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AstroStudentUSQ
28-09-2017, 02:12 AM
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
28-09-2017, 06:08 AM
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
28-09-2017, 06:36 AM
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
28-09-2017, 07:32 AM
Check out this thread - it does not seem that many IIS members have these.


http://www.iceinspace.com.au/forum/showthread.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
28-09-2017, 06:10 PM
I know of two owners of Esprit 150 in the Brisbane area. Very happy by all accounts.

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

AstroStudentUSQ
28-09-2017, 06:56 PM
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
28-09-2017, 07:00 PM
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
28-09-2017, 08:42 PM
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
28-09-2017, 08:50 PM
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
28-09-2017, 09:21 PM
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
28-09-2017, 09:26 PM
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
29-09-2017, 06:22 AM
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
29-09-2017, 07:09 AM
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
29-09-2017, 08:54 AM
+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
29-09-2017, 10:03 AM
Agreed Dunk. Hard to beat the AZEQ6 in its price range.

AstroStudentUSQ
29-09-2017, 02:38 PM
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
29-09-2017, 03:11 PM
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
29-09-2017, 03:36 PM
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
29-09-2017, 03:49 PM
http://interferometrie.blogspot.com.au/

Half way down is a few optic tests.

Atmos
29-09-2017, 05:53 PM
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.

LewisM
29-09-2017, 08:15 PM
Yup.



Yup, sums up Celestron and Meade SCT's very well :P :lol: :whistle:

RB
29-09-2017, 08:23 PM
LEWIS !!!
BEHAVE !!!

Tisk, Tak, Tak,

https://dl.dropboxusercontent.com/s/6wpleqtwamgpmgi/mad71.gif?dl=0

:lol:

LewisM
29-09-2017, 08:56 PM
Colin baited me... :whistle:

Logieberra
30-09-2017, 06:45 PM
+1. Well said.

Wavytone
30-09-2017, 08:38 PM
Mark just understand you will be on your own with an iOptron mount. If it is defective there is no support here and it will be all but trash.

AstroStudentUSQ
30-09-2017, 09:50 PM
Hey Guys,

Which manufacturer and subsequent dealer have you found to provide the best service broadly speaking? Myastroshop and Bintel are the two main ones I have been looking at (some others online are selling very old stock -
long discontinued telescope models for instance - even older than the LXD75 SN10AT I have (ps. the mount on this is ****. very shaky tube. It was my first "real" telescope, now I am looking for something better! I don't like the single bolt pushing against the dovetail plate versions. I will not buy any mount with that. I like the dual bolts that go through the mount, not against the dovetail plate, and when tightened a large clamp like structure encloses the dovetail plate - much more stable and safe securing the tube across an area rather than a single point!)

What are your thoughts on these mounts (they both have the attachment type I like...)

Skywatcher EQ8 Mount
https://www.bintel.com.au/product/skywatcher-eq8-mount/

Celestron CGX-L Mount
https://www.bintel.com.au/product/celestron-cgx-l-german-equatorial-mount/

Cheers,
Mark

Wavytone
01-10-2017, 08:28 PM
but everything depends on the choice of scope ... so what’s that going to be ?

Prickly
02-10-2017, 08:24 AM
Hi Mark

Had you thought about remounting your Schmidt newtonian on a mount like an Eq6. For planetary it might give a 6 inch refractor a run for its money. I've seen some quite nice deep sky images also on astrobin through the Meade Schmidt Newtonian.

Certainly the mak newt 190 is a great scope too and would come in cheaper than the refractor. It is hard to beat a 6 inch refractor though. The ED 120 also gets many good reviews. You would expect the triplets to be a step up again from this.

The Eq8 is a monster and I think really warrants an observatory. To me the tracking in images looks siuperb but it is very pricey. I find the Eq6 is a good size for lugging in the garden or field trips.

What year are you in your studies?

Cheers
David

AstroStudentUSQ
02-10-2017, 04:48 PM
Hey David,

I did consider remounting the SN but there are a few reasons preventing this...
The scope itself is in storage at a family's place in Adelaide, and I cannot find any business that ships highly delicate optical items from the mainland to Tasmania at a non-astronomical cost. (if anyone does know of such a business, please let me know!)
When I purchased the SN, Meade claimed in their specifications that the focuser was aluminium. They just plain lied in their specifications as the focuser unit is plastic. I would want to replace this for astroimaging but not only the focuser but the plate that connects the focuser to the aluminium tube is also plastic and would need to be replaced also. The only way to remove the this is to access the screws on the inside of the optical tube which means removing the corrector lens assembly fully, and this is something I do not wish to do! Should for any reason I not be able to remount the corrector lens properly, I have an unsalable scope! Also I am a more theoretical / abstract thinking type person and do not generally enjoy taking things apart. If I did, I'd be going down an engineering path rather than astrophysics haha.

Thanks for your advice re- Eq. 8. I had noticed the Maksutov Newtonian by (Skywatcher I think?) previously... The Schmidt and Maksutov newtonians are a rare breed but they do give nice wide field corrected views over the traditional newtonian.

I previously studied Geosciences with a BSc at Flinders (my interest in that being more directed towards Astrogeology. Recently I have been taking some single unit studies of a more quantitative nature in preparation for the BSc (Astronomical & Space Sciences) which I am enrolled in which USQ is commencing in the new year. I chose the new BSc (Astro & Space Sci) rather than other similar incarnations as I wish to take a meaningful amount of physics and mathematics with the astronomy and that can only be achieved within the BSc course structure.

After that I hope on going on into research degrees with UTAS (Greenhill Observatory there houses a 1.3m aperture research telescope!) I'm particulary interested in time domain studies of variable stars, stellar surface imaging with gravitational microlensing, and asteroid and TNO science with stellar occultations.)

Back to the recreational astronomy side, I have been reading about Meade's 'Starlock' technology with their LX600 series. They claim it automatically aligns the scope with the wide field camera it features, then with the second instrument, an 80mm F/5 refractor, hunts out a guide star whenever the telescope is pointed towards the sky, locks on and tracks with 1 arcsec accuracy - automating the entire process of both alignment and guiding. They claim this renders the need for guide cameras, off axis guiders, other software and laptops in the field etc archaic and irrelevant. I'd be keen to hear if anyone on this site has used this technology on that series of telescopes and put those claims to the test... I take what meade says with a pinch of salt.

David, which areas of recreational astronomy do you enjoy most? What are your favourite targets? What telescope do you currently have?

Cheers for your reply!

Enjoy your evening.
Mark

Prickly
04-10-2017, 08:42 PM
Hi Mark

Good to hear that we have a future expert on the forum. it will be interesting to hear about your projects. I think variable stars is a most interesting area in these days of ccds. Probably an area that amateurs can still provide a useful contribution too. My uncle who was ex-curator and deputy astronomer in charge at Mt Stromlo actually thought that was a good area some years ago. Gravitation microlensing is another really amazingly interesting area.

My interests are varied. I tinker around at home with little projects with fairly modest equipment. I have an achromatic petzval refractor (f5.7) and a 10inch f4 Newtonian. I have tried a little imaging with my unmodified dslr and filters and plan to do some narrowband on the eq6. I also quite enjoy looking a planets and am considering a binoviewer in the near future. Maybe one day a ZWO 1600 chip. I am not quite as patient or as into the imaging as many here on the forum. No 10 hour + shots I'm afraid (hence the 10inch f4 which I may try at f3.6 with the skywatcher 0.9 coma corrector). Don't get me wrong - the images people take here are simply spectacular and very unique and I really enjoy looking at them but I don't have quite the same patience I don't think!

As an aside I usually stack 30sec shots at iso 8000 (120 or so) with my sony a6000 and the results, while probably not up to the standards here, are better than you might expect. I thought your idea on stacking many shorter images was interesting.

I find it very relaxing on the astrocamps too. Nothing like being out under a black country sky doing a bit of viewing.

Hope you find something that suits for your telescope. Pity it is hard for you to get your SN telescope across to where you are. I guess if you are looking at heavy imaging equipment you may need to modify the focusser as you have said. The starlock technology sounds amazing but I would say setting up and aligning the eq6 is much easier now than it used to be with the procedure that helps you to align the mount. It tracks pretty well and is well aligned for the lower focal lengths (and faster f ratios!) that I use. Some of the newer versions of the eq6 today look even better built than mine.

Keep us all posted on your work. Maybe one day the 1.3meter telescope will be at your disposal!

Hope to see you at a star party some time. Let me know if you are ever heading to south pacific star party.

Best regards
David

AstroStudentUSQ
05-10-2017, 01:58 AM
Hey David,

Yes there are many ways the broader astro community can help with research, see for example the citizen science projects you can participate in at:

https://www.zooniverse.org/projects?discipline=astronomy&page=1&status=live

I often spend some time on them to unwind and relax, try some out! :) Recently with the ABC's Stargazing live, an exoplanet citizen science project ended up discovering a new exoplanet with the many citizen science helpers picking out potential planet transit signatures which were followed up. I particularly like the citizen science outreach ethos, it has science education benefits for all ages which is great and I encourage everyone interested to check it out and maybe get contributing on some projects regularly :)

I've been thinking for some time about Binoviewers too, though most reviews I have read do not speak highly of the more affordable versions, notably Celestron's. I agree that it would be preferable to using both eyes comfortably rather than squinting through one eye, which has never really appealed to me that much. I am hunting down reviews of the famous tele vue bino viewers, but they are around the thousand mark! :eyepop: the other thing is then you have twice the expense of eyepieces, although myastroshop has some quality models which are reasonably priced.

I echo your choice of ZWO cameras, although I may end up going with a OSC version as with my upcoming studies I won't have a lot of time to spend hours upon hours selectively capturing in each band. I have seen some of the upper model ZWO OSC imagers produce some really nice results. Perhaps a OSC version is the right pick for you also with time constraints...

Yeah I definitely wouldn't be doing single very long exposures either, its all a bit archaic. Not to mention risky for a number of things which can stuff up such a long exposure. I intend to stack many shorter exposures, after finding that sweet spot of maximum signal return with minimum noise. With the sensitivity of today's available imagers and available software, there are so many breathtaking images online following this ethos.

That's amazing having that personal connection to Mt Stromlo in the family, you must have had many interesting conversations with your Uncle :)

Yes I will post on the forum about my experiences with astronomy with USQ as I go through the program :) I also hope to make a youtube channel soon and when I purchase my new scope I will post a video of the whole thing which is always fun and quite interesting for many people it seems from the many "unboxing" videos published...

Best wishes to you David and feel free to PM me any time for astro chat :thumbsup:

Cheers,
Mark

Atmos
05-10-2017, 06:38 AM
With binoviewers, if you don’t want to spend a fortune Denis sells them periodically on the classifieds here.



A OSC doesn’t mean that you need to spend less time. Doesn’t change any time constraints. There are pros and cons though. Given the same integration time mono will always give superior results when comparing like for like (ASI1600MM-C vs ASI1600MC-C). Colour has convenience in that you will always have usable data, clouds cannot roll in ruining all your blue exposures requiring another night to be able to process.



That depends on what you call short and long. Using an ASI1600MC-C may allow you to take 15-30s exposures at a higher gain over the 1200s you’d need with something like the KAF-8300 sensor. The difference is that with a deep 20 hour exposure image you are looking at stacking 2,400-4,800 exposures as opposed to 60.

gregbradley
05-10-2017, 08:31 PM
A OSC doesn’t mean that you need to spend less time. Doesn’t change any time constraints. There are pros and cons though. Given the same integration time mono will always give superior results when comparing like for like (ASI1600MM-C vs ASI1600MC-C). Colour has convenience in that you will always have usable data, clouds cannot roll in ruining all your blue exposures requiring another night to be able to process.


Actually it does affect exposure time OSC are routinely a fraction of the QE of mono. That is improving with CMOS sensors used in modern digital cameras like the latest Sony Exmor backside illuminated sensors gapless microlenses and copper wiring.

OSC is a compromise. Every shot counts for sure and that its strength. But equally every shot is way noisier due to the low QE.

I used an STL11 OSC for a while. It was great for the brighter objects but objects that had a lot of dust or were dim showed up way too much noise.
Short exposures won't help there because its simply not recording the faint data in first place, 500 x 0 is still 0.


OSC are great for making every shot count (filtered imaging means you miss getting one of the items needed for a colour photo due to cloud etc).
They are great for bright objects but you won't be able to go as deep as same total exposure of a mono filtered image. They are also relatively poor at narrowband imaging.

Greg.