Good Barlow for Imaging?

[davewaldo]

Hi Guys,

I was wondering which barlow I should purchase for photographic imaging. I'm soon buying an 80ED setup and was first considering the GSO 2" ED however I belive this is not such a great barlow. I was recomended the 2" Orion Deluxe. I have a $200AUS budget.

Do most people think that a 2" is better for photography than a standard 1.25?

Cheers

Dave

[iceman (Mike)]

Hi Dave!

to the forum!

What sort of imaging are you planning to do?
What camera/imaging device are you going to use?

[davewaldo]

I'm planning on doing general imaging... whatever I can get out of my scope and mount. I believe the 80ED is best suited to wide field images. I would also like to photograph the moon as close as possible.

I'm using a unmodified Canon 20D and a Sirius Mount. Wih Skywatcher ED80.

[janoskiss (Steve H)]

Dave!

I don't think you need a barlow for imaging with the ED80. It's a f/7.5. With a typical barlow it will be f/15 which is awful slow for all but the brightest targets. If you're thinking you want more magnification for planets, there is little point as the scope does not have the resolution for detailed planetary images anyway. On the Moon it might make sense to use a barlow. I have zero imaging experience btw.

[Dennis]

Hi Dave and welcome.

Very crudely, you will probably find that astro-imaging can be classified into a few major groups:

1. Individual DSO’s (Deep Sky Objects). e.g. galaxies, clusters, nebulae, etc. as the dominant subject matter.
2. Wide field. As above but in a wider field – a pretty setting where the object is generally not dominant (not including the large area nebulae, etc).
3. Lunar and Planetary (high resolution)
4. Lunar and Planetary (wider, pretty pictures).

The 80mm is probably more optimised for 2 and 4 which IMO do not require a barlow.

1 and 3 require more aperture.
1 requires a solid, accurate (= expensive) mount for tracking and auto-guiding purposes.

Based upon the above, I would probably not recommend spending money on a Barlow at this stage, as this places far too great a demand on the mount (long exposures required) and allied skills such as finding objects, focusing, etc.

Anyhow, that’s a brief brain dump to try and cover what I think may be some main topics for consideration.

Cheers

Dennis

[davewaldo]

I was also keen to buy a barlow as it would effectivly double my limited eyepiece collection. As well as using it for moon photography....

cheers.

[[1ponders] (Paul)]

Dave and welcome to the group.

If you are mobile and able to, we are having a dark sky night on the Sunshine Coast this Saturday night out near Kenilworth. We are hoping for good turnout and you would be more than welcome to turn up. Details here and a map here. I will be set up for imaging on the night so you will get an idea of what is needed for the different types of imaging.

[janoskiss (Steve H)]

Dave, the Orion Deluxe 2" is a fantastic barlow but I don't think it would be suitable for the ED80. It's very long and heavy, so might get awkward in a 2" diagonal. It also might have trouble reaching focus with many eyepieces (you'd really need to try it to check).

I do know the GSO 2" barlow does work with a 2" diag in the ED80. Apparently there is nothing between the standard and ED GSO 2" barlows, so maybe save a few bucks and buy the standard (so-called "achromatic") if you're going GSO. If you want a nice compact and versatile 2" barlow, the Antares 1.6x is very good. I bought it from ScopeStuff. But unless you have specific reason for wanting a 2" barlow, a 1.25" might be better choice: lighter and more convenient with 1.25" EPs.

[John K]

If after all your research you are still content on getting a Barlow, these guys are also excellent to deal with and their reputation in terms of quality is very goodas well.

http://www.siebertoptics.com/SiebertOptics-barlows.html

[Geoff45 (Geoff)]

I used a Bintel barlow (presumably GSO) the other night with a 110mm refractor at f7 and a televue 6mm radian eyepiece, giving a power of around 260. Jupiter looked pretty good, so I guess it was thumbs up for the barlow.
Geoff

[Striker (Tony)]

I wouldn't be buying a barlow for imaging with a 20D on the ED80....you may not be able to get focus.

If your intensions are for visual then it may be worth while going on what eyepieces you have.

[JohnG (John)]

Hi Dave

Might I add something to what has already been said. With your scope and camera, I would not even think of using 1 1/4 camera adapters etc. With the 20D you will get a huge amount of vignetting if you go along that route, make full use of the chip size and go 2".

I use an SW ED80 as my guidescope and have found that you need a tube extension to bring my autoguider to focus, I have attached my 350D as well and it also required a 50mm tube extender to bring it to focus, Bintel has these at a reasonable price.

I, personally, would not get a Barlow, in fact, I would more likely opt for a 0.8 reducer to give an even wider FOV and faster exposures.

The native f/7.5 of the ED80 has shown itself to be an awesome imaging scope with a huge number of excellent photo's being published so I would just use that to start on your astrophoto adventures, worry about a Barlow or Focal Reducer, later.

Cheers

JohnG