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07-10-2018, 03:48 PM   #16
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QuoteOriginally posted by Ian Stuart Forsyth Quote
I picked up a star adventurer, I see you live in Alberta it might be worth you time to chat with
All-Star Telescope - Telescope and Astronomy Sales for Calgary, Edmonton, and Central Alberta they are in the Didsbury area and are very friendly.

I like the star adventurer for tracking up to 10min with very little drifted, here is 2 images overlaid without any photoshop auto aligning with a total of 10min worth of tracking just to see how much drifting I could expect. Crop of the lower left of the frame.




I would recommend downloading an app for your cell that will aid in polar alignment that gives you realtime and location corrections for polar alignment.

Also to speed up setup I found if you have a way of aligning your tracker vertical so that you can level the crosshairs in the polar alignment reticular with a level it is rather quick to setup in the field

I just use a level attached to the main plate. once level its very easy to sight for polar alignment



https://3.img-dpreview.com/files/p/E~forums/60366564/0cd54d1d3e5643b18948f71a568fdac4

One nice feature I also like is the half speed tracking, with this you can track at half of the speed needed and this allows you shoot landscape in the scene and what essentially does is allows you to place half of the stars movement into the landscape and half of the movement in the stars. This way you can shoot with a shutter speed of twice as long as you would use normally without a tracker.

You will also find the tracker useful for time lapse where you want to pan during the video that can also be setup to trip the camera's shutter with a lot of customizable options
Nice setup you have they’re. Specially the tripod lol.

---------- Post added 07-10-18 at 04:48 PM ----------

QuoteOriginally posted by MossyRocks Quote
my $0.02
Both pictures you provided look fairly reasonable. As astrotracer doesn't do rotation longer exposures will show trails as you move out from the center. Also at 260 seconds you really are really close to the upper limit of what astrotracer supports. Instead I would have probably shot that scene as 6 to 8 60 second exposures at ISO1600 and stacked the individual images using Deep Sky Stacker. Between each shot I would have recomposed the image to keep the center as close as possible to the original image. My general rule is to try and keep astrotracer exposures to under 1/4 of the suggested maximum as it seems like the errors really do start adding up.

Your first image looks like it isn't fully in focus, I would suggest getting or making a bahtinov mask so that you can nail the focus. I would also suggest going to f/4 to see if that helps.

I have had pretty good luck using the O-GPS1 on my K-3. I have been chasing some deep sky objects and as I am not all that good at finding them I end up with star field pictures. I started without any form of tracking and would just crank up the ISO so that I could avoid trails. The biggest improvements I had were when I did the following:
1. Getting a heavier tripod
2. Using the 2 second mirror up delay with shutter release cable
3. getting bahtinov mask for focusing
Astrotracer helped but that is only because it allowed longer single frame exposures. That can be made up for with a bunch more short exposures at a higher ISO. Try to eliminate other sources of error before throwing more expensive gear at the problem. Also astrotracer goes sideways fast if not calibrated correctly. It went sideways on me Saturday night and I got one frame that had the whirlpool galaxy (M51) in it where the galaxy was just above the noise floor of the image and the in rest something went wrong and I ended up with star trails going in all sorts of directions. The good one was the first one where I was checking that the settings were producing something sane and that the calibration was correct so things went wrong after that. I think it is because the battery may be dying in the O-GPS1 as it is the one I first put in it.
Where do you get that Balhtinov mask?

07-10-2018, 03:57 PM - 1 Like   #17
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As MossyRocks points out, shorter exposure time and stack the pictures using Deep Sky Stacker, this one is 35x10sec ISO1600, K-70 with gps and my DA*300mm. Rather short exposure time, it just shows what is possible.

07-16-2018, 09:01 AM   #18
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QuoteOriginally posted by AI8877 Quote
Where do you get that Balhtinov mask?
I think you can find some on sale on amazon but they are likely expensive and meant for a larger telescope so may not work for you. For the one I made I used this online template generator which produces a SVG file. I printed that off and taped it onto a 3" PVC pipe cap and cut out the slots with a dremel. It is better than other methods I have used but getting a better, more accurate one is in the works, but for $2 and 30 minutes of effort it provides pretty good results. For that I want to get one 3d printed and there are sites that will convert a SVG image into a stl file for a 3d printer.
07-16-2018, 06:02 PM   #19
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QuoteOriginally posted by MossyRocks Quote
I think you can find some on sale on amazon but they are likely expensive and meant for a larger telescope so may not work for you. For the one I made I used this online template generator which produces a SVG file. I printed that off and taped it onto a 3" PVC pipe cap and cut out the slots with a dremel. It is better than other methods I have used but getting a better, more accurate one is in the works, but for $2 and 30 minutes of effort it provides pretty good results. For that I want to get one 3d printed and there are sites that will convert a SVG image into a stl file for a 3d printer.
Actually, there are some ready-made 3D programs for the mask on ThingUniverse which you can use with a 3D printer if you have access. Not sure on the size but if you are handy with 3D printing, you can rescale the mask pretty easily. Printing one on transparency material seems the easy way to go as long as it's removed for the exposure.

Bahtinov Mask Generator by brentb - Thingiverse

Here's a jpeg that can be scaled to fit your needs:

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Last edited by Bob 256; 07-16-2018 at 06:10 PM.
07-17-2018, 06:45 AM - 1 Like   #20
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QuoteOriginally posted by Bob 256 Quote
Actually, there are some ready-made 3D programs for the mask on ThingUniverse which you can use with a 3D printer if you have access. Not sure on the size but if you are handy with 3D printing, you can rescale the mask pretty easily. Printing one on transparency material seems the easy way to go as long as it's removed for the exposure.

Bahtinov Mask Generator by brentb - Thingiverse

Here's a jpeg that can be scaled to fit your needs:
I actually made a 3d model of one last night from an SVG and it wasn't too difficult to do once I figured out how to start to work with freeCAD. My goal is to have one I can stuff inside the lens hood of my 300mm f/4 SMC takumar lens. Since I am not going to be cutting things out I have been playing with settings to get as many slots as possible so that the image for focusing is as bright as possible.
07-17-2018, 07:09 AM - 1 Like   #21
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You can brighten the image by making the slots as wide as possible (and the bars that block light thinner). The width of the bars isn't important as long as they are straight. They could be pretty thin and the mask would still work since it's the diffraction of light off the pattern that makes focusing possible. Good astro-shooting!
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