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02-07-2013, 06:42 PM   #481
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No problem

QuoteOriginally posted by Ex Finn. Quote
A quick question if you don`t mind. How is the focuser on the 80ED CF handling the K5`s weight, specially with higher elevation shots.
My EON 120 ED with Crayford is a handful, when pointing higher up.

Cheers.
I will usually start with a fairly bright star in view and spend a decent amount of time getting the focus just right. Once I achieve the best focus I can get I set the focus lock, double check with another picture, then start the night. I have been aimed fairly high before though and didn't notice a focus shift. My biggest mistake is usually bumping it with my hand or elbow while I'm switching targets throughout the night.
Something I'm about to try on my next outing is a Bahtinov mask. Hopefully it will assist in the focusing process and make more time for picture taking. The Bahtinov Mask

02-07-2013, 09:48 PM   #482
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QuoteOriginally posted by GWARmachine Quote
I couldn't imagine trying to polar align something while down under. Although the polar scope for the Astrotrac does have guide stars outlined in it, I'm sure it still more difficult than in the north. Hopefully you have good luck with the O-GPS1. I should get mine in a few days! Then I'll be posting pics of stars behind ancient Japanese castles,...hopefully.
Thanks for your great responses.. I imagine the hardest part of the process is actually getting set for the night. I'll be ordering an O-GPS1 next week and hopefully that will whet my appetite.
02-07-2013, 11:38 PM   #483
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QuoteOriginally posted by dbh Quote
Was wondering if any of you intrepid astrophotographers used any external power supply on your camera (especially in the cold) - and if so, what works well?
I had a friend build up a 12V based power supply based on the design offered at drone colony. One of the things that was not covered in the website was that getting good wire is critical. We ended up using ethernet cable and used two conductors per lead to handle the current.

So long as Pentax doesn't change the adapter plug, the power supply should work for everything from K10D to K5 and up.
02-08-2013, 04:12 AM   #484
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QuoteOriginally posted by GWARmachine Quote
Something I'm about to try on my next outing is a Bahtinov mask. Hopefully it will assist in the focusing process and make more time for picture taking. The Bahtinov Mask
Thanks for the link, that looks like it could be very useful.

02-08-2013, 05:03 AM   #485
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Bahtinov Mask tryout

QuoteOriginally posted by Ex Finn. Quote
Thanks for the link, that looks like it could be very useful.
Yeah, I printed mine out on photo paper so it was a bit thicker. Going to get an exacto razor (or whatever they're called) so I can precisely make the cutouts then slap it on and give it a try. I will be sure to post all results too. I also did the same thing that the guy from the website did where I made the slots larger than what it originally said. Looks like it'll work much better this way. I'll keep you posted!
02-08-2013, 05:16 AM   #486
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Bahtinov Mask Purchase

I wonder how strict the tolerances will have to be? Anway, one may find them machined and ready-to-use on eBay:

bahtinov | eBay

Prices aren't that scary, are they?
02-08-2013, 09:05 AM   #487
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I purchased two Bahtinov masks a few years ago from Spike-A. Had a size made that worked for 77mm diameter lens and my guide scope and a size that worked from 102 mm to 127 mm to fit my main scopes. They work very well.

I know people that have cut them out of card stock.

The challenge of working with paper is that it warps when it gets wet, which happens a lot when under the stars with dew.

If you are near a trade school, I bet you could give a project to some kids that are learning CNC metal work. Cutting a bunch of masks with a laser would be a straightforward task and I see that there are ways to generate it on a 3d printer, too.

On further research, I see how one fellow has made a mask extremely simple with just three strings. The idea is to create a diffraction pattern. I like this string concept and will probably use it on smaller lenses where light gathering ability is critical.

Last edited by smigol; 02-08-2013 at 09:10 AM. Reason: added link
02-08-2013, 10:25 AM   #488
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QuoteOriginally posted by dbh Quote
Was wondering if any of you intrepid astrophotographers used any external power supply on your camera (especially in the cold) - and if so, what works well?
I've never had any issues with a fully charged battery and imaging for a couple hours at -20 to -25 C. Should be fine. I always carry spare batteries with me just in case.

02-09-2013, 09:56 AM   #489
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QuoteOriginally posted by smigol Quote
I had a friend build up a 12V based power supply based on the design offered at drone colony. One of the things that was not covered in the website was that getting good wire is critical. We ended up using ethernet cable and used two conductors per lead to handle the current.

So long as Pentax doesn't change the adapter plug, the power supply should work for everything from K10D to K5 and up.
I experimented with the AC power supply and long exposures on my K10D; IIRC, there was a considerable increase in noise when using the adapter. At the time my thinking was that some of the amps and circuits that were shut off to save power in battery only mode were being left on, when the adapter was connected. I wonder if anyone can confirm this?

My planned work around was to use the battery grip and then if more power was needed, I would try and wire a DC power source directly to the leads in the grip. However, I can confirm that the K10D has an internal battery life of better than two hours, when shooting long exposures in bulb mode.
02-09-2013, 02:16 PM   #490
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M42

Took this image last night. Quick stack of two sets, one for the outer area and one for the central core. I'll probably be tinkering with the data for some time.

Camera: Pentax K5 IIs
Telescope: Orion 8" Newtonian
Mount: Skywatcher HEQ5
Guiding: PHD Guiding
Stacking software: PixInsight
Location: Just East of Elk Island National

Exposures:
26 x 3 minute exposures
34 x 45 second exposures

02-09-2013, 10:45 PM   #491
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Just insane results, thank you for posting.
02-10-2013, 03:52 AM   #492
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QuoteOriginally posted by duncan1 Quote
I experimented with the AC power supply and long exposures on my K10D; IIRC, there was a considerable increase in noise when using the adapter. At the time my thinking was that some of the amps and circuits that were shut off to save power in battery only mode were being left on, when the adapter was connected. I wonder if anyone can confirm this?

My planned work around was to use the battery grip and then if more power was needed, I would try and wire a DC power source directly to the leads in the grip. However, I can confirm that the K10D has an internal battery life of better than two hours, when shooting long exposures in bulb mode.
This is not something I've heard before now. I'll check it with my setup.

I have an extensive library of darks to compare against. I'll do some testing and see what I get. When I would use the battery grip on mine there was an annoying habit of the camera dying in mid-shot because it failed to switch batteries.

When I was doing this via battery, I would get 4-6 hours at 20C. My batteries have aged quite a bit now so this may not be as reliable.

Here's my most recent effort. It's not complete yet.




Witch Head Nebula (IC 2118) is a reflection nebula near Rigel.
This is from 24 subs of 1200 seconds long at 100 ISO over two nights with my K10D. Camera cooled to 0-4C. Taken at a nearby dark site.
I want to get back there for another two nights of data if possible this coming week.

Last edited by smigol; 02-10-2013 at 03:56 AM. Reason: added photo
02-10-2013, 01:46 PM   #493
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To Dr_who and Smigol; AWESOME!

Can't wait to see more!
02-10-2013, 02:01 PM   #494
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QuoteOriginally posted by duncan1 Quote
I experimented with the AC power supply and long exposures on my K10D; IIRC, there was a considerable increase in noise when using the adapter. At the time my thinking was that some of the amps and circuits that were shut off to save power in battery only mode were being left on, when the adapter was connected. I wonder if anyone can confirm this?

My planned work around was to use the battery grip and then if more power was needed, I would try and wire a DC power source directly to the leads in the grip. However, I can confirm that the K10D has an internal battery life of better than two hours, when shooting long exposures in bulb mode.
You may find this article helpful:

How to Make a DSLR Battery Run 4 Times Longer | DIYPhotography.net
02-10-2013, 02:33 PM   #495
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I'm hoping to break into astrophotography myself with a couple of my lenses and the O-GPS1 astrotracker. One lens I picked up over the past summer (while waiting for the cash to buy a new camera, as my K-x broke) was a completely off-off brand 200mm prime. I've been testing it to see how sharp it is, and I think I may have a winner for using in tandem with the tracker.

Better yet, it plays well with a 2X teleconverter I have, so I essentially have a sharp 400mm prime as well. I'm hoping to sneak out around midnight and see how things go despite the fugly light pollution here in town.

If all goes well, I can drive the half hour out to our property in the boonies for some long night sessions once the weather gets beyond 'freeze your acorns off'.
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