M31 with 200mm lens

[Dave Smith]

I didn't get to bed until 5am this morning as it remained clear all night:)

This was taken with a Canon 200mm f2.8 lens (set on f4.5) and consists of 18 x 10mins (3 hr) at iso 800 plus darks and flats. Stacked in DSS and processed in PS CS2.

What a good week this has been!! (3 nights)

Dave

[fatwoul]

Excellent stuff, Dave. I can never get the right mix to preserve the core and also get the dust lanes, but you've done that very nicely indeed.

You lose points, however, for making me jealous about how many clear nights you've had.

[Dave Smith]

You lose points, however, for making me jealous about how many clear nights you've had.

Dave

[dc509]

Very nice image. Can I ask what the advantage is of using the lens set to f4.5 if it can actually go faster? Does it perform better at that ratio in some way?

d

[Dave Smith]

This time it was more by chance than judgement but I remember Olly saying that the sharpness to the edge of the field was improved if slightly shut down.

Dave

[Daniel-K]

wow dave nice image

[Dave Smith]

Thanks for the comments. One thing I would like to know is why the stars have come out pink and how to deal with it. It hasn't happened on my other recent images. Any theories?

Dave

[brantuk]

Smashing shot Dave

[barkis]

A belter of an Image. Isn't it great what can be done with a 200mm lens. Well worth the loss of sleep Dave, and I would get that one off to AN or Starry Night. Nice one .

Ron.

[Dave Smith]

A belter of an Image. Isn't it great what can be done with a 200mm lens. Well worth the loss of sleep Dave, and I would get that one off to AN or Starry Night. Nice one .

Ron.

Not with those pink stars;)

Thanks for the comments.

Dave

[Breakintheclouds]

HOLY MOLY! It was totally worth you getting no sleep for that. Cracking image. The detail in those dust lanes is delightful. Really well done.

[oldfruit]

Excellent results as always Dave, but to be honest you never set an easy standard. Forgive my ignorance but have been away for a while and last i can recall was your compilation of venus phases. Always a pleasure to see you results and am always envious. Thanks for sharing.

[JonH]

Beautiful image Dave, well done.

[MartinB]

Superb work with the 200mm lens Dave

[barkis]

Not with those pink stars;)

Thanks for the comments.

Dave

Must have been the angle of my laptop screen, I didn't see them as pink. Anyway, can you not process the pinkness out of them Dave?

[Coco]

Excellent Dave...

The galaxy looks full to bursting.. plenty of detail, am sure you could work around those stars to reduce the red or is it artistic license to mean a reflection of the artist own eyes..

[kris h]

Excellent image

[jgs001]

Nice one Dave... an excellent result.

clear night... what's a clear night ??

[nightfisher]

top man, that is a really nice M31 very impressive

[swag72]

I really like the Galaxy detail, but those pink stars are a bit too much for me. Can you not create a star mask and then just adjust the red down from there?

[rocketandroll]

Well that pretty much blows my attempt at this with the 200mm L series lens out of the water!! :-) Shows what a difference longer subs make to the detail.

I was about to say how cool it was you'd caught all this little shining pink nebulae in the galaxy which I'd never seen before in Andromeda... but yeah, those are pink stars aren't they? :-)

Looks cool though!!!

Ben

[fatwoul]

This time it was more by chance than judgement but I remember Olly saying that the sharpness to the edge of the field was improved if slightly shut down.

Dave

Indeed, we tell our students that photographic lenses tend to perform their best as they approach half way through their aperture range. So generally a lens with a minimum aperture of f/22 is at its best around f/8, and a lens that can only stop down to f/16 is optically best at about f/5.6.

In part this is because a stopped-down lens isn't using the outermost edges of its glass, where the angles of incidence are their highest and the colour fringing most likely to occur. Instead, all the light being used it passing through the central regions of the lens, at far less exaggerated paths, and is less susceptible to nutty distortions/aberrations.

Of course, that's the rule for daytime use, and astro is far less forgiving. But at the same time part of the advantage of using photo lenses, besides the mammoth fields of view they offer, is the fast focal ratios.

[fwm891]

Great image Dave - some people like 'pink' .

Stopping the lens down helps remove some of the aberrations present at the edge of the fov, certainly with older camera lenses where spherical and chromatic abs were common (B&W days). Stopping down will reduce vignetting (illumination errors) at the corners, but as your shooting flats that should be taken care of.

Some newer lenses have aspheric and/or low dispersion components which allow use at full/wide apertures. Its worth checking the lens specs to see if stopping down is really necessary (other than field illumination).

I would have though the Canon 200 f2.8 has either low dispersion glasses or aspheric elements as older lenses of 200mm f2.8 are rare, with f3.5 or f4 being considered 'fast'.

[badboybubby]

dave, great image, I assume you somehow tracked m31?

cheers, scott

Sent from my HTC Desire using Tapatalk

[Dave Smith]

Thank you all for the replies and helpful tips. Unfortunately my Photoshop skills are rather basic but I am going to attempt some of the advice/tips mentioned here and elsewhere.

I am somewhat puzzled as to why I'm getting those pink stars in the first place as I've not had that problem before. The only change I have made on this occasion is to use 10 minute subs (my maximum was previously 5 mins). Perhaps the stars are overexposed and the simpler way with dealing with this is to repeat the process but with 5 min exposures.

Dave