Takahashi Epsilon Dual Rig - Need Advices - Forums

Hi astro-friends,

I am seeking for advices for a new setup and I would be grateful if you could share your thoughts and your wisdom with me

.

I am expecting to get a new scope, i.e. Takahashi epsilon 160ed, by end of this year, and to fully take advantage of the beast I plan to use it along with a full frame camera.

While eagerly waiting for the new equipment to come, we have decided with a friend of mine to go a bit crazy and to setup a so-called "dual rig" permanently installed in my backyard observatory.

In the best scenario, we would just duplicate the equipment, namely to get another e-160ed with a full frame sensor, etc. However, we have been informed that due to the high number of back orders the lead time might be quite important - so we shouldn't expect anything this year and resellers are struggling to give us an ETA

. We are going through very difficult times....

Since many epsilon 130d are on the market, and provided we are not willing to wait a year before getting another sample, we are thinking about the epsilon 130d as an alternative. Below image depicts two FOVs:

red frame = e-160ed with the ASI 6200
yellow frame = e-130d wit the ASI 6200

Worth mentioning that the primary purpose of this setup is to have two scopes shooting at the same target, at the same time (no brainier I believe).

As per the below FOVs, and since the two scope share similar architectures (e-160ed has better field performances though),

Anything that we are missing or not considering ?
Should we wait for the same model, i.e. e-160ed ?

Lots of questions, but let's keep them short for the time being.

A big thank you in advance for your advices.

Kind regards,
Aygen

Well, good luck in your endeavour. I'm not wedded to Tak so I'd chose a different route but it's your jig so have fun in putting everything together. I'm sure you won't be disappointed either way.

Thanks Andrea for chiming in. What would choose then ? Let us know 👍

You will be cropping the 130 frame to the 160 FOV I assume. That would effectively make the focal lengths of the two scopes identical and the E130D would behave as an f/4 scope.

Being reflectors, you'd also need to match the orientation of the spider vanes of both scopes with respect to the base if you want the diffraction spikes to overlap. This is irrespective of whether you are using two E-160EDs or a E-130D and E-160ED.

We also thought about your last very valid points, i.e the spider orientation. Going to be fun either way

I think it couldn’t hurt to drop some emails. Meanwhile, I have already asked Tak to put me on the list - who knows - someone may finally decide not to go ahead.

I owned a E-130D. Mine was supplied without an aperture mask. This resulted in triangular shaped stars due to edge artifacts from the mirror (I did not know this was the reason at the time). If you are getting a used E-130D, make sure it comes with an aperture mask.

Aygen:
Thanks Andrea for chiming in. What would choose then ? Let us know 👍

One idea would be for a couple of 300/400 mm lenses shooting at f/2.8. But that may require a downsizing of your ambitions of shooting FF and tricky if you plan going mono/filters. Otherwise, I'd plump for a pair of newt @ f/4 with a reducer corrector to bring them down close to your chosen focal length.

Good to know, Arun. Thank you.
Looking forward to hearing others thoughts.

andrea tasselli:
Aygen:
Thanks Andrea for chiming in. What would choose then ? Let us know 👍

One idea would be for a couple of 300/400 mm lenses shooting at f/2.8. But that may require a downsizing of your ambitions of shooting FF and tricky if you plan going mono/filters. Otherwise, I'd plump for a pair of newt @ f/4 with a reducer corrector to bring them down close to your chosen focal length.

Shooting at f/3.3 with a FF is already challenging - don’t want to imaging how crazy it should be @ f/2.8. But thanks to another thread here on AB (kudos to Bill and Chris), it should be all fine with a bit of patience

I have an e-160ED paired with an FSQ-85. An APS-C on the Epsilon and 4/3rd’s on the refractor line up quite well with the same FOV.

I was thinking of getting an e-130D to replace the FSQ-85. I’d also only run the 4/3rds on it. FOV will again be very similar. I think you’d be disappointed with a full frame
on the e-130D. But if it’s not the one gathering the RGB star data then no issues.

The issue with the spider vanes not
lining up is fairly easily solved if you do all the RGB stars on one scope. Then use StarXTerminator to pull them out. Then it’s up to you how you’d like to gather the rest of the data. You’ll be removing the stars so it doesn’t matter about those spikes lining up. I’ve been very impressed with StarXTermintor so far.

I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

I’ll keep you posted how I go with the second Epsilon.

Thank you Tom, great advices, never thought about it (RGB stars, etc.).

Finally, I will get two E-160ed, same camera (full frame), etc. so that I won't bother much about "FOV issues" (even though it's not really an issue).

Yeah, let me know once you have a second epsilon - that's going to be crazy efficient once up and running !

Tom Dinneen:
I have an e-160ED paired with an FSQ-85. An APS-C on the Epsilon and 4/3rd’s on the refractor line up quite well with the same FOV.

I was thinking of getting an e-130D to replace the FSQ-85. I’d also only run the 4/3rds on it. FOV will again be very similar. I think you’d be disappointed with a full frame
on the e-130D. But if it’s not the one gathering the RGB star data then no issues.

The issue with the spider vanes not
lining up is fairly easily solved if you do all the RGB stars on one scope. Then use StarXTerminator to pull them out. Then it’s up to you how you’d like to gather the rest of the data. You’ll be removing the stars so it doesn’t matter about those spikes lining up. I’ve been very impressed with StarXTermintor so far.

I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

I’ll keep you posted how I go with the second Epsilon.

I don't have high end names of scopes, but i am thinking to do that kind of imaging to collect stars data from one scope and leave the rest with another scope, i really don't mind spikes at all, but if i will use two different reflectors then definitely difficult to line up, so i decided that i will only keep stars from RGB with one scope be it a refractor or a reflector, i will try to have each depends on targets, not all targets i like the spikes with, for example M45 and Andromeda both i prefer without spikes, and also Rosette and similar nebulae, while galaxies far distant and clusters rather than M45 i like with spikes more.

I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

Did you consider the TGAD from ADM ? Based on my recent exchange with the owner (ADM), you should be all good with the total weight.

Your motivation is the same as mine. I’d recommend you look at tilt adjustment as well. I’ve had success with a Gerd Neumann CTU. Other use the Octopi and Photon Cage. I like the look of the Photon Cage. Having separate backspace is a nice feature. You’ll also likely need to replace the focuser. You’ll have hit the lottery if both scopes have focusers that hold collimation when rotated. If rotation is not something you do often and you are happy to collimate and redo tilt adjustment when you do then stock focusers might just work for you. Picking the right electronic focuser is also something to consider. I’ve had so so experience with my ZWO EAF and the stock focuser. For example forget about filter offsets. If you never want to worry about focusers and tilt from rotation then upgrade to the Optec Leo (which has an ibuilt tilt mechanism so you can get the focus tube square to the secondary).

Aygen:
I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

Did you consider the TGAD from ADM ? Based on my recent exchange with the owner (ADM), you should be all good with the total weight.

I looked at it. I think 9kgs the limit. The e-160ED is 7kgs and with rings, plate, camera, filterwheel I’d be hitting 9.5kgs. If ADM have said their 9kg limit is conservative then that changes things.

Tom Dinneen:
Aygen:
I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

Did you consider the TGAD from ADM ? Based on my recent exchange with the owner (ADM), you should be all good with the total weight.

I looked at it. I think 9kgs the limit. The e-160ED is 7kgs and with rings, plate, camera, filterwheel I’d be hitting 9.5kgs. If ADM have said their 9kg limit is conservative then that changes things.

I will need to check again with ADM, but I was told some guys put their C14 on it ! In any cases, we will manage to align them. We’re not the first setting up a dual rig

Tom Dinneen:
Your motivation is the same as mine. I’d recommend you look at tilt adjustment as well. I’ve had success with a Gerd Neumann CTU. Other use the Octopi and Photon Cage. I like the look of the Photon Cage. Having separate backspace is a nice feature. You’ll also likely need to replace the focuser. You’ll have hit the lottery if both scopes have focusers that hold collimation when rotated. If rotation is not something you do often and you are happy to collimate and redo tilt adjustment when you do then stock focusers might just work for you. Picking the right electronic focuser is also something to consider. I’ve had so so experience with my ZWO EAF and the stock focuser. For example forget about filter offsets. If you never want to worry about focusers and tilt from rotation then upgrade to the Optec Leo (which has an ibuilt tilt mechanism so you can get the focus tube square to the secondary).

I will go with the LEO, Octopi, Pegasus Indigo and Indigo OAG. But I will need to be patient since the next delivery for the Epsilon is due in April 2023.

Sounds like you’ve already got this well thought out. They are beasts of a machine. It’s my first reflector after 10-12 years of refractors. I’m just floored by the performance and that’s coming from a stable full of Takahashi scopes. They take a bit of work to get everything lined up individually and then as a dual setup but boy once you do it’s so worth it. The e-160ED is two and a half times faster than the FSQ-85 which is no slouch. Having that speed is an eye opener. Now I want even more speed.

Tom

Aygen,

All good comments above. I have three scopes from William optics FLT132, FLT91 and Z61 and I match the field of views with my two cameras ASI6200 and ASI2600. I shoot the color with the lower resolution scope and luminance or Ha with the higher resolution scope. The set ups are tandem mounted and aligned just as you plan. It's a great way to collect more data especially if you are starved of clear dark skies, so you will have fun.

My only comment is I ran with different FOV a couple of times and while it works there was something about losing all the data in the wider field due to the lack of overlap. As a result I now just make sure that with the camera, reducer and scope set up I have pretty much exactly the same field of view. So at least for me it was more rewarding and less hassle especially with larger nebula or regions where the smaller field of view just doesn't quite work!

My advice would be to wait for the E160 so you have to identical setups or find a temporary perhaps lower price scope up that gives the same ~ 500 mm FL that is available then switch to the E160 when it arrives.

Have fun I've been tandem imaging for about a year now and really love the results.

John

Tom, I hear your, and I am fully with you.

I still have that TOA which I intend to keep anyway since I am more than happy despite this latter being a bit slow.

Reflectors are totally new for me but I am looking forward to it ! Faster scopes are definitely what I need here in Switzerland given the very bad weather !

John Noble:
Aygen,

All good comments above. I have three scopes from William optics FLT132, FLT91 and Z61 and I match the field of views with my two cameras ASI6200 and ASI2600. I shoot the color with the lower resolution scope and luminance or Ha with the higher resolution scope. The set ups are tandem mounted and aligned just as you plan. It's a great way to collect more data especially if you are starved of clear dark skies, so you will have fun.

My only comment is I ran with different FOV a couple of times and while it works there was something about losing all the data in the wider field due to the lack of overlap. As a result I now just make sure that with the camera, reducer and scope set up I have pretty much exactly the same field of view. So at least for me it was more rewarding and less hassle especially with larger nebula or regions where the smaller field of view just doesn't quite work!

My advice would be to wait for the E160 so you have to identical setups or find a temporary perhaps lower price scope up that gives the same ~ 500 mm FL that is available then switch to the E160 when it arrives.

Have fun I've been tandem imaging for about a year now and really love the results.

John

John,

Thank you so much for chiming in.

As part as my project, we decided to get two same scopes (e-160ed), also for the reasons you mentioned.

Out of curiosity, how did you align the three scopes ? @ Tom and I were discussing about different devices but some of them have some limitations with regards to the overall weights the can handle.

Aygen

Just for clarity I only use two scopes at a time and I align them using a three point scope ring on the smaller scope. Its not perfect but it's good enough I tweak it at the start of each session. I will eventually go for the ADM adjuster but it's not essential.

Thanks

John

I have dual imaged before with a couple of setups. Most recently I ran an AP130GTX and an AP Stowaway, side by side. I was collecting Lum with the GTX at a higher resolution and RGB with the stowaway.

In my opinion… and this is from my experience… It's not that much fun dual imaging. I ended up deciding to drop the idea and instead setup two separate setups. A shorter focal length and a longer focal length. I can run both at the same time, on separate targets. I'm using the e160ED+QHY600 on one setup and 130GTX+QHY268 on the second setup. I get to image two separate targets and it's always fun!

Just food for thought….

We know that this journey will require patience and iteration to get where we intend to get. It’s going to be challenging but also very rewarding once up and running.

To operate it successfully, I will use the array version of Voyager. Nothing beats it from my perspective.

I will for sure keep this post updated in a few months to share our progress.

Tom Dinneen:
Aygen:
I’m also toying with idea of a second e-160ED. But I think the weight will exceed the JTB alignment saddle I have. I think that would also exceed the ADM Max HD. Have you considered how you are going to align the second scope?

Did you consider the TGAD from ADM ? Based on my recent exchange with the owner (ADM), you should be all good with the total weight.

I looked at it. I think 9kgs the limit. The e-160ED is 7kgs and with rings, plate, camera, filterwheel I’d be hitting 9.5kgs. If ADM have said their 9kg limit is conservative then that changes things.

TOM, where did you retrieve this info, i.e. 9kg limitation ? I wasn't able to find anything on their website, but as written in my above post, ADM owner told me that I shouldn't be worried about it since some customers put their C14 on it. Of course, I can't confirm it. However, I have seen people with FSQ106 on it.

Takahashi Epsilon Dual Rig - Need Advices

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