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Author Topic: Anyone done medium format digital astrophotography?  (Read 3259 times)
Nstudio
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« on: June 02, 2013, 10:49:28 AM »
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Hey everyone. Im Planning my gear for an epic Yosemite sojourn and while there's apparently a notable moonrise that occurs over certain dome-themed rocks, I'm more interested in stars.   

I'm bringing a phase p+ series back and my hassy h1 but I'm wondering if I should consider bringing a cambo wide ds or some other such wide rig in order to get wider than a 35 hassy lens (h1 doesn't take the 28mm unfortch)... I imagine the wider the angle of the lens the longer one can expose without "making the jump to light speed" from earth's rotation...streakers.

Anybody have experience they wish to share on shooting medium format astrophotography? What about motorized tracking devices? My aim is to pack as little equipment and stay light weight as possible so I can roll deep into back country on foot...and make it back alive and whatnot I guess.

Excited for summer.
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David Campbell
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« Reply #1 on: June 02, 2013, 09:36:01 PM »
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Have not used my MF setup for astro photography as my back does not handle long exposure or high iso well, so I cant give you advice on that.
Seeing you want to stay mobile and pack light, perhaps the following may be of interest:

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

I chatted to a guy at the 2012 Solar Eclipse in Port Douglas that had one.
He was using a 600mm f4 telephoto and 1DsIII, so it can support a lot of mass for its compact size and weight.

Hope that helps
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NancyP
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« Reply #2 on: June 03, 2013, 11:51:16 AM »
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More options for tracking mount:
iOptron (tiny)
Vixen Polarie (tiny)
Astrotrac (light but long)
home-made Barn Door (Scotch) mount (heavier due to 3/4" plywood construction)
All need an extra ball head.
All mounts must be aligned to celestial North pole in order to function properly.
You don't need much precision for a wide angle.
Without a mount, your stars start getting stretched beyond 15 to 20 sec exposure. Experiment before you go on the trip.
Try hanging out on Cloudy Nights astrophotography forum, and DPReview astrophotography forum.
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Nstudio
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« Reply #3 on: June 03, 2013, 12:15:59 PM »
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Thanks so much!  great info. I've got over a month+ to prep so I'll sus out these equatorial mounts. In nyc/la/miami etc i'm accustomed to renting anything i dont own for jobs multiple times a week but i have never seen fotocare, adorama, k&m or trec or anywhere renting german equatorial mounts...probably a little obscure for the fashion/advertising world, eh? I'll check into those astrophotography/amateur-astrophysics fora. Unless you know of anyone in NYC who rents out equatorial mounts/polar scopes, etc etc. I have my doubts. I suppose I should brace myself for costs.

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theguywitha645d
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« Reply #4 on: June 03, 2013, 01:20:43 PM »
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I have used an AstroTrac and Polarie with my Pentax 645D. The Polarie I have not had a lot of time with--I sold my Astrotrac to purchase it. I have also use a Takahashi Sky Patrol (read expensive and heavier, but a great mount). iOpton Skytracker is a great deal. If you want high-end, then this is your guy:

http://www.toast-tech.com/en/

I switched to the Polarie because it is the most compact mount. The only thing I don't like is the polar scope is not illuminated, but shining a red LED flash light down the front works. But the scope is really well design where you simply dial in the data and time to find the relative position of Polaris.

With astrophotography, you are going to have to stop down for pin-point stars. Point sources are the hardest to get nice as they will show every limitation of your lens. Usually two stops is the sweet spot.

If you want round stars without a tracker, then you are right that the focal length is the limiting factor. Then how fast you can collect light is a problem. MFD is not the best solution for this--a 35mm sensor with good ISO 6400 is much better. The sensor + technology could help you here, I think you are still only at ISO800?

Dew with also be a factor. Your cameras can get wet. I use a cover over my camera. Focusing can be tough--it is dark at night. Bugs bug you and it can get cold standing around. Take some LLCs or flat-field exposures. There are lots of good resources on the web for wide-field astrophotography (but not with MFD equipment--the usual "advice! is it cannot be done, which is not true). If you go to the medium-format section of LuLa there is an astrophotography thread.
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markmullen
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« Reply #5 on: June 03, 2013, 06:33:28 PM »
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I'm sure you know but a handy guide is 600 divided by your 35mm focal length will give you a guide as to how many seconds exposure time before your stars begin to trail. Eg a 50mm lens would give you 12 seconds.
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NancyP
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« Reply #6 on: June 04, 2013, 10:10:29 AM »
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Try LensRentals:

http://www.lensrentals.com/rent/leica/support/tripods-monopods/tripod-heads/astrotrac-star-tracking-system

I would suggest finding a local astronomy club and seeing if anyone uses the astrotrac, and if so try to hang around for a demo on how to use it. And of course, you must know how to find Polaris and true celestial north, so get out your star chart and give it a gander.
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theguywitha645d
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« Reply #7 on: June 05, 2013, 09:34:40 AM »
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If you go to the Cloudy Nights forum, you can get more feedback on the iOptron Skytracker. There seems to be a positive response, but there have been some issues. A couple of folks have not been impressed with the periodic error--the ability to track smoothly. One has had a motor fail. This is a new mount and so some problems are expected, especially for a Chinese mount. BTW, this one reason I went with the Polarie as it is a Japanese mount built in Japan. Vixen has a good reputation. In my research, I did not find these issues with the Polarie, it just seemed to work. I had not read or experienced these problems with the Astrotrack either--made in the UK.
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snoleoprd
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« Reply #8 on: June 05, 2013, 03:10:06 PM »
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A lot of iOptron stuff is junk. They are cheaply made, but there are exceptions and sometimes there are good batches. The Astrotrac is usable, a bit more complex to setup but usable. I have an astrotrac as well as a couple of other trackers. I also have an observatory with a telescope and imaging system, so I have some experience but not with a medium format body and lenses. A dslr and dedicated cooled ccd cameras, yes lots of experience. A heavy camera and lens will need to be balanced carefully. The drive system will not carry a big load if is not balanced. There are different ways to do this, but most involve a counter balance of some sort. the Losmandy is well made. There is also some smaller more compact systems. You will need a good steady tripod, and geared head is the best way to align to the poles, a ball head can be used but it gets difficult to get it aligned accurately. If you are in Southern California I can help you get setup.

Alan
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Alan Smallbone
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Nstudio
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« Reply #9 on: June 06, 2013, 11:05:48 AM »
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A lot of iOptron stuff is junk. They are cheaply made, but there are exceptions and sometimes there are good batches. The Astrotrac is usable, a bit more complex to setup but usable. I have an astrotrac as well as a couple of other trackers. I also have an observatory with a telescope and imaging system, so I have some experience but not with a medium format body and lenses. A dslr and dedicated cooled ccd cameras, yes lots of experience. A heavy camera and lens will need to be balanced carefully. The drive system will not carry a big load if is not balanced. There are different ways to do this, but most involve a counter balance of some sort. the Losmandy is well made. There is also some smaller more compact systems. You will need a good steady tripod, and geared head is the best way to align to the poles, a ball head can be used but it gets difficult to get it aligned accurately. If you are in Southern California I can help you get setup.

Alan
Alan, I am interested in any help I can get. Sounds as though you know the ins and outs of what I'm looking to do and I am indeed in Southern ca.
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theguywitha645d
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« Reply #10 on: June 06, 2013, 09:57:44 PM »
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Well, a GEM needs a counter weight because of its design--and a GEM like a Losmandy G8 is not really a travel mount. An Astrotrac can easily handle a medium-format camera and the design needs no counter weight for that. An AstroTrac certainly is helped by a gear head for alignment, mostly because of its dimensions. I align my Polarie with a simple pan head.
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snoleoprd
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« Reply #11 on: June 07, 2013, 09:02:41 AM »
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Depending on the load and the weight even the Astrotrac will need a counterbalance, they also sell one:
http://www.astrotrac.com/Default.aspx?p=head

If you want to do anything other than a wide angle view then you might need a way of balancing. Especially with telephoto lenses which can create larger moment arms. The Polarie is great with light loads and wide angles, but put anything with some weight on it can be an issue, but I tend to use these trackers with wide angles, then the polar alignment is less critical. The Polarie is nice.

Alan
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Alan Smallbone
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theguywitha645d
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« Reply #12 on: June 07, 2013, 11:28:11 AM »
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I never needed a counter weight with my Astrotrac with a medium-format digital camera and focal length up to 120mm @ 5 min.--I never tried anything longer. The Astrotrac site posts images taken through a 600mm Televue scope on the basic mount. The balance arm on the Astrotrac is more about pointing large optics than being able to carry them--there are parts of the sky you would not be able to point a camera/telescope with just a ball head on the Astrotrac (an arm and counter weight is not going to make it more stable). The complete AstroTrac setup with counter weight might be transportable, but not really portable. (My astro friends travel with their gear, but never more than 10 feet from their car. Wink )

The Polarie is relatively new to me and the weather has not been great. But the reviews and results I have seen should allow me to use my 645D with focal lengths up to 120mm. I will know more as I play with it. A few folks have designed counter weights for it, but I have seen other simpler solution with gimbal heads. The 645D has the advantage of two tripod sockets which makes positioning the camera easier.
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