Thirty months with Samyang 135 f/2

It’s been well over two years since I got into my hands Samyang 135 f/2 glass and use it as my primary astrophotography lens. Since that time I found out, that all positive reviews about this lens proved to be true. This lens is optically close to be perfect, well built, and still compact. During these 30 months of using Samyang my portable imaging setup evolved a little.

Bayonet replacement and aperture stop ring

I use Samyang to astrophotography mainly with QHY163 camera, so I needed adapter between lens bayonet (Canon EOS in my case) and T2 astronomical thread. I tested two or three adapters and all turned out to be not stiff enough. Small springs in adapter’s female bayonet mount was too soft to keep lens and camera in well defined position. f/2 focal ratio is pretty demanding. So I decided to remove (unscrew) bayonet from the lens and put there custom CNC machined adapter ended with male T2 thread. It provides nice and rigid connection.

Another thing that I decided to add to my system was aperture stop ring. Samyang 135 provides very good quality image even at f/2 full open. However if you aim at perfect pinpoint stars you may want to stop it a little. If you use lens aperture iris to stop it down, then stars will have spikes. If you like this effect, then it will work for you. But if you want to keep spikeless “apo” look, then you need to have aperture stop ring that is fixed to the lens front. You may use lens filter thread to mount this ring. I ordered custom CNC machined ring with aperture 50mm, that gives effective focal ratio of f/2.7. At the image below you can see star shapes at f/2.0, f/2.4 and f/2.8.

Mounting bracket for lens, guidescope and electronics

Another customization I added to this lens was lightweight mounting bracket with guidescope rings and electric box. Since I use this lens at my portable setup and it travels with me a lot, low weight and compactness of whole setup is crucial. I designed and 3D printed dedicated brackets to this lens that additionally hold lightweight 30mm guidescope ring. On the other side I have mounted the powerbox. This box contains 12V power splitter, 8V regulator (for DSLR) and USB3.0 active hub. Now whole setup is really compact and preparing to session takes notime.

Last but not least addon to my Samyang 135 f/2.0 lens was simple lever printed with 3D filament that I use to increase precision of setting perfect focus. At f/2.0 very little movement is required at the last stage of focusing to get pinpoint stars, especially when you use modern CMOS small pixel camera. This simple lever makes this process easier.

Some of these printed elements are available in the store, so you can also equip your Samyang 135 to astrophotography. Unless you don’t have this lens yet, but, well, why don’t you? 🙂

Samyang 135 f/2 astrophotography gallery

Below some pictures I made using Samyang 135 lens with QHY163 mono camera and iOptron Smart EQ Pro mount.