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I was interested in acquiring a Samyang 135mm f/2 (or Rokinon) to do widefield deep sky imaging. I apologize if the following questions are repetitive. It is my interest to not use a DSLR, since I do not own one that I am willing to astro modify, yet I do have a ZWO C-sensor cooled RGB camera already and will likely get a similar mono camera (hopefully full-frame) in the near future. When I research the lens, it usually is listed with a camera brand regarding native mount connectivity. Do I just pick one for any brand camera and then get an adaptor that would allow for screw on filter changer, astro camera etc? I will worry about mounting rings and the like later, once I know what the imaging train will look like. When using an astro camera, will I have serious back focus issues regarding the addition of filters, etc? Can someone on this forum point me to the resources needed to do this with the gear I am expecting to use. Or give me advice if I am going in the wrong direction? Again much appreciated and sorry if this is an old topic. |
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Hi, I have the Canon version of the Samyang 135mm f/2 lens and use it with my ZWO ASI294MC Pro. For adapter I use this one: https://www.firstlightoptics.com/zwo-accessories/zwo-adjustable-eos-lens-to-t2-adapter-for-all-asi-cameras.html Inside the adapter you can fit standard 2" filters. The adapter is designed to give you the correct back focus with ZWO cameras. Cheers, Johs |
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And for mounting, I use this one: https://astronomy-imaging-camera.com/product/new-holder-ring-for-asi-cooled-cameras78mm-diameters There's also this one, for the larger diameter cameras: https://astronomy-imaging-camera.com/product/holder-ring-for-asi-cooled-cameras86mm-diameters |
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Hello Alan, According to my understanding, you need to select a camera type for the Samyang/Rokinon 135mm, such as Nikon, Canon, Sony... then you can use an adaptor for that camera brand such as offered by ZWO here: https://astronomy-imaging-camera.com/product-category/accessories A tailored adaptor will also get the camera into focus which is important as the lens' focus travel is not as long as that of refractors. Though you are not planning to modify your DSLR, I would go for its connector, you never can tell 😉 I have got the Samyang 135mm for my Nikon D5500, no regrets whatsoever. Cheers Robert |
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| https://agenaastro.com/zwo-filter-drawer-for-canon-eos-lens-fd-eos.html Hi Alan, I use the Zwo 071 mcpro. This adapter has a built-in filter drawer. Making it so much easier to switch the filters. I bought 3 drawers, just pop in the different drawer to switch from my Uvir filter to my L-Extreme. Plus, Agena ships the same day. |
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Last time I looked, eBay prices were a bit lower for Canon models (compared to Nikon). If still the case, go for a Canon model and adaptor. Canon fitting are probably the most common. Good luck! |
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| Thank you all for the suggestions. Each is very helpful to me! |
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One remaining question from all the responses is if the adaptors suggested would allow the use of a full frame sensor? I know the lens itself is set up to do so within the context of the matched DSLR, but I am not sure if any of these adaptors, with given back focus, will achieve that without vignetting. But I am not necessarily asking for perfect, just hoping to be able to use a full-frame sensor at some point, even if there is a little vignetting that can be handled with flats. I need to say that I have only looked at the Agena and FLO adaptors because the ZWO web site appears to be dead today for anything beyond their home page. So the ZWO links from Johannes and astropical may well hold the answer to my Full-Frame questions. I will recheck with ZWO when they come back on line. |
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| Hi Alan. Yes, they work out to full frame but star artefacts occur towards the edge when used wide-open. No so noticeable when stopped down to about f/2.8. Hope that helps. |
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I have have the Nikon version (as Rokinon). I've tried both zwo Nikon adapters (the lower end one and the version with the filter drawer) on my asi533mc pro, and they both have serious tilt issues. I've seriously given up on the combination for now while seeking a better mounting option. If you get a choice between Nikon and Canon versions, get the Canon version. There is an after-market part that replaces the Canon bayonette mount with a m48 thread, and it has a MUCH better fit. See the discussion here: https://astrojolo.com/gears/thirty-months-with-samyang-135-f-2/ I believe this is the adapter: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html |
