Imaging with the Samyang 135mm f2

[geordie85]

45 minutes ago, Uranium235 said:

Still waiting for the lens... ughh this is like pulling teeth...lol 

I severally regret selling mine. So mucih so that I'm on the look out for another one. 

[Space Oddities]

21 minutes ago, geordie85 said:

I severally regret selling mine. So mucih so that I'm on the look out for another one. 

There's a good deal running on Amazon France on the Canon version: 390€ or about 350£ (+ shipping, probably less than 10€)

https://www.amazon.fr/Samyang-135-2-0-UMC-Objectifs/dp/B00TS9GLSE/ref=sr_1_1

I don't think you can find a cheaper one!

Edited August 22, 2019 by Space Oddities

[Uranium235]

9 hours ago, Space Oddities said:

Rob, I'm curious about the impact of your modification on the flange distance of the lens? Is it going to be similar to the Canon bayonet?

I'm trying to keep it as close to the original distance of 44mm. But I can afford it to be up to 2-3 mm thicker (still leaves loads of room for a FW).

I'm making the m48 thread just 4 or 5 mm.  That way any extension ring or FW will screw right up against the lens mod if you so wish ☺ 

 

[Adam J]

17 minutes ago, Uranium235 said:

I'm trying to keep it as close to the original distance of 44mm. But I can afford it to be up to 2-3 mm thicker (still leaves loads of room for a FW).

I'm making the m48 thread just 4 or 5 mm.  That way any extension ring or FW will screw right up against the lens mod if you so wish ☺ 

 

whats your thoughts on reducing that to t2 thread straight after the M48 thread? would that result in vignetting?

[Uranium235]

6 hours ago, Adam J said:

whats your thoughts on reducing that to t2 thread straight after the M48 thread? would that result in vignetting?

If the FW is attached directly to the camera - the m48-T2 adaptor will be about 11mm. 

If you have a large format camera (diagonal of 22mm +l, I would use 36mm or 2 inch filters anyway. 

The shorter I make the mod, the more options the user has got to configure it in a way that suits their camera. ☺

[Allinthehead]

On 21/08/2019 at 17:41, Adam J said:

Hi what size filters are you using with the lens and at what F-ratio with the ASI1600mm pro?

Hi. 1.25 filters and all shot at f2

[Adam J]

2 hours ago, Allinthehead said:

Hi. 1.25 filters and all shot at f2

I assume then that there was some vignetting but that it was still correctable. 

[Allinthehead]

3 minutes ago, Adam J said:

I assume then that there was some vignetting but that it was still correctable. 

Yes a little vignetting but not an issue with flats. Just get the filters as close to the camera as possible. 

[Adreneline]

7 minutes ago, Adam J said:

some vignetting

This is my Ha master flat using 135mm + ZWO-EoS adapter + ZWO-EFW + ASI1600

It's the same for OIII and SII.

I'm surprised it's not symmetrical but I've not noticed any issues on the finished images.

Maybe I need to recalibrate the ZWO-EFW.

Adrian

[Adam J]

Just now, Adreneline said:

This is my Ha master flat using 135mm + ZWO-EoS adapter + ZWO-EFW + ASI1600

It's the same for OIII and SII.

I'm surprised it's not symmetrical but I've not noticed any issues on the finished images.

Maybe I need to recalibrate the ZWO-EFW.

Adrian

Might be an idea was this at F2?

[Adreneline]

4 minutes ago, Adam J said:

was this at F2

Yes.

I was using 2" filters with a fully manual TS filter holder but decided to start using my 1.25" filters.

Not done any imaging for a month cos' I'm awaiting a new mount - having sold the old one!

We've had a lot of clear nights over the last month but I'm sure the two are in no way related.

[Mark1489]

First go at Andromeda! 

Nikon D5300, ISO 1600, 53 x 60 secs @f2.8 

 

 

[michaelmorris]

Lovely shot.

[Adreneline]

1 hour ago, Mark1489 said:

First go at Andromeda!

Very nice! - I like it a lot. What mount are you using? Was it guided?

[Mark1489]

43 minutes ago, Adreneline said:

Very nice! - I like it a lot. What mount are you using? Was it guided?

Thank you! 😀 I’m using a Star Adventurer, Unguided. Still need to pin down the focus better, may have to invest in a micro focuser! 

[Adreneline]

25 minutes ago, Mark1489 said:

Still need to pin down the focus better

I think you've done a pretty fine job of focussing on this image.

I use Live view on my 70D and/or A7. I've tried a mechanical fine focusser (3D printed type) which was ok'ish albeit a bit big. You can get metal versions which are more compact - and more expensive. I've also used a SkyWatcher focusser with toothed belt; better because you can sit inside and get very fine control along with BackyardEoS (for the Canon) providing a measure of FWHM. (I love BYEoS and I presume BYNikon is every bit as good). It's a shame there is no BYSony!

Well done! You should be well pleased with the end result. The Samyang 135mm is brilliant for wider field imaging.

Adrian

 

[Mark1489]

25 minutes ago, Adreneline said:

I think you've done a pretty fine job of focussing on this image.

I use Live view on my 70D and/or A7. I've tried a mechanical fine focusser (3D printed type) which was ok'ish albeit a bit big. You can get metal versions which are more compact - and more expensive. I've also used a SkyWatcher focusser with toothed belt; better because you can sit inside and get very fine control along with BackyardEoS (for the Canon) providing a measure of FWHM. (I love BYEoS and I presume BYNikon is every bit as good). It's a shame there is no BYSony!

Well done! You should be well pleased with the end result. The Samyang 135mm is brilliant for wider field imaging.

Adrian

 

Cheers, I’ve been using a 3D printed bahtinov mask for the Samyang that I bought online which does help things, though I tend to get elongation of stars in one corner if the focus is slightly out, suppose it’s what you get with fast optics!  I’ve been trying to experiment focusing in different areas instead of the image centre but I think I need to be able to fine tune! A manual micro focuser would do me fine, I like to keep things simple haha! You’re right, BY Eos/Nikon is great! 

Very kind of you to say, thank you! I am very pleased! Looking forward to seeing more of your images, they’re inspiring me! 

Mark 

 

 

 

[Adreneline]

7 minutes ago, Mark1489 said:

A manual micro focuser would do me fine

Hi Mark,

This is the mechanical version I tried - I bought it from here. It worked fine but was tricky to set up initially. I bought one for my 85mm Samyang as well but both are now totally surplus to requirements as I've gone SW focusser route instead.

 

12 minutes ago, Mark1489 said:

elongation of stars in one corner

My images also suffer in this respect but more so when I use the lens with an ASI1600. I'm hoping I've largely solved the "droop problem" by switching to a ZWO EoS adapter. As you say, using the lens at F2 has advantages and disadvantages.

Adrian

[Uranium235]

Behold... it's a miracle!! Three weeks this took (plus a load of chasing emails) 

But it's now "game on" 

[Alien 13]

12 minutes ago, Uranium235 said:

Behold... it's a miracle!! Three weeks this took (plus a load of chasing emails) 

But it's now "game on" 

I am sure you had 1...................................2.....................................or maybe 3 before, I would never let mine go 

Alan

[Ruud]

Awesome images, people. Thanks!

[Vixen4eva]

Took these over the last couple of weeks. All unguided on my EQ3 pro. 120 sec subs with my L pro filter and modded canon 450d.

Thanks for looking 

Alan

[Adreneline]

Took this one of the Heart and Soul last night unguided on my new iOptron CEM25-EC.

The image is 10x 120s + 180s + 300s multi-session combined in APP and post-processed in PI. I chose to use all the subs, even the one with the aircraft trail. There is minimal cropping to remove edge effects.

I think the star shapes are pretty good for unguided. I think the odd shape stars in the corners are down to the lens but I'd be interested to hear what others think.

Took thos one of NGC1499 after I'd finished the Ha of the Heart and Soul. This is also unguided, all 300s - 12 x Ha and OIII.

The combination of CEM25 and 135mm+ASI1600 could make a great grab-n-go setup.

Thanks for looking.

Adrian

Edited September 12, 2019 by Adreneline
Clarification

[Uranium235]

Update on the lens mod:

Should be a week, maybe two at tops. Once its back I'll have a better understanding of how much spacing Ive got to fill. I want it to be as close to the infinity stop as possible (in order to get the best corrected field).

[Uranium235]

On 12/09/2019 at 17:14, Adreneline said:

Took this one of the Heart and Soul last night unguided on my new iOptron CEM25-EC.

The image is 10x 120s + 180s + 300s multi-session combined in APP and post-processed in PI. I chose to use all the subs, even the one with the aircraft trail. There is minimal cropping to remove edge effects.

I think the star shapes are pretty good for unguided. I think the odd shape stars in the corners are down to the lens but I'd be interested to hear what others think.

Took thos one of NGC1499 after I'd finished the Ha of the Heart and Soul. This is also unguided, all 300s - 12 x Ha and OIII.

The combination of CEM25 and 135mm+ASI1600 could make a great grab-n-go setup.

 

Thanks for looking.

Adrian

The right hand side of your images displays out of focus stars. This also corresponds with the master flat you posted earlier.

Whether that is due to droop in your imaging train, I dont know. But an idea would be to test the lens on a DSLR and take some flats with that - if you get the same vignetting pattern, it will be the lens. If not, then you need to look at the way its attached to your astro camera as to what is causing it.