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| Any general observations on the Rokinon 135...how good is it? What other lens performs as well as the Roki? |
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I really really love my Samyang/Rokinon 135mm. It was a huge boost to my AP, because I am now at least 10 times faster in acquisition copared to my last tele lens. It is so sharp that you can compare it with cheaper 200mm lenses regarding resolution. Sometimes I use it at f/2, just for the speed, but I recently tend to use it at f/2.8 to get slightly smaller stars. All I can say is that it is an amazing addition to my mobile setup and nicely works on the Star Adventurer. |
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I have both a Rokinon 135 and a couple Canon 135s. I like both of them but have not done a formal test to compare the two. I do tend to use the Canon 135s more often. I haven't tried the Zeiss 135mm but I have read some tests that this may be the best 135mm lens out there. Honestly, I think that you are going to be happy with any of these three (unless you want autofocus for regular photography). That being said the Canon 200mm f1.8 lens is my favorite lens to use. I just got the new version (200mm f2) but haven't tried it yet. |
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| I have heard a lot about this lens, can anyone provide a sample single unprocessed (RAW if possible) shot at F2 with full frame DSLR camera or similar sized CCD. |
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Hi Bill...this is a randomly selected single 5 minute, unguided, luminance exposure with a QSI583 at -15C + Rokinon 135mm operating "somehwere between" f/2 and f/2.8. Image scale is ~8" / pixel. The data respond well to drizzle integration. Off axis performance is quite good. I've analyzed data from this combo every which way I know how and it measure up pretty well. More importantly to me is it processes well. The most notable issue for me is the vignetting which comes out well with flats and DBE. Btw, when I use DBE on this data is is usually just 2-4 samples in each corner...sometimes fewer. Thoughts? Sample Frame from Rokionon 135 + QSI583 This is the fully processed image: Widefield M31 LRGB |
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The images look very good at about APS-C (QSI583 is just a tad smaller). Thanks. Now I have something to compare with the Zeiss 135 f2 APO sonar T*, but I think the Rokionon appears to be much better. My opinion is just from memory of seeing ice cream cones for stars at f2 in the corners of a full frame camera (D810A). Unfortunately I did not save the images. Waiting for some clear skys to shoot some samples. |
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| Hi Bill...glad this helped. I continue to be impressed with the lens and am looking forward to a good winter season. I've had it up and running at DSW since just before the summer rains and have gathers ~140 hours already across 20 targets, 11 of which are complete. |
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| I use Canon 200mm f/2.8L IS USM ll and Samyang (Rokinon) 135mm f/2. I was inspired by the Lloyed's images to purchase the latter. The lens gives me very sharp stars at F/2, but my unit appears to have a slight misalignment of the optical axis in the lens or in the lens-camera adapter, resulting in blurred/elongated stars along one edge of the field. This may indicate some QC problems (I did try to adjust for the sensor tilt). Both Canon and Samyang/Rokinon lenses give me very good narrow-band frames too, but the S/R's F/2 light cone would be too steep for 3nm-6nm filters due to the spectrum shift (I use an aperture mask to tame it to F/2.8). Canon at F/2.8 gives me superb images in narrow band, but RGB images are not as sharp due to its rather severe CA. I would stop it down to F/4 for that (Rokinon/Samyang does not seem to have this problem). |
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| You can still give your narrow bands a try. Behind the lens the cone angle is more related diameter of the last element and distance to sensor than the front aperture. |
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| I've used 5nm Ha (Astrodon) with no issue. I haven't done the others simply because the camera only has 5-position filter wheel. The system is remote which makes it tough to switch out ;-) I could have the local tech do it, but for now Ha is good enough. |
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Check out a Nikkor ED 180mm F2. Best lens in this range I've ever used. https://www.flickr.com/photos/45984738@N03/27804898140/in/datetaken/ |
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| Can you post a link to a raw frame? I'm curious how well it does across the entire frame. I'd like to get a range of lens to cover different fields of view. For now the 135 Roki (effective 127mm on my rig is very good. Would be nice to find a good performer at 200mm at a reasonable price. The Roki is < $500 |
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Lloyd: If you mean me I can confirm that even with a full frame DSLR the Nikkor ED is super sharp corner to corner. The link I posted is a single exposure just slightly cropped and only basic editing done in RAW. They can be found for under $200. Highly recommended! |
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Lloyd: Have you thought about just using different sensors with different sized pixels instead of different lenses? |
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| Not a bad idea. Getting different lenses is a bit on the more economical side than new cameras though. Still something worth considering. |
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Lloyd: Yes, more economical depending on the cameras you use... Maybe a wash with some other brand cameras. I'll keep you posted on experimentation and testing due to start in the next week or two  |
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| True indeed. Talk to you soon. Good luck. |
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| Will the Rokinon come to focus with the QSI WSG? Or is the WS version required? |
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Hi Lloyd, I wonder how you can solve the tilting problem. I use rokinon135mm + QSI690ws + QSI EOSmout adator + QSI autofocusing bracket. I think the QSI EOS adapter have some wobble, and because the timingbelt on the bracket always pull the lense there should be tilting problem. Can you show me the image of you system? |
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I use a single telescope ring to stabilize the system that keeps the belt from pulling the system. I also make sure the belt it not too tight. One other thing that should be tested is the frequency of focusing needed for this lens and your system. I have yet to determine definitively, but I believe the Rokinon is relatvely insensitive to temperature change. Assuming this is true then two things come to mind:1) focus is infrequent and thus will pull on the lens infrequently, 2) imaging does not occur during the focusing process. So if there's tilt, then I question whether or not the belt is the source while imaging. It could be the source if it's generally too tight, or it the lens is not otherwise supported as in the case with a ring. http://deepskywest.com/rokinon_astrophotography/ |
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I don't know how much wobble there is but if it wobbles under the lenses weight it is to much unless you are shooting at the zenith. you will need to add support like Lloyd has. If you are handy you can tighten the lens adapter by bending the leaf strings underneath the flange on the camera side. Assuming your model has them. Nikon mounts have them at least the ones I dissembled. Question does rokinon135mm have internal focus? |
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Thank you Lloyd and Bill. I'll try loosen my belt and add mount ring to hold my lens. Bill I already bending the leaf sting so there are so little wobbles. but there are still elongated stars up-right-side of my image. Because my focusing motor located at down-left-side of my lens, I think it may caused by belt-driven system. Rokinon does not have internal focusing motor so I use the system. |
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I think it's the best lens for all astrophotography beginners. It's cheap , sharp, has low CA and has an newbie friendly focal length. No big mounts are needed, no guiding needed. There may be some QA issues, but I guess I was lucky with my piece. My findings: - In case of T2 adaptation a proper distance is crucial ,especially for shorter wavelenghts (OIII) - Going for f2.8 may help to increase the quality. - The lens seems to hold focus pretty good The Samyang/Rokinon lens is a great piece of hardware. I would buy it all over again. |
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I think it's the best lens for all astrophotography beginners. It's cheap , sharp, has low CA and has an newbie friendly focal length.No big mounts are needed, no guiding needed. I couldn't agree more! We have it on a PME which I should clarify: the mount is definitely not required for good images. It happened to be unused at the time. I will go up to at least 10 minutes unguided in this way over-mounted configuration, but even a modest mount will do well at such a short FL. Overall, very highly recommended "starter scope". |
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Minseok.Chang: Sorry for the confusion, does the Rokinon lens move in and out when you focus or remain fixed? If the lens does not move then you need to achieve focus near infinity indication for the best imaging field |
