M42 Orion

[2020BC]

M42 on New Year's eve.

The attached pic is a small section of the original.

To view the original click here (http://www.zodiaclight.com/images/M42OrionSN8mpccCombo1Try1Autoguided 31Dec07Wall1280.jpg) (800 KBytes)

Target: M42 Orion
Scope: Meade SN-8 with MPCC
Exposure: 16x2 mins; 49x30secs; 25x15 secs; 42x4secs
Camera: Canon 350D (unmodified)
Mount: Meade LXD-75 guided
Guidescope: Orion ED80 x2 barlow
Date: 31Dec07
Process: Stack and align in MaxDSLR; Composite processed in Photoshop.

[Matty P]

Great image Bill! Beautiful colour and detail.
A lovely way to end 2007.

[mick pinner]

a wonderful image Bill, great way to finish "07.

[Alchemy]

i like the way youve cropped it. nice to look at

[EzyStyles]

very nice indeed bill. the purple really stands out from an unmodded dslr.

[Garyh]

Yeap a very nice result for a unmodded camera :thumbsup:

[Craig_L]

Very nice shot Bill.

What software are you using to guide the LXD-75 mount? And did you have much trouble getting it to guide? I have a LX55 mount, model before yours and have pretty well given up trying to autoguide. Any advice would be welcome.

Craig

[Ric]

Very nice Bill, the full view is a beauty lovely detail and depth.

Cheers

[2020BC]

Cheers, Craig.

I use the guide function of MaxDSLR software to autoguide the LXD-75.

For this image I used an ED80 (focal length=600mm) as the guidescope with a x2 barlow and a Mintron video camera running at around 0.5 second exposures. Guiding aggression setting was around 7/10. The imaging scope was the SN-8" (Focal length =812mm).

With this setup I can guide well (stars at 100% resolution are nearly round) if I get the balance of the scope correct in both DEC and RA. Using the SN-8 to guide images taken through the ED80 also works well.

A good polar alignment is very helpful. A bad polar alignment makes it harder for the autoguider to keep up. If you have to make a lot of DEC adjustment then the mount won't be able to respond quick enough, the autoguider will send it more DEC adjustments and when the mount finally catches up it will overshoot. Good balance really helps.

Not knowing anything about your mainscope/guidescope, etc. makes it hard to suggest a fix for you, however you could try imaging with the shortest focal length scope and use a guidescope of the same focal length. Use a "non-aggressive" (5/10) setting on the guider to smooth the small/medium tracking errors. This won't do anything about the big bumps which cause the system to lose the guidestar.

If the LXD-55 has PEC (Periodic Error Correction) I'd give that a shot to try and smooth out those bigger bumps.

Also if you sent a video feed to a TV you could supplement autoguiding with a bit of manual guiding to assist the system when it needs it (this requires practice and is a pain).

There's a do it yourself hypertune (www.lxd55.com (http://www.lxd55.com)) for the LXD-55/75 where you get parts and video which shows you how to strip down the mount and rebuild it. The marketing blurbs (and some users on the forums) say that it works great for the LXD-55 and I've heard/read that it can also help PE/tracking on the LXD-75.

Other things that can help:

a) Change your autoguider software so that you make only RA adjustments (switch off DEC adjustments [you'll need a good polar alignment (or image only near North DEC=0 degrees) for this to be feasible]);
b) Change autoguider software to make its RA adjustments in one direction only ( depending on how "fast" the mount is tracking maybe try +x only and switch off -x [or vice versa]);
c) Set telescope weight balance in RA (WHILE POINTING AT THE TARGET) so that the RA balance is 50/50 and then add a very slight imbalance so that weight presses down on the east side of the mount (i.e. the RA motor is always working to lift a weight on that side) so that the gear teeth are always meshed/engaged.
d) Test guiding at North azimuth and zero degrees declination so that the only guide corrections needed will be RA corrections.

[Craig_L]

Hi Bill,

Thanks for your quick response.

I'm still trying to get a better polar alignment but I think I'm pretty close.

At the moment, I am just using the Tak 90 (500mm) with a Neximager to see if I can guide the mount. The LX55 doesn't have PEC but you can adjust the Az/RA and Alt/Dec backlash in % terms - must be the same for the LXD75. 100% according to the manual means it responds immediately while lower values makes it take longer to respond. The settings are in the Setup Menu of Autostar under Telescope. The scope is set at 3% which is how it came - maybe this is too low. I wonder what values these are on your mount?

I've seen the hypertune suggestions on lxd55.com but it looks beyond my abilities.

I will try your other suggestions over the next couple of nights and see if I can get on top of it.

Thanks again for your help.

Craig

[caleb]

what is your focal legnth, diametre and eyepiece and are you usng an autotraking scope. if so it must be prety accurate, unlike myn:whistle:

[2020BC]

Hi,

Details are:

Focal length was 812mm
Aperture was 203mm
Camera was at prime-focus
Mount was autoguided

[leon]

What else can i say Bill, as the others have said, great image, well done.

leon