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Proper mount for both 8" SCT and 11" SCT

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#1 Mantis707

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Posted 22 August 2012 - 10:09 PM

Hi there. First let me say how much I have been enjoying lurking here and reading all of the vast wisdom of the posters. What an amazing community here...My jaw dropped and I was unable to pry myself from these forums until my eyes literally HURT.

So a HUGE thank you to all of those who take the time to post helpful responses to everyone...I hope to be able to give back someday as well.

I am coming back to astrophotography after about 15 or more years.

I have been reading everything I can, to prepare to make some purchases.... here is my situation:

I have an old 8" meade SCT (LX3) with RA and DEC motors on the standard fork mount. What I am thinking of doing, is de-forking it and getting a dovetail to mount it on some type of GE mount, to use with the modern equipment (auto guiding, laptop, CCD/DSLR etc). The optics are wonderful and my OTA is in excellent shape...heck everything is...but I have now realized that the mount is outdated for AP work.

1) So, is using the older OTA with a dovetail on a new mount the most cost effective way of getting back in to AP..or should I consider selling the whole thing and putting the cash into a new OTA? I looked around a bit, and I don't see that it makes sense to sell, when I can use the OTA...but maybe I am missing something?

2) If indeed de-forking the meade and putting it onto a mount is the best way to go, which mount will ALSO be able to support a c-11 edge HD & CCD/autoguider or DSLR/autoguider? (Will the Atlas or Ioptron45 be enough? Are there other choices in the $1500-2000 range I should consuder?(

3) which dovetail plate would i need and how hard is it to defork the 8"?

I had thought (with regards to 2) that the Atlas EQG or the Ioptron45 would be the best bet for an AP mount for both scopes (separately of course), but I am not sure about the weight capacity....

I'd like to be able to buy a nice mount that I can use with my meade 8" for a bit and then save up some cash and eventually in a year or two buy the c-11 HD edge...

But I really don't want any problems when I do upgrade my OTA. From everything I have read it seems 11 inch is right on the verge of being too heavy for the Atlas EQG / Ioptron plus all the AP gear...

Any guidance on these 3 issues would be appreciated!

Thanks Gents,

Mantis

#2 Falcon-

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Posted 23 August 2012 - 12:24 AM

Welcome to Cloudy Nights and welcome back to AP! :grin:

1) So, is using the older OTA with a dovetail on a new mount the most cost effective way of getting back in to AP..or should I consider selling the whole thing and putting the cash into a new OTA? I looked around a bit, and I don't see that it makes sense to sell, when I can use the OTA...but maybe I am missing something?


I would agree a EQ mount and your de-forked OTA is a good way to do it.

2) If indeed de-forking the meade and putting it onto a mount is the best way to go, which mount will ALSO be able to support a c-11 edge HD & CCD/autoguider or DSLR/autoguider?
I had thought (with regards to 2) that the Atlas EQG or the Ioptron45 would be the best bet for an AP mount for both scopes (separately of course), but I am not sure about the weight capacity....


Hmm... the C11 is so much longer focal length and so much heavier that shooting for a C11 capability will certainly raise your cost higher for DSO imaging..... UNLESS you are intending to do Hyperstar mode and/or planetary imaging. (Hyperstar's short focal length and fast focal ratio lets you get away with a cheaper mount, and planetary imaging's exposures are short enough to likewise not care about long-exposures tracking/guiding)

Both the Atlas and iEQ45 would be excellent mounts for the 8" SCT, but my gut says not for the C11. Even a Losmandy G11 might be a bit light to drive the C11 at prime-focus for DSO imaging. I have only personally used smaller scopes and mounts so I will leave it to others on the forum here to recommend a C11 worthy mount.

3) which dovetail plate would i need and how hard is it to defork the 8"?


What plate depends on what mount you get - likely any mount that the C11 would ride on would use the Losmandy D type dovetail. There are several sources for dovetails for a de-forked SCT - I just recently de-forked an old C8 and used ADM's dovetail - very nice stuff ADM makes. Here are ADM's Losmandy (D type) and Vixen (V type) dovetails.

I'd like to be able to buy a nice mount that I can use with my meade 8" for a bit and then save up some cash and eventually in a year or two buy the c-11 HD edge...


I would like to ask... what type of targets to you plan to image with the C11 HD? It may be that you do not really need that large of a scope. With the small pixels on DSLRs and CCDs these days a shorter focal length scope with good optics can often do just as good a job as a big scope! You might in fact find that you want a smaller scope like the AT65EDQ for a wider field of view instead of a longer focal length when the time comes to get a second imaging scope....

#3 orlyandico

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Posted 23 August 2012 - 02:58 AM

I think a G11 on the HD tripod is the minimum to image with a C11. A reducer might drop the requirements enough that an Atlas could carry it, but I'm still not optimistic.

I have a CGEM (Celestron equivalent of the Atlas) and a C9.25 - and I wouldn't try imaging with the C9.25 on the CGEM. Unless I have the reducer on it.

#4 EFT

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Posted 23 August 2012 - 10:18 AM

1. Yes, using the old 8" is a good way to go. However, you may want to just sell that and buy one of the C8HD combos that are on sale right now.
2. In general, while not impossible, I would say that the Atlas class mount will not be a good way to go for the C11HD. However, there are people who I know (with the CGEM or Atlas) that do use a C11 on that level of mount.
3. Deforking is not that hard. Just realize that you need to disassemble the fork, not just slide the OTA out. I would always recommend using Losmandy or D Series dovetail plates for greater stability. The mount may need to be upgraded to handle that size dovetail though.

Getting a mount in the Atlas/CGEM/iEQ45 class is not a bad way to go for now and it is cost effective. Just realize that if you really feel the need to upgrade to the C11 down the line, you may also need to upgrade your mount.

#5 Mantis707

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Posted 23 August 2012 - 10:26 AM

Thanks you two for the responses!

Falcon- Your website is VERY cool...such an inspiration! Thank you for the ADM link. I am going to highly consider your advice on perhaps using a smaller scope....I mainly want to do galaxies, and planetary nebulae....but I also would like to do some wide field nebulae and so forth. I guess I will want at least two scopes....like an 8/9/11 inch sct / rc and maybe some kind of refractor or something with a shorter focal length...Thanks again for the advice.

Orly:

Thanks! I suppose I will have to increase my budget a bit if I want to have the option of AP with a C11 in the future. The Losmandy looks like a good option....but $3000 instead of $1500-2000.....Ouch! I was really hoping the CGEM, Atlas, Ioptron, LX80 or one of the under $2000 mounts could handle a c-11. I just want to have the option open of an upgrade to a larger scope in the future if ever wanted to....Like I would hate to spend 2000 on a mount that couldnt quite get the job done if there was one out there that could have.

Much Appreciated.

#6 Geo.

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Posted 23 August 2012 - 06:45 PM

If the LX3 has the silver coated secondary and it's still OK, you're lucky. Remove one fork's Dec axle knob, lay it on it's side with that fork down. Remove the other fork's Dec axle knob and the two allen head bolts retaining the fork to the base. Lift off the fork, set it aside and lift the tube off the lower fork. Remove the trunion plates and put them with the forks.

Generally, Celestron's 70mm wide dovetails are cheaper than Losmandy or ADM's. Won't fit the Meade 2080 through. So the DM8 is the best solution. If you sell the LX3 mount and wedge (I'd hang on to the tripod for now) the proceeds should cover the cost of the DM8. I just sold a pretty LX3 2080 (recoated secondary & V dovetail) for $460, so bear that in mind.

Thinking of parting with the C11 and 9.25 and getting an edge 9.25. So I guess I lean that way. Keep the CGEM. May sell the G11 as it now seems redundent to the CGEM, but it is much prettier.

#7 Mantis707

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Posted 23 August 2012 - 07:42 PM

George thanks for the tips!

I'm gonna de-fork it....How do I confirm that my secondary isn't one of the 'bad' ones? I can focus on stars, split doubles, and the optics seem good to me, but I haven't looked through any other telescopes in over 10 years.

#8 orlyandico

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Posted 23 August 2012 - 11:58 PM

IMHO one would use a C11 for high-resolution planetary or for visual.

If you want to do AP at long focal lengths for planetary nebulae or galaxies.. an AT6RC or C8 would be plenty. Save on needing a huge mount.

The Atlas class would work well with a C11 for planetary webcamming or for visual.

I really don't see the need to do DSO astrophotography with a C11... (I mean there is a need, but that would be for more advanced users, which I'm not)

#9 Stew57

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Posted 24 August 2012 - 07:42 AM

It all depends on the dso. Planetaries and many galaxies could use the increased image scale of the c11. Anything over 1200mm is really tough on man and machine!

#10 Bowmoreman

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Posted 24 August 2012 - 03:20 PM

If it were me, I'd go the *used* CGE route; handles the C11 for imaging just fine (been there, done that)...

then later add hyperstar

keeps the cost UNDER $2k, and with addition of the "Marty's cables" (from VPI for about $10 total), will work a treat.

#11 Mantis707

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Posted 24 August 2012 - 08:21 PM

Thanks Stew and Dave!

I will check out the CGE mounts. I was beginning to think I needed to get a G-11 or Vixen Atlux or Cge pro....or something along those lines.....WHich was going to mean a lower budget for other things at first.

I don't mind spending money on the mount, since it is the most important thing, and probably the thing that will last me the longest...but If I can get by with spending 2g instead of 4g on the mount, with little or no performance issues using a c11, then I would love to go that route..and use the extra money for things like focal reduction, etc.

Dave thanks for the tips on the cables!

#12 orlyandico

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Posted 24 August 2012 - 11:36 PM

Yup used CGE. Better if it has the Gary Bennett mods (which are an improvement over the Marty cables IIRC).

#13 adamsp123

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Posted 15 September 2012 - 09:55 AM

Thanks Stew and Dave!

I will check out the CGE mounts. I was beginning to think I needed to get a G-11 or Vixen Atlux or Cge pro....or something along those lines.....WHich was going to mean a lower budget for other things at first.

Dave thanks for the tips on the cables!


Just a word of advice regarding the Vixen Atlux....

I own a secondhand one and it is extremely well built and handles a heavy load with aplomb but......

The Vixen starbook when used for Astrophotography is a nightmare with horrible DEC jumps that ruin any attempts at AP but.......

I bought the NexAtlux replacement circuit control board and it has transformed the mount into a brilliant AP mount, will do 10-15 minute subs without a hiccup, I use Nexremote which is so easy to use on my command and control astro computer.

If you can get a secondhand one it is worthy of consideration IMO.

BTW it needs one counterweight, near the bottom of the CW bar to handle the 29lbs of SW 190 Mak Newt + camera etc.

HTH Pete

#14 Ed Wiley

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Posted 19 September 2012 - 10:33 PM

G-11. Have one and like it.
Ed

#15 Mantis707

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Posted 20 September 2012 - 05:57 PM

Thanks Orly., Adam and Ed..

Your council is much appreciated.

At this point I am back leaning towards the G-11 as I think it may be worth it in the long run to have a bit more stability for longer focal-lengths and heavier pay loads.

Thanks to all in this thread who took the time to chime in! I am all ears.

Mantis

#16 Aurneth

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Posted 22 September 2012 - 09:54 PM

How do I confirm that my secondary isn't one of the 'bad' ones?


That's pretty easy. Look at the secondary mirror from the exit tube at the back with the front lens cap off.

If the secondary is mottled with tarnishing, you've got a problem (that's the problem I have with my LX3). If you don't, then you don't have one of the silvered secondaries.


Note though that this is a coating issue. You could have a fully reflective secondary and it might still be 'bad' while a tarnished secondary could still be correctly figured.


As it happens, I'm planning on de-forking my LX3 for AP once I get it back as well, though I have to admit that setting up a fork mount for observational astronomy is a LOT quicker than setting up an EQ-6/Atlas mount. Just about everything involved in setting up an EQ-6 is a right royal PITA compared to Meade's fork-mounted LX3.

#17 rmollise

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Posted 23 September 2012 - 08:21 AM

IMHO one would use a C11 for high-resolution planetary or for visual.

If you want to do AP at long focal lengths for planetary nebulae or galaxies.. an AT6RC or C8 would be plenty. Save on needing a huge mount.

The Atlas class would work well with a C11 for planetary webcamming or for visual.


That's my opinion as well. Unless you are after smaller objects a good old C8 does just fine and is one heck of a lot easier to handle in every way.

#18 rmollise

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Posted 23 September 2012 - 08:24 AM


That's pretty easy. Look at the secondary mirror from the exit tube at the back with the front lens cap off.


Let me add that not all LX3s had silvered secondaries. It was available with standard coatings too, I recall. Anyhoo...ones that are vulnerable should be marked MCSOG or Multi Coated Silvered Optics Group...

#19 Geo.

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Posted 23 September 2012 - 02:16 PM

Let me add that not all LX3s had silvered secondaries. It was available with standard coatings too, I recall. Anyhoo...ones that are vulnerable should be marked MCSOG or Multi Coated Silvered Optics Group...


AND I've sent a few back into the world after a strip and recoat with aluminum. So have others. If it has the "Multi Coated Silvered Optics Group" placque look for some black spotting on the secondary's reflection in the primary.

Here's the worst I've ever seen and after an enhanced recoat that ran $30.

Attached Files



#20 Mantis707

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Posted 23 September 2012 - 08:57 PM

Truly you guys are awesome...thanks so much .I will most likely stick with my 8" for now, and the forseeable future....

I will probably end up with the Losmandy G-11, just in case i ever want a larger/heavier payload (i'm 39, and strong)or get more ambitious.

I have way too much to purchase before upgrading my 8" sct anyhow....

I am ordering a T4i and a mount....with all the fixings...So that eats up my budget for now!

I want to thank you all very much for the advice and tips....It is even cooler knowing if someone googles LX3 defork that this post might come up so you guys are helping countless people not just me...

Very kind of you all.

#21 Dan Finnerty

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Posted 23 September 2012 - 10:32 PM

You will really enjoy the G11. Your 8" CAT will be rock solid on it. It is a bit of a hoist, with counter-weights on, but I'm no longer a spring chicken and I can easily carry the tripod and mount with counter-weights out in two trips.

I presume you are planning on getting it with the Gemini 2 controller (based on the 3k price)? The software has finally matured and is working well. Join the Yahoo Losmandy and Gemini-2 discussion groups:
tech.groups.yahoo.com/group/Gemini-II/messages

If you have an ipad/ipod/iphone, get the skysafari software too when you can afford it. The skywire serial connector is relatively inexpensive. The more expensive skyfi wireless is wonderful. Skysafari is like having an astronomy book in your hand that points the telescope to the object you are reading up on. I've spent many happy evenings with SkySafari, my C11HD or 5" refractor and the G11 mount.

I've not ventured into astrophotography yet, but I've got the kit to do it when I'm ready. I know the G11/C11 combo will be a bit challenging at f/10, but I plan on starting with the refractor first, and also taking advantage of the f/2 hyperstar and .7x focal reducer on the C11.






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