Imaging with the Samyang 135mm f2

[StamosP]

6 hours ago, Adreneline said:

I can't help but feel that if this is your infinity focus position then the spacing is incorrect - probably by a fraction of a millmetre. When my stars are in focus the centre mark is right in the middle of the base of the 'L' mark which in my understanding is where it should be. Modern lenses will focus "beyond infinity" so you should not be looking to align the centre mark beyond the 'L' toward the infinity mark either. It took lots of trial and error for me to find the correct spacing and even then inserting/removing a 0.15mm spacer would throw the whole thing out.

Even once I achieved the correct spacing the star shapes in the extreme corners were not perfect compared with the centre of the image; I guess it all comes down to just how good the optics are in your particular lens. Astrophotography makes demands on focussing that are never/rarely required in regular everyday photography.

Good luck.

 

Thank you very much, this was indeed my infinity focus position during testing

Did you notice any significant improvement when you nailed down the distance?

Yesterday i did some experimentation from my balcony to see whats wrong with the distance, no mount at all, i just held the lens-camera in my hands as steady as i could.

Thankfully Venus made the process very easy and in 5 minutes i found that i had to add exactly a 0.5mm spacer (i also tried 0.2-0.4-0.6mm) to achieve infinity focus exactly at the vertical line of L.

 

Edited April 20, 2020 by StamosP

[Knight of Clear Skies]

Here's a final(ish) version of Simeis 147 in RGBHa.

This is about 8 minutes per channel in LRGB and 50 minutes in Ha with the 1600MM cool, on the Star Adventurer mount.

 

The nebula really stands out in the Ha version.

Not a difficult target at f2 from a dark site but keeping the blizzard of stars under control wasn't easy.

[Adreneline]

31 minutes ago, StamosP said:

Did you notice any significant improvement when you nailed down the distance?

Yes, but the greatest improvement was in the peripheral stars in the extreme corners of the image - there was no real discernible difference for stars in the central region. As you are finding even tiny changes in spacing make a huge difference to the focus position. It is worth the effort in the end.

Good luck.

Adrian

[StamosP]

On 20/04/2020 at 20:25, Adreneline said:

Yes, but the greatest improvement was in the peripheral stars in the extreme corners of the image - there was no real discernible difference for stars in the central region. As you are finding even tiny changes in spacing make a huge difference to the focus position. It is worth the effort in the end.

Good luck.

Adrian

I hope i will see that improvement too, thanks a lot Adrian!

 

I have performed some tests to see what happens to the field illumination when the lens is stopped down.

The first pic is with the lens wide open, the mean adus were about 30.000. The second one is with the lens stopped down at f2.8 by using the internal diaphragm and the last one by using a 48mm step down ring (equivalent to ~f2.8) in front of the lens. Both of these images have a ~18.000 mean adu value. 

All the images have been autostretched in pi, the last two have exactly the same stretch to make them comparable

Edited April 21, 2020 by StamosP
smaller images

[Adreneline]

3 hours ago, StamosP said:

All the images have been autostretched in pi, the last two have exactly the same stretch to make them comparable

Interesting. Not sure why there appears to be banding in the second image. The last one looks pretty comparable to my flats. Which filters are you using?

Adrian

 

[Space Oddities]

I think the banding is due to the light source used when these images were taken. It's a common issue with rolling shutters, as explained here: https://enthusiastphotoblog.com/silent-shutter-banding/

Edited April 22, 2020 by Space Oddities

[Helen]

My adapter arrived to day... off to find a little screwdriver for some micro-surgery 😉  and find my filter wheel/changer.  I'm (trying to decide whether to go mono or colour camera on the back, but I'll need a light pollution filter whatever - last night I tried some widefield from my garden with the Sony 6500 and the samyang 12mm and the light polllution was terrible 😞  

Helen

[StamosP]

Yes, this banding has to do with some kind of flickering and the camera's shutter, i rarely see it and i didn't bother to recapture the frame as i was only interested in the vignetting.

I had the suspicion that the ring will cause vignetting but i had not performed any back to back tests until now.

There is indeed a significant amount of vignetting when the lens is stopped down by using the step down ring so i think the best approach is to close it by using the internal diaphragm (even though this will cause diffraction spikes).

 

[Helen]

1 hour ago, Helen said:

My adapter arrived to day... off to find a little screwdriver for some micro-surgery 😉  and find my filter wheel/changer.  I'm (trying to decide whether to go mono or colour camera on the back, but I'll need a light pollution filter whatever - last night I tried some widefield from my garden with the Sony 6500 and the samyang 12mm and the light polllution was terrible 😞  

Helen

Ah, can't find a small enough screwdriver 😞  and can't pop to the local diy for one...

 

[ApophisAstros]

I have the rings and micro focuser from france and a Atik460ex mono but just could not find focus if i start with the focus (using the Bhatinov cap from france) at the L with the screws equally set ,  as advised, help would be welcome as i really want to get into widefield imaging,

Roger

[Adreneline]

19 minutes ago, apophisOAS said:

i start with the focus (using the Bhatinov cap from france) at the L with the screws equally set

Hi Roger,

You certainly want to achieve focus with the focus mark aligned somewhere in the base of the 'L'. The only way I have found to do this is to experiment with various spacer combinations to get the correct spacing. Nominally it should be 44mm but my experience is it is always more. You will find that even introducing a 0.2mm shim spacer will make a lot of difference to the focus position - it is very sensitive to getting the spacing correct, especially at f2.

I spent last night trying to marry up my Samyang 85mm to my Atik414ex-osc. After a couple of hours I decided to stop and have a go another night. I'm pretty close but I think I need another 0.15mm shim spacer which I don't have. Frustration! If I stop the lens down to more like f8 I can achieve focus but opening it up to f1.2 and I can't get focus within the limits of the 'L' mark.

It's all down to trial and error I'm afraid - and perseverance! 

Good luck!

Adrian

P.S. I use SharpCap FWHM whilst I'm getting things sorted - I'll use a BM once I've basically got it all sorted with the correct spacers/shims.

[Adreneline]

This is IC1396 and Sh2-129 in Ha - 4 hours 24 mins of 180s exposures, unguided - all on the same night! 

Calibated and integrated in APP followed by ABE, HT, LHE and masked HDRM in PI and finally minimal noise reduction in PS ...

.. and annotated in PI

APP reported FWHM of less than 1.5 on every frame so quite pleased I've got focus and spacing pretty well sorted.

Just need the same amount of OIII.

Edited April 26, 2020 by Adreneline
Clarification

[Knight of Clear Skies]

Here's another effort with the Samyang f2 and 1100D, with clip-in filter.

And here's the result of blending this into an RGB image I previously took with a 135mm Takumar f3.5 lens (more details here.)

[Space Oddities]

Yet another heart & soul   30x300s (2.5 hours) at unity gain with the ASI1600MM-Pro and ZWO's 7nm Ha filter, from the comfort of my hotel room in the Austrian Alps. The room had a balcony that was conveniently oriented North and almost free of any obstruction. I took these back in January. No dark, flat or bias, but I'll add them later!

[Adreneline]

Despite only nautical darkness and  a 60%+ moon I was quite pleased with the end result from two short nights of imaging. The 135mm can certainly hoover up photons. All unguided 20 x 180s of Ha and OIII using the ASI1600-MM Pro.

Gamma Cygni region (edge cropping only):

Veil (cropped somewhat because the trees got in the way!)

Adrian

 

[Craney]

This lens is really something else.   

Over the last 3 nights or so I have been fighting a losing battle with the  C8Edge's focal length,  APS sized sensor, trying for RGB,  no astro-darkness, an ever increasing Moon and invading high cirrus.   Maybe leave it til August ??.   No, lets give the ol' 135mm a go.

So... reversing the bits I can control.    135mm Samyang, Atik 414ex (small sensor), Narrowband.   

This is with about 35mins on each channel and with an 85% Moon !!!!! and passing high cloud.   I'm very happy with that.

 

Sean.

 

[carastro]

Since being recommend this fantastic little lens by Vlaiv and backed up by Uranium I have been having a ball.  I can't quite get the star shapes right in one corner, but as I am at the limit of focus, I can't add any more spacers/ tilt adjusters into the system.  But not withstanding, I have done quite a few images from Bortle 8 since I got this lens just before lockdown.

 Jellyfish:  My first in HaRGB (must try this again with a smaller FOV camera and other NB colours.

Flaming star and Tadpoles, and also Spider nebulae

NAN and pelican in Hubble Palette with RGB stars

M42 and HH FOV test (not much data) HaRGB

Sadr Region Hubble palette and RGB stars

Elephant's Trunk nebula IC1396 Hubble palette and RGB stars

NGC7822 and Little Rosette Nebulae, Hubble palette and RGB stars 

 

 

 

[celeron787]

I just got the Samyang 135mm E mount for my Sony A6000 and am looking to get a sturdy tripod collar for the samyang 135mm.

Came across the Novoflex ASTAT-NEX collar which looks pretty good. The thing is there's a few different versions available.

1. https://www.bhphotovideo.com/c/product/758213-REG/Novoflex_ASTAT_NEX_ASTAT_NEX_Tripod_Collar_for.html/overview

2. https://www.novoflex.de/en/products-637/lens-adapters/adapter-collar-mounts/adapter-collar-mounts-products/ASTAT-NEX_en.html

The 2nd one is cheaper for me due to shipping cost, so I was wondering whether anyone have any experience with the fit of that exact collar with the samyang 135mm. Would love to see pictures of the fitting too!

Thanks!

[Uranium235]

On 22/04/2020 at 20:52, Adreneline said:

You certainly want to achieve focus with the focus mark aligned somewhere in the base of the 'L'. The only way I have found to do this is to experiment with various spacer combinations to get the correct spacing. Nominally it should be 44mm but my experience is it is always more. You will find that even introducing a 0.2mm shim spacer will make a lot of difference to the focus position - it is very sensitive to getting the spacing correct, especially at f2.

 

100% correct on all counts! (apart from its 44.1mm but im just being pedantic...lol)

Dont forget, when you add a filter between the lens and the camera - you need to take into account the amount of spacing you need to add (not subtract).

Astronomik: Add 0.33mm

Baader: 0.66mm

Astrodon: 1mm

 

Yes, it does matter about adding the spacing when working with an f2 lens because the filter thickness can throw infinity focus out quite a bit.

If you have a mix of filter brands in your wheel, then you need to come to a compromise spacing.

[Space Oddities]

7 hours ago, celeron787 said:

I just got the Samyang 135mm E mount for my Sony A6000 and am looking to get a sturdy tripod collar for the samyang 135mm.

Came across the Novoflex ASTAT-NEX collar which looks pretty good. The thing is there's a few different versions available.

1. https://www.bhphotovideo.com/c/product/758213-REG/Novoflex_ASTAT_NEX_ASTAT_NEX_Tripod_Collar_for.html/overview

2. https://www.novoflex.de/en/products-637/lens-adapters/adapter-collar-mounts/adapter-collar-mounts-products/ASTAT-NEX_en.html

The 2nd one is cheaper for me due to shipping cost, so I was wondering whether anyone have any experience with the fit of that exact collar with the samyang 135mm. Would love to see pictures of the fitting too!

Thanks!

I used the Novoflex one (Fuji X mount), and it's well made. It's surprising at first because the collar looks quite thin, but it holds the lens well. You can easily mount it to a dovetail bar or ballhead. The Arca Swiss base has 2 holes, 1/4" and 3/8".

I'm actually considering selling mine, as I'm now using the Canon version of the lens, which isn't compatible with the collar. Perhaps you're interested?

Here are a few pictures

[Craney]

Solstice Mosaic.     Cygnus gas clouds.

Amazing how little 'night-time' there is come mid-June.    I was aware of this patch of lighter sky over to the North East that just was not getting any darker., but it was the first clear sky in over 2 weeks. 

Narrow band was the way to go. Planets are just too low at the moment.

Mosaic.   Samyang 135 with Atik 414Mono.    Over the the 2 panes (top and bottom effectively)  about 30mins on each Ha, O3,S2.

[Laurin Dave]

North American and Pelican Nebulae in HOO with RGBish stars from Monday night.  90 minutes Ha and Oiii and 5 minutes each RGB.  Samyang 135 at f4, ZWO Nikon connector, EFW and ASI1600mm.  I just set it running at 11:30 and went to bed, consequently the Oiii was somewhat out of focus ...  "fixed" this with Starnet by removing the Oiii stars and replacing them with the Ha ones.  Also the ZWO connector isn't great (does anyone know of a better solution) and there's tilt (and most likely spacing) issues with the stars but apart from that I'm pretty pleased with the outcome.   Also of note is that for once there are no microlensing issues with the ASI1600.   

Thanks for looking 

Dave

 

Edited June 24, 2020 by Laurin Dave

[Space Oddities]

Splendid, Laurin!

You might want to take a look at the DSLR mount to M48 converters for the Samyang. @Uranium235 created one, sold by FLO: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html

There is also this version made by a Polish astronomer, which looks similar: https://shop.astrojolo.com/product/samyang-135-f-2-bayonet-threaded-replacement/

However, I believe the Nikon and Canon versions are different (4 screws vs 3 screws), and the adapters are only compatible with the Canon lens. But I'm sure you can contact Astrojolo or Uranium to see if a Nikon version can be made.

In the meantime, you could use another adapter for the lens. The one made by Geoptik has a good reputation compared to the ZWO, and there's a TS optics copy out there as well I think.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p2837_Geoptik-CCD-Kamera-Adapter-mit-T2-Anschluss-fuer-Nikon-Objektive.html

[Rob]

I think its staggering what you guys are capturing with these lenses.. great work

Edited June 25, 2020 by Rob

[Laurin Dave]

58 minutes ago, Space Oddities said:

Splendid, Laurin!

You might want to take a look at the DSLR mount to M48 converters for the Samyang. @Uranium235 created one, sold by FLO: https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html

There is also this version made by a Polish astronomer, which looks similar: https://shop.astrojolo.com/product/samyang-135-f-2-bayonet-threaded-replacement/

However, I believe the Nikon and Canon versions are different (4 screws vs 3 screws), and the adapters are only compatible with the Canon lens. But I'm sure you can contact Astrojolo or Uranium to see if a Nikon version can be made.

In the meantime, you could use another adapter for the lens. The one made by Geoptik has a good reputation compared to the ZWO, and there's a TS optics copy out there as well I think.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p2837_Geoptik-CCD-Kamera-Adapter-mit-T2-Anschluss-fuer-Nikon-Objektive.html

Thank you Pierre,  I got one of the screw adapters from Astrojolo then discovered it didn't fit , I shall investigate the Geoptik adapter.

Dave