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Now, I'm under no illusions about my Pronto, it's a 20 year old design and all technologies move on, the Pronto was superceded by the TV 76 around 10 years ago.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![:embarassed:]()
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.
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.