Micro Focuser for Takahashi 100 DZ

[MalcolmM]

6 hours ago, John said:

As I understand it, steeper light cones (faster scopes) have a narrower zone of apparent sharp focus than slower scopes do

This is my understanding too and is noticeable when turning the f5.9 FS60CB into the f10 FS60Q with the CQ x1.7 extender.

Malcolm 

[MalcolmM]

25 minutes ago, johnturley said:

Do you think that there is much difference in quality between the T2 Zeiss prism diagonal, and the non- Zeiss version apart from the different size. As mentioned, I was thinking of getting the latter with a built in 1.25in helical focuser, as an alternative to fitting a MEF3 Micro Edge Focuser. 

Note: I do have a Baader 2in Dielectric Diagonal I can use for low power wide field views, where focusing is not so critical.#

John 

I have both Baader diagonals and can honestly say I have not noticed any difference visually, though I've not done detailed comparisons. The Zeiss does have a slightly longer lightpath which can pose problems with Binoviewers, but it has not caused me trouble yet.

I've also got the Baader helical focuser and would choose the MEF3 over it every time! I find the MEF3 much much easier to use. I never attach the Helical focuser these days.

Malcolm 

[John]

51 minutes ago, johnturley said:

Do you think that there is much difference in quality between the T2 Zeiss prism diagonal, and the non- Zeiss version apart from the different size. As mentioned, I was thinking of getting the latter with a built in 1.25in helical focuser, as an alternative to fitting a MEF3 Micro Edge Focuser.... 

 

I have not compared them myself. I have read that a few folks have noticed slightly less light scatter with the Zeiss version but only on the nights of best seeing and when observing certain targets. Most reports are that they perform the same.

When I'm using 2 inch eyepieces with my FC100-DL (which is infrequently) I use an AP Maxbright 2 inch diagonal or a TV Everbright 2 inch. 

 

Edited November 28, 2023 by John

[Stu]

2 hours ago, johnturley said:

Am I right in thinking that this has a better quality prism , and will be more comparable with the Tak Prism Diagonal quality wise, although of course the latter only has a 1.25 prism.

My view would be you’ve got a top notch scope, so remove any doubt about limiting factors and get the Zeiss T2. I’ve not compared with a standard version either but it just means I know there’s no issue with my diagonal.

[Franklin]

59 minutes ago, johnturley said:

I was thinking of getting the latter with a built in 1.25in helical focuser, as an alternative to fitting a MEF3 Micro Edge Focuser.

I've had the 32mm T2 Baader prism with fine focus for a while and it's my most used diagonal and easily the best I've owned. Being T2 on both sides you can swap between 1.25" and 2" nosepieces and even fit a T2 clicllock 1.25" on the eyepiece end. I've never used the top-end Zeiss diagonals from Baader but they must be exceptional to be better than the 32mm version.

[johnturley]

15 minutes ago, Stu said:

My view would be you’ve got a top notch scope, so remove any doubt about limiting factors and get the Zeiss T2. I’ve not compared with a standard version either but it just means I know there’s no issue with my diagonal.

Noted, although the cost of the T2 Zeiss Prism (£198), plus 2in Nosepiece (£30) and 1.25in to T2 Helical focuser (£40) would come to a total of £268, more than the £247 for the MEP3 Micro Edge Focuser.

John 

[JeremyS]

33 minutes ago, Stu said:

My view would be you’ve got a top notch scope, so remove any doubt about limiting factors and get the Zeiss T2. I’ve not compared with a standard version either but it just means I know there’s no issue with my diagonal.

My philosophy too, Stu.

I use Baader mirror diagonals rather than prism. I went with BBHS, tho. I can’t see a difference compared to the standard Baader mirror.

Having said that, I’m currently running with the Tak 2-inch mirror diagonal on my FC 100DZ. I often use the Tak 1.25-inch prism, also without detriment.

Edited November 28, 2023 by JeremyS

[MalcolmM]

27 minutes ago, JeremyS said:

My philosophy too, Stu.

Mine too!

Malcolm 

[mikeDnight]

3 hours ago, johnturley said:

Agree, presumably you also need to get a T2 to 2in eyepiece holder, and that this doesn't cause any vignetting with the 30mm UFF (which I also have), and which I think has a field stop of about 36mm. 

P.S. Just been looking on FLO's website again, and noticed that there are actually two different T2 Diagonals, one type, including the version with the built in helical focuser, has just a 1.25in prism, the other (which I assume is what you have on order) has a larger (I assume about 42mm prism), but you have to buy the nosepiece and eyepiece holder separate. 

Baader T-2 Prism Star-Diagonal | First Light Optics

This latter version  Baader T-2/90° diagonal features a prism manufactured to Zeiss specification from BaK4 glass, multi-coated, inside a solid metal case, and I assume can be used without vignetting with the 32mm UFF. Am I right in thinking that this has a better quality prism , and will be more comparable with the Tak Prism Diagonal quality wise, although of course the latter only has a 1.25 prism.

John 

As well as being able to change the helical focuser for a 2" click lock, the BBHS prism allows the direct connection of the Maxbright ll binoviewer for low power viewing.

30mm Ultra Flat with 2" clicklock. I bought the 2" nose piece for this.

The Baader Zeiss BBHS prism with Maxbright II directly attached.

 

[mikeDnight]

3 hours ago, johnturley said:

Agree, presumably you also need to get a T2 to 2in eyepiece holder, and that this doesn't cause any vignetting with the 30mm UFF (which I also have), and which I think has a field stop of about 36mm. 

P.S. Just been looking on FLO's website again, and noticed that there are actually two different T2 Diagonals, one type, including the version with the built in helical focuser, has just a 1.25in prism, the other (which I assume is what you have on order) has a larger (I assume about 42mm prism), but you have to buy the nosepiece and eyepiece holder separate. 

Baader T-2 Prism Star-Diagonal | First Light Optics

This latter version  Baader T-2/90° diagonal features a prism manufactured to Zeiss specification from BaK4 glass, multi-coated, inside a solid metal case, and I assume can be used without vignetting with the 32mm UFF. Am I right in thinking that this has a better quality prism , and will be more comparable with the Tak Prism Diagonal quality wise, although of course the latter only has a 1.25 prism.

John 

As well as being able to change the helical focuser for a 2" click lock, the BBHS prism allows the direct connection of the Maxbright ll binoviewer for low power viewing.

30mm Ultra Flat with 2" clicklock. I bought the 2" nose piece for this.

The Baader Zeiss BBHS prism with Maxbright II directly attached.

 

[Telescope40]

Hello. Great discussion. Here’s my take. Got a MEF focuser fitted to my Tak FS128. Like it a lot. 
However if binoviewers in use I have got an option for finer control. Maybe not what the OP may be looking at 

Regards John