M8 using a SkyWatcher SynScan AZ Mount

[sxinias]

M 8, The Lagoon Nebula located in the Constellation Sagittarius taken on 26 June 2011

Equipment:

1. SkyWatcher SynScan AZ GOTO mount and tripod

2. Celestron C6S OTA with a Hirsch 6.3 focal reducer

3. Canon EOS 1000D DSLR

Image

1. 116 exposures

2. 30 minutes 56 seconds total exposure time

3. 1600 ISO

Software

1. Deep Sky Stacker

2. PhotoShop CS5

[Space Cowboy]

Very impressive for a Alt/Az mount!

So each exposure was 16 secs?

I'm planning to try some deep sky imaging with my alt/az auto Dob.

[Shibby]

Great job - an ambitious target for an AZ mount! And is the camera modded?

I see you've had a bit of trouble with vignetting, looking at the way the black point is clipped towards the edges. As you didn't take flats, try using GradientXTerminator (free plugin) if you haven't already. After your first application of curves, run it through GradientXTerminator before continuing. You'll then find you can extract detail from the whole image rather than just the centre.

[Stephen]

Loving the colour of this

Great job - an ambitious target for an AZ mount! And is the camera modded?

I see you've had a bit of trouble with vignetting, looking at the way the black point is clipped towards the edges. As you didn't take flats, try using GradientXTerminator (free plugin) if you haven't already. After your first application of curves, run it through GradientXTerminator before continuing. You'll then find you can extract detail from the whole image rather than just the centre.

GradientXTerminator is only free for 30 days isn't it?

[Shibby]

GradientXTerminator is only free for 30 days isn't it?

Sorry yes, you're quite right - I'd totally forgotten that I purchased it. There is a trail version though, as you say.

[spaceboy]

WOW Great job! You must have some nice dark skies to pull that off with a C6 on an AZ mount. Either that or your hugely talented

[sxinias]

Thanks for the roses.

Photography with a SkyWatcher AZ GOTO mount and its shaky tripod is a challenge. Basically I am curious at what can be done with mounts like it. Last year about this time, I was just starting down the road of astrophotography. I decided to see what a beginner, photography wise, can do with mounts like the SkyWatcher AZ goto, SLT, DS2000, and 4SE. At the time it seemed like a good project to pursue ... and still does as I am having a ball of fun doing it. My C6S or 2045LX3 OTA (4 inch SCT) on my CG5 is where I will end up eventually. In the mean time I am learning a lot of techniques, etc. that I can use. I will also have the capability of "grab and go astrophotography" so to speak using lightweight, portable equipment.

There are a lot of limitations and issues using entry level az mounts for astrophotography. It will never compete with digital images taken with traditional equipment. However, I think that it can be very competitive with the film guys.

At the moment, I trying to use the 4SE mount in the equatorial mode. The mount has one serious design deficiency .... there is no practical way to make fine adjustments in azimuth and altitude needed to do a precise polar align. I've modified the wedge to provide a way to do a fine altitude adjustment but azimuth still requires actual mount movement; a hit and miss proposition. I obtained three minute unguided exposures with it on one occassion but have not been able to repeat or even come close to that time since. Too bad I didn't use that luck on a loto ticket instead. Typical unguided times range from 30 seconds (easy) to one minute (not so often) dependent upon the luck of the polar alignment. The only advantage I see with the 4SE mount in the equatorial mode is that you can do short exposure astrophotography within 30 degrees of the zenith and not worry about field rotation. This in itself is a great advantage over azimuth photography as it does give you the capability to photograph anywhere in the night sky and to photograph where the atmosphere is the thinnest. The 4SE in the Azimuth mode is better than the Skywatcher AZ GOTO (SLT) mount as it has far less vibration issues from tracking and from the tripod with field rotation being the governing factor for most of the sky.

I have also tried Meade's DS2000 mount with a Meade 2045LX3 OTA (4" SCT). I was not able to do anything with it due to the way the mount tracks objects. Hopefully someday I can beg, borrow, or steal a SkyWatcher EQ3 goto and see what it can do. The Celestron SLT mount is so similar to the SkyWatcher SynScan AZ goto mount that I think, but don't know for sure, that the charateristics of the two are the same.

Dark skies, don't I wish. I'm located on the edge of Athens' urban area. However, the sea is to the south of me and when the humidity is low and the moon is not around, this the summer I can some details of the Milky Way as well as a couple of Messier objects in the star cloud with my eyes. After objects pass the meridian, forget it as the light glow from Athens drowns everything except the brightest stars. One good fallout from Greece's economic crises is the local government does not have money to replace street lights when they burn out ........ A year ago, taking any photos from my home would have been impossible due to the street lights and forget about seeing the Milky Way.

The vignetting problem is most likely from the Hirsch 6.3 focal reducer as I don't seem to have the problem when I don't use it. This could be an exposure issue though. However with 16-20 second exposure times, I need as fast a scope as I can get. I'm fairly new at photography and, other than using dark frames, have not yet ventured into other corrections. That's on the list and thanks for the recommendations. I'll certainly look into them. At the moment trying to figure out the mysteries of CS5 is keeping me occupied.

Yes, the exposures were 16 seconds. Statistically 16-20 seconds is about the longest exposure time I can obtain with the SkyWatcher AZ goto mount and have a 80% or so probability of getting a good shot without vibration from tracking gears, wind, dangling camera strap, breathing too hard, etc. I also wanted to reduce field rotation as much as possible. At my latitude, if I stay about 30 degrees away from the zenith, I can get 30 seconds or more exposures with 0.10 degrees field rotation. Unfortunately, this removes a big piece of the sky where the atmosphere is thin for photography.

My camera is a stock Canon EOS 1000D as it came out of the box. One thing I have learned; 100, 16 second shots stacked are not the same as 10, 160 second shots stacked. 16 to 20 seconds is not much time to capture a lot of photons and the exposures are chronically underexposed. I use 1600 ISO even though it adds noise. I had hopped the 6.3 focal reducer would allow me to go down to 800 ISO but 1600 even with the focal reducer seems to do better. I do cull out poor exposures during stacking as they only tend to add noise.

AZ photography with a tracking dob. The wind is an enemy. A lot of sail area to catch the wind. Back focus could also be an issue. However, if you have a DSLR, you are only risking the price of a t ring and adapter. I've seen some shots on one of the forums, I forget which one, where a guy got some neat photographs of some Messier objects with a DOB photographing through the eyepiece.

Here's my M20. Photograph taken on 27 June 2011 with a Canon EOS Rebel XSi (1000D), 1600 ISO. Total exposure time 41 minutes and 7 seconds. Telescope was a Celestron C6S Schmidt Cassegrain Optical Tube Assembly with a f6.3 focal reducer using a SkyWatcher SynScan AZ GOTO mount. I'm thinking about going back and processing it again.