Tiny Small

Cheers Olly. I have to say, getting the right balance is a bit trickier than with LRGB. More rewarding though.

12 minutes ago, jjosefsen said:

Yeah you are right actually, my bad.. But is the Halo more significant in one particular band i wonder?

I replied when I was half asleep last night, so I apologise for missing this bit out: the individual channels look fine, but the Ha has physically bigger stars and i think that, combined with aggressive stretching is what is causing the halos. I think it's a sub length and processing  issue. I'll need to take a look at some individual subs.

4 hours ago, jjosefsen said:

Aaah.. I think those are on the "budget'y side" and could very well be the source of those halo's, actually they might be the same as gen. 1 ZWO filters.. (Not sure though..)

My guess is it would be particularly bad in the OIII master??

I just purchased a set og Baader LRGB filters + Ha + OIII and i researched it quite extensively, and alot of the cheaper filters have problems with halo's particularly in the OIII filters.

They're about the same price as the standard baader ones (£250 for three 1.25 inch filters Vs £270 for the baaders) and the o3 and S2 have a narrower range than the baader filters. 

9 minutes ago, jjosefsen said:

Lovely details in that image. Can I ask what filters you were using, make and band width?

Thanks. I'm using Altair Astro filters. 7Nm Ha, 6.5 Nm OIII and SII.

Had a play with using a desaturation layer and some extra curves. Think it has improved it a bit.

1 hour ago, MartinB said:

Great first hubble palate NB.  With regard to halos there are any number of methods or removing and you probably need to know a few to deal with different situations.  One curde but very effective way in PS is to apply a blur in photoshop using filter/ dust and scratches to your stretched colour layer.  Don't over do this since you loose colour intensity and don't try to eliminate all the stars.  Layer the blurred colour image onto your luminence using colour as the blend mode.  Then be brutal!  use the clone stamp or healing brush (for smaller stars) over the offending stars and halos.  Most of the time this will work nicely but it can be a bit labour intensive.  

One thing to watch out for when using big blurs is that colour can be stripped from fine filaments.  You can get around this by layering an unblurred colour image over your blurred one and then just revealing the colour filaments using a layer mask.  This is all very un pixinsight and will horrify processing purists!

When I used to shoot fashion and beauty, the skin was edited by non-destructive dodging and burning at pixel level, with a person's face taking a day or two sometimes, so the method you suggest isn't that labour intensive. I think I'll stay away from blurs as it's very easy to mess it up and very hard to get it right, but if there aren't any decent ways of globally controlling the halos then next time, the clone tool around individual stars might be a sensible option or perhaps just painting them out on a colour layer.

One thing that I didn't realise was that a luminance layer can be used with narrowband. Seems obvious when you say it but it just didn't cross my mind. I'm assuming it's usually a Ha layer?

2 minutes ago, Adreneline said:

Hi,

Very nice image - I really like it.

You don't mention which processing software you used. I use PS to create Hubble Palette images (Annie's Astro Actions) and run into problems with magenta halos, however, I discovered there is a nice fix for it in PI using a PixelMath script (attached) I found on the PI forum. Apparently the same thing can be achieved using ColorMask under the Script menu but as yet I've not tried that method.

HTH

Adrian

 

remove magenta stars.xpsm

I stack in either DSS or Astroart (depends if Astroart gives me issues or not), then do the entirety of my processing in PS. I don't use actions though as, coming from a conventional photography background, I'm well versed in editing the conventional way.

So this is my first attempt at a three colour narrowband image and I ran into a few problems controlling halos around some of the stars. Quite sure that I'll figure it out in time but any advice would be welcome, as would advice on processing in the Hubble palette.

Shot with the ZWO 178 mm-cool and Altair Astro 60 EDF at 200 gain and 65 offset.

Integration:

Ha; 72 x 300s 

OIII; 59 x 300s

SII; 27 x 600s

Total integration time just under 15.5 hours.

Whilst a concreted in pier and observatory are the ideal way to go, you would be surprised with what you can achieve just using simple and none-permanent solutions. I have my scopes mounted on an NEQ 6 pier that stands on some flat paving slabs dug into the grass. Polar alignment needs adjusting once a year or so and I have no issues with tracking and guiding. The scopes stay outside all year and are covered by a plastic garden storage container on wheels. This has a slot cut in the bottom and gets wheeled on and off when I want to use the scopes. I can go from everything being put away to my first slew in about 90 seconds. To combat moisture in the little hut, I have two large desiccant tubs that get swapped a couple of times a year, and the scopes are covered in the hut by a bed sheet and a small tarp that are just thrown over them. This stops dew forming on the equipment. Certainly not hi-tech or ideal, but it works.

M81 from the other night in Didcot. I'm enjoying using the 130 when I have time but I'm still struggling to get th autofocus working right. Might need to invest in a wider field of view camera too. 0.85 arc sec/pixel is really pushing it sometimes.

A very informative review. I was debating whether or not to give this a go for when it's cloudy here. I eventually decided not to due to the expense of long imaging runs but I know a few people who use it and love it.

It's good to hear that the support structure is there too.

10 minutes ago, carastro said:

Got myself a coma corrector, Spacing sorted, collimated - First test shot:

Fingers crossed this is going in the right direction, shame it's full Moon as it's a clear night tonight, eager to try a first image with it.

TEST SHOT, M45 Next to a full Moon, but just to check collimation and stars:

(Not sure what that hazy bit is top right of image), any thoughts?  Had to do a gradient exterminator on this as you can imagine, but the hazy bit was noticeable when doing the subs, which are a batch of 5mins luminance.

Carole 

Collimation looks good. How many subs did you take and is that fuzzy bit exactly the same on all the subs? Could be a cloud. 

The clouds rolled in and stopped imaging again but I got a couple of hours Ha on the Crescent. 34 x 300s with a few darks applied. It needs MUCH more data before I move on to O3 and S2, but here it is, a work in progress:

19 hours ago, mftoet said:

 

One of the many refractors + correctors, extenders and reducers of Borg / Astro Hutech might be the answer. I once owned a Borg 101ED that covered Medium Format. I used it with a Mamiya 645 camera. 

http://www.sciencecenter.net/hutech/borg/astrogr/index.htm

You can also keep an eye out for secondhand Pentax refractors from the analogue age. Remember that "full frame" (35mm) coverage was the standard back then. 

Interesting... I've got a 645 and an RZ 67 with a phase one digital back collecting dust at the moment... wonder what the wife will say when I pitch that idea to her.

I've now swapped out the focuser on my 130 with a rack and pinion focuser from a 12" OO imaging Newtonian. This has a different size drawtube with an odd converter on the top to take it back down to 2". The focuser fits better than I expected and the gaps have been filled with silicone sealant. To achieve focus, I had to take 10mm off the top of the focuser and move the mirror about another 10mm up the tube. I've conducted some initial focus tests and it achieves focus fine. The robofocus also seems much happier with the R&P and over a few clear nights, I'll see if it makes a difference with autofocus routines. I don't know what this is going to mean for light loss with the mirror being so far up, but I'll see over the coming weeks.

Has anyone successfully swapped out the focuser on a 130 PDS for a rack and pinion? I'm in the middle of trying to convert the Crayford but it's not a simple operation. Fitting the rack and pinion is easy but as the Crayford is a pressure drive and the rack and pinion is a geared drive, I'm running into issues with stability and spacing. Though the spacing is relatively easy to sort.

So, if anyone has done this, any advice? Or has anyone successfully swapped an entire focuser? What issues are there? I'm assuming that light leakage is an issue though that shouldn't be too hard to rectify. The differing radii are on obvious issue but in terms of actually securing and squaring it, that shouldn't be anything a few washers can't sort out. Other than that, can anyone foresee any major problems?

1 hour ago, Uranium235 said:

Or alternatively, you could not let it bother you

 

I did that for a long time. It finally got to me the other week though so I ended up doing both. I also finally got it collimated last night with the aide of a Cheshire. Took the primary out to clean and give it a new centre spot, took the secondary out to clean and just started from scratch. It's a good job I did too as everything was miles out. The only bit I had trouble with was keeping the secondary looking round whilst aligning it to the primary. In the end , and after about 4 iterations, I settled for 'pretty round' though not perfect. Also, keeping the primary screws equidistant from the edge of the field of view resulted in the centre spot being a couple of mm off so I moved the spot to the centre and although the screws aren't equidistant anymore, they are all still visible so it should hopefully be okay. I'm just awaiting a star test now.

23 minutes ago, Thalestris24 said:

Um, you'll still need a hex key to remove the current bolts! a 1.5mm key seems to fit mine.

Louise

Yes they need to come out. And they can be in very tight. Get the longest shaft 1.5mm key you can. Halfrauds do them at reasonable prices... or, if you aren't risk averse, your normal key with a set of pliers on the end for added leverage. Giving them a tiny nudge clockwise can often break any bonds that have formed, allowing you to then unscrew them anticlockwise. If you do that though, it needs to be a tiny nudge, barely enough to move it at all.

2 minutes ago, Stub Mandrel said:

Definitely fussier to set than the 150PL - you would think a longer scope would be harder!

Yup. I've just lopped 15mm off my focuser AND moved the mirror up by about 10mm. Focus has moved from almost fully in to about 3/4 out which solves the problem of protrusion into the light cone, however, it's not somewhat more difficult to collimate. To the point where I'm tempted to go to the dark side and buy a frac. But I won't. I'll persist as I always do. Got a new Cheshire on the way as the laser just isn't cutting the mustard anymore.

M33 with 6 hours of data at 0.85"/p. I've taken 15mm off my focuser but it's still protruding into the light cone. Pretty sure my collimation isn't great either. This image is also posted in the deep sky sub forum.

I go down to headley and box hill a fair bit for observing. If you ever want to tag along, I have plenty of room in the car  

Going to be following this with interest.

I also just stumbled across this thread. Excellent idea that mini obsy.

Where abouts in Kingston are you? I'm down Kings Road, not far from Kingston Gate to the park.