2" BBHS Prism Diagonal - Barrel Removal

[globular]

Hi All,
I'm looking for some help with my Baader 2" Prism Diagonal (#2456117).
It looks like this:

And from Baader's website I know it can look like this:

But for the life of me I can't unscrew the barrel.
Is there a 'trick' to getting it off?
A hidden locking grub screw somewhere perhaps?
Or do I just need to be braver and really go for it?

Thanks in advance 

 

[jetstream]

1 hour ago, globular said:

Hi All,
I'm looking for some help with my Baader 2" Prism Diagonal (#2456117).
It looks like this:

And from Baader's website I know it can look like this:

But for the life of me I can't unscrew the barrel.
Is there a 'trick' to getting it off?
A hidden locking grub screw somewhere perhaps?
Or do I just need to be braver and really go for it?

Thanks in advance 

 

I took mine off and replaced it, it took a bit of doing but it came off- not that I'm recommending use of force. Mine is about 6 -7 yrs old.

[globular]

Thanks @jetstream….So it just unscrews….I’m not going to break some hidden fastening….?

I’ll give it some welly tomorrow then.

[jetstream]

22 minutes ago, globular said:

Thanks @jetstream….So it just unscrews….I’m not going to break some hidden fastening….?

I’ll give it some welly tomorrow then.

Mine just unscrews-but these fine threads can lock up. Placing the palm of the hand over the adapter and pushing while turning can help. Mine is a Baader/Zeiss 2" prism diag with no markings on the body, no idea if yours is exactly the same. I'll go get it tomorrow from the sea can and compare.

[jetstream]

https://agenaastro.com/baader-2-90-star-diagonal-zeiss-prism-2406010.html

Pretty sure this is mine

"On the eyepiece side, the 2" eyepiece holder can be unscrewed. This will expose an inverter ring with an SCT male thread (2" x 24TPI). Removal of this inverter ring then exposes an SCT female thread on the diagonal body. On the telescope side, the nosepiece can also be unscrewed, exposing SCT female threads on the housing. Hence, this diagonal can be closely coupled with an SCT telescope (using the optional SCT lockring) to provide the shortest physical connection for fork-mounted telescopes with limited base clearance. It can also be used with a variety of other Baader T-2 system components (sold separately) for various adaptations."

Edited September 13, 2021 by jetstream

[jetstream]

You got a Baader SCT lockring? part # 2458270, pretty sure this is what YKSE used.

[globular]

Sounds like yours has the same connections as mine, but is a slightly different model.
Baader have lots of similar looking stuff but they all have different # numbers.

The barrels on my other diagonals screws on and off easily enough.. just nice and stiff… nothing too tight.

I’ve had filters (M48 thread) that sometimes seem to jam… but a change of temperature or a light tap tends to free them…. it’s important to try and apply even pressure around the barrel so as not to distort it as you twist.

But the barrel on this diagonal (2” SC thread) feels so firm, and is not responding to my usual persuasion, that it feels like it’s glued or fixed with a screw somewhere.  I know it shouldn’t be… because this particular model has all sorts of connection options on baader’s website… but I wanted to check with the knowledge bank here at SGL before I attempted anything that may break this rather expensive item.

Edited September 13, 2021 by globular

[globular]

53 minutes ago, jetstream said:

You got a Baader SCT lockring? part # 2458270, pretty sure this is what YKSE used.

I didn’t go that route because I don’t want to have to screw on and off different configurations.

Instead I’ve gone for a custom visual back that has a 2” nosepiece clamp (with compression ring and 3x 120 degree offset thumb screws for solid centered clamping) but with only a 21mm light path.
This means I need to replace the current 27mm barrel on this diagonal with a 21mm one.
Hence needing the old one off.

I can then easily switch between my 2” diagonal for cyclops viewing or T2 diagonal + binoviewers… all while keeping the light path as close as possible to the optional one for the telescope. (bang on (F10.5) for cyclops and only a little worse than YKSE for binoviewing… but with more convienience.  YKSE got F10.9 with his binoviewers and lock ring and I’ll get F11.0 (without GPC) …. if they ever arrive)

Edited September 13, 2021 by globular

[jetstream]

52 minutes ago, globular said:

is not responding to my usual persuasion,

good luck and let us know if you will, as always I'll put the result in the memory bank.

[globular]

Just for completeness, I got it off 

All I needed to add was just a small amount of..... confidence.

I now have a shorter barrel added which is still gripped nice and firmly and squarely by my ultrashort clamp... but with a shorter overall light path.  Sorted.

[jetstream]

50 minutes ago, globular said:

Just for completeness, I got it off 

All I needed to add was just a small amount of..... confidence.

I now have a shorter barrel added which is still gripped nice and firmly and squarely by my ultrashort clamp... but with a shorter overall light path.  Sorted.

Perfect, I checked mine and it was the mentioned unit but I had put the stock chrome nosepiece back on. Just to see, I unscrewed it then screwed it back on however not as tight as original. These diagonals sure do work thats for sure.

 

Edited September 15, 2021 by jetstream