There was a slight break in the weather yesterday, long enough to drive out to York and get set up alongside Barry and his 28". Although it looked promising initially, clouds kept forming above and there were very few patches long enough to get a decent image.
Despite this, I was determined to see what the Zeiss Sonnar 135mm APO could do on the D810A. This is a stack of 39 of the least cloud affected 1 minute exposures at f2.0. And as far as I can tell this lens has no faults at all.
A higher res version is here: http://www.astrobin.com/full/235968/0/
processing includes calibration, stacking and a quick levels stretch followed by a curves transformation in PI.
I can't remember the last time I got a cloud, haze or smoke-free night here, but of course my problems are trivial compared to the folks in the SW of the state who are really doing it tough right now.
cheers,
Andrew.
This is so far removed from what Trish and I normally try to do that I don't usually comment, but it caught my eye.
There seems to be a super-faint outer spiral arm passing anti-clockwise through the point exactly half way toward 9 o'clock, and still in vaguest evidence exactly half way toward the bottom left corner.
Beautiful shot. I'm going to have a crack at this as soon as the clouds nick off.
Mark
Thanks Mark!
Quote:
Originally Posted by Placidus
This is so far removed from what Trish and I normally try to do that I don't usually comment, but it caught my eye.
There seems to be a super-faint outer spiral arm passing anti-clockwise through the point exactly half way toward 9 o'clock, and still in vaguest evidence exactly half way toward the bottom left corner.
Like the subtle use of colour.
Best,
Mike
Thanks Mike, I saw it too, and am trying to figure out if it's an artefact of pixinsight's DBE tool. It survived a few different iterations, so it may be a robust feature, and it doesn't seem to coincide with any of the control points. Many of the subs I used have some cloud in them, so I've been fairly harsh with the rejection criteria, but, I think I can see it in one of the subs that was good. If I ever get a night free of haze or cloud I'll know for sure, and at f2 that lens sucks a lot of light, so it is just possible it dredged something subtle up in 40 minutes!
Cheers,
Andrew.
Great shot, Andrew ..
Big stars are perfectly fine in the centre, but further outside they look “split-in-half”; I have the same effect with 60Da and a couple of low-F Canon lenses ..
Great shot, Andrew ..
Big stars are perfectly fine in the centre, but further outside they look “split-in-half”; I have the same effect with 60Da and a couple of low-F Canon lenses ..
Hi Ian- I notice the bands that split the stars are more or less concentric. I also saw the same effect with the Nikon 300 PF f4 lens I tried recently. both nights were hazy - although I don't know why there would be an interference effect.
Great shot Andrew. Im out at the observatory and only viewing on my samsung galaxy but looks to be a fine lens!
I will have a better look on the puter moniter when i get home
Mike
Thanks Mike - I certainly appreciate your constructive comments! I'm not entirely convinced the 'spiral arm' is real though, as there's a even fainter, concentric thing visible further out at extreme stretches and I've no idea if it's background cloud or not. I will definitely have another go at this image when there are properly clear skies to check.
Quote:
Originally Posted by raymo
Lovely image, can I ask what ISO you used?
raymo
Thanks! ISO was 1600. It was about 20 degreesC ambient.
Quote:
Originally Posted by RB
Beautiful image Andrew!
RB
Thanks Andrew
Quote:
Originally Posted by RickS
Great result, Andrew!
Cheers,
Rick.
Cheers Rick! It's a very minimal PI workflow, but if I ever get a good night's imaging on this I think there's a lot more in that data.
Thanks Russel! I resisted the temptation to hit that saturation slider this time, as I felt it was disrespectful to the colour
Thanks for linking to that other post - the arm coincides nicely with the extended features in that magnificent shot.
Cheers,
Andrew.
Ok, home now and looking at it on a good monitor...and it still looks good
As for the extra arms and patches I think most of them are real but hard to find them all appearing consistently in other wide field shots
With the limited understanding I have of PI DBE I am concerned that it might sometimes manufacture as much as it reveals when it comes to the really faint stuff..?
But a great shot regardless
Mike
edit: Ah, oops, ok you didn't mention DBE..? Where did I get that from then..? Going a bit senile...
Ok, home now and looking at it on a good monitor...and it still looks good
As for the extra arms and patches I think most of them are real but hard to find them all appearing consistently in other wide field shots
With the limited understanding I have of PI DBE I am concerned that it might sometimes manufacture as much as it reveals when it comes to the really faint stuff..?
But a great shot regardless
Mike
edit: Ah, oops, ok you didn't mention DBE..? Where did I get that from then..? Going a bit senile...
Not at all - I mentioned it in my reply to the other Mike! You can set the order of polynomial it fits the background gradient, and you can also see what it is subtracting, and in this case the only potential source is a random few bits of cloud lining up in the subs.
It certainly matches the features imaged by Troy in the link Russel posted, so I'm claiming a rediscovery
Cheers,
Andrew
Not at all - I mentioned it in my reply to the other Mike!
Ah yes ..I knew I had read it, senile, see?
Quote:
You can set the order of polynomial it fits the background gradient, and you can also see what it is subtracting, and in this case the only potential source is a random few bits of cloud lining up in the subs.
It certainly matches the features imaged by Troy in the link Russel posted, so I'm claiming a rediscovery
Cheers,
Andrew
Nicely done Andrew! I think you may have clipped some data though (I think anyway). The lens vignettes heavily at f2.0. At f2.5 with tracking (Astrotrac), this lens is awesome! Run some flats and you may pick up some extraordinary stuff around periphery of this field.
The Zeiss 135 on a D810A - what a weapon! You are going to have fun with that setup. I am running the same lens on my full spectrum 6D with some very satisfying results.
Yes, there is some spiral action going on with the LMC. It showed up with my all sky imaging project that I completed some time ago using the full spectrum 6D + siggy 35mm f1.4. I could hardly believe the extent, and that no one has recently picked it up. I have never posted the result of the all sky, but might just do so.
Although Orion has been quite a distraction, I am having a good go again with the Zeiss 135. I am hoping to reveal this section of sky in far greater detail. Cheering for clear skies in SE QLD - something that is quite rare this time of year.
..I knew I had read it, senile, see?
