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chiralchemist

First shot at M42...it's been years in the making

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Well, 3 years after first getting the astrophotography bug, I managed to get my first reasonable image of a deep sky object, M42.

M42 16th January 2015

Previously, I've been limited to widefield shots using a 105mm f2.8 Sigma lens, but I've always wanted to get a short-tube for 'closer' shots but have been limited by cost. I managed to get a 400mm ST Astrotech 66ED on Astronomy Buy and Sell just before Christmas, and armed with an excellent second-hand EQ5, my Canon 1100D, and a Dew-Not heater, the above is the result. I took the usual flats and darks, used Deep Sky-Stacker to process and Gimp to tidy up the image. The result is from 20 shots of 30 seconds each.

Problems to resolve for the next session.

  • Polar alignment - could not find stars on the East and West horizon. I used the polarscope but I think that the slower scope (compared to my zoom lens anyway) probably need more precise alignment.
  • Aligning the scope - need to get a decent finderscope attached as I was 'flying blind'. Telrad gets good reviews?
  • Horrific field curvature - I did buy and try a Williams Optics Type IV but there was not enough inward travel, so returned it. I also have a Meade SCT flattener that I thought might work and screws onto the SCT at the back of the scope. But again, not enough inward travel to get focus. Anyone know of a way to get around this? I found this article but it looks like they use a W/O type II - not widely available.
  • Longer term - autoguiding - I guess this would resolve (to some extent) precise polar alignment issues. I have a 9 x 50 finderscope I think I can use, and also a fairly cheap f5.0 short tube. I've a couple of web-cams but the QHY5 seems to get the best reviews? Any thoughts.

So overall, riding a high this weekend, even though I now have to wait for the weather before my next attempt.

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Hope to be following in your shoes soon, as bought decent scope, mount and camera yesterday - see if I can get a shot in under 3 years

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Well done on your first DSO, lots of nice colour and nebulosity in there.

You now have the wonderous adventure that is: how do I get the data out. I am sure I spend twice as long processing my images as I do taking them in the first place.

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Well done on your first DSO, lots of nice colour and nebulosity in there.

You now have the wonderous adventure that is: how do I get the data out. I am sure I spend twice as long processing my images as I do taking them in the first place.

Hasty processing.... :rolleyes: Only twice?

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I think the FF/FR in the article is a WO mk ii not mk iv. The cheapest way of correcting the field curvature is probably using the SW field flattener which has no reduction factor but is optimised for F5.5~F6 scopes and does not break the bank as it is only about £70.00.

You need to find a way of obtaining good focus as your stars are soft, either using a Bahtinov Mask or using FWHM software focusing. Good first try BTW.

A.G

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I think the FF/FR in the article is a WO mk ii not mk iv. The cheapest way of correcting the field curvature is probably using the SW field flattener which has no reduction factor but is optimised for F5.5~F6 scopes and does not break the bank as it is only about £70.00.

You need to find a way of obtaining good focus as your stars are soft, either using a Bahtinov Mask or using FWHM software focusing. Good first try BTW.

A.G

Thanks for this suggestion about the SW flattener - I'll check this out. I did use the FWHM feature in APT, and I'm not sure that the soft-stars are a function of me not getting this quite right and / or not having my polar alignment spot-on. A mask is definitely on the shopping list!

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+1 for the Sky Watcher FF, I use one and it works pretty well.

What connections are on the Skywatcher FF? My scope has a SCT tread on the tube, but I do have a Baader 2 inch "push"-adaptor.

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Sorry for the late reply, the SW FF is a 2" push fit on one end and t-adapter thread on the other. It goes straight into my focuser tube. Which scope are you referring to? Does the Astrotech have an SCT thread on it then?

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Sorry for the late reply, the SW FF is a 2" push fit on one end and t-adapter thread on the other. It goes straight into my focuser tube. Which scope are you referring to? Does the Astrotech have an SCT thread on it then?

Roy, thanks for that. The Astrotech is apparently like an old Williams Optics 66, so has SCT threads on the tube. However, I have a Baader adapter that screws on to let me push fit 2 inch accessories. Inward travel might be the issue again - but I'll see if it will work. Simon

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