The Sun - Nov 2nd 2012

[David Smith]

Today's effort. Weather is actually quite bright here today. Won't mention the forecast for tonight

Stack of 62 from 104 @ 1/1600th ISO 100.

[sologuitarist61]

Great image David!

[Steve Ward]

Nicely done. . .

Steve.

[Montana]

Excellent image!

Alexandra

[David Smith]

Thanks all.

Was looking at some of the great images you all put together earlier, and was feeling a little inadequate . So I went back to my original data and processed slightly differently. I used the same stacked data but did things a bit different in GIMP (added colour by using colour balance option and pushed the brightness / contrast adjust sliders as far as I dare).

I think this is better (certainly different), seems to have more punch to it? I would be interested in your thoughts?

Seems like I struggle to get the level of detail that I desire and this could be due to a number of factors:-

- Achromatic optics rather than Apochromatic optics

- Image scale on chip (I did try a barlow but even 1.5x means I cannot fit the whole disk on the chip)

- Processing - I am doing my best in GIMP but it is all a bit of a stab in the dark!

I may need to look critically at my setup going into 2013 and how I can "raise the bar"! Again, any thoughts / suggestions / comments welcomed. I have vaguely considered something like an SW ED80 or WO ZS71 for this purpose but very early days yet.

[sologuitarist61]

Just a couple of points - both Steve and I use achromatic refractors, so don't let that hold you back, and personally, I prefer the first image to the second.

The first has better lighting across the image, whereas, to me, the second is too bright in the centre. I know this happens with solar white light imaging anyway and I am constantly lowering the contrast in my images to try and achieve a 'flatter' image. Look at some of Steve's images and you will see what I mean, they are very even.

[David Smith]

Pushing the contrast to try and pull out detail seems to bring in this central brightening that you have rightly pointed out. What sort of image scale do you get (sample raw image attached)? The focal length of the refractor I am using is 640mm which renders quite a small image on the camera.

Edit: Not the best choice of image as this is one that I did not stack due to cloud but illustrates the point none the less.

[sologuitarist61]

As you will see from the image below I get more than a full image but then I photograph afocally through a Baader Hyperion 13mm EP and not at prime focus (the image has been slightly trimmed on the left and right but not by much.

It is always handy to get the image as big as you can otherwise you are wasting pixels. I then shoot at 16MP and most of those pixels are used to make up the image. Then I take 50 to 100 images (depending on the cloud) which are then stack in Registax5 - unlike most I don't use RAW but large JPEG's (saves time - can you imagine having to wait for 100 RAW files to be processed - nightmare!).

[David Smith]

Thanks Richard, very helpful. I also shoot jpegs for the same reasons! Will try that barlow again when the weather allows. I was conscious of "wasting pixels" as you say.

[DrRobin]

Interesting signature!

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[David Smith]

Interesting signature!

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I was trying to put a dotted line in but came out with gaps in all the time, so I decided to make the best of it and so something different! Should probably update it as Baseball season has ended now. When I tried the other day it moaned that I had more than 5 lines in my sig, so I left it.