Request for comments

[whzzz28]

I had my first successful night out last night, after waiting two months for Brisbane weather to be nice enough.

I amazed myself by getting the mount, to what i thought was, aligned within 30mins (drift aligned).

Was able to take some 5min shots without star movement, but it was not without its problems.

Some specs:
Scope: Meade 5000 80mm refractor (ED, APO, triplet)
Mount: HEQ5
Camera: Canon 1100d (modded)
Guidescope: Orion ST80 + QHY5
Software: PHD, Nebulosity, Stellarium, EQMOD

I am not sure what exactly is causing my issues - bad equipment, incorrect settings or bad eye's; so i thought id ask.


Two months ago i took a shot of M42 with poor/next to no alignment (limiting shots to a few seconds) - but i was able to see a problem not completely caused by lack of tracking/proper alignment: elongated stars.
I was not using a field flattener, and the stars are only on the outer image so i thought the lack of flattener was the problem. Thus i purchased a Hotech field flattener: http://astroshop.com.au/products/docs/hotech-field-flattener.pdf
Can see the image here: http://core-au.net/astro/m42/m42.jpg

Last night i grabbed some shots of mainly clusters, with the field flattener on. The problem was reduced, but the elongated stars were still there; however i noticed that the problem seems to mainly exist on the right hand side of the image. The left side looks relatively OK.
For example, IC2944: http://core-au.net/astro/ic2944/ic2944.jpg
Is this a lack of flat field problem or something else?

On to problem two.
I use Nebulosity to do focusing and choose a star at random in the FOV, normally looking for a medium/smallish star.
I try to get the HFR to the lowest value i can, and last night i was hitting 2-2.5 most of the time. Is this value acceptable or will this be considered too far out of focus?
Reason i ask is i noticed my stars are more so blobs rather than pinpoints. Compared to images i see around, my stars are round and blobby, and the longer the exposure the blobbier they are. Other people's stars remain smallish but gain the halo-ish star affect. Maybe i am just being pedantic and this is perfectly acceptable.
Is this simply a problem of my focus being out, the scope, the camera or is my tracking/alignment out?
For example: NGC6231: http://core-au.net/astro/ngc6231/ngc6231.jpg
(note: image is large, it is full size)

Problem three:
Tracking with PHD was working fine, worked all night, however i noticed the graphs were a bit strange. Wondering if my settings aren't aggressive enough, or could it be slop with the mount or something else?
This doesn't occur all the time, just randomly.
Example where it is running fine: http://core-au.net/astro/tracking3.png
Example where it starts to lose it: http://core-au.net/astro/tracking.png

Problem four:
I am getting blobs on my images. I am going to hazard a guess that it is dust, but i can't find out where it is coming from. Given the large smudges, i guess it is probably very close to, or even in the camera's sensor area. The longer the exposure, the more annoying they are.
If anyone has any theories, i'd love to hear them.
m8 raw, can easily be seen: http://core-au.net/astro/m8/dots.png
m8, can see the black spots: http://core-au.net/astro/m8/m8.jpg

On a side note, after processing M8, i realized i need to spend much more exposure time on it. Oh well, it was closing in on 2am - and was freezing last night when i took it.

If there is anything else people have seen, things i should be working on, please let me know.

Thanks.

[2stroke]

1&2 Take a few shots around your home and check with a 18-55mm lens on. If that checks out grab your 80 and takes some shots of distance things, i think your focus er may have to much play if it gets to this stage. Work in the daylight and rule out one thing at a time, this way your taking the guess work out out of things. Check your T-ring and tighten the micro grub screws to and look for play between camera and scope.

3 Maybe its just drive problems, not an expert at all but is PEC enabled?

4 dust, oil from finger or could even be glue off gassing resiude, have your try'd a sensor swab ? Have you done any flats to check this out, may give a clear image of what it is.

[bmitchell82]

Jay has pretty much hit the nail on the head

If you want to see if you have tilt. Focus your camera in different parts of the screen. aka, top left bottom right. if you indeed have tilt then it will show up as where you focused is sharp and everywhere else you have egg stars. Be aware most flatteners/correctors/reducers are sensitive to placement/collimation.

Re: your star sizes, they are perfectly acceptable. Bigger/closer stars will appear bigger in your image.

here is a photo of my 40d and ED80 here (http://brendanmitchell.net/?page_id=10&wppa-album=22&wppa-photo=31&wppa-occur=1) and here (http://brendanmitchell.net/?page_id=10&wppa-album=22&wppa-photo=48&wppa-occur=1) and here (http://brendanmitchell.net/?page_id=10&wppa-album=22&wppa-photo=49&wppa-occur=1)

Also have a look at my guide for setting up EQ mounts focusing on Synta brands here (http://brendanmitchell.net/?page_id=213)

[2stroke]

Just seen your also running off battery power and not wall outlet try this as it may help for problem #3 Brendan who posted above does tune up's for these mounts to help take periodic errors out this would be also help out alot. I have read of metal shavings and fillings being found on the worm & gear this would result in the mount jumping so radically. If your a diy self person you could to a clean and re-grease, if not send it off to him as by the looks his got an art for it. He also adds shims and does a very nice worm alignment at a more then fair price and a few other fix's, not selling his service but if you aren't confident i would send it to him.

Disable theUSB selective suspend option. To do this, follow these steps: 1. ClickStart, type power options in the Start Search box, and then clickPower Options in the Programs list. If you are prompted for an administrator
password or confirmation, type your password or click Continue.
2. Under the selected power plan, click Change plan settings.
3. Click Change advanced power settings.
4. In the Power Options dialog box, expand USB settings, and then expandUSB selective suspend setting.
6. If you want to disable Windows 7 to turn off the USB root hub click Disabled in thePlugged in list, and then click OK
If that doesn’t help, then I would suggest you to create a new power plan and check if it fixes the problem.
Refer these links for help:
Change, create, or delete a power plan (scheme):
http://windows.microsoft.com/en-us/windows7/Change-create-or-delete-a-power-plan-scheme
Power plans: frequently asked questions:
http://windows.microsoft.com/en-us/windows7/Power-plans-frequently-asked-questions

[whzzz28]

PEC was not enabled, will have to make sure i enable it in EQMOD next time.

After last nights more attempts, in which i took a few 10min subs, i have found more dots on the screen, which are bought out nicely here:
http://core-au.net/astro/m83.jpg

I havn't touched my scope's optics at all, so i am guessing the camera sensor may be dirty. I will try swabbing it.
The scope however, which i purchased brand new, does appear to have been used before i received it. It has dust inside the air compartments and the focuser looks slightly worn. I should have sent it back to Bintel when i saw it, but thought it would be fine. I hope the marks are not on the scope - else i will be disappointed.

I will also try the camera ideas.

With regards to PHD - i believe i have sorted that.
Had problems last night where it would track for a min or two, then Dec would start losing it and the graph would show dec climbing until it went off scale.
After playing with settings i found the Dec timer needed to be increased from 300ms to 500ms. Once i did this, tracking was very smooth.

Cheers all.

[naskies]

Quick way to check if its due to the camera vs scope: take a photo through the scope, rotate the camera, take another photo.

If the dust spots are in the same location, it's probably dust on your camera sensor.

If the dust spots move (but are in the same relative position to the nebula/galaxy in the photo), then it's probably something in your scope.