34 replies to this topic

[Atlantic Devil]

My Orion StarBlast and SkyScanner are both f/4 scopes. From what I’m learning, very fast scopes do better with eyepieces that can handle that range. Any recommendations on what these eyepieces would be? I’ll probably keep it in the 20mm - 32mm range.

[f74265a]

Generally speaking, very, very expensive eyepieces are better corrected for fast f ratio telescopes, at least those with a decent afov. I’m not at all confident that it is worth investing in quality eyepieces for these two inexpensive, entry level telescopes, but that’s not my decision. I believe your other post says you have an xt8 that’s closer to f6. Seems more sensible to me to invest in eyepieces for that.

[StarryHill]

The Orion Sirius eyepieces are good values and good quality. They should work fine with your scopes. Their field of view is fairly narrow at 52mm. To go wider and have good quality with an f/4 could mean eyepieces that cost more than your telescopes.

 

You mentioned a range of 20mm to 32mm.... the exit pupil (width of the beam of light coming out of the eyepiece and into your eye) is getting pretty wide in the upper part of this range. At some point, the blockage in the light path caused by your secondary mirror will become large enough to be visible as a dark smudge in the middle of your field of view. A good rule of thumb is to not go wider than 7 times your focal ratio, or 28mm in your case. Personally, I probably would not exceed 25mm.

Edited by StarryHill, 29 November 2020 - 01:47 AM.

[SeattleScott]

At F4 you don’t really want to go higher than around 25mm FL. By far the best low power eyepiece for a scope like this for under $100 is the 25mm Celestron Xcel LX. Now if you have $300 to spend in order to get something 20% better, let us know and the recommendations will start pouring in.

Scott

[havasman]

Best performance at f4 - Ethos, Naglers, Morpheus, ES92, ES82, ES100, APM HDC, APM UFF, etc. All used with Paracorr/Paracorr 2.

Yes, buy for the 8" if you have it. Consider putting your scopes in your signature line by clicking on your name in top right corner of the page, my profile, edit profile, signature.

[jjack's]

https://www.teleskop...connection.html

this serie look like a rebadged vixen LVW.

Edited by jjack's, 29 November 2020 - 11:39 AM.

[SeattleScott]

Best performance at f4 - Ethos, Naglers, Morpheus, ES92, ES82, ES100, APM HDC, APM UFF, etc. All used with Paracorr/Paracorr 2.
Yes, buy for the 8" if you have it. Consider putting your scopes in your signature line by clicking on your name in top right corner of the page, my profile, edit profile, signature.

He listed both his scopes. These eyepieces are all more expensive than either of his scopes and a paracorr won’t work in a 1.25” focuser. Recommending eyepieces for a 20” F4 Starmaster is different than recommending eyepieces for a Starblast or Skyscanner.

Scott

Edited by SeattleScott, 29 November 2020 - 11:39 AM.

[ShaulaB]

A Celestron 8-24mm zoom eyepiece will be a great accessory for you. In my metro area, around 200 of the 4.5 inch StarBlast scopes are in the library systems for patrons to check out like books. All these scopes are outfitted with the Celestron zoom eyepiece. It's under $100. Have fun with your scopes!

[Starman1]

https://www.teleskop...connection.html

this serie look like a rebadged vixen LVW.

Those are the ubiquitous Barsta 70° series that first appeared as the Celestron Ultima LX, then the Astrotech AF70, then innumerable brand names like Olivon 70, Astromania SW, et.al.

Made in China (LVWs were made in Japan), and not duplicates of the LVW, though obviously modified copies of them, given similar focal lengths.

 

I go along with the suggestion that simple Plössls are the most cost-effective eyepieces here, given the OP's scopes.

Or maybe the 58-60° eyepieces available for $60-$80 each if the OP feels like splurging.  Expensive eyepieces make no sense in recommendations.

[vdog]

I used to have a Starblast. The recommended Celestron Zoom was actually my main eyepiece for that scope.  I enjoyed a lot of targets with that combo.  It won't give you a wide angle view, though, if that's what you're looking for, as it's about 40 degrees at the high end.

 

If I were looking for a max focal length, wide-FOV eyepiece for that scope now, I'd probably get that 70 degree 22mm recommended above.

[Atlantic Devil]

I currently have that kit from celestron that comes with 8, 6, 13, 17, and 32mm eyepieces, a 2x Barlow and some color filters. I'm going to order some of the celestron  x-cel LX eye pieces. The thing is I don't know which of my current eye pieces should really be replaced. I also have 10, 20, and 25 Orion Sirius plossl  eye pieces.

[SeattleScott]

I currently have that kit from celestron that comes with 8, 6, 13, 17, and 32mm eyepieces, a 2x Barlow and some color filters. I'm going to order some of the celestron x-cel LX eye pieces. The thing is I don't know which of my current eye pieces should really be replaced. I also have 10, 20, and 25 Orion Sirius plossl eye pieces.

The priority would be replacing the 32mm Plossl with the 25 Xcel LX in Oder to get a more reasonable exit pupil at F4. After that I would look at what plossls have uncomfortable eye relief for you, maybe 10mm and shorter FL, and upgrade to the Xcel 9 or 7 or something.

Scott

[jjack's]

Those are the ubiquitous Barsta 70° series that first appeared as the Celestron Ultima LX, then the Astrotech AF70, then innumerable brand names like Olivon 70, Astromania SW, et.al.

Made in China (LVWs were made in Japan), and not duplicates of the LVW, though obviously modified copies of them, given similar focal lengths.

 

I go along with the suggestion that simple Plössls are the most cost-effective eyepieces here, given the OP's scopes.

Or maybe the 58-60° eyepieces available for $60-$80 each if the OP feels like splurging.  Expensive eyepieces make no sense in recommendations.

Good information as usual Don. Thanks.

They say they are good to f/4. They are surely wrong ! The eyepieces you quote are not.

[Starman1]

Good information as usual Don. Thanks.

They say they are good to f/4. They are surely wrong ! The eyepieces you quote are not.

True, but eyepieces that ARE good to f/4 will be more expensive than can be justified for the economical scopes in question.

Even TeleVue Delites, which are good to f/4 and would be great candidates, are too expensive to be justified for these scopes.

I blame the manufacturers of scopes that they would even make entry level newtonian scopes below f/6 because the coma will be severe even if the eyepiece is well corrected at f/4,

and the eyepieces used with these scopes likely won't be.

 

Plössls would be a good compromise and quite affordable.

[Thomas_M44]

True, but eyepieces that ARE good to f/4 will be more expensive than can be justified for the economical scopes in question.

Even TeleVue Delites, which are good to f/4 and would be great candidates, are too expensive to be justified for these scopes.

I blame the manufacturers of scopes that they would even make entry level newtonian scopes below f/6 because the coma will be severe even if the eyepiece is well corrected at f/4,

and the eyepieces used with these scopes likely won't be.

 

Plössls would be a good compromise and quite affordable.

Exactly.

 

It's just this kind of lower price-point, fast f-ratio scope scenario in which better-quality Plossl's can be an attractive option.

 

A set of eyepieces costing $200 apiece or more for use in a $200 to $400 telescope --that's difficult value proposition.

[Atlantic Devil]

The priority would be replacing the 32mm Plossl with the 25 Xcel LX in Oder to get a more reasonable exit pupil at F4. After that I would look at what plossls have uncomfortable eye relief for you, maybe 10mm and shorter FL, and upgrade to the Xcel 9 or 7 or something.

Scott

I read that the 32mm that comes with that kit is actually pretty good. But since i have nothing to compare it to, i cant tell for sure.

[Atlantic Devil]

Well, i just ordered an Agena Starguider Dual ED 12mm. Supposedly, they are really good. Guess I'll find out soon.

[SeattleScott]

I read that the 32mm that comes with that kit is actually pretty good. But since i have nothing to compare it to, i cant tell for sure.

The 32mm that comes with it is probably a fine eyepiece. But a 32mm Brandon wouldn’t be a good match for a F4 scope. It isn’t an issue of the eyepiece quality. It is an issue of the eyepiece focal length relative to your scope’s F ratio.

But the 12mm paradigm should be a nice improvement and an introduction to 60 AFOV eyepieces. It just wouldn’t have been my first choice personally. Not saying you could do much better without spending much more money. I just would have prioritized low power or replacing a higher power Plossl with uncomfortable eye relief.

Scott

[Atlantic Devil]

The 32mm that comes with it is probably a fine eyepiece. But a 32mm Brandon wouldn’t be a good match for a F4 scope. It isn’t an issue of the eyepiece quality. It is an issue of the eyepiece focal length relative to your scope’s F ratio.

But the 12mm paradigm should be a nice improvement and an introduction to 60 AFOV eyepieces. It just wouldn’t have been my first choice personally. Not saying you could do much better without spending much more money. I just would have prioritized low power or replacing a higher power Plossl with uncomfortable eye relief.

Scott

The new lens is mainly going to be for my StarNavigator. That one is an f/13.8 and a 12mm is probably the highest magnification I'll use on it as going over 105x probably won't do me any favors.

[SeattleScott]

Valid point.

[Atlantic Devil]

I'm wondering if a 4mm Agenda Starguider Dual ED will be too high for my F\4 scopes...

[SeattleScott]

Nah. Not if you collimate them.

[Atlantic Devil]

I thought there were 4mm Starguider eyepieces. Looks like there isn’t. I’ll probably just go with a 5mm Starguider or X-Cel LX.

[SeattleScott]

You could also keep an eye on the classifieds for one of the vintage Japanese 3.8mm models (several brands). Quite sharp and available at bargain prices. They aren’t wide AFOV but they are sharp and have usable eye relief. 3.8mm would be a reasonable jump from 5mm.

Note the Xcel LX 5mm is really 4.5mm. I recently read a rather poor review of this eyepiece so the 5mm paradigm might be a safer bet.

Scott

[vdog]

I'm wondering if a 4mm Agenda Starguider Dual ED will be too high for my F\4 scopes...

In my Starblast, I used a 3mm eyepiece for 150x magnification.  Collimation had to be spot on, but I was able to observe the Cassini division, Titan, the Great Red Spot, and subtle hints of the maria on Mars with that combo.

 

It was pretty much just for the moon and planets, though.  Everything else was pretty dim at that magnification.

Edited by vdog, 01 December 2020 - 01:24 PM.