bobro

Slightly better Flame & Horsehead this time with the modified camera. Still need more subs to reduce noise. Polar alignment is causing trailing so will need to pay more attention to it. I like the blue of Alnitak though. 14 lights @ 6min, 1600ISO.

I suspect the issue is down to the (very confusing) PI GPIO pinout between revisions. If you still have a problem after trying 4.1.0, I suggest asking a question in another part of this forum. Someone is bound to know!

If I don't run the 'Guider' script file before starting Lin_guider I get the same error message about the pulse driver. Are you running the script first? It can be run in Terminal mode to see the output. My Lin_guider version is V4.1.0.

Clear skies above me tonight - a chance to finally test the Canon 1000D with the red filter removed. A good change from my previous attempt at the Rosette Nebula - much fuller image. 12 lights each 8 minutes 1600ISO.

Here is a link to the small mods I made to get Lin_guider to run for me. Note that I know little about Linux or the Raspberry PI, so treat the mod as a bit of a bodge. See the notes file for an explanation. Let me know how it goes. http://guidingfiles.web.fastmail.co.uk/

Looks like you have similar issues to what I found. My workaround was to create a small script to initialise the GPIO pins - run before starting Lin_guider. In addition I modified the program slightly. When I get back from work later today I'll look out the changes I made and let you know adder001. I've found, once running, the program to be very reliable. You're almost there! Bob

Great progress Steve obtaining a guidescope and getting Lin_guider to run. Will the Bosma TCE-200 be used as a guide cam? I don't understand your comment 'ST-4 interface is Arduino'. Is the Arduino the receiver for ST-4 signals and controls the (stepper) motors in the mount? Bob

The ebay link is the correct type of relay board. I'm not sure about using a Zero - what about USB for the camera, USB for wireless dongle / ethernet port to connect to PI? Doesn't look as though Zero has enough ports on board. This page gives info on compiling Lin_guider https://hhastrophoto.wordpress.com/2015/07/23/raspberry-pi-b-for-astro-guiding/ Hope you get it going!

The relay board can be bought at low cost from ebay. Just search for 'Raspberry PI relay board'. Plenty of sellers offer them. Note: a bracket is required to mount the DEC motor on the scope. If you go ahead with the project I can measure up the one I made from aluminium sheet.

Glad you have found the project interesting. Info on the setup, wiring and sample images captured with the setup can be found at http://guiding.web.fastmail.co.uk/ You could start with just the RA motor control to get things going. The RA motor needs a couple of simple mods to its control board as shown. The DEC motor is disconnected from its control board as only the motor is used. The PI GPIO pins used for RA and DEC will depend on the PI version. Pin allocations are set up in a S/W config file before compiling the program. Hope this is useful. Bob

Wow! Thanks for taking the time on this Nige. I can see that spending more time on processing will provide better results and Startools will be looked at over the coming days. Setting myself easier imaging challenges (less gradients) might help too! Looking forward to your next outing posted here for us to see. Bob

Stacking is DSS and processing in GIMP 2.9.5. I try and eliminate a gradient by making a grey copy of the image, removing hlghlights, blurring and subtracting from the original. This can produce edge effects, but they can be reduced by making the canvas slightly larger during blurring (takes time so didn't do it for the above image). Basic setup I know and every step is part of the learning process. I used the lens last night as the wind would have disturbed the scope, but the gradient in the wide angle view was big (presumably due to the poor seeing?) - would have been much less with the scope. The lens and camera mod are new to me, and there aren't a lot of clear skies at the moment to test them out and become familiar!

Thanks for the images Nige. I'm amazed that you managed to create such great end results. I captured 18 lights - 4 minutes each at 200ISO, F4, with a 135mm lens. Plus flats. Most likely it's down to my lack of processing skills, but there was a strong gradient due to the vertical orientation of the camera and trying to eliminate the gradient didn't seem to do a lot for the underlying image. Perhaps more/shorter exposures at a higher ISO would have been better? First image below is a jpeg version of a raw, 2nd my attempt at processing. Comments welcome.

Impressive stuff! I tried the same evening to test out my just modified camera with a 'new' 135mm lens. As you say, the conditions were poor - but my images were worse! Could you post a jpeg unaltered version of a single Horsehead image so that I can compare? ISO and scope aperture would help too. Many thanks Bob

Good! If you go for it, M42 should provide nice bright images to put through DSS and then process with GIMP v2.9.5.

Forgot to mention that I hadn't heard about the astro extension to GIMP so I'll check it out. One thing about GIMP that is important is to use a v2.9.x version as this supports 16 & 32 bit images - essential for astrophotography. This allows DSS to save a 16bit TIFF file which can be opened directly by GIMP, so preserving the detail in images that very frequently needs to be stretched. The v2.8 version is only 8 bit and won't produce such good results.

It's the f# (focal length/aperture) that determines how much light falls on the sensor, not just the focal length. The sensor size plays a big part on the final guiding field of view e.g. the final guiding field of view of my setup is actually less than my main scope due to the sensor size being small. The guidescope and guide camera act together so you can't comment on results only knowing one of them. To compare with a cheap 70/400 scope as a guidescope, that would be f5.7 and would give a final field of view of almost 1/3 of my current setup when used with a Cinema webcam. This narrower field of view together with a higher f# could make finding a suitable guide star tricky. One other reason I went for the Orion guidescope was weight - my setup is pushing the boundaries of weight, so I tried to keep it down as much as possible. Your image of the Flame Nebula is rather dark - it could take a much longer exposure, which would give more detail. Below is a single unaltered image of 2minutes 1600ISO with my setup. Even this image could do with a longer exposure to enhance the detail. The M42 image seems to have a stacking issue. The image is also rather dark - perhaps DSS couldn't align it due to this, though it would be better to see a few unaltered images. M42 is very bright and should produce a good image with 30-40 second exposure. Guiding isn't required for this. I suggest ignoring noise and filters for now - just aim for good single images and the rest will come with practice. Longer exposures look to be required. The grey background will be reduced in processing. What exposure time and ISO were used for your images?

Hi Steve, Yes, the guidescope can be an expensive purchase. I considered using a low cost refractor but finally decided on the Orion 50mm guidescope as, with a 162mm focal length, it is quite fast at f3.3 and so can produce a bright image for the guide camera. With my setup the guide camera is a modified Microsoft Cinema webcam, which is reasonably sensitive. The combination makes it not too difficult to find a guidestar - I simply rotate the guidescope slightly until a guide star comes into view. The Orion guidescope takes standard eyepieces, so it can also act as a visual pointing aid if the main scope does not have goto. The short 162mm focal length also helps with the wide field of view making it easier to locate a guide star as the webcam has a small sensor, which acts to limit the field of view. Whether a guidescope with a higher f-number will work for you will depend on the sensitivity of your guide camera. I'm luck that skies here (from my back garden) are quite dark - see the single unadjusted 10 minute 1600ISO image below. If your skies are bright try dropping the ISO whilst keeping the exposure as long as possible - that way the image will capture as much detail as possible. I'm a beginning imager and one of my biggest surprises was how much an image improved with flats. DSS and GIMP are my processing software. Processing can greatly reduce unwanted gradients due to light pollution. If you wish to share one of your images I would like to see it. Hope this helps. Bob

Gradient - more like a mountain!

Had the opportunity to test out the Canon 1000D (with the IR filter now removed) plus a newly acquired 135mm lens at the same time. Of course the Moon put in an appearance, but at least it made for a sort of dramatic, if coloured red, image. Just 30 sec subs at 400ISO - no guiding required of course. Surprised me that the Flame Nebula is just visible.

Hi Seb - had a go at evening out your image with GIMP - at half scale. Bob

You may not get a quick response - Pete H's last visit to this site is shown as October.

Great - the more the merrier!

Thought I'd try to see what GIMP can do by putting the marked up image though it to try and remove the gradient to compare against Gradient Exterminator....

Just finished astromoding my Canon 1000D by removing the IR filter - and have scars to prove it! Can't wait for clear skies to try it out - soon I hope!!