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Imaging with the Samyang 135mm f2


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55 minutes ago, Phillyo said:

are most of you shooting with this lens wide open or are you stopping down?

Hi Phil,

I use a 49mm step-down-ring which brings the aperture down to ~f2.63. I found that stopping the lens down produced better corner stars but I didn't like the diffraction patterns that were then apparent around the stars! The 77-49 mm step-down-ring is a good cheap alternative  :)

Adrian

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20 minutes ago, Adreneline said:

Hi Phil,

I use a 49mm step-down-ring which brings the aperture down to ~f2.63. I found that stopping the lens down produced better corner stars but I didn't like the diffraction patterns that were then apparent around the stars! The 77-49 mm step-down-ring is a good cheap alternative  :)

Adrian

Hi Adrian, yeah I use step down rings to 39mm which I think is about f3.4(ish). I never liked the diffraction spikes either.

Phil

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Astrodymium Ring Kit for Samyang 135mm Lens

First my apologies if this is in the wrong section but a thread so frequently visited by imagers using the Samyang 135mm lens seemed the appropriate best place. 🙂

This season I will be moving from my modified Canon 700D to using an ASI533MM-Pro as the main imaging camera coupled to my Samyang 135mm lens.  I intend using Astronomik Ha and OIII filters with a ZWO to EOS filter drawer arrangement and while having read that both Astronomik vanilla and Max FR filters are parfocal I expect to have to refocus between filters, I'd like to be wrong. Do any members have experience with this parfocal claim?

Expecting to have to refocus I have spotted the Astrodymium ring kit sold by FLO-

https://www.firstlightoptics.com/adapters/astrodymium-ring-system-with-zwo-eaf-asiair-mount-for-samyang-rokinon-135mm-f2-lens.html

Before placing an order for the ring system and ZWO focuser unit I would be pleased to hear from any other users of this kit so I can go into things with my eyes wide open.

Hope members will be able to help.

Cheers,

Steve

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54 minutes ago, SteveNickolls said:

I intend using Astronomik Ha and OIII filters with a ZWO to EOS filter drawer arrangement and while having read that both Astronomik vanilla and Max FR filters are parfocal I expect to have to refocus between filters, I'd like to be wrong. Do any members have experience with this parfocal claim?

I use 2" Astronomik L2, Ha and SII filters and a Baader OIII - which one day I will replace!

The last time I imaged LHOS I recorded 28893, 28868, 28558, 28872 from the EAF. Obviously the absoloute values are for my system alone but taking Ha as a reference the differences/offsets from Ha are 25, 0, -310, 4 so I would suggest that the Astronomik filters are very close to being parafocal when used with the SY135. The Baader, being 2mm thick as opposed the 1mm thick Astronomik, is clearly way off parafocal (as one would expect) resulting in the focus reference point on the lens being ~2mm before the 'L' on the lens. I hope that all makes sense. :)

As an aside I use 1.25" Astronomik NB filters on my RedCat with the ASI1600+EFW+EAF and the LHOS offsets w.r.t. Ha are 0, 0, 45, 5.

HTH

Adrian

Edited by Adreneline
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Thanks Adrian for your focus settings, I'm new to precise, repeatable focus values having previously focused manually. A difference in Ha and OIII of 10 sounds quite close to one another. Perhaps I would be best to see what results I get simply when changing filters before adding a remote controlled focuser?

Cheers,

Steve

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21 minutes ago, SteveNickolls said:

Perhaps I would be best to see what results I get simply when changing filters before adding a remote controlled focuser?

Good plan! I managed for a while with manual focus and a BM but found it very difficult to perform very small, incremental movements of the focus ring manually - the move to an EAF was definitely very beneficial. I've only recently started to use autofocus with the ASIair (and NINA with the RedCat) - and I still sometimes check with a BM.

I reckon you could probably set the focus at a median point and the results would be perfectly acceptable for all three filters.

Good luck!

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On 30/07/2022 at 11:12, SteveNickolls said:

Astrodymium Ring Kit for Samyang 135mm Lens

First my apologies if this is in the wrong section but a thread so frequently visited by imagers using the Samyang 135mm lens seemed the appropriate best place. 🙂

This season I will be moving from my modified Canon 700D to using an ASI533MM-Pro as the main imaging camera coupled to my Samyang 135mm lens.  I intend using Astronomik Ha and OIII filters with a ZWO to EOS filter drawer arrangement and while having read that both Astronomik vanilla and Max FR filters are parfocal I expect to have to refocus between filters, I'd like to be wrong. Do any members have experience with this parfocal claim?

Expecting to have to refocus I have spotted the Astrodymium ring kit sold by FLO-

https://www.firstlightoptics.com/adapters/astrodymium-ring-system-with-zwo-eaf-asiair-mount-for-samyang-rokinon-135mm-f2-lens.html

Before placing an order for the ring system and ZWO focuser unit I would be pleased to hear from any other users of this kit so I can go into things with my eyes wide open.

Hope members will be able to help.

Cheers,

Steve

If the light has passed through glass, each filter needs to be refocused to maintain optimum focus and/or field flatness over the largest area possible. This is true of any lens or refractor.

Ive found the only time parfocal actually works is through a newt, with no corrector in place. Because the only thing the light has hit on the way to your sensor, is a mirror.

I wouldnt worry about it too much for now, since youll be having so much fun in Ha ;)

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Haven't used the Samyang for a while now. I figured it was time for some widefield with the travel rig! I've never properly photographed the Sadr region, so that's my target for tonight. ASI2600MC-Pro and Antlia ALP-T is a nice combo, but I haven't tried it with the Samyang, so let's see!

I think my back spacing needs some tweaking... I'll analyse the corners tomorrow. Also my stars aren't as tight as I hoped, but that's probably because I'm imaging at f/2. I've run the AF twice now but the stars are stil 2.11 on average. I guess I won't do better at f/2.

What aperture are you guys using? Step up rings or the built in diaphragm?

 

image.thumb.jpeg.de17d33cee706d4f64033400d8a24fc9.jpeg

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  • 2 weeks later...

Another Summer Veil nebula complex. Samyang 125 at f2.8 paired with zwo asi 183 mono at gain 111, offset 15, & temperature -2 degrees. Ha 15 x 240” & Oiii 15   240” plus calibration frames. Unfortunately, lack of clear skies restricted imaging to just a single session - I was hoping for a lot more data. 

E6038612-503A-4B3F-AEFA-C2704C328BDB.jpeg

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16 hours on the North American nebula in 4min subs (some added from last year) through the Samyang 135 at F3.6, ASI533, Antlia ALP-T filter. 

I'm still getting some auto focus issues but hopefully I can iron those out soon. 

Phil

NGC7000.jpg

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And here is another one from the last 3 nights, under a full moon (not much blue/OIII data captured so might add more if time allows). This is a first to me, SH2 119. Situated just to the 'left' of the NGC7000 image I posted above but processed differently. This is about 8hours of total data with the Samyang, Antlia 5nm, ASI533, EQ6r Pro.

It's a beautiful target so I'll be interested to get more data on it for sure. 

I'm now wondering if I should go with a mono setup!! Bloody astrophotography always making me want to spend more money lol. 

Thanks for looking,

Phil.

SH2 119.png

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4 minutes ago, Phillyo said:

I'm now wondering if I should go with a mono setup!! Bloody astrophotography always making me want to spend more money lol.

Why wouldn't you want a second SY135+ASI533MM+EFW sitting alongside your SY135+ASI533MC? It's only natural ;) 

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1 minute ago, Adreneline said:

Why wouldn't you want a second SY135+ASI533MM+EFW sitting alongside your SY135+ASI533MC? It's only natural ;) 

Sadly I would definitely sell the OSC to get the mono. Although, I could use the OSC for star colours and the mono for the narrowband imaging I guess....hmmmm  🤔🤭

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It's been nearly two years since acquiring my Samyang 135 but have since only played around with it in combination with my modded 550D DSLR.  Whilst impressed with the results, my main objective was always to combine it with my ASI1600 mono camera but as that was tied-up with my main William Optics rig it just didn't happen, until now.  After upgrading to the ASI294MM Pro in May, at last I was able spend the early part of summer working on the aforesaid Samyang 135 + ASI1600 rig and now astro darkness is (just) back managed to catch a vfew photons of the Cygnus Loop with the new set-up. 

I had originally purchased a x2-ring Astrokraken 3D-printed clamping system for the lens + DSLR combination from Philippe but since then he's tweeked the design and, in particular added x3 M4 built-in nuts on either side of each ring for attaching ancillary equipment, which for me has been a game changer.  I therefore bought a new x3-ring Astrokraken bracket, with the said bolt holes, around which to build my new rig.  The bracket already allows a guidescope to be fitted immediately above the lens and with the third ring holding the camera firmly behind but now I've also been able to add an RDF on the left side to assist with navigation and framing, all nicely bolted onto a Losmandy plate which makes handling and storage easier.

Whilst the recent heatwave produced clear skies, it was not ideal for astronomy, furthermore hampered by a full moon.  However, with just over two hours integration time and only a few darks calibration, I'm still very impressed with the outcome of this quite amazing lens.  For me context is everything, so I just love the FOV and can't wait for better conditions, greater integration and more widefiled targets to point this wicked little lens at.

Graham

Samyang 135 f2.8 + ZWO ASI1600MM-Cool

Ha 27 x 180s

OIII 20 x 180s

Total: 2h 21m 

 

 

 

                  

Cygnus Loop August 2022 (Medium).png

IMG_20220810_191040466 (Medium).jpg

IMG_20220810_191107551 (Medium).jpg

Edited by groberts
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Planning to go for M31 this full moon, weather permitting. My usual setup is the Samyang 135 at f.8 paired with a zwo asi183 mono. Going to use broadband LGRB filters. I’ve been pondering the following and not found any consistent answers - hence this post.

1) Best to stay stopped down at f2.8 or go wide open at f2?

2) Possibly related to 1), best to image L as well as RGB or just to image RGB?

3) Multiple exposure times for L and other filters or one exposure time, keeping the gain low, to avoid blowing out the core?

At present, I’m thinking of going f2.8 and imaging  all filters at 90" (gain 56), including L, and balancing total integration time of L with RGB. But open to alternative suggestions. Not found many examples of M31 efforts with the Samyang 135 and a mono camera and so tips/advice would be greatly appreciated.

 

 

 

 

Edited by woldsman
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On 22/06/2022 at 09:12, aleixandrus said:

Hi! Well, it took a while but I managed to read all the 42 previous pages of this mega-thread :) There is a lot of very valuable information. Most of the notes I took were related to the mechanical assembly as it was the first problem I had to tackle. Now, I'm checking for narrowband filters. What I found is many of you just simply use 'conventional' filters but others use 'CMOS optimized' filters or even 'High Speed optimized' filters for f2-f4 scopes (such as the Baader High Speed 6.5nm Narrow Band Filter - CMOS Optimised). No consensus here.

I have an ASI183MM Pro and I don't plan to go crazy with 3nm filters but 6.5nm or even 12nm wide. I guess the wider the band is the less important redshift is. I also plan to add other scope in the future but as it will be slower (it's hard to go faster than f2!), I don't want to buy an additional filter set. How critical is redshift for this lens? Should I go for 'high speed' filters or may I go with 'conventional' ~12nm or ~7nm filters? In your experience, is there any specific filter or brand I should run away from? I want to buy once, but buy well.

Thanks a lot!

Hi! Resuming my 'old' question, I think I'll go with the normal 6.5nm Baader narrowband 31mm filters. I was reading the "Narrowband Filters on Astronomical Telescopes" white paper from Baader and I concluded that, as the 'normal' narrowband filters are rated for >f3.4, they should be fine (although not ideal) for f2.8, the f-ratio I plan to use.

My future scope will be slower than f4 for sure (some type of 400-600mm f4-f6 APO, probably) so I can use those filters. Going 31mm will be future proof for a ASI294MM or similar (I don't plan to increase sensor size). I live in a bortle 4-5 area although in the middle of the town. I think it doesn't make sense go 3.5nm filters.

I also considered the Astronomik ones with MFR coating, as they claim to work up to f3 (12nm) and up to f4 (6nm). The Astronomik MaxFR filters claim to work f1.4-f8 (12nm) and f2-f8 (6nm). However, they are almost 2 times more expensive than the Baaders and they don't seem to be twice as good so... Being poor is a doom 🥲

What do you think? May I regret this decision?

 

PS: These links are available in previous posts but worth posting them again:

PS2: A combination of bad weather, busy calendar, mechanical issues trying to get optimal backfocus and the inevitable learning curve including NINA forced me to take me this hobby slowly 😅

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On 21/08/2022 at 20:40, woldsman said:

Planning to go for M31 this full moon, weather permitting. My usual setup is the Samyang 135 at f.8 paired with a zwo asi183 mono. Going to use broadband LGRB filters. I’ve been pondering the following and not found any consistent answers - hence this post.

1) Best to stay stopped down at f2.8 or go wide open at f2?

2) Possibly related to 1), best to image L as well as RGB or just to image RGB?

3) Multiple exposure times for L and other filters or one exposure time, keeping the gain low, to avoid blowing out the core?

At present, I’m thinking of going f2.8 and imaging  all filters at 90" (gain 56), including L, and balancing total integration time of L with RGB. But open to alternative suggestions. Not found many examples of M31 efforts with the Samyang 135 and a mono camera and so tips/advice would be greatly appreciated.

I am not the most appropriate to give advice but:

  1. Going f2.8 is safer than f2. I have some tilt and backspace issues with that same setup at f2 which are less pronounced at f2.8 (check post here).
  2. As far as I know, LRGB is superior to RGB even with mono cameras. I think L subs are more important than RGB subs as luminance tends to be more important than color.
  3. It depends on the camera characteristics and light pollution. You may expose as longer as possible the LP (and mount) allow you. Unity gain is usually the recommended starting point, tweaking the exposure length and/or gain as needed based on environmental conditions and equipment. Then, stack as many frames as possible. In addition, if the scene has more dynamic range than the camera support, take other series of stacks with shorter exposure and/or gain. You can blend the two final stacks (I did this before with my DSLR and Photoshop, never with PixInsight, DSS or other astro software). Not sure if this is necessary with M31 if you exposes carefully, by the way.

Please, anyone, feel free to correct any of my comments! I probably made some mistakes but, as @woldsman has any answer yet, I tried my best 😅

BTW, I shoot M31 with the Samyang 135 but using an unmoded Sony a7III... Not sure if that experience may help you, but feel free to ask.

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I did this for m31 but with a colour camera:

Imaging luminence will make a difference to the final RGB image as that's where most of the sharper detail will come from, I find it is also less noisy than any R, G, B stack.

Regarding time for exposure, this will greatly depend on your local conditions, if it's free of light pollution you can go longer but there is a point of diminishing returns. Better to take shorter and stack many to average out any noise, and dither often.

 

 

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On 24/08/2022 at 17:23, aleixandrus said:

I am not the most appropriate to give advice but:

  1. Going f2.8 is safer than f2. I have some tilt and backspace issues with that same setup at f2 which are less pronounced at f2.8 (check post here).
  2. As far as I know, LRGB is superior to RGB even with mono cameras. I think L subs are more important than RGB subs as luminance tends to be more important than color.
  3. It depends on the camera characteristics and light pollution. You may expose as longer as possible the LP (and mount) allow you. Unity gain is usually the recommended starting point, tweaking the exposure length and/or gain as needed based on environmental conditions and equipment. Then, stack as many frames as possible. In addition, if the scene has more dynamic range than the camera support, take other series of stacks with shorter exposure and/or gain. You can blend the two final stacks (I did this before with my DSLR and Photoshop, never with PixInsight, DSS or other astro software). Not sure if this is necessary with M31 if you exposes carefully, by the way.

Please, anyone, feel free to correct any of my comments! I probably made some mistakes but, as @woldsman has any answer yet, I tried my best 😅

BTW, I shoot M31 with the Samyang 135 but using an unmoded Sony a7III... Not sure if that experience may help you, but feel free to ask.

Thanks for the advice. technically I live in Bortle 4 but I don’t rate it quite as good as this. f2.8, Luminance & 90 second subs seem the way to go and I’ll try them for my first effort.

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On 24/08/2022 at 17:53, Elp said:

I did this for m31 but with a colour camera:

Imaging luminence will make a difference to the final RGB image as that's where most of the sharper detail will come from, I find it is also less noisy than any R, G, B stack.

Regarding time for exposure, this will greatly depend on your local conditions, if it's free of light pollution you can go longer but there is a point of diminishing returns. Better to take shorter and stack many to average out any noise, and dither often.

 

 

Thanks for the great advice! Will experiment & report back. Had a problem with my EAF focuser but that is now fixed. Weather tonight is not good but I hope to test back focus as have fitted a slim rotator. All being well, Saturday could be the night if the forecast turns out to be correct and I can get stars in the test run. 

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44 excellent pages to read, quite some amazing shots taken with that lens. Anyway, I've spotted someone (@mAnKiNd) using an OAG but that user hasn't visited this forum since October 21, 2021... Would anyone else using an OAG with that lens by any chance?

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