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Archive 2014 · Sony A7r for Star Trails?

  
 
WayneTk
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p.1 #1 · p.1 #1 · Sony A7r for Star Trails?


Please forgive me if this topic has been covered in the huge A7/r/s photos thread but I was wondering if anyone has used the A7r for star trails.

I have a D800E now but would like to use the Canon 17TSE so when I shoot over old churches or barns I can keep the building's angles straight.

Is the battery performance good enough for a 2-3 hour collection of 30 second images? Is the remote cord reliable enough? Any problems focusing in near darkness a problem without an optical viewfinder? Other concerns or observations would be of help.

Thanks



Jul 24, 2014 at 07:18 PM
dgdg
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p.1 #2 · p.1 #2 · Sony A7r for Star Trails?


I have done some long exposure tracked images at night with an A7 which is probably relevant enough for you.

After taking about 10 lights (and accidentally 10 in camera darks) over the span of an hour, I then took 10 darks for 30 minutes in the trunk of my car on the way home, and lastly 10 quick bias frames in the driveway on a fully charged battery in 70 degree F weather. I turned on electronic first curtain.

At that point battery life was 37% for a little over 1.5 hours of total exposure time, verified by my image file date/time info on my computer. So I would think in warm weather, you could probably squeak by on a good fully charged battery for about 2 hours. In cold weather, probably not nearly as good. You may want to look into the ac/dc power supply for the A7r or change out the batteries really quickly.

I forgot to turn off long exposure noise reduction so each light was followed by an equal exposure for the in camera dark frame. Hence, I could have had 20 lights instead. I have since turned off the long exposure reduction feature since I stack in post. This is probably even more important for star trails to avoid gaps in the trails. I don't know how long the exposure has to be before it starts taking in camera darks.

I have a third party wired intervalometer that works fine for any exposure length I set. I imagine any wired release would work

I never use an optical viewfinder for focusing. With Canon, I use magnified live view on a bright star. With the A7, LCD screen 'live view' magnified manual focusing is great as long as you turn off the peaking feature. Just be sure to tape down the focus ring carefully. You may want to set up everything at home and save your settings as a custom mode so you don't have to fiddle with it in the dark.

I seem to be the only one that goes on and on about dew, but if you are out all night and pass the dew point, your affected images will be ruined. I've been burned once, but never again. Only time I have not passed the dew point was at Arches NP. I have a small dew heater strap that I apply after taping the focus ring securely. I use a cheap jump start battery to power the dew heater controller. My camera strap may literally drip from moisture but my glass stays perfectly clear. A 15" strap should cover you for all your lenses.
http://www.thousandoaksoptical.com/dew.html

David



Jul 24, 2014 at 10:41 PM
bwana999
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p.1 #3 · p.1 #3 · Sony A7r for Star Trails?


WayneTk wrote:
Please forgive me if this topic has been covered in the huge A7/r/s photos thread but I was wondering if anyone has used the A7r for star trails.

I have a D800E now but would like to use the Canon 17TSE so when I shoot over old churches or barns I can keep the building's angles straight.

Is the battery performance good enough for a 2-3 hour collection of 30 second images? Is the remote cord reliable enough? Any problems focusing in near darkness a problem without an optical viewfinder? Other concerns or observations would be of help.

Thanks


I've used the A7R and A7S for star trails, astrophotography and nightscape photography with good success. A few comments:

1) The electronic viewfinder I find to be far superior to an optical viewfinder for focusing and framing.

2) I normally use Focus Peaking to get a focus and have checked this approach against using a Bahtinov mask. Both work well. You can also simply focus until you get the most stars displayed in the viewfinder or on the liveview screen.
2a) I find it helps to up the ISO and exposure while getting a good focus and framing.

3) Battery life is about 2 hours. If I'm shooting sessions longer than this I use a 110 volt adapter.

4) For multiple imaging sessions I use the Time-Lapse App for exposures up to 30 sec. For longer exposures on Bulb mode I use a wired remote timer. I also have the TriggerTrap dongle on order; supposed to be here by the end of the month.

5) When I'm shooting astrophotography with a camera and lens I use a flash shoe mounted red dot finder for target acquisition.

6) I normally do not use the in-camera Long Exposure or High ISO noise reduction; both OFF.

7) I do, however, like the multi-frame noise reduction for high ISO sessions.

Astrophotography with A7R, New Mexico trip:
https://plus.google.com/photos/116260312230579398213/albums/6001937805993991329

A7S Testing and Playing: (the weather has not been cooperative enough to really stretch the A7S's legs on astrophotography to this point)
https://plus.google.com/photos/116260312230579398213/albums/6032737165630549937

Moon:
https://plus.google.com/photos/116260312230579398213/albums/5526525881847720193/6012627832962655986?pid=6012627832962655986&oid=116260312230579398213

Sky, Sunsets, Star Trails, etc.: (3rd image in album below is A7R star trail).
https://plus.google.com/photos/116260312230579398213/albums/5526561973500317537

I like the A7R for wide-field where its resolution is really handy AND the A7S where its sensitivity is of value. When I can shoot the Andromeda galaxy with 5 sec subs I don't really have to worry too much about whether my polar alignment is dead on, whether my tracking is perfect, whether there is flexure in my configuration or even whether I use an Alt-Az or EQ mount. Last night I shot the Andromeda galaxy off a tripod with reasonable results...

I should mention the A7R is a full spectrum modded camera. The A7S to this point is unmodded but will also have a full spectrum conversion when I get finished fully evaluating it. Full spectrum allows me the use of the camera for regular usage, astrophotography and IR photography; all of course requiring the appropriate filters.

Clear skies!

bwa



Jul 26, 2014 at 01:00 AM
mcbroomf
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p.1 #4 · p.1 #4 · Sony A7r for Star Trails?


David, thanks for the link to dew heaters, I've never been able to do nighttime timelapse because of this...


Jul 26, 2014 at 03:35 AM





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