Jump to content

  •  

CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.

Photo

NGC6888 with Pentax K5 at ISO 80

  • Please log in to reply
6 replies to this topic

#1 Pete_xl

Pete_xl

    Vostok 1

  • -----
  • topic starter
  • Posts: 161
  • Joined: 29 Jan 2015
  • Loc: Germany

Posted 19 March 2017 - 01:30 PM

It was more like a test last October when I set the camera to ISO 80 to get the maximum dynamic range it has on board.

 

http://33492852446_56850436a6_c.jpgNGC6888 Crescent Nebula / Sichelnebel by pete_xl, auf Flickr

 

17 x 300s exposure ISO 80

TS Triplet APO 80/480

Mount AZ-EQ5

Guider MGEN II n 9x50 finder scope

Stacked with Sequator, PP with Photoshop CC217, finish with LR CC2015.8

 


Edited by Pete_xl, 20 March 2017 - 03:03 AM.

  • DuncanM, aneeg and jakob1234 like this

#2 aneeg

aneeg

    Messenger

  • -----
  • Posts: 417
  • Joined: 24 Jan 2016
  • Loc: Nesodden, Norway

Posted 19 March 2017 - 02:33 PM

Fantastic!

Pentax rules!

 

Arne



#3 mikewayne3

mikewayne3

    Surveyor 1

  • -----
  • Posts: 1509
  • Joined: 02 Feb 2009
  • Loc: San Diego CA

Posted 19 March 2017 - 04:25 PM

NICE! like-button.jpg



#4 gfamily

gfamily

    Ranger 4

  • *****
  • Posts: 382
  • Joined: 29 Oct 2013
  • Loc: North Cheshire, UK

Posted 19 March 2017 - 04:47 PM

Hmmm, that's encouraging (see my camera details below)

 

All I need then is 

Confirmation that the Star Advernturer will guide reliably for 300s - should be enough

Low LP skies - can be found

2 hours minutes of uninterrupted clear sky - well, we live in hope. 


  • aneeg likes this

#5 Pete_xl

Pete_xl

    Vostok 1

  • -----
  • topic starter
  • Posts: 161
  • Joined: 29 Jan 2015
  • Loc: Germany

Posted 20 March 2017 - 01:46 AM

Well, my own Star Adventurer was good for about 60-90 seconds with a relatvely light weight 400/5.6 Pentax-A lens. Longer exposures did not make sense because of the periodic error in RA that destroyed to many subs in longer exposures. To fight this I bought an Mgen autoguider. But because the SA is only guidable in RA I was limited by the quality of my polar alignment and had exposure times of max 3 Minutes before the DEC error lead to trails.

 

I am afraid that 300s exposure without guiding and with an even longer/heavier telescope will not work with the SA so it makes no sense to use Iso 80.

 

To find best settings for a K5 I would test what is the longest exposure without trails (not those trails caused by periodic error) at high Iso and then gradually turn down the ISO until the sky background peak is at about 10-20% in the histogram. And then shoot as many subs as the night offers you to get a good base to use the best at least maybe 50 of them.



#6 einarin

einarin

    Viking 1

  • -----
  • Posts: 506
  • Joined: 23 Dec 2016

Posted 20 March 2017 - 02:19 AM

Very nice.

Should correct flickr-link to https://c1.staticfli...6850436a6_c.jpg


  • Pete_xl likes this

#7 Pete_xl

Pete_xl

    Vostok 1

  • -----
  • topic starter
  • Posts: 161
  • Joined: 29 Jan 2015
  • Loc: Germany

Posted 20 March 2017 - 03:05 AM

Very nice.

Should correct flickr-link to https://c1.staticfli...6850436a6_c.jpg

Thank you for the info. The link works now but my problems with building correct links to flickr obviously keep pending confused1.gif


Edited by Pete_xl, 20 March 2017 - 03:06 AM.



CNers have asked about a donation box for Cloudy Nights over the years, so here you go. Donation is not required by any means, so please enjoy your stay.







Cloudy Nights LLC
Cloudy Nights Sponsor: Astronomics