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09-08-2012, 02:29 AM   #136
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Life view for focussing on stars

Dear Members,

DSLRs make people dream. Finally one could focus on the life view screen and even zoom electronically before focussing. Is this theory?
I posted a few days ago a question about lens focussing on the night sky (zooming in 32x on star pictures start showing coma and focus quality). For astrophoto's one would put the lens focussing on infinity and forum members explained that the infinite setting on the lens takes also a margin for thermal dilatation. I tried to focus manually around the infinity mark but this is not very easy via the viewfinder. If one could use the life view function this would be fantastic, but stars are so faint that there seems to be not sufficient light to show the star image on the life view screen. is there a solution for this?

Using life view is heating up the sensor (constant pumping image data to the processor) and will increase the noise in the image. The K-5 seems to be the best performing DSLR on the market in its category as far as low noise is concerned (the amplifier from Pentax seems to be much better compared to the competitors using the same sensor) and this is the reason why I bought the K-5 for astro-purposes.

Regards,

Stefan

09-08-2012, 03:00 AM   #137
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QuoteOriginally posted by noste99 Quote
Dear Members,

- - - - -, but stars are so faint that there seems to be not sufficient light to show the star image on the life view screen. is there a solution for this?

- - - -

Regards,

Stefan
I regularly use the brighter stars and live view for focus check - in particular with my 350mm catadioptric lens that focuses way beyond infinity. With the brigtest stars such as Vega, this is easy. With the somewhat fainter stars you will have to use live view nagnification a good deal to see the stars. (And at 10X magnification you will also have an often horrifying demonstration of your seeing conditions). Often, you will also have the Moon, Venus, Juppiter, Saturn for focus check.

What you cannot really use live view for is confirmation that you fainter targets are actually in your field of view. For tripod mounted cameras I use som home made finderscopes and brackets of this type:



You can often find used, cheap spotting scopes that may serve for this purpose.
09-13-2012, 04:24 AM   #138
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Urban Astrotracer Fun

While I am waiting for autumn's showpieces to position themselves in front and above my S-SW facing fourth floor balcony under a severely (also) light polluted sky, I still have fun training my 350mm Tamron mirror lens and Astrotracer around the Summer Triangle. Maximum allowable exposure times seems to be shorter and still, stars are often a bit more elongated than when I am in the country side.

I guess I do have a problem of magnetic anomalies here, but nonetheless I can capture targets such as:


Planetary nebula M57 in Lyra. Ten exposures of 20s at ISO 1600 stacked in Deep Sky Stacker and post-processed
in PhotoImpact.


Globular Cluster M56 in Lyra. Eleven exposures of 20s and five exposures of 12s, all at ISO 1600, stacked in DSS
and post-processed in PhotoImpact.

OK, stars aren't perfect circular dots, but anyway: How else would I get such pictures with camera on a fixed tripod
and a long lens, that would otherwise produce unguided / "untraced" images like this:


Single exposure of 20s at ISO 1600. Note the less than perfect seeing.

All images shown above are 100% non-resized crops. Click on images to see the objects in their "natural habitat" (100% crops downsized to 55%).

To me this is confirmation that the O-GPS1 and Astrotracer is indeed a fine little travel and/or grab-and-go companion.

Last edited by Stone G.; 09-13-2012 at 04:33 AM.
09-19-2012, 02:11 PM   #139
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I focus thru the live view on a near by bright constellation star. They tend to be bright enough, you can also just take a short 30 second exposure to just test teh focus and see how it is before and do adjustments before doing any longer 2-5 minute or longer exposures.

09-20-2012, 12:27 AM   #140
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Astrophotos from Bali night skies...

Hi,

Share with you guys what I got with my K5 + 50-200mmWR + O-GPS1. All these are uncrop version.











Regards,

Tommy
09-20-2012, 05:12 AM   #141
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QuoteOriginally posted by kamayok3 Quote
Hi,

Share with you guys what I got with my K5 + 50-200mmWR + O-GPS1. All these are uncrop version.

Regards,

Tommy
Nice shots.
09-20-2012, 07:55 AM   #142
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Excellent shots kaymayok. I take it you live somewhere with dark skies? If I tried shots like that around here the image would be completely white.
09-20-2012, 08:14 PM   #143
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I bought a used flat screen monitor with an hdmi port for $30 dollars. Attached it to my K-5 and wow what a great tool for astro photography. In live view you have the ability to fine focus and center easily and then see your results in high definition. I have been using the old M 28 2.8 and m50 1.4. I picked up a vivitar series 1 210mm 3.5 and the focus is amazingly sharp. Here is m27 using a vivitar series 1 210mm lens

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09-22-2012, 01:42 AM - 1 Like   #144
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Another shot by O-GPS1

Hope you guys like it.
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10-09-2012, 11:38 PM   #145
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Nowhere up to Kamayok's dark skies but I did manage NGC7000 (North America Nebula) tonight as it was near the zenith for my location. O-GPS1 did its thing well and most of the stars rendered round enough. Also managed to record a sporadic meteor streaking top center to bottom right of the frame. Deneb is the bright star to the right of the frame. Details of setup: S-M-C Takumar 135/2.8 @ f2.8, 50 seconds, ISO3200, mirror lockup with remote shutter release by Pentax Remote F unit.
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10-09-2012, 11:58 PM   #146
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Nice pictures everyone. Weather here is terrible.. only rain or cloudy. I don't like autumn

jbinpg, I'm sorry but to me that looks like satellite, not meteor. But hey, I can be wrong
10-10-2012, 12:02 AM   #147
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Nope, pretty sure it was a meteor. Satellites usually show constant changes in brightness across a frame, even one as narrow as this. And I caught several others in separate frames as well.
10-11-2012, 04:41 AM   #148
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QuoteOriginally posted by Stone G. Quote
I still have fun training my 350mm Tamron mirror lens and Astrotracer around the Summer Triangle.
Great stuff!

Have you ever taken your equipment to Lake Tekapo?
Awesome conditions over there.

Not sure whether I've ever invited to join us Kiwi Pentaxians...
10-11-2012, 07:23 AM   #149
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QuoteOriginally posted by Class A Quote
Great stuff!

Have you ever taken your equipment to Lake Tekapo?
Awesome conditions over there.

Not sure whether I've ever invited to join us Kiwi Pentaxians...
Why, thank you Class A! But you see, I live on the island of Zealand, Denmark. Draw a line from your place straight through the Cenrtre of the Earth and you won't miss me.

New Zealand is high on my wish list, though. Ah, dark skies and the celestial wonders of the Southern Sky...................
10-11-2012, 09:59 AM   #150
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Hoping to give photos a go this weekend if it stops snowing :S
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