Pronto vs. TV76 vs. TV85 vs. SKY90 vs.?

Anyway, I wonder what you all think about the above scopes in
comparison to the Pronto - is there enough of a performance boost to
make an net expense of $700-1300 make any sense?

I have a Pronto and I also use it as a wide field scope that does OK at higher
powers.

I normally use it in conjuction with a DOB of some sort, set em both em, so if
I really want to see detail, I use a scope with some aperture to it.

My thinking is that the Pronto does a good job of doing what it does best, wide
field views at low and moderate magnifications. No need to ask it or a similar
scope to do much more because the aperture is just not there.

(Here comes my usual 2 centsl...)

I consider an 8 inch DOB to be a grab and go scope, definitely a quick setup in
the backyard. Might consider adding something like that to your arsenal. Less
expensive and it will show you more.

jon

I consider an 8 inch DOB to be a grab and go scope, definitely a quick setup
in
the backyard.

I would agree, if it wasn't for the cool-down time. I almost always grab my
TV76 because the XT8 dob requires cool-down to get usable images. The 76 is
always good to go.

Mark
The Catman
^..^

www.geocities.com/mark_rosengarten
Owner/Coordinator of the Neko Ultraportable Solar Observatory
Fun WITH The Sun for Everyone!

Anyway, I wonder what you all think about the above scopes in
comparison to the Pronto - is there enough of a performance boost to
make an net expense of $700-1300 make any sense? The *primary* use of
this scope (or any replacement) is my grab and go wide-field scope.

Maybe to some people the considerable expense is worth the change, but not
for my money and I doubt that you're sold on the idea or you wouldn't be
asking. The Pronto is a very nice scope (I have one), but if you want to
see anything, you could do better. How about a 6" Chinese refractor and a
chromacor? For about $1,500 you have a good performing refractor with
respectable aperture.

Al


"Chris Greene" wrote in message
m...
OK, I have a Pronto which I've truly enjoyed owning and using.
Recently I was all set to buy a TV85 when I was told by Dave Nagler I
wouldn't see that much of a performance pop between it and my Pronto
and would want a 4" to get a good step up. However, the Tak guy at TNI
said the 20mm boost of the Sky90 would be quite noticeable.

While I also have an ST80 and a C8, it seems the Pronto is my goto
scope most of the time. I mostly like looking at stars and the moon
with a little planetary and fuzzies thrown in (but I do have the C8
for aperture). While there is some color on the higher powers, this
Pronto is pretty good in that regard.

Anyway, I wonder what you all think about the above scopes in
comparison to the Pronto - is there enough of a performance boost to
make an net expense of $700-1300 make any sense? The *primary* use of
this scope (or any replacement) is my grab and go wide-field scope.

(Chris Greene) wrote in message om...

OK, I have a Pronto which I've truly enjoyed owning and using.
Recently I was all set to buy a TV85 when I was told by Dave Nagler I
wouldn't see that much of a performance pop between it and my Pronto
and would want a 4" to get a good step up. However, the Tak guy at TNI
said the 20mm boost of the Sky90 would be quite noticeable.
...
Anyway, I wonder what you all think about the above scopes in
comparison to the Pronto - is there enough of a performance boost to
make an net expense of $700-1300 make any sense? The *primary* use of
this scope (or any replacement) is my grab and go wide-field scope.

Boy, is that imponderable! Mostly, I suppose, it depends how much
$1300 means to you. It also depends how much the (rather severe)
chromatic aberration of the Pronto bothers you. You say that it
is OK, but if you put (say) the TV76 side-by-side against your
Pronto at 200X, the difference would be painfully obvious!
I try to avoid doing that, so I won't be tempted to spend more.

If you are serious about wide-field, then I would say no. After
all, all of the scopes listed above have max FOVs equal to or
smaller than the Pronot. But of course you are not -- you cite
the Moon as a primary target for your Pronto, and the Moon
*certainly* is not a wide-field target.

Between the extra aperture and the vastly better color correction,
the TV85 is certainly a big step above the Pronto for lunar and
planetary observing. Not so for wide-field astronomy, where
color correction is nearly irrelevant, and you will be getting
just a 20% increase in aperture. Not quite enough to justify
buying a new scope, as far as I am concerned. My rule of thumb
is that if you are going to make an aperture jump, you should
increase at least 40%, to feel that you are really in a
completely different league.

I recently bought Orion's Astroview 100mm F/6 refractor OTA as
a supplement to or replacement for my Ranger -- which has
identical optics to the Pronto. Despite significantly worse
color correction, the 100mm F/6 has so much more aperture --
twice the light gathering -- that it is really and truly in
a different league, especially for deep-sky observing but
also for planetary and lunar observing. It is also much
cheaper than the Ranger, which has its attractions!

On the other hand, it is also in an entirely different portability
class, more than twice as heavy and much bulkier. Of course, the
Pronto is also much heavier and bulkier than the Ranger. And
portability is more a matter of the mount than the OTA; as long
as your mount can handle the bigger scope, there is little loss
in portability.

- Tony Flanders

Used TeleVue Genesis and Genesis SDFs come up somewhat regularly going for
around $1200 to $1400 for the non-SDF version and about $300 more for the
SDF version. Assuming you sold your Pronto, you'd be out between $500 and
$800 for a significant jump in aperture and color correction without much
loss in terms of field of view. Just a thought ...

wrote in message
...
On 6 Aug 2003 08:33:34 -0700, (Chris Greene)
wrote:

OK, I have a Pronto which I've truly enjoyed owning and using.
Recently I was all set to buy a TV85 when I was told by Dave Nagler I
wouldn't see that much of a performance pop between it and my Pronto
and would want a 4" to get a good step up. However, the Tak guy at TNI
said the 20mm boost of the Sky90 would be quite noticeable.

I had the TV85 and will say it's miles ahead of the Pronto simply
because of it's lack of colour error. But, If I were doing it again,
I'd get the TV76 simply for portability reasons. These scopes are
all "second scopes" anyway, most users will likely have a larger
main scope.
-Rich

I would agree, if it wasn't for the cool-down time. I almost always grab my
TV76 because the XT8 dob requires cool-down to get usable images.

Sort of depends on what you are trying to look at. Lots of things a XT-8 will
show when it is cooling down that are just not possible with a small scope.

jon

Chuck, you make a good point, one that I think makes sense. If I'm
going to get another refractor I might as well make the jump to 4".
BTW, I recentlly tried and returned an Orion 120ST which had great
light gathering aperture and showed a stunning amount of stars
compared to the little Pronto but, I felt, the optics were faulty as I
couldn't get solid focus with any eyepieces and stars looked a little
astigmatic. A real shame as the color wasn't objectionable using the
scope for its intended purpose.

Anyway, while I think the SKY90 is still a possible, I could keep my
Pronto for travel and move to a 4" APO and not really feel like I was
at cross purposes. After all, we always can use another instrument
that fits a particular need, right? ;o)

An earlier post in this thread mentions the Pronto's false color
compared to the TV76. No doubt, if one pushes it it will have more
color as it's only a semi-APO (which to me means it's a
better-than-average achro) but I never push that scope as I use it
more for wide field viewing. I looked at the moon last night though
with a barlowed 20mm TV plossl (meaning 48x in this scope) and the
view was wonderful with little, if any, color on the limb. Using it
on a TelePod makes high power viewing challenging due to difficuties
in tracking an object. I've had no fun with it much above 80x. If I
moved it to my GP that would raise the issue more than it does on the
TelePod.

Also, as Jon and I discussed via email, I think my C8 on its GP mount
which is by my back door is also pretty grab and go. The problem with
any of these larger scopes is the cooldown time. Grab and go to me
means take it outside and start looking.

Thanks for the replies so far!

BTW, I recentlly tried and returned an Orion 120ST which had great
light gathering aperture and showed a stunning amount of stars
compared to the little Pronto but, I felt, the optics were faulty as I
couldn't get solid focus with any eyepieces and stars looked a little
astigmatic.

Any chance a pinched objective was the problem? Historically, many of the
Asian refractors have a threaded ring that is pinching the objective, loosening
up that ring a bit will often improve things a great deal. One theory is that
they do this for shipping purposes.

jon

Aother thought here, if your are still considering a Sky90 believing
what the Tak sales guy said, he really should re-consider the TV85 as
its off-axis performance is far superior to the Tak. One look through
a 9mm Nagler will confirm that.

Steve D. White
TeleVue N. American Rep.


www.televue.com

You know, you're right. I told David I was mostly interested in deep
sky stuff (but I thought I'd also mentioned the moon and double
stars). I live in rural Idaho under pretty dark skies and find the
Pronto remarkably good, all things considered, for deep sky. Makes
sense that the TV85 would outperform the Pronto on the moon,
separation of doubles, and planets . As I recall, what I was asking
was whether the additional 15mm of the 85 would provide much of a
performance pop over the 70mm of the Pronto.

But look, I'm giving serious thought to the NP101 (wider field than
the 102) so I can justify keeping the Pronto for travel!

Anyway, thanks for the clarification, Steve. I love your products and
wouldn't want people to get the wrong impression of my conversation
with Dave last week. BTW, I think a competing scope to the SKY90
(Pronto tube length, 90mm aperture) would be a wonderful thing.

Chris

PS, I also have a C8 and used it just last night but I still like
refractors better and grab the Pronto far more often.


Chris:

[snip]

I thought your post seemed a bit off base so I checked w/ David
Nagler.

It seems all of your questions to him about the performance difference
between the Pronto and the TV-85 were specifically about deep sky
objects. Not once did David and you address planets, double stars or
the Moon.

David and I both agree that there is a LARGE difference between the
Pronto and the TV-85 on the Planets, double stars and also the Moon.
This is due (like other folks have commented) to the better color
correction of the TV-85.

I have 13 telescopes from an 8" SCT to NP-127, etc. I use the TV-85
the most when I am observing for fun... I am taking one to the
Sierra this weekend.

Steve D. White
TeleVue N. American Rep.


www.televue.com

I hope this helps.