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4.7 Vrs 4.5

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#1 patindaytona

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Posted 19 August 2019 - 06:58 PM

I just now noticed that the new xt10i is nearly a foot or so taller. Same size mirrors. Other is Coulter. The Coulter is alot "fatter" too.  I had to double check and see if the guy who sold it to me made a mistake for a 12"! As far as the ability to observe planets, is their a significant difference using the XT 4.7?

Maybe i should just keep my F7 8" for the planets.



#2 MitchAlsup

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Posted 19 August 2019 - 08:14 PM

You seem to be a product of the texas school system.

I just now noticed that the new xt10i is nearly a foot or so taller. 

Foot taller than what?

 

Other is Coulter.

 

Coulter what?

 

The Coulter is alot "fatter" too. 

In what way?

 

I had to double check and see if the guy who sold it to me made a mistake for a 12"

XT10 or XT12 or Coulter?

 

As far as the ability to observe planets, is their a significant difference using the XT 4.7?

Given equally well done mirrors, there is negligible difference in planetary observations between F/2.75 and F/25 (yes F/25). F/ratio does not matter, quality of the surface matters. And faster than F/5 the correction of the eyepieces matter.

 

{Forming quality sentences will help you get the answers you desire at a faster rate.}


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#3 stargazer193857

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Posted 20 August 2019 - 01:21 AM

I doubt you will notice much difference between f4.5 and f4.7.

There are many variables here:
The fatter scope may have a 1" gap instead of 1/2" gap, which is better for keeping tube thermals out of the light path.

Is the Coulter mirror 1" thick? Might cool faster.

You have 6 mirrors you mentioned, each mounted seperately. I bet you will need to aim and see to know.

8" f7 will be sharper at the edge and less detail in the middle, unless the collimation is off. The 4.7 is more picky.

The Coulter may have the largest secondary, though I would not worry about that.

The cardboard likely gives off less thermals at first but continues to give them longer perhaps. Watch and see.

The taller scope will be further up out of the ground thermals, which is important on summer pavement.

One might slew better or focus smoother than another. Maybe you don't want to sit as low for one.

Modern 10" scopes mount their OTA higher so people are seated higher. You can also store eyepieces underneath.

#4 Jon Isaacs

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Posted 20 August 2019 - 05:18 AM

Your best planetary scope is the one that gives you the best views.  No way to know that until you spend some time at that eyepiece.  

 

That said, Coulter Dobs were not known for their high quality optics.

 

Jon



#5 patindaytona

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Posted 20 August 2019 - 06:37 AM

You seem to be a product of the texas school system.

Foot taller than what?

 

Coulter what?

 

In what way?

 

XT10 or XT12 or Coulter?

 

Given equally well done mirrors, there is negligible difference in planetary observations between F/2.75 and F/25 (yes F/25). F/ratio does not matter, quality of the surface matters. And faster than F/5 the correction of the eyepieces matter.

 

{Forming quality sentences will help you get the answers you desire at a faster rate.}

Foot taller than the Coulter. Coulter 10" dob. Width. The Coulter (because it's much wider).



#6 patindaytona

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Posted 20 August 2019 - 06:40 AM

I doubt you will notice much difference between f4.5 and f4.7.

There are many variables here:
The fatter scope may have a 1" gap instead of 1/2" gap, which is better for keeping tube thermals out of the light path.

Is the Coulter mirror 1" thick? Might cool faster.

You have 6 mirrors you mentioned, each mounted seperately. I bet you will need to aim and see to know.

8" f7 will be sharper at the edge and less detail in the middle, unless the collimation is off. The 4.7 is more picky.

The Coulter may have the largest secondary, though I would not worry about that.

The cardboard likely gives off less thermals at first but continues to give them longer perhaps. Watch and see.

The taller scope will be further up out of the ground thermals, which is important on summer pavement.

One might slew better or focus smoother than another. Maybe you don't want to sit as low for one.

Modern 10" scopes mount their OTA higher so people are seated higher. You can also store eyepieces underneath.

I don't know if it's 1" thick or not Stargazer. I'm sure the xt10i is way way better than the Coulter.



#7 patindaytona

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Posted 20 August 2019 - 06:42 AM

One thing that i find very awkward with the xt10i is that i have to continually use the telrad on the right side, then run to the left side of the telescope to use the eye piece (same with using the intelliscope, continually exhanging sides of the telescope. I'm left handed and it feels very awkward to me to view from that side. When i use the telrad, it's like using a rifle scope....with my right hand to shoot. I can't do it that way.



#8 N3p

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Posted 20 August 2019 - 11:29 AM

One thing that i find very awkward with the xt10i is that i have to continually use the telrad on the right side, then run to the left side of the telescope to use the eye piece (same with using the intelliscope, continually exhanging sides of the telescope. I'm left handed and it feels very awkward to me to view from that side. When i use the telrad, it's like using a rifle scope....with my right hand to shoot. I can't do it that way.

You are not supposed to change sides? You should show us your telrad installation with a picture.

 

***

 

For the sake of the discussion only, one additional option. It's also possible to install a Rigel finder between the focuser and the existing Synta mount,  you can do that with the Rigel because it's small. Result is effective, Rigel is close to the focuser and it looks great

 

22pHF8d.jpg?2

 

I don't know which finder came with your telescope but if it's a right angle type (or even straight through) it can be combined with the Rigel so you can get a finder with no power, the Rigel, to roughly browse around and then you can use the right angle to deeply scan the sector with 50mm of aperture and something like 9x of power. I think it's very important in my opinion.

 

Either way, a dual setup, Rigel or Telrad with a finder with magnification, is a strong bet.

 

Rigel:

https://agenaastro.c...quikfinder.html

 

Right angle corrected image

https://agenaastro.c...age-finder.html


Edited by N3p, 20 August 2019 - 11:30 AM.


#9 patindaytona

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Posted 20 August 2019 - 12:24 PM

I can understand that Viking. The telrad i have fits into the dovetail slider where the original finder goes. (it has a fitting on it for that).

I could add the telrad to the side, but i don't want to stick it because of consequences later if i ever decided to try and take off the adhesive.

From opinions gathered, it seems that the telerad would be the choice if i had to choose just one over the other.

So, I'm hoping you know where the telrad location is since it's on the xt10i.

Just feels really awkward to me to view thru it from the eye piece side of the scope. Alot!




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