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Imaging with the Samyang 135mm f2


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Hi Space Oddities, I'm using DSS, lightroom and Affinity photo. I will revisit this sometime because I know a bit more about colour balancing now. Thanks for the tips! 

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This lens is really something else.   Always seems to produce a reasonable image no matter what !!

Here are two for the 'Continuing Projects'  Folder.   Both LUM only.  Atik 414ex mono.  About an hour total integration on both.

M31: 7.5 sec exposures ( lots of them !!)

Shark Nebula:  3mins subs with lots of passing cloud and a 3/4 Moon. Taken Thursday night.

M31_LUM_only_5_and_7_sdec_subs-Luminance-session_25mins-St.thumb.jpg.a4f25af5ed6021835c0a26995b801d5c.jpg shark_samy135mm_2-Luminance-session2222_-NoSt.jpg.d91adc820c18c715a342fe11f7ac34a5.jpg

 

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I finally managed to get first light with Samyang 135mm connected to my ASI294MC Pro last night.

There was a bit of faffing about obtaining focus with the lens & the new 32mm guide scope (still not happy with the guide scope focus but it worked). So I went for the Sadr Region for comparison with an image I took back in August with my modded EOS 1300D and Sadr had already past the meridian when I started.

The ASI294MC was at -15°C, gain 120, offset 8 and fitted with L-eXtreme filter. Lens at f2.8 and I managed 1h 50m of 90s subs with the rig fixed to my HEQ5. Stacked in DSS with only darks (haven't take the flats or dark flats yet) and processed in PI.

I may have reduced the stars a little too much in this one, so I may have another go at it later, and there's a little bit of tilt noticeable in the stars on the left hand side if you're pixel-peeking. ;)

So here's the image from last night and the DSLR version below (which was 51 minutes at ISO400).

Sadr-19092021-1h50m-NB.png.cc03db40549a41124dd30b41ac1f9a1f.png

2066294178_SadrRegion-22072021-51m-ISO400x30s.png.e257bb6b2d2b50485ffac90d102bf66d.png

 

 

Edited by Budgie1
Forgot to mention the L-eXtreme.
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46 minutes ago, Budgie1 said:

I finally managed to get first light with Samyang 135mm connected to my ASI294MC Pro last night.

There was a bit of faffing about obtaining focus with the lens & the new 32mm guide scope (still not happy with the guide scope focus but it worked). So I went for the Sadr Region for comparison with an image I took back in August with my modded EOS 1300D and Sadr had already past the meridian when I started.

The ASI294MC was at -15°C, gain 120, offset 8 and fitted with L-eXtreme filter. Lens at f2.8 and I managed 1h 50m of 90s subs with the rig fixed to my HEQ5. Stacked in DSS with only darks (haven't take the flats or dark flats yet) and processed in PI.

I may have reduced the stars a little too much in this one, so I may have another go at it later, and there's a little bit of tilt noticeable in the stars on the left hand side if you're pixel-peeking. ;)

So here's the image from last night and the DSLR version below (which was 51 minutes at ISO400).

Sadr-19092021-1h50m-NB.png.cc03db40549a41124dd30b41ac1f9a1f.png

2066294178_SadrRegion-22072021-51m-ISO400x30s.png.e257bb6b2d2b50485ffac90d102bf66d.png

 

 

The difference is amazing really you can see artefacts from vignette where you have not taken flats but overall great shot! I am trying to see the tilt you mention but not able to get in close enough to see it... Annoying really as I posted an image a few weeks back where it was apparent and that was at f3.5. Not sure if I should try adding any spacers as it was only apparent on one side of the image could be trial and error or may just have to live with it. 

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1 hour ago, Simon Pepper said:

The difference is amazing really you can see artefacts from vignette where you have not taken flats but overall great shot! I am trying to see the tilt you mention but not able to get in close enough to see it... Annoying really as I posted an image a few weeks back where it was apparent and that was at f3.5. Not sure if I should try adding any spacers as it was only apparent on one side of the image could be trial and error or may just have to live with it. 

Looking at it, you can't see the tilt artefacts in the completed image due to the size reduction.

I did another process of the image and took these two close ups:

This is the left hand side of the image where you can see a blue hue on the top right of the stars. I think this is tilt because they all point in the same direction, no matter whether the stars are at the bottom or top of the left hand side. If it were back spacing then it would point towards or away from the centre (as I understand it).

1949950457_LeftSide.png.54dcb22a9a1c1d5895b2ccfb68049faa.png

This is the right hand side of the image with nice round stars:

1948584914_RightSide.png.e7f2484182723847f108b98ba88c2686.png

I'm using the ZWO Canon EF to T2 adaptor and there's a little movement in the connection between the adaptor and lens so I think that may be the cause. I did think about getting the Astro Essentials adaptor which replaces the Canon mounting on the lens, but I still want the option of using the EOS camera occasionally.

 

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13 minutes ago, Budgie1 said:

Looking at it, you can't see the tilt artefacts in the completed image due to the size reduction.

I did another process of the image and took these two close ups:

This is the left hand side of the image where you can see a blue hue on the top right of the stars. I think this is tilt because they all point in the same direction, no matter whether the stars are at the bottom or top of the left hand side. If it were back spacing then it would point towards or away from the centre (as I understand it).

1949950457_LeftSide.png.54dcb22a9a1c1d5895b2ccfb68049faa.png

This is the right hand side of the image with nice round stars:

1948584914_RightSide.png.e7f2484182723847f108b98ba88c2686.png

I'm using the ZWO Canon EF to T2 adaptor and there's a little movement in the connection between the adaptor and lens so I think that may be the cause. I did think about getting the Astro Essentials adaptor which replaces the Canon mounting on the lens, but I still want the option of using the EOS camera occasionally.

 

Have you seen this thread...

It should be useful in determining where the tilt originates and could be used on the whole camera plus adapters in the imaging train.

Alan

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49 minutes ago, Budgie1 said:

 

I'm using the ZWO Canon EF to T2 adaptor and there's a little movement in the connection between the adaptor and lens so I think that may be the cause. I did think about getting the Astro Essentials adaptor which replaces the Canon mounting on the lens, but I still want the option of using the EOS camera occasionally.

 

Potentially you could still use it with an ultra short adapter like this one: https://www.firstlightoptics.com/adapters/ts-ultra-short-adapter-from-m48-to-canon-eos-ef-only-1-mm-length.html

Your back focus distance would be increased by 1mm, so you might not be able to use the lens at infinity (but perhaps it's till possible, I think the lens can focus 'past' infinity). But if you use the lens for portraits or similar, that shouldn't be an issue.

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Thanks Alan & Pierre,

I've see the thread, Alan, but haven't read through it as I didn't tilt until this morning! :D

Pierre, I'm not sure that adaptor will help because the movement is on ZWO Canon adaptor side, not the lens. The lens is tights when connected to my DSLR and I don't see the same issue on images from that camera.

As I said above, once the images is processed and reduced to my normal PNG size of 1200x800 px then you can see the tilt effects, so I'm not really that worried about it. I included the info in case others have the same with that setup. ;)

Anyway, I had another go at processing it this afternoon and used the OSC Hubble Palette technique, which makes a difference and I think has brought out more nebulosity. Hope you like it. 

Sadr-19092021-1h50m-NB-Hubble.png.04ee1951a3121247033d84fc5e8f3a65.png

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I wasnt going to bother processing this one (NGC6888) as i've been struggling with focus, the stars aren't great & PA looks slightly out.  I decided to get more practise in with PI which i'm loving & its still a maybe passable image. I'm using the L-eXtreme filter at the moment & have seen a couple of tips on focus with this filter, upping gain etc so i'll have another crack this evening if the forecasted clear couple of hours emerges later. 

Ive still a very long way to go but loving the journey so far despite the many frustrations.

207x 180sec
30x Darks
30x Flats
200x Bias
Calibrated & Processed in PI
Bortle 4 SQ 21.66
Using equipment as per my signature

Thanks for looking

Steve

Screenshot (81).png

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 I wasnt happy at all with the image I posted above last night & after a bit of research & coming across a great tutorial by Cuiv, The Lazy Geek on YouTube using NormalizeScaleGradient in PI to choose a best reference frame I had another crack at it working into the very early hours of this morning 😒.

I ended up loosing over 7hrs of data but realised that it was garbage so was never going to be any good in the stack. I also used deconvolution to make the stars slightly better, this has resulted in some ringing if you go pixel peeping even though I adjusted parameters for it. I'm much, much happier with this & kept it in its normal colours rather than the Hubble Palette.
As usual a JPEG doesn't do it justice.

Steve

Image26.jpg

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These images are increadible 😁 i tried Andromeda a few nights ago and got nothing useful, so glad other folks are getting useful data, it's definitely keeping my spirits up 😁 keep up the good work 😁

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7 minutes ago, RobST said:

These images are increadible 😁 i tried Andromeda a few nights ago and got nothing useful, so glad other folks are getting useful data, it's definitely keeping my spirits up 😁 keep up the good work 😁

@RobST  Stick at it mate, you'll get there in the end. I spend 95% of my AP time banging my head against the garden wall 🤣

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Looks awesome Steve, really nice colour choice in the second image.

I've recently bought the full PI and loving it so far although I'm taking it slowly and really trying to learn each process/script before moving on (expect to see a completed image sometime at the end of 2025😂).

Right now I've got as far as Pixelmath and coming from a long time Photoshop user PI is getting weird but I'II keep pressing on.

Hope you are well mate.👍

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9 minutes ago, Mike73 said:

Looks awesome Steve, really nice colour choice in the second image.

I've recently bought the full PI and loving it so far although I'm taking it slowly and really trying to learn each process/script before moving on (expect to see a completed image sometime at the end of 2025😂).

Right now I've got as far as Pixelmath and coming from a long time Photoshop user PI is getting weird but I'II keep pressing on.

Hope you are well mate.👍

@Mike73 Hi Mike, I'm good cheers. I've had this data for around a month & only just got round to processing it due to work which is thankfully slowing a little now. PI is great, I recently bought the full license & i'm really liking it but theres so much to learn its easy to get lost. I'm using several bits from several workflows & just slowly putting together a workflow  of my own. And yes, PixelMath is a whole world of 'What on earth.......' 🤣

 

Edited by nephilim
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1 hour ago, nephilim said:

@RobST  Stick at it mate, you'll get there in the end. I spend 95% of my AP time banging my head against the garden wall 🤣

Cheers Pal, it was the first time i had set up my az eq6 pro so it took longer than expected lol, my tracking was good though, but the high altitude clouds screwed me over, hopefully some clear nights coming 😀

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On 09/09/2021 at 15:37, Space Oddities said:

Honestly I think all Samyang 135's have one ugly corner somehow... But I think most bayonet adapters don't help. At least that was the case with my copy. When I replaced the Canon mount of my lens by a M48 mount (with this excellent adapter), I believe that my bad corner improved. It's also a much easier adaptation to astro cameras!

Hi Pierre

 

Can you still use a filter with this config? 

Thanks

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Hi Powerlord I am using a ZWO OSC with a 2" mounted l extreme so I need the option of a filter holder or drawer. My issue is this tilt that I am facing I am having to throw nights away or use starless versions as its hurting me :( I am wondering if I need to account for the filter and by adding 2mm spacer it may fix it. Although not sure how I do that or what spacer I need? Thanks

 

Edit I do actually have a ZWO filter drawer as well so perhaps this adapter will work  just need to do some measurements. 

 

https://www.firstlightoptics.com/adapters/astro-essentials-samyang-lens-to-m48-adapter.html

 

Edited by Simon Pepper
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yeh I've thought of getting one of those.

At present I've shot with my asi533 and the zwo canon adapter. you can screw the 2" into that - it's a pity tricky, but it does screw into the inside of the adapter.

that worked fine for me.

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On 27/09/2021 at 11:08, Simon Pepper said:

Hi Pierre

 

Can you still use a filter with this config? 

Thanks

Hi Simon,

I'm using the Baader UFC filter slider. It's 16mm thick, with M48 female and T2 male connections. I then use spacers to get to 44mm (I'm using the M48 adapter instead of the Canon mount).

I believe any other filter slider would work just fine. Just make sure the total thickness, from the back of the lens to the sensor, is 44mm. You might need to fine tune this with thin spacers (0.1, 0.2 or 0.5mm) depending on your imaging train.

Hope that helps :) 

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From the 29th September. NGC7000.

The forecast was for clear weather but, of course, the clouds rolled in with the result that I only got 8 120sec exposures with my ASI533 and the Samyang on my AVX unguided.

I did have one issue that someone may be able to help with - I tried to platesolve in APT but it said failed but with no error messages. I have the profile down as 135 focal length and scope diameter as 82mm. Does anyone have any suggestions of what it should be so that pointcraft works? Processed in APP with a few tweeks in Affinity.

 

Anyway for a total of 16mins exposure I can't complain.

 

 

NGC7000-RGB-session_1-St.png

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