16 replies to this topic

[zakry3323]

Hey folks.

 

I'm looking at my observing logs from the last 3 years and I've come to the conclusion that I might be a lot better off observing with a different instrument. The great bulk of my observing sessions last less than 2 hours and I find that I've been using my binos or my wonderful but unwieldy 80mm F/15 refractor as my grab n' go on my Sky-Tee mount. 

 

What hasn't been getting much use is my 12.5" Discovery. On the occasion when the weather is extra nice, I'm very glad that I have it- it puts up incredible views. But I'm starting to wonder if maybe those views wouldn't be more appreciated by someone who will use it more often. So I'm thinking of putting it up in the classifieds, or putting an ad in the newsletter with the club. 

 

To replace it, I'm kind of stumped. I want a quick setup time, 6"- 8" of aperture, and a shorter focal length. It's rare, as in like 2 or 3 times a year when my skies permit magnification passed 150x, so I think I'll get a lot of enjoyment out of something that can produce a rich field. 

 

I've been looking at shorter Schmidt and Mak Newts. Looks like they're not nearly as popular as they once were, and that old Meade SN8's or a David Levy Comet Hunter (also discontinued) may be my only options. I've looked through both of them at star parties in the past and I thought they were pretty nice, plus no coma corrector to fiddle with. 

 

 

If you have any ideas I'd be happy to hear em. Yeah, I'd use my 8" dob but it's out on a long-term loan to a friend, as is my ED100. Just looking for something a bit shorter to stick on my Sky-Tee in any case, and wouldn't want to spend more than what I can get for my Discovery. 

 

 

[12BH7]

My gut feeling here is that your viewing taste leans towards bigger wider fields of view. 

 

It sounds like, from reading what you were viewing, that perhaps you should consider a refractor or a small Dob.

 

I know you have a refractor, but a f/15 is difficult to use. Go for a f/4 - f/6

Edited by 12BH7, 18 September 2024 - 11:47 AM.

[zakry3323]

My gut feeling here is that your viewing taste leans towards bigger wider fields of view. 

 

It sounds like, from reading what you were viewing, that perhaps you should consider a refractor or a small Dob.

Definitely, looking for wider views here. I've got my long refractor for splitting doubles

 

Big aperture fracs that I can use with my Skytee are not outside of my consideration, but to get even adequate color correction that means ED glass - maybe not outside of my budget for a 5" doublet if buying used or trading my Discovery. But they still tend to be pretty long, maybe not the best option for my mount. I get away with using it with my 80mm F/15 but if I get more aperture, focal length is going to have to come down to probably F/5 or F/6 to be manageable. 

 

No more dobs for me, I think, unless I move somewhere with very nice skies and I go big (and can keep it in an observatory and not have to move it). I'll keep my 8" F/6 at my buddy's house so I can use it with him when I visit.  

[sevenofnine]

Maybe a Celestron C6? Many members use a reducer and are happy with it. Good luck! 

 

https://www.celestro...y-cg-5-dovetail.

Edited by sevenofnine, 18 September 2024 - 04:31 PM.

[luxo II]

A Mak-newtonian is sharper than a Schmidt-newtonian, assuming both are good quality and properly collimated.

 

There are raytraces of both with spot diagrams on https://www.telescope-optics.net; off-axis the MN has a tighter image.

The other alternative is a Newtonian with coma-corrector. Whether that's preferable over a MN is up to you.

 

Forget the reducers with SCTs - while they produce a wider field they don't do much to reduce the FWHM of stars so you get a wide field full of embarrassingly fat stars compared to what refractors of the same focal length are producing.

 

You can see examples from my MN65 at the link in my sig.

 

The challenge is finding a fast Mak Newtonian.

Apart from the Skywatcher MN190 there are:

- a handful of Intes MN65's (165mm f/5);

- a handful of JMI/TEC 8" f/4 - rare as hens teeth;

- A few by Ceravolo.

- Vega made just 4 x 8" f/4.

- AstroMak 12" f/5... similarly small numbers, one on AM recently though optical quality is unknown and doubtful;

- very few (single digits) 10" and 12" MN's made by Intes and Intes Micro, around f/4-f/5, optically known to very good.

Edited by luxo II, 18 September 2024 - 08:06 PM.

[Echolight]

They're heavy for aperture and need a big mount.

I'd guess the SkyTee would be particularly rubbery with an SN8.

 

I'm sure this is why they aren't real popular.

 

Still, I've always admired the Comet Hunter.

Edited by Echolight, 18 September 2024 - 08:06 PM.

[luxo II]

Don't be ridiculous. The SkyTee is for baby refractors under 100mm.

 

An SN8 on a SkyTee would either tear the grub screws out (that alt axis isn't a solid one-piece affair if you look closely) or fall over sideways.

 

NB I have a SkyTee. I use it with a 70mm APO. 

Edited by luxo II, 18 September 2024 - 08:13 PM.

[Echolight]

A Mak-newtonian is sharper than a Schmidt-newtonian, assuming both are good quality and properly collimated.

 

There are raytraces of both with spot diagrams on https://www.telescope-optics.net; off-axis the MN has a tighter image.

The other alternative is a Newtonian with coma-corrector. Whether that's preferable over a MN is up to you.

 

Forget the reducers with SCTs - while they produce a wider field they don't do much to reduce the FWHM of stars so you get a wide field full of embarrassingly fat stars compared to what refractors of the same focal length are producing.

 

You can see examples from my MN65 at the link in my sig.

 

The challenge is finding a fast Mak Newtonian.

Apart from the Skywatcher MN190 there are:

- a handful of Intes MN65's (165mm f/5);

- a handful of JMI/TEC 8" f/4 - rare as hens teeth;

- A few by Ceravolo.

- Vega made just 4 x 8" f/4.

- AstroMak 12" f/5... similarly small numbers, one on AM recently though optical quality is unknown and doubtful;

- very few (single digits) 10" and 12" MN's made by Intes and Intes Micro, around f/4-f/5, optically known to very good.

For sure most of those would crush his SkyTee.

 

The Comet Hunter might work ok.

[12BH7]

I'd still look into a short tube 80mm - 101mm refractor. 

[jgraham]

I have both the SN8 and David Levy Comet Hunter. Personally, I prefer the larger SN8 for visual, but the Comet Hunter gives a better image across the field and is _much_ lighter. The stock Comet Hunter also has a better overall build quality than the stock SN8. My SNs have all been upgraded with Moonlite focusers.

Soooo, if you can work with a 6" scope the Comet Hunter is a nice option. If you want something larger and have an appropriate mount (I use an LXD75 for visual) the SN8 is a nice choice, particularly with an upgraded focuser.

Food for thought.

[dnrmilspec]

I have a 10" Schmidt Newtonian and it is a bit of a sleeper as a wide sky sweeper.  The corrector does an OK job but not perfect.  The stock focuser on these is marginal at best.  The views it puts out of big faint stuff however is very nice.  I keep threatening to sell it but at the last minute want to use it just "one more time". 

 

That said, I think the 8" SN will be too much for your Sky-Tee. 

 

I use my 9.25 and 8" SCTs with the reducer/corrector from time to time and enjoy the somewhat wider view.  An 8" Celestron SCT on your Sky-Tee may be a good choice.

[Freezout]

The comet hunter is available at Astroshhop in Europe.

 

https://www.astrosho...731-ota/p,22534

 

But it's on the heavy side and need a solid mount so you might end up with the same issue than with your dob (hassle to take out).

 

I have a Skytee 2, and cannot imagine it be qualified as "for baby refractor", it is widely used for bigger refractors or newtonians by satisfied owners as far as I know (especially with a counterweight). So I assume the Skytee you speak about is a different animal.

Edited by Freezout, 19 September 2024 - 03:49 AM.

[zakry3323]

I have a Skytee 2, and cannot imagine it be qualified as "for baby refractor", it is widely used for bigger refractors or newtonians by satisfied owners as far as I know (especially with a counterweight). So I assume the Skytee you speak about is a different animal.

I'm sorry- to clarify, I do indeed have a Skytee2. Once upon a time, for a laugh, I used it to dual-mount my Orion 8XT on rings and my SVX80 at the same time. Turns out that it worked quite well! I've had my Edge8 and ED100 on it with no issues, and using loooong slow-motion cables it's what I use regularly for my 80/F15 refractor. 

[Freezout]

I would feel comfortable to put the comet hunter on it...

[Jon Isaacs]

Don't be ridiculous. The SkyTee is for baby refractors under 100mm.

 

An SN8 on a SkyTee would either tear the grub screws out (that alt axis isn't a solid one-piece affair if you look closely) or fall over sideways.

 

NB I have a SkyTee. I use it with a 70mm APO. 

 

I have version of the Sky tee. It handles a 120 mm F/7.5 ED that weighs 15 lbs quite nicely. I've missed it at magnifications up to 720x though typically stayed under 500x.

 

The tripod matters..

 

 

I've used an 8 inch F/5 Newtonian on the mount as well as smaller Newt's. The problem is the ergonomics. You either have to reach around the scope to use the slow motion controls or the mount is between you and the scope.

 

Mak-Newt are slow to cool and heavy. Schmidt Newt's have crappy focusers are there are really no easy replacements.

 

A standard Newt with a Paracorr is an option. There was an 6 inch F/6 with a Mike Spooner mirror in the classifieds in the past few days. $400.

 

A C-6 or 5 inch APO might be a good choice.

 

Jon

Edited by Jon Isaacs, 19 September 2024 - 12:54 PM.

[zakry3323]

 

I have version of the Sky tee. It handles a 120 mm F/7.5 ED that weighs 15 lbs quite nicely. I've missed it at magnifications up to 720x though typically stayed under 500x.

 

The tripod matters..

 

 

 

I've used an 8 inch F/5 Newtonian on the mount as well as smaller Newt's. The problem is the ergonomics. You either have to reach around the scope to use the slow motion controls or the mount is between you and the scope.

 

Mak-Newt are slow to cool and heavy. Schmidt Newt's have crappy focusers are there are really no easy replacements.

 

A standard Newt with a Paracorr is an option. There was an 6 inch F/6 with a Mike Spooner mirror in the classifieds in the past few days. $400.

 

A C-6 or 5 inch APO might be a good choice.

 

Jon

 

Yours and mine look about the same Jon. Mine is mated to a Synta-standard  with 2" legs. I'll have to keep my eyes peeled, a 5" doublet might be right up my alley.

[Echolight]

I'd guess a 120 f7.5 doublet would be not too dissemilar from the 6" Comet Hunter.

....except the Comet Hunter would have a smaller eyepiece articulation.