The weather over the past 3 or 4 weeks in Sydney has been very poor for AP so starting to get a little frustrated ( quite a few nights start out clear for an hour then cloud rolls in until 3am then clear again by 6am , oh well that summer )
Looking back on some images I captured in October/ November I decided to reprocess NGC 2070 Tarantula to see if could squeeze a bit more out the data
Recapping .....
6” f6 Bintel newt on an EQ6-R mount
ZWOASI2600MC OSC camera
ZWO 2” Duoband filter
Bortle 8 skies
3 minute dithered guided subs
No darks
No flats
Stacked in DSS
Reprocessed in Startools V1.6 OSC Linear data set
Composite module using Synthetic composite colour made up of Green and Blue ( Cyan )
Binned image at 71% preset
Gradient wipe and vignette wipe
Heavy crop to 40%
Contrast to 30%
HDR Optimise Heavy
Wavelet Sharpened to 300%
Excluded Deconvolution
Life 2 x Gamma at 35%
Life Less More at 30 %
Colour ( Composite Cyan for Green and Blue )
Noise reduction to 5.5 pixels
Shrink to tone down bright core
Star masks and core mask
Total time for reprocess approx 2.5 hours
Caught the bug Martin.?
Looks good to me but then you are using a big 6 inch...honestly if that does not inspire folk to go for a six inch I don't know what will...I would love to see it's results down South...do you think you have improved on it since your first process?
Alex
Alex
Thanks
I must be the only person using a 6” newt for AP
On the Bintel website it mentions this scope is only suitable for imaging the moon and planets and not suitable for using the larger sensors. I quashed that theory as soon as I started imaging with my DSLR over 3 years ago
Now it’s even more incredible with this beast of a camera , the ZWOASI2600MC
The reprocess did expose more detail from the original post as I didn’t push the Sharpening to hard and didn’t use Deconvolution
Raymo
Thanks
I’m excited every time I go outside and use this new 2600MC camera, it’s a quantum leap from the old 600D
I still use the 600D for lunar and planetary imaging, still does a great job !!
You have some real detail coming out there, the 6" certainly does well. I keep thinking of trying my ASI2600 on the C925 though it would be heavily over sampled and would want binning either at the time of imaging or in processing.
I couldn't find your earlier posts about calibration frames without trawling back a fair way in a search, but I recall you mentioning not using darks with the 2600 (And you have not here) but I found a good reason to use them on the weekend. I set up on Friday night to test the new multi star guiding in PHD2 and grabbed a couple of subs on M45 through high cloud and with the moon rising. The effect I noticed was that if flats were applied and darks are not used, it over corrects the background in the corners as vignetting will have the "real" light levels falling off in the corners but the dark current is quite even over the field, so it gets multiplied in the corners, or anywhere there is a cause of light levels falling off, like dust bunnies.
I have seen the effect before but those times I did not twig as to what was causing it. More or less it says that if you plan to start using flats for calibration you will want to use darks. I would imagine the longer the exposure time of the lights the more noticeable it will be. The attached in order are a single 900 second sub stretched in APP, one with a flat applied and one with a master dark and a flat.
Last edited by The_bluester; 07-12-2020 at 11:56 AM.
Paul
Thanks
The 6” newt is not a popular choice for beginners starting out in AP , they tend to sway towards a small refractor up to 80mm which is fine, but my 6” f6 with its 900mm focal length is a really great versatile scope for both DSO and Planetary imaging
As far as darks and flats are concerned , I’ve compared many images with and without using darks at various exposure lengths and quantity of data with no real difference across the whole image.
I don’t use flats either ( I have taken a series of flats )
Any vignetting in my images are removed by the Wipe module in Startools without sacrificing image quality and uniformity.
I suppose for a lot of people the 80mm frac is the easy way in, short, light, easy to guide and generally nothing to collimate, but the 6" Newt certainly pulls it's weight.
I shoot flats particularly with the 2600 as they are really easy to do with that camera, I may try controlled exposure length flats with dark-flats as well but it works well with auto sky flats in Voyager and a master bias frame so I do them each night now. The ASI294 not producing useful bias frames stopped me from doing sky flats with that camera.
Thanks Craig and Chris
Just need more clear nights now , the weather has been so changeable in the last 3 or 4 weeks along the east coast , I suppose that’s just summer !!
Paul
The 6” newt is not a popular choice for beginners starting out in AP , they tend to sway towards a small refractor up to 80mm
This is me
As I said on another forum, refractors are the best things for beginners. There's so much to learn with this hobby, us newbies don't need to add learning about all the requirements of reflectors to that list, even if they do offer the best bang for buck. For many of us coming from terrestrial photography, refractors are just dumbed-down lenses, so we can pick up the requirements easily.
For me, I've got one refractor (in the sig) and the next OTA will also be another refractor (130 f/7)
After that, I'll jump into reflectors with a RCT but that won't be for a few years.
Anywho on topic, this is a fine image. Feels a little foreboding, which is great. I can almost see Cthulhu himself peeking through.
There are at least two types of astrophotograpers..those who come from photography and those who come from astronomy...an astronomer will rarely be concerned about a Newtonian and know to keep the fl a little slower to avoid tedious adjustment or be aquianted with proceedures and not worried about such adjustment and photographers who just become irrationally afraid of using a Newtonian and believe a small costly refractors side steps the need for adjustment.
For my expeience I found setting up my 80 mm refractors way way more tedious than any Newtonian scopes..you know you do have to get that distance between the sensor and the reducer perfect ..isn't that just a little mucking about?
With a refractors you won't go past six inch app but with a Newtonian that is the app you start with..and you can go to 12 inch relatively cheaply...130 mm refractor costs more than a 12 inch Newtonian...just go f5 if you want simplicity..er isn't that usually the fl of a refractor for photography?
These fears re Newtonians are to a large degree unwarranted.
Think of the money you spend to not have those colours appear in a refractors.. you know those colours that don't appear in even the cheapest smallest Newtonian...when Newton invented his scope it was revolutionary because no colour problems...what did Hubble go for?
Now getting into a RCT...hmmmm I would start with a six inch Newtonian in the first place...perhaps become involved in astronomy before applying the desire to photograph..would not hurt.
Alex
Adam
Thanks for your honest comment about refractors ( I have no issue with refractors , they are the most versatile and popular scopes on the planet ) and you kind comments about my image
I originally started as a visual astronomer with my 6”f6 newt and used my iPhone through an eye piece to image the moon just for fun. It wasn’t until I borrowed my wife’s old Canon 600D , plonked it in the 6” and started taking 20sec and 30 sec images of clusters and nebula that I was hooked and 3 years later I’m imaging with the same scope just about everything in the night sky
Newts are not all the same, I’m sure your aware of that !!
I use the most basic form of newtonian reflector telescope ( 6”f6 and 8”f5 )
I wouldn’t go anywhere near a RASA , RC , SCT or a Mak
You mentioned in the future jumping from a 130 f7 refractor to an RC , now that’s a big learning curve
I’d recommend to start with a 6” f5 or 6” f6 basic newt, easy to collimate , easy to balance, easy to achieve focus , light enough at 6kg and can produce excellent images with the right camera
Thanks again for your comments
Martin
Sorry about this slight hijack, but Martin, I would take issue with your statement that refractors are the most versatile and popular scopes.
I don't see how a refractor of any given size is any more versatile than the
same size Newt, and in large sizes[6" and up] can be very cumbersome, and need a huge tall tripod to avoid lying on the ground to view through it.
Popularity wise, for AP you are probably right, but for visual I'm guessing
Newts are more popular, refractors being limited in aperture.
I can understand not going near RASAs and RCs, but SCTs and Maks?
Some targets require great focal length for which a Newt is next to useless,
unless it is a very large one. Maks are arguably the finest scopes for planetary, lunar, and planetary nebula work, almost never need collimation,
and are compact, so minimal windage issues.
raymo
Sorry about this slight hijack, but Martin, I would take issue with your statement that refractors are the most versatile and popular scopes.
I don't see how a refractor of any given size is any more versatile than the
same size Newt, and in large sizes[6" and up] can be very cumbersome, and need a huge tall tripod to avoid lying on the ground to view through it.
Popularity wise, for AP you are probably right, but for visual I'm guessing
Newts are more popular, refractors being limited in aperture.
I can understand not going near RASAs and RCs, but SCTs and Maks?
Some targets require great focal length for which a Newt is next to useless,
unless it is a very large one. Maks are arguably the finest scopes for planetary, lunar, and planetary nebula work, almost never need collimation,
and are compact, so minimal windage issues.
raymo
Hi Raymo
My statement about refractors being versatile and popular was intended for the beginner astrophotographer. Most folk start out in AP with 60mm to 80mm refractors not 100mm up to 150mm and as these are serious money to splash out not to mention a larger mount for heavier payload etc...
Also my statement wasn’t comparing refractor and newtonian similar aperture sizes ( I didn’t mention “ at any given size “ )
Next time I’ll be more specific !!
Thanks for your comments , always on the ball
Final, and again apologised for hijack.
Martin, I've heard it said that blokes in my age group can be dogmatic, pedantic, argumentative, or grumpy, but this
is ridiculous, I seem to be all four.
raymo
Raymo
You keep us all honest ,no apology needed
Since you WA astrophotographers are not getting hammered week by week by low pressure systems and troughs ( ie inclement cloudy weather ) here on the east coast we expect to see more Astro images from out of the west !!! 🔭💫🌟🌙
Martin
