The EQ3 DSO Challenge

[Stub Mandrel]

8 minutes ago, bobro said:

Hope EQ2 imagers can post here too !

Excellent stuff! The myth you can't image with light kit is surely debunked?

[bobro]

On 03/11/2016 at 08:50, Stub Mandrel said:

HELLO ALL!

If you image using a 130P-DS on a lighter mount, such as an EQ3, you probably use subs of 30 seconds to a couple of minutes.

The Alt-Az imagers have recognised the need for some more topics to provide places to discuss the equipment and techniques opened up by more sensitive, lower-noise modern cameras.

We also need more showcase threads, like this, so that instead of telling beginners not to bother trying imaging unless they have masses of expensive kit, they can see the possibilities of imaging on light and alt-az mounts.

If you have a view on this, please share it here:

 

 

I was put off trying astrophotography a few years back after purchasing a book with the subtitle of 'Astrophotography with Affordable Equipment and Software' - the cost of the setup was horrendous!! It was only by chance last year that I came across a Meade 130 plus motor drive from Currys at £150 - made me think again. What a stroke of luck that was. I have enjoyed my initial attempts so much and am probably becoming a bit of an astrophotography bore - just have to tell everyone!

My basic setup (with simple mods) cost : Scope and 1st RA motor £150, guidescope £85, guide camera (webcam) £30, 2nd motor £30, Raspberry PI £35, Canon 1000D (used) £85, various cables etc £40. In all, not a lot of expense. 

The often quoted advice to buy an EQ5 to get into astrophotogrqaphy is of course a solid one - you can't go wrong with an EQ5. But not everyone can afford it and some of us just like pushing the boundaries and learning with something a bit simpler (and lower cost). We don't start off understanding what will interest us e.g. I initially though it a bit strange not to look through a telescope and thought imaging the Pleiades wouldn't be interesting enough - but it is! And I don't look through my scope and more (sorry observing people).

So I vote for including a low cost way into imaging to let people try it out. Note that doesn't necessarily mean easy - it can be easier to spend more and get results with less effort. Depends what suits.

To finish my beginner's rant, I have to add a beginner's M42 of course - a mix of 10 and 45 second exposures to try and stop the core oversaturating. (DSS and GIMP 2.9.x processing.)

[wimvb]

Some of my wide fields. Now (since august 2016) that I have an AZ EQ6 for my scope, I use the EQ3 Pro exclusively for wide field imaging, mostly with my 135 mm Pentax lens.

M31, 135 mm f/3.5 lens on a Pentax K20D, 20 x 240 seconds (unguided) at ISO 1600

M38 & co with the same setup. 43 x 60 seconds at ISO 800

This is with the SW 150PDS (from before I got the AZ EQ6), M3. 17 x 60 seconds at ISO 1600

And the most recent image, M45, 35 x 420 seconds (unguided) with the 135 mm f/3.5 lens at f/5.6, ISO 400

[Peco4321]

So here are my efforts, all with 150p on eq3-2, canon 1100d un-modded, Enhanced motors, but I obviously have to work on polar alignment.  The usual suspects, M42, cropped to show Running Man, M81 & M82, Whirlpool Galaxy, and Double Cluster.

[Stub Mandrel]

Great stuff folks, I've done some 135mm widefield too, not quite as spectacular as Wim's but surprising what you can find and an ideal way for beginner's to learn the ropes with everything being just a little less critical.

[Nigel G]

Great work guy's, impressive images.

 

Cheers

Nige.

[Peco4321]

Leo triplet - 27 x 30 sec ISO 1600 no darks, 30 x bias seeing not great as there seemed to be a lot of moisture in the sky and Leo rising over local town reflecting its light, but this is my 1st attempt at this so quite happy. 

[wimvb]

Great start on Leo. If you have the possibility to increase exposure time (to 60 secs perhaps) and double the number of subs, you will still be under 1 hour total, but have a massive improvement in image quality. Decrease iso if your sky is the limit. 

[Galactic Wanderer]

M42 in black & white. I had pulled out the luminance in pixinsight and was interested with what came through. I still much prefer the color version though

 

 

 

Edited January 25, 2017 by Galactic Wanderer

[Peco4321]

Same night as I got the Leo Triplet, I pointed at the Owl Nebula, and don't you just love it when you get a bonus DSO, in this case M108.  I think having multiple objects in the same image makes for a great perspective.  Anyway, I have so much to learn on processing, but the basics are there and for 22 x 60 sec exposures ISO 800, plus 12 x 30 sec ISO 1600, and 30 x bias, I'm again fairly pleased.  I had polar alignment quite good that night, any tips on processing will be greatly appreciated.

[bobro]

Below is a simple stack - 3 off 10 minutes subs (lights only) at ISO1600 as a test. I hope to image the California Nebula but wonder if 10 minute subs is perhaps a bit too much and that 5 minutes may be better to aim for. Advice appreciated.

[wimvb]

6 minutes ago, bobro said:

Below is a simple stack - 3 off 10 minutes subs (lights only) at ISO1600 as a test. I hope to image the California Nebula but wonder if 10 minute subs is perhaps a bit too much and that 5 minutes may be better to aim for. Advice appreciated.

If 10 min subs @ iso 1600 is too much, why not decrease iso? That should give less noise, and slightly more dynamic range. Somewhere in my collection is an image of the california neb at 4 minutes per sub. It shows the nebula, and I was also able to reveal just the slightest hint of dust. Unfortunately, I had too few subs at the time, and haven't been able to add more data yet. But it is high on my to do list. If you can get guided 10 min exposures, then my advice is to go for it.

[wimvb]

33 minutes ago, Peco4321 said:

Same night as I got the Leo Triplet, I pointed at the Owl Nebula, and don't you just love it when you get a bonus DSO, in this case M108.  I think having multiple objects in the same image makes for a great perspective.  Anyway, I have so much to learn on processing, but the basics are there and for 22 x 60 sec exposures ISO 800, plus 12 x 30 sec ISO 1600, and 30 x bias, I'm again fairly pleased.  I had polar alignment quite good that night, any tips on processing will be greatly appreciated.

Lovely image. Nice to see these two targets together. They seem almost the same size, but one is of course MUCH larger than the other.

Flats will take care of the vignetting. Adjusting colour sliders should clean up the green colour cast, but scnr in PixInsight or hasta la vista green in photoshop work better.

[bobro]

First attempt at the Rosette Nebula - just about recognisable.  Quite a gusty evening - limited length and number of  exposures that were usable. In the end just 12 lights of 4 min at IS01600. Next time...

[wimvb]

... more of the same. Lots more 

It's a good start.

[mikey2000]

Can anyone post their success rate for various DEC and sub exposure lengths?

 

i have the EQ3Pro and with my 150PDS I have to throw away at least half of 45s exposures near 0DEC. Moving up in the sky helps.  E.g., 50% keepers at 85s on m81.

 

My failed subs have either long eggs or sometimes even trails.   

 

I've got quite good at polar alignment so I'm starting to wonder if there is something wrong with my mount or motor.

 

Or maybe everyone else is throwing away 50%+ of their subs....

[mikey2000]

Just to add... I don't have any guiding gear and I'm shooting at 24mpx so maybe I'm being fussy.   I could probably keep a few more if I downscaled to screen size but my properly failed subs are definitely failed - big long streaks.

 

the good subs are pleasingly good though - nice round stars

[Stub Mandrel]

Since getting the 'new style' polarscope, I take 2-minute subs and tell DSS to stack 80 - 90% and let it decide which of them are the best. I only manually remove subs when cloud is passing through or they are obviously awful.

Problems at low DEC suggest it may be that your scope is too well balanced, my subs improved a lot now I make sure the scope is biased one way or the other.

 

[bobro]

Not much chance of taking more lights of the Rosette Nebula due to the weather, so had another go at processing the 12 lights previously captured - a little better. Lots of stars - will need to practice toning them down in order to better see the nebula (when I get more lights!).

[wimvb]

Morphology transformation (MT) in PixInsight is your (/my) best friend for star reduction. Deconvolution would work, if the stars are round and regular. But I've always had more success with MT.

[bobro]

Thanks for the tip Wim - I will look into MT. For now I tried using layers to extract the stars before GIMP processing. Had some success though my effort looks a bit artificial. Practice, practice......

[wimvb]

To be honest, I think the noise you still have will come into the way of processing this image properly. Your best option is to gather more data to bring the noise down. If you can increase your single frame exposure time at a lower iso setting, your data will have less noise.

With this image I would forget about the stars, and concentrate on the nebula. One option you have is to create a b/w copy of the image and process this (mainly noise reduction and some very gentle stretching and local contrast enhancement). Then blur the colour image and do an lrgb combination. In PixInsight there is a function for this. In photoshop/gimp there is very likely a layer blending mode that can achieve the same.

Good luck.

[bobro]

You were spot on Wim! The clouds cleared for a bit tonight, allowing just 7 lights at 8 minutes (plus flats). Using your suggestion of processing a greyscale image and doing an lrgb blend ('value' in GIMP) made for a much better image. Of course more lights will improve it but I'm more than happy with what my simple EQ2 setup has produced so far. A great learning exercise too. Thanks!

Bob

[Stub Mandrel]

Well done Bob, your stars are looking rounder with more data as well.

One sneaky tip for folks like us who haven't got Ha filters: take a colour copy of your image to make a 'lum' image and play with lightening and darkening different colour channels in an extra layer, not worrying about the actual colour.

I find that lightening the red channel can enhance the nebulosity quite a bit, especially if you slightly blur the layer before carefully mixing a percentage of it back with the original.

[wimvb]

For an alternative to the lrgb method that I suggested earlier, here is one that may be more suited for photoshop and gimp. The blending methods may have different names (value instead of color?)

As always, DO try this at home. (As opposed to what they say on tv shows)