Perfect TSA-120 Setup

[PeterWar]

Greetings guys,

 

After many years happily owning Reflectors and SCT, I've decided to try to give me a threat and buy a nice refractor.

Presently, I now run a professional observatory in Europe and I do plenty of outreach activities with most of my current equipment (except for my premium eyepieces, those I've kept at home).

So the plan is now to leave all the scopes at the Observatory, that is located in an International Dark Sky Park and buy a new premium telescope to be used for visual observations at my sub-urban home.

Contrast and perfectly corrected optics do take preference over aperture in this situation, the scope would sit in the living-room, just a few meters away from the terrace, so aesthetics need to be considered as well. A grab-and-go telescope is most preferable too, I don't need goto. The scope will be used for visual for moon, planets and some wide fields.

 

After many candidates reviewed the Takahashi TSA-120 is my prime candidate, It's ahead of the Astrophysics and TeleVue refractors in any strehl rating I've found.

 

I would appreciate help on deciding the following:

 

 

1- Optional flatteners

 

The scope is intended for visual use, would eyepieces like my 17mm Nikon NAV-SW benefit from using the TOA35-FL flattener? would the flattener vignette the 31mm Nagler?

 

 

2- Focuser:

Should I order it standard or with the feather touch focuser? I've heard that the feather touch would be preferred  when it comes to holding heavy eyepieces like my 31mm Nagler, but my understanding is that if I choose to go this route I won't be able to screw in the Takahashi TSA-120 flattener or the focal reducer if I ever decide to buy them, is that correct?

 

 

3- Mount and Tripod

I'm leaning towards using a DM-4 mount.

 

I would like a grab-an-go alt-az mount that doesn't look ugly and would be enough to carry the TSA-120 with heavy eyepieces or a binoviewer. I think I would prefer wood over metal, although I like the looks of the T-Pod tripod.

 

 

Any input you may have on this would be greatly appreciated.

 

Thank you very much for your time!

[MarsG76]

totally logical decision... I'm tempted by refractors too.

 

[michael.h.f.wilkinson]

The TSA-120 is a great scope by all accounts, good choice, I would say. I have a field flattener with my APM 80mm F/6, but only ever use that for imaging. Getting the distance to the image plane (field stop) of the EP right is a bit of a faff, and I didn't notice any benefit from it, either in the LVW 42 and the Nagler 31T5 (a.k.a. Panzerfaust). I didn't notice any vignetting in either EP either. It is a very much smaller scope than the TSA-120, but given that its focal length is shorter, this suggests the radii of curvature of the surfaces are shorter, which should increase field curvature (see the equation of Petzval field curvature here). If my 480m focal length has no noticeable field curvature for visual observation, the TSA-120 should be fine for visual in that respect. I expect the eye can accommodate sufficiently to correct for the effect.

[iPeace]

I feel I can only contribute with regard to the tripod and possibly the mount.

Berlebach offer a very nice wooden tripod, the PLANET, with (as a configuration option) a mounting plate suitable for DM-4 or DM-6. Its 3/8" 16 tpi centre/center bolt is also suitable for other mounts, such as my own choice, the Losmandy AZ8.

Mine has the optional double leg clamps and rubber feet installed.

EDIT: With many thanks to @Doc for providing the information I needed at the time to decide on this tripod.

The Losmandy AZ8 is a very well built and uncomplicated alt-az mount with manual slow motion control. You can of course loosen the clutches to pan around freely when desired. The picture above shows it with two (optional) additional risers for extra height should that be needed.

I like the look of it as well, but that's a matter of taste.

https://www.berlebach.de/?bereich=details&id=350&sprache=english

[DirkSteele]

1 hour ago, iPeace said:

 

 

Where did you acquire the pillar extension?  That could be rather useful for me considering I have a 1200mm focal length refractor on the way.  Thanks

[iPeace]

2 hours ago, DirkSteele said:

Where did you acquire the pillar extension?  That could be rather useful for me considering I have a 1200mm focal length refractor on the way.  Thanks

First, be aware that the "pillar" you see is composed of stacked elements. The top one is an integral part of the AZ8 head; the bottom two are these jobs:

I got one from TS in Germany, but it seems they no longer have them in stock. I got the other from Astromarket in Belgium:

https://www.astromarket.org/monteringen-en-toebehoren/az-monteringen/az8-alt---az-mount-with-tripod945835

Alternatively, I'm sure any reputable Losmandy dealer can source one for you.

 

[PeterWar]

Gentlemen, thank you so very much for your very informative repplies.

15 hours ago, MarsG76 said:

totally logical decision... I'm tempted by refractors too.

 

MarsG76, we almost have the same telescope setup, I have an Orion X14G and a Nextar 8 SE, an APO would be the totaly logical next choice for both of us.

 

 

14 hours ago, michael.h.f.wilkinson said:

The TSA-120 is a great scope by all accounts, good choice, I would say. I have a field flattener with my APM 80mm F/6, but only ever use that for imaging. Getting the distance to the image plane (field stop) of the EP right is a bit of a faff, and I didn't notice any benefit from it, either in the LVW 42 and the Nagler 31T5 (a.k.a. Panzerfaust). I didn't notice any vignetting in either EP either. It is a very much smaller scope than the TSA-120, but given that its focal length is shorter, this suggests the radii of curvature of the surfaces are shorter, which should increase field curvature (see the equation of Petzval field curvature here). If my 480m focal length has no noticeable field curvature for visual observation, the TSA-120 should be fine for visual in that respect. I expect the eye can accommodate sufficiently to correct for the effect.

Michael, you seem to have an in-depth understanding of this subject. How do you think the TSA-120 would compare to the TeleVue127NIS? EDIT: Have you seen the Airylab reports?

14 hours ago, iPeace said:

I feel I can only contribute with regard to the tripod and possibly the mount.

Berlebach offer a very nice wooden tripod, the PLANET, with (as a configuration option) a mounting plate suitable for DM-4 or DM-6. Its 3/8" 16 tpi centre/center bolt is also suitable for other mounts, such as my own choice, the Losmandy AZ8.

 

 

 

Mine has the optional double leg clamps and rubber feet installed.

EDIT: With many thanks to @Doc for providing the information I needed at the time to decide on this tripod.

The Losmandy AZ8 is a very well built and uncomplicated alt-az mount with manual slow motion control. You can of course loosen the clutches to pan around freely when desired. The picture above shows it with two (optional) additional risers for extra height should that be needed.

I like the look of it as well, but that's a matter of taste.

 

https://www.berlebach.de/?bereich=details&id=350&sprache=english

iPeace, you've been able to find just the right tripod for my needs, it's great that I can source it in Europe!

[MarsG76]

3 hours ago, PeterWar said:

MarsG76, we almost have the same telescope setup, I have an Orion X14G and a Nextar 8 SE, an APO would be the totaly logical next choice 

I also have a 80mm f6.25 refractor piggybacked on my 8SE OTA. Mainly used for wide shot and large objects.

It's not a triplet but it's very good quality for the price.

To me the Takashi 106 looks very tempting.

[michael.h.f.wilkinson]

9 hours ago, PeterWar said:

Michael, you seem to have an in-depth understanding of this subject. How do you think the TSA-120 would compare to the TeleVue127NIS? EDIT: Have you seen the Airylab reports?

I have no experience with either scope. The only really big quality refractor I have looked through is Olly's TEC 140. Superb scope, but I must honestly say the views through his 20" Dob hit the TEC for six. I have looked at the AiryLab reports, and note that there is a lot of variation in Strehl values from different instances of the "same" optics. The two NP127 (no-is) vary quite a bit, as do the three NP127is scopes. The slightest knock can mar alignment ever so slightly and affect Strehl a lot. Likewise, the listed APM 80mm F/6 is the same as teh TS of the same specs, but the Strehl of the APM is listed as lower than that of the TS, which in this instance scored a very creditable 0.957 at 543 nm (vs 0.91 for the APM). I am not sure about the Strehl value of my APM scope, I know I really enjoy the views and images it gets me. The TV NP127 has the dge in aperture, and seems to be competitive in quality with the (single) TS-120 instance listed. However, given the variations in performance between models, I doubt the differences are significant (or even visible to a skilled observer).

[PeterWar]

I wish feather touch focusers would come at a similar color palete than the TSA-120, honestly the only thing that's keeping me from ordering one is the thrown together look of the feather touch version.

[PeterWar]

I'm now trying to ascertain how much of a field curvature would I have on the TSA-120, and if it would be noticiable for visual use under 1.5 arcsecond seeing.

My idea was to buy the TOA35-FL for visual use, it's even advertised as an improvement in views on wide angle 2" eyepieces. I'm concerned however that this might introduce vignetting in the 31mm Nagler. The Nagler has a 42mm field stop and Takahashi specification for both the TOA-35 reducer and flattener account for a 40mm image circle (I presume this to be equivalent to the field stop).

[nicoscy]

On 30/05/2018 at 03:38, PeterWar said:

1- Optional flatteners

The scope is intended for visual use, would eyepieces like my 17mm Nikon NAV-SW benefit from using the TOA35-FL flattener? would the flattener vignette the 31mm Nagler?

2- Focuser:

Should I order it standard or with the feather touch focuser? I've heard that the feather touch would be preferred  when it comes to holding heavy eyepieces like my 31mm Nagler, but my understanding is that if I choose to go this route I won't be able to screw in the Takahashi TSA-120 flattener or the focal reducer if I ever decide to buy them, is that correct?

3- Mount and Tripod

I'm leaning towards using a DM-4 mount.

I would like a grab-an-go alt-az mount that doesn't look ugly and would be enough to carry the TSA-120 with heavy eyepieces or a binoviewer. I think I would prefer wood over metal, although I like the looks of the T-Pod tripod.

Any input you may have on this would be greatly appreciated.

 

Thank you very much for your time!

1 - Can't help much with that but field flatteners generally do not work well for visual. At 900mm focal length, field curvature should be a non-issue.

2 - I have the FS128 and I initially fitted the FTF micropinion assembly, then moved to the 3" FTF. Since you are concerned about accessories, keep the standard focuser and add the FTF micropinion. The Tak focuser can easily hold your Nagler 31mm. This allows you to enjoy the 10:1 reduction AND keep the original focuser so that you can attach Tak Accessories. 

Alternatively, if you do want a full FTF, you can specify Tak compatibility like I did. Mine is M72 at the eyepiece side, mated to Baader M72 to M68 adapter and mated to a 2" Clicklock.

3. The DM-4 can and will lift the TSA120 with aplomb. I spoke extensively with Tom Peters of Diskmounts as I considered mating this scope with this mount. Eventually I got the mount but got the FS-128 which works fine on the DM-4 but at its limits! I actually tested it but then mounted the scope on my AYO DIGI II mount. Funds permitting in the future, I will get the DM-6 as I love my DM-4!

I actually have the T-Pod (130mm). Nice sturdy mount. Equal lifting capacity to the Berlebach Planet, yet 4 kilos lighter and easier to set up. Yet I am the first to admit that wood has better dampening ability and a heavier tripod of equal capacity should perform better than a lighter one of the same capacity. 

For your scope get the T90 or T110, the DM-4 with the 8" extension and you should be fine. An observing chair is an integral part of any observing kit and I hope you have one. If not, this is the best of the lot I have tried from TS.

--------

Some more thoughts:

I was bouncing between the TSA120 and the FS-128. Being 100% visual I opted for something that cools down ever so slightly faster, has a bit more focal ratio which I like and a bit more aperture. If you want to see what I put myself through to decide, see here. I would have been equally happy with either scope.

A 5" class APO scope is a great all around instrument. Reasonable mounting requirements, reasonable focal length, reasonable resolution/aperture to keep one happy. The best all rounder in the refractors category IMHO. My 12" Dob could run circles around the FS-128, but there is something about the joy of using a decent sized refractor. I sold the 12" and have no regrets (plus I can buy it back any time!). It will keep you busy for a lifetime and based on views I got from 2" to 18" telescopes, I am super happy with my final choice of a scope. 

Others may beg to differ and I completely respect that. We all have our own preferences / perspective. This is mine and it feels right for me, maybe not for others.

[PeterWar]

On 05/06/2018 at 11:35, nicoscy said:

I actually have the T-Pod (130mm). Nice sturdy mount. Equal lifting capacity to the Berlebach Planet, yet 4 kilos lighter and easier to set up. Yet I am the first to admit that wood has better dampening ability and a heavier tripod of equal capacity should perform better than a lighter one of the same capacity. 

Nicos, I'm leaning towards buying the Berlebach Uni 18 tripod as I think the Planet would be a bit overkill, it has a load tollerance of 55kG which is way bigger than my planned load (about 14Kg tops).

 

Indeed FS-128 is a great scope!

[nicoscy]

Peter,  

The Uni 18 will do just fine for the TSA120! 

The Planet would be an overkill considering its weight and the T Pod just brings more weight capacity hence it is future-proof. 

Since you are building a complete system around a specific scope, the Uni is the best in terms of cost/weight/weight capacity considerations for the TSA120.

[dweller25]

Hello Petet,

I have a uni 18 and a uni 28

The uni 28 is perfect for my TSA102 and FS128

The uni 18 is too short for the refractors so I use it with my mak and sct

I have a full feathertouch focuser on the FS - it is superb, when funds allow I will put one on the TSA

If I were buying a TSA120 I would only consider the feathertouch option

 

 

[dweller25]

Posted twice by mistake

[nicoscy]

The 8” extension would be required for the TSA120 hence more height

[nicoscy]

Meant for the DM4 when mounting the scope

[Paz]

On 30/05/2018 at 12:47, iPeace said:

First, be aware that the "pillar" you see is composed of stacked elements. The top one is an integral part of the AZ8 head; the bottom two are these jobs:

I got one from TS in Germany, but it seems they no longer have them in stock. I got the other from Astromarket in Belgium:

https://www.astromarket.org/monteringen-en-toebehoren/az-monteringen/az8-alt---az-mount-with-tripod945835

Alternatively, I'm sure any reputable Losmandy dealer can source one for you.

 

How high is one segment and would these be compatible with a sky watcher tripod? I've got a sky watcher pillar extension I sometimes use with my eq5 but it's long and so its 'all or nothing" in effect. The option to increase height in smaller steps would be good.

[iPeace]

45 minutes ago, Paz said:

How high is one segment

6 inches.

46 minutes ago, Paz said:

would these be compatible with a sky watcher tripod

You'd need an adapter to connect it to the tripod and another adapter to connect the eq5 head; better off sourcing a shorter pillar that is compatible.

 

[Paz]

45 minutes ago, iPeace said:

6 inches.

You'd need an adapter to connect it to the tripod and another adapter to connect the eq5 head; better off sourcing a shorter pillar that is compatible.

Thanks for the information, the adapters issue is a shame!

[iPeace]

47 minutes ago, Paz said:

Thanks for the information, the adapters issue is a shame!

Well, yes - the thread size is nicely ubiquitous at 3/8" 16 TPI (standard photo tripod size), so that may have been a design consideration.

[ollypenrice]

I've never used a flattener for visual use with good Apos and I can't recall anyone doing so with visiting scopes. I don't have a 31 Nagler, my longest is the 26, but it's been fine in a number of refractors in this class.

I'd also be very surprised if the FT focuser were needed for visual observing. I agree that it doesn't sit too well with the Tak colour scheme! It is, though, an outstanding focuser. I have one on my TEC140. (A scope to consider, perhaps? The oil spaced triplet cools down pretty quickly.)

Olly

[PeterWar]

My TSA-120 in on its way and will arrive tomorrow!

I've spent a fun time doing  a lot of research and I'm about to finish this project. I know I want to mount my TSA-120 in a Berlebach (Uni 24 or Planet) tripod, but I'm undecided about which mount to choose.

Here's the short list of the final candidates:

 

1- Free-Turn X V2 Mount (don't know why unfortunately out of production, so not a choice apparently ).

 

2- Discmount Dm-6

 

3- Discmount Dm-4

 

4- Giro Ercole mount

 

5- Universal Astronomics UniStar - 7 lbs (also apparently out of production)

 

The Dm-4 ranks first in aestetics and lightweight (both very important factors), but performance on high magnification planetary viewing with the TSA-120 and the Mark V binoviewer concerns me...

[TakMan]

The FTX is sadly out of production as the designer/maker (Charles), passed away a short time ago. His son Jake is looking into the possibility of fulfilling the orders already on the books. So your only chance will now be the second hand market.

As an owner of Charles’ Nova Hitch mount, I can say that if you should see one come up for sale, I’d buy it in an instant !

Damian