Author Topic: Some help required LXD55 v's TAL 200k  (Read 4652 times)

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Rocket Pooch

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Some help required LXD55 v's TAL 200k
« on: Nov 11, 2003, 02:09:00 »
Hi,

Right I need some help, I’m going to choose between the following two telescopes as my new primary scope.

1 – Meade LXD55 8” (Schmit-Newtonian with UHTC coatings, 8”, F4 with 812mm focal length, .56 arc sec resolution) with all the Meade goodies.  This apparently is good optically but the mount is not very good.

2 – TAL 200k (Klevtsov Design, 8”, F10 with 2000mm focal length) on an EQ-5 mount with dual axes drives.  Apparently this is optically better than a Meade LX90 or LX200, but I’m not sure about the mount, the Meade type goodies I can live without.

Now the reason for joining the club was to ask the following types of stupid questions, so if you could help me with my decision would be great (I won’t hold it against anyone in the future, I might even buy you a pint for helping).  

My questions to you all are as follows: -

Has anyone used an EQ5 mount and are they ok, the tube assembly for the TAL weighs in at 12kg I believe this is within the limit of the EQ5.

If anyone has had an EQ5 was it ok for CCD work, and if so what exposure length was ok.  I understand from various sources the LXD Mead mount is ok for up to 20/30sec exposures.  Please note, I’m also thinking of attaching a SAC7 with a SLR lens to the mount for Wide Field imaging (especially after seeing Paul’s efforts).

I’m assuming the Newtonian type telescope should be better at deep sky objects due to the amount of light it can capture, does this sound right?

I’m assuming the TAL would be better for planetary imaging due to its focal length?

If you we’re spending £1,200 what would you get?  It’s not too late for me to change my mind.

Basically I’m after a telescope for both DeepSky and Planetary observing with some CCD work thrown in.  I’ve gone through all the Meade and TAL user groups on yahoo and apart from the TAL 2M (I’ve not discounted this yet but I’m not sure about the tracking capabilities of the mount) these telescopes seem to be about right for what I want to do.  

I’ve discounted similar spec Orion scopes due to their price, some of the other makes I’ve discounted due to their optical quality, but I’m still open to suggestions.

If you have any thoughts let me know what they are and please don’t sit on the fence be brutal it more fun.  

See you soon (hopefully with a new telescope).

Chris






Whitters

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Some help required LXD55 v's TAL 200k
« Reply #1 on: Nov 11, 2003, 06:01:00 »
Chris,

You have worked out the two basic ingredients you need. Decent optics and a sturdy mount. and then identified what you want to use the scope for.

1 Meade LXD55 8" (Schmit-Newtonian with UHTC coatings, 8", F4 with 812mm focal length, .56 arc sec resolution) with all the Meade goodies. This apparently is good optically but the mount is not very good.

Reply: f4 is very fast it means that you will require shorter exposure times to record the same object in a slower instrument. However there are trade-offs low f-ratio equates to less magnification at the prime focus, therefore a wider field of view. Which is just right for large extended deep sky objects, and glimpsing those faint galaxies. However f4 is very slow for planetary observation.

2 TAL 200k (Klevtsov Design, 8", F10 with 2000mm focal length) on an EQ-5 mount with dual axes drives. Apparently this is optically better than a Meade LX90 or LX200, but I'm not sure about the mount.
Reply: The f10 will give a greater magnification with the same eyepice, this is very good for planetary and luna work, it is also very good for the "less extended" objects like planetary nebulae, globular clusters many of the bright nebulae and galaxies.


My questions to you all are as follows: -

Has anyone used an EQ5 mount and are they ok, the tube assembly for the TAL weighs in at 12kg I believe this is within the limit of the EQ5.
I don't have any experience with the EQ5, my scope (16 years ago) origionaly came with a Super Polaris Vixen mount, it was good enough for the Celestron 8" though I did upgrade to a heaftyer mount three years ago, I had used it for photography and CCD imaging, but still use the SP mount for photography, it was the one I used at Headcord with the CCD and camera lens.
An excelent mount is unbeatable, an acceptable mount can be used successfully with care, a poor sloppy mount will drive you to tears.

If anyone has had an EQ5 was it ok for CCD work, and if so what exposure length was ok. I understand from various sources the LXD Mead mount is ok for up to 20/30sec exposures. Please note, I'm also thinking of attaching a SAC7 with a SLR lens to the mount for Wide Field imaging (especially after seeing Paul's efforts).

I'm assuming the Newtonian type telescope should be better at deep sky objects due to the amount of light it can capture, does this sound right?
Reply: The amount of light captured depends on the appeture and type of the instrument. ie if both reflectors then an 8" newtonian will capture the same amount of light as an 8" Schmitt Cass. Faster instruments require larger secondary mirrors and will affect the resolution. The best type is a refractor with no secondary an 8" scope will outperform a reflector. But to get a good one you have to pay the bucks.

I'm assuming the TAL would be better for planetary imaging due to its focal length?
Reply: Yes

If you we're spending £1,200 what would you get? It's not too late for me to change my mind.
All I can say is that I have heard very good reviews of the Orion instruments.

Basically I'm after a telescope for both DeepSky and Planetary observing with some CCD work thrown in. I've gone through all the Meade and TAL user groups on yahoo and apart from the TAL 2M (I've not discounted this yet but I'm not sure about the tracking capabilities of the mount) these telescopes seem to be about right for what I want to do.

Whitters

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Some help required LXD55 v's TAL 200k
« Reply #2 on: Nov 11, 2003, 07:16:00 »
Go-To can be very nice, but to start I would advise spending the Go-To money on the mount and optics, and a set of Uranometria. Nothing beats learning the sky and if you are imaging, then the thrill of seeing something like the horsehead nebula on your screen because you have worked out the starfield is a real thrill. I don't use Go-To I would not say never but there are other things I prefer to spend my cash on.

Rocket Pooch

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Some help required LXD55 v's TAL 200k
« Reply #3 on: Nov 11, 2003, 07:33:00 »
Thanks for the help and comments, it's been a lot better than any of the numerous shop owners I've talked to (with 1 exception, bit of a pub story that) and Yahoo groups I've visited over the past four weeks.  

I must admit I've been swinging towards the TAL because of the optical reviews and the focal length.  Also it apparently does not suffer from dewing.

I've kinda also assumed with .01 lux colour and .003 lux mono CCD's available the speed of the Meade would probably be less critical than it could be for planetary imaging and for wide field work the weight of a CCD system on the mount with an SLR lens should not be much of an issue the EQ5.  

I'll get you a beer at the next meeting.

If anyone else has any thoughts please let me know, I have some beer vouchers left.

Regards


Chris

Ian

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Some help required LXD55 v's TAL 200k
« Reply #4 on: Nov 12, 2003, 07:01:00 »
free beer? cool.

I have a eq5 mount, now sitting redundant in my shed together with dual drives. It is perfect for visual, pretty good for planetary photography but gets dire once the exposure times head over 20 seconds. It is fine for OTAs up to around 6kg in weight. I would say the Tal at 12kg would be way overweight for that mount. 12lbs you could get away with. Also bear in mind that the piggyback adaptors usually sit on the top of the OTA, opposite the mount and you may struggle to balance it.

My advice, buy the best OTA you can. My scope came from orion optics, and in my (limited and biased) opinion, they are the best company you could choose to deal with, considering their OTAs are some of the best in the business and their customer service is legendary. Provided I had money of all the other stuff like eyepieces, drives, cameras etc, then an Orion DX250 would do very nicely. Alternatively, buy an OTA from them, and make me an offer for my EQ5 and have a wad of cash to spend on other stuff.

I, like Paul, could probably go on all night. So next time we're in the pub, lets go through all the options.

Rocket Pooch

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Some help required LXD55 v's TAL 200k
« Reply #5 on: Nov 12, 2003, 21:45:00 »
Ok, maybe a longer chat after the next meeting is in order.  

Dam frustrating time I'm having picking a new telescope.  It does seem add about the EQ5, from what your saying the EQ5 seems completely pointless (mumble mumble).

Anyway thanks for the comments.


Ian

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Some help required LXD55 v's TAL 200k
« Reply #6 on: Nov 12, 2003, 21:54:00 »
frustrating? I think it's fun. Or am I being perverse?

To really work out which is best scope, you need to have a clear idea of budget, what you want to observe, where you will observe, what additional activities you may have planned for it (astrophotography, birdwatching, neighbours undressing etc.) Whether or not existing accessories will work with it, does you budget include accessories, or have you got a second pot for that (and don't think that you'll get by with the accessories you currently have, you'll be expanding your horizons (pardon the pun) and suddenly there'll be an unexpected sucking noise around the wallet area as you explore them).

Do you have any particular feelings around manufacturers to avoid or particularly want to deal with? Are you looking at buying in the UK or are you happy to import. Do you know which type of telescope you'll want (do you know the foibles of all of them so you know what you can and can't realistically do with them).

This is looking like it's about to turn into quite a session. Better get a cab to the next meeting :wink:

Rocket Pooch

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Some help required LXD55 v's TAL 200k
« Reply #7 on: Nov 12, 2003, 23:16:00 »
Cab? No chance it would cost to much from Mottingham and I'd be able to buy something else like another web cam to blow up.

I will let Karen know I'll be comming home after kicking out time at the next meeting.

But I do have a maximum budget £1,200.  I do want to have a good look at the planets, and if possible deep sky objects like star clusters and galaxies.

Also, I do like looking at the moon, but my ETX and my bino's are perfect for that.

The budget does excluse a proper CCD camera, SAC7 is the one I think I'll go for after I get the telescope and learn how to use it, unless I can fix the vesta (dam thing using a WeeCam now).

Yours confused

:sad:

Whitters

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Some help required LXD55 v's TAL 200k
« Reply #8 on: Nov 13, 2003, 03:50:00 »
Nice to see Ian finaly owned up to why he bought his scope :wink:

Whitters

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Some help required LXD55 v's TAL 200k
« Reply #9 on: Nov 13, 2003, 03:53:00 »
But seriously, I fully agree with Ian, go for the best optics you can afford, Other options are to check out the second hand ads in Astronomy now or maybe David Hinds or BCF websites. Though get a look at what you are buying before parting with cash.