The Pronto with a selection of Naglers
The Pronto was my first experience of the new wave of grab-n-go refractors. Up til then I had always owned large telescopes and the Pronto was a revelation. I loved its high quality, keep it simple design. I loved, frankly, its chic looks with those “mag wheels” for focuser knobs. I was prepared to look past the fact that for a not-very-APO it was expensive, even used.
Design and Build
The TeleVue Pronto looks exactly like the TV76 which replaced it (both generally and in my living room). That means a well made, compact, but quite heavy OTA finished in cream pebble powder coat, with the excellent old TeleVue chrome-drawtube rack and pinion focuser with “mag’” wheels, sliding black anodised dew-shield and screw-on end cap. Mounting is by the identical three inch black anodised clamshell with a pair of ¼ - 20 threads on the base to fit the TeleVue mounts and a single central one for photo tripods.
It’s a classy looking and solidly made OTA, which came with a nice soft case, which is why people still like them. Personally I think the Pronto and early TV76s look better than the more recent ones with their heavy focusers, satin (instead of chrome) drawtubes and satin rather than gloss anodising.
The old style chrome-drawtube TV focusers look great and are super-smooth.
Optically, though, the Pronto is a very different animal from its successor: different, as in worse. Whereas the TV76 has a 76mm full APO objective, the Pronto is a 70mm achromat. Read that again. No, it’s not a “semi-APO”, it’s an achromat! From what I have read (by a certain person who almost certainly knows), TeleVue used a cheap ED glass in the objective which has little or no effect on correction for chromatic aberration, but did allow them to use the letters “ED” when marketing it!
The Pronto has the same optics as the light weight Ranger. Achromatic the optics may be, but they are very well finished. With a Pronto you at least know which aberrations you are going to get, unlike some cheap APOs.
When I first bought my TV76 I tested it with the Pronto side-by-side. Since the focal length is the same at 480mm (the TV76 is F6.3, the Pronto F6.8), it was easy to do direct comparisons by swapping eyepieces.
I discovered that the newer scope’s extra 6mm of aperture didn’t make a vast amount of difference and that both tiny TeleVues were sharp and well figured and collimated. Both gave nice low to medium power views, including of the Moon. However, the Pronto wasn’t much use above 100x magnification and even at that the Moon showed a strong halo of chromatic aberration in blueberry-and-apple hues. So the Pronto is limited in use as a Lunar and Planetary tool and as a terrestrial telescope by being an achromat. For imagers, the violet bloat on stars would be a major drawback.
However, for casual use and visual deep-sky, there really wasn’t as much difference as you might think. So as a casual grab and go scope the Pronto makes sense – it is well made, mechanically and optically, and works very well. Unfortunately, it is still not all that cheap used.
Testing the two side-by-side made me wonder whether the much more expensive TV76 is really worth it if you will mainly be using it for casual wide-field viewing. The answer is probably not, but that is really a debate that applies to APOs versus achro’s in general and may explain why many people are happy with their colourful and pretty, but optically challenged small semi-APOs from a certain manufacturer. For the use to which they are put, such scopes are perfectly adequate.
I think there is a lot of misunderstanding about what you get from expensive small telescopes. Often a quick low-power peek will show nothing more than a much cheaper, mediocre equivalent. To find the difference you need to use the scope for something critical – high powers or imaging. I’m reminded of the time I picked up my little TV60 APO. The guy selling it, who didn’t own an eyepiece capable of more than about 30x with the TV60, clearly wasn’t impressed with it. I suggested we test it, popped in a 2.5mm Nagler (144x) and set it on Saturn. The guy nearly fell off his stool in amazement. ‘I didn’t know it could do that !!’ he said.
The moral here is that the difference between a Pronto and a TV76, two scopes which appear identical, IS significant. But the difference is also much more subtle than you might expect.
You can pick up a used Pronto for about the price of a Chinese “APO” from one of the more dubious brands (I’m emphatically NOT talking about Sky-Watcher). It’s an interesting choice. The Chinese APO will be shinier to look at and have less chromatic aberration when you look through it. However, with the cheap APO you may find yourself puzzling over curious defects in the image that you can’t quite explain. The cheap APO may be less than sharp on the Moon, with a lot of unfocussed light infusing the shadows, even at low power; stellar images may be a bit large and not quite sparkling. With the Pronto there will none of that: at low to medium powers you will have super crisp, sharp views, whilst at high power there will be a lot of dark purple in the view on bright targets, but at least you’ll know why. Personally, I’d prefer the Pronto.
Cautiously recommended as a classy grab-and-go, but don’t be tempted to pay TV76 money for one – it’s an achromat!