Pentax SMC XL-Series 5.2mm?
Eugene Mroz
In article <tealEBq...@netcom.com>, teal
<teal#remove.this.to.reply#@netcom.com> wrote:
> Has anyone used the Pentax SMC XL-Series 5.2mm eyepiece? Does it really
> have a 65-degree apparent field? 20mm eye relief? Does it suffer any
> loss of image sharpness at the edges? Has anyone used it with a Barlow?
> If so, which one(s)? Thanks.
I have both the 5.2 mm and 10.5 mm Pentax SMC XL eyepieces. I haven't
actually measured either the apparent field nor the eye relief. However,
so far as eye relief is concerned, it is, as you may know, adjustable over
a very ample range. I find it to be satisfactory both with and without my
glasses but prefer the latter. Suggest you read Todd Gross' comprehensive
review at http://www.weatherman.com/nagler4.htm.
Nor have I compared these to other eyepieces of similar focal lengths.
But I haven't noticed any image degradation at the edges. However, in all
truthfulness, I don't use the 5.2 mm all that often on my Meade LX200 8"
SCT (f/10). This combination yields a magnification of ~384x and only
when seeing is excellent does it come out of my eyepiece case. However,
when that happens, such as earlier this week, I am able to split one of
the double stars in Lyra and can almost convince myself that I could split
the other as well. (I'm new enough at this enterprise of amateur
astronomy not to know whether I should : a) be pleased or b) join the
ranks of the Meade critics.)
I was also pleased with the the view of Martian topographic features a few
months ago (also on a night of good seeing) when Mars was much closer to
earth.
Fun to use for the moon, too.
Don't have a Barlow so I can't offer any insight there....but wouldn't
that result in a lot of "empty magnification"?
--
Gene Mroz + Voice: 505-667-7758
Chemical Science and Technology Division + Fax: 505-665-4955
Mail Stop: J514 + E-Mail: mr...@lanl.gov
Los Alamos National Laboratory
Los Alamos, NM 87545
"There is something fascinating about science.
One gets such wholesale returns of conjecture
out of such a trifling investment of fact."
Mark Twain from Life on the Mississippi
Todd Gross
In article <tealEBq...@netcom.com> teal <teal#remove.this.to.reply#@netcom.com> writes:
>From: teal <teal#remove.this.to.reply#@netcom.com>
>Subject: Pentax SMC XL-Series 5.2mm?
>Date: Fri, 13 Jun 1997 15:27:09 GMT
>Has anyone used the Pentax SMC XL-Series 5.2mm eyepiece? Does it really
>have a 65-degree apparent field? 20mm eye relief? Does it suffer any
>loss of image sharpness at the edges? Has anyone used it with a Barlow?
>If so, which one(s)? Thanks.
yes..all of the above, and more.. see my web page
there is nothing wrong with it, all claims are correct
Thanks! - Todd
_________________________________
BOSTON TV METEOROLOGIST TODD GROSS
Weather/Astronomy Home Page: http://www.weatherman.com
Administrator, Meade Advanced Product User Group: ma...@shore.net
Administrator, New England Weather Observer Mail List: wxob...@shore.net
IRC Channel Operator: #Weather (Undernet)
Originator of the NE.WEATHER newsgroup
_________________________________
Email: to...@weatherman.com Work Phone# (617)725-0777
Earle M. Kapchuk
In article <tealEBq...@netcom.com> teal <teal#remove.this.to.reply#@netcom.com> writes:
>
>Has anyone used the Pentax SMC XL-Series 5.2mm eyepiece? Does it really
>have a 65-degree apparent field? 20mm eye relief? Does it suffer any
>loss of image sharpness at the edges? Has anyone used it with a Barlow?
>If so, which one(s)? Thanks.
While not the 5.2 I've used the 10.5 for a number of months primarily for
birding both with and without a 2x barlow (Televue's ). The field and eye
relief are as advertised and unlike the Panoptics exhibit no pin cushion
distortion that can be seen on straight edges. Edge is almost as good as
center with very little loss of either contrast or resolution. The price you
pay is one of size and weight- very big and very heavy -13 oz. The small
amount of sky work I have done with it duplicates the above. If you don't
mind the size and cost they are well worth owning.
Earle Kapchuk
Darwin Bagley
Yes.
>> Does it really
>> have a 65-degree apparent field?
Seems to.
>> 20mm eye relief?
Definitely -- maybe more.
>> Does it suffer any
>> loss of image sharpness at the edges?
Not that I could see.
>> Has anyone used it with a Barlow?
>> If so, which one(s)? Thanks.
Yes, Klee and 2X Televue and 3X Televue. The XL's held up barlowed as
well as the Naglers. But at those kinds of magnification, seeing was
always a serious interference and dimming of the object is taking place;
so, it is hard to tell if 'perfection' is being achieved.
>
I have the 5.2mm, 7mm, and 10.5mm Pentax XL's. I really like them.
In the past when I have said that I am pleased, some have written and
told me to get Naglers instead. Well, I have a 4.8mm and 7mm Nagler, and
I am thinking about getting a 9mm Nagler.
Why do I also want a 9mm Nagler? Well, I have a 6 inch f/15 scope and a
jump from 7mm to 10.5mm is a noticable jump in that scope.
I used these XL and Nagler eyepieces a lot in the Televue Ranger that I
had. I prefer the Pentax XL's over the Naglers. Most gurus would want
to descend from Olympus and strike me dead with such a statement; the
Naglers have a long and well established reputation. But, I have a
reason for preferring the Pentax XL's.
I have very long eyelashes - 10mm to 12mm. With the 4.8 Nagler, I would
have to wash the eyelash oil off every 15 minutes losing any dark
adaptation I might be getting. The 7mm Nagler would require cleaning
every hour. I have never cleaned my Pentax XL's. So, you tell me, which
eyepiece set is a better value for me personally?
I keep the 7mm Nagler because it is a match made in heaven with my C90
telescope. The moon fills the full 82 degrees with just enough black of
space to provide a contrasty background. A view I like to spring on
unsuspecting victims. The 65 degrees of the 7mm Pentax XL does not show
the whole moon; but, the 7mm Pentax XL is preferred by me when it comes
to any other objects and scopes. In the end, though, they each have a
place in my repertoire.
I keep the 4.8mm Nagler because it is a 'standard' eyepiece; a basis upon
which I can make comparisons if I need to. I had a person ask a question
about it; and, it is nice to have one on hand to drop in so that I can
'know' the answer for myself. However, unless I were to cut my eyelashes
off, I will never really get to see the full 82 degress of this 4.8
eyepiece in one view; there is just not enough eye relief. I have to
move my eye around and pick different parts to look at.
I consider the 5.2mm Pentax XL to be one of the seven engineering feats
of man. To have an image quality that equals a Nagler, and the same
basic (for me anyway) usable field of view as the 4.8 Nagler; and, to get
20mm eye relief in the XL is something that is nothing short of fantastic.
Best of all, I don't have to clean the 5.2mm Pentax XL every 15 minutes.
Darwin Bagley
Darwin Bagley
Gert Gottschalk
teal <teal#remove.this.to.reply#@netcom.com> writes:
>Has anyone used the Pentax SMC XL-Series 5.2mm eyepiece? Does it really
>have a 65-degree apparent field? 20mm eye relief? Does it suffer any
>loss of image sharpness at the edges? Has anyone used it with a Barlow?
>If so, which one(s)? Thanks.
A friend of mine has measured the field with a drift method and found that
all of the Pentax eyepieces have 60deg of field and not the advertised
65deg. But that's OK given the other advantages of those eyepieces
especially for those who wear glasses. (eye relief)
Clear skies,
Gert
Dr. Gert Gottschalk
TU-Berlin Institute for Microelectronics | Yesterday reality ceased to exist,
Sekr. J-13, Jebensstr. 1, D-10623 Berlin | All you're experiencing now is the
Germany Tel.(+4930)-31426704 | sole product of your imagination.
FAX (+4930)-31424597 | G.G.G.
SSqui
>> Most gurus would want
to descend from Olympus and strike me dead with such a statement; the
Naglers have a long and well established reputation.
I got rid of a 4.8mm Nagler when I started using the 5.2XL. The 84 deg
FOV just isn't all that impressive at this focal length and the short eye
relief made it a bear compared to the 20mm in the XL.
-
Stewart Squires
"Islands lie beyond the sun that I shall raise ere day is done" Bilbo's Last Song, J.R.R. Tolkien
Darwin Bagley
Wow, that's quite an endorsement! I'm an eyeglasses wearer and I need
*at
least* 20mm of ER -- I prefer 23-24mm. I've never even considered
getting
a high-power Nagler. First, because I'm just starting out. Second, and
mainly, because with the ER that I need, I'd probably end up seeing more
of the field with the Pentax.
<My experience is that I see more field of view with the 5.2 Pentax than
the 4.8 Nagler.>
Since my scope has a short fl (only about 960 or 980), I need an ocular
that will Barlow well.
<I have heard that some high quality orthoscopics will provide more
contrast on the planets than an XL or a Nagler. A high quality
orthoscopic or plossl may barlow up better in some circumstances; but,
not always -- depends on the scope and the object being viewed. However,
the high quality plossls and orthos are $100 for plossls, and $250 a
piece for orthoscopics -- less money of course for lower quality coatings
and such. And, all of orthos and plossls in the 5mm or 6mm range are
going to only have 40 to 50 degree field of view; and, around 3mm to 7mm
of eye relief from what I have heard.>
Sounds like I've found what I'm looking for.
<The XL's and Naglers might not give the very best views possible in
every circumstance; but, as far as the high power XL's are concerned,
they will give about the most comfortable viewing possible for such high
magnification. The Vixen Lanthanums sold by different Celestron dealers
is a set of eyepieces that all boast a 20mm eye relief. They are less
expensive; however, some have hinted that the quality of the view is not
as sharp nor clear as the view provided by the Pentax XL's, and I don't
believe the field of
view is as large neither. I have never used a Lanthanum, so someone with
more experience will have to jump in if I have made any misrepresentation.
>
<I just know for sure, that I am very pleased with my 5.2mm Pentax XL and
feel that it is a good value for what I got. Darwin Bagley>
Todd Gross
>astronomy not to know whether I should : a) be pleased or b) join the
>ranks of the Meade critics.)
Thanks Gene for the plug! ......... unfortunately, the answer is ....... B)
;)
However, try stopping down the scope to 4" or so, it will likely split
both that way,with an off-axis aperture mask. I can split them both in a 3"
refractor. When skies are even slightly unsteady at your larger aperture, the
stars may blur, the aperture mask will take care of that in a hurry.
>I was also pleased with the the view of Martian topographic features a few
>months ago (also on a night of good seeing) when Mars was much closer to
>earth.
that's good news.
>Fun to use for the moon, too.
>Don't have a Barlow so I can't offer any insight there....but wouldn't
>that result in a lot of "empty magnification"?
on certain scopes..that barlow on the 5.2 is quite useful, such as small low
power refractors. Really superb.
Todd Gross
In article <19970615112...@ladder02.news.aol.com> ss...@aol.com (SSqui) writes:
>From: ss...@aol.com (SSqui)
>Subject: Re: Pentax SMC XL-Series 5.2mm?
>Date: 15 Jun 1997 11:25:32 GMT
>>> Most gurus would want
>to descend from Olympus and strike me dead with such a statement; the
>Naglers have a long and well established reputation.
>I got rid of a 4.8mm Nagler when I started using the 5.2XL. The 84 deg
>FOV just isn't all that impressive at this focal length and the short eye
>relief made it a bear compared to the 20mm in the XL.
>-
>Stewart Squires
also, note..that Stew Squires (last I checked) is able to sell these to y'all
at a nice price
j.r. pierce
mr...@lanl.gov (Eugene Mroz) wrote:
>Nor have I compared these to other eyepieces of similar focal lengths.
>But I haven't noticed any image degradation at the edges. However, in all
>truthfulness, I don't use the 5.2 mm all that often on my Meade LX200 8"
>SCT (f/10). This combination yields a magnification of ~384x and only
>when seeing is excellent does it come out of my eyepiece case. However,
>when that happens, such as earlier this week, I am able to split one of
>the double stars in Lyra and can almost convince myself that I could split
>the other as well.
Huh. I have been able to see both of them (albeit barely) with my C8
and its default 25mm (81X) under mediochre (mag 4 barely visible)
suburban conditions several times. One binary appears to be 'inline'
with the pair, while the other appears to be approximately
perpendicular.
-jrp
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