Skywatcher Esprit 150mm APO

[AstroStudentUSQ (Mark)]

Anyone with first hand experience in using the Skywatcher Esprit 150mm APO? Am keen to hear about it's optical quality from those who have actually looked through it... Only interested in the optics. Cheers!

[Atmos (Colin)]

Although I haven’t seen one up close I’ve heard nothing but praise about their optics. Optically they hold their own up against the premium 6” refractors.

[PKay (Peter)]

This scope is also in my wishlist.

Does any one know how to calculate the FOV from the specs?
Mark should find this interesting as well.

For example, with my Orion EON:
Aperture 85 mm, focal length 560 mm, f-ratio 6.6
The FOV seen on the screen is about 3.4 X 2.6 degrees.

With the Skywatcher Esprit 150mm
Aperture 150 mm, focal length 1050 mm, f-ratio 7

What would be the FOV you end up with (aside from the answer...smaller)??

I suppose that the term 'field radius' might come into it as well??

More Info:
I just searched astrobin for Esprit 150mm.
The average field radius was 0.5 - 0.6 degrees.
And the images were 'superb'

[The Mekon (John Briggs)]

Check out this thread - it does not seem that many IIS members have these.


http://www.iceinspace.com.au/forum/s...d.php?t=151793

I ended up buying a CFF.

If you have changed your mind on the C14 you mentioned in another thread, then you are heading on the right track.

[Camelopardalis (Dunk)]

I know of two owners of Esprit 150 in the Brisbane area. Very happy by all accounts.

Unfortunately, I'm not one of them but I like my Esprit 100

[AstroStudentUSQ (Mark)]

Camelopardalis - is there any CA at all that you notice using your Esprit 100?
Are Skywatcher's marketing people being honest with their claims here?

Mekon - I was considering the Esprit 150 path but at $6999 (OTA) from Bintel, I think I would rather save a bit longer and for 3k more get a C14 EdgeHD OTA... At the end of the day, no matter how magnificent the refractor optics are, it can't get around basic physics: It is still only a 150mm aperture.

I'm going to go for an iOptron CEM60 Mount on the Tri-Pier (beautiful combo IMO!) Being 'centre balanced', it is lightweight but robust and 'works with' physics rather than starting from a position of inherent instability with the GEM design and then trying to make it work.

The mount also sounds freaking cool too - If you haven't heard it in action, you tube it - So cool!

The Edge14 OTA I belive is lighter than the equivalent meade, only 21kg. I lift 20kg weight plates around the gym all the time, I will just ramp up my military presses to practice lifting heavy things vertically haha (I used to be a personal trainer a few years ago part time to finance my first degree...)

If anyone hasn't heard of the iOptron CEM60 mounts and tri piers, check them out... I love them!

Mark

[Camelopardalis (Dunk)]

No CA from my Esprit or the 150 (I’ve seen mono and OSC images from it). This is not an unexpected result from a triplet apo.

[The Mekon (John Briggs)]

Mark, perhaps a bit of a reality check is in order. I other threads you post of photography intentions. I am no expert but a C14 on a CEM60 that may be a bit ambitious. The FL is 3900mm! You need a massive mount to deal with this FL! Time to come down to earth?

[Wavytone]

It's still only a 6" and nothing beats aperture or the simple laws of physics limiting its resolution.

It's an insane price as well considering say a 190mm Mak Newtonian will outgun this photographically on all scores for a third the price and similar focal length.

It's even more than I paid for my 9" Santel f/13 Maksutov.

[AstroStudentUSQ (Mark)]

Wavytone, I agree.

Mekon - at the native F/11 I would be doing only very short exposures and stacking them, for planets. I would later utilize the hyperstar configuration for imaging deep space at wide field F/2 thus making the set up a tad more forgiving. It would not be operating at 3900 fl for long exposures. The issue you raise is a non-issue, but I appreciate your thoughts, thank you.

Mark

[OzEclipse (Joe Cali)]

Originally Posted by PKay

This scope is also in my wishlist.

Does any one know how to calculate the FOV from the specs?
Mark should find this interesting as well.

For example, with my Orion EON:
Aperture 85 mm, focal length 560 mm, f-ratio 6.6
The FOV seen on the screen is about 3.4 X 2.6 degrees.

With the Skywatcher Esprit 150mm
Aperture 150 mm, focal length 1050 mm, f-ratio 7

What would be the FOV you end up with (aside from the answer...smaller)??

I suppose that the term 'field radius' might come into it as well??

More Info:
I just searched astrobin for Esprit 150mm.
The average field radius was 0.5 - 0.6 degrees.
And the images were 'superb'

Hi Peter,

The field of view is dependent upon the sensor size. You haven't told us what the camera sensor dimensions are.

You can calculate it for yourself : -

Field of view(degrees) = 57.3 x (sensor size)÷(Focal length)

Formula contains simplifications. This formula becomes progressively less & less accurate for focal lengths shorter than about 100mm.

Joe

[PKay (Peter)]

Hi Joe

Can we nick into a new thread, I don't want to hijack this one.

I will start it up 'FOV Calculations'.

Thanx

PK

[LewisM]

You need to ask yourself the question: do you really, really, really want to go down the iOptron path???

As a wise man once said "If we choose to walk into a forest where a tiger lives, we are taking a chance. If we swim in a river where crocodiles live, we are taking a chance. If we visit the desert or climb a mountain or enter a swamp where snakes have managed to survive, we are taking a chance. If we purchase iOptron and expect good results, customer support and mount longevity and precision, we are taking a failure route."

[Camelopardalis (Dunk)]

+1 I’d skip the fancy looking and stick with a mount that works, like an AZ-EQ6...

Plenty of capacity for most, it’d carry a C14 but I’d not put money on long exposures.

[LewisM]

Agreed Dunk. Hard to beat the AZEQ6 in its price range.

[AstroStudentUSQ (Mark)]

I have heard nothing but great things from iOptron customer support.

As for specs, see
https://www.ioptron.com/product-p/7201.htm

It is a very accurate and powerful mount.
"Precision stepper motor with 0.06 arcsec accuracy for precise GOTO and accurate tracking"

Many people do not quite understand the CEM concept and the comfort of their existing knowledge of GEM's gets the better of them. Don't be quick to dismiss what is an excellent innovation.

Regards,
Mark

[LewisM]

You'd better read Cloudy Nights mounts forum then. New thread of concern even today.

Best of luck if you go iOptron - you'll need it. There is a reason nearly every Australian dealer dropped iOptron (myastroshop, Sirius, Bintel etc)...you'll discover why...the hard way, if you buy iOptron. I have had iOptron - jitters, reverse slewing, no meridian flip and so on. Pure ****e. iOptron learns by subjecting consumers, then not offering any support for prior versions etc.

Looks mean very very little in mounts and telescopes. You want performance. Not a pretty design. I have heard a swath of issues with the CEM's and ZEQ's, not to mention the iEQ's. There is even an after-market supply of part that make the mounts work as they are supposed to (in NZ and USA, though I believe the USA guy gave up!). iOptron customer service never responds or answers the phone in the USA. I
d hate to know what it's like here!

You seem pretty sure of yourself for a newbie, so good luck to you. Listening to people experienced in these matters is a pretty important step in learning.

[The Mekon (John Briggs)]

Originally Posted by LewisM

You'd better read Cloudy Nights mounts forum then. New thread of concern even today.

You seem pretty sure of yourself for a newbie, so good luck to you. Listening to people experienced in these matters is a pretty important step in learning.

Well said Lewis. Mark as said earlier, you need to settle down a bit and not plunge in so deep. I notice on another thread you are asking comparison between Meade & Celestron paint finish!?

I wish you all the best in your studies, but there are many on this forum who have 50+ years interest in Astronomy and have learnt much over that time.

Tonight I am off to Goulburn to do an astronomy night for a school camp - this is the real fun part of the hobby, not equipment dreaming.

[DavidU (Dave)]

http://interferometrie.blogspot.com.au/

Half way down is a few optic tests.

[Atmos (Colin)]

The motors might have a step accuracy of 0.06” but that is not an indication of the mounts actual accuracy. So many other parts of the mount come into play when it comes to accuracy:
- Gears and worms smoothness and their exactness in size
- Strength of the machined parts, cheap mounts use casts as opposed to CNC machined
- Backlash
- Overall stiffness
- How well every comment fits together

It wasn’t until I upgraded from my EQ6 that I came to truly appreciate the awesomeness that is a premium mount. My counter weight shaft alone is of higher quality than my entire EQ6. It probably contains more metal than the tripod that came with the EQ6.

One could argue that I spent an obscene amount of money on a mount that in paper has virtually the same capacity and if you go by Sky Watchers marketing probably not that much better. Was it worth it? My god yes!

If I was doing imaging again on my EQ6 there is no way I’d put a 6” triplet refractor on it. Not on any cheaper mount with its capacity. It is not only heavy but has an incredibly long moment arm for a 6” telescope. For visual purposes yes but not for photography.

If you want to use the hyperstar at ~F/2 then it really depends on the camera you want to use as to how well the mount will handle it. It may have a 27kg capacity but I wouldn’t trust it with anything more than 20kg as an entire imaging setup. Once you go over the magic 75% capacity mark with some of the cheaper mounts it isn’t that you cannot do well, it just becomes more difficult to tame the beast.

As most will tell you, if this is going to be your very first astrophotography setup, don’t go in too hard too fast. The iOptron CEM60 may very well do you well (marketed as a slightly beefier EQ6) but I wouldn’t be throwing the biggest nastiest telescope on there as your first soirée.