Astrophotography equipment- last minute questions before purchase

DJDD · #1 09-02-2008, 06:18 PM

ok, i am *almost* ready to fork out some cash for an ED80 and mount for astrophotography, partly because it is my birthday soon and partly because my wife has been bitten a bit with the astrophotography bug after taking some night shots in Nepal.

anyway, just to be boring I have some final (probably *stupid*) questions on mounts, guidescopes, filters, etc., and would appreciate any information.

1. Other than the ED80 and the mount what do I actually need to connect our Nikon D80 DSLR to the telescope? I assume an adapter straight onto the body but are there several bits needed?

2. Filters
I have two questions about filters:
(a) I plan on buying a Light Pollution Suppression filter as I live near Southland shopping centre.
Where does the filter go? At the front of the telescope? or attached to the adapter between the telescope and the camera?

(b) I am also concerned that dust will end up on the front lens of the ED80. Does anyone worry about this?
If so, what do you do about it? Use some sort of Neutral Density filter over the front lens?
If not, how do you keep the lens clean?

3. Auto-guiding
(a) I will probably get a Q-guider or similar
(b) but what do people use as the guide scope for an ED80? I see a few people use an ED80 as a guidescope but...

4. Mount
I will not bore you with questions on the mount

(lots of interesting threads on IIS), except to ask if an HEQ5 will handle the weight of an ED80 + DSLR + guidescope + Q-guider (or similar). Without knowing what the guidescope is it is hard to just compare weights with the HEQ5's specs so any advice is appreciated.

Or should I spring for the EQ6? I realise that the larger load-bearing capacity of the EQ6 will be better in the long run, although if the HEQ5 is ok with the weight then I will not be buying the EQ6. in this case money is a consideration (and I have read the "Which mount for Astrophotography" thread) and I am happy to accept at this stage shorter exposures and lesser quality photos than the big boys and girls here

as long as the photos come out ok (and I have seen some AMAZING photos using the HEQ5.

5. This may be the stupidest question but...

Due to trees, buildings, and other obstructions I will only be able to image objects high in the sky (from about 60% above the horizon to straight up!).
Will the telescope/mount/camera combination handle imaging objects directly overhead? I ask this because my CAMERA tripod cannot do that (when just using the DSLR) without drastically changing the lengths of the legs.

Thanks in advance for any assistance.

DJDD · #2 09-02-2008, 06:20 PM

hmmm...
just after posting i saw this thread

http://www.iceinspace.com.au/forum/s...ad.php?t=28464
How would you rank CCDs + add-ons for auto-guiding?)

that may answer the auto-guiding question.

Zuts · #3 09-02-2008, 07:52 PM

Hi DDJJ

(1) You need a T ring ($40) and a two inch nosepiece ($30). Take off the lens of the DSLR and put in the T ring. Screw on the nosepiece and plug it into the ED80 focuser.

(2) The filter can screw into the nosepiece. Astronomic make good LPS filters. You may also need a UV/IR filter to stop star bloat. Neither of these are immediate requirements, though without the LPS you will probably be limited to 2 minute exposures.

(3) I was using a 70mm Saxon achro as a guidescope. This is fine for widefield imaging with the ED80. These can be got for about $100 if you look around. A better option would be an Orion Short Tube guidescope.$218 from Bintel. https://www.bintelshop.com.au/welcome.htm. Q guiders are great but a 2nd hand Meade DSI ($100) guiding through PhD would suffice as well.

(4) If you can afford the difference I would get a EQ6Pro. At Andrews they are only $1700 which is not much more than the HEQ5 Pro. This would be far more stable.

(5) Other things. Not immediately required but you will need a Focal reducer as initially you will find you get field curvature. You can crop this out. William Optics sells a good one for a few hundred dollars and they can be ordered quite cheaply from OPTCORP.COM.

(6) You will need some way of mounting the guide scope. I got two 'Guan Sheng special dovetail mount adaptor - FF561' from Andrews $49 each. These fit on each end of the dovetail.

(7) You will need a 24 amp hour battery, say from supercheap auto.

(8) You may need two heater straps from bintel to stop the scopes from dewing up. If your camera dews up, literally put a sock on it. Obviously you cant do this with your scope

You can get pretty close to the Zenith. There is no problem with the mount. More of a problem is the scope and camera which may get in the way when pointing straight up. As far as dust is concerned. You dont get much and if you do you can clean it off with some cleaning fluid available from Bintel. A little bit of dust is no problem. Definately dont clean it after each imaging session and just keep the plastic cap on when not in use.
Paul

edwardsdj (Doug) · #4 09-02-2008, 08:38 PM

Hi DJDD,

I concur with what Paul has just said.

When you talk about getting dust on the front lens of the camera, be aware that you will be taking off the lens and using the telescope as the camera lens. Any dust ends up inside the camera. Not on the lens.

I personally would consider the EQ5 as adequate for the type of setup you describe (with a small guidescope). Certainly nothing more though! If you wanted to use a larger telescope or any additional equipment, you would need the EQ6.

People do get great results with the EQ5 but will be pushing thier mount far harder than those with the same setup on an EQ6. You can get away with less but it takes far more careful attention to techniques to get good results. If you get better equipment you can get better results with less frustration. This is always the tradeoff

Have fun,
Doug

Zuts · #5 09-02-2008, 09:06 PM

Hi DDJJ,

I forgot but for guiding on an EQ6 you will need some way of attaching the guide camera to the mount. For a DSI you would plug the DSI into the laptop and then run a cable from the laptop to the mount. This cable can be got from shoestring for about 80 bucks. I have one and it is fine. With a Q guider you may not need this.

Now the good news, free software you may use

PHd guiding, for guiding.
DSS (Deep Space Stacker) for stacking your images.
Focus Assist to help you focus.
IRIS to help you post process your images.

Hope this helps

Paul

alan meehan (Alan) · #6 09-02-2008, 11:09 PM

hi DJDD,
go with what paul has said ,i would look towards a eq6 than if you want to put alarger scope on you can,i have one with a c8 and a orion f5.6 short tube as a guide scope,and it is such agood mount value for money.
orion short tube is ideal for a guide scope,and bintel sell the mounting rings as well. cheers

seeker372011 (Narayan) · #7 10-02-2008, 12:59 AM

Quote:

Originally Posted by Zuts

free software you may use

.....
Focus Assist to help you focus.

Googling didnt help find this freeware..do you have a link?
thanks

Zuts · #8 10-02-2008, 01:27 AM

Quote:

Originally Posted by seeker372011

Googling didnt help find this freeware..do you have a link?
thanks

Sorry DJDD,

This may only work with Canon cameras
http://www.xmission.com/~jstanley/focusassist/

This is useful as well, it allows you to magnify the image

http://www.iconico.com/magnifier/

Paul

DJDD · #9 11-02-2008, 07:37 AM

heh, thanks for the replies, everyone.
sorry I did not reply earlier to your posts but I got pulled this way and that on the weekend and did not get much chance to look at the forums.

Zuts, thanks for your initial detailed post and follow ups.
Focus Assist does work with other DSLR's but in a capture-mode.

It is the details provided that make some difference- a $2200 purchase can spiral out another $500 in little bits and pieces and really needs to be factored in.

thanks, again.