Astronomy, Photography and Weather

General Category => Astronomy & Space => Topic started by: Big Dipper on March 13, 2010, 02:23:28 pm

Title: A couple of shots from last weekend
Post by: Big Dipper on March 13, 2010, 02:23:28 pm
Last weekend I was fortunate enough to be given three clear nights in a row to indulge in this nutty hobby of ours. Furthermore, with its southerly declination at the time, the Moon was not going to be a problem either.

For a change, I used my 500mm cheap f8 telephoto lens + Orion LPR with my modded 350D. As usual, the set up was mounted on my AstroTrac. I often find that, even with the filter, a lot of my shots nevertheless look pretty washed out - sometimes after even only a five minute exposure. I therefore limited to the exposure to 180 secs each - all NINETY or so of them (plus darks & flats of course). When the AstroTrac had reached the end of the screw thingy & had to be rewound again, I managed to reframe the Rosette again identically to how it was previously (having modified an erect image, right angled 6X30 finder in the hotshoe adapter on my camera has been an absolute godsend). Afterwards I was very glad to see that Deep Sky Stacker didn't have any problems with combining the stacks. Watching all of the frames download from the camera it was great to see that the position of the nebula remained unchanged over each two hour session - testimony to the AT's tracking ability & ease of polar alignment.  :)

Despite the slow f ratio & short exposures, I still managed to capture a good deal of nebulosity - though try as I did, I was disappointed at the lack of colour in the stars despite trying Noels astro tools on the images. Still going by my usual standards I was pleased how this turned out.

Taken on the previous night, this was my first ever attempt at getting the lovely globular M3 in Canes Venatici. It's a composite of 44X150 sec each light frames through the same cheap 500mm f8 lens, fitted with an IDAS LPR with 12 darks & flats as well. Tracked again with my AT and stacked in DSS with further processing in PS & ImagePlus (I used the Digital Development function here).

Title: Re: A couple of shots from last weekend
Post by: martinastro on March 13, 2010, 02:43:24 pm
All I can say!. Great write up and spectacular images Andy, I really like M3, one of my favourite globs, the resolution of those resloved stars is incredible.

Title: Re: A couple of shots from last weekend
Post by: Paul on March 13, 2010, 02:51:41 pm
Those are great shots Andy, love the Rosette. You also seem to have mastered the art of getting the focus bang on which is always a chore. M3 is crisp and beautiful - can't put my finger on why it is, but I always prefer the look of this globular to M13.

Title: Re: A couple of shots from last weekend
Post by: brianb on March 13, 2010, 02:57:12 pm
 :o Terrific shots! Shows that in the right hands a cheap lens can give a Tak Epsilon a run for its money!  ;D

Title: Re: A couple of shots from last weekend
Post by: rjgjr on March 13, 2010, 03:39:16 pm
Fantastic shots Andy. The dedication to the hobby really shows in you're work.

Title: Re: A couple of shots from last weekend
Post by: Big Dipper on March 13, 2010, 11:42:31 pm
Many thanks for the kind comments everyone.  :)

Paul I had to smile at your comment about 'mastering' the focus. Truth is that I have the lens taped down (and also marked with a metallic pen on the lens barrel) at where I determined the point of focus was & just use that setting on each imaging run (that kinda makes me seem like a bit of a slob, methinks)!

On the question of globulars I think that because M13 is widely regarded as the 'showpiece' glob for us northerners, seeing/imaging some of the lesser known ones such as M3 & M92 becomes far more appealing to some of us. There is one cluster (an open one this time as opposed to a globular) which I would love to get this season before it disappears into the evening twilight. That is M41 - a bit of a challenge for us in the UK due to its southerly declination.

Brian, I bought this lens, second hand, in 1986 when I was heavily into daytime SLR photography. In fact the case which I subsequently bought to house it in was more expensive that the lens itself! Up to now I've only used it on odd occasions for astro imaging, partly because its fastest speed is only f/8. I was very pleasantly surprised at the sharpness of these images which has made me look at this lens in a new light! Another thing that I like about it is that the barrel unscrews which allows me to fit one of my 52mm light pollution filters in place with a couple of pieces of masking tape!