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Advice on next telescope

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#1 IzztMeade

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Posted 24 May 2022 - 09:41 AM

I am really torn on my next telescope purchase so maybe you'll can help. I am loooking for a good complement to my 70mm Meade APO. I would like to reuse as much equipment as possible and I really like the idea of getting more galaxy shots (smaller targets). Searching astrobin the feeling I get with galaxies seems to be dominated by SCT/Newts/RCs however large APOs seem to hold their own unless person has really great seeing (could be wrong just feeling skewed). I think my seeing is ok to good FHWM seems to be low 2s" on average as I am a bit south of Denver with bortle 6 and 5800 ft in backyard but want to get into traveling a bit wiith scopes. I am still youngish so weight does not bother me yet.... Budget is < $5k out the door.. but don't want to over buy for my backyard conditions and current equipment.

Some of my shots so far:
https://www.astrobin...sers/IzztMeade/

Equipment:
ZWO ASI294MM
ZWO 8 position 31 mm EFW, optolong filters
ZWO EAF
ZWO ASI120MC - guide camera
CEM70
ASIAir Pro
OAG - looking to get with new telescope
flatterner - would like to purchase later if APC sensor already crops away

Top runners in no particular order

Astro-Tech 130mm - biggest concern here is I want the same or better optics of the 70mm meade not sure if this will deliver

Astro-Tech 152 mm - this may be off the table due to need of reaching temperatures in CO could be challenging, sales said has better glass as a secondary mating element over 130mm, but dang 152mm! Could be real nice visuually too.

ES 127mm $3k, can see more images on astrobin then the Astrotech for a little more get FCD100 glass, will be able to see at local store

Wliam Optics 132mm - FPL-32, seems a bit better built but 2x cost over astrotech, will be able to check it out at local store

TPO 10" f/4 Imaging Newtonian, wind sail, have to deal with collimation but I am not retired yet... so not sure I want to deal with that yet vs APO but if it gets me there much cheaper... maybe, cheapest option depending on accessories

Celestron 9.25" EdgeHD - collimation again and SCT related stuff, good on planets, $ getting up there with accessories , not sure when available

I have collected alot of comparison shots from astrobin but lets see boiled down a bit for needle galaxy

10" Newt
https://astrob.in/jtx54f/D/

ES 127mm
https://astrob.in/nmsm5x/0/

9.25
https://astrob.in/gmlyfj/0/

#2 c131frdave

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Posted 24 May 2022 - 10:23 AM

I have the GSO (TPO) 10" f4 Newt.  It's a fantastic telescope for the money.  It is very easy to collimate if you have a laser.  I bought a cheap laser off of Amazon and after collimating the laser (yes, you'll have to collimate the laser, but that's easy too), it takes me about 3 minutes to collimate the telescope.  The focuser is okay, but not fantastic for imaging.  With the money you will save from not buying a 6" APO, you can afford the best focuser in the world.  The biggest issue I have with it is the size of the thing.  It's big and heavy.  It laughs at the wind- it's 40 pounds, so it takes a lot of wind to move it while on a good mount.  On my CGX mount I've never really had any issues.

 

That brings me to the bigger question- what mount do you have?  That will probably have the biggest say in what telescope you buy.  Personally, if I had your budget, I'd look at one of those 10" carbon fiber truss RC telescopes and that nifty $500 laser collimation package on some ridiculous permanent mount.  I had a 10" RC back in the day, and I never did get it collimated perfectly.  But with today's expensive tools, I'd like to give it another go.


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#3 DRK73

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Posted 24 May 2022 - 10:39 AM

I'm in a similar boat except location - I live in a flat, humid, unlovely part of the country with worse light pollution, but everything else is kind of similar. smile.gif

 

I went down the Newt path, for better or for worse. Big refractors are nice, but very expensive and they get very heavy (though the WO 132mm is a nice scope). AstroTech is decent, but if you can afford to go WO or even Explore Scientific I think it's worth it - they are better made. If you're going to be imaging RGB with a refractor, it pays to get better glass. 

 

Anyway, as far as Newts go, I've made it my winter/spring (and probably into the summer) project to learn how to use them and run into challenges. 

 

I started out with an 8" f/4 and shelved it because I ran into a bunch of problems (reaching focus, vignetting, collimation, etc.). I decided I still wanted to get a Newt working so I stepped down a bit and found a 6" f/5 and have made some progress.

 

 

Here are some of the challenges I've run into using (especially) the faster Newts:

 

1. Yes, collimation is tricky and f/4 Newtonians are MUCH fussier than f/5 or slower. 

2. Your filters at f/4 may vignette - and badly - in an optical system that bright and that fast. I've imaged at f/4 in a small refractor and had no noticeable vignetting, but in the f/4 Newt it was bad enough that I was having to crop about 1/3 of my image area to remove. Turns out the light cone at the distance my filters are to my sensor is still WIDER than the 34 or so mm diameter in the filter wheel. Since I can't physically move the filters closer, I'm now upgrading to 2" filters for my asi2600mm. 

3. A recent conundrum I've found with Newtonians and my CEM70 is that the mount itself is where I want my camera to be. The counterweight assembly is in the way of where I'd put my camera so I've had to get very creative about placing my guidescope and additional counterweights so that my camera isn't running into the mount. This is with the 6" Newt, though - this may not be as much of a deal with a larger heavier mirror on a longer tube. 

4. Speaking of guidescopes, I tried an OAG with an asi290mm mini and wasn't getting any "improvement" - in fact, with the 290 if you're galaxy hunting you may only get one or two stars in the field - total - so multi-star guiding was going to be impossible. I'm now using an AT60ED as a guide scope and this clamps onto a Vixen rail I've got on the dorsal side of the Newt. 

5. Using an OAG with the asi174mm mini is probably better, but in another thread it was pointed out that the available sensor area with this camera is significantly larger than the image circle projected through the OAG, so you are not getting the full benefit of the sensor size - but what you do get is still larger than what you'd get with the asi290mm mini...

 

I've love an EdgeHD 9.25, too, and every now and then one comes up in the classifieds - and then disappears frown.gif

 

Good luck! 


Edited by DRK73, 24 May 2022 - 10:41 AM.


#4 DRK73

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Posted 24 May 2022 - 10:42 AM

I have the GSO (TPO) 10" f4 Newt.  It's a fantastic telescope for the money.  It is very easy to collimate if you have a laser.  I bought a cheap laser off of Amazon and after collimating the laser (yes, you'll have to collimate the laser, but that's easy too), it takes me about 3 minutes to collimate the telescope.  The focuser is okay, but not fantastic for imaging.  With the money you will save from not buying a 6" APO, you can afford the best focuser in the world.  The biggest issue I have with it is the size of the thing.  It's big and heavy.  It laughs at the wind- it's 40 pounds, so it takes a lot of wind to move it while on a good mount.  On my CGX mount I've never really had any issues.

 

That brings me to the bigger question- what mount do you have?  That will probably have the biggest say in what telescope you buy.  Personally, if I had your budget, I'd look at one of those 10" carbon fiber truss RC telescopes and that nifty $500 laser collimation package on some ridiculous permanent mount.  I had a 10" RC back in the day, and I never did get it collimated perfectly.  But with today's expensive tools, I'd like to give it another go.

He listed his mount: an iOptron CEM70. He's good there :)


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#5 DRK73

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Posted 24 May 2022 - 10:48 AM

One more thing to point out with Newtonians is that the focusers they come with are usually garbage. 

 

I bought my first second hand and it already had a Moonlite with a high res-stepper motor and all I had to get was the control unit. The Focuser itself is beautiful The control unit is something out of 1995. 

 

You will also need a coma corrector. 

 

I use a Paracorr 2 but this also acts as a "Barlow" multiplies your focal length by 1.15x so you need to keep that in mind and figure it into your image scale. My platesolve program (ASTAP) will fail if I don't account for the Paracorr effect.

 

There are other corrector options you can look around at. I suggest looking at the stuff for sale at TS Optics (in Germany but they will ship here). They have BEST collection of serious Newtonians and Newt accessories and can do custom work, as well. 



#6 IzztMeade

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Posted 24 May 2022 - 11:05 AM

DRK73, thanks for all the lessons learned / advice 👌. One part of me just wants a large reflector like telescope for the challenge / new learning lol while my more pragmatic part leans toward what I've used with the APOs.

#7 IzztMeade

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Posted 24 May 2022 - 11:14 AM

c131frdaven, RCs are tempting too, all the collimation woes worry me a bit... but someday wouldnt mind growing into spectroscopy and brightness measurements for the fun and learning which has some appeal with the RCs, not sure if that really matters much just was listed as a pro somewhere.

#8 drd715

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Posted 24 May 2022 - 11:59 AM

Look at the 140mm triplets. About as large of a refractor from a practical standpoint. 1 do use a 152mm, but the 140mm is easier to handle.  Or go for aperture, 9.25 or 11 inch sct.  Check out the Stellarview 140mm  - nice scope.



#9 bobzeq25

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Posted 24 May 2022 - 12:20 PM

I am really torn on my next telescope purchase so maybe you'll can help. I am loooking for a good complement to my 70mm Meade APO. I would like to reuse as much equipment as possible and I really like the idea of getting more galaxy shots (smaller targets). Searching astrobin the feeling I get with galaxies seems to be dominated by SCT/Newts/RCs however large APOs seem to hold their own unless person has really great seeing (could be wrong just feeling skewed). I think my seeing is ok to good FHWM seems to be low 2s" on average as I am a bit south of Denver with bortle 6 and 5800 ft in backyard but want to get into traveling a bit wiith scopes. I am still youngish so weight does not bother me yet.... Budget is < $5k out the door.. but don't want to over buy for my backyard conditions and current equipment.

Some of my shots so far:
https://www.astrobin...sers/IzztMeade/

Equipment:
ZWO ASI294MM
ZWO 8 position 31 mm EFW, optolong filters
ZWO EAF
ZWO ASI120MC - guide camera
CEM70
ASIAir Pro
OAG - looking to get with new telescope
flatterner - would like to purchase later if APC sensor already crops away

Top runners in no particular order

Astro-Tech 130mm - biggest concern here is I want the same or better optics of the 70mm meade not sure if this will deliver

Astro-Tech 152 mm - this may be off the table due to need of reaching temperatures in CO could be challenging, sales said has better glass as a secondary mating element over 130mm, but dang 152mm! Could be real nice visuually too.

ES 127mm $3k, can see more images on astrobin then the Astrotech for a little more get FCD100 glass, will be able to see at local store

Wliam Optics 132mm - FPL-32, seems a bit better built but 2x cost over astrotech, will be able to check it out at local store

TPO 10" f/4 Imaging Newtonian, wind sail, have to deal with collimation but I am not retired yet... so not sure I want to deal with that yet vs APO but if it gets me there much cheaper... maybe, cheapest option depending on accessories

Celestron 9.25" EdgeHD - collimation again and SCT related stuff, good on planets, $ getting up there with accessories , not sure when available

I have collected alot of comparison shots from astrobin but lets see boiled down a bit for needle galaxy

10" Newt
https://astrob.in/jtx54f/D/

ES 127mm
https://astrob.in/nmsm5x/0/

9.25
https://astrob.in/gmlyfj/0/

Of your listed choices, for DSOs, the WO 132 stands out.  Quality and ease of use.  A 2-3X Barlow turns it into a quite decent planetary scope, though the 9.25 SCT is better for that.  The 132 is good for lunar, also.

 

And, it's expensive of course.  Whether it's "worth it" is just a personal decision, not some universal right/wrong.  Other's opinions are of remarkably little value to you.


Edited by bobzeq25, 24 May 2022 - 12:25 PM.


#10 c131frdave

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Posted 24 May 2022 - 12:43 PM

The new Baader  MPCC III for fast newtonians is 1X.  It does not change the focal length of the telescope.  It is also finicky as heck.... back focus has to be perfectamundo.


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#11 IzztMeade

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Posted 24 May 2022 - 01:11 PM

Look at the 140mm triplets. About as large of a refractor from a practical standpoint. 1 do use a 152mm, but the 140mm is easier to handle. Or go for aperture, 9.25 or 11 inch sct. Check out the Stellarview 140mm - nice scope.



The only one at 140mm that I see in my current price range is the istar

https://starizona.co...tom-fcl-140-6-5

ES is close and I could always wait abit and save some more.

#12 drd715

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Posted 24 May 2022 - 02:19 PM

The only one at 140mm that I see in my current price range is the istar

https://starizona.co...tom-fcl-140-6-5

ES is close and I could always wait abit and save some more.

I bought an Istar 140mm triplet lens and am building the scope now. Unfortunately work keeps getting in the way and I am out of the USA  working until November. Will finish scope in December and test it before 2023. My tube and end bells are done.  Baffles and painting are all that's left.  My 1st triplet.   The APM152ED is working well, but it is long for the mount (CGEM-DX).  I  had an APM140ED which was good, but needed the 3.7 inch focuser instead of the 2.5 inch it had. Nose heavy with the 2.5.  It was good enough for the F-7 non reduced,  but a triplet would be better if reducing. 




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