Pompey Monkey

Thanks for the advice Rob.  

I have bought an A3 LED display for flats and am experimenting with this.  Because of the shutter on the 383 it means that the right amount of light reduction needs to be made to increase the exposure time -  which is a bit fiddly.  Unfortunately the panel can be dimmed but does not dim enough !  Its a question of diffusing the light enough to get to the right exposure I guess. I am also going to look at the T shirt method outdoors but again its getting the right thickness of material to get a long enough exposure !  Bring back AV DSLR flats anyday !

I believe a figure of 25-30k ADU and above 5s should be achieved  to avoid the shutter affect ?

Wrt the coma corrector yes the drawtube focusser scews arent the best and I thought of replacing the complete unit which holds the screws  as it is difficult to tighten the screws with the filter wheel in situ as it is. Haven't researched this yet though.  

From the Atik site the backfocus for the 383 is quoted as 17mm which I assume is from the chip to the 383 mating interface - I guess this is the distance I add to the EFW thickness and then add the CC internal distance to the lens and then also add a spacer if required to get 55mm     Does this sound about right to you ?

I've had good results with ADUs in the range 14,000 to 30,000. I don't think that it's mega-critical as long as you are well out of the noise floor and not saturating the sensor. Flat field corrections in software are multiplictive so, in theory at least, as long as you are not clipped at the black or white ends the corrected results should be the same as long as the sensor is linear. The KAF 8300 is, apparently, quite linear and is used for scientific work.

With regards to the back focus distance, you'll have a fun time sourcing all the spacers that you'll need to get it exact. I found Telescop-Express to be a very useful resource.

The third screw in the eyepiece holder is an absolutely must with the weight of the coma corrector, filter wheel and camera hanging off of the PDS focuser if you want any kind of orthogonality at your chip! I used an M6 allen-head bolt that I have in abundance. There's plenty of metal in the eyepiece holder to take the bolt. Taps and dies are cheap and you just need to find a buddy with a pillar drill (every astronomer should have access to a pillar drill! ). You can see the bolt in this close up:

You might also consider tightening up the focuser a bit too. See here: http://www.teleskop-shop.at/testphotos/w-erbung/Crayford_adjustment_Synta_microfoc.pdf I found that the weight of the imaging gear would slowly unwind the focuser over the evening until I had "corrected" the tension in mine.

I recently bought the Hitecastro unit and it doesn't work, despite spending hours faffing with drivers and support from the vendor.

Today I spent ten minutes crimping an RJ45 connector (based on the EQMOD website instructions) onto the cable of one of these ftdi adapters: http://www.ebay.co.uk/itm/301820203340?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT and it worked first time.

Prolific vs ftdi? Go figure! lol.

And another closer one: M45

Image stacked in DSS from 33x3 min subs at ISO 1600 with Canon 500D. Post processing in StarTools and GIMP.

M45BProc.jpg

Very nice, but I think there could be a lot more detail in there if you relaxed the black point a little.

uranium, 

no, it is unguided, the 9x50 finder haven't arrived yet.

the image was shot without the cc, sky was cloudy all night and about 2 a.m it cleared so i went to image a bit.  i need to give the cc a go one of these days.

do you have any idea about the random trails? this is how it is:

L_0031.JPG

the above one is ok for me, but then i get something like the one below all the time

L_0032.JPG

thank you.

Hi Atreta,

This looks very much like periodic error: many unguided subs are OK, followed by some that are completely elongated!

Guiding with a finder guider, especially if you use PEC in ASCOM, will all but eliminate this problem.

Paul

PS I send you a PM

I didnt realise these objects would photograph in natural colour

gobsmacked

When you see that the first sub in a run has colour in it, you know it's worth all the pain getting there!

Coming along nicely. And giving me ideas as to how to continue my roll-off shed

Doing this can introduce signalling delays. EQMOD is designed to work with a direct connection to the mount, not through the handset.

When troubleshooting always try and remove as many variables as possible....perhaps the 20m cable and handset connection are part of the problem?

I'm not the one having the problem!

are you using EQMOD, or an Ascom driver ?  If a driver, do you know which one ?

EQMOD and ASCOM

I just followed the instructions on the EQMOD page. I use the same setup for my HEQ5. The only driver issue that I recall was associated with my QHY5.

yes, I noticed that, but then I think that's because it's not crossing the axis at all, but is always trying to pull back towards it, so not oscillating around the axis.

I need to do some more experimenting - at the moment, I'm thinking that connecting ST4 should see me right.

Pompey, how are you connecting your pc to scope, if u don't mind me asking ?

I go via the SynScan handset. I'm too much of a skinflint to buy the HiTech cable

I don't use the ST4 port on my QHY5, I just let PHD do the work on the laptop.

Interestingly, I am using a bog-standard Cat 5e cable from the handset to the mount. I can confirm that this method works for at least a 20 m length.

i have the same mount i couldnt get phd2 to work same sort of graph ,went back to phd1 works perfectly, i can go 30 min subs 

mark

I set up my new AZ-EQ6 GT on Friday night with PHD 2.5 and it worked absolutely fine.

.....Until I started experimenting with the dither function in APT. But that's another story. LOL

I have a 500d that I will astro modify and I will see how far I can go with that from my suburban skies (probably about Bortle 5).

Whoops! I have Bortle 7 skies - the "5" is for the local dark sky site that I have access to maybe a couple of dozen or so times a year.

When you say sharpness, thats a bit of an open question because the there are quite a few things that contribute to the sharpness/contrast of an image, examples being:

1) Resolution: This is determined by the cameras pixel size, and the focal length and resolving power of the telescope. Its unlikely that you will find a pixel size small enough to oversample the 130, most DSLRs will yield roughly the same results.

2) Good data: That is data taken with good guiding and conditions (no clouds, no moon), long subs.

3) Processing: A fair amount of the contrast and sharpness is won back at this stage. You cant expect a newt to be as contrasty as a frac (eg: an 80ED), but where is does win out is with the depth of the data you have from running at f5 (can therefore stand up to more processing). 

4) Collimation: Better the collimation, better the image

Yes you need a coma corrector if youre going to do anything serious with it, but when you ask for pinpoint stars - that wll be down to you and how you handle the telescope (ie: collimation etc). Its perfectly feasable to get  a good field without much effort, but if youre asking for 100% perfect in each corner of a big chip (what I call "the last 1%") - thats a bit more difficult.... it depends on how demanding you want to be.

I'm loving this thread! I have a 150P-DS which is very similar to the 130.

I've done a handful of images on an HEQ5 with PHD on a tripod, but I'm in the process of building my roll-off shed obsy with a AZ-EQ6 mount.

I have a 500d that I will astro modify and I will see how far I can go with that from my suburban skies (probably about Bortle 5).

Eventually, I will go to the dark side proper and get a CCD (hopefully a 8300 based set-up).

But, for now, the game for me is to refine the process and understand how to push along that asymptotic curve to "perfection" i.e. that last 1%. Advice like the quoted above is priceless!

I reckon I still have about 98% to go!

It's top of the list for me   And in fact, the only cause of dead DSLRs.

I've been dipping into this thread since my love of astronomy has been rekindled by modern AP. I am seriously tempted to kill debayer the sensor in my 550D (if the Ebayer ever sends it) too!

Edit: Ebayer/debayer? Coincidence? lol.

sssssh.... you'll convince me if you're not careful....

Oh noes!! It has <Mysteriously> disappeared from the astroboot website...

Gonna set my Dremmel on my Revelation 10" in the near future. Sorry 130'ers, but photons rule the day!

I'm not affiliated with them, but Astroboot has one for £110 at the moment - full 12 months warranty.....

It's almost worth buying for the dual-speed focuser alone at that price...  

Oh well, lets take the plunge. My first ever DSO, on my second outing with my new (secondhand) equipment. 

Another M42 10 fifteen second exposures at 6400 ISO, a handful of darks and bias frames. No flats as I forgot to take them before taking the camera off the 'scope. Orion was rapidly sinking below the houses and it was so murky that we could barely see the belt with the naked eye. Process with DSS, IRIS (thanks to the Astronomy Now tutorial) and levels tweaked in PS.

I'm happy

Damian,

You are an inspiration to every fledgling and wannabe mirror-maker out there! I may even be tempted to make my own one day.

Good luck with the figuring process!