Scope+mount for astrophotography?

luka · #1 09-09-2007, 03:04 AM

Hi,

I delayed my decision to get a dob due to my trip to Europe but now I started changing my mind and thinking again what to get. Choices, choices...

1. What would be a better setup for starting in astrophotography (and casual observing):
8" dob with tube mounted on HEQ5 or ED80 on EQ5? The cost of the two setups seems to be similar.

2. Which would give better imaging quality?

3. How much more can be seen with an 8" dob compared to a small refractor like ED80?

4. What are advantages of GOTO mounts for astrophotography except that they make it easier to find the target?

Thanks guys, your help is greatly appreciated.

[1ponders] (Paul) · #2 09-09-2007, 12:39 PM

While the HEQ 5 would probably handle the Dob tube, for astrophotography I'd suggest the EQ6. Don't forget you will need an additional scope to guide through so this will add additional weight, plus guide rings and mounting bar plus camera, adapters, cables yadda yadda. All of which, while only small in individual weight quickly add up.

I can't comment on the 8" dob for image, as I like my ED80 (much easier to learn with as it has a shorter focal length, plus it is easier to get Focal reducers for it.), but the dob has a faster f ratio which is a bonus. BTW if you use an 8" dob, I don't think the standard tube rings will fit it, you may need to get special ones made up. I looked into do this with a 10" dob and the dob tube was much wider (by about 30mm) than a standear 10" newtonian tube.

Don't forget cool down, ED80 cools much quicker than a newt. Collimation is also needed for the newt while the 80, once collimated should stay there unless dropped or similar.

Also what are you going to image? How are you going to control your guiding? What you can image (ie what can be seen with an 8" dob compared to ED80) depends on your exposure time, f ratio, field of view and a whole range of variables. The ED80 will do lovely moderately wide field shots where as the 8" will have a much narrower fov (82x125 arcmin for ED80 and Canon 300D and 41x62.4 arcmin for an f6 8" newt and canon 300d).

As for goto. If it works its great if it doesn't it can be a pain. Generally it does make life a lot easier though.

Hope that helps.

Hagar (Doug) · #3 09-09-2007, 03:26 PM

Difficult desision.
A couple of points to remember.

Dob will probably require some mods to allow a camera to come to focus. (Shorten tube) and then may require an EP extension to bring an EP to focus.
You will need tube rings to mount it on EQ base.
Possibly require more counterweights to balance the scope.

ED80. This would be my choice and actually was my choice. A realy great little scope but remember it gives a fairly wide field of view and requires good tracking to allow better than 30 second exposures. It matches beautifully with my Canon 350D.

I hope this helps.

Doug

luka · #4 10-09-2007, 02:55 AM

Thanks, that was of great help. I am leaning towards the ED80 now.

Regarding visual observing, how much can be seen with the ED80?

Also without GOTO, how do you guys find the faint objects in the sky that you want to image if you cannot see them?

And finally, what is the difference in the ED80 and the Pro ED80 (except the higher price)?

Thanks again

[1ponders] (Paul) · #5 10-09-2007, 09:20 AM

Can you post a couple of links for the ED80 and Pro. My understanding is that all the ED80s are basically the same scope with different colours and badges. I think the Pro includes a goto mount as in this one from www.myastroshop.com.au

Pro ED80

Quote:

Also without GOTO, how do you guys find the faint objects in the sky that you want to image if you cannot see them?

We're just reeeaallly good.

Nah most use star maps, either hardcopies or with a planetarium program and then star hop to the area..

Quote:

how much can be seen with the ED80?

Heaps actually. Don't expect to see mag 13 galaxies but there are plenty of other objects to see, including brighter galaxies.

luka · #6 10-09-2007, 04:27 PM

Quote:

Originally Posted by [1ponders]

Can you post a couple of links for the ED80 and Pro. My understanding is that all the ED80s are basically the same scope with different colours and badges. I think the Pro includes a goto mount as in this one from www.myastroshop.com.au
Pro ED80

Have a look at
http://www.andrewscom.com.au/site-section-10.htm
select Skywatcher and then search for ED80. Halfway through the page:
Clearance:
ED80 x 600 OTA only...A$499
...
and further down the page:
Skywatcher PRO series Optical Tube Assemblies (OTA)
Model Price $(AUD)
PROED80 ED Apochromatic refractor 80mm x 600mm OTA only $800.00

There is not much more description on the page but there is $300 price difference. Both OTA only so I thought something must be different.

[1ponders] (Paul) · #7 10-09-2007, 04:45 PM

It is confusing that's for sure. I went and had a look at Bintel and come up with these
https://www.bintelshop.com.au/Product.aspx?ID=7443
https://www.bintelshop.com.au/Product.aspx?ID=7285
https://www.bintelshop.com.au/Product.aspx?ID=7290

and it looks as thought they are all the same telescope.

All I can suggest is to give Andrews a call.

Starkler (Geoff) · #8 10-09-2007, 06:24 PM

Quote:

Originally Posted by luka

Regarding visual observing, how much can be seen with the ED80?

Not enough to satisfy me and IMO shows little more than binoculars. I had one and then later sold it as I have no interest in doing astrophotography.

To those looking to start out with visual only, i usually suggest a dob. For those that want to do AP, you cant go wrong with an ed80 on a decent eq mount.

For those that want to do both, I suggest buying both because the compromises required to satisfy both requirements in one scope (at the budget end at least) are too great IMO.

luka · #9 10-09-2007, 08:04 PM

Quote:

Originally Posted by [1ponders]

It is confusing that's for sure. I went and had a look at Bintel and come up with these
https://www.bintelshop.com.au/Product.aspx?ID=7443
https://www.bintelshop.com.au/Product.aspx?ID=7285
https://www.bintelshop.com.au/Product.aspx?ID=7290

and it looks as thought they are all the same telescope.

All I can suggest is to give Andrews a call.

Bintel has Pro and non-Pro ED80s as well. Or not?
If you look at your first link the title says ED80 but the description talks about ED80 Pro. What is going on?
I may email Andrews and see, phone call is out of question as I am in Italy at the moment.

Quote:

Originally Posted by Starkler

For those that want to do both, I suggest buying both because the compromises required to satisfy both requirements in one scope (at the budget end at least) are too great IMO.

Yes, I am aware of this. One professional tool serves only one purpose, for anything else it is a compromise.
If the budget permitted, I would be having both. Seeing how many telescopes some of the people in these forums have

dugnsuz (Doug) · #10 10-09-2007, 08:33 PM

Hi luka,
I own a Skywatcher ED80 Pro - the gold one with white trim.
From my experience, all ED80's are basically the same scope with the branding being the only difference. That said, the Bintel special price of $599 looks the best value around as they supply dovetail, tube rings and finder+bracket with the OTA. Andrews has the same scope only at RRP.

My mount is A Skywatcher EQ5 with SynScan Goto ($1100 - sure that price'll drop soon too) - I had initial problems with the GoTo but have now sorted that out and so far I'm happy. I'm yet to train the drive (PEC) for astrophotography and pursue the autoguiding capabilities also, so it's a work in progress. I considered the HEQ5 too but the extra $400-500 could be employed elsewhere and the ED80 is solid as a rock on my mount. I want to add a guidescope in the future and I'm confident that this will pose no problem - a heavy reflector OTA would be a problem though I think. You can check out some pics of the setup and read about the problems I had in the following thread...
http://www.iceinspace.com.au/forum/s...ad.php?t=23582
Cheers
Doug

dugnsuz (Doug) · #11 10-09-2007, 10:09 PM

On reflection that link might not be the best endorsement for the mount!!!
I'm happy now - honest!!!!
Doug

monoxide · #12 10-09-2007, 11:22 PM

if you plan on doing a bit of observing through the scope as well as imaging this might be worth considering
https://www.bintelshop.com.au/Product.aspx?ID=7379
it will give pretty close to the same fov as an ed80 but being 6" it will also allow you to 'see' a lot more, certainly a very nice ota to look through especially with my 24mm Panoptic.

if you were going to purchase this ota i'd ask if bintel could fit 10:1 low profile focuser for you which will definately make it a lot easier for imaging.

its also probably worth mentioning that once you get started you will almost definitely want a coma corrector like the MPCC/Paracorr. and for what its worth i will be using a MPCC as its a lot cheaper than the Paracorr and doesn't affect the focal length.

luka · #13 12-09-2007, 01:20 AM

I got answer from Andrews regarding the difference between ED80 and ED80 Pro for those who are interested:

Quote:

I made some investigations today and we believe the ED80 uses FPL51 glass, whereas the ED80 PRO uses FPL53 glass. FPL53 is noticeably superior to FPL51 and I had seen the statistics and optical performance difference on the internet a few weeks ago in checking something else.

I believe the ED80 PRO has a 10:1 Crayford style focuser whereas the ED80 has only a normal Crayford style focuser (no vernier reduction drive). We checked a ED80 this morning at the shop, but not a ED80 PRO, yet.

Also, the ED80 PRO has a gold tube colour and white coloured tube rings.

Skywatcher's website does not even mention ED80 (non-pro) so I assume this is their old model that is not being produced any more.

dugnsuz (Doug) · #14 12-09-2007, 08:03 AM

My ED80 Pro doesn't have a 10:1 focuser

Doug

Hagar (Doug) · #15 12-09-2007, 09:47 AM

I understood the diference between then was the pro comes with:
EP's, Diagonal, Tube rings and dovetail bar, gold and white colour and an aluminium case for the OTA. Bintel sell the pro OTA without the diag, EPs and case for $599.
As a scope for astrophotography I would recommend it. I have the HEQ5, a little dearer than the EQ5 but a big solid mount. Some initial problems getting use to drift alignment but that was it for me.

Doug