Buying a new OTA HELP!

[04Stefan07]

Currently I have an Astrograph after coming from a MAK. I have only used it twice but quickly realised that an Astrograph isn't the scope for me.

All I want is an OTA that can be used for both visual and astrophotography. When I purchased the Astrograph I actually didn't realise that this type of design is purely just for astrophotography. It has a great sized aperture and focal length but is more designed for deep sky stuff and for people who only want to image.

This is what I need in an OTA:
- Ability to use it for both visual and astrophotography
- Be used for planetary/moon and deep sky imagery
- Be suitable for an HEQ5 Pro mount
- Can be used with an Orion 50mm Mini Guidescope
- Budget of no more than how much the Astrograph is worth ($500).

Any recommendations or advice would be appreciated.

Cheers,
Stefan.

[Atmos]

I'd say an 8" newt either F/4 or F/5. Great for visual because of the small secondary and astrophotography, will need a coma corrector for larger sensors though but you'll need a corrector for most telescopes anyway.

[raymo]

Got to agree with Colin, but I would go with the f/5, easier to focus, more
tolerant of miscollimation, falls within your budget, and an HEQ5 handles it o.k.
raymo

[04Stefan07]

I have been eyeing the ones mentioned below.

http://www.bintel.com.au/Telescopes/Reflector/Bintel-BT200-f/5-Imaging-OTA/988/productview.aspx

I would have thought it was pushing it for weight though?

[04Stefan07]

My thoughts.

- SCT/MAK (would love to go down this path but to get an OTA that has a decent aperture is way out of my budget!)
- Reflector (this seems to be the way to go by many people)
- Refractor (again like the SCT/MAK it becomes very expensive to get one with a good aperture but the optics are fantastic).

Still very undecided, need a bit more help and suggestions.

[glend]

If your going to be imaging then you have to work the imaging capacity of the HEQ5, which really is probably around 12kg max. The manufacturers listed capacity sometimes is broken down into suggested imaging and visual limits. The published figures for the HEQ5 at 15kg is the visual capacity.
The GSO (aka Bintel) 8" f5 weight is listed as 12.2kg. Once you add in the camera, a guide scope, adaptors, etc your going to push up the weight by probably another 1 kg for all of that. So it looks like the that scope will be a possible imaging match for the HEQ5 but keep the attachment/accessories weight down for best performance.

[04Stefan07]

Good point mate.

Would like to keep the weight down though so I don't need to compromise my accessories.

[04Stefan07]

Any suggestions on the below?

- Celestron Omni 150 OTA (150mm x 750mm Newtonian reflector)
- SkyWatcher Black Diamond 120/1000

[glend]

Aperture is king, I would not go smaller if you can get an 8" within the weight limit. Teleskop-Express reworks GSO 8" imaging newts in carbon fibre tubes. The ota weight is just over 7kg inclufing the rings. However, as with all things carbon fibre it is more expensive than locally sourced steel tube standard versions, like twice as much or more.

[04Stefan07]

That would be a nice tube to get but Carbon Fibre would be way too expensive!

[rmuhlack]

My suggestion would be a 5 inch or 6 inch f5 newtonian. This would keep you within both your price constraints and the weight limits of the HEQ5. These are two options, both with 2 inch focusers which would be mandatory for imaging:

5 inch skywatcher newt: http://myastroshop.com.au/products/details.asp?id=MAS-069A
6 inch skywatcher newt: http://myastroshop.com.au/products/details.asp?id=MAS-069A2

I have previously used a 5inch newt for DSLR imaging on a HEQ5, with very good results - see astrobin link here (http://www.astrobin.com/search/?q=rmuhlack%20130slt&search_type=0&camera_type=any&camera_type=0&camera_type=1&camera_type=2&camera_type=3&camera_type=4&camera_type=5&telescope_type=any&telescope_type=0&telescope_type=1&telescope_type=2&telescope_type=3&telescope_type=4&telescope_type=5&telescope_type=6&telescope_type=7&telescope_type=8&telescope_type=9&telescope_type=10&telescope_type=11&telescope_type=12&telescope_type=13&telescope_type=14&telescope_type=15&telescope_type=16&telescope_type=17&telescope_type=18&telescope_type=19&telescope_type=20&telescope_type=21&telescope_type=22&license=0&license=1&license=2&license=3&license=4&license=5&license=6&sort=-uploaded)

[04Stefan07]

Would you know how much these tubes weigh?

[raymo]

My Skywatcher 8" f/5 weighs in at 9.9kgs complete with tube rings, dovetail, 9x50mm finder, electric focuser, open end cover, and dewshield.
My HEQ5 happily carries that plus my 80mm achro and a DSLR with lens, and a 12.5mm illuminated reticle EP.
You can remove the dust cover on the rear end if you want, it weighs
300gr, half the weight of a DSLR.
I agree with Glen, why go with a 5 or 6" when the HEQ5 will carry the SW 8" plus accessories easily?
Hope this helped.
raymo

[04Stefan07]

Looks like a Newtonian design telescope is the way to go.

Out of curiosity with the refractors other than aperture are there any good points about them?

[rmuhlack]

Well Stefan has stated he wants to keep the weight down and have an OTA for less than $500. Anyway, I found a 5 inch f5 newt to be a perfect match for the HEQ5. The setup I used, with OTA, 2 x losmandy dovetail bars, guide lens & cam and cooled DSLR (all shown here (http://www.astrobin.com/113722/)) was about 10kg. Great FOV, a well matched image scale (ie focal length to pixel size) and reliable tracking.

For reference, the 150mm without finder or rings is 6 kg (see here (http://www.skywatcher.com/product.php?cat=11&id=50)) while the 130mm without finder or rings is 3.7kg (see here (http://www.skywatcher.com/product.php?cat=11&id=49))

[Tropo-Bob]

+1 for 150mm.
Keep it to something that the mount can handle with ease.

[raymo]

For the imaging I can go along with you Richard, but Stefan wants visual as well, and the 5 just can't compete with the 8, especially for resolution
when viewing the moon or planets.
I've had all the popular scope types, but am biased toward Newts and
Maks, so I will let the refractor buffs sing their praises for you.
raymo

[raymo]

The HEQ5 easily carries the 8" f/5 with all it's accessories Bob.
If you look around this forum and elsewhere, I think you'll find that this scope/mount combo is arguably the most popular budget level rig.
raymo

[04Stefan07]

Mhmm hard choice here!

The main feature I am after is to have a good visual experience but at the same time to pop a camera whether it is a CCD or DSLR and take a few photos of planets/moon/deep sky.

I have used all types of telescopes and they all have their advantages and disadvantages. I know one type will be better at imaging then visual and vice versa.

Still not sure...

[DarkArts]

Within the weight limits of an HEQ5/AZ-EQ5-GT, your choices are limited.

You want visual and DSO photography and planetary and to guide with a finderguider all on an HEQ5-class mount. That's tough. I think you'll have to compromise on something. My pick would be an 8-inch SCT. The SCT is an all-rounder. You might just be able to guide it (when you have a, say, 0.63 focal reducer fitted) with a finderguider, but I'd go for a camera with big pixels or binning or a better guide method.

You ought to be able to find a Celestron C8 second hand but it might be a tad over $500 ...e.g., 'casstony' recently sold a C8 OTA for under $800.

Here are a couple of packages including C8s (you might be able to convince the seller to split the package):
http://www.iceinspace.com.au/forum/showthread.php?t=141549
http://www.iceinspace.com.au/forum/showthread.php?t=141525

Or, if you're really, really strict about the budget, here's an ad for a C6, which will be well within your weight limit and easier to guide:
http://www.iceinspace.com.au/forum/showthread.php?t=140957

Hope that helps. :)

[04Stefan07]

An SCT would be nice but they are just a tad too expensive.

I thought the exact same thing. I want to do so much but I think I do need to compromise with something.

Definitely want both the visual and imaging. I used to have a 127 SLT which was a fantastic little OTA until I dropped it and disconnected the mirrors inside it :mad2:

I already have a DSLR and used to have a NexImage 5 which I just recently sold so if I can get my hands on a ZWO camera I might just use that as my camera.

[Tropo-Bob]

I am a little surprised, but trust your opinion. I briefly had an 8' F5 (with an oversized secondary) and it certainly strained the EQ5 mount that I put it on. My main problem with it though was I thought it was very ordinary for visual observing. Do U find yours satisfactory for visual, and is it also with an oversized secondary? A follow up question if I may to the astro-imagers, are the reflectors with the traditional sized secondary satisfactory (or far inferior) for imaging compared to the scopes with the oversized secondary mirrors?

[raymo]

Firstly Bob, were you talking about an EQ5 or an HEQ5? The HEQ5 has
a max payload about 40% more than the EQ5.
I bought the 8" OTA used, so have no idea whether it has an oversized
secondary. I may be wrong, but I think the f/5 was made with either vis or imaging in mind, but the f/4 was made primarily for imaging. Someone
else can probably answer your question better than me.
My f/5 is fine for vis, as good optically as my 10" f4.7 Dob.
Sorry for the slight diversion Stefan.
raymo

[glend]

Many of the 8 & 10" newts sold as imaging newts, like the GSO models sold by Andrews have secondaries sized to illuminate a camera sensor thus they are larger than visually optimised newts which only have to illuminate an EP spot and your pupil. They can be used visually by inserting an extension tube in the focuser to move the EP further away in the light cone to achieve focus. Thus these imaging newts are not as good from a contrast point of view when used visually (larger central obstruction). Newts optimised for visual use may exhibit vignetting of image sensors. There are scope like Mak-Newts which are good both visually and imaging wise, running a smaller secondary mounted directly on the corrector - thus no diffraction spikes and undetectable coma. However they are heavier than standard newts and cost more. The Skywatcher MN190 is a great example but can't be used on a HEQ5.
Most scopes are compromises in some way, especially at the budget end of the market.

[04Stefan07]

No stress.

Not really any closer to deciding.

[barx1963]

If it was me I would buy the best scope you can afford for what you want to do now. If that is imaging, get the best imaging scope you can, if visual go buy a dob. Attempting to do both is going to involve compromise and leave you unimpressed.

Malcolm

[04Stefan07]

Cheers Malcolm.

Yeah compromising can be difficult! I am sure the scopes mentioned below are better suited for imaging but surely they can be used for visual. They may not be a 10/10 for visual but a 7 or 8/10 for visual would be good enough!

[barx1963]

In that case an imaging newtonian can always have a simple dob mount built for it fairly cheaply. This avoids the main issue with newtonians on EQ mounts which is the dastardly positions the eyepiece ends up in. Of course as mentioned the imaging newts are fast (f4 or f5) so can be a bit coma affected. That said, I have built a dob using an f4 imaging mirror and it works fine, I just ignore the outer part of the field! The larger secondary means a bit of light loss and lower contrast. the issue then would be will a HEQ5 handle it once you put a guidescope, guidecamera and main camera on it?

Cheers

Malcolm

[raymo]

My SW 8" f/5 is fine for visual, which is what I used it for before taking up
digital imaging [not very successfully].
raymo

[04Stefan07]

Sure.

I know that I would like to avoid adding too much weight to the scope which will restrict me on adding accessories such as a guidescope.

The HEQ5 Pro looks like it can take around 13.5kg so a tube under 8kg would be ideal in my opinion, have some accessories then have a few kilograms left.

[04Stefan07]

I have composed a list of some scopes (just using Skywatcher as an example, I know other manufactures rebrand the same scopes).

- Skywatcher Black Diamond 120/1000 Refractor
- Skywatcher Black Diamond 150/750 Reflector
- Skywatcher Black Diamond 127/1500 MAK

Have experienced all 3 different design types.

I got to say my favourite is the MAK as what everyone says aperture is most important!

[04Stefan07]

Ok I have been eyeing off the 6" Newtonian. There is a Skywatcher one and heaps of GSO ones.

Anyone got any more tips??

[04Stefan07]

Am willing to stretch the budget to $700

[raymo]

I loved my SW 150 Mak, maybe you could find a used one within
your budget, bit slow for imaging though.
raymo

[rmuhlack]

Stefan - what was it about the RC6 that made you decide it wasn't the scope for you? (i'm just wondering what a 150 Mak Cas would offer that the RC didn't, as they are both slow scopes with long FL). I would think the RC6 would be preferable to a 150 Mak Cas if you wanted a scope for deep sky imaging, however i would expect the Mak Cas would excel at lunar and planetary visual/imaging.

[04Stefan07]

The RC6 is more for imaging plus it was very weight heavy at the back, more than the SCT I used to have.

Now that my budget is stretched a bit it should make choosing a bit easier.