[mblanc]

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I finally had a chance to try my Kx this winter. Stock 18-55 lens set at 55mm f/3.5, tripod mounted, ISO 1200, 16x 20” exposures w/dfs.
Images stacked with DSS, levels and curves in PS CS5.
The stars show signs of trailing at 20”.
As soon as the temp gets out of the teens, and I have a clear sky, I’m going to try my 300mm riding on my scope.

Newbie question - is DSS Daylight Sync Shooting? Or is it something in Photoshop?

[Ex Finn.]

DSS stands for Deep Sky Stacker. "DeepSkyStacker is a freeware for astrophotographers that simplifies all the pre-processing steps of deep sky pictures".
Here is the link.

DeepSkyStacker - Free

[miroshi]

hi to all,
i read almost all post. it was very interesting for me. as i am new in all this i will ask some questions and try to make some conclusions. if i repeat some you can answer me with personal message.

equipment for astrophotography:
pentax k-x;
lens with width aperture - f1.4 or f2.8;
tripod - static or rotating;
software for stacking like deep sky stacker;
some program like cybersky or stellarium - for find space objects;
telescope (i am planing to buy ;
and some other extras;

astrophotography techniques using static tripod:
moon;
star tracks - when exposure is over 1 min.;
stars - high iso and exposure max 30 sec.;
for nebulas we need min 150-200mm lens;

if i want to shot stars i need to make 20 or more shots with no moving of camera, with wider possible aperture and then stack all pictures with software. the last one will make one picture using all my frames with minimum manual corrections.
can i use this technique when shot star tracks? or it is not necessary?
what about NR when i shot with exposure till 30 sec? is NR good or not?

BUT what if i want to shot some nebula at 250mm? when we zoom the stars move faster? the aperture will be f4 or more. if i wait less 30 seconds the light will not be enough, and the stars movement will be bigger. what to do in this case?

if i have telescope i can attach the camera on it. there are connectors for different cameras, right?

astrophotography techniques using moving tripod:
with it i can reduce earth rotation and can make exposures from minutes till hours.

please correct me if i am get wrong somewhere!
thanks!
best regards!

[JohnT-W0JT]

I realize that this thread has not had any activity for 10 months, but is it outdated, or am I missing something?

The thread bemoans the inability to turn off DFS (Dark Frame Subtraction) on the Pentax K-x for long exposures. From what I read here, the problem is that an exposure of, for example, 60 seconds, requires another 60 seconds or so of internal camera processing (to perform DFS) before the camera is ready to take another picture. Am I understanding this part correctly?

When I review the MENU functions in my K-x, if I go to the C2 menu, item 13, "Slow Shutter Speed NR", the options are 1=On and 2=Off. The Off position explanation says "Noise Reduction will not activate when using a slow shutter speed". Does this setting accomplish what is desired to disable DFS? Or is this some other form of NR that is being enabled/disabled?

Likewise, MENU C2 item 14, "High-ISO Noise Reuction" has options: 1=Medium, 2=Low, 3=High, 4=Off. I am guessing that setting both of these options to Off would let you set the ISO as high as you wish (up to 12800) and exposure times as long as you wish without the inclusion of noise reduction. Again, maybe this is something OTHER than DFS?

I've only had my K-x for about a year, but until I retired a few months ago, I never had much free time, so I'm just now getting started with exploring astrophotography with it.

[miroshi]

Hi JohnT-W0JT,
I am a newbie in the photography but I tried some technics for night shots and:
if you are on bulb mode, you can not turn off Slow Shutter Speed NR. it is alaways on in bulb mode;
about High-ISO Noise Reuction, I think whene you choose between the three options the difference between them is (excluding the effect form NR) the time before you camera be ready for ne shot. So in this menu I use medium.

Best regards!

[freddykrueger]

Actually, you CAN turn off DFS in bulb mode. You just need to go to the debug menu (there's a topic about it somewhere here).

[cainmh]

I posted a8 lot of astro images taken with the Pentax K-x through an Orion 8" F4.9 reflector. All images were a combination of 30 sec exposures at ASA 12800

https://plus.google.com/u/0/photos/111606611049125551009/albums/5744667355515770193

Mike

[krp]

I posted a8 lot of astro images taken with the Pentax K-x through an Orion 8" F4.9 reflector. All images were a combination of 30 sec exposures at ASA 12800

https://plus.google.com/u/0/photos/111606611049125551009/albums/5744667355515770193

Mike

Wow, those are impressive. Makes me wish I had a good equatorial mount for my 8" dob. I believe the K-x forces DFS on long exposures with high iso's. Did you have to override that?

[cainmh]

No I kept the exposures to 30 seconds to prevent the noise reduction. I did some experiments on M42 early on and an exposure of 30 seconds at ASA 12800 brought out about the same amount of nebula detail as a 4 minute exposure at ASA 1600 (which takes 8 minutes to get!!). 30 seconds is also more foregiving for guiding. I typically took a dozen or more exposures and then I process them with AstroArt 5. I need to put more details on the photo page about how many exposures I combined etc. The 8" reflector is on an Atlas mount, on a steel pier, in an observatory in my back yard. Right now I am using the IR remote to take the images. I plan to experiment with a rubberband, C-clamp or some other device to keep the exposure button down. That way I could go in the house and do something while I automatically took pictures.

Mike

[krp]

No I kept the exposures to 30 seconds to prevent the noise reduction. I did some experiments on M42 early on and an exposure of 30 seconds at ASA 12800 brought out about the same amount of nebula detail as a 4 minute exposure at ASA 1600 (which takes 8 minutes to get!!). 30 seconds is also more foregiving for guiding. I typically took a dozen or more exposures and then I process them with AstroArt 5. I need to put more details on the photo page about how many exposures I combined etc. The 8" reflector is on an Atlas mount, on a steel pier, in an observatory in my back yard. Right now I am using the IR remote to take the images. I plan to experiment with a rubberband, C-clamp or some other device to keep the exposure button down. That way I could go in the house and do something while I automatically took pictures.

Mike

That is one thing that's annoying about the K-x, there's no way to use a cable release to hold the shutter down. What I did was bought one of these: Hot shoe adaptor and inserted a piece of metal that swings over to the shutter button where I attached a piece of rubber that holds it down. I use that to take startrail pictures.

[rawr]

The K-x IR remote has the option (I thought it was the default?) when using Bulb to operate thus:

one click - shutter opens
next click - shutter closes

It's under Customs Settings > 12: Remote Control in Bulb > Mode 1.

Combined with an IR Remote intervalometer like the neat GentLED-AUTO it offers the option of a walk-away solution to do a series of long exposures.

[cainmh]

That is one thing that's annoying about the K-x, there's no way to use a cable release to hold the shutter down. What I did was bought one of these: Hot shoe adaptor and inserted a piece of metal that swings over to the shutter button where I attached a piece of rubber that holds it down. I use that to take startrail pictures.

I ordered the hot shoe adaptor today.

Thanks for the idea.

Mike

[maxwolfie]

I am having some problems with my K-x in bulb mode with my intervalometer.

It seems that my intervalometer does not send another "pulse" at the end of an exposure to close the shutter, so Mode 1 (one click - shutter opens, next click - shutter closes) only allows a 30 sec exposure, 30 sec wait, 30 second exposure etc. This really isn't ideal for astrophotography as half the time is wasted.

In Mode 2 (hold to keep shutter open) it will only open the shutter momentarily because the IR unit only sends a pulse, not a toggle (or constant signal/pulse).

I am trying to expose for over 30 seconds. I've tried fiddling with the Delay, Interval and Exposure settings on the unit but it seems that no combination is going to make this work.

[tmmlrd]

Am I off topic if I report of my first astrophotos taken with my K100D Super (insted of K-x)?
If not, here they are (M57 planetary nebula and M13 globular cluster).
Pictures have been taken through my D=100 mm f/8 Newton telescope.
I used IRIS for elaboration although I'm not sure it manages PEF files correctly. On daylight pictures it results in "strange" colors. Is this normal with RAW pictures? If opened in Pentax Browser/Laboratory they seem ok...
Many thanks.

[cainmh]

Here is a link to more images I took with the Pentax K-X but through an 8" F4 Newtonian. I included a picture of the gizmo I made to continuously take images with the KX

https://plus.google.com/u/0/photos/111606611049125551009/albums/5889520775544970129

Mike Cain