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Hey, I have found myself a cheap Samyang 135mm f/2 lense. Now I just need the rest of the “rig”. I have my EQ6-R Pro mount and ZWO 2600MM camera. What’s the best options for attaching lense etc. to my mount and what do you all do for Auto focusing? Any advice are welcome 🤪 |
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| https://www.pierro-astro.com/materiel-astronomique/accessoires-astronomie/roues-%C3%A0-filtres-et-accessoires/support-filtres-%C3%A0-tiroirs-pour-objectif-canon-eos-zwo_detail You can use something simple like this, or you also Can found an adaptator available with filter wheel https://astronomy-imaging-camera.com/product/nikon-lens-adapter-for-2filter-wheel/ |
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| Having spent a small fortune on Rokinion mounting kits, I've found this to be the best option. It has two finder shoes so you can easily mount a guide scope and power distribution and/or miniPC, plus a separate plate for an EAF. I also like how the bolts are attached to the device whereas others must be completely removed. |
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You can either print something yourself: https://www.thingiverse.com/thing:4761672 or you can buy something like this from TeleskopService (it comes with everything you need): https://www.teleskop-express.de/shop/product_info.php/info/p14230_Wega-ZWO-EAF-Adapter-mit-Schelle--Schiene-und-Sucherschuh-fuer-Samyang-135-mm-Objektiv.html The Option from Eteocles looks nice aswell. |
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I use the Astrodymium kit which is excellent, but they're not producing anymore it seems. As for the camera it depends on which filter wheel you have, if you have 2" then you can use the ZWO adapter, if you use the 36mm one it's a bit more difficult. I have my guide scope, EAF and AA+ attached to my Astrodymium kit, I 3D printed a bracket for the AA+. Then it's a matter of adjusting your backfocus which may require a fair bit of testing, I ended up using one of the thin shims that came with my camera in order to get it more or less perfect for my sensor. I just did a lot of image runs while inspecting the stars, while changing the setup. Edit: Didn't think about what mount your lens might be, my comments is regarding the Nikon version. If you have a Canon version you can replace the lens flange with a M48 ring. |
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Check the Samyang Equipment page, I have uploaded pictures and stl´s for 3D printed parts there. https://www.astrobin.com/forum/c/equipment-forums/samyang-135mm-f20-ed-umc/zwo-eaf-adapter-ring/ For focussing the Zwo autofocusser works really well, the zwo filter holder for Nikon/Canon allows you to easily use filters and to adapt to your cooled camera. I think vignetting is quite pronounced even though I only use an APS-C sensor but it can be calculated out well with flats. Michael |
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I use the Astodymium Ring System. To attach it I use the ZWO adapter with filter drawer. Backfocus works out to about 44mm using the 11mm collar on the camera and the 26.5mm for the filter drawer/adarerpter and 6.5mm fir the camera sensor. focus is handled by the ZWO EAF.    |
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| @Jan Erik V , do you have more information on how to directly adapt the canon version to 48mm? |
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Michael Ring: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html Only available for Canon as far as I know, simple replacement but it will change the backfocus distance a bit. |
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Many thanks! I found a good priced cannon version of the Samyang, hope it is still available… Beeing able to directly adapt to the camera is a big plus! Michael |
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Interested to hear people's thoughts on the best adapter to connect lens and camera. I have the Nikon version of the Samyang 135 mm and recently bought a RisingCam APS-C format cooled camera. I grabbed a ZWO Nikon lens adapter which *should* do the trick. The optical thickness of the adapter is 29 mm which with the 17.5 mm offset of the camera should exactly match the 46.5 mm back focal distance of the lens. However, analysis of star shapes in ASTAP is showing field curvature which I don't see when I mount the lens to a Nikon DSLR. Shimming the lens out a touch only increases the curvature, indicating that I really need to get the camera closer to the lens which is impossible with the adapter I have. There also seems to be 'flex' in the adapter, which introduces tilt as you point to different parts of the sky. It's not helped by the fact that the camera is fairly heavy. Interested to hear if anyone else has seen these issues and managed to overcome them. |
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James Tickner: I use the ASI533 so I don't get any severe issues regarding tilt, but I have noticed some very slight movement in the adapter. However my adapter is 20mm, then the EFW is another 20mm, + 6.5mm from my camera. My filters are 3mm thick so I have resorted to adding one of the smallest shims. https://www.astrobin.com/1ds9r7/ This is the image I made from my test session, four frames, the squid was shot with no adjustments and the elephant trunk was done with the shim inserted, the opposite corners were also made with various thickness shims. I used the back focus spacing guide from OPT as a guide: https://www.google.com/url?sa=i&url=https%3A%2F%2Foptcorp.com%2Fblogs%2Fdeep-sky-imaging%2Fhow-to-set-the-correct-back-focus&psig=AOvVaw3kEpPAtS4CxIYcFTpqdxl5&ust=1691669063424000&source=images&cd=vfe&opi=89978449&ved=0CBEQjRxqFwoTCMCntb_Ez4ADFQAAAAAdAAAAABAE I haven't done any tests as to how far i can push the lens for good stars but shot mine at F/4, the nebula was shot at F/2. What I can say though, is that the slight movement in the adapter didn't matter on my sensor - the backfocus however did. The squid has a lot of issues compared to the trunk in my image. That said, your sensor is bigger and would suffer more from any inaccuracies. Does the RisingCam have a fixed 17.5mm backfocus or can you remove parts to get 6,5mm? Getting a holder ring for the camera is one way to go, I have one but it's not compatible with the Astrodymium unless I print parts that matches exactly the height from the dovetail. It has to be very precise. |
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James, you have a very similar config to the one I have, you should use Nina's abberation inspector to properly shim the lens, with this tool it is very easy to get the distance from the sensor properly dialed in. If you want I can look up how much extra shimming I needed, perhaps this info is already good enough to bring you in the right ballpark. And yes, flex is an issue with the adapter, I wanted to fix the issue by 3d printing another holder for the camera itself, now I will very likely buy a quite cheap Canon Version of the lens on Monday and will use the 48mm adapter that Jan pointed me to... Michael .. I will also report back if the 48mm opening helps with vignetting on APSC-Sensors.. |
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Michael Ring: The problem is that I need a 'negative' shim thickness! In other words, I have curvature with no shim that gets worse if I shim even a little bit, implying that I need to get the camera closer to the lens. I bought the camera with the AR glass and have added a UV/IR cut filter inside the ZWO adapter, so I wonder if that is the cause of the problem ... I also came across the Geoptik adapter here Teleskop-Express: Geoptik Adaptor for Nikon lenses to T2 for CCD cameras - w/ 1/4" thread This seems to have quite good reviews and also has the advantage that the optical distance is only 21 mm, so I could add T2 adapter tubes and shims to get exactly the back focal distance I need. Unfortunately though it only takes a 1.25" filter which seems a bit small for an APS-C sensor. Has anyone tried this adapter? |
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I use the ASI533 so I don't get any severe issues regarding tilt, but I have noticed some very slight movement in the adapter. However my adapter is 20mm, then the EFW is another 20mm, + 6.5mm from my camera. My filters are 3mm thick so I have resorted to adding one of the smallest shims. Which adapter are you using that is 20 mm thick? That could be an option for me with a T2 extension tube. Does the adapter allow a 2" filter to be inserted. Unfortunately I think there is no backfocus adjustment on the camera itself. There are four mounting bolts on the front surface but they are clearly labelled DO NOT OPEN and I'm not game to break a brand new camera just yet  The idea of 3D printing a cradle to hold the camera on the correct alignment is a good one, but I was hoping to find an adapter that is naturally stiff enough to make this unnecessary. Maybe this is too optimistic! |
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I have both the Canon and Nikon ZWO filter drawer/adapters. Mine are both pretty solid, though the Nikon one has a tiny bit of slop in the lens connection. Nowhere near as bad as my QHY lens adapters or the old ZWO lens adapter. If you are doing OSC with a filter I think the ZWO filter drawer/adapter is a must-have. For a FW it gets more complicated, particularly for APS-C. You'll need 2" filters and those FWs are pretty heavy. I'm always wary of trying to hold that much weight in a PETG kit. |
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Very strange, my Nikon adapter needed additional shimming. I also use UV/IR Filter and it will make your life easier because it increases backfocus by 1/3 of the thickness of the filter. You could try a thicker filter if you have another UV/IR filter. Please try Nina anyway, perhaps there is a bug in your thought process, you should always have to add shims when you include extra glass in the form of a filter. Did you receive the new or the old vewrsion of the Camera? The new version alows you to reduce backfocus by 5mm. I did not use this feature on the camera that has it, so I cannot tell if you need to buy an extra part or not, but the guys from Risingcam should know... |
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James Tickner:I use the ASI533 so I don't get any severe issues regarding tilt, but I have noticed some very slight movement in the adapter. However my adapter is 20mm, then the EFW is another 20mm, + 6.5mm from my camera. My filters are 3mm thick so I have resorted to adding one of the smallest shims. Yeah, I wouldn't open it. I didn't think of the tilt plate on those cameras. The adapter I have is for the 1.25" or 31mm filter wheel so there's no filter drawer there unfortunately. https://www.firstlightoptics.com/zwo-accessories/zwo-efw-nikon-lens-adapter.html They also make this one: https://www.firstlightoptics.com/zwo-accessories/zwo-nikon-lens-adapter-for-2-filter-wheel.html I don't know if any of those would make a reliable "MacGyver solution" to your problem somehow, but if you're looking for a factory made option I don't know of any. I would however try it without the filter just to see how it affect things. It seems very strange that the exact focal distance seems to be too long. Have you measured everything to see if it all checks out and ruled out any inaccuracies within the different parts? |
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I have ordered the Wega option from Teleskop-Express…I don’t have a 3D printer 😉 and also the M48 option as the Samyang lens I have is the Canon version. Then I need to figure out what to do with my 36mm ZWO EFW and backfocus etc. I can see that it might not be so simple. With the Samyang, don’t I still need 55mm backfocus from the lens to the ASI2600? |
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Christian Bennich: Backfocus is 44mm for Canon EF. At f/2 you will also need to take into account any filter thickness. So, if you have a 2mm thick filter you'll want to add 0.667mm to the backfocus using shims, if possible. |
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Christian Bennich: No, the backfocus isn't dependant on your camera. The lens flange distance to focal plane is 46.5mm on any Nikon lens and will differ from other brands, Canon EF has 44mm etc. Backfocus is a property of the optics, 55mm just happens to be the industry-standard for a lot of flatteners/reducers etc. There will be differences between telescopes as well, my Edge 800 and Esprit 100 has very different needs for backfocus. |
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| Thanks guys. I love this - it’s a learning experience 🤪🤪 |
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| I see you ordered the Wega kit. Be sure to test it quickly within the return window. I‘ve had 2 out of 2 Wega parts fail. This has been some time, so maybe they moved to a different procedure since then. |
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Torben van Hees: Thx @Torben van Hees, great info. Any particular part that was more prone to failure? |
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| They were focuser attachments for an EAF. For the 135mm I have the Astrodymium kit which came with metal bolts and metal inserts instead of plastic threads. Pity it‘s not available any more, that was quite sturdy and has held up several travels (unfortunately only to cloudy places). |
