Pentax 645z Astrophotography Using the iOptron SkyTracker

[Torbjörn Tapani]

Nice article!

I have the same iOptron Skytracker v2 which I use with my D800E. One thing that bugs me that I havent resolved yet is the ballhead mounted on the Skytracker. I think the ballhead would be better turned upside down. You almost always end up wanting to point the camera in a direction where the dropslot will be in the wrong orientation. You will want to have the pan base under the quick release. I think a Novoflex Magic ball could work better than a regular ballhead as well. This problem is made worse for me at a highter latitude (65-67 degrees north!). Ballheads are just not designed to be mounted almost vertically

[michael]

The drop-slot on the Acratech can rotate 180 degrees, so this isn't a problem with that head.

Michael

Show us some of your AstraTrack images.

[Torbjörn Tapani]

Not much to show. First thing I tried last year was a stack of the Andromeda galaxy. 70-200/2.8 at f/4, 30 seconds ISO 800.

But my main use would be astroscapes like in the second image. One exposure with foreground and one with tracker for the sky.

[michael]

Andromeda is high on my list. Regrettably we've now have had 10 cloudy nights in a row, and a full moon for the next little while.

Damn moon.

Michael

[Jonathan Ratzlaff]

The andromeda galaxy is good to play with on a dark night.  This one was 15 stacked images plus dark images.  A really dark sky would also be nice.  This was taken and around 9:00 PM and Andromeda was still fairly low in the sky and competing with the lights of Kelowna.  The image was processed in image stacker from raw files (D90) and the resulting 32 bit file processed in PS.  Night time photography brings out the worst in your lenses, hence the haze.
When using my star tracker I try to ensure that the tripod base is as level as possible.  I use the bubble level on the smart phone to level it. There is also a program called polarfinder that helps you locate polaris in the polar scope according to the time of day.  This makes tracking much more accurate.  So with an 80-200@200mm, with 25 second exposures, there was little movement between frames


The other image is best taken with a fast lens  4000 ISO 14mm 2.8 20 sec with a D7100.  Not as good as a full frame but not bad compared to other cameras.  A judicious use of a gradient filter in lightroom keeps the campfire in the foreground in check.  

[laughingbear]

Hi,

I find this market is served with many options for entry level tracking systems in that price range. Personally, I would find it difficult to make a choice here. 

Here are just a few examples starting with the iOPtron Sky Tracker.:

https://www.ioptron.com/index.cfm?select=productdetails&phid=6b0da2fb-2294-4805-bdcb-e534af12c1e2

http://www.astrotrac.com/Default.aspx?p=tt320x-ag

http://www.losmandy.com/starlapse.html

http://www.vixenoptics.com/mounts/polarie.html

[Torbjörn Tapani]

When I got my tracker I compared the same systems. The first really compact tracker was the Vixen Polarie and it is very similar to the iOptron Skytracker in shape and design but require an additional head and polar scope is optional (more $$$). With the Skytracker you have the geared wedge built in and it comes with polar scope. The Skytracker has only one speed (two directions for north and south hemisphere). The Vixen Polarie has some extra settings for tracking sky, moon, sun and so on. This could be useful if you plan on using it as a simple pan head for a timelapse.

The Astrotrac is probably more sturdy with higher load capacity and very accurate tracking. You have to reset the screw that turns the arm after 2 hours and it seemed a little less compact to me.

The Losmandy starlapse is basically half a equatorial mount with the same part as their telescope mounts. Weight goes up but it can be operated like a GOTO bascially and if you buy the other half it is a complete mount. Too heavy and cumbersome to bring along all the time. I think you would be better served getting a complete mount for a small telescope, probably cheaper as well.

Edit: actually the SkyTracker has two speed settings. Sidereal rate and 1/2 sidereal if you accept some smearing of both sky and ground objects. Maybe good for 30 sec on a very wide lens. I don't use it.

[BernardLanguillier]

The Astrotac seems to be a pretty appealing option as well. The learning curve seems a bit steeper from a quick read of comments online though.

All that is very tempting... just need to find clera and dark skies.

Cheers,
Bernard

[NancyP]

Astrotrac is bulky, but if you are diligent about setting up, you can get reasonably good results with a 400mm lens at 1 minute the very first time I set up the Astrotrac - I was floored. I hadn't really meant to do anything seriously at 400mm but I wanted to see what the Astrotrac could do, and was impressed to get "round stars". Admittedly, I was very fussy about setting declination as best I could, and setting up Polaris within the Astrotrac sight accessory (highly recommended - setting up by eye could be a PITA).

[NancyP]

I feel Michael's pain concerning clear dark skies. We have good dark skies about 2.5 hours away in the middle of the National Forests and Wilderness Areas in the Ozarks, but we don't have great weather in Missouri. Here's a low-res photo for a screen show, non-tracked, stars layer at 21mm f/2.8 20 sec ISO3200, from an ancient volcanic elevation about 300 feet above its surroundings - good dark sky for 90 min drive from town. The rocks were light-painted and layers merged. The rocks are igneous and are about 1.6 billion years old, the cracking makes the "mountain" look like a big brickyard,  once called "Devil's Honeycomb" (see "Devil's Causeway" in Ireland for same phenomenon of cracking while cooling down).

[BernardLanguillier]

I feel Michael's pain concerning clear dark skies. We have good dark skies about 2.5 hours away in the middle of the National Forests and Wilderness Areas in the Ozarks, but we don't have great weather in Missouri. Here's a low-res photo for a screen show, non-tracked, stars layer at 21mm f/2.8 20 sec ISO3200, from an ancient volcanic elevation about 300 feet above its surroundings - good dark sky for 90 min drive from town. The rocks were light-painted and layers merged. The rocks are igneous and are about 1.6 billion years old, the cracking makes the "mountain" look like a big brickyard,  once called "Devil's Honeycomb" (see "Devil's Causeway" in Ireland for same phenomenon of cracking while cooling down).

I have just opted for the Astrotrac. We'll see what we get.

Your (otherwise very nice) image tells me that merging the sky with the landscape below it is probably one of the 2 major challenges here.

Cheers,
Bernard

[NancyP]

Yep, my first attempt at layers in Photoshop, so it's crude, to say the least.      I have to get out of the Lightroom rut someday.... I figure that this image pair will be good for some more learning - which is why I love photography, something new to learn every day.

http://mdc.mo.gov/discover-nature/places-go/natural-areas/hughes-mountain

[BernardLanguillier]

Yep, my first attempt at layers in Photoshop, so it's crude, to say the least.      I have to get out of the Lightroom rut someday.... I figure that this image pair will be good for some more learning - which is why I love photography, something new to learn every day.

Indeed, photography is a moving target. The scope of the images that be created is pretty much limited only by our own mind.

Cheers,
Bernard

[laughingbear]

I lean towards the astrotrack as well. Of course all these entry level systems have several limitations, but for nightscapes they seem to work just fine.

Achieving stars without the "egg look" at 400mm sounds very good Nancy!

As for clear skies, and for you folks in Canada/US and Mexico this tool here looks useful.

http://cleardarksky.com/csk/index.html#chart_list

Plenty of data available, such as Algonquin Michael. 

http://cleardarksky.com/c/AROONkey.html?1

[Bart_van_der_Wolf]

I have just opted for the Astrotrac. We'll see what we get.

Hi Bernard,

Looking forward to your findings.

I have had my eye on that one as well, for a long time. It's just that the local seeing conditions are terrible in one of the most light polluted countries in the world, and that's where I happen to be located.

Cheers,
Bart

[BernardLanguillier]

Hi Bernard,

Looking forward to your findings.

I have had my eye on that one as well, for a long time. It's just that the local seeing conditions are terrible in one of the most light polluted countries in the world, and that's where I happen to be located.

That's indeed going to be the problem.

There are places in Japan with very little light pollution, but winter time is probably the best and those get pretty cold at night (rarely warmer than -10C).

Cheers,
Bernard

[NancyP]

cleardarksky is invaluable for sites in North America. I would think that the astronomical societies in Japan would have good local information about sites with astronomical seeing reports.

[afriedl]

Some of the user reviews for the iOptron SkyTracker are less than laudatory on the vendor sites. Folks complain mainly about sub-par built quality and lack of attention to detail requiring user modifications to gain stability. How do the users here feel about this? I am trying to make a decision between the Vixen Polarie and the Skytracker. Thanks...

[DaveCurtis]

Another option with these small tracking mounts is to purchase an astro camera and couple to a camera lens.

The advantage being you had record H-alpha light more efficiently and the camera is cooled.

The attached image is of the Rho Ophiuchi comples around  Antares.

Camera: QHY 8L running at -30C. Stacked  8 exposures @ 5minutes each plus calibration images (flats, darks and bias)

I was using my Zeiss 135mm APO @ f2.8.

[laughingbear]

Another option with these small tracking mounts is to purchase an astro camera and couple to a camera lens.

The advantage being you had record H-alpha light more efficiently and the camera is cooled.

The attached image is of the Rho Ophiuchi comples around  Antares.

Camera: QHY 8L running at -30C. Stacked  8 exposures @ 5minutes each plus calibration images (flats, darks and bias)

I was using my Zeiss 135mm APO @ f2.8.

Beautiful Dave! That is really an interesting option you shared here.

Did you use a narrow band 12nm filter?