SharpStar 94EDPH?

[kbrown]

Hi,

I'm seriously considering purchasing a SharpStar 94EDPH. A couple of questions that I haven't been able to find answers to still remain though:

1. What is the maximum payload on the focuser? Or how much does your imaging combo weigh and have you had any problems with it?

2. Are the lens cell and/or focuser adjustable or fixed i.e. is it possible to collimate the scope to any degree?

3. Did you feel it needed collimation out of the box?

4. Any reason why not to buy this scope?

 

Thanks,

Kari

[fozzybear]

Kari

I'm sure @tooth_dr has one of these maybe he can answer your questions

Andy

[johninderby]

Discussed in this thread

 

[tooth_dr]

2 hours ago, fozzybear said:

Kari

I'm sure @tooth_dr has one of these maybe he can answer your questions

Andy

Cheers Andy, I did have one but ended up returning it.

 

2 hours ago, kbrown said:

1. What is the maximum payload on the focuser? Or how much does your imaging combo weigh and have you had any problems with it?

2. Are the lens cell and/or focuser adjustable or fixed i.e. is it possible to collimate the scope to any degree?

3. Did you feel it needed collimation out of the box?

4. Any reason why not to buy this scope?

1. It couldnt hold a camera/EFW combo without sliding out c.1.8kg.  When I adjusted the focuser to increase tension the knob became spongy and difficult to use - you had to turn it past where you wanted to end up and it sprang back a bit!  There seems to be a no middle ground.  I havent used a rack and pinion focuser before, but this felt very hard to use.  It worked ok when I added a motor focuser.

2. I nont know - I bought a refractor so that I would hopefully never have to collimate it.

3. I think the collimation was good, and any distortion to the stars was symmetrical.  The dedicated flattener couldnt deliver small stars across the field, and introduced astigmatism and chromatic aberration.

4. The FWHM was high even when accurately focused.  In retrospect if I look at the spot diagrams, i think the scale is large (100um per square versus 20um for competitors) so to be expected.  If you count up the cost of the scope, a flattener, the correct adapter to connect flattener to focuser, and then a motor focuser, you are certainly well over £1600.   I dont know if this is a good investment?

 

[kbrown]

38 minutes ago, tooth_dr said:

1. It couldnt hold a camera/EFW combo without sliding out c.1.8kg.  When I adjusted the focuser to increase tension the knob became spongy and difficult to use - you had to turn it past where you wanted to end up and it sprang back a bit!  There seems to be a no middle ground.  I havent used a rack and pinion focuser before, but this felt very hard to use.  It worked ok when I added a motor focuser.

I haven't used rack and pinion focuser before either. I was going to add a motor focuser anyway. Most likey a DIY one as I've done before on my newt. So I guess you left the tension knob rather loose when you added the motor focuser and relied it to hold the position more than anything else?

41 minutes ago, tooth_dr said:

3. I think the collimation was good, and any distortion to the stars was symmetrical.  The dedicated flattener couldnt deliver small stars across the field, and introduced astigmatism and chromatic aberration.

That is a bit surprising to hear. I initially wasn't going to get the dedicated flattener as I already have a HoTech SCA Field Flattener that should work with this in theory.

43 minutes ago, tooth_dr said:

4. The FWHM was high even when accurately focused.  In retrospect if I look at the spot diagrams, i think the scale is large (100um per square versus 20um for competitors) so to be expected.

Hmm... Certainly food for thought. Thank you! I will have a closer look now!

 

Cheers,

K