Ags

I think it must be somewhere between 3 minutes and 19 seconds. I shot 3 minute sequences tonight but I will also process short better parts of the runs separately to see less time leads to better images.

Assuming 150 mm aperture, what is the maximum length of time one can image Jupiter before motion blur sets in? I vaguely recall it is 3 minutes?

I rather fancy the ES 20 mm 62 degree for my finderscope. But what I most desire at the moment is a Long Perng 90 mm f5.5 lanthanum/FPL51 doublet. I want a bigger refractor that is still viable for travel.

The boy who cried wolf. It might alert again on Saturday for a real issue.

All hail @neil phillips!

I also shot some sequences without the Barlow - also 3.7ms frames, but lower gain.

Trying to get back into planetary imaging - this effort from last night is looking a bit beter than my attempts from earlier in the week. BB 112 Astro tripod > AZ-GTi > C6 > Diagonal > Revelation 2x Barlow > Astronomik L3 IR Cut > ASI 485 MC. SharpCap > AS!3 > Registax > Gimp Best 16% of 10,000 3.7ms frames. Downscaled 12.5%.

My reducer lives in my C6. It only comes out when I want to use it as a photographic reducer in my Zenithstar 66, or if I want to do planetary imaging with the SCT. Visually, the reducer seems to clean up the image, and gives some more options for larger exit pupils, or wider angle eyepieces at lower magnifications.

Have AZ-GTI internals changed? My new one seems slightly heavier. It worked for a quick solar session this lunch, but I am testing the new mount to destruction on Polaris tonight. For some reason Polaris would trigger Alt runaway in a minute or two. I'll be very happy if it tracks for an hour. Maybe I will get a pretty picture out of it too. I haven't updated the firmware yet...

I too have noticed the ZS66 shows reds and oranges very well.

I have seen the greenish tinge too. I think the Ring is one of the best colored DSOs. It sounds like a great site. Great seat too - are you filing a patent?

Not true, I've updated the engine to run off Fake News!

It is very low, not a good decade for Saturn viewing...

I think the original ancient magnitude scale wasn't a measure of brightness, it was a measure of percieved "size".

@Greymouser Please post your thoughts on the moon book - I am still hunting for a good one. I don't (only) want maps, I want stories!

The Mars is fabulous, beautiful resolution with a strong gibbous phase, not an easy combination!

Saturn has been duly observed at 125x, or 0.528 mm exit pupil, using a Speers WALER 4.9 mm with 1.6x extension tube. The ZS66 blows away (not that phrase!) the C6 on Saturn. Clearly visible in the little frac: Cassini Division, the ring passing in front of planet, traces of surface detail, planet's shadow on the rings. I must say I am happier looking through a telescope that I feel is overperforming rather than one that seems to be doing the opposite. Also, absolutely no traces of floaters in the frac - I am sure they were there but indistinguishable from the seeing ripples. Two hacks I am using to boost the refractor's performance: a celestron prism diagonal to reduce the residual CA of the scope (it really does work - on the right scope!) and a Wratten #8 to tame the atmospheric dispersion.

I am hoping to get out again tonight to try 0.5 mm exit pupil on Saturn, I only discovered the very small exit pupils were viable in the refractor when Jupiter was up and Saturn had drifted behind Tower Block C due south of me.

That may help the seeing, but the points about contrast and floaters remain. Definitely looking at picking up a nice 90mm frac 😀... Just the right size for travel and enough to get decent magnification on the planets and splits on doubles.

No, but it is outside cooling for four hours. It is worth trying this however, if I can overcome my aesthetic objections! I forgot to mention I was also observing with a GSO Wratten #8 filter last night, it certainly helped a lot with atmospheric dispersion.

I had a good long look at Jupiter and Saturn last night with my Zenithstar 66, and the difference to the past few nights of observing with my C6 was quite striking. Firstly seeing seemed much more stable with the ZS66, a well known effect of small apertures. I will need to prove this with a side-by-side comparison of the two scopes on another clear night. Secondly the contrast and color was much stronger in the refractor. For example, the SEB is faint in the C6 but plain as day in the ZS66. The GRS was visible last night but I think the smaller scale in the refractor worked against it. Thirdly I'm not sure the C6 has revealed much more detail. On Saturn, the ZS66 seemed to show better definition of the rings including shadows on the rings. I guess on a night of excellent seeing the C6 would pull ahead, but I don't exactly live on a mountain-top. Finally, even when I pushed magnification to 0.5 mm exit pupil, floaters were less of an issue in the refractor than the C6. I wonder if this comes down to what photographers call bokeh - the smoothness of out of focus objects. Mirror lenses for cameras are plagued by very rough and intrusive bokeh because of their central obstruction while a good refractive camera lens can have much smoother bokeh. So maybe what troubles me with the C6 isn't just the floaters but the noisy bokeh of the floaters? I won't get rid of my C6 - it excels at deep sky and some kinds of doubles - but I am definitely saving up for a bigger refractor.

Beautiful!

Earth is a generation ship trapped in the Sun's gravitational well...

Thanks - the book should be ready by Christmas 🤣