29 replies to this topic

[SpacedOut31416]

I'm looking to purchase a wide angle eyepiece and was hoping someone would have some experience and/or insight as to which one of these might be preferable.

 

The price for either is around $270 (i.e., in my price range).

 

They both have similar FOVs (about 70 degrees).

 

The eye relief on the Pentax spec says 20mm, and the TeleVue spec says 13mm.

 

The weight on the Pentax is about 13 oz vs the TeleVue of about 7 oz.

 

Any thoughts, insight, experience, etc. is greatly appreciated, and many thanks for your time.

 

Roy

Edited by SpacedOut31416, 22 September 2023 - 06:37 PM.

[areyoukiddingme]

The XW 20 has field curvature--stars won't be focused at the edge and center at the same time--if you put it in the relatively fast focal ratio scopes.

 

I found with a 6" F8 refractor, the 20XW was flat all the way across. If you use it with a coma corrector, that also decreases but does not eliminate the FC. But I do see a good amount in my faster refractors, for example.

 

So the scope matters quite a lot. What scope(s) are you using?

 

I don't have the 19 Panoptic, but would guess that it is good all the way across the field in most scopes.

[SpacedOut31416]

I'm using an 80mm triplet refractor with a 480mm focal length. Many thanks for your insights!

Edited by SpacedOut31416, 23 September 2023 - 12:51 PM.

[SeattleScott]

Kind of the point of the XW is the long eye relief, either to accommodate glasses or just for those who prefer big eye lens with easy views.

 

The Panoptics are better corrected in fast scopes than the 20XW. And lighter. Some prefer the smaller form factor.

[SpacedOut31416]

Many thanks for your insights!

[25585]

An alternative to consider is the 18mm or 24mm APM UFF eyepiece. Both are flat field, and have longer eye relief, closer to the Pentax.

Edited by 25585, 22 September 2023 - 07:41 PM.

[SpacedOut31416]

Thanks very much for this tip! I haven't heard of these eyepieces - so this is really good info.

 

Roy

[areyoukiddingme]

I'm using an 80mm triplet refractor with a 480mm focal length. Many thanks for your insights!.

I have an 80mm F6, and yes, you'll see field curvature in that for pretty much everything you put in there, but especially the 20 XW.

 

Having said that, I do really like the 20 XW. It's a matter of what you can tolerate as aberrations, and people vary on that.

 

I don't mind a bit of FC, because I can accommodate it still reasonably well, and I like comfort, which the XW has in spades.

[SpacedOut31416]

Thanks Scott for your help on this! Your firsthand experience is appreciated.

 

Roy

[Speedy1985]

For $275 from the sponsor of this site, you have the Astrotech XWA 20mm as an option too. They are excellent eyepieces, made by the same manufacturer as the APM XWA and Stellarvue Optimus. And they are 100 degree FOV. If you do a search on here, you'll see that it is highly regarded. 

[SpacedOut31416]

My scope is an Astro-Tech, so I know their products and service are a great value. Thanks Don for the info on those eyepieces! 

[SeattleScott]

Do realize that hyperwides are massive and can cause balance issues with small scopes. Also I don’t know that 100 AFOV is going to help any with the scope’s inherent FC.

[SpacedOut31416]

Thanks for your insights, Scott!

 

I have extra counterweights on hand when needed, because my main eyepiece is a Baader Hyperion zoom. Actually, taking a closer look at the spec, that Baader seems to be fairly wide angle at low power*.

 

However, I was under the impression that a good static eyepiece would produce a somewhat better image than a zoom at the same focal length??

 

Roy

 

*Later edit: I realized later I was interpreting the spec backwards (i.e., thinking low power resulted in wider angles in that zoom eyepiece - when in reality it was the opposite).

Edited by SpacedOut31416, 24 September 2023 - 09:19 AM.

[Tank]

Better edge correction in the pans

FC in the 20 XW

 

If you wan more ER

I would look to the Delos

Baader morps are pretty good too

[Tank]

Roy and yes the staic eypiece will be better than the zoom at the 20mm FL

[SpacedOut31416]

Many thanks Tony! Clear skies to you.

[RAKing]

I have both eyepieces and both are great.  Personally, I think the "FC issue" in the Pentax XW is overblown.  It depends on how well or (not well) your eyes can accommodate field curvature.  I am 76 years old and can easily accommodate what little FC there is in the eyepiece and consider it to be a very comfortable eyepiece to use.

 

But having said that, I also use and like the Televue 19mm Panoptic.  It is also excellent, and it is smaller and lighter than the Pentax.  The advantage for the Panoptic is I can easily use two 19mm Panoptics in my binoviewers, whereas the XW are too big for me to use in the binoviewers - my eyes are too close together.

 

If I was monoviewing, I would definitely stick with the more comfortable Pentax, but for binos, the Pans are the way to go.

 

Cheers,

 

Ron

[SeattleScott]

Thanks for your insights, Scott!

I have extra counterweights on hand when needed, because my main eyepiece is a Baader Hyperion zoom. Actually, taking a closer look at the spec, that Baader seems to be fairly wide angle at low power.

However, I was under the impression that a good static eyepiece would produce a somewhat better image than a zoom at the same focal length??

Roy

The BHZ is fairly wide at high power but it could use a wide low power compliment, such as a 20XW or 19 Panoptic.

[SpacedOut31416]

I have both eyepieces and both are great.  Personally, I think the "FC issue" in the Pentax XW is overblown.  It depends on how well or (not well) your eyes can accommodate field curvature.  I am 76 years old and can easily accommodate what little FC there is in the eyepiece and consider it to be a very comfortable eyepiece to use.

 

But having said that, I also use and like the Televue 19mm Panoptic.  It is also excellent, and it is smaller and lighter than the Pentax.  The advantage for the Panoptic is I can easily use two 19mm Panoptics in my binoviewers, whereas the XW are too big for me to use in the binoviewers - my eyes are too close together.

 

If I was monoviewing, I would definitely stick with the more comfortable Pentax, but for binos, the Pans are the way to go.

 

Cheers,

 

Ron

Ron - Thanks for your insight and taking the time to reply. Telescopic bino-viewing sound like a lot of fun. Whishing many more nights of clear skies to you, sir!

 

Roy

[SpacedOut31416]

The BHZ is fairly wide at high power but it could use a wide low power compliment, such as a 20XW or 19 Panoptic.

Thanks to you, Scott!

 

Do you have any experience with the Tele Vue DeLite Series 18.2mm Eyepiece?

 

It's not quite as wide angle as as the 19 Panoptic (62 degrees) but has eye relief of 20 mm.

 

Roy

[SeattleScott]

Thanks to you, Scott!

Do you have any experience with the Tele Vue DeLite Series 18.2mm Eyepiece?

It's not quite as wide angle as as the 19 Panoptic (62 degrees) but has eye relief of 20 mm.

Roy

I don’t have experience with the Delite but there are a number of good options. Delite, 17.5 Morpheus, 17.3 Delos (might be a little heavy for a small scope?), or Nikon 17.5 SW if you want to keep it small and light but still 72 AFOV, although ER isn’t quite 20mm. Nikons basically have the AFOV of Delos with the weight and form factor and price of Delite.

[SeattleScott]

Honestly you might even consider Baader Hyperion 17mm. Long ER and advertised 68 AFOV. And affordable. Probably not quite premium grade but your scope isn’t going to be sharp to the edge anyway. The 17 is considered one of the best in the series and a respectable performer for half the price of premium brands. Given the scope is somewhat compromised anyway, it could be a good value pick. Now if you plan to upgrade to an F5 Dob then maybe stay with premium brands.

[SpacedOut31416]

Thanks Scott for taking the time to respond and all of the good advice!

 

Roy

[areyoukiddingme]

I have both eyepieces and both are great.  Personally, I think the "FC issue" in the Pentax XW is overblown.  It depends on how well or (not well) your eyes can accommodate field curvature.  I am 76 years old and can easily accommodate what little FC there is in the eyepiece and consider it to be a very comfortable eyepiece to use.

 

But having said that, I also use and like the Televue 19mm Panoptic.  It is also excellent, and it is smaller and lighter than the Pentax.  The advantage for the Panoptic is I can easily use two 19mm Panoptics in my binoviewers, whereas the XW are too big for me to use in the binoviewers - my eyes are too close together.

 

If I was monoviewing, I would definitely stick with the more comfortable Pentax, but for binos, the Pans are the way to go.

 

Cheers,

 

Ron

OP's scope is an 80mm F6. I'd be surprised if he can accommodate FC in the 20XW. 

 

I have that size scope, and find that to get a star in focus at the edge and in the center of the 20XW, I'm doing close to a 1/2 turn on the fine focus knob. For my 50 year old eyes, the FC in that scope is obvious. I could see how someone would find that a deal breaker.

 

In my 125mm F7.8, I still see a little FC, but it's less. More like 1/4 turn on fine focus to get FC removed. In that case, the trick of focusing about half way out from the edge is quite effective.

[Apnee44]

I'm using an 80mm triplet refractor with a 480mm focal length. Many thanks for your insights!

With my ST80 (80/400), the most used eyepiece is an ES 24mm 68 and a Radian 12. In your case a 24mm 68deg such as Explore Scientific ot fron APM will be a better option as it will give the max field you can get with a 1.25’’ eyepiece. I tried my Radian 18mm on it, it works very well, but I do not feel the need of it. I had in the past one Panoptic 19 and found it a WoW eyepiece… but I sold it as I could see that I was not using it.