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Sharpstar Z4 Feedback

Sharpstar Z4 Askar FRA500 Refractors Buying Advice
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AstroGinger avatar
AstroGinger avatar
There are not that many people on astrobin using the Z4 and not that many feedback as well, here or elsewhere.
On the paper I find this telescope very interesting and by judging the photos, you can't be ashame of the results.
I will be interested to have your opinion on using this telescope even compared to the more popular FRA 500.
The strength and the weakness !
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
No personal experience from my end, but an acquaintance recently returned his due to issues with what the vendor claimed to be pinched optics. The spot diagrams show some coma is to be expected perhaps, but I agree, there aren't that many reviews of it, neither are there that many images and each I've seen show some degree of coma. Except for the ones that has had fake spikes added to them, something even Sharpstar have done on their own website. People should do whatever they feel like, but when a vendor does this on their product page it kinda feels like they are hiding something.

Either way, if you live ina climate where you get cold temps you should perhaps be wary that it can suffer from pinched optics. Something I've never seen with my Sky-Watcher telescopes even down to -25 degrees at least.
donsinger avatar
donsinger avatar
Mine suffered from pinched optics and I returned it. Replaced the Z4 with an FRA500 which I have not been able to test because of bad weather
padiac avatar
padiac avatar
Just out of curiosity,  what is pinched optics?
Johannes Maximilian Möslein avatar
Johannes Maximilian Möslein avatar
No personal experience from my end, but an acquaintance recently returned his due to issues with what the vendor claimed to be pinched optics. The spot diagrams show some coma is to be expected perhaps, but I agree, there aren't that many reviews of it, neither are there that many images and each I've seen show some degree of coma. Except for the ones that has had fake spikes added to them, something even Sharpstar have done on their own website. People should do whatever they feel like, but when a vendor does this on their product page it kinda feels like they are hiding something.

Either way, if you live ina climate where you get cold temps you should perhaps be wary that it can suffer from pinched optics. Something I've never seen with my Sky-Watcher telescopes even down to -25 degrees at least.

I almost didn't believe the thing with the fake spikes, but damn...that's really ridiculous. And that scope isn't that cheap at almost 3k €. They didn't even try to make it subtle.
Well, now I know which brand to avoid in the future. 

https://www.sharpstar-optics.com/Products_1/26.html
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
Just out of curiosity,  what is pinched optics?

The fourth comment here explains it pretty well: https://www.cloudynights.com/topic/697015-what-is-a-pinched-optic/
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
I almost didn't believe the thing with the fake spikes, but damn...that's really ridiculous. And that scope isn't that cheap at almost 3k €. They didn't even try to make it subtle.
Well, now I know which brand to avoid in the future. 

https://www.sharpstar-optics.com/Products_1/26.html


I know, I only discovered it when someone kept asking why, as a refractor, it had spikes and decided to do some minor research on the matter. I did consider the Z4 myself, but I'm glad I went with the tried and tested Esprit series in stead. Got it a lot cheaper at the time as well.
Leah Deckard Hallett avatar
Leah Deckard Hallett avatar
I have this scope and yes corner stars have some coma with an aps-c size sensor. I think with a four thirds size sensor you wouldn’t see much coma at all. I find it to be a sharp scope and fast-gathers light quickly.  

If you use version 4 of BlurXterminator by Russell Croman it works to fix coma - so much so it’s a non issue even on aps-c.
Helpful Concise Supportive
AstroGinger avatar
AstroGinger avatar
Thanks all for your comments.
I was secretly thinking that, like my old Tak TSC 225, the Z4 optic was hand-made and that only a few were produced because of the high manufacturing cost…
But it seems I was wrong.
I wouldn't blame Sharpstar/Askar, they can come out with beautiful telescopes and optics at reasonnable price, as for me, I'm super happy with my ACL 200!
And in terms of design, the Z4 is a real success.
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Nick Grundy avatar
Nick Grundy avatar
I actually like my Z4 quite a bit, but I do think it's hit and miss. I still think the focuser should be better, but overall I like the design and fit of it all. 

I'd certainly be tempted by an FSQ-85 with the new reducer, but that's at least 2x the price.
Jan Erik Vallestad avatar
Jan Erik Vallestad avatar
The design looks good but that won't matter when it comes to usability. No offence to anyone, but for that amount of money "hit and miss" and "close enough" is unacceptable. Pinpoint stars and sharpness should be a bare minimum. We as consumers should never accept anything less, but that's just my opinion. It's a lot more expensive than a high quality Esprit 100..

TLDR; A £2300 telescope shouldn't need a $99 plugin to work properly.