{"rendered":"https:\/\/kinolios.com\/?p=35569"},"modified":"2024-07-04T21:23:05","modified_gmt":"2024-07-04T20:23:05","slug":"adaptateur-macro-avec-helicoide-pour-objectifs-m42","status":"publish","type":"post","link":"https:\/\/kinolios.com\/en\/blog\/cinematography\/materiel-gear\/lenses\/adaptateur-macro-avec-helicoide-pour-objectifs-m42\/","title":{"rendered":"[En\/Fr] M42 Helicoid Adapter for Macro Focusing"},"content":{"rendered":"
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Cheap, useful and doesn\u2019t lose infinity<\/h3>\n

Presentation of a small and handy adapter that I recently found while scouring eBay.<\/p>\n

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As always, a full list of the articles in this blog can be found HERE<\/a>.<\/em><\/p>\n\n

Introduction<\/h4>\n

There is a huge number of vintage lenses that don\u2019t have adequate close focus capabilities. This is especially true for most rangefinder lenses, like the Mir 1b seen on the cover photo of this post, which only focuses down to 70cms.<\/p>\n

As soon as you want to shoot details, make the bokeh stand out or shoot proxy, you feel limited in your composition as you can\u2019t come close enough. If it\u2019s possible to crop the photo in post, it is a deal breaker in video as you can\u2019t really zoom into the image more than 120% without a visible loss in quality.<\/p>\n

There already exist alternatives, like using extension tubes, but they have a lot of downsides, like losing the ability to focus at infinity so you have to constantly take them on and off depending on what you want to shoot. This also means exposing the sensor to the elements every time you change them, which doesn\u2019t help in keeping it clean.<\/p>\n

You can also use a close-up lens, but it can interfere with other filters and also prevent the lens in achieving infinity.<\/p>\n

All these limitations meant that I don\u2019t use the Mir as often as I would like, even if it has a really nice image texture and a great swirly bokeh, which would also pop out more if it could focus closer.<\/p>\n

I finally found an acceptable solution on eBay, and it works for all M42 lenses (and M39 with a M39 to M42 ring). Instead of using a standard dummy M42 to E mount adapter, I mounted a M42 to M42 helicoid adapter on a thin M42 to Sony E mount ring. This way, the helicoid acts as extension tubes once you want to get closer and drastically reduce the focusing distance, but can be retracted to restore the original focus scale, and focusing to infinity.<\/p>\n

Both pieces cost me about 30$, which is not a lot compared to the potential it offers to a lot of lenses in my collection.<\/p>\n

To choose the right length of the helicoid, you first need to know the difference between the M42 and E mount flange distance. For M42, it is 45,46cms, and 18cms for the Sony E mount. Then the adapter needs to be 27,46mm (45,46 \u2013 18) long. The M42 to M42 helicoid has a 25mm length, so the ideal thickness would be 2,5mm for the E mount ring. I couldn\u2019t find any so I settled for a 1,5mm thick one.<\/p>\n

It\u2019s not ideal, but it\u2019s better to be too short rather than too long, as it makes sure that you will be able to achieve infinity even with badly serviced lenses like my Mir 1b seems to be.<\/p>\n

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The two parts of the adapter. The black tube is a 25 to 55mm extension tube with M42 thread on both sides. The ring is a M42 to E mount thin adapter.<\/em><\/figcaption><\/figure>\n<\/div>\n
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Handling<\/h4>\n

The helicoid at full extension is equivalent to a 30mm extension tube. The shorter the focal length of the lens is, the stronger the effect this will have on the focusing distance.<\/p>\n

The two parts are made from metal and feel sturdy. Even fully extended, there is no sag or flexing even with a moderately heavy lens like the Takumar 135mm F2.5 seen below. I wouldn\u2019t mount monsters on it like the Jupiter 6 unsupported though, as the lever the adapter creates could damage the mount of the camera.<\/p>\n

The central ring of the adapter, which controls the extension length, as a really high resistance. This is good, as it prevents accidental manipulation or the weight of the lens changing the settings. Another good thing, the lens won\u2019t rotate while extending the helicoid, so the markings stay on top. This can also be useful with polarizing filters as their orientation stays the same.<\/p>\n