Telescope for deepsky!

On Friday, May 1, 2015 at 4:01:19 PM UTC-6, Uncarollo2 wrote:

Yes, refractors have pretty much taken over in deep sky wide field imaging.
They are easy to use, maintain collimation and produce superb results. Besides,
where is the average amateur going to get a Lurie Houghton? And Ritchie-
Chretien scopes are very expensive, difficult to make accurately, difficult to
collimate and are not the best choice for a reflective system any more.

Wide-field imaging - in other words, imaging at a low magnification, where
aperture is not a consideration - OK, I'll believe that.

I know that there are ads pitching Ritchey-Chretien systems at the deep-sky
astrophotographer - and so, basically, I was thinking in terms of things at
least _somewhat_ less expensive than a refractor that you could get with a
large aperture.

If I was going to give up some aperture, the next step down would have been one
of those modified Schmidt-Cassegrains like that introduced by Meade with a
larger central obstruction and freedom from coma.

But given the spectacular pictures from the Hubble, maybe not many people
bother with narrow-field deep-sky astrophotography.

John Savard

On Fri, 1 May 2015 15:49:31 -0700 (PDT), Quadibloc
wrote:

But given the spectacular pictures from the Hubble, maybe not many people
bother with narrow-field deep-sky astrophotography.

A lot of people like wide-field imaging. But not all. I have little
interest in it. I like small objects. For that, there are a number of
good optical designs- SCT, RC, DK, and others which offer excellent
optics as well as large apertures.

On Friday, 1 May 2015 21:12:29 UTC+2, Quadibloc wrote:

While some have said there's no simple answer, Dobsonian certainly comes close
to a simple answer for visual deep-sky observing.

If tracking is required then driven platforms are available and can be made to designs readily available online.
I wonder why amateurs don't dig out a sunken area for the platform or baseboard when they use larger/longer Dobsonians in the backyard at home.
This idea may not work well in swampy areas of Florida.
But it might save climbing a a couple of extra rungs on the stepladder in the dark.

On Saturday, May 2, 2015 at 1:48:52 AM UTC-4, Chris.B wrote:
On Friday, 1 May 2015 21:12:29 UTC+2, Quadibloc wrote:

While some have said there's no simple answer, Dobsonian certainly comes close
to a simple answer for visual deep-sky observing.

If tracking is required then driven platforms are available and can be made to designs readily available online.
I wonder why amateurs don't dig out a sunken area for the platform or baseboard when they use larger/longer Dobsonians in the backyard at home.
This idea may not work well in swampy areas of Florida.
But it might save climbing a a couple of extra rungs on the stepladder in the dark.

Few Dobs require a very tall ladder since the focal lengths are generally kept to well within 120 inches, even for "large" examples. The OP is probably not ready for such a scope anyway.

On Friday, May 1, 2015 at 10:48:52 PM UTC-7, Chris.B wrote:

I wonder why amateurs don't dig out a sunken area for the platform or baseboard when they use larger/longer Dobsonians in the backyard at home.

This is a poor idea for a few reasons. In order to look at an object that is, for example, at a 45-degree elevation, the diameter of the sunken area would need to be at least somewhat larger than the diameter of the telescope, or else the dob would not be able to decline enough to see the object. However, when looking at an object high in the sky, that sunken area would need to be very close to the size of the telescope because the ladder would necessarily need to be right next to it. This would work *only* for a large dob that was going to permanently be pointed close to the zenith.

Having a pit around a telescope, which is used in total darkness, is a bad idea in any case, and would be an accident just waiting to happen.

\Paul A

On Saturday, 2 May 2015 20:27:57 UTC+2, palsing wrote:

Having a pit around a telescope, which is used in total darkness, is a bad idea in any case, and would be an accident just waiting to happen.

Note that I said "a rung or two." Which might be critical to the choice of ladder or only a beer crate.
I was not talking about taking up mining nor excavating a leaky swimming pool.
So you can put down your picks, shovels and helmet lamps and send the guys home for a well-earned beer.
Those who complain about the extra height of a driven platform need look no further than a hole of suitable depth.
Made just large enough to allow clearance for its movement and any resetting.

On Friday, 1 May 2015 19:13:06 UTC-4, Chris L Peterson wrote:
On Fri, 1 May 2015 15:49:31 -0700 (PDT), Quadibloc
wrote:

But given the spectacular pictures from the Hubble, maybe not many people
bother with narrow-field deep-sky astrophotography.

A lot of people like wide-field imaging. But not all. I have little
interest in it. I like small objects. For that, there are a number of
good optical designs- SCT, RC, DK, and others which offer excellent
optics as well as large apertures.

The wide angle fetish is alive an well in the conventional photography world too. You'd think with the accuracy of guiding today, the quality of CMOS sensors, the shortness of exposures and the relative cheapness of large long focal-length scopes, you'd see more images of things like planetary nebulae, smaller galaxies, obscure distant star-clusters.

On Sun, 3 May 2015 16:52:34 -0700 (PDT), RichA
wrote:

The wide angle fetish is alive an well in the conventional photography world too. You'd think with the accuracy of guiding today, the quality of CMOS sensors, the shortness of exposures and the relative cheapness of large long focal-length scopes, you'd see more images of things like planetary nebulae, smaller galaxies, obscure distant star-clusters.

We do see many images made by amateurs that cover fairly narrow
fields.

On Sunday, May 3, 2015 at 12:49:31 PM UTC-4, Chris.B wrote:
On Saturday, 2 May 2015 20:27:57 UTC+2, palsing wrote:

Having a pit around a telescope, which is used in total darkness, is a bad idea in any case, and would be an accident just waiting to happen.

Note that I said "a rung or two." Which might be critical to the choice of ladder or only a beer crate.
I was not talking about taking up mining nor excavating a leaky swimming pool.
So you can put down your picks, shovels and helmet lamps and send the guys home for a well-earned beer.
Those who complain about the extra height of a driven platform need look no further than a hole of suitable depth.
Made just large enough to allow clearance for its movement and any resetting.

That was an incomplete sentence.

The ladder will tend to be dangerous only to those who climb it, whereas a pit or even a small excavation could be a hazard to everyone who ever ventures near it.

Digging holes and pits is also problematic when setting up at star parties or on paved or landscaped surfaces.

On Monday, May 4, 2015 at 5:58:36 AM UTC-7, wrote:

Digging holes and pits is also problematic when setting up at star parties or on paved or landscaped surfaces.

Chris B specifically said "I wonder why amateurs don't dig out a sunken area for the platform or baseboard when they use larger/longer Dobsonians in the backyard at home."

IN THE BACKYARD AT HOME!

Your reading comprehension skills, again, are found wanting...