OTA upgrade?

[malau]

Hi all,

I have a Skywatcher 150/750 F/5 for astrophotography. Should I upgrade my tube? If so, my budget is around not more than 900 and seems not many options are there...

[pluto]

I used to use a SW 120 f5 for narrowband imaging and it was excellent bang-for-buck. However I never tried DSLR or LRGB imaging with it as, being an achro, I'm pretty sure you'd get a bit of false colour.

There are plenty of choices I think around $900 though - ED80, 10" newt, RC8, and probably many others...

[cometcatcher]

For what purpose to you wish to upgrade? What is the weakness of your present system?

This is the Newtonian on an EQ3 from memory. Your first point of upgrade should be the mount.

[malau]

Thanks everyone.

One of the reasons is I want to take the object looks larger and more detail. Or should I get 2x barlow with my TRing to do the job?

[cometcatcher]

What sort of objects? Planets or nebula and galaxies?

[malau]

Im more interested in Nebula and Galaxies.

I have unmod 600D btw... and a webcam for planets

[cometcatcher]

Okay thanks. So you want to photograph deep sky with what you have, and as I remember, you had a photo of the Leo triplet of galaxies. The 150mm F5 OTA is potentially a powerful telescope. No need to upgrade the OTA in my opinion. I have a 150mm F5. It's very good for deep sky.

Your EQ3 mount, well that's the weak point. For the 150mm F5 OTA, you can get great pics if you can get at least 15 - 30+ seconds without trailing. I don't think the standard EQ3 has a guide port, so that leaves you with two options. Unguided and manual guiding. For manual guiding you would need a guidescope, mounting brackets and an illuminated reticle eyepiece, oh and your eye. ;) The idea with manual guiding is to be able to expose longer before the stars trail by making small corrections with your hand controller. You line up your main 150mm scope, then you find a guide star in the guidescope and place the guide star in the middle of the reticle. With practice, careful guiding and good polar alignment, you may be able to expose for several minutes.

Unguided, well you've already seen how quickly the stars can trail. Which ever method you use, very accurate polar alignment is a must for astrophotography. You may have the best mount in the world, but if it's not well polar aligned it's useless.

Head over to the beginners astrophotography forum and see what they are able to achieve with modest equipment.

[malau]

Cool. Thanks. Atm with drive motor I can expose 25 sec. However in anytime only about 1/3-1/2 worth of photos can be use without trailing..etc (well.. including strong wind and clouds). If I upgrade the mount to say EQ5 I guess I have to also purchase autoguider right?

[cometcatcher]

I can't image in strong wind and clouds either and I have a HEQ5. With strong wind, I take off the 150mm OTA and put something lighter on like an ED80.

Have you thought about getting an ED80 refractor? Second hand they are $350 - 500. Still lots of things you can image and the EQ3 won't be so heavily loaded, so not as affected by wind etc.

[pluto]

If you're going to get into imaging you'd be much better off getting an HEQ5 not an EQ5. I started with an EQ5 and very quickly got frustrated with it when imaging, especially when I started guiding.
If your budget is limited just concentrate on the mount and don't worry about guiding for the time being, however if you want to take exposures longer than about 60 seconds you'll need an autoguiding setup

Just my two cents...