Antares Rho Ophiuchus wide field.

rcheshire (Rowland) · #1 09-06-2013, 01:31 PM

Tried out the 5DMKII last night to test the cooling. At 5C ambient and dew point not much less I turned the cooling off to avoid fogging the sensor face.

200mm prime lens, 26 lights x 180secs at iso800 with a fixed diaphragm in front of the objective to stop the lens down to about f6.

Unguided, dithered and application of 50 bias frames 10 darks (being really lazy) and 10 flats.

Stacked in PixInsight and post processed in StarTools. A quick rendition and reorientation and re-sampling. I think my laptop memory is partly shot - neither program would accept larger files.

Strictly speaking it needs more data and more processing. But I don't have time. Will work on it here and there.

EDIT: I don't much like using an external restriction to set aperture, except that it avoids Iris spikes. There are some odd artifacts in the image, and terrible vignetting and curvature in the corners. The only usable portion of the image is that within the light circle. No better than the lens wide open at f2.8, despite being stopped down. Perhaps the method is flawed.

Further Edit: uploading another version I seem to have lost the original in the process. As I have modified the image further it no longer exists.

More editing - what a complete c@#k up. Here is the original - reprocessed from scratch.

alocky (Andrew lockwood) · #2 09-06-2013, 03:01 PM

That's a seriously good image. What sort of mount were you using?
cheers,
Andrew.

Larryp (Laurie) · #3 09-06-2013, 03:03 PM

Looks very nice, Rowland

rcheshire (Rowland) · #4 09-06-2013, 03:35 PM

Quote:

Originally Posted by alocky

That's a seriously good image. What sort of mount were you using?
cheers,
Andrew.

Thanks Andrew and Larry.

The mount is an old 1997 Takahashi EM-200B - third or fourth hand. It was designed with unguided or hand eyeball guiding in mind. 5arc seconds peak-to-peak - if you can nail polar alignment. The edges are a bit distorted due to the type of aperture control I'm using - needs improving.

batema (Mark) · #5 09-06-2013, 04:01 PM

Lovely image. Looks fantastic.

CapturingTheNight (Greg) · #6 09-06-2013, 04:09 PM

That's a corker! Certainly does not belong in the Beginners Section.

rcheshire (Rowland) · #7 09-06-2013, 10:05 PM

Thanks batema and Greg.

Still very much a beginner... but it was good to get out last night for a change.

rcheshire (Rowland) · #8 10-06-2013, 06:05 AM

Sorry folks! No sure what happened but the original image disappeared while I was attempting to upload a revised version...?

OK. attached a saturated version of the original.

EDIT: Back in business after reprocessing the original. I prefer working within the data limits of the image and not trying to squeeze every last drop out. I go through stages with processing where I think that's a bit washed out and TRY to make it better. It just needs more data. This one is essentially the same as the other. Crop and remove gradients, calibrate the colour, remove green noise, subtle tweaking with HDR/wavelets to bring out detail, masked saturation to highlight features without raising the background unnecessarily, noise reduction, colour balance and saturation, resample to 50% of the crop.