Sharpstar 94

[tooth_dr]

Came across this as a replacement for my ED80. Anyone used it?

https://www.firstlightoptics.com/sharpstar-telescopes/sharpstar-94edph-f5-5-triplet-ed-apo-telescope.html

[johninderby]

Came across this on CN. Some useful info.

https://www.cloudynights.com/topic/737100-sharpstar-94mm-f55-ed-triplet-apo-first-impressions/

Edited December 13, 2020 by johninderby

[tooth_dr]

37 minutes ago, johninderby said:

Came across this on CN. Some useful info.

https://www.cloudynights.com/topic/737100-sharpstar-94mm-f55-ed-triplet-apo-first-impressions/

Thanks John, did read that, was wondering if anyone on here has taken the plunge.

[Miguel1983]

i have the 76 version from TS, i took a look at the CN-post and i conclude just as with the 76 the 94 shows some elongated stars in the corners when backfocus is 55-56mm as suggested.

Last week i've added another mm spacer but the weather has been so poor  that testing has yet to begin.

To clarify, my image train is : reducer with Astronomik L3 inside - 1mm spacer - ZWO OAG - 1mm spacer - 11 mm spacer - ZWO EFW (Optolong 1,25" filters) - 294MM.

Other than that i think its a good scope, but it clearly needs exact backfocus.

The tube ring/clamp and dovetail on the 76 however are useless, i could not balance, the 94 has a longer tube so might be OK.

 

[tooth_dr]

Thanks for that Miguel.  It’s looking like a really nice scope for me, at a reduced FL it’s fast enough at F4.4 and gives a good FOV. Decisions decisions. 
 

[DaveS]

Looks like This one from TS, or With the reducer

[tooth_dr]

47 minutes ago, DaveS said:

Looks like This one from TS, or With the reducer

Thanks Dave. Have you used the TS version?

[DaveS]

Alas no, but I have been sorely tempted. Mostly held back by me reluctance to spend any serious money on kit until I have my pensions coming in.

The 80mm f/4.4 in my sig is a real devil to get the spacing right, finicky down to the tenth of a mm.

[tooth_dr]

17 minutes ago, DaveS said:

The 80mm f/4.4 in my sig is a real devil to get the spacing right, finicky down to the tenth of a mm.

At least collimation isn’t an issue (hopefully), spacing i can handle 👍🏻

[tooth_dr]

That's FLO stock down to 1 🙀

[tooth_dr]

I went ahead and ordered a Sharpstar 94, and it arrived just before Xmas.  I also ordered the 0.8x reducer, which arrived on the 23rd.

The weather hasnt been great but I did manage an outing.  I swapped the supplied vixen dovetail for a losmandy one.

I've attached a single 300s sub of HH with the Atik 383L+ and Ha filter (no flats just BPM with reducer 413mm F4.4) and a stacked image of the moon with the 290MM (without the reducer 517mm F5.5), both below.

Does anyone know which screw to adjust to tighten the focuser?  It's slipping out under the load of my camera and EFW (1.8kg).  Plus the fine control is very spongy.  I've searched for a guide but cannot find one.

 

Cheers!

Adam

 

Edited January 1, 2021 by tooth_dr

[Miguel1983]

Congrats with the new scope !

Looks like your backfocus is pretty-much spot on, i had to replace the second 1mm spacer, as mentioned earlier, and replaced it with 0,5mm, seems better.

Stil got some tilt though.

Your image train is different though so not really a reference.

I haven't worked on the focuser on mine, but there must be some screws to adjust tension i suppose, i'll take a look when i'm in the obs.

[Nikolas74]

I have this scope on my mind... I like the specs!!! 

Edited January 1, 2021 by Nikolas74

[tooth_dr]

I wanted to share this video of the focusing knob.  I haven’t adjusted anything so far, it was like this out of the box, and is struggling with a ccd/EFW set up.

 

 

 

[tooth_dr]

I received my SharpStar 2.5" field flattener today, and plotted the figures on a graph, to see what backspacing I should start off trying with my 517mm focal length scope.  The last plot point was hard to know where to plot.  I went with 500 and then 450mm.  Does it look about right to aim for somewhere about 103mm as a starting point?

Edited January 30, 2021 by tooth_dr

[david_taurus83]

Id start at 106mm and work in at 1mm increments. Its much better than having to go back and forth.

[david_taurus83]

Also, just looked at the video for the focuser. My WO focuser and Altair (same focusers) do that with a load on it. Its just the backlash in the gear mesh being taken up after you rack in and not really an issue when using the DSD AF though the critical focus zone at f4.4 will be much narrower.

[tooth_dr]

The new 2.5” field flattener doesnt fit the focuser 🤷‍♂️  👎🏻👎🏻

 

[david_taurus83]

7 minutes ago, tooth_dr said:

The new 2.5” field flattener doesnt fit the focuser 🤷‍♂️  👎🏻👎🏻

 

Eh?! Its for that scope?

[newbie alert]

On 01/01/2021 at 10:33, Miguel1983 said:

Congrats with the new scope !

Looks like your backfocus is pretty-much spot on, i had to replace the second 1mm spacer, as mentioned earlier, and replaced it with 0,5mm, seems better.

Stil got some tilt though.

 

You're not using delrin spacers by any chance are you? As they're not the same thickness all the way around.. baader aluminium ones are far better

 

[tooth_dr]

8 minutes ago, david_taurus83 said:

Eh?! Its for that scope?

Well I thought so, it does certainly suggest that in the telescope text.  Looks like it’s M68 and the scope focuser is M74.  Unless I’m missing something or haven’t attached adapters correctly  

https://www.firstlightoptics.com/sharpstar/sharpstar-94edph-f5-5-triplet-ed-apo-telescope.html

 

[david_taurus83]

6 minutes ago, tooth_dr said:

Well I thought so, it does certainly suggest that in the telescope text.  Looks like it’s M68 and the scope focuser is M74.  Unless I’m missing something or haven’t attached adapters correctly  

https://www.firstlightoptics.com/sharpstar/sharpstar-94edph-f5-5-triplet-ed-apo-telescope.html

 

That is a bit odd. I'm used to using M68 to M63 adapters for mounting flatteners to 2.5" drawtubes but there doesn't appear to be an advert for an M74 to M68 adapter?

[DaveS]

You will need one of These.

I have the same flattener (Under the TS label) on my 130 f/7 apo, and find the awkwardness is with that dratted M69 female camera side thread.

[DaveS]

This is the equivalent TS flattener. There are recommended adaptors further down the page.

[tooth_dr]

48 minutes ago, DaveS said:

You will need one of These.

I have the same flattener (Under the TS label) on my 130 f/7 apo, and find the awkwardness is with that dratted M69 female camera side thread.

Thanks Dave.

This is frustrating as FLO knew I was buying this for the 94 telescope but didn’t mention an adapter.  This means another £50-60.  It is starting to look like an esprit 100 would have been a better choice.