Help needed

Akwestland (Andrew and Kim) · #1 07-02-2015, 01:17 PM

Hi all, I am very new to telescopes but am learning, a slow process, but worthwhile. I am seeking a little bit of advice on astrophotography.

Before people tell me not to get in to astrophotography at this early stage I would like to make a statement. I am not looking to do this this year. I need to learn much more first.

I need to buy myself a half decent digital everyday dslr. Something I have been wanting to do for some years. I am not in the habit of updating things like cameras every year so I would like something that may be half reasonable to use as an intro to astrophotography.

I am currently looking at this ( http://www.ryda.com.au/ProductDetail...=D530055300BKT ). I have a fair background in photography (4 years of schooling - pre digital) and even larger background in computers (very few programs scare me). The budget is around $1000 and I am always concerned about cheap imports that have to get sent back to China for repairs/also ones where the menu language is in Arabic or Spanish. Also does anyone have any experience dealing with Ryda Dot Com in Sydney?

The initial use is everyday use but maybe to move on in time.

I am reading lots about astrophotography but I am having trouble creating a list of what to look for and what to avoid. I hope this all makes sense.

If it makes a difference I am using a Celestron Nexstar 4se. If anyone can suggest easy to understand online resources that would be great. I have read several articles/tutorials on this site, they have been great reading.

I look forward to your responses.

Andrew

traveller (Bo) · #2 07-02-2015, 02:16 PM

Hi Andrew,
There are 3 critical parts to AP, the scope the mount and the camera. First of all I don't think your 4se is suited to any long exposure AP work. It has a long focal ratio of f13 means it will need long exposure to get the image exposed.
This means the mount has to be tracking very well and guided to minimise any star trails. Again, the 4se single arm fork mount is not suited to this task, 30 sec is probably the best you can aim for.
As for the camera, the major draw back of a stock DSLR is that it's not sensitive to the Ha region as a filter has been placed in front of the sensor to mimic the human eye response. That's why you see a lot of people modifying their DLSR to make them more Ha responsive.
The way I see it, you can try the following options.
Get a EQ mount, a Heq5 would be the minimum and eq6 is a proven performer theses come up often in the classifieds from 600-900 depending on age condition etc.
get either a fast Newtonian 8" f5 (f4 if you don't mind the collinmation fiddles) or a wide field refractor like ed80. Refractor will get you more contrast, but requires long exposure as their focal ratio is usually around 6-8 or more. Theses are around 350-450 second hand.
Camera wise, a DSLR is a good start, there are dedicated programs out there such as Backyard EOS which are very popular. You can get a 60d or the 60da version if you want to splash out, or get a second hand dslr and mod it for astro use.
All up, you need around 2k get going.
Finally, go to a star party or an astro camp (like the one Malcolm is organising at snake valley). You will see all combinations of set ups and can ask the pros and cons of each!
Bo

multiweb (Marc) · #3 07-02-2015, 02:32 PM

+1 All that Bo said. Go out one night, see gear, ask plenty of questions before making any decision. Best advice to save you money and heartache later on.

Akwestland (Andrew and Kim) · #4 07-02-2015, 03:10 PM

Bo & Marc,

Thank you for the replies. I had a bit of an idea that may have been the case. We may still get this camera for everyday use (We have a grandchild about to be born

).

When the time comes and the Minister for Finance (bought the scope for Her

)allows, then scope 2 and 2nd hand modded camera/ccd may eventuate. Learning the new processes (collimation, polar alignment) is all a part of the challenge.

I would love to go to a star party, that I would really enjoy. We live in Far East Gippsland near Orbost on a small farm, there does not seem to be much out here in that regard. I do travel to Melbourne for work almost on a regular basis, normally on a Friday night for a meeting on Monday, I have thought of going to an MPAS open night, but, early start for work, finish here at 5pm, drive down (4 hrs), arrive 9pm, fall asleep

. Can you see the problem that I have.

Cheers
Andrew

Akwestland (Andrew and Kim) · #5 07-02-2015, 05:02 PM

Bo, further to my response:

Your statement:

Get a EQ mount, a Heq5 would be the minimum and eq6 is a proven performer theses come up often in the classifieds from 600-900 depending on age condition etc.
get either a fast Newtonian 8" f5 (f4 if you don't mind the collinmation fiddles) or a wide field refractor like ed80. Refractor will get you more contrast, but requires long exposure as their focal ratio is usually around 6-8 or more. Theses are around 350-450 second hand.

My understanding:

So an 8" Dob would require a shorter exposure time as opposed to a refractor?

Mounts - is a "goto" mount going to come close enough on a dob?

Sorry if these sound like idiotic questions, but I am trying to get my head around this.

Since we were lied to when we bought the 4se (by the sales people) we are thinking of using this as a secondary and "grab 'n' go" scope. We found out that what the Wife wants to view maybe be possible in a 12" Dob or similar. Yes we got ripped off.

Again, sorry if my questions are redundant.

Cheers
Andrew

traveller (Bo) · #6 07-02-2015, 07:15 PM

Hi Andrew,
Yes, as a general rule, a 8" Newtonian has more light gathering ability than a refractor (unless the refractor has a diameter of more than 8"!).
The exposure time is dependent on the f ration, just as a f2.8 lens is "faster" than an f4 lens, a f4 or f5 Newtonian will require much less exposure time than an f6.5 or 7.5 refractor, even if that refractor is 8" in diameter (when 5" refractors are considered big).
As for goto, it's simply a set of computer controlled motors. Once you enter key data such as your location (latitude and longitude) date and time, the onboard computer will be able to power the motors to point the mount (and therefore the scope attached to it) to a preset locations in the sky (then you will need to fine tune, depending on how accurate your polar alignment is).
Just to confuse things, you can get goto dobsonians (simple dobsonians don't have the goto kit with computer and motors, but like everything else, you can upgrade non-goto dob to a got dob, clear as mud????).
The key here is a goto dob is on an AZ mount, where the mount needs to track in both altitude and azimuth planes whereas an eq mount only needs to track on the right ascension (RA) plane once the declination plane (dec) is set via the altitude bolt on the eq mount.
You can do planetary imaging and short exposures of 30-60 secs on a goto AZ mount, but for lingers exposures, a eq mount is almost a must.
Hope that clears things up a bit!
Bo

traveller (Bo) · #7 07-02-2015, 07:20 PM

Just on the 4se, it will be a great grab and go scope, esp in darker skies of the country. It won't show up much detail on the faint galaxies and nebulas, but great for the planets and bright objects like globular clusters.
I think the 4se mount has a built on tilt "wedge" you can use that to see what the limits are in exposure time.
Bo

Akwestland (Andrew and Kim) · #8 07-02-2015, 09:11 PM

Bo, I should have mentioned that I do have a reasonable understanding of how the f stops work in relation to exposure. I have played a lot in photography including 4 years of p/t schooling.

I also should have mentioned that the 4se has goto, so I am learning all about that at the moment. When we bought the 4se we were told that we would be able to see the Horsehead Nebula. We have since learnt that that is no where near possible. And I have also been told that you cannot upgrade a Dob to a Dob with goto, I didnt really understand why. I have since been reading about argo navis (sp).

I have been getting my head around AZ mounts, even though with the 4se it does not really play a part. I hope I am right in that statement. the 4se also has the wedge, I have not even started playing with that yet. So far I am simply setting it up (when we have no clouds) including alignment so that it tracks, and sighting a few items, not many, at this stage I simply have a 25mm EP and a 2 X Barlow. So a little limited.

Maybe a silly question, how does a larger Dob go on an AZ mount? It seems way too big from what my limited experience tells me.

Most of what I am learning is from sitting here reading. As I live on a farm I do not know anyone else that owns a telescope. For this reason I am greatly reading any responses I get, and then I read them again.

I am enjoying the learning though.

Cheers
Andrew

traveller (Bo) · #9 07-02-2015, 10:14 PM

Hi Andrew,
Didn't mean to lecture you about u on f stops, just my way of comparing things. The salesperson needs to be taken to the accc as it just isn't possible to see the horse head through the 4se

Back to your question about dobs on an AZ mount, are you referring to the Newtonian tube on an AZ mount like your Se mount? Dobsonians by definition is already sitting on an AZ mount, just a manual one.
Some AZ mounts can carry a 8" Newtonian OTA, like the ioptron minitower https://www.ioptron.com/index.cfm?se...c-1045d25b0651. But it still has limitations of an AZ mount for astrophotograghy work.
Mounts have rated carrying payload capacities, for visual observation, you can push the mpunt to their rated limit, provided you balance the mount. For photo work, you should do about 70-75% of the rated capacity only.
There are lots of big dobsonians with Argo navis, SDM being one of them http://www.sdmtelescopes.com.au
So yes, it is possible to carry a Newtonian OTA on an AZ mpunt or eq mount, or if you're into visuals, then a true dob with or without goto and the wallet is your limit

Bo

Akwestland (Andrew and Kim) · #10 07-02-2015, 11:01 PM

Bo,
I did not mean to offend you with my comments, and there was definately no offence taken here. I know from a newbie perspective that aperature can be difficult for some to understand, so I understand and agree with what you said.

When we bought the se4 was still deciding, the choice was this or a dob. When we were told that we could see the HH then the decision was made. Maybe not enough research on my behalf, I do not know. As we have a caravan and go camping then we decided it could work for us, although limited.

In regard of the mounts, I am suspecting with the amount of reading I have done that I am now confusing myself. A standard Dob as seen here http://www.bintel.com.au/Telescopes/...3/catmenu.aspx is a AZ mount? So when they set them up they need to be set for polar alignment i believe. For the goto, to upgrade a standard you need Argo Navis and Servocat to create a goto. Using Argo Navis just gives you a "push to" is that correct.

As for those SDM Scopes, that is some very serious aperature there. They are awesome.

I hope that I am not boring you with all of the questions but I am learning a lot from this, and I thank you.

Cheers
Andrew

raymo · #11 07-02-2015, 11:33 PM

There is nothing to stop you upgrading a Skywatcher Dob to a Go To
one, just that the kit is quite pricey, around $900. Much better to get a Go To in the first place.
raymo

Akwestland (Andrew and Kim) · #12 07-02-2015, 11:49 PM

Raymo,

You have echoed my thoughts. I could not see how an upgrade was not possible. But yes I do believe that it is cheaper "out of the box" as opposed to "add ons".

But at the same time if it has to be a progression financially, then so be it. At least as a progression it does give one time to learn and observe. I was largely limited in our first purchase by a budget, as I am sure that we all are.

Cheers
Andrew

raymo · #13 08-02-2015, 01:58 AM

IMHO, much better to get familiar with the sky before moving on to
a Go To scope. Much more satisfying.
raymo

Akwestland (Andrew and Kim) · #14 08-02-2015, 10:32 AM

raymo,

I do agree with your statement. I am also doing this on a nightly basis, we live on a farm and we have chooks, every night before I go out to lock them up I look on programs like The Sky X and Cartes du Ciel, look at what I know and target a couple that I want to know. Then when I go out I start from my regular spot Orions Belt and star hop to find what I hopefully was targeting. When I do this I also re-cap on most of what I know so far, or at least the main ones.

I am enjoying this method, have not yet created a complete constellation visually yet, but I am sure it is there somewhere.

Thank you for the advice.

Cheers
Andrew

traveller (Bo) · #15 08-02-2015, 02:27 PM

I will second what Raymo said Andrew,
Yes, all dobs are on an AZ mount because their base rotates and controls the azimuth and the pivot in the middle of the tube controls the altitude. A dob without the dob base and pivot is just another Newtonian OTA, and you can mount that OTA on an eq mount, computerised goto AZ mount or a dob mount.
There are a number of apps that allows you to track and identify objects in the sky, and you can get a smart phone bracket to mount on your mount or scope to help as well.
Bo

barx1963 (Malcolm) · #16 08-02-2015, 05:12 PM

Quote:

Originally Posted by Akwestland

In regard of the mounts, I am suspecting with the amount of reading I have done that I am now confusing myself. A standard Dob as seen here http://www.bintel.com.au/Telescopes/...3/catmenu.aspx is a AZ mount? So when they set them up they need to be set for polar alignment i believe. For the goto, to upgrade a standard you need Argo Navis and Servocat to create a goto. Using Argo Navis just gives you a "push to" is that correct.

Andrew
Just to clarify on your comment above. Dobs do not need polar alignment, that only applies to an Equatorial mount. Not having to bother with Polar Alignment is one of the attractions of a dob.
I have never used a go to dob and am unlikely to do so. I use Argo on my 20" and it was also on my old 12" and that is all I need for visual use. Others prefer full go to, but it is a personal thing. Virtually all dobs can be fitted with Argo.

I would urge taking a weekend to attend a party, best way to learn and if you want info on the Snake Valley camp coming up there is a link here http://www.iceinspace.com.au/forum/s...d.php?t=130984 or PM me.

Malcolm

barx1963 (Malcolm) · #17 08-02-2015, 05:35 PM

Andrew
In relation to the Snake Valley Camp, I can pretty well guarantee we will have, on the visual side of things, an 18" fully go to SDM 18", my push to with Argo 20", a completely manual 12" Bintel/GSO dob and a manual 16" truss dob. On the imaging side there will be a variety of EQ mounts and various imaging setups so it could be valuable to see how all these work.

Malcolm

Akwestland (Andrew and Kim) · #18 11-02-2015, 10:23 AM

Malcolm,

I appreciate your input on this as well. I am now getting a much better understanding of the different set ups.

As for the Snake Valley Camp, I think we are in Melbourne that week, which is good. I am trying to convince my wife that one night there would equate to 3 months, or more, of reading/research. I feel that a lot of understanding could be had. We have a lot on that weekend but I am working on it.

I may not know until the last minute if we are to attend, this being the case do we have to book or can we just turn up. We will not be staying there, I understand you would have to book to do that, I would like to get there mid afternoon so that we have time, if permissable, to view different setups and configurations in daylight. Then stay for the evening session followed maybe by some observing. We may have to go back to Melbourne (Frankston) that night though. Unless I can convince the wife to stay on that side of town somewhere.

I would also love to "compare" what can be seen with what.

Cheers
Andrew

traveller (Bo) · #19 11-02-2015, 02:21 PM

You won't regret coming Andrew, just convince SWMBO the trip is for study purposes only

Ballarat is only 30km away from Snake Valley and there are plenty of accommodation options there.
Hope to see you there.
Bo

Akwestland (Andrew and Kim) · #20 11-02-2015, 03:11 PM

Bo,

Thats what I was thinking for accommodation, if we end up staying over there. And it would be great to put a face to some of the names on here, but more importantly the learning that could be achieved.

Cheers
Andrew

p.s. making a doctors appointment to get a shot to protect myself from the dreaded aperature fever just in case.