20180728 Mars Opposition + Total Lunar Eclipse

Mars Opposition could be observed for a period of time, say a week or even a whole month.

Therefore, the total lunar eclipse was the prime target earlier this morning, it's the longest total lunar eclipse for the century.  I came home after working and slept nearly immediately to prepare myself to wake up for this event.

The sky was not promising, one word says it all: misty.  When I woke up after less than two hour of sleep, it didn't improve a bit... luckily, the moon and the bright Mars were still visible through the mist or thin cloud.

Encouraged, I pulled out my 85ED and mounted it on my Nexstar mount, in the hope to capture some high power shots with my ASI 120mc.

Took two clips but none of them was stackable, so I posted the raw video as below.  The exposure and gain were both very high, yielding very low frame rate:

Since the mount was occupied, I took this with a Canon 100-400mm hand-held using spot metering, 0246 (GMT+8):

And then a wide field shot, 0248 (GMT+8):

Manual exposure was used to keep the exposure fast enough not to overexpose the lunar disc too much.

And then this one at 0318 (GMT+8):-

And a quick closer up 0323 (GMT+8), to show the red hue:-

And then things got worse, I have to use GOTO to the moon!  Can you see the moon in this shot?  I　am sure not!  The shot below also told you how close the moon to a nearby new building.

But you know, when there's nothing, there's really nothing there!  I pulled out my 10x30 and checked with my eyes, nothing.  5 seconds exposure?  nothing.

When you were about the give up, I realized that I could just close the window and sit in an air conditioned room to wait, so why not?  After some wait and hey... was it a cloud or what?  no, it's the moon!  taken at 0409 (GMT+8) 

The Mars was way brighter than the moon by then, not unexpected, right?

04:22 (GMT+8), probably the best eclipse shot of the night, stars could be seen around the moon, clearest moment of the night.  I could imagine such a totality would be wonderful under a dark cloudless night!  But hey, we could only imagine as a Hong Kong observer!

04:25 (GMT+8), and the Canon 100-400mm got the mount now, I checked the EXIF and it was at 200mm, a zoom lens could be nice for this purpose, you could frame your shot the way you liked:-

And a shorter exposure one at 0426 (GMT+8):-

I tried to get a close up but it was shaky, since the cloud was getting thick resulting in longer exposure.  The cloud window was closed.

Alright, time to sleep.  Luckily, it was Saturday in the next morning so I could sleep longer to make up the observation time.

Finally, a few slash back shots:

First up were two mobile phone shots while going home, before the eclipse:

This shot with a historical building in the front, should be taken as layers and merged back, but I got no time to do so.

Equipment shots, of course, taken during cloud cover, just a record.  The new ES diagonal is nice.

And finally, the Canon 100-400mm lens on the Nexstar:

Sorry that I (very rarely these years) bought new equipment these weeks, and still got some in transit, weather curse applied.

A short summary in Chinese: 香港天文，注定有雲 (Hong Kong astronomy, cloudy astronomy)

85ED refractor DIY electric focuser

This is the third generation.

I have remounted the motor to a acrylic plate:

And then stick it to the metal mounting plate.  The metal mounting plate is then attached to the focuser via existing screw holes.  I have bought two M3 thumbscrew for easy attachment, and for easy disengagement... Rubber rings should be added for rapid disengagement.

The above black set screw might intervene the meshing and thus I have pulled out the gear on the focus shaft a bit like below:

Initial testing:

Disengaging the motor is not very easy right now, I have to figure out way to solve it.  Hopefully a few rubber rings below the thumb screws should do the job.

The internal of the 85ED

Take an image from the focuser:

Not bad I would say.

The circular pattern belongs to the focuser, and the OTA is the black lined cloth/paper like that of the Ranger: light weight, simple and effective as you could see from above.

First Impression: Explore Scientific 2" Carbon Fibre Diagonal

Hey, I got a new diagonal.

Over the year, I have a couple of diagonals and the one which is always with me, is a 1.25" Tele Vue mirror diagonal which comes with my Ranger 20 years ago!

My first diagonal was a 1.25" hybrid mirror diagonal from my C90, it converts 0.965" into 1.25" which is essential.  I have no way and no experience to judge its performance.

My second one is that Tele Vue, top quality I would say.  Then I bought a 2" Antares diagonal for my SCT and that's what I love, too.  I owned a Zhi tong 2" mirror diagonal, too.  It's cheap but with similar performance with the 2" Antares!  I also owned a 1.25" Astrotech diagonal briefly, this is a dielectric model which has high reflexivity... I don't find it much better than my Tele Vue so I sell it quickly.

After that my astronomy time shrinks, and that Tele Vue aged over time.  I don't find any performance drop, since it's a so slow process.  But mentally I know it's aged.  And now since I transformed my Ranger into 2" focuser, and my new 85ED has a 2.5" focuser, so I ordered a new one which is an Explore Scientific.

The first impression is that it comes with a huge box!

That so-call carbon fibre was only on the two side, not much help with weight saving nor performance about temperature changes.  It's somewhat stylish, however.

The bottom has four screws which must be for collimation, and I believe no one would want to touch them!

I shall see if it helps on imaging... I know a diagonal must be taken away for imaging, but for the sake of convenience, I always use a diagonal for solar system imaging.  I also want to go back to 2" eyepiece for visual scanning which is my prime interest in visual astronomy!

My particular sample has missed the protective ring in the 2" interface and the seller agreed to send me one later:

It would be nice if the 1.25" adapter is recessed into the 2" interface to save some back focus.  My 1.25" 20mm widescan can just reach focus with this diagonal... less than 1cm remains.

20180721 Moon and Jupiter

There is a thick mist with low transparency, seeing moderate.

85ED with 5x Powermate, first time taking moon shot with this scope, I expect better result with better sky.

1312 (UT):-

,

1314 (UT):-

1416 (UT):-

And without removing the monochromatic ASI 120mm, I turned to Jupiter:

Taken at 1322 (UT), 5x Powermate, Drizzle 1.5x

20180716 Mars

I woke up again in the mid-night to take these, again it's 20180717 in terms of local time (GMT+8), but then the title above is in UT.

Manual focusing was used, I've installed the Rigel Quick Finder on the 85ED and alignment was a breeze.

2004 (UT), 85mm ED f/6 with 5x Powermate

2011 (UT), 85mm ED f/6 with 5x Powermate stacked with 2x

Similar level of detail, but Mars is so bright that is tempting for bigger image scale.

20180716 Jupiter, experimental stacking of 5x and 2x

It is a very windy day, a typhoon will be passing by soon.  Expect very poor seeing but then it's rather decent at 6-7/10, nearly the best I can ever experience at home!  Transparency like 6/10, it's a very good night for me.

As usual, I used a 5x Powermate to capture two shots, drizzle is not used:

1304 (UT):-

1307 (UT):-

I didn't use my motorized focuser yet, because it's still being fine tuned.  Manual focusing is do-able with some more patience... the second shot was taken in attempt to improve the focus, but it seems similar.

Encouraged by the visual testing this afternoon, I pushed the 85ED again by inserting a 2x barlows after the 5x, which means f/60 at least, I estimate it to be f/66.7

1313 (UT):-

No more detail can be obtained over f/30 with the 5x Powermate alone.  Just an equipment test.

Magnification limit of the 85ED

This is a small aperture, short focus refractor... but with the help of the FCD1, let's see how much we might push it.

The test is conducted during day time with distant objects.

First up is a 20mm eyepiece, so we have 510/25 = 25.5x, image is exceptionally sharp.

And then I inserted a 5x Powermate, and it yields 128x, image remains very sharp.

Replacing it with a 4x TMB, i.e. same magnification as about, this eyepiece is sharper.

My floaters come in... I got a couple of annoying floating within this year, I'm getting old.

Insert a 2x barlows, we have 255x and image is still very sharp, but of course, it's getting dim with only 0.33mm exit pupil.

I don't expect to be able to see anything, I used a combination of 5x with the 4mm TMB... which means 638x!!!  Crazy me... I racked the focuser in and out, finally got a sharp but very dim image at 0.13mm exit pupil!

No image break-down!

With the Ranger, such a magnification was spoiled completely by the chromatic aberration.

20180711 Mars

It's 20180712 already in terms of local time, but the title is in UT.


Other than the world cup, woke up for the first shot of Mars for this apparition... really dusty!

2102 (UT)

Manual focusing was used as the electric focuser is under revamp, it's still doable with some patience.
85mm ED with 5x Powermate, 1.5x Drizzle as usual.

20180711 Jupiter as a test of the DIY electric focuser

Made a quick and dirty first version:

Still need to find better way to mount the motor so that it could be fixed along the OTA direction.

Anyway, it works.

We got 0.1/10 transparency, the Jupiter was a fuzzy patch of light with naked eyes.  I've to push the gain to maximum, and shutter to something like 0.3-0.5 second to get a very dim image. 

Manual focusing is impossible under this situation and it also proves that the electric focuser indeed worked.

1409 (UT), and I got only 200 frames due to the long exposure required for each exposure, and thus a very low frame rate.  Anyway, it is just to test the focuser.

My new 85ED refractor

It has been a long time since I bought a brand new telescope.

My brand new telescopes include my first scope Celestron C90, and then a Tele Vue Ranger.  Later a C8 and then everything else was second hand, including a Takahashi Sky90, a couple of C5, ETX 60, PST, a 5 inch Maksutov, etc.

This time I got a 85mm ED refractor.  The Tele Vue Ranger is really out dated in terms of its lens, don't get me wrong, it's a perfect achromatic refractor but that's all.  For H-alpha solar observation, it still performs exceptionally well because it's well figured.  For monochromatic light, it's unbeatable even compare with modern day FPL-51 or even FPL-53 based refractors!

Okay, let's go straight to this little new guy:

The core is its objective, it's a 85mm lens at f/6 with focal length of 510mm.  Very close to my Ranger which is 480mm.  This guy is actually a bit faster.  At f/6, even a FPL-53 based refractor would be hard to be a real apochromatic, not to say this is just a FCD1 based (similar to FPL-51) one.  This scope was advertised to have FCD1 matched with H-TF3L, but whether H-TF3L is special enough apart from a simple flint, I don't know.

The scope looks very nice.  It comes with a rack and pinion focuser, with dual speed knobs.  Focusing is smooth.  It's a 2.5" focuser and it comes with 2" and 1.25" adapter with compression ring.   The focuser is rotatable.

The tube rings are very nicely machined.  The including dovetail is a bit too short, I've replaced it with my Intes and it's just about right length for better balancing.

And worst yet, the original dovetail is too short to fit in my Nexstar mount.  Even a long camera tripod balance plate works better, as shown below.  Notice that if the dovetail is shorter than the clamp saddle, it simply won't fit in:

I've checked the tube and there is no light baffle inside, just like the Ranger with dull black sand finish, not bad and it keep its weight low.

The paint job is not very good, there are some missing paints here and there.

The dew shield is retractable, so that at its minimum, and it's about the length of my Ranger.  Very portable indeed, and I've enough room inside my dry box.  Of course, this guy is heavier, nearly 1.5X of the Ranger.

And the tube rings:-

with the Intes dovetail, the original one should be lighter.

I've removed the left focusing knob and replaced it with a brass gear, and I handheld a small DC geared motor there and they mesh well.  I shall make mounting hardware for it asap.  I deadly want motorized focusing as always.

Enough modification for the first day, em?

Guess what, I'm lucky enough to take a test shot with Jupiter during the first night!  It's less than 3 hours after its arrival.  Seeing was very poor but then at least I can tell, the chromatic aberration is far better than my Ranger, at half the cost twenty years ago!  When inflation is taken into account, I get a very nice deal indeed!  I hope this is going to be my work horse for planet and general observations.

I will keep my Ranger solely for solar works, and I believe the Ranger might still be better than this new refractor in terms of monochromatic solar imaging.

Due to the fact that I already had my Canon FD 300mm f2.8, it makes not much sense for my to buy the field flattener for this scope.  The next step might be a 2" diagonal plus a 2" wide field eyepiece, but then I shall be using my Canon 18x50 instead?  Let's wait and see, there's no need to rush.

Maybe motorizing the focuser and attaching a Rigel Quick Finder are among the first priority.