Hi All
Advise appreciated on the purchase of a new scope.
I currently use an Orion Eon 85mm Triplet EDX-2 refractor.
Focal length 561mm, f/6.6. FOV is about 82 X 108 arcmin.
Camera: ZWO ASI1600MC
Mount: Skywatcher EQ6-R
It has been a great scope, and I have learnt a lot.
Considerations in order:
I live 250m from the ocean.
Everything gets covered in corrosion and slimey muck.
I don't have an inclosed observatory.
So I don't think an exposed mirror is the way to go.
Portability and robustness:
I drive to a mountain site over rough dirt roads.
My old 12" Dob always needed colimating after the trip.
So I guess that might happen to all reflectors?
FOV:
I would like to go smaller by about a 1/2.
I am always cropping my images to death.
Cost:
Not really an issue...within limits of loosing my wife :-)
Example of what scope I have in mind:
SkyWatcher Esprit 150mm Super Apo OTA
Diameter 150mm
Focal Length 1050mm
F/7
I wonder if the 'Tak' guys might enter the debate?
Yes, sure. Go for it! Having owned an Esprit, I highly recommend them.
Accessories included are instant resale stuff (not overly fantastic), but then you put that towards better items like a Baader finder etc.
I have also seen images through one every bit as good as an AP or Tak.
Having also seen one in the flesh at Bintel, you will NOT be doing any favours for yourself with an EQ^ of any flavour - I'd be going EQ8 or something even better. The EQ6 is going to really dislike it for imaging.
Peter
I’ve used my 8” f5 newt and EQ6-R Mount for nearly 2 years now and my place is 250m from Narrawallee beach
I’ve had no issues with salt or mould etc... however I’m not at sea level , I’m up at 50m on a rise and have another hill in front of me with gums etc... so I guess I’ve got a little protection from the summer north easters
My scope is kept in the garage with a cloak over it , I’ve only had to clean the mirrors once in 2 years
I also have a 12” Goto dob for visual observing and again no issues with salt, mould etc... It’s also stored in the garage with a scope cloak over it
I really enjoy my imaging and visual rigs
Your location may be more exposed to the ocean and wind Etc..
Cheers
Martin
Regarding the EQ6 and the weight:
Suck it and see I suppose...
Regarding Takahashi scopes:
Some of the best images I have ever seen taken with them.
However I can guess that mostly, only the most experienced use them :-)
Regarding sea mist:
We actually get salt spray at times. You can see it in the air.
Conclusion:
I will go ahead and try the 150mm Esprit. Wahoo!!
I have an Esprit 150 and it is superb for imaging. It is heavy - 15 kg without cameras etc and very much front heavy with the stock focuser. I have a nitecrawler on the back end of mine and that balances it nicely but I am still at the very end of the dovetail in the saddle on the mount.
I run mine on an EQ8 but have an EQ6 as well and wouldn't try imaging with the Esprit 150 on the EQ6. I have used the Esprit 120 with the nitecrawler on it on the EQ6 and it copes well but the Esprit 150 is a much bigger scope and much heavier.
Skywatcher EQ6 mount:
It is rated for a 20kg payload, not including counterweights.
I have mounted a 21kg payload and it worked OK, sort of, up to a point.
Well come to think of it, I had a nightmare of a time.
But there where many other issues other than weight.
However, having said that, experience from Brian carrys a lot of weight :-)
I will factor in purchasing an EQ8 in the next phase if things don't work.
Takahashi TOA-150:
I have to say, it sort of scares me a bit.
As good as they are, it's like buying a $100k car (I drive an old VW combi).
Yes the TOA would have to be 2nd hand an even then it would be close to 50% more than the Esprit. Perhaps a TOA 130 may be a better comparison despite being smaller in aperture.
TOA optics from what I understand and have seen are the most perfect triplet optics available on any scope. But strangely I often see TOA scopes sold so owners don't always hold onto them. They are front heavy though I don't see that as a big issue, they may be (I don't know) temperature sensitive but perhaps they may go out of collimation more easily than other scopes. Either way you see them commonly for sale unlike AP scopes.
Another source to evaluate the Esprit would be the German optician Dr Rohr who posts rigorous tests on various scopes.
I must say I am impressed by the fact the Esprit is an airspaced triplet. They are rare. The TOA scopes are air spaced triplets but the 3rd element is a long way back not close together.
Most triplets are oil spaced as they are a lot easier to make as the optician only has to figure 2 faces rather than 6.
Just thought I'd chime in with some thoughts on the mount - I'm currently looking at a TOA130 which weighs about 12kg without accessories and was considering mounting it on my old EQ6-R.
I did some research and found a few threads on cloudynights basically saying that the EQ6 can handle visual pretty well up to 20kgs, but really struggles with imaging on anything more than 12-13kgs. Hence, I sold my EQ6 and am looking for a larger mount to take the TOA130.
If you are wanting to primarily image with this setup I would seriously consider a beefier mount. If you don't have a permanent setup and travel to a dark site, and cost isn't an issue then maybe consider the new AP Mach2 mount. It's costly (seriously, around $9k USD) but it's lightweight and can be traveled with easily, whilst also handling a decent load. The EQ8 is pretty damn heavy so might not be great for travel.
Portability and robustness:
I drive to a mountain site over rough dirt roads.
My old 12" Dob always needed colimating after the trip.
So I guess that might happen to all reflectors?
FWIW, I wouldn't totally discount reflectors unless there are specific reasons (spikes, too light, too cheap, too fast, too much aperture etc ) I'm in almost exactly the same position as you (a few 100m from the surf, observing and some imaging from mountain, and rough roads in between), and my refractors, whose advantages I appreciate a lot, rarely come out at home. It's reflectors nearly all of the time (when not using the small achros). An exposed mirror is no worse than an exposed front element. I don't really see how cleaning beachside muck off a 150mm refractor objective is any less daunting than washing a newt mirror in the sink, which is not daunting at all if one applies some common sense. Were I after 1m of focal length, I'd probably look at an 8" f/5 newtonian or even a 10" f/4.
Edit: Just saw the Wahoo! bit - congrats, it's a fine instrument nonetheless
I'd like to quickly say a couple of things. I've got an esprit 100. It's great in the centre, with excellent colour correction but I found it lacking in the corners for astrophotography on an APS-C sensor. The stars are very slightly elongated. This bugs me no end and I'm getting an FSQ106 for this reason. The esprits aren't as flat as they say. Pretty flat, but it was a slight disappointment for me.
Secondly... ED glass is relatively soft (not as much as true fluorite I'm told) and not corrosion resistant, or at least the multicoating isn't. Even a bit of inevitable bug juice marked up me front end glass slightly. I'm sure salt mist will also. It's not a biggie and doesn't affect the image at all. Just a cosmetic issue. But yes...if I lived 250m from an ocean I wouldn't get an open reflector either.
I'd like to quickly say a couple of things. I've got an esprit 100. It's great in the centre, with excellent colour correction but I found it lacking in the corners for astrophotography on an APS-C sensor. The stars are very slightly elongated. This bugs me no end and I'm getting an FSQ106 for this reason. The esprits aren't as flat as they say. Pretty flat, but it was a slight disappointment for me.
Secondly... ED glass is relatively soft (not as much as true fluorite I'm told) and not corrosion resistant, or at least the multicoating isn't. Even a bit of inevitable bug juice marked up me front end glass slightly. I'm sure salt mist will also. It's not a biggie and doesn't affect the image at all. Just a cosmetic issue. But yes...if I lived 250m from an ocean I wouldn't get an open reflector either.
I suspect you have something wrong with your flattener or sensor spacing then, because I use a Canon 6D (full frame) with my Esprit 100 and the stretchy stars are only barely visible in the last 100 or so pixels in the corner.
It's not for me to critique your purchasing power and choices, but I would say that an FSQ106 is a lot of coin and you might have been better served by asking why your Esprit was not working "as advertised"
I'd be very happy if I got an answer to this. It annoys me no end. I've tried a variable spacer between the supplied flattener and camera. Even after very careful manipulation of the distance, it seems to go from star trek warp speed distortion to circular distortion without going through pinpoint stars. Unfortunately it seems to be astigmatised, or an unfortunate hotchpotch of these two types of distortion. Could I PM you? You might end up saving me $10k with a few quick suggestions!
Sure! Thanks for helping. I got Bintel to change out the focuser to a feathertouch one so that I could use an autofocus. It's driving me insane!
Here's my new setup. If you could help me at all I'd be infinitely grateful. https://imgur.com/a/4WZiVpk
) I'm in almost exactly the same position as you (a few 100m from the surf, observing and some imaging from mountain, and rough roads in between), and my refractors, whose advantages I appreciate a lot, rarely come out at home. It's reflectors nearly all of the time (when not using the small achros). An exposed mirror is no worse than an exposed front element. I don't really see how cleaning beachside muck off a 150mm refractor objective is any less daunting than washing a newt mirror in the sink, which is not daunting at all if one applies some common sense. Were I after 1m of focal length, I'd probably look at an 8" f/5 newtonian or even a 10" f/4.
