Collimated for life?

[Trollinthewall]

Just a quick one, I'm on the verge of ordering my first scope a Skywatcher start discovery 150p, I've just read that there is no way to collimate the scope and its considered "collimated for life" by the manufacturers. Would this become a problem not being able to collimate it at all? 

https://www.firstlightoptics.com/az-goto/sky-watcher-star-discovery-150p.html

[Moonshane]

It would become a problem if the mirrors went out of alignment but not if they don't.  I'd not buy a newt that I could not collimate 

[newbie alert]

Is that what they call a bird Jones design..with like a Barlow installed?

[laudropb]

No it's not a bird Jones. I know someone who has star discovery and he is very pleased with it, but I have to agree with Shane I would be very uneasy with a newt I could not collimate.

[Trollinthewall]

1 hour ago, newbie alert said:

Is that what they call a bird Jones design..with like a Barlow installed?

Forgive my ignorance, but what's a bird jones design? 

[John]

30 minutes ago, Trollinthewall said:

Forgive my ignorance, but what's a bird jones design? 

The optical design is shown below. The benefit is that you can have a long focal length in a short tube. The design is often found in low price scopes though and not well executed so the performance is generally mediocre and the collimation of the mirrors awkward because devices such as laser collimators don't work with it.

 

[Peter Drew]

5 hours ago, Trollinthewall said:

Just a quick one, I'm on the verge of ordering my first scope a Skywatcher start discovery 150p, I've just read that there is no way to collimate the scope and its considered "collimated for life" by the manufacturers. Would this become a problem not being able to collimate it at all? 

https://www.firstlightoptics.com/az-goto/sky-watcher-star-discovery-150p.html

I've just had a look at the specification and a read through the manual and can find no reference to the optics being not possible to collimate. ?? 

[Trollinthewall]

13 minutes ago, Peter Drew said:

I've just had a look at the specification and a read through the manual and can find no reference to the optics being not possible to collimate. ?? 

Thanks for explaining that John, looks almost like a Barlow built into the eyepiece? 

 

And oh really Peter? I've not seen the manual was going by a video review of it I saw and the astronomer said there was no way to collimate, however if the manual don't state this then I guess there is a way to collimate it was just the one drawback to me if it weren't, as it looks a fantastic scope for the price, thanks for that

[Ricochet]

1 hour ago, Peter Drew said:

I've just had a look at the specification and a read through the manual and can find no reference to the optics being not possible to collimate. ?? 

From what I remember of previous posts the Star discovery 150p and Heritage 100p both have fixed plastic mirror cells to which the primary mirrors are fixed. With a fixed cell there are no collimation screws and so collimation is done at the factory by adjusting the angle at which the mirror cell is fixed to the main tube. I think that the screws holding the cell to the tube are also glued to prevent the cell shifting in relation to the tube.

A quick search brings up the following:

Quote

upon the purchase of

a laser collimator i found the scope to be miles out of kilter, a SkyWatcher mistake as the mirror in the SD is technically non collimatable and stuck in for good measure.

I released the glue and managed to collimate it with ease even though a little unorthodox as the mirror holder is held in with 4 screws around the tubes outer edge.

However, it seems the secondary is adjustable and was also out of position so it may have just been that the secondary had moved for the above user and the primary could have been left.

[John]

1 hour ago, Trollinthewall said:

Thanks for explaining that John, looks almost like a Barlow built into the eyepiece? ......

 

It's supposed to be both a barlow / focal extender and a corrector to sort out the issues that a fast spherical primary creates. Takahashi and Vixen can pull this sort of thing off. Low cost producers do the best they can but ultimately there are quite a few compromises left in the optical system.

[Dave In Vermont]

I'd be most interested in reading as many reviews of this scope by actual end-users. It's possible we could need to amend the exclusive 'Takahashi & Vixen' club.

And I'd like to hear SkyWatcher explain why, exactly, they chose to go with the design they did.

Dave

[Peter Drew]

I have a SW Heritage 114 Virtuoso, this too appears to have no conventional primary mirror adjustment facility. On this one however, the cell is not bonded to the tube so releasing the attachment screws allows the cell to be tilted for collimation. Just as well as the collimation was slightly off which would have taken the edge off its otherwise excellent performance. I can understand the rationale for offering a pre-collimated, non optically adjustable telescope at entry level but it does the buyer or the manufacturer no favours if this is not accurate. I really rate the virtuoso, it is more stable than others I've tried and the drives are very nice, the BIG plus is that it can be moved in both ALT and DEC manually with or without the motors running. Well worth the extra cost if a compact telescope is needed and alternative OTA's can be substituted. I have also tried a 130 Prodigy and was impressed by its operation and the quality of the optics. 

[happy-kat]

I think it is too strong to say they can't be collimated because the secondary mirror can be adjusted should collimation be required. There are several members on SGL using the star discovery. The best thing the mount has freedom find which is a great feature and also shared with the small virtuoso mount.

I have a Virtuoso mount and rate it, I power mine from the lightweight Celestron LiPo4 battery 12v.

[andrew s]

While I know nothing about this model of telescope I have built, bought and used a number of Newts over the years. I never had any issue with my Newts going out of collimation despite considerable abuse e.g drilling 3/4" hole in the steel frame.  However, I followed Victorian engineering principles and over designed the mirror supports and adjustments. 

I came to the conclusion that ability to collimate commercial Newtswas in fact the cause of them needing regular collimation  as the adjustments were poorly designed and under engineered.

Regards Andrew

[Peter Drew]

4 hours ago, andrew s said:

While I know nothing about this model of telescope I have built, bought and used a number of Newts over the years. I never had any issue with my Newts going out of collimation despite considerable abuse e.g drilling 3/4" hole in the steel frame.  However, I followed Victorian engineering principles and over designed the mirror supports and adjustments. 

I came to the conclusion that ability to collimate commercial Newtswas in fact the cause of them needing regular collimation  as the adjustments were poorly designed and under engineered.

Regards Andrew

Couldn't agree more.