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Shooting Milky Way shots with the 50mp CMOS backs

Don Libby

Well-known member
I've been experimenting piggybacking off a 6" telescope with tracking using both a Sony A7rII and my XF/IQ180. The camera piggybacks on top of the scope and provides a very stable base to shoot from. Sadly I've only been able to use it here in Tucson with light pollution however it looks good (I should have more within a week or so).

We just returned from Mexican Hat UT where there was an over abundance of dark skies and used a Vixen Optics Polarie Star Tracker with the Sony A7r II with great results. The Polarie is similar to the iOptron with a smaller payload.

Don
 
Graham, care to share your thoughts on the iOptron tracker? I weighed my 28, XF and IQ and came up with 7.2 pounds which looks to be about 1/2 a pounder the weight limit. How difficult was it to set up? Any other thoughts would be appreciated.

Don
You are picking the wrong tool for the job. With 28mm f4.5 wide open you would need to track the sky for something like ISO 3200 and 150 seconds, or equivalently ISO 35 and 3.8 hours. Given that the weather can change fast and cloud can move in, and that the sun rises in just a few hours time, realistically a CCD digital back like the IQ180 is not going to do the job for you, as high ISO / long exposure is the worst use case, and it's nearly impossible for you to shoot any darkframe with the battery you carry, and the timeline is not practical for you to maintain the humidity and temperature.

Even if you can successfully track the sky, you would have a hard time dealing with complicated foreground for composition in Photoshop. (And good luck with shooting the even darker foreground when it's far beyond your light's reach.)

Even a cheapo APSC kit like Nikon D3300 ($550) + Tokina 11-16mm f2.8 ($450) can do a much better job than your medium format CCD gear shooting the Milky Way.
 

GrahamWelland

Subscriber & Workshop Member
Graham, care to share your thoughts on the iOptron tracker? I weighed my 28, XF and IQ and came up with 7.2 pounds which looks to be about 1/2 a pounder the weight limit. How difficult was it to set up? Any other thoughts would be appreciated.

Don
Don, I had no problems using a D4 head on the StarTracker with XF, IQ150 and 28D on it. I don't think that I'd go much heavier but it seemed to work just fine. Next time I'd use something lighter like an Acratech or ball head to make adjustments of the camera easier.

Set up is relatively easy so long as you do it early just after civil twilight or even the beginning of astronomical twilight but before total darkness if the sky is full. You need to align the StartTracker with the pole star and apply an offset based on your lat/long/time etc which iOptron's app will tell you. You can use the small hole in the StarTracker to crudely align with polaris and then use the scope to align more accurately and to move polaris to the correct offset position on the projected grid.

The unit is probably good for 3-4 minutes of powered rotation with this set up to avoid any slight tracking of the stars.

Hope that helps.

You are picking the wrong tool for the job.
Well, if all you want to take with you is your Phase One XF & back, who is to say that it is 'wrong'? Sure there are EASIER systems to use but if you only want to travel with a single system this outfit gives you that option.
 

Don Libby

Well-known member
Don, I had no problems using a D4 head on the StarTracker with XF, IQ150 and 28D on it. I don't think that I'd go much heavier but it seemed to work just fine. Next time I'd use something lighter like an Acratech or ball head to make adjustments of the camera easier.

Set up is relatively easy so long as you do it early just after civil twilight or even the beginning of astronomical twilight but before total darkness if the sky is full. You need to align the StartTracker with the pole star and apply an offset based on your lat/long/time etc which iOptron's app will tell you. You can use the small hole in the StarTracker to crudely align with polaris and then use the scope to align more accurately and to move polaris to the correct offset position on the projected grid.

The unit is probably good for 3-4 minutes of powered rotation with this set up to avoid any slight tracking of the stars.

Hope that helps.

Thanks for the info Graham. I've been experimenting with piggybacking both the XF and A7rII sitting on top of a Celestron Advanced VX 6" telescope. This system has both a guide camera as well as auto goto functions and while it handles the weight of either system very well it requires 4-large Pelican cases and fully assembled weighs north of 35 pounds. The good news is I can capture at lower ISO for longer times and use any of my P1 lenses. I now have the iOptron Skytracker (Sandy calls it the Graham tracker) and it seems to be a very convenient travel package. I've weighed the XF with the 35mm and found it weighs in as over 8 lbs so that means the 40-80 and 75-150 will also be too heavy. Luckily enough I also have the 28 and just picked up a 200 APO (at SK Grimes getting the mounting fixed).

Currently I can choose between the Celestron (I'll try and get an image of the setup posted soon) that can handle just about any weight I put on it and the iOptron that can handle 2-lens on the XF or anything on the Sony. Weight issues aside, I can go several minutes with the Celestron. The Celestron is slated for ground travel and the iOptron air.



Well, if all you want to take with you is your Phase One XF & back, who is to say that it is 'wrong'? Sure there are EASIER systems to use but if you only want to travel with a single system this outfit gives you that option.
There really isn't such a thing as the "wrong camera" so long as you have one and know the limitations. I currently use 2-systems, Phase One IQ180 which has its limitation for this application and a Sony A7r II which with the proper lenses rocks (I've taken great single image files as low as 8-seconds with ISO 4000 and f/0.95. I should be getting a CCD camera for the Celestron next year for deep space imaging.

Anyway thanks for the information.

Don
 
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Well, if all you want to take with you is your Phase One XF & back, who is to say that it is 'wrong'? Sure there are EASIER systems to use but if you only want to travel with a single system this outfit gives you that option.
But in addition to a Phase One system, a Nikon D3300 is surely much lighter and smaller than a tracking mount system :grin: Unless you're using a CMOS digital back, you're not gonna achieve better results with a CCD back with a tracking mount than a Nikon D3300 without a tracking mount.

This is also one reason why I tend to sell off medium format gear - One 35mm format system is good enough for almost every aspect of work and is portable for whatever journey I'd like. Who knows how many years the IQ3 100MP will last.. Perhaps as lucky as the IQ180 for 5 years (but had been good at dynamic range for only 1 year before D800E was released), or as unlucky as the P65+ for 3 years. Technology advancement eventually washes away the image quality advantages - and what's leftover would just be the contents of the photos. Wanna do fancy Milky Way landscape? CCD is out of the game. Wanna do fancy backlight long exposure landscape? CCD is out of the game. Wanna get creative capture from a different point of view? Sorry the much smaller sensors carried by the cheapo DJI drones do a much better job than those medium format cameras sitting on classical and well-photographed iconic sites.

There really isn't such a thing as the "wrong camera" so long as you have one and know the limitations.
Really? IQ180 is not a wrong choice for Milky Way landscape? Well I hope you've got a clue of whatever you plan to shoot and good luck with that. :scry:
 

modator

Member
Hi Graham,

I follow this thread since the beginning as I was interested too about making a milky way photo from the mountains of my region, finally I've choose to use the HCD-28mm @ F4, ISO 6400, and exposures of 32 to 45s, without a star tracking mount or other device.
To get a high portion of the sky above I opted to shot portrait making a multi shot collage at home using PTGUI pro, here's the result :



Using 45s I found the milky way have more color detail and the star trails are very limited as the maximum time to use is around 23s considering the relative focal length (45 is the double, and a little trail is present but acceptable (also for large prints).

Enjoy, Domenico.
 

GrahamWelland

Subscriber & Workshop Member
Nice job! :thumbs:

Id be interested in seeing how much tracking you saw as I have to shoot under 20s even on my Sony a7rii to avoid trailing stars.
 

Paul2660

Well-known member
Great shot for sure. I would love to get to a spot where the Milky Way is laid out horizontally, but in my locals it's almost always vertical or on a vertical layout.

I am also surprised at 45 seconds, that you don't have a optical blur issue since for exposures that long the stars will trail and be in sharp focus and the milky way will also move but as a mass and is blurred a bit, so your eyes look to the star trails and the milky way seems harder to view at 100% or printed. But it worked and looks great for sure.

I have also wondered how PtGui would handle a scene like this, looks like it had no problems, good to know.

Paul C
 

modator

Member
Nice job! :thumbs:

Id be interested in seeing how much tracking you saw as I have to shoot under 20s even on my Sony a7rii to avoid trailing stars.

Well Graham,
as I told before a little trail is present (around 12pixel) , but considering that the final image is 15000x7500, if printed at 300dpi it become 127x63 cm wide (that's very huge) the 12px trail length at 300dpi is only 1,02 mm !! if You print at higher res of half size You get even better result reducing also the overall noise of the image.

here's a crop at 100% of the center of the milky way (wheres it's almost horizontal).


I've made the crop directly from Phocus v3.0.2 without any improvement such as Sharpening or Noise Filter, everything checked out to send the raw files to PTGUI for the stitching.

Enjoy, Domenico.
 
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