Space Oddities

Superb capture! Any plan to add some color?

The Samyang is a keeper! I think it's worth the extra cost versus cheaper/older lenses. Being able to shoot wide open and still get a decent result is a great advantage.

I've had zero time for astro in the last year, due to moving back to France, starting a new job, moving between different temporary homes, etc. But I couldn't resist to bring the Samyang with me, "just in case". My current temporary home happens to be in a suburban area with a fair amount of stars visible. Probably a Bortle 4.

The other day, I didn't have much motivation for a long AP session, plus it was first light for my new RST-135, so you never know what can go wrong. So I thought, why not keep it simple and try some EAA. Turns out, it was really nice! The RST-135 performed flawlessly, and the Samyang also worked well, even though I noticed some back spacing issue I need to solve. I used the ZWO ASI178MM-Cool and Baader filters. Didn't have a luminance filter in the wheel, only room for Ha, OIII and RGB. But that didn't stop me from enjoying the night sky from the comfort of my car, a good TV show on my iPad and an occasional look on what the ASIAIR is capturing.

Here are some of my observations that night, all are single exposures at f/2, mainly with the Ha filter and one of the RGB filters   No processing, just the autostretch from the ASIAIR.

Great news! 2 new filters are coming  

Antlia will release their own dual band filter, with 5nm bandpass on OIII and Ha. Cuiv has made a nice video to test his own copy. It seems to handle halos pretty well, but time will tell! Pricing should be above the L-Extreme, at $380, according to this CN thread (+ more test shots).

And Optolong just teased their new filter, the L-Ultimate, with a 3nm bandpass! I haven't found any more info about it, but Shawn from VisibleDark Youtube channel has an early copy and will release a test video soon. He says he'll compare the results to the Antlia filter. No info on the pricing, but given the specs, it probably won't be cheap.  

It's great to have so many options!  I'll update the table above accordingly when I have the chance.

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  

Here are a few pictures they shared over the past 2 years, including some test exposures (sadly, compressed by Facebook). Seems like a more final design! I like that they added a way to rotate the focuser with a timing belt, without the need to 3D print something  

https://www.facebook.com/williamoptics/posts/10162268748890383

https://www.facebook.com/williamoptics/posts/10162313785245383

https://www.facebook.com/williamoptics/posts/10164382273115383

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.

Lovely details, well done! It does look a bit green on my screen though, but that should be easy to correct by realigning the channels slightly. 

Are you using Photoshop? There's also a very nice free plugin called Hasta la Vista Green, for Windows only, but it usually does a great job to remove that green tint.

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!

What kind of adapter are you using? Canon/Nikon to T2? Do you have a picture of your setup maybe?

I haven't seen any test yet, but I don't think it will be optically as good as the RedCat. Which is okay, considering it's also cheaper.

It's only a guess of course, based on my experience with the FMA180: despite the "APO" in its name, it's not a true apochromatic telescope (probably due to the use of cheaper glass), and as a result, some stars show a blue fringing. That's a drawback that is easily corrected either in post or using a filter (Astronomik L3, Baader fringe killer, Baader Semi APO, etc.), and that is also counterbalanced with the low price, IMO.

I suspect the FMA230 to be the same kind of scope, with the same drawback ultimately. When a manufacturer uses high quality glass, it's generally printed in bold and underlined in the specs   Which would makes the RedCat optically superior (but more expensive)!

If you're looking at the best image quality, an alternative could be the Askar ACL 200mm. It's not too far off in terms of focal length & aperture, compared to the FMA230, but optically, from what I've seen at least, it's way better than the FMA180. Probably just as good as a RedCat in fact. But beware of the weight, it's 1.8kg!

So I would say, it all boils down to what is more important to you, between weight, image quality and price. Between the FMA180, FMA230, ACL200 and the RedCat, you have 4 solid options that can suit your needs  

Glad you found your focus!  

13 hours ago, Simon Pepper said:

This looks great and the way I have Gone for tonight’s imaging session. So it’s not a waste I’m hoping you have some j sight in the backfocus… in the redcat it’s 55mm but I can’t get that with the Samyang. Also looking at your setup here it’s no where near that. Is back focus important with a lens? Will I be ok with this setup? It’s a T2 adapter 25mm with l extreme inside plus 11mm spacer and 6.5mm I think to the sensor. 

Actually you have the correct spacing  The EOS adapter is actually 26.5mm thick, according to ZWO. With the 11mm ring and the 6.5mm of the camera, that makes 44mm, which is what the Samyang lens needs (for Canon). Just make sure you remove the 5mm spacer that comes with the adapter, this spacer is only needed with 12.5mm backfocus cameras (like the non-cooled models).

My setup is slightly different: the camera has 17.5mm of back focus, to which I added a 16mm thick filter drawer and a 10mm M48 spacer ring. Which puts me at 43.5mm. Since I use a 2-3mm filter inside, 1/3 of the filter's thickness gets me very close to the 44mm back focus distance required by the lens. My lens doesn't have a Canon mount, but a M48 threaded interface, by the way.

Hope that helps!

Edit: actually I'm not sure which version of the lens you use, I assumed Canon. For Nikon, it's basically the same, but the adapter is thicker (29mm) to work with Nikon back focus distance (46.5mm). But in any case, ZWO adapters are made to give you the exact distance you need for the mount you're using, so you just need the adapter, the 11mm spacer ring and your camera.

Everything is explained well here: https://astronomy-imaging-camera.com/product/nikon-t2-adapter-suitable-for-all-asi-cameras

I've been using the HS80C lately with my 130mm Newtonian and mount (about 8-9kg), and it was very stable. I can't comment on other models, but if it's anything like mine, then it's a great buy!  

21 hours ago, geeklee said:

Any news on when the official Samyang lens version might be arriving Pierre (if it still is)?  Or, do you have more details on the changes you made to support the RedCat version?  Thanks.

I'm afraid I haven't any news to share   Hopefully it will come soon!

What I can say about the changes, though, is that they are very minimal. Since the Samyang and the RedCat both use the same WO tube ring, the BlackCat kit can be used on both. Only the toothed ring/gear (not sure what it's called), that is attached to the RedCat's focuser, doesn't have the right diameter for the Samyang (pretty close though). 

In other words, both kits are exactly the same, except for the "toothed ring", which must match the diameter of the Samyang. 

I just switched from my Samyang to the RedCat, and that's a 5 min job. Both toothed rings remain attached to their respective scope, so there's really just 4 screws to mess with  Very happy with it so far!

20 hours ago, Simon Pepper said:

My 135 turned up yesterday but I have realised I do t have any rings or dove tails can anyone recommend any and save me sifting through this thread please? I have both a zwo and a dslr so ideally work with both. Thanks 

There are many ways indeed, to sum up what's been shared:

• Classic photography lens collars:
  • Plus: cheap, widely available, easy to use
  • Minus: you usually need to tweak it to add a millimeter or two. Also you can't fix anything on top (e.g. autoguider)
• William Optics RedCat 51 ring:
  • Plus: affordable (£39) and great quality, works out of the box, and you can add something on top. Good balance, since it holds the lens near its center of gravity. 
  • Minus: you can't change the aperture while the ring is holding the lens. But that's not a problem if you leave it always at the same aperture
• 3D Printed brackets (Astrokraken, Astrojolo, Astrodymium)
  • Plus: very lightweight, multiple rings allow a good grip on the lens, you can also change the aperture
  • Minus: can be a bit pricey, and it's plastic, so more risky than metal rings, rotating the lens might not be easy with some models
• Other types of rings:
  • Plus: very good quality, very secure (as nephilim showed), lots of mounting options for autoguider, focuser, etc.
  • Minus: very pricey (for Primaluce Lab rings, at least)

I tried the rings from Astrokraken and Astrojolo, but it didn't work out for me. The ring of my ZenithStar 61 also works well, but you can't add an autoguider on top, so it needs to be on the side and makes things complicated.

I finally ended up with the ring from William Optics, which is affordable and yet the best compromise between ease of use and mounting options, IMO. I even found that the 3D printed autofocus for the RedCat is also compatible with the Samyang (since they use the same ring system). Which means that I can install this on both my RedCat and the Samyang, all I need is to change the gear.

16 minutes ago, nephilim said:

Can anyone point me in the right direction for a good quality Bahtinov mask that will fit my 135. I bought a 3d printed one which cracked so I dont want to go down that road again (I wouldnt trust anything 3d printed really as my printed mounting system cracked as well a few weeks ago 🙄)

TIA
Steve

I'm using this one from William Optics. It's pricey, but it's solid and has the advantage to be transparent, which makes spikes more visible than opaque masks. It can also be used on your other scopes with a diameter up to 110mm, which is quite practical  

https://www.firstlightoptics.com/bahtinov-focus-masks/william-optics-bahtinov-mask-for-dew-shield-diameter-75mm-to-110mm.html

Nice setup and result!  

It looks like your ASIAIR just hung itself though!

Careful, I believe the pictures shows the mirrorless version of the lens (Sony E-mount). This version has built-in spacer, to compensate the space taken by the mirror of a DSLR, to which the collar seems to be attached.

Therefore I don't think this collar would work on the Canon/Nikon version of the Samyang, as you can see below there would be nowhere to attach it... Or perhaps between the focus ring and aperture ring, if the diameter allows it?

18 minutes ago, Toaster05 said:

@david_taurus83 Thanks for the reply. That could work for my needs, however I'm not so keen on applying tape to the lens itself as I use it for daytime photography too.

Though looking at what @Adreneline has posted I wonder if it would be viable for application on the ring itself?

I did like Adrenaline on a pair of 80mm ring to make them work on my scope that has 78mm inner diameter. It took a bit of trial and error, but I found the right adhesive felt bands and it works very well!

The advantage over tape, is that you modify the lens collar, not the lens. 

Try looking at the furniture section on Amazon, there are lots of felt pads and tape of any thickness, size, shape... 

To give you an idea, my rings have an 80mm inner diameter and the scope was 78mm. So I needed 2mm. However, I used 3mm thick felt to take the compression of the felt into account. I think another extra 0.5-1mm would have been even better, because with enough force I can still push the scope when the rings are closed. Although it's still secure enough like this.

So if you need 1mm, perhaps a 1.5mm should do the trick, so you have enough compression to hold the lens securely. But then again, some trial and error might be needed!

And of course, the thickness you need must be calculated with the existing felt removed, so you know what you need exactly!

Hope that helps  

20 minutes ago, Adreneline said:

Haha! I think maybe BlackCat mounts are about to get a boost! Nice arrangement Pierre - thanks for sharing!

Adrian

Yes, they're really nicely made! Compared to the rings used by Steve, I think the main advantage is that everything relies on the more solid William Optics tube ring, rather than 3D printed rings. Better for the peace of mind!

I'm currently beta testing a prototype for the Samyang, which basically is the same as the RedCat but with a different focus ring. It worked great yesterday and helped keep everything compact and tidy. I guess they should be available very soon!  

Thanks Lee! I wish I took the time to properly refocus, but well it was past midnight and I was exhausted from all the gymnastics I had to do for polar alignment   But yes - focus apart, it looks promising, and I can't wait to try again! 

It will indeed make my life easier (hopefully), I kind of lost the motivation to get out in the public parks... The cold, the curfews and now the sun setting very late aren't good motivators. But I'm getting closer!

I just found a screenshot of the drift alignment, with the frame of my window  I still have no idea how PHD could guide with such a tiny space, and through another window's glass... What an awesome software!

@nephilim My pleasure!  

Yesterday I spent some time trying to polar align my mount on my closed balcony. It is facing east exactly, and therefore I can't see Polaris... I've always wanted to try drift alignment, so I gave it a try yesterday. It wasn't easy, since you need to point the scope south, which i also don't see... and since I can't remove the windows, I had to get creative and drift align through the glass of one of them    But! It actually worked, and I got the mount (very) roughly polar aligned. I was quite surprised to be honest!

I'll try to improve the polar alignment now that I got the hang of it. But even with a rough polar alignment, my guiding was around 1.7"... which sounds like a miracle to me, given the conditions! 

It was also the first light for my ASI2600MC and the new Black Cat mount that I adapted to the Samyang. It worked flawlessly!

I made a few test exposures of the Sadr region, which is conveniently placed in the east right now. With this configuration, I can image targets up to ~60-65° of altitude, before the ceiling appears in the picture. I don't think I can image more than 2 hours in this configuration, but it's better than nothing!  

A 20 seconds exposure at gain 0, with the UV/IR cut filter:

Just before the ceiling took over, I switched to the Optolong L-eNhance and made a 2 min exposure. I didn't bother to restart the autofocus, so it's a bit blurry... And the stars aren't pinpoint, the limits of my polar alignment started to show! But I was expecting much worse honestly  So with a refined polar alignment, proper focus and the wide aperture of the Samyang, I'm sure I can make some very nice long exposures now!

If you stand away from your computer screen, these objects might appear more in focus!  

21 hours ago, nephilim said:

@Space Oddities I've just realised I haven't a clue how to fit this to my mount, will I need a different saddle as otherwise adding to my current saddle will have my set up turned 90 degrees (apologies if this is a daft question 🙂)

No problem, it's indeed an unusual way to mount your scope!

The dovetail itself is a standard vixen one, so you just attach it to your mount's saddle, like you do with your current setup.

Using this image as a reference:

• On the right side, there's a vixen saddle to which you can mount the Samyang with your existing dovetail (although a shorter one might be better)
• On the left side, the clamp allows you to mount the guide scope, or anything that has a standard finder dovetail (like the ASIAIR Pro)
• In the middle, you can attach the ASIAIR Pro (vertically), using the included 1/4" screw. This should provide a good balance and make the ASIAIR Pro close to everything. As you can see on the picture below, there should be enough room for the ASIAIR.

You do have to rotate manually your mount's saddle by 90°. That's how I did on my AZ-GTi, I'm not sure how this works on other mounts though... But I guess it's as easy as releasing the clutch and rotating the DEC axis 90°  

Below are 2 pictures of the setup I had, hope that helps!

You could use the cheaper dual plate from TS Optics, There should be enough room for an EAF between the lens and the Evoguide: https://www.teleskop-express.de/shop/product_info.php/language/en/info/p8315_TS-Optics-Parallelbefestigung---Doppelbefestigung-fuer-Teleskope--Tele-und-Leitfernrohre.html

The BlackCat mount is now available at FLO  

https://www.firstlightoptics.com/dovetails-saddles-clamps/proastrogear-black-cat-mount-connects-zwo-asiair-eaf-and-guide-scope-to-the-william-optics-redcat-51-telescope.html

I am in also touch with Lauri to see how this mount could be adapted to support the Samyang/Rokinon 135mm lens, as explained above. I am expecting some prototypes to see what would be the best fit.