Long Exposure

[robwin]

What is the standard length of time for long exposure from a canon 350d on a HEQ5 mount i have tried 4mins and 1min but still get star trails.

I also have a LX90 10" and have the same problem on that one to.

Is there anyone who can help.

Rob

[Naz]

Is your mount driven? Have you aligned your mount? Otherwise all i have heard you should be ok for a lot longer exposures.

naz

[robwin]

yes it is driven and as for the alignment i just point it north

[SteveL]

so, does that mean "pointing it roughly north", or are you doing real polar align and the drift alignment?

[barkis]

If you are taking one shot long exposure images, you have to have your telescope on a precisely aligned polar mount.

There is not a great deal of room for error, unless you take shorter exposures and stack them, then you will have problems like you are experiencing now. Do you have the LX90 on a wedge?.

Ron.

[robwin]

No wedge for the LX90 would that help

Rob

[centroid]

4 minutes unguided, is asking a lot, if not the impossible from the HEQ5 or the LX90 mounts.

1 minute, should be fairly easy to achieve, with careful alignment, and assuming that the Mount's Periodic Error is reasonable.

Dave

[SteveL]

No wedge for the LX90 would that help

If you are in AltAz (rather han a wedge or GEM mount), then the star trails are probably field rotation, something you cannot avoid in AltAz

[barkis]

Rob. I have an LX90, and I have gradually been gathering stuff together with the aim of using the scope to take Images of DSO's.

I have had a lot of negative feedback on the LX90, some of it on SGL, and also on other astro sites. On the other hand, I have seen some superb results obtained with The LX90 and a DSI Camera, with the scope in Alt Azimuth configuration. So, I have not lost heart.

I have a Superwedge, and the setup will be housed in a run off roofed shed within a month. I will have the scope mounted equatorially on a very solid pier, and I will drift align it until it can't be improved by human endeavour. I am hoping to get a Meade APM Module, which it is hoped, will make the mount auto guidable. That should, after calibrating, testing and getting the goto as accurate as I possibly can.

I also equipped the the setup with GPS, Although I will only need it once for a permanent location. However, it will come in handy if I take the scope to a star party, probably SGL4, I hope. I am doing all the preparations, and taking my time over it, because I know only too well from past experiences, that in this activity, make do and mend is not good enough, and I am not taking any shortcuts, because there aren't any.

Pulse guiding a telescope, used to be done by hand, where the imager would keep the target guide star on the crosshairs of a guide star, located somewhere near the object being photographed. It worked for me years ago, although it is a tedious activity, and can be stressfull. But it is still doable as a last resort.

The pulses that guide the scopes these days are are done by sophisticated equipment, that is very good at what it does.

It still requires a lot of preparatory work, but if you want the results, then you have to do it.

You will get all the answers to any queries you have regarding imaging on this forum, but if you get a good read on the subject, and get an understanding of what it takes to succeed in getting those photons in the right place on your camera' chip, You will find out how much effort you have to put in. It will test your fortitude, and stickability.

Sorry for the long spiel, I tend to rabbit on a bit.

Ron.

[MrEd]

Hi Ron

I have had a lot of negative feedback on the LX90, some of it on SGL, and also on other astro sites. On the other hand, I have seen some superb results obtained with The LX90 and a DSI Camera, with the scope in Alt Azimuth configuration. So, I have not lost heart.

I have had work published by the 'Glossys' with my LX90 in Alt Az.

Even more in the wedge config, So keep persevering it will be worth while.

The LX90 is quite a tame beast when you get to know it.

(and i have no intention of parting with my 8")

regards

Ed

[MrEd]

I also have a LX90 10" and have the same problem on that one to.

Is there anyone who can help.

Rob

Hi Rob

WRT to the LX90, Alt Az will work fine if ......

Train drives (polaris at high mag)

Backlash compensation 10-15% both drives

Latest handset software

Correct tracking rate (Sidereal)

And balance that scope!!!!!

That should give exsposures up to 40 seconds without trails or field rotation.

(Longer mabye if you shoot East or west only)

Any longer you may need to guide (and thats a new can of worms)

Hope i have been of help

ED

[Kaptain Klevtsov]

Hi Rob.

To do over 30 seconds with the HRQ5 you need to use the polar alignment 'scope to get it very close to aligned. This will let you do up to two minutes without trailing. If you drift align you should be able to manage up to three minutes. Any more than that and you have more luck than you deserve or a really good HEQ5.

Check out some links on aligning the polar 'scope, aligning the mount and drift aligning by using the search option. You'll find loads of info to get your head round, some of it written in language that you can understand and some not (or thats how I find it sometimes) but there will be the stuff that you need.

The easy answer is that you need to align the mount more precisely the longer you intend to expose for up to around three minutes. Over that and i think you will need to investigate maual or auto guiding.

HTH

Kaptain Klevtsov

PS If you have no luck searching, give us a shout and we'll find you some links. (just didn't want to point to a load of my stuff 'cos that looks bad)

[robwin]

Well guys thanks for your help i have tried to do a polar alignment today on the HEQ5 very confusing in the instruction book.

Will see what happens and to keep going and dont give up.

Once again thanks for all your help.

Rob

[robwin]

What wedge would be good for the LX90 10".

Any sites where i can read on them.

Thanks

Rob