Imaging with the Samyang 135mm f2

[Elp]

Think I've taken this too far...

[AMcD]

There is no such thing as "too far" in this hobby 😂

[powerlord]

This reminds me of the early 1990s when I was a student working at BT Research and Development Laboratories - they were working on a VR helmet - and back then it had CRTs in it and was very very front heavy causing people to quickly start walking around looking at the ground.

After a quick pow-wow with management foxed for a solution, and the more theoretical researchers worrying that to make it lighter would  be a total redesign and take years - a REAL engineer present said "give me 5 minutes and took the helmet away".

He came back with a 2kg lead weight glues onto the back of the helmet balancing it - job done. 😃

I can imagine this being the same - hmm.. it's not balanced with one DSLR and one camera and lens the other side.. what can be done - ah - add another camera and lens!

stu

Edited February 8, 2023 by powerlord

[Elp]

To be fair with the dslr on the left it's massively weighted in that direction, just tried it to see if it will fit, and with it it just about falls within the weight limit I usually use on this mount. I COULD fashion a counterweight to balance it (think of the triple imaging time!), but setting up two lenses from scratch is bad enough. So I've settled on the two lenses, so there's also room for two asiairs on the bar which balances well. I can also use the one lens if I want without reconfiguring the fixings. Now if I can get over the technical issues with the latest zwo update I can actually get on with imaging.

Edited February 8, 2023 by Elp

[powerlord]

What issues u having with yer asiair? Only ones I have are ones I've always had - main one being sometimes after a meridian flip on autorun it just sits there not imaging wasting the night. I've raised it finally with zwo.

[Elp]

It's that bad I actually started a thread:

https://stargazerslounge.com/topic/405385-asiair-software-update-20-1046/

 

[Space Oddities]

8 hours ago, Elp said:

Think I've taken this too far...

This is only the beginning, I'm afraid...

 

[Mr H in Yorkshire]

7 hours ago, Space Oddities said:

This is only the beginning, I'm afraid...

And that's just the bird watching rig, you should see the  AP setup.

[Laurin Dave]

Whilst not entirely acquired with a Samynag135 more than 80% was so thought it was ok to post here as well..  

Dave

 

[Laurin Dave]

Barnard's Loop, M78, The Belt and Sword of Orion, two panel mosaic with Samyang135 ASI2600mc, 4 hours per panel of 5 minute subs, gain zero, offset 76, lens at f2.8. Processed in Pixinsight and Photoshop, stars courtesy of Blur and Star Exterminators

Thanks for looking 

Dave

Edited February 19, 2023 by Laurin Dave

[Adreneline]

5 minutes ago, Laurin Dave said:

Thanks for looking 

Very nice Dave. You must be very pleased - your SY and 2600 are doing a great job. Very good star shapes and colours all the way to the corners so you've nailed the setup and spacing. So much to feast your eyes upon - great job. Thanks for sharing! Adrian

[powerlord]

1 hour ago, Laurin Dave said:

Barnard's Loop, M78, The Belt and Sword of Orion, two panel mosaic with Samyang135 ASI2600mc, 4 hours per panel of 5 minute subs, gain zero, offset 76, lens at f2.8. Processed in Pixinsight and Photoshop, stars courtesy of Blur and Star Exterminators

Thanks for looking 

Dave

lovely. best I've seen.

[gorann]

3 hours ago, Laurin Dave said:

Barnard's Loop, M78, The Belt and Sword of Orion, two panel mosaic with Samyang135 ASI2600mc, 4 hours per panel of 5 minute subs, gain zero, offset 76, lens at f2.8. Processed in Pixinsight and Photoshop, stars courtesy of Blur and Star Exterminators

Thanks for looking 

Dave

It is just outstanding what that little lens (with you behind it) can do in such a short while!

[Laurin Dave]

17 hours ago, Adreneline said:

Very nice Dave. You must be very pleased - your SY and 2600 are doing a great job. Very good star shapes and colours all the way to the corners so you've nailed the setup and spacing. So much to feast your eyes upon - great job. Thanks for sharing! Adrian

 

Thanks Adrian..  Blur Exterminator does a marvellous job with the stars, I have the Nikon version of the lens so it's connected via one of ZWOs adapters which has  degree of slop in it. Love the speed though and all the dust it brings out even from my Bortle4-5 skies.

16 hours ago, powerlord said:

lovely. best I've seen.

Very kind of you  

14 hours ago, gorann said:

It is just outstanding what that little lens (with you behind it) can do in such a short while!

Thanks Goran.  it was seeing you hoovering up photons like nobodies business with your RASA and colour camera that re-invigorated my use of this lens plus Russ Croman's apps which sort out the stars

[Laurin Dave]

M81 M82 surroundings and the IFN.  17 hrs of 300sec subs at gain 0 offset 76 through Samyang135 at f2.8 and ASI2600mc all gathered whilst I was asleep  .  Processed in Pixinsight and Photoshop using Normalise scale gradient, and Rus Croman's Blur,  Star and Noise Exterminators.  Hi res data overlaid over M81 and M82 to give them a bit of colour. 

Thanks for looking

Dave

 

 

Edited February 21, 2023 by Laurin Dave

[AstroMuni]

2 minutes ago, Laurin Dave said:

M81 M82 surroundings and the IFN.

You are on a roll Dave 🙂 Yet another great image

[Space Oddities]

Superb! Love the IFN!

[SAW]

I'm still struggling to get nice stars in the corners especially on the right hand side. 16x300s Ha with the 2600mm at f/2.8. Any tips to get better stars at the edges ? No calibration frames used !

Edited February 26, 2023 by SAW

[Adreneline]

10 minutes ago, SAW said:

Any tips to get better stars at the edges ?

I guess you've already done this type of thing with ASTAP, which is indicating mild tilt:

.. or with Siril, essentially consistent with ASTAP but a 'cleaner' display:

I messed around for ages trying to eliminate tilt on my setup - I seem to recall getting down to 6% in the end. I ended up supporting both the lens (WO bracket) and the camera (ZWO camera bracket), both of which have different centre heights w.r.t. the Vixen bar and hence needed shimming to get the axis as parallel to the bar as possible. What a game!

I think stepping down to f2.8 is a good move. I use a 49mm step-down-ring which I think gives cleaner star shapes and stops down to effectively f2.6.

Sorry I can't be of more help 😐

Adrian

 

[SAW]

I have some tilt adjuster shims but this seem to make it worse. I might just try a very thin shim/spacer next and maybe try f/4.

Edited February 26, 2023 by SAW

[Adreneline]

2 minutes ago, SAW said:

I have some tilt adjuster shims but this seem to make it worse. I might just try a very thin shim/spacer next and maybe try f/4.

My decided that my tilt was all coming from 'droop' in the imaging train, even though I had replaced the EoS fitting with an M42 screw end-plate on the lens.

I also found some of my thicker plastic shims were not consistently thick around their perimeter - cheap and cheerful and now all in an incinerator somewhere! We are talking fractions of a millimetre making all the difference. I decided I was never going to get zero tilt and it was less stressful to crop off the offending peripheral regions - a cop-out I know but life is too short and clear nights to rare. 😆

Good luck.

[SAW]

So would I need to add a tilt shim at the corner with the higher reading or at the opposite corner ?

[SAW]

Here is a single image just stretched then I've measured the tilt, as you can see it's a completley different reading compared to a stacked image ? Is it best to measure a single image or stacked one ?

[Adreneline]

32 minutes ago, SAW said:

So would I need to add a tilt shim at the corner with the higher reading or at the opposite corner ?

Good question - and I really don't know. Is your sensor orthogonal to the Vixen bar? I have mine in 'landscape' orientation - looking at your image I would hazard a guess your sensor is the same.

24 minutes ago, SAW said:

Is it best to measure a single image or stacked one ?

A single image is preferable as the stacking will reduce aberrations etc.

I know some folk use one of the tilt adjusters (CTU ?) you can buy. If you are using NINA then I understand there is a plug-in available to analyse sensor tilt/misalignment etc.

I used a digital level to eliminate the droop in my imaging train; the changes/adjustment I made all helped but I still have some tilt/misalignment despite my best (inadequate) efforts.

I suppose it could be down to sensor tilt but if that is the case I am going to live with it.

Adrian

[Adreneline]

Just now, Adreneline said:

If you are using NINA then I understand there is a plug-in available to analyse sensor tilt/misalignment etc.

P.S. There is a thread on the AstroBin forum where someone has used NINA to completely eliminate tilt - all explained in great detail.