parallaxerr

1 hour ago, The Admiral said:

From looking at many of the offerings on this site it does seem to me that the image processing is as critical a part as getting the data in the first place

Agreed. As it happens I came across this post just after posting my image...

Although it was taken on an EQ mount with a little more aperture and longer subs, it's only about 60% of the exposure time of my attempt. Definitely think there's more processing required. One issue I find with my images is a complete lack of colour, they're almost B&W after stacking.

Also, some peoples images show far more detail than mine post stacking, before being processed?

EDIT: Just re-visited my RAW light frames and I've noticed a good proportion have cloud cover. I didn't notice last night when adding them to DSS. I assume DSS rejects these, is there a way to find out how many were actually stacked?

Had a reasonably clear last night so had a second stab at M31.

I've got to grips with the Auto Two Star alignment via camera live view much better now. I found a grid overlay option which allows me to put the alignment starts absolutely central  and I then carried out a precise goto align on Mirach as suggested by the mount. After slewing to M31 I took a few subs to confirm alignment and it was very good.

I stepped up to 30secs exposure this time as per Ians suggestion, accepting that I would lose some subs to trailing. In total I captured 225x30s lights + 50x30s darks. Flats and dark flats were carried out prior to lights, 50 of each.

Total light frame capture was limited due to physical camera/mount interference at 60° Alt. My setup is still tail heavy so come payday I'm planning on getting an ADM dovetail to shove the whole lot forward so it balances better and will increase available alt. I did note however how the mount accelerated in alt later in the session and field rotation got faster.

Threw the whole lot into DSS about 11pm and went to bed. Had my stack waiting this morning so put it through ST and got the image below. Much better than last time, calibration frames certainly reduced gradients & vignetting. Still finding ST a little clunky, so just got a trial licence for PixInsight and will have a play with that over the next month or so.

Yeah the lights went off and the blinds were closed for exposures, this was just for show

Forecast clear, clouds slowly disappearing, flats in progress, fingers crossed...

4 hours ago, Stub Mandrel said:

Just for comparison, I've got a quad-core 3.4 GHz machine with 8gig of RAM, which although it sounds impressive is far from exceptional these days. As an experiment, I've just done a stack of 159 lights, 154 darks, 36 flats and 70 bias frames from two sessions. DSS took 1 hour and 18 minutes, hardly instant but worth the wait for three hours imaging time.

I've just had to buy a 12GB triple channel kit for my i7-940 quad-core. Star tools is the first program that's maxed out my current 6GB!

Ah that's a shame Kat, I got it @ £7, maybe it will come down again. I've noticed kindle book prices jumping around before.

1 hour ago, The Admiral said:

with your even shorter focal length the mount should easily give you 30s. Don't expect to see no star trailing though; I find a percentage show it to a greater or lesser degree.

Good to know. Admittedly I saw some trailing in the first 30s exposure on the camera screen so reduced to 20s. It could be that the tracking was lagging as the mount is set to approach up and right whereas I may need to set right and down to keep the alt gear loaded after slewing, due to being tail heavy. Worth a try.

1 minute ago, Nigel G said:

I just did a quick gradient wipe with ST

Interesting Nige, I tried it and got a different result, will retry with the original file.

Perfect timing Ian, I just spent the last hour trialing Star Tools and came up with the image below. I followed a simple tutorial (which left plenty unexplained), however I'm amazed at what the program has brought out in the image. Considering the major lack of subs here, I'm impressed and will buy a licence for ST, it will be interesting to see what it can do with more photons!

P.S. Low res screen grab!

Thanks Nigel - I must admit I'm very happy with the way the setup looks. I like my equipment to look good as well as perform well, although I don't think I'm alone on that one.

Fil - Wow!!! OK so there's definitely more information in there than I thought and you make a very strong case for post processing, another steep learning curve coming up I feel.

Thanks for the comments guys...

I am pleased with the stars Ian, the Bahtinov mask & live view made focusing very straight forward and the focus point is about 9mm from the end of draw tube travel. I don't know GIMP either but I lost my copy of Photoshop CS3 when I changed to an SSD hard drive recently, although I never really got on with it. Good point on the camera strap, I'll fit it, or perhaps add a little paracord tether to the mount, just in case.

Steve - the Giga-T is very easy to use. You can set delay, exposure duration, interval etc. all very easily then just press play and off it goes (camera has to be in bulb mode). I kept an eye on the exposure count from the warmth of the kitchen watching it count down

Well, as can be expected the cloud has rolled in. I managed to get about 13 minutes of M31, mostly through a light haze of cloud. However, I'm happy to say that, I just took my first bunch of Astro images AND, I just tried my hand at DSS & GIMP for the first time.

It's been a valuable first night of trial and error. I saw some star trailing on 30s exposures so reduced to 20s which got rid. The Baader multi-purpose coma corrector does indeed work well with this scope, the stars in the corners of the images are elongated only a touch, hopefully I can adjust this out by tweaking the sensor spacing.

So here it is, output from DSS (light frames only) and another with curves adjusted (a lot) just to see if there's any hint of spiral arms, and there is Absolutely school boy in comparison to the other images in the thread but I've made a start!

Tadaaaaaa!!!

Here it is in all it's glory, my Alt/Az imaging rig! Really pleased so far with how this has turned out, it's a very compact, neat little setup.

Few issues:

1. The Baader SCT to 2" click-lock doesn't have a shoulder inside for the draw tube to contact so it can be tightened. The adapter just screwed straight past the end of the draw tube and became loose and free to move fore and aft
2. It's all very tail heavy as the L-bracket dovetail allows for exactly zero adjustment due to it's short length.

Work arounds:

1. Fitted a 7mm 2" extension to the snout of the MPCC and inserted it into click-lock and did it up TIGHT! Then screwed the click-lock onto the draw tube so that the snout extension now becomes the physical stop. Seems to be working OK, I guess the original WO adapter had a flange/shoulder inside for a stop.
2. Rotate focuser 90° to get as far forward as possible & try it as it is! See what happens, the scope will be loaded against the Alt main gear quite a bit so hopefully it will track OK. Otherwise may need an ADM type dovetail extension.

Took it all outside and set it going on M31, it's snapping away right now on the Hahnel Giga-T II Pro wireless intervalometer, which I can program from in the kitchen Very easy to handle and a breeze to align with the RDF and live view on the camera. Focus spot on with Bahtinov mask...let's see what comes out in an hour or so!

28 minutes ago, The Admiral said:

But more importantly, I can't help noticing how clean and clear your desk is .

Haha, I wish that were the case. It took me a good 5 minutes to clear a space to take that photo

Woohoo, bits have arrived Bahtinov mask, Baader SCT to 2" click-lock, Baader MPCC and Nikon T-ring.

Should have camera mounted to scope tonight, just hope there are no focussing issues. Should be OK for spacers if I need out-focus but in-focus is the main concern, however, the website I took the MPCC recomendation from didn't mention any issues with the WO ZS66 so fingers crossed.

Scope balance/weighting.

Guys, when seting up for Alt/Az imaging, are you biasing the weight of OTA and camera one way or another? I have read the EQ guys weight towards the East, I'm guessing to keep the mount geartrain loaded in the direction of tracking.

Thus, I assume biasing the weight toward the objective end is preferable as the Alt axis is driving up when pointing East? Would you bias toward the rear when pointing West?

32 minutes ago, SteveNickolls said:

If you haven't already had a look at the book by Joseph Ashley, "Astro-photography on the Go Using Short Exposures with Light Mounts"

Thanks for the welcome Steve, I'll look into the book, see if I can download it for Kindle.

Edit: That didn't take long!...

39 minutes ago, The Admiral said:

Welcome Jon, I'm glad that you've come over to the 'dark' side! It is true that clusters tend to be easier because you are not dealing with feint nebulosity and you can get away with a shorter total exposure, but there are many clusters and only one M31 . My advice would be to give it a go while you have the chance; it is big and fairly bright, so in that respect it is probably one of the easier galaxies. And of course, provided that you get your subs, then you can re-visit as your processing skills improve. After a while you may feel that you can do better, so the next time it comes around you can be fully prepared.

Cheers, Ian

Well there's a challenge if I ever heard one! You are very persuasive Ian I'm sure I'll be on M31 sooner rather than later!

Rock solid. I only mount small fracs up to 120mm on it which are well below the design payload. I have no concerns over stability.

2 minutes ago, Herzy said:

Sorry to kill your fun, but you don't quite have your priorities straight. The images in this thread are great, but there is a limit to what you can do with an alt/az mount. While the limit is still pretty high up, and you may be able to be satisfied with your images for a long time, if you decide to really get in the hobby a mount like this won't get the job done long-term. 

As most astrophotographers will tell you, 50% or more of your budget should go towards your mount. Your mount is the most important piece. It is really important because even 1/1000 of an inch of error in tracking the sky will give you trails. It's hard to imagine how precise you have to be. If the mount is so important, I wouldn't advise you to buy something that won't last you long-term. I'm sorry, but that's the truth.

I use to be an alt/az user so I still read and participate in this thread as I know the struggles of this kind of mount. I believe that this thread should be used as encouragement for those who ALREADY have an alt/az mount to not give up or be disheartened. It should NOT be a thread advising people to get one over an EQ mount (unless your planning on wide field work).

Again, I'm not saying that you won't make cool images with a setup like that. I'm just saying that if you have the choice right now to choose between an EQ mount or an alt-az, an EQ is the way to go. 

I DO already have an Alt/Az - the Nexstar SE. That's the point, I'm just having a go with what I've got!

Just now, Filroden said:

Welcome Jon. That WO66SD should give a nice field of view. Can't wait to see your results. Do you have some targets in mind already?

Thanks for the welcome, as it happens I just punched the scope and camera data into FOV calculator and got this...

M31 is nicely positioned for me at the moment but I want to learn to walk before I can run! The double cluster in Perseus is one of my favourite visual objects and nicely positioned too so should be a good target to start with. Being brighter I hope to get away with less/shorter subs and test my hand at DSS.

Hi everyone,

Well, I've just finished reading the contents of this thread and I must say I'm thoroughly impressed with the quality of images here! I never thought it would be possible to creat images like these with the sort of equipment being used, I have obviously been brainwashed by the EQ only crowd

I was pointed in this direction when @happy-kat put me onto @The Admiral after disussing something about my Nexstar SE mount in another thread (I forget exactly what, now). Having spoken to Ian via PM I found myself being gently encouraged to have a go at Alt/Az imaging.

So...this is to say hello and I hope to join the party soon, as I've placed an order for all necessary bits to get my camera on the end of a scope (highlighted blue below)!

My setup will consist of:

• Celestron Nexstar SE 6/8 mount
• William Optics Zenith Star 66SD doublet Apo
• Baader SCT to 2" click-lock
• Baader Multi Purpose Coma Corrector (proven to work rather nicely with the 66SD here - http://www.stark-labs.com/craig/WO66SD/WO66SD.html)
• Nikon T-ring
• Nikon D3200 DSLR

Here's to hopefully contributing my first images before too long and quizzing you all on exactly where I'm going wrong! Looking forward to this little foray into imaging!

Jon

1 minute ago, Chris Lock said:

Very nice big brother to mine  Lot's more room on the 6/8SE version by the looks of it, and the Moonlite sets the whole thing off a treat

I've set an Alt limit of 75 degrees on the handset so it hopefully won't suggest objects above this, I don't want to crash into the mount! 

 

Ah 75° is fine, the handset will make suggestions above this but give you a slew warning if you try to goto them. I'm restricted to 62° before that pesky compression ring screw on the moonlite contacts.

Just realised you have the built in wedge which could help get around the Alt restriction, apart from when pointing N. I'm tempted by the wedge for mine as it should allow the scope to go past Zenith on the S meridian.

Big brother to Chris's setup

ST120 on Nexstar SE6/8 now updated with moonlite.

Despite the Alt restriction, I think you'll enjoy that setup @Chris Lock, very grab & go. I was tempted by the same scope before realising the 120 would fit.

Hi Knighty, the wrap is Carbon fibre effect vinyl from eBay. Not sure which seller I used but there's loads on there selling it.