Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-29-2015, 01:46 PM   #16
Veteran Member




Join Date: Dec 2011
Location: UK
Posts: 436
Original Poster
QuoteOriginally posted by stevebrot Quote
Four exposures is four exposures. For your 30s example, the total time open would be a little over 2 minutes. The merged image at best would show a 2 minute star trail with a blip at each 30s mark.


Steve
Yes but....

QuoteOriginally posted by Conqueror Quote
How about 4x 2-to-5 second frames though... resulting in 8-to-20 seconds total (depending on what you choose)


06-29-2015, 06:13 PM   #17
Loyal Site Supporter




Join Date: Jun 2009
Location: Tumbleweed, Arizona
Photos: Gallery | Albums
Posts: 5,107
Folks, the question asked, as I interpreted it was, the color of the Milky Way......
QuoteOriginally posted by LennyBloke Quote
How do you mean "introduced by the photographer" ? Are the colours not already there and just exaggerated by post processing? Sorry for my ignorance
The Milky Way is a galaxy, in which we reside, that is an aggregation of stars, star systems, and various materials/objects. Capturing the Milky Way is a wide angle exercise, not just focusing on a single star. The question asked was not about a single star, but what color is the Milky Way?

You can go outside at night, if your in a dark sky area and look using your eye or capturing an image with your camera. You can also go to the web and take a look at various videos of folks post processing their captured images.

06-29-2015, 07:25 PM   #18
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,424
QuoteOriginally posted by Conqueror Quote
How about 4x 2-to-5 second frames though... resulting in 8-to-20 seconds total (depending on what you choose)
Then you get a 8-to-20 second exposure. I believe that is called a zero-sum solution.


Steve
06-29-2015, 07:29 PM   #19
Loyal Site Supporter
TedH42's Avatar

Join Date: Dec 2011
Location: Colorado
Photos: Gallery
Posts: 480
QuoteOriginally posted by Not a Number Quote
What if you use a star tracking camera mount like the IOptron?
QuoteOriginally posted by interested_observer Quote
I think it will work much better, essentially the camera (pixel shifting) does not know that its moving. But, you are still taking 4 images in quick succession, with a slight movement to move the light to an adjoining pixel. It would probably be better just to have all the light going to the same area (pixel) and then stacking them. This is essentially additive, adding the light from all 4 images together. You should be able to do the same with pixel shifting, but they any pixel will have 1/4 the light, since you were moving from pixel to pixel across each of the images.

This is my question also. Of course, I am going to stack multiple shots (imagine an image of the Andromeda galaxy using a 200mm lens). Assuming an accurate tracking mount, does the pixel shift essentially provide a more effective de-bayering effect than performing it in post processing software? As actual light from a given point in the sky has hit each of the 4 pixels in the relevant "pixel shift group", the PP software does not "need" to do any de-bayering interpolation. This should be "somewhat" similar to using a monochrome astro camera and recording LRGB frames that are combined in PP. (The 30 second limit for each of the 4 positions seems to be quite limiting, definitely requiring stacking.)

I realize that speculation can be done about this operation, but I'm only interested in: has anyone actually done this yet, and is anything useful gained?

Translation: should I consider replacing my K-3 with a K-3ii?

06-29-2015, 07:32 PM   #20
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,424
QuoteOriginally posted by interested_observer Quote
Folks, the question asked, as I interpreted it was, the color of the Milky Way......
Yep and the Web is full of many examples of glorious colors in digital captures of such. The Web is also full of many examples of outrageously unnatural colors in many photos of very natural landscapes, flowers, birds, fish, and animals...not to mention people. The answer there is that one uses software to intensify, exaggerate, and re-interpret what colors information is present in the capture data.

What color is the Milky Way? Well, what color do you want?


Steve
06-29-2015, 07:36 PM   #21
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,424
QuoteOriginally posted by TedH42 Quote
Assuming an accurate tracking mount, does the pixel shift essentially provide a more effective de-bayering effect than performing it in post processing software?
QuoteOriginally posted by TedH42 Quote
Translation: should I consider replacing my K-3 with a K-3ii?
Putting it that way, I would say that is an excellent question, the answer to which is highly dependent on the robustness of the PS process, the precision of the tracking solution, and the effectiveness of the alternatives available for the K-3.


Steve
06-30-2015, 11:56 AM   #22
Veteran Member




Join Date: Dec 2011
Location: UK
Posts: 436
Original Poster
QuoteOriginally posted by stevebrot Quote
Then you get a 8-to-20 second exposure. I believe that is called a zero-sum solution.


Steve
Yes I don't see the problem with 4x 2 seconds resulting in an 8 second exposure... given the right ISO and f stop

If its a clear night devoid of cloud and any objects in the frame other than stars... I really dont see the issue
06-30-2015, 02:03 PM   #23
Site Supporter




Join Date: Mar 2008
Location: Prince George, BC
Photos: Gallery
Posts: 2,342
The confusion stems from our use of the Milky Way as both a galaxy system and as what we see when we view stars of that galaxy along its rotational plane. Most people use it in the latter connotation. Here again, it is the resultant additive combination of the stars along the galactic plane from our viewing point that add up to white.

---------- Post added 06-30-15 at 02:14 PM ----------

QuoteOriginally posted by Not a Number Quote
What if you use a star tracking camera mount like the IOptron?
Yes, good question. The idea behind pixel shift is not to increase the amount of light to each pixel, but to ensure that each pixel receives the *same* light. Since astro work is dealing with recording essentially unchanging beacons of light (judged by our short lifetimes), then as long as your tracking mount is accurate, then I see no reason why PS should not work. The only fly in the ointment is that PS is disabled in Bulb mode where every tracking mount user lives. Still hoping this may be changed in a firmware upgrade.

06-30-2015, 04:37 PM   #24
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,424
QuoteOriginally posted by Conqueror Quote
Yes I don't see the problem with 4x 2 seconds resulting in an 8 second exposure... given the right ISO and f stop
Except that while the shutter is open for a little over 8 seconds, the effective exposure with pixel shift is only the 2 seconds you set on the shutter speed dial. As noted above, a good tracking mount would provide a solution where pixel shift would be practical, though I don't know that it would offer any advantage over the stacking software usually used for astrophotography.


Steve
06-30-2015, 06:23 PM   #25
Pentaxian
Not a Number's Avatar

Join Date: Mar 2012
Location: Venice, CA
Posts: 4,260
Atmospheric distortions would probably cause problems for pixel shift too.
06-30-2015, 06:28 PM   #26
Site Supporter




Join Date: Mar 2008
Location: Prince George, BC
Photos: Gallery
Posts: 2,342
You would need to pick a night with good seeing. Deep sky exposures are often in the 10 minute range anyway. A series of stacked PS images would still be better than a stack of non-PS images.
07-01-2015, 11:19 AM   #27
Veteran Member




Join Date: Dec 2011
Location: UK
Posts: 436
Original Poster
QuoteOriginally posted by stevebrot Quote
As noted above, a good tracking mount would provide a solution where pixel shift would be practical,
Why do you need the tracking with such a short exposure (e.g. 8 seconds total)... it would not trail (with settings such as f2.2 at ISO 400 at 16mm)....
07-01-2015, 12:12 PM   #28
Site Supporter
stevebrot's Avatar

Join Date: Mar 2007
Location: Vancouver (USA)
Photos: Gallery | Albums
Posts: 27,424
QuoteOriginally posted by Conqueror Quote
Why do you need the tracking with such a short exposure (e.g. 8 seconds total)... it would not trail (with settings such as f2.2 at ISO 400 at 16mm)....
Good luck with those settings (2s and f/2.2 @ ISO 400)

More typical would be the settings (3-30s stacked exposures at ISO 3200/6400 and f/2) for this comment on one of your threads from several months ago:

https://www.pentaxforums.com/forums/10-pentax-slr-lens-discussion/287768-da-1...ml#post3142005



Steve

Last edited by stevebrot; 07-01-2015 at 12:24 PM.
07-01-2015, 12:19 PM   #29
Veteran Member




Join Date: Dec 2011
Location: UK
Posts: 436
Original Poster
QuoteOriginally posted by stevebrot Quote
Good luck with those settings f/2.2, 2s, ISO 400.


Steve
Ok yeah brain fried... exposure not long enough

My point is though... with the right combination.. no tracking should be necessary

---------- Post added 07-01-15 at 08:45 PM ----------

OK yes it looks difficult but not impossible [to get away with no tracking and pixel shift]...

Perhaps it'd be possible with:

ISO 3200 f2 8s

Last edited by Conqueror; 07-01-2015 at 12:45 PM.
07-01-2015, 06:43 PM   #30
Site Supporter




Join Date: Mar 2008
Location: Prince George, BC
Photos: Gallery
Posts: 2,342
Tracking mounts are used when a) using long focal length lenses (300mm and above or equivalent); b) long exposures are desired (usually also with long focal lengths). These situations are usually beyond the ability of the O-GPS1.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, color, colors, colours, dslr, exposure, galaxy, ii pixel shift, images, iso, k-3 ii pixel, light, night, nights, photography, pixel, plane, post, ps, shift, shift of stars, sky, stack, star, stars, stars / night
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Questions re: K-3 II pixel shift and Astrotracer gazelle01 Pentax K-3 102 03-06-2017 06:23 PM
K-3 II Pixel shift for Macro? Omestes Pentax K-3 6 06-12-2015 08:13 PM
K-3 ii & Pixel Shift: How still is still? ahw Pentax K-3 19 06-08-2015 09:31 AM
K3 II pixel-shift samples on IR. I'm impressed jonby Pentax K-3 42 06-02-2015 12:28 AM
K-3 II pixel shift resized. Wow factor. JimmyDranox Pentax K-3 21 04-25-2015 09:37 AM



All times are GMT -7. The time now is 10:07 AM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top