15 replies to this topic

[GOLGO13]

Hello. I recently got a 12 inch F4 dob. I had been using a 10 inch F4.7 before this.

 

Since the scope is pretty fast I'm going to need to use a Paracorr in general. I have an original Paracorr type 1.

 

Question for eyepieces. in general I'll be using a 24 panoptic, 18.2 delite, 13 Delite, 7mm nagler type 1, nagler 3-6 zoom. I have some old instructions that have the 24pan setting listed, but not sure on the others. I also don't have the TeleVue flat top 2 inch to 1.25 inch adapter that says it has 9.5mm that it adds. Mine looks to be very close...maybe 9mm.

 

Once I set one, I can try to adjust to the focus to find them. but I'm also unsure on the settings. One reason i question things a bit, when I used the 35mm Panoptic and focused, when I put the 24 pan in there was no adjusting to reach focus.

 

Let me know if there are any good tricks for this beyond winging it.

 

I may need to head toward the type 2, but I rather not if possible.

[dave brock]

I use a type 1 in my 20" f/4.5 dob. When the tunable top is up it's a bit wobbly so I use it lowered for all eyepieces. I'll probably get laughed at but it works fine for my eyes.

[mrowlands]

You should be ok with the Type 1 at F4.

 

On my instructions:

35mm Pan: Mark #1

24mm Pan: Mark #4

Nagler 3-6 zoom:  Not listed but I've always used Mark #4 since my Pan 24 and Nagler T6s all use that as well.

7mm Nagler T1:  Mark #4

Delites not listed on my chart.

 

If you're really near sighted and don't use your glasses when observing, you can run out of inward focus with the Pan 24.

 

If your tunable top is a little wobbly on the original Paracorr, you can put some tape strips under the moving barrel.  Ideally something like teflon tape but I've gotten by with Scotch tape!

 

Mike R.

[helpwanted]

With the type 1 & 2, the setting for all of TV 1.25” eyepieces is the same setting, with the only exception of the 17 & 14 Delos, which you didn’t mention in your post. 

[kathyastro]

If you have the setting for the Pan24, start with that one.  Set the tunable top for it, and focus it.  Then lock the focuser (or avoid moving in subsequent steps it if it doesn't have a lock).

 

For each eyepiece, insert it into the tunable top.  Then, without moving the focuser, adjust the tunable top to focus the image.  Note the position of the tunable top.  That is the correct position for that eyepiece.

 

Once you have noted the position for each eyepiece you own, you can set the correct position when you insert the eyepiece and use the regular focuser to focus the image.

[a__l]

GOLGO13, with P1 it's easier to remove the head and adjust NV in prime focus than with P2.

You are not using Ethos-21, which is problematic for P1. All your eyepieces will work well with the P1. Therefore, it makes no sense to replace it with P2 for your telescope.

Edited by a__l, 27 November 2022 - 04:32 PM.

[areyoukiddingme]

21 Ethos and 31 Nagler do not have optimal correction in the P1--they need more in-focus. 

 

In practice, I can't see any issues.

[a__l]

E21 has a longer skirt than N31 and therefore does not fit into P1 (in depth). With the same distance F. https://www.televue....page.asp?id=214
N31 coexisted with P1 for quite some time.

[Jon Isaacs]

 

Once I set one, I can try to adjust to the focus to find them. but I'm also unsure on the settings. One reason i question things a bit, when I used the 35mm Panoptic and focused, when I put the 24 pan in there was no adjusting to reach focus.

That is perplexing.  If you had the original photo-visual Paracorr which did not have a Tunable Top and the correct 2" to 1.25" adapter, then the 24 mm Panoptic and the 35 mm Panoptic would require very little focusing.

 

I think the Type 1 is very workable at F/4 but there are two reasons to upgrade to the Paracorr 2:

 

- The Type 2 Tunable Top is much better. It's smooth and can be used as a focuser. With the Type 1 Tunable Top, it was best to move the top and then insert a heavier eyepiece, that's not necessary. I believe the last run f the Type 1's had this same top.

 

- Better coma correction. At F/4, the entire field (46mm) of any inch eyepiece is fully corrected. With the Paracorr 1, it's less than 10 mm.

 

 

Jon

[GOLGO13]

That is perplexing. If you had the original photo-visual Paracorr which did not have a Tunable Top and the correct 2" to 1.25" adapter, then the 24 mm Panoptic and the 35 mm Panoptic would require very little focusing.

I think the Type 1 is very workable at F/4 but there are two reasons to upgrade to the Paracorr 2:

- The Type 2 Tunable Top is much better. It's smooth and can be used as a focuser. With the Type 1 Tunable Top, it was best to move the top and then insert a heavier eyepiece, that's not necessary. I believe the last run f the Type 1's had this same top.

- Better coma correction. At F/4, the entire field (46mm) of any inch eyepiece is fully corrected. With the Paracorr 1, it's less than 10 mm.



Jon

I agree Jon. Only potential thing I was thinking was my 2 inch to 1.25 inch adapter isn't original. But it's also a flat top and appears to be 9mm vice 9.5mm. I'll keep checking though.

[a__l]

In fact, these charts show incomplete information. Only coma. It would be correct to indicate the spots. This information is not available from TV. Therefore, to argue how much better P2 is from P1 at f/4 can only be based on ATM observation, which may not be true.

 

A definite plus of the P1 head is that it can be easily removed. Which might matter to the OP. Because NV is one of his tools.

Edited by a__l, 29 November 2022 - 06:22 PM.

[GOLGO13]

In fact, these charts show incomplete information. Only to coma. It would be correct to indicate the spots. This information is not available from TV. Therefore, to argue how much better P2 is from P1 at f/4 can only be based on ATM observation, which may not be true.

A definite plus of the P1 head is that it can be easily removed. Which might matter to the OP. Because NV is one of his tools.

Also tight on cash lately, so the T1 should be good enough. I'll have to figure out the spacing for night vision

[a__l]

With NV two nuances.
The power knob can get in the way.
The uncertainty with the glass thickness of the NV sensor.

[Starman1]

You should be ok with the Type 1 at F4.

 

On my instructions:

35mm Pan: Mark #1

24mm Pan: Mark #4

Nagler 3-6 zoom:  Not listed but I've always used Mark #4 since my Pan 24 and Nagler T6s all use that as well.

7mm Nagler T1:  Mark #4

Delites not listed on my chart.

 

If you're really near sighted and don't use your glasses when observing, you can run out of inward focus with the Pan 24.

 

If your tunable top is a little wobbly on the original Paracorr, you can put some tape strips under the moving barrel.  Ideally something like teflon tape but I've gotten by with Scotch tape!

 

Mike R.

Note: Setting 1 is with the top raised all the way.  Setting 5 is with the top lowered all the way.

[Starman1]

21 Ethos and 31 Nagler do not have optimal correction in the P1--they need more in-focus. 

 

In practice, I can't see any issues.

Just use setting 5 (lowered all the way) and refocus the scope.  You're only talking a few mm here, not enough to destroy coma correction, even if not 100% optimum.

But after using one of those, do not find the setting for another eyepiece using the focuser position, but re-set the Paracorr using an eyepiece that uses a higher setting.

[rjacks]

If you have the setting for the Pan24, start with that one.  Set the tunable top for it, and focus it.  Then lock the focuser (or avoid moving in subsequent steps it if it doesn't have a lock).

 

For each eyepiece, insert it into the tunable top.  Then, without moving the focuser, adjust the tunable top to focus the image.  Note the position of the tunable top.  That is the correct position for that eyepiece.

 

Once you have noted the position for each eyepiece you own, you can set the correct position when you insert the eyepiece and use the regular focuser to focus the image.

Yes, if you know the setting for one eyepiece that you have, you can figure it out for any eyepiece by this technique.