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Pentax 40 vs Televue 41 for F/10 SCT 8"

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#1 Calibiz

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Posted 06 August 2022 - 02:04 PM

Hello. Considering these 2 eyepieces. Would love some recommendations for an SCT at f/10 8". I've seen some forum posts, but not enough specifically for my scope.

 

I've heard the TV has less field curvature. However many people said even with the field curvature of a c8, the Pentax wasn't noticeable. But it seems the Pentax has more, not ideal for an SCT.

 

I've heard the TV has the clearer edges.

 

While they are 40,41, the AFOV is apparently the same.

 

The one thing that HAS been pushing me to the Pentax is I heard it has better contrast. However I'm not sure if this is true. If it does have better contrast, I'd be willing to take

that over slightly better edges. The weight of the TV doesn't bother me as I'm using it on a nice EQ mount. The cost doesn't bother me as much either, I sold a few of my other toys to afford one of these babies, so I'd rather get the better oner regardless off 100-125 bucks.

 

I plan to use with an Astronomik UHC and Oiii filter.

 

I live in Bortles 7 skies.

Cost and weight aside, all things being equal, which one is the better buy for me?



#2 eyeoftexas

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Posted 06 August 2022 - 02:46 PM

I would consider instead the AstroTech 82° 28mm.  It's getting rave reviews (https://www.cloudyni...otech-28mm-uwa/).  It will give you almost the same TFOV, and importantly at higher magnification so your skies will be darker.  The two you're considering will be lower magnification, and hence the background skies will be brighter [I know, I live under Bortle 8ish skies].

 

I do have the Pentax 40mm and like it a lot.  I never used the Pan 41, so I cannot speak to their differences.



#3 SeattleScott

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Posted 06 August 2022 - 02:58 PM

The Pentax is significantly lighter. At F10 there probably won’t be much difference in edge performance.
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#4 Calibiz

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Posted 06 August 2022 - 04:21 PM



I would consider instead the AstroTech 82° 28mm.  It's getting rave reviews (https://www.cloudyni...otech-28mm-uwa/).  It will give you almost the same TFOV, and importantly at higher magnification so your skies will be darker.  The two you're considering will be lower magnification, and hence the background skies will be brighter [I know, I live under Bortle 8ish skies].

 

I do have the Pentax 40mm and like it a lot.  I never used the Pan 41, so I cannot speak to their differences.

Thanks for the response. One of the reasons I'm considering a 40+ MM eyepiece is to have a 4mm exit pupil. Otherwise I'd consider a 28mm eyepiece.



#5 Calibiz

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Posted 06 August 2022 - 04:21 PM

The Pentax is significantly lighter. At F10 there probably won’t be much difference in edge performance.

As I said, I'm using an EQ mount so weight isn't really a problem for me.



#6 RyanAstroMan  Happy Birthday!

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Posted 06 August 2022 - 06:26 PM

I have the pentax 40mm xw and it is very nice! The eye relief is very comfortable even when observing with glasses. I have an 8" acf sct and it works wonderfully but I also use it on a 5 inch refractor. I was worried about field curvature as well but discovered that I am personally not sensitive to it. If your looking for it then you will probably see it. And if you want the best of the best then the 41 pan it is. But the pentax is not bad by any means. Just remember that f10 is very forgiving on eyepieces, I've compared my xw with my william optics 40mm swan and the Swan is excellent as well with some minor astigmatism off axis that was from my own eyes.
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#7 GGK

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Posted 06 August 2022 - 06:35 PM

Hello. Considering these 2 eyepieces. Would love some recommendations for an SCT at f/10 8". I've seen some forum posts, but not enough specifically for my scope.

 

I've heard the TV has less field curvature. However many people said even with the field curvature of a c8, the Pentax wasn't noticeable. But it seems the Pentax has more, not ideal for an SCT.

 

I've heard the TV has the clearer edges.

 

While they are 40,41, the AFOV is apparently the same.

 

The one thing that HAS been pushing me to the Pentax is I heard it has better contrast. However I'm not sure if this is true. If it does have better contrast, I'd be willing to take

that over slightly better edges. The weight of the TV doesn't bother me as I'm using it on a nice EQ mount. The cost doesn't bother me as much either, I sold a few of my other toys to afford one of these babies, so I'd rather get the better oner regardless off 100-125 bucks.

 

I plan to use with an Astronomik UHC and Oiii filter.

 

I live in Bortles 7 skies.

Cost and weight aside, all things being equal, which one is the better buy for me?

I use a 40mm Pentax XW in my SCT and all my refractors for the widest possible field of view. The image in my old C8 and present C9.25 is excellent. 
 

I have no doubt that the 41mm Panoptic is also excellent, but I don’t have one. 
 

The 40mm XW will give about 1.2+ degree field of view in the C8 depending on the optical length of the visual back and diagonal. It does well with my Lumicon OIII and UHC filters. 
 

The eye relief and eyecup design of the XW works very well for me personally. ( I do not wear glasses, but like the long eye relief with the extendible eye cup)
 

Gary



#8 vdog

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Posted 06 August 2022 - 07:40 PM

Before purchasing the XW 40, I flirted with the idea of getting the Panoptic, and I read through every comparison thread I could find.  Price and weight came up a lot, but you don't care about those.  Field curvature vs. sharp to the edges also came up a lot.  I don't remember reading anything about contrast, but it may have been there and I just don't remember.

 

Anyway, I went with the XW and I use it in f/6.9 and f/7.5 refractors and while I see a teeny bit of FC at the very edges, it's not enough to bother me.  I have no regrets.  For me, that is one sweet wide-angle refractor eyepiece.

 

So, it may come down to whether or not you will have regrets.  If you choose the XW, but could have afforded the Pan, will you always wonder if it would have been better?  


Edited by vdog, 06 August 2022 - 07:58 PM.


#9 turtle86

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Posted 06 August 2022 - 11:14 PM

Hello. Considering these 2 eyepieces. Would love some recommendations for an SCT at f/10 8". I've seen some forum posts, but not enough specifically for my scope.

 

I've heard the TV has less field curvature. However many people said even with the field curvature of a c8, the Pentax wasn't noticeable. But it seems the Pentax has more, not ideal for an SCT.

 

I've heard the TV has the clearer edges.

 

While they are 40,41, the AFOV is apparently the same.

 

The one thing that HAS been pushing me to the Pentax is I heard it has better contrast. However I'm not sure if this is true. If it does have better contrast, I'd be willing to take

that over slightly better edges. The weight of the TV doesn't bother me as I'm using it on a nice EQ mount. The cost doesn't bother me as much either, I sold a few of my other toys to afford one of these babies, so I'd rather get the better oner regardless off 100-125 bucks.

 

I plan to use with an Astronomik UHC and Oiii filter.

 

I live in Bortles 7 skies.

Cost and weight aside, all things being equal, which one is the better buy for me?

 

I have the 41mm Pan and it yields superb low power views in my scopes. Nice flat field out to the edge.  The only downsides are weight and cost, which don't sound like important factors for you.

 

I haven't tried the Pentax 40 XW myself but have no doubt that it's also excellent.



#10 Traveler

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Posted 07 August 2022 - 12:07 AM

The Pentax 40 XL is even lighter then the XW.

I use it every time when observing with my C8 or C9.25... As a bonus It is also in use as a finder ep for my refrators (well actually,  i bought it for using as a finder ep).



#11 25585

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Posted 07 August 2022 - 07:51 AM

ES68 40mm is another choice, or a Vixen LVW 42mm if you want lighter.



#12 JimOfOakCreek

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Posted 07 August 2022 - 08:59 AM

I’ve had the 40mm XW for around two years. It’s near perfect in my 8” SCT. There are some imperfections at outer 10% in my F7 APO. Keep in mind that FC and astigmatism varies with the eyes of each observer. 
 

Ergonomics are excellent, lightweight for its size. On balance the 40mm XW is a pretty good eyepiece.


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#13 RAKing

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Posted 07 August 2022 - 10:03 AM

I have owned both of these and used them both in my SCTs and Maks.  They both work well, but I stayed with the Pentax series because they are more comfortable to use.  Optically, they are both excellent, but Pentax has the better ergonomics for me.

 

The Panoptic series has progressive eye relief and by the time you get out to the 41mm, the ER is a whopping 27mm.  Unless you like to "hover" over the eyepiece without touching it while you are using it, you might find it more difficult to keep your eye in the right place.  The Pentax XW series all have consistent 20mm eye relief and easy-to-use, comfortable eye guards.  I can unscrew the eye guard to put my eye in the right place - and it will stay there!  The Pentax is also lighter and easier for me to handle.

 

My .02,

 

Ron



#14 Calibiz

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Posted 07 August 2022 - 11:15 AM

I have owned both of these and used them both in my SCTs and Maks.  They both work well, but I stayed with the Pentax series because they are more comfortable to use.  Optically, they are both excellent, but Pentax has the better ergonomics for me.

 

The Panoptic series has progressive eye relief and by the time you get out to the 41mm, the ER is a whopping 27mm.  Unless you like to "hover" over the eyepiece without touching it while you are using it, you might find it more difficult to keep your eye in the right place.  The Pentax XW series all have consistent 20mm eye relief and easy-to-use, comfortable eye guards.  I can unscrew the eye guard to put my eye in the right place - and it will stay there!  The Pentax is also lighter and easier for me to handle.

 

My .02,

 

Ron

Ron,

 

That's a great point. I hate when everyone equates that more eye relief is better. Since I don't wear glasses, lower eye relief is better for me. I like putting my face as close as I can to the scope.

 

Think your comment might have steered me towards the Pentax!

Are they pretty similar as far as star sharpness/contrast?

Eric


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#15 Bill Barlow

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Posted 07 August 2022 - 11:31 AM

I once owned both of these eyepieces at the same time and did comparisons in a C14 several years ago.  I looked at several different objects like globular cluster, galaxies and the double cluster.  What I found is that both put up excellent images, but the Pentax 40XW was slightly more immersive, three dimensional with slightly better contrast in its views.  Probably can’t go wrong with either one.

 

Bill


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#16 swsantos

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Posted 07 August 2022 - 11:42 AM

I have owned both of these and used them both in my SCTs and Maks.  They both work well, but I stayed with the Pentax series because they are more comfortable to use.  Optically, they are both excellent, but Pentax has the better ergonomics for me.

 

The Panoptic series has progressive eye relief and by the time you get out to the 41mm, the ER is a whopping 27mm.  Unless you like to "hover" over the eyepiece without touching it while you are using it, you might find it more difficult to keep your eye in the right place.  The Pentax XW series all have consistent 20mm eye relief and easy-to-use, comfortable eye guards.  I can unscrew the eye guard to put my eye in the right place - and it will stay there!  The Pentax is also lighter and easier for me to handle.

 

My .02,

 

Ron

I don’t own one, but my understanding is that the 41mm Panoptic is adjustable so that the right eye relief can be dialed in and that that feature is unique to that focal length in the Panoptic line. The description of the eyepiece on Televue’s website states  that and I believe that I have read reviews of it that describe it that way.



#17 astrophile

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Posted 07 August 2022 - 11:49 AM

The Pan 41 eyecup height is indeed adjustable. I have owned both, the XW is gone and the Panoptic remains—in my case, largely due to FC issues with the XW. That is definitely observer- and scope- dependent, of course.

I noticed no contrast difference between the two.

Edited by astrophile, 07 August 2022 - 11:49 AM.

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#18 Calibiz

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Posted 07 August 2022 - 12:30 PM

The Pan 41 eyecup height is indeed adjustable. I have owned both, the XW is gone and the Panoptic remains—in my case, largely due to FC issues with the XW. That is definitely observer- and scope- dependent, of course.

I noticed no contrast difference between the two.

So to clarify..The eyecup is adjustable, but the ER stays at 27mm right? 



#19 rguasto

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Posted 07 August 2022 - 12:42 PM

A 41 pan is extremely well corrected. Not much more to say.

-Rob
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#20 astrophile

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Posted 07 August 2022 - 03:47 PM

So to clarify..The eyecup is adjustable, but the ER stays at 27mm right? 

Yes.



#21 swsantos

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Posted 07 August 2022 - 04:32 PM

Yes.

But if properly adjusted I imagine you would not need to hover over the eyepiece, which to me is the annoying part about too much ER, you could be comfortably up against the eyecup if desired…


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#22 astrophile

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Posted 07 August 2022 - 05:24 PM

But if properly adjusted I imagine you would not need to hover over the eyepiece, which to me is the annoying part about too much ER, you could be comfortably up against the eyecup if desired…


…and Yes.

#23 astrophile

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Posted 07 August 2022 - 05:29 PM

The Pan 41 is unlike any other Panoptic in that the conic housing for the eyecup screws up and down to enable desired placement of one’s eye socket (or glasses). It’s the only current Pan I know to do this. Being of the non-eyeglasses, snuggle-into-the-eyeguard camp, I have to use a TV Extender on the Pan 35, for example.
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#24 Echolight

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Posted 07 August 2022 - 06:14 PM

I got the XW40 because it weighs about 8 or 9 ounces less. And it was on sale.

 

The build quality and design are terrific.


Edited by Echolight, 07 August 2022 - 06:33 PM.

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#25 thecelloronin

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Posted 07 August 2022 - 10:39 PM

You might consider the Lacerta ED 40mm, a rebranding of the TMB Paragon 40mm. I had to order mine from a store in Austria for about $200 shipped, but I have no regrets. Generous ~68* FOV, comfortable eye relief made even easier with a twist up eyecup, good edge performance at F7 and nice transmission. Mine weighs 498g.

 

https://teleskop-aus...eyepiece-2-inch

 

I might be totally off base but at f/10 I reckon paying for a Panoptic or ES is throwing money away. The Lacerta was my cheapskate answer to the Pentax.


Edited by thecelloronin, 07 August 2022 - 11:33 PM.

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