To wedge, or to de-rotate... this is the question...

[chrisc]

Hi everyone,

I'm soon to become the proud owner of a shiny new 8" LX200-ACF, and as I would like to take some deep sky photos with it, I'm going to need either a good quality equatorial wedge, or (and I only just discovered they exist) a de-rotator.

Given that the current price of the Meade Ultrawedge and the Meade field derotator are very nearly the same, I was wondering if anyone would care to offer an opinion as to which is the more sensible option?

I'm currently using a little 130mm Newtonian on an EQ mount, and so am at one with the pain of polar aligning every time I take it outside... thus please don't feel the need to let the "he should suffer through polar alignment like we all had to" factor influence your decision. :-)

The third option would be the "non-ultra" Meade wedge... at about a third of the cost of an ultrawedge or derotator, though I worry the build quality is somewhat inferior.

Thoughts??

Cheers,
Chris
:)

[bmitchell82]

to be honest with you. a wedge is 100% the way to go. if you run in alt az mode you have a few things playing against you. your tracking virtually in 3d that is the alt and az motors have to work the same. secondly your derotator has to be spot on just another thing that can go wrong!

if you have the skills make the wedge yourself they are very basic pieces of kit to fabricate.

[[1ponders]]

As a previous 8" LX200 owner I agree with Brendan. Go the wedge. If you can afford it go for the ultra wedge. The standard wedge really is too light and the Azimuth adjustment mechanism on it suck (to say the least).

I've not used a derotator, but you can't do piggy back using a derotator. I'm also fairly sure that even with a derotator there are some areas of the sky that don't work as well with it. :shrug:

[Mighty_oz]

Good Q i don't have one but this site http://www.mapug-astronomy.net/AstroDesigns/MAPUG/ArhvList.htm
may help, lots of info for u :) Re the wedge goto bottom right section Obs's wedges etc.

[Ric]

Hi Chris, definitely go with the wedge option. You will be happier in the long run.

I use the ultra-wedge and as yet have not encountered any problems in it's use. Eventually I'll mount it onto a permanent pier when the Obs is built (sometime in the near future with a bit of luck).

cheers

[marki]

Get the wedge unless you intend to buy a really expensive de-rotator, the meade unit is not the best and needs a lot of modification to make it work properly.

Mark

[bojan]

Wedge rules.

[higginsdj]

Alt/Az and a De-rotator will work just fine - BUT - you now have 3 drives trying to stay locked to a target instead of 1. ie you are adding complexity to a setup that you can more cheaply and reliably avoid. The Pro's use Alt/Az and derotators simply because it is a cheaper/the only option on large scope.

Cheers

[Merlin66]

The Meade derotator works well and does what it says on the box.
The added distance behind the rear cell can cause issues with access near the poles and, as pointed out, it doesn't work with a piggyback camera.
You can use a guide camera/ OAG to get long exposure images.
I used one for a while with my spectroscope.
Mark,
What modifications do you mean on the derotator?? Mine work straight from the box.

[marki]

I remember reading something a long while ago about a guy who had replaced all the bearings and had done extra machining etc to make it work properly. I had no luck when I tried one but I may have got a dud:shrug:. The folks at Bintel said get a wedge and I have not looked back except for the wobbly forks (LX200's don't like being mounted on a wedge with the forks hanging out in the breeze) but then there is always compromise. Have you tried any 15 - 20 minute subs with yours?

Mark

[BlackWidow]

It seems that the De-Rotator has got a bad wrap mostly from people that have never used or even seen one. It's a little like the story of opals being bad luck (fed by the Gold merchants in the UK). We I own one and have had problems with a faulty one. I was supprised that when I needed assistance all I got was to be told I should have got a wedge. However all of those people I had spoken to had never even seen a De-Rotator. I have to agree that less complex operations leave less to go wrong. However the Mead De-Rotator does what it claims to do and is a great option for mobile setups, and for those that want to take simple shots without being the best on the block. Where I am located I am not able to see the pole to align so the De-Rotator is a good option. If I want to use a wedge I need to operate at another location. Just remember if you choose this option you WILL need a weight system to balance the scope or you will get poor results. I think overall a Wedge is a better system, and even better if you have a perm setup. I am going to build my own shortly (easy to do). However its very hard to build a De-Rotator so I purchsed one. Now I will have both options. I use a Web Cam through an AutoGuider as well. It can be a little difficult to find a guide star at times, but I can be set up to take pictures in as little as 15 mins..

My opinion is if you have the money to invest in a De-Rotator you should do it. It will get you results you will be happy with. Then add to the fun by making your own Wedge (plans on the net)., Then learn to polar align and extend your options.

Or buy some meat and beer, have a BBQ and look at pictures in a mag... Hmmm,,,, does sound good, but na, get the De-Rotator.


Cheers
Mardy :D

[GrampianStars]

:lol: You don't need to see the pole ever just line up the wedge N/S and a quick drift align your good to go in say 10 minutes :thumbsup:

[marki]

I have two questions for you Mardy.

1. Your exposure times with a meade de-rotator?
2. Have you tried align master..polar alignment in 2 minutes.

Mark

[Merlin66]

I'll let Mardy comment, but I was getting up to 20 min guiding with the QHY5/ OAG and the de-rotator.

Ken

[marki]

Ken the one I had used to catch and jerk messing up any attempt to get round stars. I am not into meade bashing, I own quite a few of their products. Like I said perhaps I just got a dud.

Mark

[bojan]

This discussion remind me of similar re an.. too much passion, too little reasoning.
The fact is (stressed very precisely by David Higgins): derotator is necessary evil.
It is useful when you do not have other choice, in cases such as big altaz telescopes.. but it is additional mechanical device, it is expensive (even to DIY, it is not straight forward to build), and if it can be avoided it, it should be avoided.

[BlackWidow]

In reply to bojan, I thought I gave several reasons for choosing a De-Rotator. Also as I mentioned I will also be using a Wedge. It's fair to say that if you want to go shopping you dont take the truck, but you may need a truck. I have also had a great deal of trouble finding a person that is able to assist me as I was learning, so a De-Rotator for me got me in the action fast. I found it far easyer to get results that I was happy with. My main point is also that a De-Rotator does do what is suggested. Exposure times of 15 - 20 mins with upgraded Peterson Gears. I don't think we will all ever get a diffinitive answer, but I an more than happy with mine.


:thumbsup: Mardy

[GrampianStars]

:eyepop: a solid wedge for $350 what a steal
http://www.iceinspace.com.au/forum/showthread.php?t=59272&highlight=wedge
absolute bargin for a wedge
beautiful work Hans :P

[bojan]

It doesn't have to be 350...
This is what I did some time ago, using Al L-profiles (60mm, to carry 2kg load).
As an idea..
Just extend the base bars and add additional reinforcement for those at angle to handle heavier scope.. and voila!
It does not have to have the fine alt adjustments (unless you are travelling a lot), this can be done on tripod or pier.
Couple of bucks total..

[chrisc]

Thanks for all the discussion and opinions, guys.

Sadly, I have now decided to just buy a (reasonably) decent equatorial mount with a goto system (SW HEQ-5-Pro), and toss a new OTA on top.

Still pondering which OTA... but that's another story. :-) It likely won't be an LX-200-ACF now, though.

Cheers,
Chris

[bojan]

No mate, this is a right decision :thumbsup:

[DavidTrap]

I was interested to hear where this thread went. Ultimately you made the same decision I did, to move from a fork mount to GEM! I should have talked to the experts first!

DT

[chrisc]

Now comes the dilemma of what to put on the mount (which will be arriving tomorrow)...

Umming and ahhhing between a fast short Newtonian for bright wide field photos, and an SCT for convenience, better mechanics (camera, etc., attached axially out the back rather than dangling at precarious angles creating unwanted levers).

Heavily leaning towards simply opting for both... an Astro-Tech 200mm f/4 Newtonian (~$650), and a Celestron C8 (~$1,100). Though I think I might go for the C8 in the first instance, with a FL reducer, and find out what I can't do it with it, before considering the fast Newtonian.

Chris

[bmitchell82]

Chris if you want you can always move the celestron to a Fastar setup, Marc, multiweb has done this with great results.only catch is to have a small camera :) That way you can interchange it between the best of both worlds....

The only thing is that youll be pushing the mounts capabilitys to hold such a large weight.

Another option could be a nice refractor? say 127ED that some of the members have purchased? look for something around the 700-900mm FL which will give you a decent FOV+ less hassles.?

if you have never taken a astrophoto before, then i would suggest a small fast refractor. no iffs or buts about it. youll learn how to take quality data, how to guide and process the quality data! instead of crying becaues 80% of your 30x 5 min subs are all up the duff! I have been at it for over a year now and juts starting to get the hang of it all. Check my website youll see what i mean :) go right back into the archives and youll find the pieces!