16 replies to this topic

[astroflak88]

Hi All,

 

I just recently bought a C14HD and cancelled it on the same day after seeing some very nice pics from a member in here with his planetary pics using an XX16G (Dobsonian with Goto). This is not to say I'm not going to buy it anymore, just keeping options open. I remember a while back someone telling me or a post somewhere that the XX16G has bad tracking and insinuating that the images would come out bad but his images prove it wrong. Also the XX16G is over $1000 cheaper. I want to hear it from the experts in here the pros of one over the other if you were to drop that kind of cash. I am looking to order something this week.

Edited by astroflak88, 02 March 2021 - 03:34 AM.

[sg6]

Hi All,

<...snip...>

Would have expected the C14 to be better but in honesty have never had good results/experience visually or planetary imaging with an SCT. Rather fortunately I care little about imaging planets, look at them at times, not often.

 

Concerning the "very nice pics from a member in here with his planetary pics using an XX16G (Dobsonian with Goto)." Nobody posts the garbage images. All you will see are the ones that turn out good.

 

Did they have 20 failed images before the good one? That is what you need to know, not "Look at this good one." That good one means little. Does come down to being able to get a decent chance of a good image run everytime you go and set up.

 

Will ask my standard - why planets? We don't have many, 3 and a moon, and presently we really have 0 in any advantagous imaging position. Just in my mind comes down to having spent $$$ on a C14 or XX16G how many images of Jupiter, Saturn and Mars do you want?

[Supernova74]

I’m not an imager as I only do visual Astronomy,how ever I don,t think you can really compare the two as that are completely different breeds of scope.the dob is designed for large aperture,portable visual scope and I’ve seen amateurs use them with night vision assisted cameras with some very nice results,however thease devices are very exspensive.

you can go only so far in using a dobsonian scope for AP,imaging purposes as it’s on a azimuth mount after all,and I would believe it would introduce field curvature on long exsposure times on something like deep sky imaging,wouldn’t be able to track the objects effectively as no guiding could be achieved also.if your interests lay with planetary imaging of some discription yes it wouldn’t be impossible as you proved with the correct accessories and post processing software as long time exsposure times are not quite so demanding.

 

The C14HD is a high end premium imaging queen compared to the dobsonian and has been designed for that sole purpose also serious visual observing,the scope has edge optics which basically means flat images to the very edge of the FOV,mirror lock to maintain precise focus,dedicated focal reducers,overall a far superior optical,mechanical package.

there would be just no comparison when introduced to a high end equatorial mount,however to get there most probably cost you a least double the price to get you there that’s the trade of.

[astroflak88]

Would have expected the C14 to be better but in honesty have never had good results/experience visually or planetary imaging with an SCT.

<...snip...>

The images created with any of these instruments is not just 1 image. They take like 200 shots per second for like 3 minutes as an example, get the best photos out of the bunch and stack them on top of each other. Planets and moon are mainly what I want to image. I also image the sun using a refractor. And eventually will want to image deep sky like galaxies. I will create unlimited stacked photos of these objects like other members in here and astrobin.

[happylimpet]

If the C14 is equatorially mounted that will make everything a lot easier. A LOT easier.  In terms of pointing, tracking, and dealing with field rotation.

 

Of course a 16" will get slightly better resolution and more light than a 14", and a C14 has a larger central obstruction which slightly reduces contrast.

 

Im not sure which of the two will be easiest to get to thermal equilibrium. This is a massively important point.

 

This is not an easy decision.

 

I have an equatorially mounted 16" newtonian, and i certainly wouldnt swap it for a C14, but then that isnt the question!!!!

Edited by happylimpet, 02 March 2021 - 04:55 AM.

[CPellier]

Alt-azimuth Goto dobs are not limited anymore when it comes to planetary imaging (strictly speaking, not Moon), since WinJupos and Autostakkert will perfectly correct field rotation. The tracking is not as precise but you can fix that with PIPP. This is the only bad point, so think about it: you will have to correct the tracking by hand from time to time, and it will bring a limit to the frame rate, because you won't be able to crop the image during capturing as much as you would do with an equatorial mount. However the difference will be passing from 400 fps to "only" 300

Optics nowadays are good and it would be difficult to find a difference on optical axis. Dobsonians are Newtonians, so they will also deliver much better images in blue and UV!

The dob mirror is however closer to the ground, and so it could bring thermal issues if you don't observe on the grass.

I'm using a 305 mm Skywatcher Goto flextube since 2018 with excellent results, I have done everything from Venus UV to Saturn CH4 30 mn video imaging, getting details on Uranus and more.

So it's a deal between saving money, and spending a bit more time and complexity with the dob.

Look as well for the weight, if you have to manipulate the telescope often, you could find that annoying.

Finally, if you have already a good equatorial mount for the C14, this is also in favor of that last one. If not, the total price will be much higher than $1000 difference.

Edited by CPellier, 02 March 2021 - 05:19 AM.

[junomike]

Owned both, still have the xx16g.  Don't Image but If I did I'd go with the xx16g just on thermal properties alone.  The C24 takes a very long time to acclimate unless kept outside.

Loved both for Planetary, find the 16 just a bit better.

 

Also, you don't need the EdgeHD version of the C14 for Planets.  The standard will do the same fro less $$$$

[astroflak88]

Finally, if you have already a good equatorial mount for the C14, this is also in favor of that last one. If not, the total price will be much higher than $1000 difference.

I already have the losmandy G11 EQ mount with 2-22 lb, 1-11 lb counterweights.

This is the only bad point, so think about it: you will have to correct the tracking by hand from time to time, and it will bring a limit to the frame rate, because you won't be able to crop the image during capturing as much as you would do with an equatorial mount. However the difference will be passing from 400 fps to "only" 300

I have a technique for this at least when I had my skywatcher 150ed, I would pause the capturing and recenter the object on the center as close as possible and resume capturing. I will not capture while adjusting because you might accidentally capture the haze from the movement which could come out as a blur in the images.

Edited by astroflak88, 02 March 2021 - 09:41 AM.

[astroflak88]

Also, you don't need the EdgeHD version of the C14 for Planets. The standard will do the same fro less $$$$

One day I will eventually do deep space work so I'll just pay the extra $1k to buy the hd version. I'll go high right now on the models to avoid buyers remorse.

[astroflak88]

Dobsonians are Newtonians, so they will also deliver much better images in blue and UV!

This might be the deal breaker here for me because I will be imaging venus alot when she comes back out this year and I already have uvenus filter. I also have the power mate barlows all 3 of them (2x 4x 5x)

Edited by astroflak88, 02 March 2021 - 09:42 AM.

[gfstallin]

I have seen great work from Christophe (CPellier in this thread) and others with goto Dobsonians. There were some great images here and on Flickr from a man in Brazil who was manually tracking (!!!) his Dobsonian.

 

As others have mentioned, nothing is free. With that extra aperture for less money up front, you'll have some added complexity with tracking the planets and stacking images. I've always used equatorial mounts so I cannot speak to how this impacts the process/relative joy of imaging planets, but it doesn't seem to be the steepest of learning curves. Whether or not tracking and stacking work/complexity is worth the potential increase in resolution to you is another question. 

 

I too have considered going the Dobsonian route for increased aperture without additional expenditures on an equatorial mounting. My only hesitation was seeing the xx14g in person. It is only 3 inches tall in the brochure, but seeing it in person made me think of A Christmas Carol by Charles Dickens. The xx14g was the ghost of planetary imaging future, showing me using a walker for two years during physical therapy treatment. I'd save $5,000 on the mount, but spend $12K on back braces and learning to lift a 5-lbs. weight again. (Somewhat) joking aside, at first sight, I was relatively certain that it would live on a dolly in a shed if I am ever to use it, along with any issues that arise from that (stray grass clippings, insects, moisture). The base alone is wider than most of the doorways in my 100-year-old home.

 

Of course, the C14 is no petite waif either. The reason I haven't bought one and made it work on my CGX has everything to do with not having an observatory in which to use it. However, if I do change my mind about hauling a C14 from my house to the yard or I embark on a mostly steroids-based physical training/strengthening program, the C14 can fit through my doorways.  

 

George

Edited by gfstallin, 02 March 2021 - 12:39 PM.

[RedLionNJ]

I'd go with the xx16g. Aperture rules and thermal properties are a close second.

 

Of course, it depends somewhat on your local seeing - maybe you never get good enough seeing to make the most out of sixteen inches.

 

With reasonable tracking, modern tools like AutoStakkert and Winjupos can make maximum use of altaz-captured data.

[Tulloch]

Like Christophe, I do image the planets, I do it with an alt/az setup (the Celestron Evolution) but instead I use an SCT, not a Newtonian/Dob.

 

Small errors in tracking are not a problem, I usually usually need to nudge the mount every 10 seconds or so over a 3 to 5 minute capture to keep the target close to the center of the frame, but the capture software (FireCapture) will automatically adjust the capture Region Of Interest (ROI) 60 times per second to keep the planet in the middle of the frame.

 

If you want to get into DSO imaging in the future and already have an EQ mount that can hold the C14, then I would probably go that way.

 

I am considering upgrading to a 16" Dob myself, just got to find a spot to put it!

 

Andrew

Edited by Tulloch, 02 March 2021 - 05:36 PM.

[Kokatha man]

I'd suggest the C14 - stubby, less wind-affected etc for the same capacity mount, easy to thermally equalise & handle in general as well as collimate to a high degree. 

 

I have an SW 18" GoTo that I have adapted to the same EQ mount the C14 normally rides on but it is so large & bulky that it is rarely used. The 16" version is of course slightly smaller etc but apart from the cost angle would not hold a lot of attraction to me personally...& a secondhand C14 would bring its initial cost down...

 

As an example, which is a tad conceited  & where I normally just insert a link to our website (in the signature below btw ) here are a few images of the outer planets we've taken over the last 8 years: bear in mind that these are just (really) low-res screenshot jpegs because it's much easier for me to take s/shots off our website than searching for the actual images on my HD's..!  (you can see that from the file-sizes. )

 

Saturn was captured in this image 8 years ago with the earliest ZWO120MM camera...perhaps one of the best examples of this planet where clouds & storm spots spring out on the disk as well as a couple of moons, bearing in mind the excellent conditions that night.

 

The Uranus image goes back to 2014, our first year imaging this Ice Giant & records the large spot others also captured: no reliable captures of such a phenomenon have been seen since by any amateurs btw...

 

The rest with later model cameras: Neptune in 2015 where numerous BWC's (Bright White Complexes, storm spots) were picked up with one particular spot only imaged & confirmed by the HST which was imaging at around the same time...or as one professional commented <"our own images’ accuracies confirmed almost “point-by-point” in comparison to those of the HST">

 

Neptune again in 2017 where, despite the Keck team pronouncing "their" discovery of the (hitherto) unrecorded Equatorial storm spots, we had imaged them on 2 occasions before they did, something they later acknowledged because we had lodged our findings at the time with the BAA.

 

Jove is just a nice image from a couple of years back...as noted above there's plenty of other good images on our website.

 

EDIT - oops, also a couple of the Mars images from 2020 at under 50° elevation.   (again, cheap screenshots)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Edited by Kokatha man, 03 March 2021 - 04:32 AM.

[PiotrM]

easy to thermally equalise

This is highly region specific. In middle Europe my C14 with active cooling could be cooled to equilibrium but when imaging even after as little as 40 minutes air currents could show up in the OTA due to relatively steep ambient temperature drop.

[Kokatha man]

This is highly region specific. In middle Europe my C14 with active cooling could be cooled to equilibrium but when imaging even after as little as 40 minutes air currents could show up in the OTA due to relatively steep ambient temperature drop.

Piotr - the objective is to target the temperature you want over the duration of the imaging session: in Oz we can have temperatures in the 30C's during the late afternoon & drop to -5C* during the night or still sit around 30C all night...none of these temperatures are any real problem, although I suspect your notion of "active cooling" is vastly different to mine..!

 

Gradients here in the outback can be phenomenal at times btw! 

 

Peltier (TEC) cooling is simply not worth the effort from my perspective, having utilised it in a variety of additionally-sophisticated modes in earlier times.

 

Within the (more usual) temperature ranges I've just mentioned, we also find no issue with the C14 "tracking" the temp. gradient...for example the Neptune above where we started imaging at World's End (an apt name!) we were targeting Jove in early evening & the temperature would probably have been around 20-22C an hour or 2 before sunset (it is a warmish area in our Northern Mallee region) which is not far below what I read is the average July in Poland (summer)...for the June 13th Neptune image (winter here) it was roughly about 1.5 hours before sunrise & probably about 3-5C, with a wind chill factor making that seem much lower. (I know this because the web-page talks about a strong wind (southerly) being shielded by our caravan on the 14th July & the 10th June situation was somewhat similar...)

 

These "all-nighters" aren't part of our usual practise btw...

 

Granted it might get colder in Poland & we rarely experience snow in the regions we image from, but within a wide temperature gradient variation we experience no issues with most of our normal imaging sessions...I am confident that when we measure the primary temperature it really is a "core" value & perhaps this is assisting it to quite easily track the gradient when we chill it! (quite literally "chill" it which no peltier device would be capable of imho...)

 

* -3C & -4C are quite common, particular in mid-winter in Northern South Oz where daytime temps are in the low to mid 20's there...although the coldest we've experienced is only -6.5°C just north of World's End, where sheets of ice enveloped the ota & corrector & our former (non-SSD) laptop needed hair-drying to get the mech. drive HD to capture at the proper rate...discovering afterwards that the bearing lubricant used was not rated for operating at that temperature!

[astroflak88]

Thank you all for the feedback I'm learning new things from you all. After back and forth deliberation and second opinions and reading thru the forum and researching on google, I finally decided to get the c14hd.

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