Planetary / lunar rig

[Priesters]

Hi all,

Started Astronomy visually in 2018 and moved to imaging by about 2020 but now really fancy getting cold again out under the stars.   Looking to build a planetary/lunar rig with as quick a set up time as possible and also not using any of my existing imaging equipment (plan is to stay entertained whilst imaging).  So far I’ve come up with :

SkyWatcher AZ4 mount 

Skywatcher EvoStar 120 OTA

Don’t want to go beyond £700.

Just wanted to (be lazy and) check if there were any better options for quick set up planetary/lunar for a similar price?

Thanks

Andrew

Edited October 29, 2023 by Priesters

[RobertI]

I’ve not tried the Evostar 120 but I’m guessing an F5 achro will show a fair amount of chromatic aberration, which may or may not bother you. An alternative scope which springs to mind is the Altair Astro 102ED Starwave Ascent, which has an ED element (FPL51?), so should have less chromatic aberration, and is within your price range, but you will need to get a finder and diagonal. The FPL53 version is highly regarded so the build and image quality should be excellent. I’d agree with the AZ4 as a mount for that sized refractor, very happy with mine. 

[bosun21]

I would go for a 127 Maksutov on a basic EQ5 mount which both together come in on budget. I would choose the Bresser 127. Much easier to manage than the Evostar. It's also got an additional 500-800mm focal length which is ideal for planetary/lunar. If you want a quick set up you could replace the EQ5 for an AZ4. The Maksutov will provide crisp views without the CA.

Edited October 30, 2023 by bosun21

[Mr Spock]

8 hours ago, RobertI said:

I’ve not tried the Evostar 120 but I’m guessing an F5 achro will show a fair amount of chromatic aberration,

The Evostar 120 is f8.3  I have the old Helios version and it's a fine scope. There is CA but you can ignore it - a decent filter can help with that.

[mikeDnight]

11 hours ago, Priesters said:

Hi all,

Started Astronomy visually in 2018 and moved to imaging by about 2020 but now really fancy getting cold again out under the stars.   Looking to build a planetary/lunar rig with as quick a set up time as possible and also not using any of my existing imaging equipment (plan is to stay entertained whilst imaging).  So far I’ve come up with :

SkyWatcher AZ4 mount 

Skywatcher EvoStar 120 OTA

Don’t want to go beyond £700.

Just wanted to (be lazy and) check if there were any better options for quick set up planetary/lunar for a similar price?

Thanks

Andrew

Go for an ED if you can, even if it means dropping in aperture. If you can get a 120ED for under £700 then grab it and run. The cool down time is minutes and it will wow you not only on the Moon and planets, but also on brighter deep sky too. Something along the lines of a Starfield 102ED would also deliver beautiful views of the Moon & planets, and brighter deep sky. And the AZ4 is a greatly under rated mount in my view. I used an AZ4 with my FC100DC back in 2016 to observe Mars when the planet was so low it barely rose above the roof tops. 300X was no trouble when the mount was clutched gently. Pretty solid too!

Edited October 30, 2023 by mikeDnight

[Elp]

If you want more detail on the planets an SCT or equivalent would be the way to go.

[John]

The SCT and Mak-Cassegrain suggestions are great but they do need some cool down time to give their best planetary / lunar performance. The OP specified "as quick a setup time as possible" in the original post. That seems to point towards a refractor to my mind 🤔

If it was me I would be looking around at an ED doublet 100mm / 102mm F/7-ish that would fit within my overall budget. It will probably need to be purchased used though.

 

 

[Peter Drew]

So, are all the people who claim that insulating the OTA of a Mak/SCT avoids cool down time wrong?     🤔

[Mr Spock]

4 minutes ago, Peter Drew said:

So, are all the people who claim that insulating the OTA of a Mak/SCT avoids cool down time wrong?

How does that eliminate cool down time? All it does is stop the tube losing heat, which is fine once the scope has cooled; it still need to be at outside ambient temperature to operate at its best.

[bosun21]

I’ve just noticed that the OP specified a quick set up. With this in mind a refractor will be the best choice with a short cool down. I also agree that a second hand 100-102ED would be my preference. I have owned a 127 Maksutov and now have a 150mm which I have to give a minimum of 1 - 1 1/2 hour cooldown time.

[Priesters]

Thanks all - really appreciate the input and lots to think about.  As a couple of you have picked up on I’m looking for speed and simplicity with this rig so AltAz Mount is my preference but still undecided on the optics. That said having just splashed out a bit on my imaging rig I’ll need some time before I can get any further Astro purchases past the CFO.  Will update this thread when I do pull the trigger on a lunar/planetary rig.  Thanks again.

[Elp]

I've never specifically left a scope outside to cool down, it cools down whilst I'm setting up usually within 30 mins. Never had a problem with the C6. I'd understand if it were say a 925 or C11+ taken out from a warm house.

Edited October 30, 2023 by Elp

[John]

56 minutes ago, Elp said:

I've never specifically left a scope outside to cool down, it cools down whilst I'm setting up usually within 30 mins. Never had a problem with the C6. I'd understand if it were say a 925 or C11+ taken out from a warm house.

My 100mm refractor takes zero minutes to cool down. I can lift it out of the house and be observing at 200x plus immediately. 5-10 minute sessions (which on some nights are all that is available) are practical. If I did not have such a setup, I may well have got practically no observing in over the past 6 months 🙄

I have owned a number of SCT's from 5 to 8 inches and mak-cassegrains from 3.5 to 7 inches over the years and they were very good indeed, when properly cooled and dew protected.

 

 

 

[The Lapwing]

AZ4 mounts are excellent inexpensive and unrated for reasons which escape me. The steel legged on is rock solid with a 4 inch fl7 refractor which is the turn out I would buy in your position. A fpl 51 4 inch refractor and an AZ4 is perfect for you price bracket and could last a lifetime 

[The Lapwing]

16 minutes ago, John said:

My 100mm refractor takes zero minutes to cool down. I can lift it out of the house and be observing at 200x plus immediately. 5-10 minute sessions (which on some nights are all that is available) are practical. If I did not have such a setup, I may well have got practically no observing in over the past 6 months 🙄

I have owned a number of SCT's from 5 to 8 inches and mak-cassegrains from 3.5 to 7 inches over the years and they were very good indeed, when properly cooled and dew protected.

 

 

 

Like he said…☝️

[dweller25]

@Priesters

I know you said £700 max but…….

The AZ4 plus Starfield 100mm F/7 APO is a great combo.

The AZ4 plus Skywatcher 150mm F/12 Maksutov is also a great combo but you would need to wrap the scope with reflectix to ensure thermal equilibrium straight out of the door.

And finally, the good old 8” F/6 Dobsonian - enough aperture to show a lot of detail on the planets and well within your budget.

Edited October 30, 2023 by dweller25

[Clarkey]

Just to add another possible option - what about a 6" classical cassegrain? More aperture and FL than a refractor, but quicker cool down than a SCT or Mak.

[Peter Drew]

2 hours ago, Mr Spock said:

How does that eliminate cool down time? All it does is stop the tube losing heat, which is fine once the scope has cooled; it still need to be at outside ambient temperature to operate at its best.

Disclaimer.  I have yet to try out this approach to thermal management but my understanding (?) is that insulating the tube adequately SLOWS the change of temperature to the point where there is little optical distortion.  This, apparently, is n opposite effect to the thermal shock imposed by taking an uninsulated telescope from a warm house environment to an outside much colder one.  There are several claims to this effect on CN, some from very credible posters.

I have not tried this procedure as all our regularly used telescopes have their own unheated housings and presumably close to ambient.    🙂  

[Mr Spock]

I used to have an OMC-140 which I mistakenly kept in the house. Once I realised the issue with cooldown I kept it in an unheated porch and it was much better. Wrapping it did nothing as it doesn't solve tube currents - it only slows the rate of heat exchange. Only when it had properly cooled did it perform. The only other issue is when the temperature is dropping quickly outside the scope never cools quick enough. Maks are great if you can get them cold quickly. I store my Newts in a shed now and they are ready immediately.

I prefer refractors these days for small sizes as they are good to go from inside to outside very quickly - less than 20 minutes for the Tak from 22° to 0° 

[The Lapwing]

Look here: https://www.astrobuysell.com/uk/propview.php?view=206234

a bargain…

[Priesters]

1 hour ago, The Lapwing said:

a bargain…

OMG - the seller is actually located along my commute route to work.  I may just need to find a safe place to hide it from the CFO for a few months 😂.  

[The Lapwing]

13 minutes ago, Priesters said:

OMG - the seller is actually located along my commute route to work.  I may just need to find a safe place to hide it from the CFO for a few months 😂.  

That’s what car boots are for.
 

Obviously meant to be. Another 200 quid gets you an AZ4 delivered 

Edited October 30, 2023 by The Lapwing

[Priesters]

Ok, so after receiving some great advice I’ve changed the goalposts somewhat.  I remembered that when I started out visual I most enjoyed good close ups of the moon and planets so I’m going to need more focal length than a 4” refractor.  Plan is to start storing my Meade 8” LX200 ACF in the unheated summerhouse and buy a SkyTee to mount it on.  Hopefully that gives me a quick set up.   Obviously this puts the Meade out of simultaneous imaging action but I’ll still be able to use my WO GT81 for imaging.  I also think I’ll be able to use the redundant tripod from my EQ6 to put the SkyTee on (have a pier now).  Couple of questions:

- any obvious flaws in the plan?

- what magnification is realistic in average seeing conditions for an 8” SCT (2000mm FL)?

Thanks (and promise I won’t change the goal posts again 🙄).

Andrew

Edited November 4, 2023 by Priesters

[RobertI]

I think it’s a sensible plan to use the 8” SCT you already have - it should provide good lunar and planetary views. Personally I don’t go above 200x with mine, mainly due to seeing, so I wouldn’t say its longer focal length would be an advantage over a 4” ED refractor, but it should show slightly more detail on those really good nights and also more colour on the planets. I do like the sharp and contrasty views of my refractor, but you have your 80mm for that. 🙂

Edited November 4, 2023 by RobertI

[WestCoastCannuck]

Just to pitch my two cents in....   your original idea of the Evostar 120  (F7.5 FPL 53 Doublet)  is the way to go in my humble opinion.   The views are fantastic.   Inky black sky and sharp contrasty moon.  Heaven.  I am 90% lunar ......  and a bit of planetary.   Huge lunar imaging fan.   I started with a 100ED (FPL f53 doublet)...  and an 8 inch SCT.    LOVED the 100.   Not so much the 8 SCT....  had cooling and dew issues,  then there is collimation.  The 100 just worked.   Loved it so much,  I very quickly moved up to the 120 ED.  (Same FPL53 F7.5 doublet as the Evostar).    It was a HUGE step up from the 100.   The 100 views were super nice......  but the 120 could see so much more.   Yes....  its only a bit under 5 inches,  but really,  what a lovely scope on the moon and planets.  Around this time,  I also bought a 7 inch MAK and sold the C8.   I still preferred the view on the 120....  the MAK took quite some time to cool down,  and still the dew issues.   Also great mosaics and images with the 120.    The ONLY reason I don't have that scope any more is because of aperture fever - I moved up to the 140/7 APM doublet when the only one I have seen used in Canada came up,  and so I shall always remain -  I simply can't afford larger (or be able to mount larger).     I have a CPC1100 now as well......  and while I enjoy imaging with it on the moon (in my light polluted neighborhood) for visual I normally use my grab and go 102ED and when not imaging my 140.   Nice little scope the 102,  but pales in comparison to the 120/F7.5.    I DID finally find a mirrored scope I like to view planets and the moon with though....  a 150MAK.     It came with some other gear I bought,  and was very pleasantly surprised at the views.....  closest thing to a refractor I have seen in a mirror yet.    I won't be keeping it,  as the 102 is more versatile and I already have a 5.5 inch scope,  but its pretty darn nice for size and weight.

I will just add one more note about two of the scopes that I and others have mentioned,  since I have had both of them.   The 102 ED I have (FPL51) which is just one of the many many brands out there using the same glass,  is a great little all rounder and I love it .   The very little CA I see in it is not detracting for me.   But....  the 100ED on the other hand,  which is both FPL53  AND F9 rather than F7 is about the closest thing you will ever get to a true APO in a doublet. and better than the 102 on planets and the moon.   Just my opinion.... but there it is.  

 

Sorry to muddy the waters....

 

Clear skies

 

Mike

Edited November 5, 2023 by WestCoastCannuck
added note