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Uranium235

Imaging with the Samyang 135mm f2

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On 25/07/2020 at 17:09, geordie85 said:

That shouldn't be a problem as long as you can eliminate all of the tilt.

This is a 2 pane mosaic I did. I still have slight tilt on the left which I need to eliminate

1789196767_2paneorionredo2.jpg.db3506888086258d2c8bfcd370909115.jpg

I'm using the Samyang to t2 adapter from flo and all the connections are screwed (qhy183-qhycfw3s-qhyoags).

The adapter could be better manufactured though...

The problem is that usually i get different aberrations in the corners (for example in one corner the stars are seagull shaped, in another triangles, in the third coma etc).

I don't know if this is a tilt related problem...

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After somewhat of a hiatus - I appear to be imminently back in the game (soon as dark come back anyway!), I chanced upon a 428EX mono for an unbelievable price so I snapped it up.

So I'm considering a 135mm F2 for the FOV, speed and price for predominately narrowband imaging when paired with the 428, the concern is the under sampling - I would assume for best results I'd ideally want a scope in the 400-600mm range?  The issue with the longer focal range is the size of the Ha targets!

Anyone have any thoughts on the subject?

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Posted (edited)
1 hour ago, John78 said:

when paired with the 428, the concern is the under sampling

I used a 428ex-mono with my Samyang 135 and found the undersampling to be an issue in the end as the star shapes were not good at all.  Having said that I quite like starless images when imaging nebula because I feel it can make the structure of the nebula more apparent so I was quite happy to remove the stars and just process an image of the nebula as at the end of the day I am imaging the nebula and not the stars. I tend not to post starless images because I sense most don't like the lack of stars as it is apparently not a true representation of the nebula - not sure I follow the logic of that one really as most of the stars are no where near the nebula in question!

Prior to using the 135mm I used my 428 with an ED80. As you point out the fov is quite restricted for the larger nebula targets so unless you are into mosaics in a big way it can be frustrating.

There's no easy answer - or maybe there is and I just don't know it. :)

 

Edited by Adreneline

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I managed to add some data to my previous Veil nebula image and I really feel like it made a huge improvement to the detail and amount of nebulosity. The final image is still only 39min, because of some cloud dodging, consisting of 90sec exposures, ISO800 and F/2.8 with my Nikon D3300. I also managed to add 10 darks.

1913380296_Veilcomplex.thumb.jpg.dde848cfb883e6e6c1a55b0b0c7e26be.jpg

I think I need to start using photoshop to process the stars since I always feel like they are either overexposed or extremely ugly looking.

Victor

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I keep asking myself, why it is not good to use those lenses at wide open F/2? i have Canon 135mm, so why can't i use it wide open with nice results? I read it is about light shift at that speed of F2, but isn't there filters for that? I mean there is Baader F2 Highspeed filters for F2 used with RASA and Hyperstar, so can't those filters be used with F2 or faster lenses? or does boarder NB filters be any good here?

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On 28/07/2020 at 17:21, Victor Boesen said:

I managed to add some data to my previous Veil nebula image and I really feel like it made a huge improvement to the detail and amount of nebulosity. The final image is still only 39min, because of some cloud dodging, consisting of 90sec exposures, ISO800 and F/2.8 with my Nikon D3300. I also managed to add 10 darks.

I think I need to start using photoshop to process the stars since I always feel like they are either overexposed or extremely ugly looking.

Victor

ISO800 / 90Sec!!!
Jealous!!!! :)

My ISO100/30sec usually are almost overexposed! (Light Pollution issue....)

Nice pic!

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2 hours ago, RolandKol said:

ISO800 / 90Sec!!!
Jealous!!!! :)

My ISO100/30sec usually are almost overexposed! (Light Pollution issue....)

Nice pic!

I can definitely relate!! I live under Bortle 7/8 skies which is horrible but I was at my grandparent's Bortle 4 skies when I captured the images;)

Thanks a lot!

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Hi All

Can you take a look at the corners of this picture, do you think the star shapes are a spacing issue

1872633702_HAStackSadr.thumb.png.8528d852ba82708094ed03c5d0cc4042.png

This is the HaRGB version, cropped but still needs some flats applying

40 x 180sec HA

60 x 60sec R&B

30 x 60sec G

All shot at F2.8

221306804_Sadrtk1.thumb.png.4ce9ab144a3fd44caac15acafcb1587a.png

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Hello, first post in this thread.

I've been following this thread for a while now and eventually built my own system around this lens, of which much information from here was super useful, so kind thanks to the community here for that. I've managed to complete a couple of projects over the past four months with it, and I'm supper happy with it's performance, ease of use and lightness. I have a Windows PC stick attached to the tripod so I can remote desktop into it and the whole rig is just a joy and a breeze to use! 

Thanks again everyone and hope you like the images. Any questions or comments welcome :)

Best,

Minos 

P.S. Full details in the AB links.

IMG_2133.thumb.JPEG.b0fa3525f707bfbc2477d882fa99e399.JPEG

https://www.astrobin.com/04ok4m/0/

IC1396_Final.thumb.png.6a55ddd77e8847f0ec6a342a73b99d5e.png

https://www.astrobin.com/i0frda/?nc=user

RpnP9eI1Dc7w_16536x16536_kWXURFLk.thumb.png.1a831713979681b922b1366cf2b47e57.png

 

 

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Like some others here, I was so inspired by this thread ealier this year I decided to try the Samyang 135/f2 myself.

Delayed by covid deliveries, the lack of clear / dark skies etc and my own laziness, at last I've just achieved first light and mainly wanted to post to just say thanks to those that helped. 

At the moment I'm just experimenting using the lens matched with a modded Canon 550D and Philippe's excellent AstroKraken 3D printed bracket and microfocuser.  I had planned  to spend more time on Cygnus but the aforementioned skies didn't co-operate.  Notwithstanding,  I'm pleased with the intial short images of the Veil, Cygnus and especially NAN, unfortunately all <=1 hours integration of 120sec subs.  Still it's more than whetted my appetite and I hope over the coming months to change to a mono camera + refine the overall set-up.  I just love the FOV and quality obtained with this lens + the relative ease setting up = a real winner with UK condtions. 

 

 

NAN Stack2CGxF5cropA (Medium).png

Cygnus LRGBC2 PNG-denoise-denoise (Medium).png

 

Veil_Stretch_DBE+1-denoise80%Crop (Medium).png

IMG_20200905_184816707 (Medium).jpg

Edited by groberts
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Superb! 👏

Minos, out of curiosity, how did you manage to attach the OAG with such a short flange distance?

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Hi all,

Just an observation I've come across during processing after using the samyang- I've noticed my stars have different sizes in the different colour channels. Red seems to be more bloated than the blue channel, with the green channel showing the tightest, smallest stars. I think this may be contributing to some slight halos (namely red and purple) around some stars. Nothing major, but noticeable if you zoom right in. I'm imaging with a DSLR, using a bahtinov mask for focusing, any recommendations on how I could prevent the bloat? Or is it a case of the limits of the optics? Or maybe I could be improving my focusing further?

Mark

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2 hours ago, Mark1489 said:

any recommendations on how I could prevent the bloat?

Despite perceived wisdom (adding more glass, reflections, etc.) I use a Hoya UV/IR cut filter and it solved all my issues - especially with OIII, Green and Blue. I didn't notice any Red (or Ha or SII) bloating with my lens. The filter also had the effect of making the FWHM variations between filters much less.

Adrian

Edited by Adreneline
Clarification
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Hi, does anyone use the ZWO tilt adapter to compensate the tilt of Samyang 135?  

Using the image inspector in ASTAP, the tilt (FHD) of my Samyang 135 in Sony A7III and ASI533 pro are 1.1 & 0.8 respectively.  I just wondering if the tilt is caused by the different focus points on the lens/sensor, is it possible to adjust it by the tilt adapter?

My local seller said they can send the lens to Korea for repair, but it takes 3 months and I doubt Samyang cannot fix it. Actually I do find the unrounded stars in the image, however, I cannot find noticeable differences in the four corners at infinity during the daytime (wide opened). If the tilt adapter cannot help, I may just sell the lens to people who do not take astrophotography...  

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Hi! Would anyone happen to know if I could use the space/redcat collar with the samyang 135mm lens. It has an inner diameter of 69mm and I've read that some people use 70mm rings so it should fit?

https://www.firstlightoptics.com/tube-rings/william-optics-redcat-spacecat-single-mounting-ring-black.html

Victor

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16 hours ago, Victor Boesen said:

Hi! Would anyone happen to know if I could use the space/redcat collar with the samyang 135mm lens. It has an inner diameter of 69mm and I've read that some people use 70mm rings so it should fit?

https://www.firstlightoptics.com/tube-rings/william-optics-redcat-spacecat-single-mounting-ring-black.html

Victor

Hi Victor, the answer is yes, that's how I use it. HTH :)

Minos

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4 hours ago, mAnKiNd said:

Hi Victor, the answer is yes, that's how I use it. HTH :)

Minos

Thanks, just what I needed!! Great to be sure before purchasing;)

Victor

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16 hours ago, Victor Boesen said:

Thanks, just what I needed!! Great to be sure before purchasing;)

Victor

Cool

the only two things to consider, is that you need to preset you aperture (I have mine at f4 for example) before you clamp on the ring. Also, the locking screw wont close the ring fully down, but has nevertheless been rock solid since the day I installed it without loosening up. 

HTH

Minos

21C84801-D35F-4E7F-9D05-45D33C28D470.jpeg

BEA40E08-758A-4E28-8D92-4804C4F55761.jpeg

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23 hours ago, mAnKiNd said:

Cool

the only two things to consider, is that you need to preset you aperture (I have mine at f4 for example) before you clamp on the ring. Also, the locking screw wont close the ring fully down, but has nevertheless been rock solid since the day I installed it without loosening up. 

HTH

Minos

21C84801-D35F-4E7F-9D05-45D33C28D470.jpeg

BEA40E08-758A-4E28-8D92-4804C4F55761.jpeg

Hi mAnKiNd

Where did you get the bracket for the Stepper motor?

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4 hours ago, KyleStoke said:

Hi mAnKiNd

Where did you get the bracket for the Stepper motor?

you mean the bracket that comes with the Pegasus Focuscube?

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18 minutes ago, mAnKiNd said:

you mean the bracket that comes with the Pegasus Focuscube?

Yeah thats the one cheers

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