Imaging with the Samyang 135mm f2

[geordie85]

19 minutes ago, Craney said:

I am so glad you said that.   I've been trying to wrestle the Squid out of the clutches of darkness for the last 2 weeks.

Even resorting to 10min subs for Oiii ...... unheard of !!!   

I may try a few more (short) nights and do a massive collective stack in APP.

This is the best I got in Oxygen..

This is 3 hours of 600s subs.  (Atik 414ex   which is an amazingly sensitive camera).

 

Its definitely there, you just need more data. 

Is that a pure O111 image? What are you using for stacking? 

I only ask because you've got coloured noise in what should be a mono image. 

[Craney]

6 minutes ago, geordie85 said:

Is that a pure O111 image? What are you using for stacking? 

I only ask because you've got coloured noise in what should be a mono image. 

Wow..!!  that's a great spot.      <Super-powers>

Yes, it is Oiii and I used APP.

I noticed that my acquisition software (APT) had identified the Atik (mono) as my other camera, the QHY8 (OSC)... and gave some technicolor weirdness when I was trying to use a focusing mask.

It still behaved normally though in terms of cooling and operation.

Because I was off into the hills to photograph the comet  I  didn't  have time to try to solve it and just let it run.   The initial Halpha subs 'looked' mono and  decent so I didn't think much more of it.

Sounds like the drivers  may have got their knickers in a twist.

I wonder if it has had its performance 'clipped' as a consequence ??.....  Maybe there is some hope yet to get the Squid.

 

[silentrunning]

Well it's built, appears to work and is now in situ! It maintains the Canon bayonet on the lens. Outside of the canon connector is an external thread of 58mm diameter 1mm pitch that threads into an equivalent female thread built into the custom FW adapter. This eats into the space available for the screws that connect the flange to the FW so I had to print my own tiny screws with 2mm heads!!! I can now achieve minute, <0.05mm adjustments to the lens to chip distance and hopefully get close to the ideal 44mm. Next clear night I'll have a play and see what effects this distance has on the various out field aberrations.

[Uranium235]

On 13/07/2020 at 19:31, Adreneline said:

I'm coming to the conclusion that the Samyang 135mm + ASI1600 might not be the best combination to capture the Squid nebula within the Bat Nebula (Sh2-129). This is 60 mins of Ha and SII and 180 mins of OIII (all 180s subs).

I'll go for more OIII but I'm not confident I have the resolving power! There again my processing skills may be the limiting factor.

Thanks for looking.

Adrian

 

Going for the squid with ANY telescope/lens/camera is a recipie for insantiy... youve done well to get some of it. Ive known people spending 40+ hours, just to get that little bit.

[Craney]

29 minutes ago, Uranium235 said:

Going for the squid with ANY telescope/lens/camera is a recipie for insantiy... 

For some it is the White Whale, for us it is the Blue Squid.....

[Adreneline]

1 hour ago, Uranium235 said:

Going for the squid with ANY telescope/lens/camera is a recipie for insantiy...

It's like trying to grasp the Holy Grail - it might be as well to give up while I can!

1 hour ago, Uranium235 said:

youve done well to get some of it.

Thank you - I've tried binning the OIII data but there was no discernible improvement.

1 hour ago, Craney said:

For some it is the White Whale

“The White Whale swam before him as the monomaniac incarnation of all those malicious agencies which some deep men feel eating them, till they are left living with half a heart and half a lung.”

Definitely better stop! Mind you I should have stopped punishing myself when I read Moby Dick as well. Once I got to the end I'm not sure I was the better for it. 🤔

Adrian

 

 

Edited July 15, 2020 by Adreneline
Typo

[Craney]

27 minutes ago, Adreneline said:

the monomaniac ...

Ha!! ...40+ hours on Oiii....

 

[silentrunning]

Well the adjustable adapter allowed me to get the QHY11 near to if not bang on the focal plane of the lens. The field on this image is so much flatter than with the previous adapter.

 

 

 

[Adreneline]

59 minutes ago, silentrunning said:

The field on this image is so much flatter than with the previous adapter.

Glad you've got it nailed. Is this image cropped at all? The aspect ratio looks almost like 16:9.

What was the final spacing between the sensor and the lens end plate? Was it bang on 44mm?

Adrian

Edited July 19, 2020 by Adreneline
Typo

[Victor Boesen]

I finally purchased this lens a couple days ago after wanting it for a coupe of years now!! I got to test it out on NEOWISE the first evening and I am so impressed with how sharp it is with my Nikon D3300. I know it's a crop sensor DSLR but it easily handled F/2.8 without any problem. The following image is officially my first contribution to this topic after a couple years of lurking around

The image isn't anything special since it's not completely dark here in Denmark so I'm fighting with a lot of gradients from daylight towards the north. The image consists of 8X45sec exposures at F/2.8 and ISO 200 with a Nikon D3300 and the Samyang 135mm mounted on my star adventurer

I look forward to explore the possibilities of this lens which will fill in a nice gap between my Evostar 72 @420mm and 50mm prime F/1.8 lens!

Victor

[Adreneline]

8 minutes ago, Victor Boesen said:

I finally purchased this lens a couple days ago

Welcome to the Samyang 135 clan. Great first image!

Adrian

[silentrunning]

4 hours ago, Adreneline said:

Glad you've got it nailed. Is this image cropped at all? The aspect ratio looks almost like 16:9.

What was the final spacing between the sensor and the lens end plate? Was it bang on 44mm?

Adrian

Hi Adrian

Yes this imaged was cropped as I did a meridian flip half way through and didn't bother centering on the previous images. The full field of the frames obtained before the flip is shown below. I just adjusted the distance until I got the flattest frame so I assume I'm at the quoted 44mm for this lens.

and the corners via the AberrationInspector script in Pixinsight....

 

I'm not used to WF imaging and was surprised at the under sampling of the stars, something I don't have to worry about with my usual setup using a 12" GSO RC. I registered using drizzle and got a massive improvement..

 

 

 

Edited July 19, 2020 by silentrunning

[PeterCPC]

Comet Neowise - using a Canon 750d and the Samyang at f2.8.

Peter

[Craney]

This old favourite is on the rise in the early hours.   I could not resist a go with the 135mm on the Atik 414ex. (LRGB)

40mins L, then 10mins RGB :  All in  1 min subs.

This lens is a star-generator !!!

[tooth_dr]

3 hours ago, Craney said:

This old favourite is on the rise in the early hours.   I could not resist a go with the 135mm on the Atik 414ex. (LRGB)

40mins L, then 10mins RGB :  All in  1 min subs.

This lens is a star-generator !!!

Very nice Sean. You have a filter wheel between the lens and camera?

[Craney]

Thanks Adam,

Yes an ATIK EFW2.

 

[Victor Boesen]

I've quickly fallen in love with this lens!! After just two clear nights at a bortle 4 location I'm amazed with the capabilities of this lens:)

Victor

[Adreneline]

37 minutes ago, Victor Boesen said:

I've quickly fallen in love with this lens!!

I've found it to be so satisfying to use compared with my previous scopes (both now sold). I know you don't get a high level of detail but you get a great fov that is so well suited to the larger nebula targets. I've spent two nights on the Veil - on the left one hour on each filter, on the right two hours on each filter. Should I go for three hours on the next clear moonless night - whenever that might be!

Adrian

[Victor Boesen]

The colors and details in the faint whisps are noticeably sharper and more readily visible to my eye in the 2 hour image;)

[StamosP]

Hello all!

Has anyone tried combining the lens with an 183 camera?

I've tried 5 samples so far and i haven't found one performing as i would like. I know that this specific chip is very demanding due to the very small pixels (even though the chip's size is small) and it would be very helpful to know if i'm expecting too much...

[david_taurus83]

Does anyone use this wide open with a full frame sensor? I opted for the Canon 135 EF as it has autofocus and control both focus and aperture in APT. Not very good for astro wide open though! Below is an example of the Canon 135 on my 6D at f2, f3.5, f4 and f5.6.

[geordie85]

1 hour ago, StamosP said:

Hello all!

Has anyone tried combining the lens with an 183 camera?

I've tried 5 samples so far and i haven't found one performing as i would like. I know that this specific chip is very demanding due to the very small pixels (even though the chip's size is small) and it would be very helpful to know if i'm expecting too much...

What are you expecting? I've use this lens with a qhy183c

[StamosP]

2 hours ago, geordie85 said:

What are you expecting? I've use this lens with a qhy183c

Round stars everywhere in the field...

[geordie85]

17 minutes ago, StamosP said:

Round stars everywhere in the field...

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

[carastro]

Well I finally managed to sort out my focus problems, it was a daft human error in not screwing the EFW on properly due to doing it a cack handed way, and thank goodness I am imaging with the Samyang again.

I have ordered some extra parts for my Astrokraken mounting rings so I can have a ring round the CCD camera which hopefully will also help with the weight and give me more peace of mind that the EFW and CCD won't fall off again. (Luckily nothing got broken which is a miracle, thank goodness for rubber interlocking observatory matting). 

I have finally finished my 4 pane Cygnus mosaic and done a 5 in 1 image of the Lobster's claw, Bubble and Cave Nebula etc.

Quote

 

Edited July 25, 2020 by carastro