For those who owns LXD55 and LXD75

[VinSnr]

The latest autostar version has PEC for LXD 55 also!

For LXD75, I think it comes ready with PEC controls.

So LXD55 owners, you now have one new feature in your autostar! Might be useful when you do astrophotography using DSLR.

[kingkong]

from what i've seen in the lxd55/75 forums, people have been doing real good without the pec feature - often after the mount is tuned.
i'm not sure but i suspect autostar doesn't store the pec training after power off. if that's true, one will have to do the pec training every session which can prove more trouble than is worth if the mount's periodic error is not that bad.
while unlike more expensive mounts that works fine out of the box, the lxd75 mount often need tuning save a few lucky ones, but afterward its performance impresses a lot of people.
i've not done any astroimaging on mine yet because as a gem newbie, i'm still learning to polar align my scope properly, and i can't do drift align without a reticle eyepiece. perhaps my mount still needs some fiddling too.
i still have no time to do a half pier good enough for imaging.

[VinSnr]

from what i've seen in the lxd55/75 forums, people have been doing real good without the pec feature - often after the mount is tuned.
i'm not sure but i suspect autostar doesn't store the pec training after power off. if that's true, one will have to do the pec training every session which can prove more trouble than is worth if the mount's periodic error is not that bad.
while unlike more expensive mounts that works fine out of the box, the lxd75 mount often need tuning save a few lucky ones, but afterward its performance impresses a lot of people.
i've not done any astroimaging on mine yet because as a gem newbie, i'm still learning to polar align my scope properly, and i can't do drift align without a reticle eyepiece. perhaps my mount still needs some fiddling too.
i still have no time to do a half pier good enough for imaging.

Those guys didn't have much problem because I think they do guiding. Either through off axis guiders or a guiding scope. And of course, with them able to see Polaris, their alignment should be quite good without wasting too much time.

But for us you might not want to waste too much time doing drift alignment. Rough alignment works for the LXD55/75, and it will be good enough for visual. But for photos, even 30 seconds will leave star trails.

So this is where you might want to use PEC for 1-2 minutes exposure doing DSLR imaging. Also, you have to take a lot of shots to stack, so it will be a pain to guide this 1-2 minutes for so many times. If PEC can average out the error, then you can let PEC do the job for you with reasonable accuracy for just a minute or two.

With PEC you still need to have a good alignment, but at least you have something to help you minimise the error.

[kingkong]

Those guys didn't have much problem because I think they do guiding. Either through off axis guiders or a guiding scope.

these links have examples of unguided images taken on lxd55/75:

http://www.cloudynights.com/ubbthreads/ ... ain/252032

http://lxd55.com/astrophotos/ViewPhoto.asp?Photo=776

http://lxd55.com/astrophotos/ViewPhoto.asp?Photo=777

http://www.weasner.com/lxd/astrophotogr ... epsky.html

http://www.mackayphotography.co.uk/deep_sky_objects.htm

i was surprised when i first saw them.
of course, may be i should take what i see on the net with a pinch of salt

[VinSnr]

It is possible provided you get a very good alignment. For them it's not too difficult because they can use the polar scope and align close to Polaris.

For us it will be a lot of effort. Even getting the initial alignment was a headache. I have lost count how many times I got "alignment unsuccessful" before I got one that is successful. If you can spend all the time doing drift alignment, then surely there is no need for PEC, unless it's a super long exposure.

If you ask me, I rather just do a rough alignment, then use PEC to half that error. I find it easier and quicker, unless someone does the drift alignment for me and I just sit back and look...

[kingkong]

If you ask me, I rather just do a rough alignment, then use PEC to half that error. I find it easier and quicker, unless someone does the drift alignment for me and I just sit back and look...

please forgive a newbie, but i thought drift alignment is to deal with alignment errors while pec is to deal with motor/gear errors hence one doesn't really substitude the other.

[VinSnr]

If you ask me, I rather just do a rough alignment, then use PEC to half that error. I find it easier and quicker, unless someone does the drift alignment for me and I just sit back and look...

please forgive a newbie, but i thought drift alignment is to deal with alignment errors while pec is to deal with motor/gear errors hence one doesn't really substitude the other.

yes you are right.....very good that you can see that.

Yes, you still need reasonable alignment before you can use PEC. PEC is not gonna help you much if your alignment itself is bad.

When i use the word rough....it means "rough" as compared to a wonderfully done drift alignment. But even that you need to face worm problems..hence PEC if long exposures.

But If I am willing to do say only 80% of a good drift, and I spend other time doing PEC to eliminate the worm problem, then most probably my results is comparable to the guy who has 100% good drift + worm problems.

Sometimes it's that last 20% of perfection that took enormous patience and time.

[kingkong]

ok. i understand though i can't really relate since i've never done a drift alignment before.
neither have i perform a pec training yet, but just from what i've read about drift alignment procedure on the net and about pec in the lxd75 maual, i don't think the pec is going to be any easier to do than drift alignmnet.

[anat]

I am very new to the drift alignment. Last week, I did drift alignment with Aldebaran when it was the star near the horizon until it was at the meridian hahaha I think that PEC training should be done after doing a precise drift alignment. If not, alignment error will be included in the correction. Am I correct?

[VinSnr]

ok. i understand though i can't really relate since i've never done a drift alignment before.
neither have i perform a pec training yet, but just from what i've read about drift alignment procedure on the net and about pec in the lxd75 maual, i don't think the pec is going to be any easier to do than drift alignmnet.

Well..drift alignment you need a lot a lot of patience. It's constant adjustment to make the error smaller and smaller. Once you get one axis right, you will need to do for the other axis. Let's just say it's not a fun thing to do.

For PEC, you only do one axis..the RA axis. All you need is high power reticle eyepiece. Put the star at the centre and guide it for one full cycle of the worm (normally around 8 minutes). That's all. The computer will remember your "training" and will "playback" your training during the real photography session.

If you ask me...I rather do PEC anytime. But before you can do that, your alignment must be already pretty good enough. You still can't escape drift alignment. The only thing is, you can minimise some effort on the drift alignment part if you have PEC feature. If you don't have PEC feature..then you got no choice but to spend all the time in getting the drift perfectly right and hopefully the worm doesn';t give you too much problem later. (that's why mount with super small PE error, say around 3 arc secs is very expensive!)

Now how much more time is required if you do a 80% drift alignment and a 100% drift alignment? Can be quite a lot. Squeezing that last 20% can be very time consuming. A high power eyepiece will help hasten a lot here.

It's like making a mirror. Going from 1/10 wave to 1/20 wave might not look a lot, but the effort of fine polishing is enormous.