10” Newtonian Imaging Setup…Equipment compatibility & considerations:

[Davekyn (David)]

10” Newtonian Imaging Setup…Equipment compatibility & considerations:

After much researching and contemplation, I have pretty much decided on the following setup to give a good all round base, for a wide variety of Astrophotography for a newbie such as myself.
Telescopes:
Skywatcher SW-252 Focal Ratio 4.7
254 x 1200P EQ6 Go-To mount with V3.0 Go-To hand controller
parabolic mirror made from Pyrex glass. diffraction-limited secondary mirror support. 2 focuser. one 2 eyepiece. a 2 -1.25 eyepiece adapter. and a 9x50 finderscope.
Question. Can I still move the secondary mirror without messing up the "diffrationilimited support?"
Orion EON 80MM refractor… guide scope & wide field photography as well.
The Mount is an SW EQ-6 V.30 Goto…There does not seem to be to much negative feedback with this combo, but I am open to considerations. I believe wind can be one with a setup like this?
As for what camera…I don’t know…here are some questions I have after reading through some posts on the subject of Newtonians & imaging.
“Just be aware that most Newtonians won't come to focus with a typical DSLR at prime focus. You'll need to move the mirror up the tube or get a very low profile focuser”.
Possible solution? What is a typical DSLR…Is there a type of DSLR where this is not a problem. Is a different type of digital camera such as a dedicated chip that may be used…if so how would it’s performance rate compared to the collimated method using a DSLR?
“Depending on your chip size in the camera you may need to put in a larger secondary to fully illuminate the FOV and likely replace the focuser for one that's more precise”.From what I can gather…there seems to be an element of compatibility issues with the types of Digital cameras, type of telescopes, focal Ratios & so forth when attempting astrophotography. What I would like to know, with this comment…Is the recommendation of a larger secondary mirror something one still has to worry about, if I have already implemented the “move the mirror up the tube or get a very low profile focuser” option? Or is this POINT soley depedant on the size of chip in camera?
Q. If I alter the secondary for DSLR prime focus…I take it, this is best left like this & I use a cheap Dob for Observing?
sorry for so many questions...Ive ordered a book but i dont think it will cover everything & many of you make good points.
Cheers
Dave

[Davekyn (David)]

Just noticed the mount is not a Pro series:
I wonder how much better off I would be getting a pro mount and scope seperately?

SKYWATCHER PRO SERIES MOUNT WITH GOTO $1995AUD or $1490US or £832
The new Pro Mounts from SkyWatcher have been engineered to a higher level of accuracy with very strict quality control. The Mount is modeled after the Heavy Duty EQ5 and includes SkyScan. The Mount's colour is white.

But an EQ6 not 5

[Tandum (Robin)]

Dave,
I had a hard time reading through all those colours and fonts but from what I gather you are looking at an EQ6 with a skywatcher 10" newt and an expensive orion 80mm as a guide scope.

I don't know why you are worried about the secondary mirror or why you would want to move it. I think you have your wires crossed there.

I dunno what needs to be done to the skywatcher 10" newt to obtain prime focus with a canon DSLR. I had an 8" skywatcher dob and simply changed the focuser to a low profile cayford style which did it for me. I then added a 38mm extension tube to get focus with an eyepiece. If you chose a real Astro Camera instead of a DSLR, that may not be needed.

The EQ6 and EQ6pro are basicaly the same thing. The pro has a goto computer out of the box while the EQ6 can have goto added later. I'd get the goto straight up, it's cheaper in the long run. They are currently available for around $1500. In shops here they call it the EQ6 SynScan for some reason, but some still call it the pro version.

I recommend you slow down and do one thing at a time, working your way up to the setup you are talking about, learning as you go. It will save you a bucket load of money in the long run. Get the Newt, learn how to drive it, then plug in a camera then a guide scope and guide camera. Some Astro cameras have a secondary guide camera built in, so a guide scope is not required.

It is a very steep learning curve if your not familiar with eq mounts etc. The eq6 with a 10" newt on it will be very heavy and hard to move about in the first place. Once you load it up with guide scopes and cameras it will be a monster.

[Tandum (Robin)]

The other thing is what do you want to image? The Focal Lenght of that newt (1.2meters) is only a little over double that Orion (.5meter), which is a fair guide to imaging ratio but you could use a focal reducer on the newt to get the same FL as the orion so a cheap guide scope might be better. You will probably want a coma corrector for the newt as all newts introduce coma into the image.

If you want close up views of things you will want a longer focal length which you'll only get from some sort of SCT scope. AlexN is talking about imaging Jupiter with his new scope at a 14meter FL. He will use barlows to get there and he will use a video camera not a DSLR to image the planet. He recons that will fill the chip on his imaging camera.

Basically, don't rush into anything. Figure out what you want from the setup and buy appropriately.

[Davekyn (David)]

Thanks for the reply Robin,

Yea, I guess I am excited, but I got enough time on hand at the moment to get stuck into it & enjoy doing so. With so much info out there on the net, books & magazines, it seems I get a bit of practice while saving. Nothing beats hands on though. I don’t believe I’ll be wasting any money –I never do with my purchases- but thanks all the same. I understand what you’re getting at. Oh yea most people find the highlighting more useful to read though; if anything I should of spaced out the format.

To answer your question:
“I don't know why you are worried about the secondary mirror or why you would want to move it. I think you have your wires crossed there.”

I thought the secondary mirror was the one to move in relation to DSLR Prime focus with Newtonians? If I have this wrong, could you shed any light on the subject?

The reason I highlighted was to clearly show what statements in some of the forums I was having a hard time understanding…Obviously not everyone will understand either or perhaps my questioning and format, as you say, is too hard to read?, but I think it’s clear why I thought the mirrors had to be moved.

Thank you for bringing to my attention “the focuser to a low profile cayford style + inclusions of compatible extension tube” This must be dependant on the camera as I can’t understand why people would go to the trouble of moving mirrors for prime focus if this method works.

Here is a specific question for you?
What do you mean by “real Astro Camera” is like that what some call a dedicated digital sensor for astro usually small as if house in something the size of a salt shaker?

With the mounts I was referring to the Quality control & finer tracking control with higher level of accuracy…This I would of thought the pro model more worth of purchase due to these attributes was all.

As for what type of photography…MMMM…I was going to be happy with wide feid on an ED80mm and use the Newtonian for Planetary type stuff. I was wondering if the FL on that model was up to it though. Thought I better not ask to many questions….hahahahahahaaaa…LOL…But I am GLAD you brought it up:

Here is some shots of Planets with that scope…but then again I wonder how much of a gimmick it all is…as I cant find toooo many dedicated image pages as I can with other scopes out there:
http://www.myastroshop.com.au/guides/sw252.asp

Honestly…Thanks heaps for chatting…I need all the help I can get, Thanks for your concern about me getting carried away and all that…I’m just that kinda guy J and although sometimes it lands me in trouble only to be more confused than when I started, I usually end up with a much better idea of what I am getting myself into. Just consider me one of those complicated guys that has to do everything the hard way.

I am a bit thick, but it does not worry me,,,its why I seem to be able to hit my head against a brick wall twice as long as most, even though I only get half the answers. I even have to stare 10 times longer into space to find what others find easily…We all learn differently. But WOW,,,I’m starting to enjoy reading stuff I don’t understand like when I stare into space in awe…eventually it will sink in…I know I have met some really interesting people.

Thanks again Robin…I will check out your methods for sure!!! Please let me know if there is anything else about this post you don’t understand. I will only be to happy to clarify.
Dave


PS…For anyone else…
The Other suggestion I found hard to understand was about replacing the “Size of the secondary” In to match the size of the cameras sensor chip. Once again, my thoughts & misconceptions have been also noted, but it’s no biggy. I have a book underway from Amazon, or I’ll simply find out as I continue to research these finer points…I’ll try to slow down as you say…but don’t really feel out of breath at this stage.

[Alchemy (Clive)]

Originally Posted by Davekyn

To answer your question:
“I don't know why you are worried about the secondary mirror or why you would want to move it. I think you have your wires crossed there.”

I thought the secondary mirror was the one to move in relation to DSLR Prime focus with Newtonians? If I have this wrong, could you shed any light on the subject?

but I think it’s clear why I thought the mirrors had to be moved.

Thank you for bringing to my attention “the focuser to a low profile cayford style + inclusions of compatible extension tube” This must be dependant on the camera as I can’t understand why people would go to the trouble of moving mirrors for prime focus if this method works.

Here is a specific question for you?
What do you mean by “real Astro Camera” is like that what some call a dedicated digital sensor for astro usually small as if house in something the size of a salt shaker?

PS…For anyone else…
The Other suggestion I found hard to understand was about replacing the “Size of the secondary”.

you are the chatty one indeed......

ok

1. secondary stays put .
2. Dont cut or modify until other options considered
3. If you want to cut, then its easier to move the bottom miror up, there an article here on IIS that tells you how to do it by someone whos done it (me).
4. You will need a BAADER MPCC (multi purpose coma corrector) this also changes the focal length so check before you buy another focuser or cut
5. Low profile focusers may not be that stable (GSO version isnt) so take that into consideration
6. All cameras will take astrophotos, ones dedicated to only Astrophotography such as SBIG ( Santa Barbara Instruments Group) are specifically desgned for this purose only...... you wont be taking snapshots of the kids with these too often, these are considered "real astro cameras" but hey they all work... some better than others, keep in mind some of these cost over 10,000 dollars.
7. most secondarys are larger than required so a 75mm one might be replaced with a 60mm one ..... this needs to be carefully determined.


there are many modifications and enhancements that can be done , but its best to learn to walk before you run. a 10 inch scope and eq6 will produce fine results, master these then worry about the intricate little things to get that extra 1 % better image.

i use a 12 inch cheap old GSO Newt thats only had a 50mm cut to the rear end no other mods like flocking, smaller secondarys etc my latest image below. note theres not a lot of difference to a 10 inch so what you are considering is fine.

[Davekyn (David)]

Whatever it Takes...well not quite...OK...Puts stern voice back on..

Thankyou...for being specific. Points well taken and noted! SBIG hey...I've heard that one several time before...will check it out for alternative as well.

Thanks for clarification on mirrors...check!

Multi purpose coma corrector....WOW..I like! will investigate....

Infact I dont have time now...but allow me to come back and query later.

Thanks heaps...excellent response!!!!
Later

[netwolf]

In my opinion the SW-252 while being an good option is overpriced, 400-500$ would be a fair price for it. But it sells for almost 1000$. The equivalent dob tube is heavier and may not work with the same tube rings. It is the same OTA as the Celestron CN-10.

Eric (ezystyles) uses the same setup and has done some fantastic work with this setup. Check out Eric's website and see what can be done.

[Davekyn (David)]

Thanks Netwolf,
I have the SEPT edition of Australian SKY & Telescope & found some of his work in there. I have favourited his site. Good call