The Wishing Well Cluster (NGC 3532)

[dugnsuz]

Hello all...

First light from my new lens - Canon 300mm f4L IS.
http://www.photozone.de/canon-eos/172-canon-ef-300mm-f4-usm-l-is-test-report--review

Stuck the 1.4x Extender on to push the FL to 420mm - wanted to see how the lens would perform with all that glass between the camera and the stars!

I'm pretty happy with the results - very sharp and flat field.
Love the daytime results too. I've posted a pic of a "star" from my son's Under 11's soccer match yesterday to illustrate.

Captured an excessive amount of exposures for the subject - fell asleep during the session and ended up with 35x300sec subs (2.9Hrs worth!!)

Thumbnail looks very red - but processing was minimal...Levels, Curves and mild sharpening only. Perhaps that part of the sky in Centaurus is particularly busy!?:shrug:

Details...
21.5.09
Canon 40D (modded)
Canon 300mm f4L IS + Canon 1.4x Extender (420mm FL)
HEQ5 Pro Mount
Autoguided with PHD
35x300secs, f8, iso1600.

Processing...
Images Plus, Photoshop CS4.

High Res...
http://s327.photobucket.com/albums/k461/doug-robertson/?action=view&current=9c.jpg

Cheers
Doug:thumbsup:

[Tilt]

Nice image Doug, I didn't know you were in the market for a 300 f/4L (nice glass btw). How were you when you woke up from your nap? 'Oh dear!! Has the object gone behind a tree? Is it raining!?' :lol:

Michael

[Hagar]

Certainly looks like a nice lens Doug. You must be getting quite a collection by now.
The image is nice and cleam and shows just what an L series is capable of in the right hands.

Nice one.

[dpastern]

Looking good Doug!

The 300mm f4 IS is a nice lens, although my copy has AF issues (and has had since day 1, I just never really used it enough earlier on to realise).

Dave

[dugnsuz]

I thought mine did too initially - seemed objects at infinity weren't as sharp as the reviews would have suggested. I had read about QC issues and variability in different copies of the lens and thought I might have a dud!!

Did a bit of googling and ended up just using the centre AF point only for autofocusing - this cured the AF problem (although it is a bit slower than my 70-200mm f4L zoom).
Seems the 9 point AF mode was locking on objects closer than the infinite object I was 'focusing' on!:doh:

Thanks for the comment on the pic too!
Doug

[dugnsuz]

Michael, Doug - Thanks.
My collection runs to 3 lenses!! But that's cool for me - I can image from 50-420mm through very nice glass...so I'm happy:).
Michael - luckily when I woke up the cluster was still in the FOV under a clear sky!!:zzz2:

Doug:thumbsup:

[jase]

Looks like its a keeper Doug. Nice image of this open cluster. In the larger resolution there appears to be subtle star elongation in the lower left of the frame. Is the camera square with the optical plane?

[dugnsuz]

I see what you mean Jase - looks slightly out of focus with respect to the rest of the frame.

How does one go about remedying this if the DSLR isn't 'square'?

The night this image was taken was quite breezy - I wonder if this effect may be caused by a shaky sub in the stack...but why would that effect just one corner!!??:shrug:

Any ideas?
Doug:thumbsup:

[avandonk]

Looks very good to me Doug. You will find that the the micron size of your detector will show the slightest fault in the image train. A zoom lens by having a moveable bit in the middle will never be 'square'. It is the old story of compromise. Do you have versatilty or self imposed 'perfection' with no room to move. You choose!

I have a 300mm lens that costs 7K+ new and it is still shown to be wanting!

Just keep taking images. At least you have something in your hot little hands. The naysayers have nothing. This of course excludes Jase as his advice is well worth listening to.

Bert

[dugnsuz]

Cheers Bert - just went back and re-examined a few of the subs from this stack...seems to be a slight difference in focus from the centre and edge stars as would be expected - perfection in lenses is like the 'zero' some mathematical equations can never seem to reach!
This star elongation in the lower left of the stacked/final image doesn't seem to be pronounced or evident on each sub, so I hope that it may have been introduced by my processing/stacking.
Cheers
Doug:thumbsup:

[Paul Haese]

Lovely image Doug, looks to be an interesting target. I like the faint tendrils of gas in the image too.

[dugnsuz]

Thanks Paul - wish I had 'blasted' it at 600secs, f4, iso1600 to bring more of that faint nebulosity out, but this was really a test of lens sharpness.
I've never really been an imager of clusters(!), but this FL seems to suit those lovely open varieties.
Cheers
Doug:thumbsup:

[Craig_L]

Good one Doug. What program did you stack it in? Maybe you could also try it without the extender.

[dugnsuz]

Thanks Craig,
Stacked in ImagesPlus.
The extender was used to see if I could push it!
"First light" is a bit of a white lie - I managed a single 105sec sub at f4, iso1600 the night before. Clouds stopped play!
Very noisy, and hazy due to those clouds!

[Craig_L]

Hard to tell on that size image but it doesn't look like the stars are elongated at lower left on this one.

[dugnsuz]

Hope not!!
Lens shows promise even in the hands of this idiot!!
Will post more soon, weather gods willing...
Would be nice to give my Ha filter a run with this lens too.
Cheers
Doug:thumbsup:

[Tamtarn]

You have a great selection of lenses now Doug and producing excellent results.

The cluster has come up a treat :thumbsup:

[jase]

I'd still say its a winner Doug. It maybe the data registration process is the cause as you suggest. The Ha filter is going to give you tighter star profiles so it will be interesting to verify the result and compare with your previous images. It maybe the extender or coupling...may need to get crafty a shim it to get it square. Though I've never heard of anyone doing this before. I'm assuming it doesn't occur with the lens alone i.e. no extender.

[Alchemy]

just had a look at the large pic on your website, quite a collection you have there.:thumbsup:

[dugnsuz]

Thanks B&D - just need one more lens, honest...then I'll be truly happy!!:whistle:



Agreed jase, it's a cracking lens - weather has stopped me from testing further. Expect more soon!



Cheers Clive - the good, bad and ugly are all there!!:lol:

Cheers All
Doug:thumbsup: