Thanks Duncan - at the moment I'm limited to between 5 and 10 second subs without any drift alignment it seems. Frustrating to say the least. I eventually will get a reticular eyepiece and will learn drift alignment to get better subs, I know it's the best way of approaching this, I'm just trying to hack things "as is" for the moment! Thanks for the encouragement.
*snip*
Dave
Dave, if you dont drift align, then you can get very good aligment with a compass, an inclinometre, and some info of the net.
I dont drift align, my mount was setup using the above equipment, and i can do exposures over 30 mins without trailing.
Yes.
And as I mentioned before, you can align even better with build-in polar finder (just make sure it is properly adjusted, this can be done during the day on a distant tree, for example - adjust the reticle until the central cross is placed at the detail which does not move as you rotate the shaft).
I placed three concrete slabs (10x10cm) in the loan, with shallow holes for tripod legs.
This way, I do not have to align every time I go out, once in a week is good enough (provided I do not dismantle the tripod after session, of course).
Of course, drift alignment will give you better results, but it takes time, which is sometimes valuable...
The problem is the land that my parents house is on - from the backyard I have no views of the South, and none of the East. Limited of the West. North is pretty much OK. Positioning the scope on the East/West of the property doesn't help. That leaves setting up the scope on the front section of the property. As the front is shallow, and steep, and as either trees or houses block views to the east/west (although not as bad as from the backyard), I'm limited to a very small area to place the scope and get some semblance of view. Sadly, the best place is not on our property, but just off it, on council property. So I can't set up anything permanently there. I can move the scope/tripod 2 metres back from this semi ideal spot, but alas, I start to lose views to the east/west (north/south are still OK). It's a really bad situation and I can't do much with it. It pretty much kills a permanent mount setup imho.
I do need to get a inclinometer and I have measured due South due to solar noon. It's no longer marked, but I could probably permanently mark it somehow. I know I need to get longer subs.
Of course, I'm not even to the point of guiding yet, but that, also, will come in the future.
I think the first step is to get an electronic inclinometer and work on getting due south better. And also a reticular eyepiece and get drift alignment going. Then I should be able to get 5 min subs at least!
Bojan - I'm not sure what you mean by aligning with the built in polar finder during the day. How can I do that when the stars won't be visible to align against, or am I completely misunderstanding you?
Bojan - I'm not sure what you mean by aligning with the built in polar finder during the day. How can I do that when the stars won't be visible to align against, or am I completely misunderstanding you?
Dave
The problem is, polar scope is usually not aligned at the factory (that was my case as well).
What I did was, I pointed the polar shaft of my EQ6 mount to a distant roof (20-30 metres away) , so that the top was near the centre of the FOV of the polar scope.
Then, by rotating the shaft by 90 degrees back and forth, and adjusting it left-right and up-down, I directed the axis exactly on the top point of that roof.
The next step was to adjust the cross of the reticle to coincide with that point of the roof.
If you are doing this you have to be careful with reticle, it is easily damaged if the grab screws are tightened too much. Also, there are three screws - not very convenient for adjustment (it would have been much better if there were 4) but it is possible to do, and it has to be done only once.
Then you can use polar scope when you are away from home, it is pretty accurate - I do not have problem at all with 1 minute exposures. The bigger problem will be periodic error in the main worm gear.
For the compass, I mounted it on the 0.5m long Al rod, which can be screwed onto and removed easily from the mount RA shaft . For Melbourne, the difference between true South (North) direction and what needle is showing is 11 degrees to the west, so this has to be taken into account. Once adjusted, you leave compass alone on that rod for the next session
And of course, you should make use of the build-in bubble level (it comes with newer mounts, if yours does not have one, you should definitely place it on the RA shaft, and it should be adjustable. you should null it when you have RA shaft pointed exactly (or near enough) at SCP.
This way, you have to align your mount only once. Next time only bubble level and compass are enough, even if you go somewhere out of the city.
However, if you go couple of hundred kilometres to the South or North from your home, you should check the elevation or RA shaft, the difference in elevation will abe significant and quite visible in the polar finder (and on your photographs as well)
Thanks for the explanation, much appreciated. I'll have to look at the polar scope during the daytime - many have said not to bother with it because of the lack of a bright star around the South celestial pole. I like your idea with the compass on a long shaft - that's brilliant. I think most of my problem is probably due to innacurate latitude adjustments. An inclinometer will resolve that problem.
I'm gradually getting things together - at the moment and for the next Six months, my main goal is a car. After that, I'll do some stuff with the astro gear
My goal is to to learn drift aligning, get accurate polar align, 5 min subs and guiding going. After that, it's mastering darks, flats, lights etc. And after that, PP. I'm not worried if it takes me a few years, or even if I don't master it all, as long as I'm having fun, that's all that matters. And despite a rought early start with imaging, I'm having fun!
It's a hard slog, but, keep at it. You'll often wonder why you bother. Then, you'll start dozing off at work daydreaming about the next time you get a chance to image and what you will be imaging and what the weather will be like and whether your equipment will conspire against you, etc. This is one nasty and obsessive hobby!
Sorry to butt in, didn't want to start a new thread.
When I stack an image in DSS and choose to Autosave the resulting file, it is in a 32bit HDR file. How do I save a normal 16bit file?
Sorry to butt in, didn't want to start a new thread.
When I stack an image in DSS and choose to Autosave the resulting file, it is in a 32bit HDR file. How do I save a normal 16bit file?
Click "Save Picture to file" then choose 16-bit tiff.
OK, having read the thread from top to bottom I'll stay out of the camera suitability debate.
I started with Nikons, went to Canon, and have now settled on Sony. Why? C'os most of my DSLR shots are during the day and I like the Zeiss lenses Sony use. Nothing more or less.
Dave, I reckon you are seriously into self abuse here. The root problem stems from the lack of polar alignment and really you need to sort this. Of the semi-serious astrosnappers on this forum I would venture to suggest only a small amount of the have a set-up which approaches a permanent one, and that includes me. I roll mine in and out each night I use it. The trick is to reduce the effort, I am lazy in this respect. Get yourself an area where you can safely say you will be able to image most or all of the time. Get set up and don't image, POLAR ALIGN. Once it is correct, or better, ensure that you can return to the same spot every time, and simply "plonk it down". In my case I have levelling screws on my rolling pier and these are screwed down each time I use it, (to lift the pier off the wheels). The points of these screws/bolts are tapered and fit into three large stainless steel washers glued to the asphalt surface where I image.
If you need help with polar aligning, get it, there are gazzilions of members who likely live close and would be happy to help you.
Then you will notice the whole things gets easier.
Gary
Yeah, I know Gary, and it's good advice. Once I get a reticular eyepiece, I'm going to work on polar alignment and drift alignment etc. I know it needs working on. And I know that imaging will improve once I get it all down to pat.
Cheers Dave, I was afraid you may have taken offence. But in the end, it starts with alignment, and works outward from there.
See if you can get some help with the polar alignment, and get the marks set out on the ground so the repeatability is there as well. Then start thinking about longer exposures. Get some help from anyone who will assist. If you are really stuck I can even lend you a reticule eyepiece, if that is all that is holding you back.
Gary
no no no no, takes more than that to offend me for starters, and your post wasn't even remotely offensive. It's all good advice and I appreciate it.
Reticule will happen in the next 5 weeks. From there I'm going to work on polar alignment etc. As you said, practice and things will be good. I'm going to be getting an electronic inclinometer as well. Don't worry, it'll happen.
I guess I was hoping I could still do half decent shots in the interim. I can't wait for M42 to come around again, cos I'm pretty sure I'll be able to better my first efforts (3 x 30 second shots stacked in DSS). I'm sure 40 or 50 10 second shots will be a lot better! And this time around, darks and flats as well. Go me.
I'm sure 40 or 50 10 second shots will be a lot better! And this time around, darks and flats as well. Go me.
Dave
Dave
Dave, I do not think more of shorter shots will be much better..
There is no need to take much more than 10-15 shots.. but it helps a lot if they are longer.
As for reticule, why don't you try to improvise something in the meantime?
Actually, you do not need it, your camera with some software (for example, Crosshair.exe by Joe Smith.. or Al's http://www.iceinspace.com.au/forum/s...ad.php?t=21798 crosshair) will be quite adequate, in combination with camera control application which downloads and displays image on the screen ( Focus assist works with Canon, I am not sure if it works with Nikon, http://www.dslrfocus.com/, there was a freeware version available).
There are some methods described elsewhere on IIS, but all of them basically follow drift alignment method: You are taking images of the same star every couple of minutes, with the help of screen crosshair you see where the star is drifting, and you adjust the polar axis up or down, left or right until there is no drift.
When this is done, you simply start imaging.
And, do not forget other advice here, particularly those related to repeatability of your setup.. Someone hammered into the soil three 1/2" waterpipes 15-20cm long , and the EQ mount legs are supposed just to be inserted into those pipes.. repeatability is more than adequate, provided you do not dismantle the tripod.
Ah, spot on Bojan, Dave, try the likes of K3 CCD Tools, and a webcam, it has the Ponder Polar Align Routine built in. And there are others, all of which utilise a webcam instead of the reticule.
If pictures of the "repeatability" side of my setup will help, just ask.
Gary
I found the post with water pipes.. http://www.iceinspace.com.au/forum/s...ad.php?t=35041
As far as my semi-permanent site is concerned, instead of those plastic pads shown on images and/or pipes, now I have concrete slabs (~10cm cubes)
Interesting. Very interesting. You know, I'm tempted to move only as far back as possible and get a permanent pier setup, just far back enough to be on our land and not on council land. Must give it some thought long term wise.
I won't bother with a webcam - initial goal is a 10mm reticule etc, drift align with that, get polar align pretty well spot on or as close as, then image. If I can get 2-3 min subs without star drift, and not having to guide, so much the better. Guiding will come later on down the track. Still thinking about getting an of axis guider, or separate guide scope/autoguider (leaning towards the latter).
