Pentax 645z Astrophotography Using the iOptron SkyTracker

[BernardLanguillier]

I agree there is a learning curve involved, and practice makes perfect, but there will remain to be challenges. No visibility on Polaris is a big issue, but then we may also combine/composite two images. One image with attractive foreground, and one with unobstructed sky (from a nearby location if we want to stay true to the truth).

Actually getting the images in the first place is obviously the first step of creating beautiful final images, it's a process.

Bart,

Thanks, I am starting to get a feel for the kind of commitment it requires.

It can definitely not be an after thought. The logistics of the whole trip must be managed taking into account the additional opportunity to capture such night images and the identification of shooting locales must take into account that extra constraint which is clear view to the North.

Sounds like fun!  

You raise an interesting philosophical point about the truthness of such image assembling techniques. Being a stitcher, I have no morale problems with composing images from sub frames, but assembling 2 parts of an image captured from different locations (albeit possibly close) is something I have never considered doing. But the again, why not indeed?

Regards,
Bernard
 

[michael]

Though I haven't written anything about it yet, I have become immersed the passed few weeks in astrophotography. While the iOptron is great for travel, I got the hots for something more substantial. I've since bought a Vixen SXD2 German Equatorial mount with Skybook 10.

A week of overcast skies and rain has prevented any serious work, but today promises the beginning of several days and nights of clear skies.

By the way, the learning curve on doing serious astronomic photography is very steep. But I'm enjoying climbing the hill.

I'll be writing all about it eventually.

Michael

[Bart_van_der_Wolf]

Though I haven't written anything about it yet, I have become immersed the passed few weeks in astrophotography. While the iOptron is great for travel, I got the hots for something more substantial. I've since bought a Vixen SXD2 German Equatorial mount with Skybook 10.

Wow, that's really something else than simply convenient for travel... On the other hand, with a load capacity of up to 50 pounds (including counterweights), you can use several cameras at the same time ..., as in stitched starry skies. A good stitcher can handle different focal lengths, so you do not need to match lenses (or even cameras) and parallax is not an issue at infinity.

A week of overcast skies and rain has prevented any serious work, but today promises the beginning of several days and nights of clear skies.

I hope you have clear skies and pleasant temperatures (also to avoid condensation).

By the way, the learning curve on doing serious astronomic photography is very steep. But I'm enjoying climbing the hill.

I'll be writing all about it eventually.

Enjoy the climb, I'm sure you will. Looking forward to reading about your findings.

It's one of those wonderful photographic subjects that allow us to better record things that we can hardly observe real time with our eyes. Pupil dilation will bring out the worst aberrations that our eyes have to offer, and sensitivity shifts to mostly luminance and color gets shifted to shorter wavelengths for the limited colors that we can still see.

Cheers,
Bart

[NancyP]

Re: dew - first, use your lens hood. Next purchase, Michael, might be an anti-dew heater of some sort. There are ready-made solutions, essentially strips of modestly resistive covered wiring ("electric blanket") that wrap around the optical tube assembly and attach to a regulator and battery. You can make your own from plans on the internet and some odds and ends from Radio Shack. For camera lenses, you can improvise by wrapping one of those chemical hand-warmer packets around your lens - I haven't tried this yet, but plan to, because this is a really portable solution.

http://www.optcorp.com/telescope-accessories/dew-solutions-telescope-cooling/dew-controllers-heater-straps.html (for example)

[DaveCurtis]

While you're at Optcorp just get one of these http://www.optcorp.com/asa-800mm-ritchey-chretien-alt-az-telescope-nasmyth-focus-image-rotator.html   

[Alan Smallbone]

As someone who has done a lot of astrophotography over the years and also led several workshops, especially for beginners. It is the most difficult and frustrating type of photography to do. Also the equipment needed to do it well is also quite expensive. Michael will start on the madness of guiding soon, and that will lead to a large learning curve. Then cooled astronomy cameras are the next thing..... Setup needs to be done very accurately and signals are very low, compared to daylight photography.

Here is an image of mine from about 5 years ago, taken with a refractor at 420mm focal length f3.9, taken with an 11mp cooled ccd full frame camera, cooled to -20C, about 12.5 hours of exposure time, using 10 minute sub exposures through luminance, red, green, and blue filters, took 3 nights to get the full 12.5 hours of exposure time.
http://apod.nasa.gov/apod/ap090211.html

Each frame has to be downloaded after exposure, that takes about 50secs per image, resulting in a 16bit fits files, which then needs dark, bias, and flat frames subtracted. Then it all needs to be aligned, data rejection needs to be done(removal of spurious signals, like gamma ray hits, satellites, planes, etc.) then stacked and then processed as a color image and then edited.

The Orion nebula area has a large number of geosynchronous satellites that streak through the image, along with planes, etc.

A frustrating hobby but can be rewarding when everything works. Best advice, stay widefield, tracking requirements are lot less.

Alan

[Torbjörn Tapani]

That's a very nice image Alan. It got me thinking. Has the field changed much in the last 5 years since that image? Meaning for the same level of investment in gear can you get different results today?

[Alan Smallbone]

That's a very nice image Alan. It got me thinking. Has the field changed much in the last 5 years since that image? Meaning for the same level of investment in gear can you get different results today?

Thanks, the field has not changed a lot. There are some better high end mounts, but the prices are up there. Prices have gone up a lot. Some of the top of the line mounts are bordering on $15K and higher, scopes are higher because production costs are higher. I used a 5" refractor on that image, that I still use, and for a apochromatic is still north of $5k. As for cameras, there are bigger sensors but then few scopes have corrected image circles large enough and the ones that do are in the $10-30K and higher. You still face bigger problems with seeing conditions, the atmosphere is a huge issue, some nights the seeing is really bad and some nights it is good. Filter technology has not really changed, but bigger sensors require much larger filters. Narrow band filters are really expensive especially in large sizes. The two cameras I have, one is an 11mp full frame, and the other is a 8.3mp apsc sized sensor. There are some AO type devices on the market but they do not correct for seeing, they will correct of mount imperfections. Until we can generate our own guide stars and have truly bendable optics AO type devices are not really worth it except for cleaning up the mount.
The reality is there is not a tremendous amount that has changed in the last 5 years. Some change but not a lot and gotten more expensive.
It is a hobby that can make medium format photography seem inexpensive..... 

Alan

[Torbjörn Tapani]

Ok thanks. So basically we are limited by seeing. So one could get used gear and still be doing OK. Something I'm interested in, someday.

[michael]

While you're at Optcorp just get one of these http://www.optcorp.com/asa-800mm-ritchey-chretien-alt-az-telescope-nasmyth-focus-image-rotator.html   

Looks like just the thing, except in won't fit inside the rear hatch of my Jeep.

Michael

[michael]

Alan,

Thanks for your comments. Really lovely image in your link by the way. Congratulations!

I had a complete astro imaging setup about 15 years ago, when I had a cottage at a dark sky site in Northern Ontario. An 8" SCT, and SBIG CCD camera, filter wheel etc, all the toys.

But, ultimately I gave up. These were the days before DSLRs and GOTO scopes, and between the long set up times, need for a computer, mosquitoes, cold etc, etc I called it quits.

Now I have a country site, that while not as dark as Muskoka, still shows the Milky Way from almost the horizon to almost the horizon. There are two large towns about 20 miles to the north and 30 miles to the east which do cause some light pollution, but it's still pretty good.

There are almost no mosquitoes here because it is farm land, not forest...so much more tolerable.

The Vixen SXD2 with Starbook 10 is turning out to be a great choice for me. Light enough to carry outside if I feel like working for a few hours, yet rated to carry up to 50lbs. I'm mainly working with my Pentax 645z and lenses, and doing deep sky work, so that's not really an issue.

I'm doing 30 to 40 30-second stacks and getting excellent tracking. I have yet to do a PEC, though will the next good night.

I'm using Nebulosity3, which works well, though it has a bit of a learning curve (what doesn't)? I chose it because I'm on a Mac, and most other astro stacking programs are Windows only.

Yes, I have been bitten by the auto-guider bug. Again, there is an accessory board for the Starbook that takes an input from a guide scope / CCD, and so a computer isn't needed. The board and the guide scope/camera come to a bit over $1K, but I'm sorely tempted. First I have to get an external intervalometer (this week), because the Pentax 645z only allows automatic sequence shooting of 30 seconds max. My tracking at the moment is good enough for about 1 minute exposures at 400mm and obviously much longer at shorter focal lengths.

What's nice about stacking is that I can get a sequence going and then go in for dinner while it does its thing. I do my darks at the end of the evening while I'm tearing down, and the flats the next morning.

Lots of fun, and lots to learn, which is one of the things that I enjoy very much.

I'm working on an article that will describe my journey to date, and hope to have it online in a week or two.

Michael

[Fine_Art]

First attempt this Sunday with the Astrotrac TT-320X-AG.



I found locating Polaris easier than I thought it would be thanks to the iPhone app Starmap Pro. It did validate what I thought was Polaris and made the whole experience less "stressful".

I found it a bit challenging to adjust the position of Polaris in the Polar scope with my RRS large ball head, but it can be done.

I used the Sigma 35mm f1.4 Art at 2.8 on the D800. With a 4 mins exposure at ISO 1600 I don't see much of a trail behind stars, so things seem to work fairly well. Beginner's luck I guess.

Cheers,
Bernard

It looks good.

You might find a conditions chart like the following handy, even for regular photography.
http://cleardarksky.com/c/Calgarykey.html?1

The seeing conditions also impact far off mountains. I usually check the chart for the region I am shooting in. I try to go when conditions are good.

[Alan Smallbone]

Alan,

Thanks for your comments. Really lovely image in your link by the way. Congratulations!

I had a complete astro imaging setup about 15 years ago, when I had a cottage at a dark sky site in Northern Ontario. An 8" SCT, and SBIG CCD camera, filter wheel etc, all the toys.

...

Lots of fun, and lots to learn, which is one of the things that I enjoy very much.

I'm working on an article that will describe my journey to date, and hope to have it online in a week or two.

Michael

Thanks a lot Michael, sounds like you are having fun and I look forward to reading about your exploits. I am lucky in that I belong to a club that has a dark sky site about 80 miles from where I live. I have an observatory and warming room there, so my equipment is setup on a permanent pier, all I have to do is roll the roof off and turn everything on. I can control it all from my warming room and have a place to stay warm during the winter and sleep and have a/c during the summer. It is at an altitude of 5000feet in the high desert environment, near Mt. Palomar, we get hot summer rains with lighting and an occasional bit of snow in the winter.

I have an Astrotrac, and a Vixen Polarie and I have used the Ioptron tracker. The Astrotrac I have their portable pier system and everything fits inside the pier for easy transport, it has by far the best tracking of the small portable units. The next best is the Polarie, the Ioptron had the worst periodic error of any of them. But is sounds like you are well on your way to more madness. 

Best of luck for your future astrophotography adventures.

Alan

[BernardLanguillier]

I am lucky in that I belong to a club that has a dark sky site about 80 miles from where I live. I have an observatory and warming room there, so my equipment is setup on a permanent pier, all I have to do is roll the roof off and turn everything on. I can control it all from my warming room and have a place to stay warm during the winter and sleep and have a/c during the summer. It is at an altitude of 5000feet in the high desert environment...

Way cool Alan, I am jalous!

I would guess you have one of those high end Italian espresso machines as well?

Cheers,
Bernard

[Alan Smallbone]

Way cool Alan, I am jalous!

I would guess you have one of those high end Italian espresso machines as well?

Cheers,
Bernard

Ha! I can't afford it after the astronomy gear...... 

Alan

[NancyP]

And then there are the UNFORESEEN problems......

I went to a likely site to do some astrolandscape shooting, also to experiment with some light painting. Hour and a half drive, perfect clear no-moon night, somewhat picky hike in, and I hiked the whole loop and backtracked to the best site around sunset. Found one person sitting there, I quietly set up tripod a few rocks away, he got up in a huff and moved off. Fine. Well, I am hanging around for about an hour waiting for the true dark, and just about the time that it is dark enough to start seeing decent number of stars, I hear someone yelling help, and noone else responding. So after a bit of yelling back and forth to find out what was up, it turns out that Grumpy had gotten himself lost. Because this location is a forest with complicated slot canyon and trees growing to the edge of the dropoff in a few places, I was concerned that he could make a disastrous mis-step, so I packed up and went down the trail towards the voice. I found an apologetic Grumpy at the edge of a safely descendable slope, and walked back to the parking lot with him. I didn't go back to the light-painting venue due to having found that my second light source had failed and I didn't have spare batteries on hand, just the single headlamp, so I just settled in a somewhat boring pine glade close to the parking lot, skipped the light painting (trees? meh), and had fun photographing. I think that the site is  "green" on a Bortle dark scale, so I will be back with a large handful of extra headlamp and flashlight batteries.

[Telecaster]

I never do astro-pic-taking without also having a pair of binoculars handy. IMO there's at least as much enjoyment to be had from real-time direct observation as from the photos. My suggestion to anyone getting started with this stuff is to not over-complicate it.…keep it simple until you feel compelled to get more in-depth.

-Dave-

[NancyP]

Yep, I like using my SkySafari phone app in red mode to get better at recognizing constellations quickly, it has a gyro function that aligns the star map in the direction you are pointing your phone. Is it possible to see Andromeda galaxy with the naked eye "straight on"? I tell myself I see something in the place where it ought to be "from the corner of my eye". I am starting big, with naked-eye observation and occasional 7x binocular use. GoTo scopes are all very well, but something in me just wants to start the old-fashioned way.

[michael]

Binoculars are definitely a good start.

Always keep things simple in the beginning. Except if you're me, who dives in with both feet. 

[sdwilsonsct]

Is it possible to see Andromeda galaxy with the naked eye "straight on"? I tell myself I see something in the place where it ought to be "from the corner of my eye".

Yes it is, but your eyes need to be dark-adapted.  It might be necessary to put the phone down for a while.