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08-05-2016, 03:08 AM   #16
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Hi, nice shot, however I seem to see movement of the stars which are not perfectly "still" even though the Astrotracer function is active, like the movement of the sensor didn't track Earth's movement correctly.
Is that the case?
I'm asking because I'm about to purchase an O-GPS1 module to use with my K30 and would like to know how the Astrotracer function in Pentax bodies performs.
I'll be upgarding to K1 next year, so that is even more interesting to me.

Thanx

08-05-2016, 07:30 AM   #17
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Does the stacking feature allow you to capture in raw or jpg only? Thanks for the heads up, was not aware of this.

First blush, with the K1 and astrotracker, I was a bit disappointed as with the 15-30 @ 15mm and F 3.2 the astrotacking still allow star trails towards the edge of the frame. I also have a darker off color band towards the top of all frames, not sure if that is a camera issue or what. GPS was calibrated and actually was very close the garmin I was checking with.

On center the feature works great, low to nominal noise, but still the sides are critical and still trailed. Intestinally the actual Milky way in the back ground is still in focus. In the past with other cameras, if you allow the trails, then the actual Milky way will blur slightly making it hard on the eyes.

Called Pentax yesterday, and again not to impressed. 1st person did not know what the feature was, and the 2nd person tried to tell me there was 2 versions of the 15-30 zoom (which I don't believe there are), 3rd person knew about the astrotracker, but spend 10 minutes trying to find Pentax examples taken with the 15-30, which they did not find, but never asked me to send in my shots. Which also surprised me.

If you are working in the middle US, and want more than just the sky, you will need at least 20mm, better 15 to 14mm as you just can't get enough subject in to make a image worth while. Out west, might be able to get away with 24mm to 35mm.

Images are very clean in the sky, still pretty noisy in the foreground.

Pentax also seems to have the same problem that Nikon did when they first released the D810, (white dot issue), as the files being to get filled with white dots. You can eliminate most of them if you allow the long exposure noise reduction to be ON, but that locks up the camera for the same time as the previous exposures (just like Nikon which also surprised me must be something about the Sony chip).

Will try to get a sample posted later today showing problems.

Paul C
08-05-2016, 07:59 AM   #18
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QuoteOriginally posted by Paul2660 Quote
Pentax also seems to have the same problem that Nikon did when they first released the D810, (white dot issue), as the files being to get filled with white dots. You can eliminate most of them if you allow the long exposure noise reduction to be ON, but that locks up the camera for the same time as the previous exposures (just like Nikon which also surprised me must be something about the Sony chip).

Will try to get a sample posted later today showing problems.

Paul C
White dot issue? Yes please do show some examples.
08-05-2016, 08:30 AM   #19
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When the D810 was first released, there was a huge issue in the Astro world and long exposure world, in that the D810 in long exposures showed a large number of small white dots, unlike noise, which tends to be in various colors, these were all white.

Nikon ended up recalling all the original D810's that were shipped and a fix was made along with firmware. The firmware could not be applied by the enduser so I assume a e-prompt of some kind was added to the chip. All cameras that were fixed and shipped correct had a black dot inside the tripod mount.

This was a huge issue and as I can remember the only major recall Nikon had on the D810, my camera was affected and fixed by Nikon.

Sadly I see some of the same dot's in a lot of my non-in camera noise corrected shots. For MilkyWay, not a huge problem to apply it, but if you are stacking for star trails which I do a lot of, then you can't apply in camera noise reduction for long exposures as you will gap way too much to correct in post (star tracer). So for star trail photography, it's possible the K1 will not be a good fit unless you use Capture One, by Phase One as it has by far the best ability to remove the dots without excessive details.

Here is a old link to Nikon's recall:

Service Advisory

Examples from the D810 which look the same to what I am seeing with the K1.

D800 Reticulation issues during night photography–white dot problems @ Photos Of Arkansas

Paul C
Photos Of Arkansas

08-05-2016, 08:57 AM   #20
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Here are a few screen shots.
Image on right is a pixel shift (taken to see if noise levels would be lower) and image on right is 2 minute astrotracker

Image 1 shows a side by side 25 sec on left and 2 min on right, basically almost full star trails on the astro tracking image
Image 2 show a crop from dead center and if anything the astro tracker shot is a bit out of focus
Image 3 shows a crop from top middle, and here the stars are sharp, and no trails
Image 4 shows full images, mainly to show the dark color band toward top of all files, this appears on all images taken in either astro tracker or Pixel shift @ 25", did not try traditional stacking to see if band still shows. This is bigger show stopper than anything as it has to be corrected each time. in the side by sides, I have already worked on the band so it's not as evident.

Also note that the Milky way is blurred in the 1st screen shot, so basically astro tracker failed 100% here. GPS was fully calibrated and confirmed to be so.


Images worked in Capture One.

Paul C
Attached Images
       
08-05-2016, 10:49 AM - 1 Like   #21
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example of white dots,

Attached screen shot, shows the problem quite well. This is from LR, which can't ever handle any stuck pixel noise anyway, but the problem manifests itself just like the D810. The image on the left was shot with in camera noise reduction ON, the Right it's off. So for Astro work of the M Way you can go that way, but it's a NO GO for any star trail work, due to the dots. When you stack, all the dots will create dotted lines thus ruining the shot. I had hoped Pentax would have done their home work on this, but obviously they did not as the problem was found by Nikon over 2 years ago on the same chip. Can't get the attachment large enough to really show it, but the dots are there.


Edit, it shows up much better here:

http://www.getdpi.com/forum/pentax/59293-k1-white-dot-issues-same-d810.html#post701089

Paul C
Attached Images
 

Last edited by Paul2660; 08-05-2016 at 10:58 AM.
08-05-2016, 11:13 AM - 1 Like   #22
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I noticed the white-dots issue my first time taking the K-1 out.

Here's how I work around it on star trails shots:

Load your images into a stack in photoshop, convert to smart object. Change blend mode to "Maximum" -> creates the star trails, also accumulates the dots.
Duplicate your star trails layer. Change smart object blend mode to "mean". This averages out the dots and removes the noise for all static (ie. non-star) objects.

Then I create a luminosity mask in the star trails layer. Modify the properties of the luminosity mask such that it's selected only the star trails (not the white dots nor the foreground or dark sky), then quick-mask the layer, and paint white inside the quick mask to only show the unaffected star trails.

The end output has the pure star trails in their exact color and configuration. They are overlaid over the averaged layer. The foreground and skies are averaged out to reduce noise (and dissolve out those white dots too).

It's a bit more legwork on the post-processing end, but it gets rid of them. And the extra benefit is the averaging noise reduction too.

---------- Post added 08-05-16 at 01:17 PM ----------

Extra note: when I go out for astro work, I shoot star trails with the K-5iis and shoot static Milky Way shots with the K-1. Two totally different shots per setup location, and usually the time it takes to set up and complete a great shot of the Milky Way has also given enough lapsed time to develop long trails on the K-5iis.
08-05-2016, 12:07 PM   #23
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QuoteOriginally posted by Paul2660 Quote
Attached screen shot, shows the problem quite well. This is from LR, which can't ever handle any stuck pixel noise anyway, but the problem manifests itself just like the D810. The image on the left was shot with in camera noise reduction ON, the Right it's off. So for Astro work of the M Way you can go that way, but it's a NO GO for any star trail work, due to the dots. When you stack, all the dots will create dotted lines thus ruining the shot. I had hoped Pentax would have done their home work on this, but obviously they did not as the problem was found by Nikon over 2 years ago on the same chip. Can't get the attachment large enough to really show it, but the dots are there.


Edit, it shows up much better here:

K1 and white dot issues (Same as the D810)

Paul C
What the ¤%&%¤# this is a serious problem!

Is there a simple way to provoke this to appear, or is there temperature involved?

It would be interesting to know if this affects all K-1 or only some.

A question, does the K-1 get warm while doing long exposures? Warm as in you can actually feel an increased body temperature when touching the camera body.


Last edited by Gimbal; 08-05-2016 at 12:20 PM.
08-05-2016, 12:44 PM   #24
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As a user of the D810 Nikon, I noticed this issue as soon as I received by camera. Nikon apparently loaned some D810 to Astro photographers during the early days and they noted the issue. The D800e also had this problem (at least mine did) but later versions did not so an internal fix was made.

The same fix did not get first applied to the D810, but was retro fitted somehow to all the effected cameras.

The effect is the same with the K1, and yes the effect is worse as the camera gets hot. My conditions were about the worst, as I had 100% humidity and about 92 degree F heat even that late at night. My camera was however not warm to the touch ever, and I have noticed the warm to the touch with both my X-Pro2 and Nikon D750, the later can get quite warm on an Arkansas night shoot.

The in camera noise reduction remove the vast majority of it so for Milky Way work I would just turn it on and wait the extra time, but for star trails, really no an option.

Pentax more than likely did not consider star trails, (most companies don't) and what is really required to get a good image (it's actually a lot more work than most understand or want to mess with), they must have seen this issue, or surely knew about the Nikon problem, so their fix is "long exposure noise reduction" same as Sony with the A7rII. Which is why I did not keep the Sony as it's even worse than Pentax.

Paul C
08-05-2016, 02:41 PM   #25
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In camera dark frame subtraction isn't an option in my opinion as it takes to much time, time that should be used to gather light.
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