Beginner Equipment: Dob's on a EQ Mount

[Aaron]

Hi Everyone,

I'm looking at purchasing a 10" SW Dob for general viewing but I would like to eventually get into astrophotography. I've heard that the easiest way to do this without buying two scopes is to use your OTA off the dob and put this on a EQ mount.

Is this correct and would the OTA dob brackets get in the way on mounting it to a EQ mount?

Cheers,
Aaron

[Peter.M]

It depends on what your photography standards are, mine are fairly high and I can tell you that to get a dob to do astrophotography you are going to need to tinker with it alot more than just taking it off the dob mount. Also a 10 inch newt weighs alot and you are going to be looking at a fairly heafty mount to hold it.

I bought an 8 inch newtonian for astrophotography and to get it to work as I wanted it too I needed good collimation tools, a coma corrector, and a new focuser. Now that I am planning on using an off axis guider I need more backfocus so I need to move the mirror up the tube a bit. You would probally need to replace your secondary mirror too being from a visual dob. After all of this, I struggle to bring an eyepiece to focus in essence killing my scope as a visual instrument.

If I were getting into astrophotography as a visual observer, I would buy the dob, do some visual and when I was ready to do some photography buy a small refractor and an EQ mount. The modifications that I have done to my newtonian cost more than an ED80 which is the beginer scope most people I have seen use for photography. Then you have the dob to look at stuff while you are taking photos.

[alistairsam]

Originally Posted by Aaron

Hi Everyone,

I'm looking at purchasing a 10" SW Dob for general viewing but I would like to eventually get into astrophotography. I've heard that the easiest way to do this without buying two scopes is to use your OTA off the dob and put this on a EQ mount.

Is this correct and would the OTA dob brackets get in the way on mounting it to a EQ mount?

Cheers,
Aaron

Hi Aaron,

it would depend on the brackets/ Dob supports on the OTA. Generally, as you'd use tube rings and a dovetail bar to attach to an EQ mount, you can rotate the OTA so the supports don't interfere.
here's an example I found using a SW OTA on a Dob and Eq mount.
http://www.marcthescopeguy.com/10inchrev.html
as you can see, the tube is rotated so the supports don't interfere.
so should be no issues if the one you're looking at is similar.
you would need to rotate it along the optical axis for balance.

As you would've read, a stable mount is extremely important with astro photography, so I'd suggest you do some research and look for reviews on the gear you're interested in for photography.
good luck.

[Tandum (Robin)]

I used an 8" SW dob on a heq5 with a canon 450D and 40D for quite a while and I had a 10" GSO dob on an eq6 with a mono ccd and filterwheel. I did change the focuser on the 8" to a low profile focuser to get focus, nothing else, although I think the default focusers are different now and changing them isn't as simple as it used to be. I put a moonlight on the 10" to carry the weight of the camera/wheel/filters and moved the primary mirror up the tube to gain focus with the ccd. I used an coma corrector on this scope. I've attached a pic of both setups and I think I can make out the holes from the dob mounts in both. There are bigger images in my gallery I think. The 10" on the EQ6 needed 4 counterweights which sort of indicates the mount is near it's limit, the mirrors in these things are very heavy.

[peter_4059 (Peter)]

I started with a 10" GSO dob and then bought an EQ6 for astrophotography. I've made a few changes including moving the mirror forward and changing the focuser however I can still put the ota back on the dob base for visual and achieve focus with both an eyepiece and camera.