Imaging with the Samyang 135mm f2

[nephilim]

1 hour ago, RobST said:

Looking forward to your images with the sharpstar 😀 i was torn between that and an esprit 100, i went for the esprit in the end 😀 might be here by Christmas 😂

@RobST I was originally looking at the Esprit 100, the WO GT81 IV & Sharpstar 100Q but so far it's the Sharpstar that has my vote plus no messing around with spacers for backfocus & no need to buy a flattener. I'll probably have enough to buy it in November but the lack of stock means I probably won't see it until around January. Just in time for crisp, clear winter nights....Hmmmm we'll see 🤔😒

Edited August 19, 2021 by nephilim

[RobST]

1 hour ago, nephilim said:

@RobST I was originally looking at the Esprit 100, the WO GT81 IV & Sharpstar 100Q but so far it's the Sharpstar that has my vote plus no messing around with spacers for backfocus & no need to buy a flattener. I'll probably have enough to buy it in November but the lack of stock means I probably won't see it until around January. Just in time for crisp, clear winter nights....Hmmmm we'll see 🤔😒

Lol like the heatwave 😂😂

[tomato]

3 hours ago, Tomatobro said:

This might have been posted elsewhere but for reference a GT2 2mm pitch tooth belt engages with the focus ring and allows for a Skywatcher DC focus motor to be used. Brackets to support the motor are need to be made to suit the mounting rings used

Looks like a blower drive from a 60’s fueler…👍

[Budgie1]

4 hours ago, tomato said:

Looks like a blower drive from a 60’s fueler…👍

Na, Adrian's got that covered, you can nearly smell the Nitro! 🤣

On 08/05/2021 at 02:11, Adreneline said:

My latest Samyang configuration. The 294 has an Astronomik L2 filter fitted in the 11mm spacer and the 135 focuses in the middle of the ‘L’.

Adrian

Edited August 19, 2021 by Budgie1

[tomato]

Far out, it just needs some zoomie headers…😎

[Space Oddities]

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!

[geeklee]

1 hour ago, Space Oddities said:

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). 

Ah, understood.  Did you print a new ring?  The way the gears mesh looks precise enough that some cleverly placed foam on the inside of the ring might not be enough (unless the Samyang is actually bigger in which case, no dice at all!).

1 hour ago, Space Oddities said:

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 

That would be an attractive point for people with these two - with you, me and @Adreneline that's three potentials anyway  

My RedCat setup is currently a fairly clunky arrangement not really suitable for the BlackCat but my Samyang setup could do with losing some weight and would be compatible. Thanks for the info anyway 👍

[nephilim]

I'd love it if a dedicated EAF became available for the Samyang as I really struggle manually focussing. I use the ASIair but it's focus routine is absolute pants (everything else it does though is superb), half the time the HFD is showing 10 which is as out of focus as its possible to be (even though the stars on my tablet screen show themselves as fairly tight) the other half its bouncing around from between 2 or 3 point something to 8 or 9 point something & again the stars on the screen look stable. 

I've completely given up on using that method & manually focus instead, so far this has more or less been ok albeit very time consuming but sometimes it's only just out so has ruined an image.

An automated focuser would be a god send. @Adreneline has tried to explain to me in depth the process of a home brewed one using the ZWO EAF, sending links to the company he uses for timing belts etc but my brain tends to stop working. I'm very good (well....I think so 😂) at 'learning by doing'. As in watching someone do it the first time & simply following suit. This has worked well for me with the likes of slowly learning PixIsight but when faced with just written instruction all bets are off 😒

Talking of focusing, I'd like to thank @Space Oddities for pointing me in the right direction for the WO Bahtinov Mask for the 135 (although not specifically for the Samyang, it's adjustable & makes for a perfect fit)

Another SGL member @Ande had mentioned it to me a while back but I'd forgotten all about it. I initially baulked at the price of it but then realised it will also fit my upcoming 'winter scope' so it made the price easier to swallow. It arrived yesterday from FLO & I have to say it's a really well made, solid bit of kit with nice good quality brass (I think) adjustment screws, also been acrylic it will make those diffraction spikes really stand out.

Steve

[powerlord]

On 23/08/2019 at 10:50, 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

So.. maybe I've been doing it wrong, but I just take one master flat with L filter and use it for everything ?

stu

[powerlord]

On 20/08/2021 at 14:58, nephilim said:

I'd love it if a dedicated EAF became available for the Samyang as I really struggle manually focussing. I use the ASIair but it's focus routine is absolute pants (everything else it does though is superb), half the time the HFD is showing 10 which is as out of focus as its possible to be (even though the stars on my tablet screen show themselves as fairly tight) the other half its bouncing around from between 2 or 3 point something to 8 or 9 point something & again the stars on the screen look stable. 

I've completely given up on using that method & manually focus instead, so far this has more or less been ok albeit very time consuming but sometimes it's only just out so has ruined an image.

An automated focuser would be a god send. @Adreneline has tried to explain to me in depth the process of a home brewed one using the ZWO EAF, sending links to the company he uses for timing belts etc but my brain tends to stop working. I'm very good (well....I think so 😂) at 'learning by doing'. As in watching someone do it the first time & simply following suit. This has worked well for me with the likes of slowly learning PixIsight but when faced with just written instruction all bets are off 😒

Talking of focusing, I'd like to thank @Space Oddities for pointing me in the right direction for the WO Bahtinov Mask for the 135 (although not specifically for the Samyang, it's adjustable & makes for a perfect fit)

Another SGL member @Ande had mentioned it to me a while back but I'd forgotten all about it. I initially baulked at the price of it but then realised it will also fit my upcoming 'winter scope' so it made the price easier to swallow. It arrived yesterday from FLO & I have to say it's a really well made, solid bit of kit with nice good quality brass (I think) adjustment screws, also been acrylic it will make those diffraction spikes really stand out.

Steve

The 10 quid one from the seller on ebay is great honestly. it gives very nice X pattern, focus in seconds. And did I mention it's only 10 quid..

I printed that mount/raf for mine (see previous post) - and the thingiverse link has the BOM of the bearings, belt, pulley wheel you need. total parts cost about 10 quid. Obviously you need a 3d printer. but the one I use cost 220 quid. so print 1 of these, save yerself 100 quid, and you've already half way to ROI!

I mainly printed it for when/if using with asi1600 as then it's going to need to eaf between filters itself. If you are not refocusing, it really is not required.

however, if you want a super super cheap and easy way to electric focus - just do what I did in another post:

 

stu

[Adreneline]

2 hours ago, powerlord said:

So.. maybe I've been doing it wrong, but I just take one master flat with L filter and use it for everything ?

Hi Stu,

Well I know some would advocate doing just that but I'm not one of them. I have found there to be significant differences between flats taken with Ha, OIII and SII when compared with L. I am very much in the camp of having a master flat for each filter. I have my filters in a sealed EFW (on my RedCat) and I never (or very rarely) breakdown the image train so having taken flats for each filter I just keep using the same flats time after time (along with their matching Dark-Flats).

My Samyang currently has a manual filter drawer fitted but even there I would only repeat taking flats if I noticed dust bunnies on the subs. Whenever I change a filter I always give it a good blast with the rocket-blower and hope for the best!

Good luck.

Adrian

[Adreneline]

On 20/08/2021 at 14:58, nephilim said:

WO Bahtinov Mask for the 135

As an aside Steve when you buy your RedCat (you're bound to get one eventually  ) you will find the RedCat BM fits perfectly inside the Samyang lens hood.

Perfick!

Adrian

[Petrol]

On 20/08/2021 at 14:58, nephilim said:

I'd love it if a dedicated EAF became available for the Samyang as I really struggle manually focussing. I use the ASIair but it's focus routine is absolute pants (everything else it does though is superb), half the time the HFD is showing 10 which is as out of focus as its possible to be (even though the stars on my tablet screen show themselves as fairly tight) the other half its bouncing around from between 2 or 3 point something to 8 or 9 point something & again the stars on the screen look stable. 

I've completely given up on using that method & manually focus instead, so far this has more or less been ok albeit very time consuming but sometimes it's only just out so has ruined an image.

An automated focuser would be a god send. @Adreneline has tried to explain to me in depth the process of a home brewed one using the ZWO EAF, sending links to the company he uses for timing belts etc but my brain tends to stop working. I'm very good (well....I think so 😂) at 'learning by doing'. As in watching someone do it the first time & simply following suit. This has worked well for me with the likes of slowly learning PixIsight but when faced with just written instruction all bets are off 😒

Talking of focusing, I'd like to thank @Space Oddities for pointing me in the right direction for the WO Bahtinov Mask for the 135 (although not specifically for the Samyang, it's adjustable & makes for a perfect fit)

Another SGL member @Ande had mentioned it to me a while back but I'd forgotten all about it. I initially baulked at the price of it but then realised it will also fit my upcoming 'winter scope' so it made the price easier to swallow. It arrived yesterday from FLO & I have to say it's a really well made, solid bit of kit with nice good quality brass (I think) adjustment screws, also been acrylic it will make those diffraction spikes really stand out.

Steve

What are those lens rings if you don't mind me asking? They look much better than 3d printed.
Pete

[nephilim]

6 hours ago, Petrol said:

What are those lens rings if you don't mind me asking? They look much better than 3d printed.
Pete

@Petrol I use PrimaluceLab for holding everything together apart from the top  bar on the 135 which is WO

I don't trust 3D printed rings after one cracked when I overtightened it slightly. Primaluce gear is very high quality but fairly expensive. These are the rings https://www.firstlightoptics.com/tube-rings/primaluce-lab-80mm-plus-tube-rings-for-airy-apo65f.html

Edited August 22, 2021 by nephilim

[nephilim]

6 hours ago, Petrol said:

What are those lens rings if you don't mind me asking? They look much better than 3d printed.
Pete

[powerlord]

Just sticking up for 3d printed gear a bit (as I've been 3d printing for 10 years). Most of the stuff you buy, and the stuff I printed above are done in PLA. This is a very high rigidity plastic, but it does not deform well - it will just crack.

It therefore, does not need to be tightened more than hand tight if there are screws in it. I hate to say if it cracked it was user error, because it could be the part was not good, but it is more likely you didn't realise that PLA is not like nylon - it will not just start to deform a bit and spring back when tightened too much.

I have printed most of my bahtinov masks myself other than the massive 8" and 10" ones - and they all work perfectly.

I also use 3d printed parts as structurally engineered parts in lots of things. They just need to be used correctly.

I am not for one moment saying those lovely CNCed aluminium parts are not superior - they clearly are - but like lots of astro stuff the premium you pay is usually well beyond what the part should cost. 2-300 quid. And I don't think any engineer would argue with me saying they are vastly over engineered.

Just don't want to put other off from 3d printing - it really will save you the cost of the printer in a few prints in this hobby imho. And these days, there really is little you need to learn. I got a new 3d printer last week:

https://www.amazon.co.uk/gp/product/B07JN7HFYS/ref=ppx_yo_dt_b_asin_title_o03_s01?ie=UTF8&psc=1

this is about the best in that price range. It takes 15 mins from getting it, to your first print. And assuming you are not wanting to design your own stuff initially, you will be printing your first part from thingiverse in another 15 mins.

1kg of PLA is 15 quid and will do you tons of parts.

just my 2c 🤓

[nephilim]

22 hours ago, Adreneline said:

As an aside Steve when you buy your RedCat (you're bound to get one eventually  ) you will find the RedCat BM fits perfectly inside the Samyang lens hood.

Perfick!

Adrian

Thanks Adrian, thats good to know 'IF' I ever buy the Redcat 😂 I'm in the process of saving for the Sharpstar 100Q II at the moment & luckily the WO BM that i've just bought will also adjust to fit that. Two for the price of one, Its very rare that something like this happens & you can actually save money on astro kit 😃

[nephilim]

12 hours ago, powerlord said:

Just sticking up for 3d printed gear a bit (as I've been 3d printing for 10 years). Most of the stuff you buy, and the stuff I printed above are done in PLA. This is a very high rigidity plastic, but it does not deform well - it will just crack.

It therefore, does not need to be tightened more than hand tight if there are screws in it. I hate to say if it cracked it was user error, because it could be the part was not good, but it is more likely you didn't realise that PLA is not like nylon - it will not just start to deform a bit and spring back when tightened too much.

I have printed most of my bahtinov masks myself other than the massive 8" and 10" ones - and they all work perfectly.

I also use 3d printed parts as structurally engineered parts in lots of things. They just need to be used correctly.

I am not for one moment saying those lovely CNCed aluminium parts are not superior - they clearly are - but like lots of astro stuff the premium you pay is usually well beyond what the part should cost. 2-300 quid. And I don't think any engineer would argue with me saying they are vastly over engineered.

Just don't want to put other off from 3d printing - it really will save you the cost of the printer in a few prints in this hobby imho. And these days, there really is little you need to learn. I got a new 3d printer last week:

https://www.amazon.co.uk/gp/product/B07JN7HFYS/ref=ppx_yo_dt_b_asin_title_o03_s01?ie=UTF8&psc=1

this is about the best in that price range. It takes 15 mins from getting it, to your first print. And assuming you are not wanting to design your own stuff initially, you will be printing your first part from thingiverse in another 15 mins.

1kg of PLA is 15 quid and will do you tons of parts.

just my 2c 🤓

@powerlord I completely agree with you there. I didn't realise that there would be no 'give' in the rings so with me putting a little too much pressure on when tightening, this caused it to crack. The Primaluce kit is very expensive & probably over engineered but using to secure my camera, lens etc has given me confidence that the gear they're 'looking after' will be safe 🙂

Steve

[Petrol]

On 22/08/2021 at 05:48, nephilim said:

@Petrol I use PrimaluceLab for holding everything together apart from the top  bar on the 135 which is WO

I don't trust 3D printed rings after one cracked when I overtightened it slightly. Primaluce gear is very high quality but fairly expensive. These are the rings https://www.firstlightoptics.com/tube-rings/primaluce-lab-80mm-plus-tube-rings-for-airy-apo65f.html

Thanks 👍

[powerlord]

Here's the Heart and Soul... 300 subs at 30 seconds. No filters. Canon 6d.

I can't say I'm that impressed tbh. I should have used L-extreme or a UHC filter. Lots and lots of light pollution gradients to get rid of.. and maybe that's why I couldn't pull out anything else..

Edited August 25, 2021 by powerlord

[RobST]

Looks great to me 😀

[Simon Pepper]

On 19/08/2021 at 14:29, Space Oddities said:

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.

 

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. 

[Laurin Dave]

If I remember correctly back focus should be 44mm for a Canon fit 46.5 mm for a Nikon fit plus 1/3rd of any  filter thickness you have between the lens and the sensor

[nephilim]

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. 

@Simon Pepper Back focus with a lens is just as important as with a telescope. From the info you've given, you've only got 42.5mm so you'll need another 4.1mm to get to where you need to be. That's taking into account the extra 0.6mm for your filter. Also be aware that once you take that filter out or replace with a different filter you'll need to recalculate the thickness of the new filter (add ⅓ of the filter thickness to the original backfocus (44mm with the Samyang)  its that precision dependant that even by been 0.1mm out will put you out of focus.  You don't mention why you can't achieve the correct back focus? If it's just a case of a lack of spacers, they're readily available online https://www.harrisontelescopes.co.uk/acatalog/baader-t-2-adjustment-spacer-ring-set.html?gclid=Cj0KCQjwsZKJBhC0ARIsAJ96n3Ua0J60FTQW3HGQvRhKTx8w-BMOPCe32JcrMNPjC2VX2yZkorJpffUaAhV5EALw_wcB There are cheaper but these are good quality just make sure the diameter matches your camera. I've also got the L-eXtreme filter attached to the annular ring inside the 11mm spacer, for this filter you also need to add an extra 0.6mm as the filter thickness is 1.8mm.

Steve

Edited August 25, 2021 by nephilim

[Space Oddities]

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

Edited August 25, 2021 by Space Oddities