Sunday, June 26, 2016

Enhancing the Nexstar mount

Last time I pulled the whole setup to a nearby playground, I managed to put the OTA, the tripod and every accessories inside a medium sized backpack.  And the Nexstar mount was placed inside another bag.  It's very portable indeed.

The backlash has to be adjusted further for high power imaging. 

For the power, I used 8 AA rechargeable batteries, and it gives ~2400mmAh at around 9.6V, after playing for around two hours, I guess only 50% power was left.

I've tried to fit 3 pieces of 18650 inside the battery compartment last time, and it's even smaller than 8 AA!  So I took the plunge to remove the original battery box and replace it with a 18650 battery box.

With higher quality 18650, say 3400mmAh (measured by myself), now I've 3400mmAh at around 11.1V so it should last even longer.  With my current charger, I could recharge them at once, instead of two times (i.e. four at a time), and it's much more efficient, too.  The cost of the 18650 is similar to AA rechargeable, by similar, I mean the cost of one piece of 18650 is similar to that of the cost of one piece of AA rechargeable!  So, the overall cost is less than a half.

And it's lighter too!

The modification is simple and even reversible, just some very simple soldering work.

Friday, June 24, 2016

20160623 Nam Cheong Playground Planet Imaging Night

I had virtually stopped planetary imaging after the shut down of my home@walnut observation point inside my home.

Tonight, I pulled out my C5 with the Nexstar mount to a nearby playground for planet imaging.  While most people were jogging (I use to jog there too), I took a seat on the grass and started imaging.

I feel like an idiot since I spent long time just to center my targets enough for imaging.  I still remember that I could do imaging with my C8 at f/50 but now I found a hard time using my C5 at f/20!

This is my mobile imaging station.  There is a tiny Gitzo G106 below, and a small projector metal plate to support both my Nexstar and my 10" Teclast Windows 8.1 tablet with a keyboard.  It won't be very stable as expected.

Transferring huge AVI files for imaging processing is slow.  My first target was Jupiter but then the processing of Mars was faster.

1345 (UT), this is stacked without further processing basically.

1347 (UT), this one is aggressively processed but it does not help much, maybe even worse... anyway.

Both taken with my C5 with a Tele Vue 2x barlows.  Without a IR blocker, the image is no good as expected.

Jupiter C5 at prime focus, 1308 (UT):-

With 2x barlows, 1319 (UT):-

Much worse than what I could do previously with a C5, I shall practise more.

Wednesday, June 15, 2016

Potential power source for the Nexstar mount

I had been using 3 pieces of 18650 in parallel to provide power to my Nexstar mount via the external power socket.  The internal AA battery compartment is also used as a backup source.

Last night I tried to pull out the AA battery compartment and I found it easy, it was just fixed there using double side sticky tape.  I tried to fit in my 3 pieces 18650 battery pack there and it has more space than enough, and such a modification is easily reversible too!

It even has enough space for a electrical coupler and thus no soldering required.  I'd love to find/make a replacement battery cover after the modifications.

Monday, June 13, 2016

Counter weight solution notes

Time to DIY something just in case...

The Star Adventurer has a M8 threaded hole, while my self adapted Mark-X has a 3/8" threaded hole on the other side....

I've a compact metal shaft with a 3/8" male thread, and 15mm diameter, no stopping screw or safety mechanism.

Just a note.

Field Power

Years I ago, I have a SLA battery which is powerful but extremely heavy, and then I made a bracket to use it as counter weight.

Later, I used 18650 batteries and it's much lighter.  And it's about as powerful as SLA.

Recently, I used USB power banks and it's even more compact in size, and it's airline portable too!

Problem is that, some USB power banks will stop delivering current, maybe they want some sort of hand shakes between devices.  I found a very old USB power bank which will keep on kicking with any load, and this is great.

The Sky Adventurer was now powered directly via USB, the Nexstar mount is powered via USB to 12V cable, and the GOTO Mark-X is powered via USB to 9V cable.  Very neat and portable!

GOTO Mark-X further modifications

It could be the only mount that I had, and could hold a bigger OTA!

I took the controller out, and modify it a bit to accept center positive power cord, and I could power it via my USB to 9V cable.  The current draw is about the same as it states, less than 200mA.  Funny is that, if you pause the motor, the current draw is maximum.  4X speed does not increase the power drain, too.

So, I also pulled out my Sky Adventurer base to fit them together.  I've used a simple tripod quick release base to match the 1/4" of the Mark-X, and it's a perfect fit.

No more need to use that 410 geared head for this purpose, this is also lighter and more accurate.  If I buy a strong tripod, plus adding a counter weight mechanism, it could take a C8, I believe.

Guess what, I always want a C8 after selling it.  But right now, I don't think I have the time and energy to have one yet, or otherwise, I will buy one immediately.