Help focusing a Tak FC100DZ with a 2” Baader BBHS mirror diagonal

[IB20]

I find I have to pull all Televue eyepieces (that I’ve tried) out about 4-5mm to focus with the 76DCU with clicklock or standard Tak visual back and Tak prism. Same with the PST Coronado. Every other eyepiece is fine but both TV Delite and Plössl ranges required me to do it, so Don’s barrel extender suggestion on the eyepiece would probably be the easiest route.

Edited July 26, 2023 by IB20

[Louis D]

A bit off-topic, but what's up with Tak focusers?  I've never heard of AP, TEC, or, for that matter, most Chinese/Taiwanese made APO refractors having so many problems reaching focus with a range of eyepieces and diagonals.  Is it due to a lack of focuser draw tube travel range?  Is it because they were only intended for 1.25" diagonals?

I have heard of issues reaching focus with binoviewers in many refractors, but that's excusable since they require 100mm of additional in-focus travel.  My 90mm TS APO has two removable OTA sections to adjust its overall length for imaging vs. monoviewing vs. binoviewing.

[UKDiver]

30 minutes ago, Louis D said:

A bit off-topic, but what's up with Tak focusers?  I've never heard of AP, TEC, or, for that matter, most Chinese/Taiwanese made APO refractors having so many problems reaching focus with a range of eyepieces and diagonals.  Is it due to a lack of focuser draw tube travel range?  Is it because they were only intended for 1.25" diagonals?

I have heard of issues reaching focus with binoviewers in many refractors, but that's excusable since they require 100mm of additional in-focus travel.  My 90mm TS APO has two removable OTA sections to adjust its overall length for imaging vs. monoviewing vs. binoviewing.

I have the impression that Takahashi have designed a coherent system. If you wish to use something outside of that system, why should they take account of all the possible combinations?

I do use other kit on mine. My choice and I must bear the consequences with adapters and hassle.

[Nicola Fletcher]

47 minutes ago, UKDiver said:

I have the impression that Takahashi have designed a coherent system. If you wish to use something outside of that system, why should they take account of all the possible combinations?

I do use other kit on mine. My choice and I must bear the consequences with adapters and hassle.

I don't know if I am right, but I always think Taks are designed for straight through viewing first off, and they do provide instructions on how to use other setups via the system charts. 

If I were just to follow the system chart, I should use the part labelled 71S as they show on the chart - but it's not readily available and is more expensive than the other solutions. I'm going to try some of the clever solutions proposed by SGLers on here with FLO's advice also. Hopefully I will find a solution and I will post my findings here when I figure it out! 

Edited July 26, 2023 by Nicola Fletcher

[John]

34 minutes ago, Nicola Fletcher said:

I don't know if I am right, but I always think Taks are designed for straight through viewing first off, and they do provide instructions on how to use other setups via the system charts....

 

I understand that Japanese folk like observing straight through so that could well be the explanation.

I can think of a number of other brands that have "quirky" focuser arrangements. TAL, Skywatcher, Orion Optics to name a few.

Luckily we have forums such as SGL where solutions and experience can be easily and quickly shared 🙂

Edited July 26, 2023 by John

[Mr Spock]

A solution will always present itself. 
Though you do get the impression Taks are a throwback to the sixties. 

[Nicola Fletcher]

3 minutes ago, John said:

Luckily we have forums such as SGL where solutions and experience can be easily and quickly shared 🙂

Honestly, I am constantly amazed by how helpful and nice the SGL members are. My significant other couldn't believe how quickly people helped me with this!

[Hans Joakim]

In this (very nice) Japanese video, it is suggested that the short drawtube travel is to ensure rigidity of the focus and avoid bending of the drawtube when attaching heavy cameras: https://youtu.be/fv0ewiHee8U?t=540

The link starts the video at the relevant point, but the whole thing is a very nice to watch. There's also an excellent video on the 100DF: https://youtu.be/xl1V7Ii2bsU (now with both Japanese and English audio - very impressive!).

I found a 40 mm extension tube to be helpful for achieving focus when using the Baader 2" BBHS prism in my DF (top scope in photo, with M68 extension tube):

Edited July 26, 2023 by Hans Joakim

[Nicola Fletcher]

3 hours ago, Hans Joakim said:

In this (very nice) Japanese video, it is suggested that the short drawtube travel is to ensure rigidity of the focus and avoid bending of the drawtube when attaching heavy cameras: https://youtu.be/fv0ewiHee8U?t=540

The link starts the video at the relevant point, but the whole thing is a very nice to watch. There's also an excellent video on the 100DF: https://youtu.be/xl1V7Ii2bsU (now with both Japanese and English audio - very impressive!).

I found a 40 mm extension tube to be helpful for achieving focus when using the Baader 2" BBHS prism in my DF (top scope in photo, with M68 extension tube):

Thank you, and also thanks for the video links!

I’ve ordered the extension tube as @John suggested. FLO were concerned about raising up the EP with the parfocal rings so I’ll start with the extension and see how I get on. I’ll report back.

Thank you again for all your help 😊

[johnturley]

I suspect the problem is due to lack of travel on the focusing mounts, at one time most refractors had focusing mounts with around 5in (125 mm) of travel, some now however have only around 40 - 50mm (which I consider totally inadequate), and require the use of extension tubes with some eyepieces. As a bare minimum I consider that there should be at least 80mm of travel on the focuser.

John 

[F15Rules]

5 hours ago, UKDiver said:

I have the impression that Takahashi have designed a coherent system. If you wish to use something outside of that system, why should they take account of all the possible combinations?

I do use other kit on mine. My choice and I must bear the consequences with adapters and hassle.

I wonder if all Takahashi's own branded eyepieces all come to focus with their scopes? If not, that would be a bit naughty...

If they will, fair enough..most of us use a plethora of various brands and types, so it's not surprising if some of those don't come to perfect focus in a Tak focuser that almost certainly was designed only with Takahashi branded eyepieces in mind.

I confess that when I acquired my FS128, one of the first things I did was to replace the original back end focuser adapters.

This was initially as I wanted to use 2" eyepieces, and the original FS128 back end focuser was set up for 1.25" eyepieces only, and a genuine Tak 2" adapter for the Tak focuser was very expensive.

So it was Baader to the rescue, and I used a combination of their Tak specific adapters to allow me to bring all my 2" and 1.25" eyepieces to focus, and also to get native focus in binoviewers for most of my then 1.25" binoviewing eyepiece pairs.

Since then I have also switched to Baader 1.25" prism diagonals, which use up less of the optical path. 

Nicola, I hope you manage to sort out the focusing on your own Tak. Once you have, I know you will enjoy the superb views presented by your scope, knowing that the optics in your scope match or beat most other scopes commercially available today..😊

Dave

 

Edited July 26, 2023 by F15Rules
Text correction

[Nicola Fletcher]

Thanks Dave, I can’t wait to get it all sorted. I love the FC76DCU and have literally dreamt about the views through the 4 inch!

[MalcolmM]

51 minutes ago, F15Rules said:

I wonder if all Takahashi's own branded eyepieces all come to focus with their scopes? If not, that would be a bit naughty...

If they will, fair enough..most of us use a plethora of various brands and types, so it's not surprising if some of those don't come to perfect focus in a Tak focuser that almost certainly was designed only with Takahashi branded eyepieces in mind.

I confess that when I acquired my FS128, one of the first things I did was to replace the original back end focuser adapters.

This was initially as I wanted to use 2" eyepieces, and the original FS128 back end focuser was set up for 1.25" eyepieces only, and a genuine Tak 2" adapter for the Tak focuser was very expensive.

So it was Baader to the rescue, and I used a combination of their Tak specific adapters to allow me to bring all my 2" and 1.25" eyepieces to focus, and also to get native focus in binoviewers for most of my then 1.25" binoviewing eyepiece pairs.

Since then I have also switched to Baader 1.25" prism diagonals, which use up less of the optical path. 

Nicola, I hope you manage to sort out the focusing on your own Tak. Once you have, I know you will enjoy the superb views presented by your scope, knowing that the optics in your scope match or beat most other scopes commercially available today..😊

Dave

 

I have the DC variant and even though it has a very small focus range, I have never had any problems focusing, and I have quite a variety of eyepieces. Admittedly, I only use 1.25" eyepieces in the DC, so maybe I would run into problems with 2" eyepieces. I must give it a try sometime. Now Binoviewers ... that's a totally different ball game 🙂

Malcolm 

[John]

10 hours ago, Mr Spock said:

.....Though you do get the impression Taks are a throwback to the sixties. 

This video covers the first 10 years of Takahashi telescopes, so from 1967 to 1977.

It is interesting to see what features you can see on the early ones that are still used on the more recent models and it's not just the focusers !

Takahashi Telescopes The First Ten Years - YouTube

 

 

[Nicola Fletcher]

6 hours ago, John said:

It is interesting to see what features you can see on the early ones

Yes, it’s really interesting to see how they become more recognisable as Takahashis as time goes on.

These videos are great. I enjoyed the explanation of the design of Tak focusers - thanks also @Hans Joakim!

[HollyHound]

Bit late to this thread, but this is my setup for my DZ… also primarily using 1.25” eyepieces (XWs, ES 24 68deg and Nagler 3-6 Zoom).

Using the same 2” Baader diagonal as John, and all eyepieces come to focus around mid travel.

Good luck getting it all working… it’s a fantastic step up from the FC-76DCU 👍

[Nicola Fletcher]

49 minutes ago, HollyHound said:

Using the same 2” Baader diagonal as John, and all eyepieces come to focus around mid travel.

Thanks for replying @HollyHound - is that the clicklock with the M68 or the M72 thread do you know? Online, it looks like the M72 is best for use with diagonals and the M68 with binoviewers. I really like the idea of using the clicklock with the 2” diagonal.

The Stellalyra extender and a Tak part 14 arrived from FLO today so I’ll try to test them out this evening.

[John]

2 hours ago, HollyHound said:

Bit late to this thread, but this is my setup for my DZ… also primarily using 1.25” eyepieces (XWs, ES 24 68deg and Nagler 3-6 Zoom).

Using the same 2” Baader diagonal as John, and all eyepieces come to focus around mid travel.

Good luck getting it all working… it’s a fantastic step up from the FC-76DCU 👍

I used a similar arrangement for a while. The 2 inch click lock that I used was the 2 inch push fit version. 

There are many solutions that work - it can be a bit bewildering 😵

Currently I've gone back to 1.25 inch only with my Tak but I may dabble with a 2 inch compatible arrangement again at some point.

 

[Nicola Fletcher]

On 26/07/2023 at 11:11, IB20 said:

I find I have to pull all Televue eyepieces (that I’ve tried) out about 4-5mm to focus with the 76DCU with clicklock or standard Tak visual back and Tak prism. Same with the PST Coronado. Every other eyepiece is fine but both TV Delite and Plössl ranges required me to do it, so Don’s barrel extender suggestion on the eyepiece would probably be the easiest route.

I have found that the 3-6mm Nagler, 9mm Nagler and 24mm Panoptic work fine on the 76DCU with the Tak prism diagonal. My initial issue was using an Altair diagonal which didn’t allow me to reach focus. With these EPs anyway, the Tak diagonal is fine and I have no issue with the undercuts. I still don’t know if the 41 Panoptic will work for me (but I’m changing to the Baader 2” diagonal for this).

[Nicola Fletcher]

Problem solved 😊

I replaced part 14S supplied with the telescope with part 14 as @Franklin suggested so that the back is now the same as @JeremyS’s. With the Tak 1.25” prism diagonal, my EPs all come to focus. This is what it looks like:

 

For the 2” Baader mirror diagonal, I used the Stellalyra 35mm extender as suggested by @John and it worked like a charm. The 41mm Panoptic focused fine and I didn’t have to pull the eyepiece up out of the diagonal. 

Both of these options are much cheaper than buying the 71S part in the system chart - and I would have had a long wait to get one.

I only had enough time to test the setups before it clouded over but wow! Even just cruising around the south eastern sky with the Panoptic was incredible in less than ideal conditions. I can’t wait to get the DZ out as the nights get darker. 

I hope this will be useful for future owners of the FC100DZ and I can’t thank you all enough for your help!

[Goldypoker]

Hello all,

First time poster here! Hope I’m not too late for the party, especially when it relates to the OPs topic!🥂

I was hoping with the successful outcome of this thread for the OP, I might also find some solutions for my various issues.

I too have found myself overwhelmed by the proprietary Takahashi coupling system that makes usage of the FC100DZ with various non Takahashi products problematic…not to mention, even some combinations of TAK products without the correct adapters that are not included (and difficult to source, to say the very least😬) as part of the standard kit of accessories 

For myself, I would prefer a system of Baader clicklock accessories, and in anticipation of the scopes arrival I purchased a few odds and ends that are commonly recommended for the scope (especially wrt/a potential Baader visual train solution). I have also purchased a few TAK accessories, figuring that just in case I am unable to find solutions within my preferred Baader based optical train…I can at least find something that should work, if even for only 1.25 EPs. With this last point in mind, I purchased both the TAK 1.25 diagonal as well as the 4 slot EP turret. At the very least, the visual chart for the scope suggests that the turret will be able to provide sufficient focus travel/light path to bring *most* 1.25 EPs to focus using just the parts that came with the scope.

 

The non TAK accessories I have purchased are as follows;

2” Baader clicklock prism diagonal (w/1.25” adapter):

-this may have been a costly error, as most DZ systems I have seen “in the wild” appear to use the 2” T2 baader prism diagonal without the clicklock. Also, perhaps the 2” mirror clicklock would be more appropriate for usage with the scope in 2” mode, as opposed to the prism version? Either way, I hope there is a way to salvage this component, as I really prefer the clicklock system for (preferably) both 2” and 1.25” EPs. That being said, if there is simple (ie: using included components only) way to rectify the 2” clicklock version prism issue with a switch to a different version of the baader 2” prism, it might be more cost effective to go that route. Especially if the solution provides me enough latitude to bring most 2” and 1.25” EPs to focus using it🙏🏻
Certainly, I can always find a use for the 2” clicklock prism elsewhere (hmm, the 9.25 f/10 sct will thank me!)

Baader 2” clicklock clamps, both the M72 and the M64 versions:

-in case I want to attach the clamp directly to the focus tube, or just back of same. From what I’ve been able to research, the shorter light path of the M64 version is more conducive to bring binoviewers to focus with a broader range of Eps and lessor usage of supporting accessories (GPCs, barlow,PMs, etc). I am curious about dabbling in Binoviewing, as all reports I read from users seem uniformly positive…provided the optical train setup is workable and the collimation is good.

 

Baader m68 extension tube (20mm): maybe another mistake…heard it might help with some setups. Let’s hope so, it was one of few available ext tubes for the Baader system.

 

Anyways, given the two Tak components (1.25 diagonal/4 slot turret), the included accessories with the scope (listed in the DZ visual chart above in this thread), and the above noted components….I was hoping to finalize any additional components I may require to (hopefully) finalize the following setups:

 

BINOVIEWING: I am a complete newb in this regard, but have heard so many positive reports about the experience that to not do so with a superlative scope such as the DZ would be a astrological crime against humanity. That being said, I have no clue about which binoviewer and or supporting optical train would be best suited for the scopes abilities or the ease of accessibility to the various additional components required to pull it off. 
While I would appreciate any advice in this regard (Binoviewer choice/optical train advise, etc), it is really secondary to my main concern….being able to focus a wide arrange of EPs in both a 1.25” and 2” mode (and within the clicklock environment if possible).

 

1.25” VISUAL MODE: TAK turret *should* at least be able to take care of business with the included components until I can get the necessary couplings to make the tak 1.25” prism diagonal work. Even still, the clicklock 1.25 baader is also tempting. I assume it comes in a prism version as well? Any other suggestions would be most appreciated! As I am located in North America, I don’t have the same access to tkp00103 part 14 (non S type) that is found more easily in European markets. Any  additional solutions and/or suggestions by which to get the TAK 1.25 prism to the correct light path for optimal visual usage with 1.25” EPs?

If I can’t get any workable solution beyond what I (* think I*) have now, I will probably begin with the TAK turret and the recommended optical train listed in the system chart for visual (no additional components required). I was hoping to use my 18.2, 5, 4 and 3 mm Delites…although based on some previous comments here some Delites seem to be problematic for this config? Any thoughts/advice?

 

2” VISUAL MODE: As related above, any combo of diagonals (prism or mirror) that will ensure getting to focus with the majority of commonly used 2” EPs (and preferably, 1.25s with adapter). If I can do it with the equipment I already have…great! If not, what advise would you offer to get me there given what I can readily access.

EP SELECTION: I tend to lean heavily on the TV side of EPs…..Ethos and Delos for mid range mags (14-10mm), Delites for high mag (3-5mm) and both the 41 panoptic/18.2 Delite for low to med low mag range. I also have the Baader (with barlow) and APM zooms, and a few pentax XWs for when I’m manually tracking.

Any suggestions wrt/EPs that will enhance the DZ experience in any of the above modes?

Sorry for the overly long post, but it’s quite painful see this beauty just sitting here and barely being able to tap it’s potential because of the difficulty in acquiring the necessary parts. I have seen many potentially workable solutions depicted here in this post, but unfortunately they do not list the specific components of the optical train and I am unable to piece it together from the pictures.  I am hoping the collective goodwill of the SGL network will provide me assistance in my optical uncertainty😢

 

Any comments/advice/insights would be appreciated!

 

 

 

 

 

 

 

 

Edited August 2, 2023 by Goldypoker
Clarification

[Manoj77]

On 25/07/2023 at 14:24, John said:

I use a Baader T2 Zeiss prism diagonal with 1.25 inch fittings front and back. That goes straight into the 2 inch fitting on the end of the drawtube without the 71L extension. All my 1.25 inch eyepieces reach focus somewhere around the central part of the drawtube travel with that arrangement (pic below).

 

Hi, How does your Baader T2 Zeiss diagonal attach to your FC-100DF?  Did you attach the Baader 2" nosepiece to the T2 ?

[John]

17 hours ago, Manoj77 said:

Hi, How does your Baader T2 Zeiss diagonal attach to your FC-100DF?  Did you attach the Baader 2" nosepiece to the T2 ?

I use either a T2 - 1.25 inch nosepiece or a T2 - 2 inch one. Not Baader but similar.

My scope is a FC100-DL but I think the focuser is the same as the DF.