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06-22-2014, 02:30 PM   #826
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Hi Friends,
I've been away for a bit. Kinda took a break after some recent unfortunate experiences with my kit.

A while back I had a hell of a time with trying to get focus so I could use some tips on focusing a FA100/2.8Macro and a SMC 67 200/4.

I've focused on objects far far away, like a streetlight several kilometers away, using and not using liveview, just bare focusing on a brighter object, like the moon or polaris to no avail. I meant to but did not at the time but I will locate some good wide rubber bands to help dampen/hold focus.
That's about it. Any help is much appreciated.

I read about bahtinov masks but making one seems like a PIA, and not sure I saw any for purchase for my lens sizes.

You're ALL wunderbar!
Thanks
John

06-23-2014, 07:07 AM   #827
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Eta Carina Nebula - NGC3372. 86 x 1 minute subs, ED100 at F7.2, HEQ5 Pro goto, Pentax K-x.

Bigger at Astrobin. NGC3372 Eta Carina Nebula (Kevin) | AstroBin
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06-23-2014, 01:08 PM   #828
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QuoteOriginally posted by Iksobarg Quote
A while back I had a hell of a time with trying to get focus so I could use some tips on focusing a FA100/2.8Macro and a SMC 67 200/4.

I've focused on objects far far away, like a streetlight several kilometers away, using and not using liveview, just bare focusing on a brighter object, like the moon or polaris to no avail.

I read about bahtinov masks but making one seems like a PIA, and not sure I saw any for purchase for my lens sizes.

John,

I use two sizes of Bahtinov masks, both purchased from Spike A (spike-a.com). The smaller size is appropriate for 77mm diameter lenses. I've used it well on 67mm diameter lenses, too.

The important thing to note for camera lenses is to be patient. You'll not see spikes except when overexposing the stars. I'll see good spikes on Vega with 6 second exposures at 100 ISO.

Another thing about camera lenses is that you will have better star shapes and better spikes when stopping down one step. More than one step may introduce additional spikes from the aperture blades, so I don't suggest going that far.

I'll dig up some examples of how I've used the tool to focus camera lenses and post them.

Stephen
06-23-2014, 07:02 PM   #829
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Awesome shots Kevin! I'm gonna try and get some pics tonight hopefully - the skies look magic this morning

06-23-2014, 07:55 PM   #830
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Thanks Mike. Good luck!
06-24-2014, 07:02 AM - 1 Like   #831
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Omega Centauri - 450 second exposure @ ISO800. Skywatcher ED100 - Mackay Qld in average seeing conditions.
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06-24-2014, 07:03 AM   #832
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My first proper attempt at a DSO object - M20 the Trifid Nebula! Not bad for a single 720 second exposure Guided by PHD with Orion SSAG. Pentax K3 @ ISO800
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06-24-2014, 05:43 PM   #833
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Got notice of my O-GPS1 shipping today. I hope to give it a shot.

06-24-2014, 10:27 PM   #834
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Blimey Mike, they are better than my K-x can do with 10 times the total exposure. Really hoping the coming K-5 can do as well.

This is my Omega Centauri from last night. 85 x 1 minute subs, ED100 at F7.2.

Bigger at Astrobin. Omega Centauri NGC5139 (Kevin) | AstroBin
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06-24-2014, 11:20 PM   #835
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Thanks Kevin! I was using the 2.5x Powermate as well with those pics last night - gonna do some more imaging tonight after indoor - should be a good night with low humidity however the seeing index is poor so we'll see. Yours turned out well! Nice and sharp. I've got a bahtinov mask coming to help me focus, I'm buggered if I can achieve pin point focus sometimes hey. I'll use the field flattener/reducer tonight to get rid of the coma

Last edited by weathermon; 06-25-2014 at 12:02 AM.
06-25-2014, 01:17 AM   #836
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M13 in Hercules with K10D

This is a shot of the globular cluster Messier 13, in Hercules. Taken over two nights in the backyard for testing prior to GSSP 2014.




This image is a sum of 18 exposures at 1200 seconds each at 100 ISO.
Standard setup: Stellarvue SV4, Pentax K10D (modified and cooled - and broken shutter), SSF6 flattener
Filter: IDAS HEUIB II
Mount: Losmandy G11 with Gemini 2

Was challenged to fix some problems with camera and mount prior to the star party. The mount part was easy - I re routed some cables so that they didn't snag. The camera part was not easy. During waiting fo rthe skies to clear, I ran the camera to capture a series of dark frames. Unfortunately, during these sequences a piece of flocking paper fell down into the camera body and blocked the movement of the shutter. The shutter electronics a dead and now it will not open. I've had to hot glue the shutter open and now rely on the motion of the mirror plus the electronics of the CCD to time the exposures. Biggest follow up to the shutter issue has been taking flats. Because short duration flats allow over exposure as the mirror flaps up and down, long duration flats are better. I'm now recording flats with a duration of .7 seconds vs 1/60 second. I may consider building a strobe box to further experiment.
06-25-2014, 03:49 AM   #837
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QuoteOriginally posted by smigol Quote
This is a shot of the globular cluster Messier 13, in Hercules. Taken over two nights in the backyard for testing prior to GSSP 2014.









This image is a sum of 18 exposures at 1200 seconds each at 100 ISO.

Standard setup: Stellarvue SV4, Pentax K10D (modified and cooled - and broken shutter), SSF6 flattener

Filter: IDAS HEUIB II

Mount: Losmandy G11 with Gemini 2



Was challenged to fix some problems with camera and mount prior to the star party. The mount part was easy - I re routed some cables so that they didn't snag. The camera part was not easy. During waiting fo rthe skies to clear, I ran the camera to capture a series of dark frames. Unfortunately, during these sequences a piece of flocking paper fell down into the camera body and blocked the movement of the shutter. The shutter electronics a dead and now it will not open. I've had to hot glue the shutter open and now rely on the motion of the mirror plus the electronics of the CCD to time the exposures. Biggest follow up to the shutter issue has been taking flats. Because short duration flats allow over exposure as the mirror flaps up and down, long duration flats are better. I'm now recording flats with a duration of .7 seconds vs 1/60 second. I may consider building a strobe box to further experiment.

Saw and faved this on Flickr - it's just wonderful!

Condolences on your camera though :/
06-25-2014, 05:34 AM   #838
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Nice shot Smigol! Well that's my night over before I even started with pics unforecast high level cloud came over and ruined everything... hopefully better luck tomorrow.
06-25-2014, 06:58 AM   #839
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Saw that coming on MTsat Mike. I got a couple of shots in before it arrived. But I'm not showing anyone because they were taken with the Nikon. :P

Beautiful image of M13 Stephen. Would love to get that much clear sky time. Sorry about the camera.
06-25-2014, 08:13 AM - 1 Like   #840
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This is my favourite open cluster NGC3532. 60 x 1 minute subs, ED100 at F7.2, Pentax K-x.

Bigger at Astrobin. NGC3532 (Kevin) | AstroBin
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