Hi guys!
So story is, bought a star adventurer to use with my Nikon dslr (d810 with 70-200 2.8 and sigma art 50mm mostly)
all went great when I got it about a year ago, managed 30 second subs with a 300mm f4 easily with only laser and eye alignment method. flash forward after a break and last night, I finally used my polar scope and nailed octans perfectly. thought you beauty, gonna get awesome results here!
very disappointed. this attached is 30 seconds at 200mm, 15 seconds looks fine but this is terrible. I checked alignment during and it was fine... any ideas what's happening here?? 4 minutes at 50mm was terrible too. Doubt its camera shake, using a timer and going by the movement.. but could be wrong. Also seemed to be better when I removed the counterweight setup..
any help much my appreciated, cheers!!
Tim
Tim, there may be nothing wrong with the mount 's tracking. I was photographing Orion last night at about 11.00pm with a Nano Tracker. By this time the constellation is past the meridian and the camera will be weighted to the west. If the camera is not attached securely enough it may be slowly moving toward that direction, giving the impression that your mount is not tracking correctly.
Make sure all clamps and connections are tight and weight your camera slightly to the east so that it's weight puts tension on the mount's drive system. This may not be what's happening but can be something to try in an elimination process to find a cause.
Good luck.
Agree with you on that one Mickoid.
Was out testing my widefield setup after experiencing what TIM has described and dicovered that the camera is very sensitive to movement. Even walking around the tripod can upset it whilst shooting your exposures. The counterweight can slip during tracking as the extension rod on my mount has some movement in it. So I think rid the counterweight completely. The mount should handle the weight of the camera on its own without too much problem.
Also add in a 15sec delay after activating the shutter to avoid any residual shake after the mirror flip, and avoid any loose cables attached to the camera from fouling during exposure such as an intervelometer. The slightest touch from a small breeze can cause issues here too.
thanks muchly guys, feeling a bit better now! I was so stoked to finally spy octans and then super disappointed!
Will try on the next clear night
By the way, is there a direction or points that tend to show up trailing more than others? not sure if I have that right or not, like further away from the pole star ie north?
Definitely, like anything that rotates around a central axis, the centre moves much slower than the extremities. A good example is taking a shot of the sky on a fixed tripod. At a given exposure, stars near the SCP will always exhibit less trailing than those further away. For example, with a 50mm lens you might get away with a 20 sec exposure at f2, 1600 ISO around the Crux constellation but try the same exposure near Orion and there may be star trailing evident.
I had a go a few nights back and did a lot better! 2 minute subs at 200mm! Was very happy. Went out again tonight and no go... horrible trailing, checked and checked polar alignment, a tiny bit out after loading the camera on. Still the same result. It's extremely frustrating not being able to check alignment properly when it's loaded.
After tonight I'm seriously thinking of offloading it for a proper mount, any ideas? I can find octans easily now, so tracking up to 3-4+ minutes at 400mm would be ace. A set up that's a lot more 'solid' would be good too, to not worry about vibrations or knocks.
I think the minimum recommended for astro imaging would be an EQ5 or equivalent. EQ6 is better but it all depends on your budget and long term imaging plans. If you intend to go to a scope later then EQ6. Others may have other suppliers offerings, Ioptron etc but in imaging the mount is the key.
Tim, if you just want to do widefields with standard camera lenses then the Star Adventurer should be fine. The fact you got it working properly one night and not the next indicates something is moving after you've polar aligned. You may just need a more robust tripod. If the legs aren't tightened they may be moving when you place the camera on. A flimsy cheap tripod won't be capable of giving you consistent results. Also, are you placing the tripod on a solid surface? If I'm taking my Heq5 out in the field, I always place it on small concrete pavers which I bring with me to prevent the legs settling into the ground after it's been levelled.
setting it up on concrete, my tripod is a very solid manfrotto one.
You're probably right, I'm just getting frustrated as there's no way to check alignment and properly balance at the same time when loaded up..
Combine that with awkwardly staring up through the polar scope on the ground, trying to hold a red torch out the front and playing with the alignment knobs that flex around and it makes for a lot of frustration!
I'll keep trying though
Do you have a dog?
I recall near going bats once because my stars looked like worms.
My little darling black dog had laid down under my scope...you can guess the rest.
Test with a static shot which may show the camera is moving on its fitting.
Anyways it is a problem and there will be a solution. Good luck.
Alex
haha! I do but I was supervising the whole time
these were definite slight curved trails!
thanks though!
good idea to test statically, will try next clear night (hopefully in a few hours)
