Star Fields! With M8 (two samples)

K

krimple

Guest
Ok, here we go--a fun torture test with the M8. We had very clear skies in Eastern PA last night, and for grins, I shot these star fields with the M8. Shot with a wide open Ultron at f/1.9. I didn't bring my shutter release, but steadied the camera on a tripod (cheap velbon) and carefully pressed and released the shutter on Bulb. Noise reduction was enabled (can it even be turned off?) Lens focused to infinity.

I had to do some cleanup, these are worked over in Lightroom. On the first one, you can see the Andromeda galaxy almost 1/2 of the way down in the right hand half of the image. The Pleiades are at the bottom mid-right of the second image.

Before the samples below, here are my flicker links for both images if you're interested in scanning deeper:

http://www.flickr.com/photos/krimple/306857131/

and

http://www.flickr.com/photos/krimple/306856913/

(those are resized to 2048 long).

I'm surprised at the level of detail, and am interested in what I can do with more time. The noise got untolerable after about 15 seconds, so I figure there is an IR heat source somewhere in the camera itself (power supply?) but that's not unusual. I'm sure the EOS 5D would be a better match for this work.


ISO 160, about eight seconds or so
306857131_afa235c8df_b.jpg


ISO 640, about 15 seconds or so
306856913_52517cb117_b.jpg


Ken
 
Those are very funny posts. I think any planet or star with a magenta cast should be eliminated. I propose a star trek planet killer for just that purpose. Maybe Leica can launch one with a robot pilot and we can get free rides.

BTW I figured the heat noise would be there. Just making a note of it. I've seen some phenominal EOS 20D star images, but I'm not sure what the people did to get those.

Ken
 
That's a good lens! Round star images at the corners with a fast lens, wide open, are uncommon.
The Andromeda Galaxy is pretty obvious in the first shot. Does the camera have a dark frame subtraction feature?
 
I think it is bad pixels!! Everone knows the good ones are mined in south Austrailia. Occasionally Leica gets a batch mined in Siberia. They are only good for photographing walruses and commissars!!!

Tom
 
Bryce said:
That's a good lens! Round star images at the corners with a fast lens, wide open, are uncommon.
The Andromeda Galaxy is pretty obvious in the first shot. Does the camera have a dark frame subtraction feature?
Click to expand...
It does. And I wonder it did not kick in here.
 
Every time the camera took a shot longer than 2 seconds it kicked in. The noise was there, though I'm sure the camera wasn't meant to be that sensitive. I'm doing more experimenting at some point in the future (next time I have time on my hands and dark skies).

Ken
 
You can't turn NR off? I thought the M8 applied very little NR on its images?

The first one showing the galaxy is impressive! I didn't think that could be acheived at ground level..
 
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The good looking photos taken with the 20D are most of the time done with a removed or downgraded IR filter in front of the sensor and an amateur telescope. They actually pay to have it with higher IR sensitivity. So money saved with the M8. ;) scnr
btw: I like the first one.
 
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ywenz said:
You can't turn NR off? I thought the M8 applied very little NR on its images?

The first one showing the galaxy is impressive! I didn't think that could be acheived at ground level..
Click to expand...

Two different kinds of NR. There is high-ISO noise reduction (which the M8 may do in jpegs, and may be adjustable (I don't recall at the moment)). That's the kind that the Digilux 2 suffered from at 400 - smearing of the image to blend the speckles together.

Long-exposure NR does something different. For exposures longer than about 1 second, the camera makes the "real" exposure with the shutter, and then reads the chip's signal again with the shutter closed, for the same amount of time. There should be no signal from the chip when the shutter is closed, so if any pixels do show up, they are spurious hot pixels that have nothing to do with the light in the scene, and the camera then finds and deletes those specks in the real picture.

No smearing, however.

Long-exposure NR is kind of like Digital ICE in a scanner. Where the scanner scans once for the image, and once (in infrared) for the dust alone, and then subtracts the dust from the image - the camera exposes for the scene, and then exposes for the noise (with the shutter closed), and subtracts the noise.
 
You may be aware that those of us who do a great deal of astrophotography have specialized cameras that eliminate IR blocking. Scientific cameras have none, and some of us have bought Canon Rebels modified with the IR filter taken off the sensor. The reason is that much of the light in the heavens is IR and the normal IR filter blocks it. The pictures that we get, whether using a modified Canon or a scientific camera magnificent. So that begs the question, will the Leica pick up astronomical objects other cameras will not. The answer is probably yes, although not much. If I look at my modified Canon shots during the day vs. the M8 there is a vast difference. But there you are. You have found a use for the IR problem on the M8. If you want to see what some astronomical pictures without an IR filter, look like, go to http://www.sciencecenter.net/hutech/gallery/html/h595612.htm. This was taken with a Canon Rebel with IR filter removed.
 
I've done a few little tests over the years but never got enough resolving power on a non-clock-drive shot from a digital that captured a galaxy. So, when I zoomed in and saw even that level of resolution I got interested.

I have an old tripod falling apart with a clock drive on it--I might pull the base and put together a platform to do some more extensive shooting. I'm not sure the M8 can give me a quiet enough internal platform for longer shots, but it's interesting anyway.
 
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