Jump to content

Stargazers Lounge Uses Cookies

Like most websites, SGL uses cookies in order to deliver a secure, personalised service, to provide social media functions and to analyse our traffic. Continued use of SGL indicates your acceptance of our cookie policy.

sgl_imaging_challenge_banner_solar_25.thumb.jpg.f1d5d01d306644f613efd90ef96b314c.jpg

Hicks

Reached the limits of my mount?

Recommended Posts

Posted (edited)

I've had my 8" LX90 since 2002 and gradually moved from a visual interest to imaging, in particular galaxies. Not the ideal choice for imaging so it's certainly been a long road of (mostly enjoyable) pain to get images I'm happy with. However, I'm now starting to think with the low number of clear nights we get, I'm wasting precious time losing exposures to periodic error and guiding backlash by trying to get more out of this mount than I should rightfully expect.

My setup is the 8" LX90 (fork mounted) along with dew shield, heater, moonlite focuser, filter wheel, guider and ccd + assorted cables and counter weights. 1270 (with reducer) 1.04"/pixel. I've not checked the exact weight yet but hopefully that gives a rough idea of what I've got hanging off this.

Here's a not a-typical guiding snapshot from a session last year.

WS1_028.thumb.png.8103beb40dd9344379a8e8e8cc0c2ed9.png

The large spikes of around 4" are periodic error (sadly in the RA axis too). With a worm cycle of about 8.5minutes, that means on 3minute exposures I lose one in every three exposures. Even on nights when I've polar aligned sufficiently to be able to guide in RA only, I've found the RA tracking to require constant corrections. Whilst the LX90 does have PEC, it's not retained and since I setup fresh each session, it's time lost training that could be spent imaging.

I just get the feeling I may have reached the limits of my fork mount and doubt I'll be able to get that graph all that much smoother?

I don't feel it would be wise to invest time/money into trying to improve the mount in terms of gear upgrades. It would make more sense to defork and buy a new mount. I'd then have the added option of using a different OTA for wider field imaging. Also moving away from the fork mount, my imaging train would no longer impact the mount. I currently have a 25 degree or so no-go radius around polar north. tbh there's quite a long list of reasons why a new mount makes more sense than trying to improve my current one via upgrades.

However, that raises the inevitable question of which mount. What kind of improvement could I reasonably expect with a newer mount ranging from perhaps a lower end price point of £500-700 through to perhaps the £1500-2500 range. What would be the absolute minimum I should aim for given my current setup is 1.04"/pixel?

If I'm going to upgrade, I'd want this to be quite a significant step up from my current fork mount, what I'm not sure about is what price point that step up point begins.

Edited by Hicks

Share this post


Link to post
Share on other sites

I get the impression that even the best mounts require PA to about 5arcmins to be able to be effectively guided ?

That said a direct drive mount should relieve you of the chore of correcting PE.

I'm not sure about demounting then trying to sell the forks. 

Think about selling the LX90 complete and then look for a mount and ota ?

Or given your fork mount experience , buy a LX200GPS witn permanent PEC ?

Not sure the forks aren't  longer,  get closer to the polar regions ?

Michael 

Share this post


Link to post
Share on other sites

I'm not too concerned about selling the fork mount. In fact, I'd probably prefer to keep it in case I ever decided to switch OTA, then I could refork and sell as a complete package.

As far as mounts go, I'd prefer to move away from fork mount. Having the flexibility to use different OTA's on a mount is appealing (whether I do so or not) and my imaging train is rather long, I'd probably have to jump up to the larger LX200's to avoid issues and that's quite a cost/weight issue.

Share this post


Link to post
Share on other sites

8 inch SCT typically would be suggested a 40+ lb class mount.

So in that list would be things like eq6, az-eq6, cem60, cem40, etc etc.

iOptron does not work with guiding when PPEC is engaged. However, the don't really need it as their CEM series has PE spec and guides well enough to not really need the PEC. 

The eq6 and az-eq6 both can do PPEC and the PPEC upload is effortless with PEMPro vs the wait for it to take as guide inputs that ioptron has.

Beyond the ones above you can try the celestron models but I tend to think as lesser options.

Share this post


Link to post
Share on other sites
Posted (edited)

Agreed on weight capacity. I've been looking at mounts that cover the 50-60lb range.

Thanks for the info about PPEC, it sounds like the PE it does have is quite smooth and should be fine to guide out. The CEM60 is currently topping my list but I want to research it and several other mounts further before making any decision.

Edited by Hicks

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.