Friday, 29 August 2014

Google Cardboard from Chinavasion - Unboxing

As a follow-up to my earlier post:
http://julianh72.blogspot.com.au/2014/08/google-cardboard-very-low-cost-vr.html 

I just got my Google Cardboard https://developers.google.com/cardboard/ kit from Chinavasion https://www.chinavasion.com/china/wholesale/Home_Audio_Video/Video_Glasses/DIY_3D_Google_Cardboard_Glasses_-_Mobile_Phone_Virtual_Reality_3D_Glasses_NFC_Iphone_Android/ – not only is the kit complete with all lenses, magnet and washer, NFC Tag, Velcros, etc, but it came fully pre-assembled with the lenses and other doo-dads already installed – you just need to fold it up and drop the phone in.

Unboxing:


About 1 minute later:


The NFC tag appears to be un-programmed, but that's easily fixed with a free NFC-Writer app such as "NFC Writer by Tagstand" https://play.google.com/store/apps/details?id=com.tagstand.writer&hl=en-GB - just program the NFC Tag to launch "cardboard://v1.0.0" (without the quotes) and it should launch Cardboard app.

The lenses are fine, and it works a treat with my Nexus 4!

Wednesday, 20 August 2014

Quick Review: Pentax XCF 10x50 Binoculars

I've been using a cheap no-brand pair of 10x50 binoculars for some time - both for general daytime terrestrial viewing, and especially for night-time star-gazing use. They're OK (well, actually, they're pretty rubbish!), but I really wanted an affordable pair of reasonable quality 10x50 binoculars. 

Hunting around on the internet, Pentax XCF binoculars seemed to come up over and over, with pretty good reviews. They're listed on many generic discount seller sites, but they're also carried by many more "reputable" optical specialists such as BinTel http://www.bintel.com.au/Binoculars/Pentax-Binoculars/Pentax-XCF-10x50/1656/productview.aspx who are offering them for AU$139. You can get them MUCH cheaper from US retailers, so I dived in and bought myself a pair of 10x50s on eBay, and I have to say I'm absolutely delighted. (They're also available in 8x40, 12x50 and 16x50, but I figured 10x50 was ideal for my needs.)



Warning: Don't confuse the Pentax XCF binoculars with the very common "Pentax Whitetails Unlimited" binoculars that you'll find all over the internet - reviews of the Whitetails suggest that while they may be made in Pentax factories, the Pentax name appears nowhere on the binoculars or packaging, so while they may well be perfectly acceptable for the price, presumably the quality is not in the same league as the branded Pentax XCFs.

The XCFs only cost about 30% more than no-brand 10x50s, but the build-quality and optical quality compared to my previous pair is chalk and cheese! The XCFs are so much brighter and sharper, and also have a much wider field of view (6.5 degrees actual / 65 degrees apparent eyepiece field of view compared to about 4.5 degrees actual / 45 degrees apparent for my old pair). The old binoculars feel like I am looking though a cardboard tube in comparison.

The coatings, lenses and prisms are clearly (pun intended!) far superior to my old binoculars, and it shows in the image quality. Everything is pin-sharp, right across the field of view, and the difference for star-gazing in particular is almost startling - they reveal a significantly wider expanse of night sky, and show much fainter stars and nebulae against the background. They are nicely weighted and balanced, and feel very good in the hand.

I would definitely buy the XCFs again, and I am happy to recommend them to others looking for good quality budget-priced binoculars - they are a great value buy!

Full specifications from the manufacturer's website http://www.us.ricoh-imaging.com/sport-optics/products/XCF_10x50#!product-specs :

The PENTAX XCF series combines outstanding optical performance with exceptional value. Ruggedly styled and providing excellent viewing comfort, the PENTAX XCF series binoculars are as easy to operate as they are to afford. High-quality BaK4 prisms and multi-coated optical elements ensure excellent image quality and light transmission. Soft but durable rubber eyepiece rings can be folded back for the convenience of eyeglass wearers. And a centrally-located, extra large focus wheel affords fast and accurate focusing. Sporting fashionable, black-finish bodies encased in full-body rubber housing, the PENTAX XCF series is ideal for almost any application from casual viewing to serious observation. Available in four different magnifications.

Focusing Range: 30 ft. - infinity
Prism: Porro
Objective Lens Diameter: 50mm
Specifications: 10X
Apparent Field Of View: 65 degrees
Real Field Of View: 6.5 degrees
Field Of View At 1000m: 114m
Coating: Super-multi-coating
Binocular Type: Porro prism, center focusing

Thursday, 14 August 2014

Google Cardboard: Very low-cost VR Headset for your Android phone

Have you heard about Google's "Cardboard" DIY VR (Virtual Reality) Headset? https://developers.google.com/cardboard/


If you have a compatible Android phone, you can build this using the downloadable plans, some cardboard, and a few simple items that you can scrounge or buy cheaply on-line. You can then download the Demo app from the Play Store https://play.google.com/store/apps/details?id=com.google.samples.apps.cardboarddemo&hl=en , or browse the "Chrome Experiments for Cardboard" http://vr.chromeexperiments.com/#/desktop , and start experimenting with VR. You can even have a go at writing your own VR apps using the Cardboard Developers Kit: https://developers.google.com/cardboard/overview

And here's the link to the "Cardboard & VR Developers" Google+ Community: https://plus.google.com/communities/111524380182206513071

And if you're not sure about your ability to cut and fold cardboard accurately (Why?! Did you flunk out of Craft 101 in Kindergarten?!) or to find all of the other bits you need, you can buy a complete kit for AU$7 (+ P&P) from Chinavasion: http://www.chinavasion.com/china/wholesale/Home_Audio_Video/Video_Glasses/DIY_3D_Google_Cardboard_Glasses_-_Mobile_Phone_Virtual_Reality_3D_Glasses_NFC_Iphone_Android/


Very cool!

(I had to create a new "Label" for this post - it didn't really fit any of my previous labels!)

Wednesday, 13 August 2014

codebender: A web-based IDE for Arduino

Up until very recently, I have been using the default IDE for programming my Arduinos, which you can download from the official Arduino site:  http://arduino.cc/en/Main/Software

When I bought my MicroView recently http://julianh72.blogspot.com.au/2014/08/microview-chip-sized-arduino-with-built.html , the MicroView website  pointed me towards codebender https://codebender.cc/



This is terrific - your code is stored and compiled "in the cloud", so you can pick up coding and flashing from any internet-connected computer with a suitable browser (e.g. Chrome of Firefox), there's no need to download and install a large IDE (and all the necessary libraries and drivers) every time you want to work from a new computer (just a one-time installation of a small browser plug-in and drivers), and the environment is updated automatically if there's an update available (e.g. new boards and libraries, etc).

Brilliant! Take a look, if you're into Arduino!

Tuesday, 12 August 2014

A simple Push-To controller for your telescope using an Android phone

I have two telescope mounts - a Celestron SLT Go-To Alt-Az, and a powered EQ2 basic German Equatorial Mount (GEM), which has no computer control capability. However, I have added Push-To capability to my EQ2 using my Android Smartphone, an app called SkEye https://play.google.com/store/apps/details?id=com.lavadip.skeye , and a means of attaching my phone to my telescope.


You are probably familiar with the "planetarium" apps which use your phone's sensors to show the night sky in which ever direction you are facing and pointing your phone. SkEye works like this, except it allows you to use what it calls "Indirect Mode", in which you attach your phone or tablet to the telescope, point the telescope at a target, and then tell the app what you are targeting, so it can build an angular offset into its sky view. The app then uses your device's sensors (compass, accelerometers and gyroscopes) to recognise all movements of the device, and thus the telescope that it is attached to.

What is very clever is that the app allows you to perform multiple alignments, and to re-align as the evening's viewing proceeds. The first alignment will work very well for targets within a few degrees, but when you slew right round the sky, chances are that you could be a few degrees off when you re-point the telescope. This is easily fixed - simply target and align a prominent star or planet in the general vicinity of the target you are seeking, align it (which adds it to your list of alignments, rather than erasing any previous alignments), and you should then have surprisingly accurate alignment and "Push-To" functionality in that region of the sky. In this way, the app then only needs to keep track of small phone / telescope movements over a small area of sky, rather than having to rely on a fully-aligned sky hemisphere. If the app's precision starts to "drift", just do another local alignment, and you're good to go again.

There are two versions of SkEye - a free Basic version and a paid Pro version. I think the Push-To functionality of SkEye is well worth the purchase price, so I have gone for the Pro version - 5-Stars! (Pun intended)

I fix my phone to my telescope using a very cheap "Gorilla Pod" type flexible tripod that I bought on eBay. It grips quite well on its own, but by adding a couple of rubber bands to really grip the legs around the OTA, it is really solid and secure. (It wouldn't seem like such a cheap option if your expensive phone falls of the telescope and smashes on the ground!)

The app developers point out that the phone should be mounted well away from any magnetic materials, to ensure the compass works properly. My OTA is aluminium, so that's not a problem, but the phone holder is mostly plastic, but with a bit of wire in the phone bracket. The compass can detect this when it is very close, but a bit of trial and error revealed that my phone's compass sensor is mounted near the top of the phone, and the app works well if I mount the phone in "landscape" orientation, offset to keep the top of the phone as far as possible from the mounting bracket, as shown in these photos.


You might need a bit of experimentation to find an arrangement that works with your phone and telescope. Other options for securing your phone / tablet could involve permanently fixing a cheap case to your telescope, using rubber bands or Velcro, etc.

Add this to my simple way to achieve a good polar alignment on an equatorial mount http://julianh72.blogspot.com.au/2014/08/handy-tool-for-polar-aligning-your.html and you have a very capable Push-To telescope mount, at next to no cost!


Monday, 11 August 2014

MicroView: Chip-sized Arduino with built-in OLED Display!

I bought myself a MicroView recently - it's a chip-sized Arduino with built-in OLED Display!



Check out the KickStarter campaign here:
https://www.kickstarter.com/projects/1516846343/microview-chip-sized-arduino-with-built-in-oled-di

And here's the "Getting Started" guide:
http://learn.microview.io/

Awesome! Now I've just got to work out what I'm going to do with it!
[/EvilLaugh] [/MadScientist] [/WorldDomination]

Handy tool for polar-aligning your Equatorial Mount telescope (And you've probably got one in your pocket!)

It's your smartphone.

Pretty well all modern smartphones have a compass and inclinometer built-in - all you need is a suitable app to access the data. I use the "Smart Tools" app on an Android phone, but there are numerous similar apps on most smartphone platforms.

Here's how I do it:

Set up the tripod at the desired location. If your tripod doesn't have a spirit level bubble built in, lay your smartphone on the tripod platen, screen facing up, and use the spirit level app to get the platen as horizontal as practical.

Now install the GEM mount and counterweight, and put the scope on the GEM. Use the altitude dial scale to set the altitude of the GEM RA axis to approximately match your latitude, and point the GEM approximately south. Align the telescope tube to be parallel to the GEM RA axis, so that it is pointing approximately at the south celestial pole (where the GEM is pointing).

I now place my phone on top of the tube, screen facing up, and long sides parallel to the tube axis. My phone has a rubberized case back, and my finder-scope mounting bracket stops the phone from sliding off; you may need to do something to hold your phone safely. (An elastic band wrapped around the tube may be good enough.) 

First, I get the altitude of the GEM set more accurately to my latitude using the spirit level / inclinometer app. The app reads to an accuracy of 0.1 degrees, so you should be able to get better than one degree precision pretty easily. 

Next, I get the RA axis pointed to true south, using the compass app. (My compass app works with the phone held at any angle, and includes an automatic adjustment for the deviation between true north and magnetic north, so I don't need to do any mental gymnastics to get a south alignment of better than 1 degree.)

Voila! A visual polar alignment within about 1 degree or better on both axes in a matter of a minute or so.