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List of Paracorr settings for all brands of EP's

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#101 deSitter

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Posted 13 August 2009 - 09:13 AM

Here's a handy (for me at least) Paracorr trick - defocus so that the shadow of the secondary is clearly visible but not too large - and tune the Paracorr so that the pattern is symmetrical in the out-of-focus center stars as well as the out-of-focus edge stars. Coma will make a lopsided pattern with the shadow close to the inner edge.

-drl
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#102 JoshH

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Posted 21 October 2009 - 10:18 AM

Anyone have any suggestions for the proper setting on the University Optics 40mm MK-70? I tried this eyepiece for the fist time in my 16" F4.5 dob along with the Paracorr and I was quite happy with the performance. There was still some coma present, but it made a totally un-usable eyepiece in my dob into an eyepiece I will probably use often. The sky background was a bit too gray for my liking in what I would call pretty good skies, but it made a nice view for large objects like the double cluster as it gave a 1.3 deg FOV. The exit pupil is a bit large but I never saw the shadow from the secondary. I found that position 2 seemed to give the best view, any other comments?

#103 Brian Schmidt

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Posted 07 February 2010 - 10:21 AM

Hi guys,
I just figured something out with the 9 T1 Nagler, and presumably the older 8.8 and 14 uwa eyepieces. Previously I was unable to achieve the best correction using my 9 T1 Nagler in either 1.25 or 2 inch mode. The problem with the 9 T1 is that the it sits down too far in 2 inch mode and up to far in 1.25 inch mode. So, I just bought some 2 inch "parfocaling" rings from scopestuff and put one on my 9 T1 just below the safety undercut. Works perfect on setting 1 along with my 35 and 22 pans. :grin:

#104 rockethead26

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Posted 07 February 2010 - 01:13 PM

Thanks Brian, thats a good tip. I have the 9 Nagler T1 and just bought the Paracorr. You saved me some grief when my new scope shows up in April.

#105 DietmarS

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Posted 09 June 2010 - 07:13 AM

http://www.cloudynig...&Number=3731894

In this thread you will read, that the 21mm Ethos sits about 4mm high on the shoulder of the Paracorr (new or old!).

How can you use parfocalized eyepieces with this?

You would need to have additional 4mm rings to parfocalize for Paracorr use :question:

#106 Starman1

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Posted 09 June 2010 - 12:24 PM

Here's a handy (for me at least) Paracorr trick - defocus so that the shadow of the secondary is clearly visible but not too large - and tune the Paracorr so that the pattern is symmetrical in the out-of-focus center stars as well as the out-of-focus edge stars. Coma will make a lopsided pattern with the shadow close to the inner edge.

-drl

Yes.
A defocused star at the edge of the field will not have the shadow centered, but the outer bright pattern in the star should still be round and not oblong.
I used your technique to adjust my 13 Ethos and ended up with the same setting accomplished by looking at the infocus images.
However, your technique doesn't require good seeing.

#107 roamer

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Posted 13 June 2010 - 07:22 PM

One "relatively" safe means to measure the insertion depth of a late model Visual Paracorr while at its lowest height setting on the tunable top would be to simply place a cotton 'Q'-tip down the side until it rests by gravity on the lens element, and then mark it at the shoulder junction. Then remove it, and stand it up (without any downward force applied), and measure from the table top to the mark on the 'Q'-tip.

CAUTION / WARNING: Again, I warn that I would not wish or intend that anyone scratch a Paracorr in attempting to measure it.


Dang. I must be reading your mind. I did that yesterday to see if an eyepiece would fit and it did.

To anyone: I mainly have a mix of Meade, Televue and Orion Plossl's. Only 2" eyepieces are a MeadeQX 26mm and an Explore Scientific 19mm. I am going to read the Paracorr doco literally and set it to 4 for the plossl's as it say setting 4 for all Plossl's up to 32mm. The 2" eyepieces I am going to have to experiment.

#108 rockethead26

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Posted 05 July 2010 - 11:07 AM

My 28 UWAN works best at setting #3.

#109 Tim A.

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Posted 11 November 2010 - 02:27 AM

Here's a handy (for me at least) Paracorr trick - defocus so that the shadow of the secondary is clearly visible but not too large - and tune the Paracorr so that the pattern is symmetrical in the out-of-focus center stars as well as the out-of-focus edge stars. Coma will make a lopsided pattern with the shadow close to the inner edge.

Brilliant!

#110 sixela

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Posted 28 December 2010 - 09:03 AM

Now your eyepiece's focal plane is low in the eyepiece, you will have to move the eyepiece back relative to the Paracorr's lens in order to maintain the correct distance to the lens for best correction. But that means the focal plane of the system is now higher than before.

Ideally it means it's at the exact same spot despite the different tunable top position.

With ideal positioning, the system focal plane is always at a fixed position with respect to the original focal plane. All the tunable top does is ensure the eyepiece focal plane can be moved there.

The only eyepieces for which in-focus or out-focus is required are those for which the tunable top range is insufficient. So I'm not disagreeing with your post (there are indeed eyepieces like that) but I think I do have to point out that any focuser in- or out-travel is not necessary for most eyepieces (those that have an ideal tunable top position within the real range allowed).

Your own recipe for finding the tunable top position confirms this: once you've set the focuser to the ideal position using a TeleVue eyepiece and the correct tunable top setting, you adjust only the tunable top to find the correct setting for the other eyepieces and you leave the main focuser alone.


So, eyepieces with low focal planes require more out travel with the Paracorr and more inward movement of the focuser.

Not unless the focal plane would force an "ideal" setting for the tunable top to be outside the real range.

Consider how the SIPS type 2 Paracorr for the Feathertouch focuser works: it always sits at one spot and you only tune it again if you move the focal plane of the scope (e.g. If you move the primary on its collimation bolts).

Buy the "tunable top" version of that same type 2 Paracorr and set the top correctly, and the lenses will end up at exactly the same position as those from the SIPS version, which entails that the focuser is always racked in the same way. QED.

Note that the SIPS plus Feathertouch focuser leaves only a couple of millimeters when you set it correctly and then focus a 21mm Ethos or 31T5. Fortunately, there are few eyepieces in 2" format that require more in-travel than those, but I have some 1.25" eyepieces that have the focal plane also on the eye side of the shoulder, and some do run out of focuser in-travel unless I use my Borg 1mm profile 2"-1.25" adapter.

#111 erick

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Posted 02 February 2011 - 06:57 PM

Can anyone advise the setting for the ES 14mm 100 deg?

#112 Sarkikos

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Posted 12 February 2011 - 07:55 PM

After reading this thread, I'm glad I bought a couple TV 25mm Plossls for my binoviewer. I can use one to set my Paracorr correctly. (All the TV Plossls through 32mm have a setting of 4, according to the Televue website.) Then it will be easy to set the Paracorr correctly for my other eyepieces. IMO, any other method seems to be more trouble than it's worth.

My advise is to buy a TV Plossl, the least expensive of the Televue eyepieces. They're even on sale now, or you can get one used. Then you can set your Paracorr and not have to deal with spreadsheets, measure the field stop distance, worry about the height of your 1.25"-2" adapter, or decide whether you can trust the setting advice that someone else gives you.

Get yourself a TV Plossl. :grin:

Mike

#113 star drop

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Posted 28 March 2011 - 09:57 AM

Explore Scientific 100° eyepiece settings in an adjustable top Paracorr type 1 are:
9 mm setting 1.6
14 mm setting 1.7
20 mm setting 5+ (beyond the range of travel)



#114 Sarkikos

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Posted 28 March 2011 - 10:19 AM

Thanks, Ted!

I haven't had a chance to take out my scopes for quite awhile. I also have the Paracorr Type 1 with Tunable Top, and both the ES 100deg 9mm and ES 100deg 14mm. Your information will come in handy for me. I was afraid that one or both would not come to optimum correction with the Paracorr Type 1, so this is welcome news.

How did you determine the settings? Did you prime the Paracorr with one of your TV eyepieces?

Mike

#115 star drop

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Posted 28 March 2011 - 10:28 AM

Hi Mike,

We primed the Paracorr with my friends 35mm Panoptic eyepiece. Soon I hope to start a new thread about my experience with coma.

#116 Sarkikos

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Posted 28 March 2011 - 10:42 AM

Very good. As time permits, I'd like to determine the settings for all of my non-TV eyepieces. I'll immediately plug them into my eyepiece spreadsheet, and eventually post them on CN. Not that everyone would be interested in the Paracorr settings for some of my oddball eyepieces, but it is what it is. I'm really surprised this information is not out there somewhere. I certainly haven't been able to find it.

Mike

#117 thewheel

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Posted 31 March 2011 - 03:20 PM

Hi,
I primed with 11mm TV Plossl and got this:

TV Tunable Top Type 1

Mark Eyepiece
5 = 4.7ES82
4.5 = 6.7ES82
1.75= 9ES100
2.5 = 14ES100
2.75= 28SWA these are the Series 5000 Meade
3 = 34SWA
3 = 40SWA

a little different don't know why , again primed 11mm TVPlossl

#118 Sarkikos

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Posted 31 March 2011 - 03:56 PM

Thanks. Yes, your settings and Star Drops differ a bit. I don't know exactly why they should vary. But both of these eyepieces seem to have a setting around 2. Maybe the fractional differences don't really make that much of a difference. A distinction without a difference?

9ES100: Star Drop 2, thewheel 1.75
14ES100: Star Drop 2 (1.75), thewheel 2.5

I'm curious to see the values I get when I have a break in the weather here.

Mike

#119 star drop

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Posted 31 March 2011 - 07:43 PM

Might the variation be due to Televue's rounding out of their prescribed settings? We each primed with different Televue eyepieces.

#120 Sarkikos

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Posted 31 March 2011 - 10:37 PM

That's a possibility. Televue always lists the settings as whole numbers. The way I understand it, the setting is dependent on the offset between the Paracorr lens assembly and the eyepiece's field stop, which should always be 55mm. Would that distance always be exactly at one of the Tunable Top settings? Unlikely.

Also, is the field stop of every TV Plossl, or every Radian, for instance, always at the exact same distance below the shoulder of the eyepiece barrel as the other eyepieces in that series? If they're supposed to be parfocal, I guess that could be true.

Mike

#121 star drop

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Posted 12 April 2011 - 12:34 AM

Priming a type 1 Paracorr with a 35mm Panoptic the setting for: 30mm Meade UWA is 1.5

#122 star drop

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Posted 26 April 2011 - 08:39 AM

Perhaps this information from the Televue eyepiece specifications page is relevant.

Panoptic field stops with respect to reference surface:

41mm .27
35mm .17
27mm .29
24mm .25
19mm .25

Plossl field stops with respect to reference surface:

8mm through 32mm .25

The 35mm Panoptic's value is the farthest from the approximate average value of around .25 and so it might not be the optimum eyepiece to use as a primer. If one takes my value for the 14mm ES 100 and multiplies it by .25/.17 the resulting value is very close to the value arrived upon by thewheel.
1.75 x .25/.17 = 2.57
If I ever get another clear night I will try priming the Paracorr with a few other Televue eyepieces.

#123 faackanders2

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Posted 01 May 2011 - 11:27 AM

Is there a list of Parracorr Type 2 Eyepiece settings for NON-Televue eyepiecs. I don't use my Parracorr as much as I should because I don't have the time to figure out all the settings for each eyepiece.

The only Televue eyepieces I hae are 10mm Ethos (at top most setting), 3.7mm Ethos (also top most setting), and 24mm Panoptic (uses only for binoviewing w/o Parracorr).

Currently the single eyepiece I use most is the Explore Scientific 20mm 100 AFOV at setting C.

#124 Starman1

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Posted 01 May 2011 - 12:48 PM

Is there a list of Parracorr Type 2 Eyepiece settings for NON-Televue eyepiecs. I don't use my Parracorr as much as I should because I don't have the time to figure out all the settings for each eyepiece.

The only Televue eyepieces I hae are 10mm Ethos (at top most setting), 3.7mm Ethos (also top most setting), and 24mm Panoptic (uses only for binoviewing w/o Parracorr).

Currently the single eyepiece I use most is the Explore Scientific 20mm 100 AFOV at setting C.


Put the 10 Ethos in at setting A (highest setting). Focus.
Insert the 20 ES and focus using the tunable top, not the focuser knob. Mark down the setting of the Paracorr. That will be the setting you tune to before you insert the 20 ES the next time.

You only focus using the tunable top to find the proper setting for the non-TeleVue eyepiece. In the future, you set the tunable top to the correct setting, insert the eyepiece and focus using the focuser.

In this same way, you can find the correct settings for an entire collection. Note that some 2"/1.25" hybrid eyepieces can not be optimized unless used in the 1.25" adapter: Ethos 8, Ethos 6, and others.

#125 bgavin

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Posted 01 May 2011 - 03:01 PM

Don, I was thinking about this process.

Does this take into account the varying amount of in-focus required between dissimilar EPs?

I have the Type 2, not used it yet.
I figure I can calibrate it with either the Radian 14, or the Panoptic 27.

It just seems to me that an EP with a different point of focus would require prime focus set first, then coma adjustment with the tunable top.

Or... I'm not yet understanding how it works.. :shrug:


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