90mm refractor Diagonal & eyepieces recommendation

[darkage (Gareth)]

Hi Guys,

I managed to pickup a Celestron Astro Fi 90 WiFi Refractor for $20 missing diagonal & eyepieces. Just wondering whats the best diagonal & recommended eyepiece that wont break the bank but still provide good performance.

I do have a tasco 59mm from the 80's that have a diagonal & eyepieces have to hunt around for it. not sure if that would be good enough or better to buy something newer.

My interests would be watching moon, planets & generally checking out interesting objects

[Pierre_C]

Hi Gareth.

I do not have experience with the Astro Fi 90, but keeping with the brand I would suggest the Celestron 1.25” star diagonal Item 94115-A and Celestron Omni eyepieces. I have had good experiences with both on a similar telescope.

There are cheaper options, but you generally get what you pay for.

Regards,
Pierre C.

[Saturnine (Jeff)]

Only 1 reply so far, which is a bit disappointing. Any 1.25" diagonal from Celestron, Skywatcher ,GSO, SVBony etc. are all very similar and will suit the telescope. Unless you want to go upmarket and get Williams Optics or Takahashi or similar premium brands, which would be overkill in this case unless you intend to upgrade telescopes to a premium brand in the future.
As for eyepieces, depends on the budget, A reasonable middle of the road set of SWA eyepieces like the Dual EDs' in various focal lengths like 25mm 15mm, 8mm would be a suitable range of magnifications.
https://www.ebay.com.au/itm/19156515...YAAOSwjRpZUzNq

[refractordude]

Hello There Jeff


GSO 32mm Plossl, GSO SuperView 20mm, Duel Ed 15mm, Duel ED 8mm, and Duel ED 5mm. I also like the GSO 20mm Plossl. Plossl eyepieces below 20mm have terrible eye relief.


GSO 1.25" 90 degree 99% dielectric diagonal.

[Leo.G (Leo)]

That sounds like an incredible buy.



Quick question, the Tasco eyepiece and diagonal, are they 1.25" or the older .96" units?
If they are the smaller units standard with Tasco gear in the 80s to early 90s I found mine weren't great quality (especially the 4mm which I'd still have here, heaven knows why, all of the original eyepieces I'd have because I replaced them with much higher quality stuff and eventually gave them to a sister with a small scope with the original Tasco 80mm refractors focuser fitted).
I convinced a friend to buy a cheap, used GSO set of eyepieces some time ago and must admit they are amazing quality.

[darkage (Gareth)]

Originally Posted by Leo.G

That sounds like an incredible buy.



Quick question, the Tasco eyepiece and diagonal, are they 1.25" or the older .96" units?
If they are the smaller units standard with Tasco gear in the 80s to early 90s I found mine weren't great quality (especially the 4mm which I'd still have here, heaven knows why, all of the original eyepieces I'd have because I replaced them with much higher quality stuff and eventually gave them to a sister with a small scope with the original Tasco 80mm refractors focuser fitted).
I convinced a friend to buy a cheap, used GSO set of eyepieces some time ago and must admit they are amazing quality.

Thanks for the reply

Yep woke up one Sunday and immediately got out of bed and jumped on the deal. Originally was thinking it was a typo and missing a zero, but no it was $20. I always wanted a goto.

Your absolutely correct my old tasco gear is .96" when I was a kid I would spend between 2 hours to 4 hours a session with my old tasco.. I thought it was pretty good back then.. so anything better is a plus.

I was thinking of picking up the SVBony Red line set or maybe Gold line along with SVBony diagonal. Seems like best bang for buck to start out again. Was a little worried about kidney beaning effects reported on forums. I'll check out GSO prices as well.

[darkage (Gareth)]

Originally Posted by Saturnine

Only 1 reply so far, which is a bit disappointing. Any 1.25" diagonal from Celestron, Skywatcher ,GSO, SVBony etc. are all very similar and will suit the telescope. Unless you want to go upmarket and get Williams Optics or Takahashi or similar premium brands, which would be overkill in this case unless you intend to upgrade telescopes to a premium brand in the future.
As for eyepieces, depends on the budget, A reasonable middle of the road set of SWA eyepieces like the Dual EDs' in various focal lengths like 25mm 15mm, 8mm would be a suitable range of magnifications.
https://www.ebay.com.au/itm/19156515...YAAOSwjRpZUzNq

I wasn't sure if I should stick with same brand Celestron but I think it should be okay any decent brand. If I get hooked again I will most likely in future go for Williams Optics or other brand of small APO refractor for astrophotography & tracking mount.

Thanks for your reply

[darkage (Gareth)]

Originally Posted by Pierre_C

Hi Gareth.

I do not have experience with the Astro Fi 90, but keeping with the brand I would suggest the Celestron 1.25” star diagonal Item 94115-A and Celestron Omni eyepieces. I have had good experiences with both on a similar telescope.

There are cheaper options, but you generally get what you pay for.

Regards,
Pierre C.

I was originally thinking of getting Celestron 9mm & 20mm eyepieces but its hard to refuse the bang for buck for SVBony & quality seems decent enough from reviews.

Thanks for the reply

[darkage (Gareth)]

Originally Posted by nate998

Awesome deal on the Astro Fi 90! For the diagonal, I'd stick with Celestron or GSO. The SVBony Red or Gold line eyepieces are solid options too. Just watch for kidney beaning. If you really get into it, those Dual EDs could be a great upgrade later.

Yes I heard of kidney beaning issue which makes me 2nd think svbony.


Would it be better to get a eyepiece kit. or maybe 9mm & 20 or 25mm just
https://www.bintel.com.au/product/ce...IaAsJKEALw_wcB

[Saturnine (Jeff)]

The Bintel eyepiece and filter kit, to me is overpriced and you really don't need the filters. The coloured filters are to help highlight different features on the planets and they do that to some degree but unless you are going to spend a lot of time studying the planets and with the 90mm scope you wont get deep enough detail to justify having the filters for that purpose.
I have a full set of coloured filters and honestly, I hardly use them. A good Contrast Booster Filter would be more suitable for your use as well as 3 or 4 medium quality wide angle eyepieces.

[Leo.G (Leo)]

Another mention, a Barlow of decent quality gives you twice the lens. If you have a 20mm lens and Barlow no point in getting a separate 10mm lens but many people will disagree with this logic and I have 20mm, 10mm, 5mm and Barlow so that probably makes me silly. I bought individual lenses before I could get the Vixen 2 times Barlow.

It boils down to how much you can afford to spend.

[Pierre_C]

Would it be better to get a eyepiece kit. or maybe 9mm & 20 or 25mm just
...celestron-eyepiece-filter-kit-1-25-inch... [/QUOTE]

I do not have direct experience with using the 90mm aperture, 910mm focal length, f/10.1 setup, but I think the maths suggests building around the 20mm eyepiece mark for x45 magnification (2mm exit pupil).

For higher magnification, a 9-10mm eyepiece for around x90-100 magnification sounds about right.

For lower magnification, I think the 25mm eyepiece for x36 magnification may be too similar to the 20mm eyepiece. I would suggest instead pushing further into the 32-40mm range for x22-28. This will also give you better wide field views.

[AstralTraveller (David)]

Originally Posted by refractordude

Hello There Jeff


GSO 32mm Plossl, GSO SuperView 20mm, Duel Ed 15mm, Duel ED 8mm, and Duel ED 5mm. I also like the GSO 20mm Plossl. Plossl eyepieces below 20mm have terrible eye relief.


GSO 1.25" 90 degree 99% dielectric diagonal.

Eyepiece comfort is a subjective judgement. I find 9-10mm eps are quite comfortable and I'm OK with my 7mm but find the 5mm a little too close for comfort. I'm taking about Parkes GS (a modified plossl) and Abbe orthos but the er is similar in those designs (and I used to use a 7.5mm plossl). Obviously you can get short focal length eps with long eye relief but at the cost of extra glass elements. This results in a degradation of the image, though only very slight in quality brands. Some say that the comfort offsets the image quality and in the end you see more. Others disagree.