[astro744]

All this talk about how large a telescope and magnification you need to see bands and the Great Red Spot on Jupiter got me thinking and I thought what better to use to test this than my Tele Vue 60 refractor. OK not quite a 76mm short Newtonian but it will do.

I was up a bit earlier than normal this morning and noticed the GRS on Jupiter was to transit at 5:47am. I need to be at work by 6:30am and since it was only about 5:25 I decided to go and have a look. It takes all of three minutes to go from taking my Tele Pod out, mounting the 'scope and having an eyepiece in it pointing at Jupiter. It takes only the time it takes to boil a jug and make myself a cuppa for both the eyepiece and telescope to cool down.

It was a bit windy this morning and there was a bit of cloud but it was clear all around Jupiter. The waning Moon was completely covered by cloud and I only realised it was up when I got into my car to go to work. During this time Jupiter was not covered by cloud once. In these conditions I wasn’t expecting the seeing to be great and when I first setup and switched to the 6mm setting on the Tele Vue 6-3mm Nagler zoom I saw Jupiter a bit mushy a sight I was not accustomed to in my little refractor expecting it to be sharp almost instantly and I put this down to seeing and almost zero cool down time when I first looked this morning. Within only 2-3 minutes it had improved dramatically and I was able to up the power and at each stage of the zoom I noticed what I could and could not see. I was using a Tele Vue 60 deg. diagonal and seated low on an adjustable astronomy chair.

6mm setting is 60x
5mm setting is 72x
4mm setting is 90x
3mm setting is 120x

At 60x the NEB & SEB were easy and the GRS was a little 'pimple' to the right of the south equatorial dark band, (SEB). East was up and North was left. The north polar region was a grey colour with no distinct band. The best way to describe Jupiter's two main dark bands (NEB & SEB belts) is like a 'seam on a cricket ball'.

At 72x the NEB & SEB were easy and the GRS was a little larger 'pimple' to the right of the south dark band. The north polar region was a grey colour with no distinct band. The south polar region was brighter than the north and had a hint of a thin band.

At 90x the NEB & SEB were easy and the GRS was a little larger again starting to appear like a small oval to the right of the south dark band. The north polar region was a grey colour with no distinct band but a hint of variation in it. The south polar band was a little easier but still required moments of better seeing. The two equatorial bands started to give an ever so slightly uneven appearance.

At 120x the bands were easy and the GRS was a little larger again but not as contrasty as at 90x. The two equatorial bands were definitely uneven in appearance with what was possibly festoons just coming into view but not distinctly or at least the uneven edge of the belt and the north polar region had a hint of a very thin band but it was rare. The south polar region had a definite band there.

I then added a Tele Vue Planetary filter to the same eyepiece and the overall contrast increased significantly but the greatest thing about this filter is the colour it gives to the GRS. I call this the Red Spot filter as it gives a saturation boost to the colour of the Spot without making the whole planet red. It is a fantastic filter! (now discontinued unfortunately).

The boost in red with this filter is greater at larger apertures and when I first used this filter on a 6" f8 Newtonian on the GRS I just couldn't believe how red it made the spot without affecting the colour of the rest of the planet to the same extent. The colour boost on the TV-60 was not as great as on the 6" f8 Newtonian but was there nonetheless.

I then wanted to test how small an image I can get before the banding is not visible. I tried the 16mm T5 Nagler (22.5x)and there was a hint of darker appearance in the equatorial region but I just couldn't get a steady image that seemed to blur more frequently with seeing. It is a very small image at 22.5x even for Jupiter.

I then tried a 9mm T6 Nagler (40x) with and without the Planetary filter. In fact this time the GRS was slightly easier without filter but it was only there in moments of good seeing and was very tiny and if I had not known that it was there I may not have identified it at this power. The two equatorial bands were easy at this power and the north polar region was more grey and less bright than the south polar region.

I then tried a 7mm T6 Nagler (51x) with and without the Planetary filter. The GRS was small but just visible with and without filter but again it was only there in moments of good seeing and was very tiny and if I had not know that it was there I may not have identified it at this power. The two equatorial bands were easy at this power and the north polar region was more grey and less bright than the south polar region. The image was noticeably larger than at 40x. In fact each 10x power jump makes for a noticeable and significant image size jump. Especially between 40x, 51x, 60x, 72x.

I was running out of time this morning but wanted to quickly try two other eyepieces, 8mm Clave and 8mm Brandon (45x). I could not use the filter on either as the Clave was not threaded and the Brandon had its own proprietary thread and I did not have the adapter. Both gave a lovely contrasty image and comparable to the Naglers but I was not comparing eyepieces here merely seeing what I could see on Jupiter at a given magnification and at 45x the equatorial bands are easy as is the colour/brightness difference between the north and south polar regions. The GRS was a 'pimple' to the right of the SEB. In case you're wondering I preferred the view in the Clave over the Brandon at least this morning on Jupiter. The warmer tone of the Clave does wonders for Jupiter! The Nagler T6 views were just as nice though but since there is no 8mm T6 Nagler it is unfair to compare against a different eyepiece.

I know you cannot compare a Tele Vue 60 with quality eyepieces to a 76mm 'store' telescope and 'store' eyepieces but I felt it important to make it known that a small aperture instrument operating at low powers is sufficient to see bands and the GRS on Jupiter. With the GRS though make sure you know when it is next on the central meridian and then give it a go. If you don’t have the Tele Vue Planetary filter, try a light blue 80A. It wont be red but the contrast boost on the spot could be is just enough to make it 'pop' out. (I have an 80A filter somewhere so I'll try it too next time with the TV-60).

Note though with a Newtonian it must be collimated or what you see will suffer and this could be significant if instrument is considerably misaligned.

Hope you enjoyed the rather lengthy report. Since getting the Tele Vue 60, I have found I use this telescope the most out of all I have especially for quick planetary viewing. The setup is almost instant and the views are exceptional. For extended planetary viewing I either use another telescope on a driven mount or piggyback the TV-60 and use it. It is just a little too light to use alone on my GM-8 although I haven't tried without any counterweight yet. Having a driven mount allows for greater detailed and concentrated study as you are not distracted by a moving image and constantly having to nudge the telescope.

Hope you enjoy your astronomical journey for many years to come!