Hi,

?

I'm looking to buy a mount that guide my reduced C8 (1450mm, 0.5"/px) at 0.37" rms or better.?

?

see this link for details:

203 mm aperture, 1450mm focal length, 1" seeing

?

Also, at some future point I want to buy a Stellarvue SVX152T and then I'd need to guide it at 0.4" rms or better.

?

Do people think these Losmandy mounts are capable of this performance on a regular basis?

I currently own an EQ6-R and it performs at about 0.38" - 0.48" rms on? a regular basis.? ?

?

If I can get that performance from an EQ6-R what performance would I get with a brand new Losmandy?

Thanks for and advice or help people can give.

On Thu, Nov 21, 2024 at 01:16 PM, <johnswanstone@...> wrote:

Hi,

?

I'm looking to buy a mount that guide my reduced C8 (1450mm, 0.5"/px) at 0.37" rms or better.?

?

see this link for details:

203 mm aperture, 1450mm focal length, 1" seeing

?

Also, at some future point I want to buy a Stellarvue SVX152T and then I'd need to guide it at 0.4" rms or better.

?

Do people think these Losmandy mounts are capable of this performance on a regular basis?

I currently own an EQ6-R and it performs at about 0.38" - 0.48" rms on? a regular basis.? ?

?

If I can get that performance from an EQ6-R what performance would I get with a brand new Losmandy?

Thanks for and advice or help people can give.

?

Yes Losmandy mounts can guide reliably under 0.5" RMS but unless you are imaging at 14,000 feet and have perfect conditions the mount regardless of brand will never be the imaging limitation due to the atmosphere getting in the way.??

?

?

?

--

I would not expect that level of accuracy on a naked mount unless you have a PEC loaded into the mount - maybe. ?One simply uses PemPro on a Windows PC to create that. ?

?Losmandy RA gear is the issue. ?Remember These are gear drives. ?You should plan on learning how to adjust that RA and the clutches for which adjustment can change significantly in cold weather. For example In the mountains the clutches can readily loosen if one sets up in the day at say 70 degrees and it cools to 35 at night which is common in Colorado summer nights high up; or in the Fall/Spring in American SouthWest conditions. Beware clutch adjustment can change on you. ?I commonly will tighten the clutches slightly with temp drops.

To really guide w/ that level of reliability and better, you would want to setup auto-guiding and still provide a PEC. ?I used a 420mm William optics OTA w/ Zwo 290m camera for guiding. ?Image scale ~ 1.4” image scale. ?I tried off-axis guiding and gave up. The C8 has lots of coma near the mirror edge.?

I’ve auto-guided both a FL 2023mm C8 and a FL 2000mm 10”RC on my G11. ?I would say auto-guiding is definitely required for astrophotography. ? Remember seeing conditions are highly variable and change throughout the night causing one’s guiding to vary widely. Also those OTAs are heavy. The C8 isn’t too bad, but w/ autoguiding, and the additional weights needed the unit can become sensitive to light breezes causing a wag. ?The Losmandy is strong but all that weight can react.?

I’ve commonly imaged at 10,000 seeing no difference in performance compared to imaging at 5,000’. ?I will utilize King’s Rate depending how low in the sky the target is, and that’s at 5,000’

To maintain better than 0.37” you’ll have to work at it and select nights based on seeing. I could certainly auto-guide at better than .4 on good nights, or parts of nights, ?but hit 1.0+” on poor nights or nights w/ a breeze. ? I would never say you’ll get better than .37” all the time. ?Of course with reduced FLs everything is easier. ?Note a refractor can wag in a breeze too.

The EQ6-R will be less of a headache, but the Losmandy will be stronger if you’re pushing the payload weight.

On Fri, Nov 22, 2024 at 01:11 PM, Mtn Goat wrote:

?

I would not expect that level of accuracy on a naked mount unless you have a PEC loaded into the mount - maybe. ?One simply uses PemPro on a Windows PC to create that. ?

?

?Losmandy RA gear is the issue. ?Remember These are gear drives. ?You should plan on learning how to adjust that RA and the clutches for which adjustment can change significantly in cold weather. For example In the mountains the clutches can readily loosen if one sets up in the day at say 70 degrees and it cools to 35 at night which is common in Colorado summer nights high up; or in the Fall/Spring in American SouthWest conditions. Beware clutch adjustment can change on you. ?I commonly will tighten the clutches slightly with temp drops.

?

To really guide w/ that level of reliability and better, you would want to setup auto-guiding and still provide a PEC. ?I used a 420mm William optics OTA w/ Zwo 290m camera for guiding. ?Image scale ~ 1.4” image scale. ?I tried off-axis guiding and gave up. The C8 has lots of coma near the mirror edge.?

?

I’ve auto-guided both a FL 2023mm C8 and a FL 2000mm 10”RC on my G11. ?I would say auto-guiding is definitely required for astrophotography. ? Remember seeing conditions are highly variable and change throughout the night causing one’s guiding to vary widely. Also those OTAs are heavy. The C8 isn’t too bad, but w/ autoguiding, and the additional weights needed the unit can become sensitive to light breezes causing a wag. ?The Losmandy is strong but all that weight can react.?

?

I’ve commonly imaged at 10,000 seeing no difference in performance compared to imaging at 5,000’. ?I will utilize King’s Rate depending how low in the sky the target is, and that’s at 5,000’

?

To maintain better than 0.37” you’ll have to work at it and select nights based on seeing. I could certainly auto-guide at better than .4 on good nights, or parts of nights, ?but hit 1.0+” on poor nights or nights w/ a breeze. ? I would never say you’ll get better than .37” all the time. ?Of course with reduced FLs everything is easier. ?Note a refractor can wag in a breeze too.

?

The EQ6-R will be less of a headache, but the Losmandy will be stronger if you’re pushing the payload weight.

?

On Nov 22, 2024, at 1:13?PM, Chip Louie via groups.io <chiplouie@...> wrote:

On Thu, Nov 21, 2024 at 01:16 PM, <johnswanstone@...> wrote:

Hi,

?

I'm looking to buy a mount that guide my reduced C8 (1450mm, 0.5"/px) at 0.37" rms or better.?

?

see this link for details:

203 mm aperture, 1450mm focal length, 1" seeing

?

Also, at some future point I want to buy a Stellarvue SVX152T and then I'd need to guide it at 0.4" rms or better.

?

Do people think these Losmandy mounts are capable of this performance on a regular basis?

I currently own an EQ6-R and it performs at about 0.38" - 0.48" rms on? a regular basis.? ?

?

If I can get that performance from an EQ6-R what performance would I get with a brand new Losmandy?

Thanks for and advice or help people can give.

?

Yes Losmandy mounts can guide reliably under 0.5" RMS but unless you are imaging at 14,000 feet and have perfect conditions the mount regardless of brand will never be the imaging limitation due to the atmosphere getting in the way.??

?

Remember that the atmosphere will also limit guiding accuracy just as it does imaging.? So guiding by its nature is always limited.?

?

?

--

Chip Louie Chief Daydreamer Imagination Hardware?

Astrospheric - South Pasadena, CA?

?

?

Never used PEC.? I and many pothers routinely auto guide under 0.5" on my 20+ year old but fully updated G11G2.? On a good night much lower and in the 0.3x" range.??

?

?

--

It sounds like you are looking for some unrealistic guarantee of guiding performance.

Here's my results: Yes, I can get into the low .30's and even into the high .20's.

The conditions depend (and vary a lot) on the object I'm imaging.

For example, the closer I am to the NCP I've gotten tighter guiding results.

Until now I considered lower guiding performance had to do with varying atmospheric conditions.

?

The are so many variables in this sport you cannot expect a given performance window consistently. It is unrealistic to do so.

You cannot blame your equipment for atmospheric conditions beyond anybody's control.

Losmandy states you should expect guiding at .50 or below. And that is what one can see, generally.

But no guarantee's.

?

In my experience, 90% of the bad reports around any Losmandy mount is a new owner "fiddling" with their mount, then blaming the mount for misbehaving. One bisquiethead took his all apart and put it back together while waiting for the obligatory bad weather to clear so he could take it outside and use it.

When I took delivery of my GM811G HD at Scotts factory in Burbank California, (Yes, I picked mine up at the factory) I was holding the box for the HD tripod while Scott himself was lowering the tripod into the box. (Too heavy for little Tanya to pack by herself)

He told me quietly, "Don't "mess" with it. Just use it." Sage advice.

Any adjustments I've done with mine were to the DEC worm and I wound up backing it off to nearly where it was to get my guiding back to great again. (I was reducing backlash that had developed over time.)

?

So no, no guarantees. But you can be assured that if you buy one of the Losmandy mounts it will be as finely tuned as possible right out of the box.

Which is a damn sight better than any Asian mount. Scott himself does the final assembly to his mounts.

Show me any other manufacturer who does such personalized service.

?

Maybe you can be more realistic.? I'm sure your EQ6-R did not get such care before it was shipped. So, stop pulling my leg.

--

Sonny Edmonds
GM811G HD