TV Pronto v SW 120 F5

[NGC 1502]

OK, I can hear someone shouting --- " not fair, little old guy versus brawny young big guy !! "

And you are right, it's not fair, but it was fun, here is what happened last night (Tues 15th Jan).

For those not familiar with the scopes, my TeleVue Pronto is a 70mm aperture, F= 480mm ED refractor, and the borrowed contender is a Skywatcher 120mm aperture, F = 600mm achromat refractor. From now on, I'll call them Pronto and 120.

Now, I'm under no illusions about my Pronto, it's a 20 year old design and all technologies move on, the Pronto was superceded by the TV 76 around 10 years ago. The 120 has been around for a while as well, with various paint jobs and badges. The one I have on loan from a local clubmate is the latest SW colour, black flecked tube and white focuser, lens cell and fixed dew shield.

When I first got into astronomy, The SW would have been greeted with horror, a relatively large achromat with such a short focal length will produce loads of chromatic aberation (or false colour, purple halo around bright objects). I'll refer to it as CA from now. There is of course the longer focal length SW 120, but it's not the one I have on loan.

Onto the comparison. I'll refer to each object viewed, with brief comments, and my own opinion (for what it's worth) as to the winner. The mount I used was my own Astro Tech Alt Az. This mount is great for my Pronto, and just about ok with the heavier SW. I used the same eyepieces with both scopes, but varied which one I used to get similar magnification as best I could. I swapped the tubes around to view the objects, not ideal, as ideally they would be on separate mounts, so I could quickly go from one to the other for a better comparison.

Kemble's Cascade was first up. SW at 18x 4 degree field, Pronto also at 18x 3.8 degree field (different eyepiece). Very nice in both scopes but the SW won, the larger aperture helped here with its greater magnitude penetration.

Pleiades was next. Same mags and field as before, stunning in both scopes, but I felt that the Pronto won, maybe slightly "tighter" stars, but most folk, including myself, would be very happy indeed with either view.

Perseus Double Cluster - SW at 27x 2.4 deg field, Pronto at 26x 2.25 deg. Great in both scopes, winner for me is the SW.

NGC 457 (ET Cluster, Caldwell 13 etc ). Both scopes at 60x, 1 degree field (different EP). Winner was the SW, although the brightest component, Phi Cass, was sharper in the Pronto.

M1 the Crab Nebula, a tough object from my location. Winner by a knockout was the SW. Couldn't find it with the Pronto, aperture wins with the faint stuff.

Tried some double stars, a favourite target of mine as they show up well through Southend's light pollution. Looked at Castor, Rigel, Sigma Orion, Beta Monoceros, Gamma Andromeda, Iota Cancer etc. I won't bore you with the various mags used, but in spite of the SW greater light grasp, the Pronto gave a cleaner split in all cases. With Sigma Orion (a quadruple star) the SW did show the fourth faintest member easily, it's tough to see it in the Pronto. It's not to say that the SW is useless with double stars, far from it, but it's not what it's best at.

M35 M36 M37 & M38 were viewed in succession. 60x 1 deg field in both. These fainter clusters showed up best with the SW. Aperture wins again here.

M42, you guessed it I think - SW wins.

M44 the Beehive had risen to a reasonable elevation by now. i used the same mags as with the Pleiades. Winner for me was the SW.

Of course, who can resist a look at Jupiter, especially with the Great Red Spot due on the meridian at 21.50 hrs. Well now, most of you will guess that the SW showed a prominent purple halo around the gas giant. The Pronto did not, dimmer of course, but a far 'cleaner' view. I used between 80x and 120x in both scopes. The surprise to me was that although the SW had that purple halo, the actual detail visible was very similar, the GRS, although not leaping out at me, was there without doubt in both scopes. I fitted a previously made cardboard aperture stop to the SW, to take it down to 80mm F7.5. This cleaned up the view a lot, much nicer, although no more detail was seen. I'll leave yourself to pick the winner.

And yes, I forgot to look at M31, but I'm willing to bet that the SW would win.

The SW will also be a great 'Comet Catcher' for the hopefully bright ones due this year, shame I have to return it

Hope you enjoyed the "unfair" comparison, I found it great fun.

And of course thanks to my clubmate for the kind loan of the scope (he's also a member here on SGL)

Regards, Ed.

[ollypenrice]

Now, I'm under no illusions about my Pronto, it's a 20 year old design and all technologies move on,

Regards, Ed.

They do indeed. So a rack and pinion focuser that is working perfectly after 20 years has been replaced by a bananskin Crayford that will probably slip from new and have you reaching for a Feathertouch in less than a year. A solidly machined rear focuser assembly is engineered onto the rear of the tube while the new technology pushes into the back and tacks it in place with three screws through oversize holes so that it can be 'collimated' by being wiggled about. A human being and optician can had be had by phoning TV up but prgress has brought us Big Brother in the form of the ghostly and, ironically, Invisible Optical Vision Limited, box shifters to the courts of China. Progress!

C'mon, Im j king of course, and I did enjoy your post! But the TV is just so well made. I now have a Pronto and previously had an even older Pearl River Genesis. They were insanely expensive when new and are now insanely undervalued on the used market. Everyone should own a Pronto. They fetch two to three hundred quid and are just drop dead gorgeous. And to be fair to SW, who would have thought that a superbly competent five inch visual apo could be delivered at their prices. It's good news all round I reckon.

Olly

[NGC 1502]

Thanks Olly

"Bananaskin Crayford "

What I meant by "all technologies move on" was that the Pronto was replaced by the TV 76 with better glass up front, although I've never looked through a TV 76, but have read what people I trust have said. Maybe I should check a TV 76 to be certain of that I suppose, before making that statement..........

Yes, the Pronto's R & P focuser is very nice indeed, silky smooth and not a trace of backlash or wobble.

Regards, Ed.

[Brian Nordstrom]

Hard case this ! , I used to have a Pronto great little scopes ( sold to buy a Tak FS60C ) and your SW's big brother the 150mm f/5 , since sold as well .

I had them both at the same time and from time to time drag the both out for a David and Goalith match up same as what you have done here , great fun , the Pronto on an AT Voyager like you and a CG5 for the 150mm ( good match up ) .

Thanks for the trip down memory lane there Ed , and yes my results were very similar .The best one was the moon at about 7 days old , it was fun to see the little 70mm strutting its stuff here when against over twice the aperture and holding his own very well , great fun and thanks again for your comparo.

Brian.

[ollypenrice]

Hard case this ! , I used to have a Pronto great little scopes ( sold to buy a Tak FS60C ) and your SW's big brother the 150mm f/5 , since sold as well .

I had them both at the same time and from time to time drag the both out for a David and Goalith match up same as what you have done here , great fun , the Pronto on an AT Voyager like you and a CG5 for the 150mm ( good match up ) .

Thanks for the trip down memory lane there Ed , and yes my results were very similar .The best one was the moon at about 7 days old , it was fun to see the little 70mm strutting its stuff here when against over twice the aperture and holding his own very well , great fun and thanks again for your comparo.

Brian.

Brian, what do you think of the FS60 compared with the Pronto? Ive seen the 60 used for imaging twice and control of the blue really wasn't very good at all. It isn't 'apo' as a camera lens. However, used with a Herschel wedge on the sun it was spectaular.

Olly

[Brian Nordstrom]

There must have been a columination issue with the FS60C you used Olly , as mine is totally colour free up to 200x + , the Pronto showed some CA but not really bad but a little CA does not bother me at all , not like some people .

As already said here the build of the Pronto ,especially the focusers and sliding dew shield are 1st class , as good as the Tak .

That 's what I mainly use my FS60C for these days and thats using my Lunt Hershell wedge for solay viewing , this combo gives sweet white light views of the sun as well .

The Pronto was a great scope in all ways and still miss it .( as they say ' everyone must own a Pronto at one time or another ')

Brian.

[Peter Drew]

Brian.

I think Olly was refering to photographic false colour issues rather than visual.