Paracorr questions

[bomberbaz]

Just wondering from anyone who has owned both or just who knows the difference between the type I and type II.  

I note from the televue website that the type II has a 1.15 barlow effect to push out the focus but cannot find any info on the type I ref this.

Is the focus push out on the type one and two the same.

which gives the better control on coma. One would assume its the II.

I am not rushng out to buy one (heard this before) but one never knows.

Steve

[estwing]

the only difference I read was that the mk1 wasn't designed with the ethos range in mind that's why I went for the mk2, both do the same job of cleaning up the coma...if your feeling flush you could just go for this system...http://www.starlightinstruments.com/

[Daniel-K]

get the ES one its miles easier to use. set it once for the night. 

[alan potts]

Steve I wrote a review on both last year, it is in Members equipment somewhere, about 6 months or back.

Alan

[YKSE]

Steve,

There seem to be a number of different Paracorr I, you can find out a bit more here

http://www.cloudynights.com/topic/444841-confused-different-models-of-paracorr-1/?hl=%2Bdifferent+%2Bparacorr#entry6986374

[bomberbaz]

8 hours ago, Daniel-K said:

get the ES one its miles easier to use. set it once for the night. 

just had a quick buchers at this and looks impressive but a good deal less than a PCorr. need to look inti this in more detail but i might treat myself when i sell the sw 12" goto.

cheers dan

[John]

Doesn't the ES one need quite a lot of inwards focuser travel - around 38mm I read somewhere ?

If you have this then it's worth considering.

 

[Scooot]

19 minutes ago, bomberbaz said:

just had a quick buchers at this and looks impressive but a good deal less than a PCorr. need to look inti this in more detail but i might treat myself when i sell the sw 12" goto.

cheers dan

I was curious about this as well after Dan's post so had a read about it. I don't quite understand how you can use different eyepieces without adjusting the spacing but if you can it looks very interesting.

[Daniel-K]

my mate who i sold my 14" to with a moonlight focuser on has no issues with inwards focus and it has two riser plates on.  honestly when i used it with the 30mm ES on the moon to test how well it corrected against my SIPS i was shocked at how sharp it was on the edges.  the craters on the moon when pushed to the edges of the EP where as sharp as in the middle . these are underrated.  steve its shame your not coming to SGL i have all my mates gear in my shed , i could have brought it for you to try.

[Thonolan]

4 hours ago, John said:

Doesn't the ES one need quite a lot of inwards focuser travel - around 38mm I read somewhere ?

If you have this then it's worth considering.

 

That's right. For me that's ideal as my Skywatcher 10" dobsonian needs extension tubes for every eyepiece. Having the ES coma corrector I don't need them anymore - in fact there's still about 30 mm of spare in travel with the corrector attached. And it's a quality product. I couldn't be happier with it.

Mine lives in the focuser so feel free to ask any question about it. There aren't many reviews of it as far as I know. Maybe I should write mine some day.

[Scooot]

19 minutes ago, Thonolan said:

That's right. For me that's ideal as my Skywatcher 10" dobsonian needs extension tubes for every eyepiece. Having the ES coma corrector I don't need them anymore - in fact there's still about 30 mm of spare in travel with the corrector attached. And it's a quality product. I couldn't be happier with it.

Mine lives in the focuser so feel free to ask any question about it. There aren't many reviews of it as far as I know. Maybe I should write mine some day.

Hi, so can you use different eyepieces without having to adjust the spacing. In other words do you just refocus and the corrector works just as well with each eyepiece? I must admit I would prefer a corrector that didn't need the tuneable top of the paracorr .

[Peter Drew]

I've just been trying out a type1 Paracorr on a 20" F3.5 Dob, used in conjunction with a 19mm Luminos eyepiece which just permitted a full lunar image, the craters were in sharp focus from edge to edge. Impressed!.

[Thonolan]

38 minutes ago, Scooot said:

Hi, so can you use different eyepieces without having to adjust the spacing. In other words do you just refocus and the corrector works just as well with each eyepiece? I must admit I would prefer a corrector that didn't need the tuneable top of the paracorr .

No, it doesn't work like that. You need different settings for each eyepiece (unless they're parfocal of course).

It's very easy to use, even in the dark, because I use the helical top as focuser. Imagine you have a certain eyepiece in the corrector, of course correctly focused and with the proper corrector setting. Whenever you insert a different eyepiece, turn the helical top up or down until that new eyepiece is focused as well. That's the correct setting for it. I don't touch the focuser at all unless I want some very fine focusing that involves less than, say, 1 or 2 mm focuser movement. Please note that corrector settings would be wrong for subsequent non parfocal eyepieces if you use the focuser instead of the helicap top of the coma corrector.

So you only need to know the correct setting for one eyepiece.

And if you don't even know the correct setting for one eyepiece there's a way to figure it out. Screw out the helical until the lower part of it it's 13.5 mm above the lowest possible setting as showed on this picture:

This way, the focus of the optical system will be exactly on the top end of the helical. I put a piece of translucent tape on the top end, and then, looking at a very bright object with the scope (I used Sirius, but it can be a bright planet or the Moon), I focus it with the scope's focuser on the "screen" created by the tape. The helical should be still at the 13.5 mm mark.

Now, if you knew the exact position of the field stop of your eyepieces, without touching the scope's focuser at all, you'd have to screw the helical in or out until the focus is exactly where the field stop is. So, for instance, if the field stop of an eyepiece is exactly where the body of a 2" EP meets the barrel you wouldn't need to touch anything. But that's not always the case. For instance, I need to screw my ES100 20mm in about 10 mm from that position (so the correct setting is 3-4 mm above the zero point of the scale) until it's in focus. That means the field stop of this eyepiece is 10 mm above the point where the EP's body meets the 2 inches barrel.

This may seem difficult or tedious but remember you only need to do it once. And believe me, once in the correct setting I can't see the slightest hint of coma in any of my eyepieces.

Hope it is clear enough. It's not easy to explain something like this when you're not using your native language.

Edited February 18, 2016 by Thonolan

[Scooot]

29 minutes ago, Thonolan said:

No, it doesn't work like that. You need different settings for each eyepiece (unless they're parfocal of course).

It's very easy to use, even in the dark, because I use the helical top as focuser. Imagine you have a certain eyepiece in the corrector, of course correctly focused and with the proper corrector setting. Whenever you insert a different eyepiece, turn the helical top up or down until that new eyepiece is focused as well. That's the correct setting for it. I don't touch the focuser at all unless I want some very fine focusing that involves less than, say, 1 or 2 mm focuser movement. Please note that corrector settings would be wrong for subsequent non parfocal eyepieces if you use the focuser instead of the helicap top of the coma corrector.

So you only need to know the correct setting for one eyepiece.

And if you don't even know the correct setting for one eyepiece there's a way to figure it out. Screw out the helical until the lower part of it it's 13.5 mm above the lowest possible setting as showed on this picture:

This way, the focus of the optical system will be exactly on the top end of the helical. I put a piece of translucent tape on the top end, and then, looking at a very bright object with the scope (I used Sirius, but it can be a bright planet or the Moon), I focus it with the scope's focuser on the "screen" created by the tape. The helical should be still at the 13.5 mm mark.

Now, if you knew the exact position of the field stop of your eyepieces, without touching the scope's focuser at all, you'd have to screw the helical in or out until the focus is exactly where the field stop is. So, for instance, if the field stop of an eyepiece is exactly where the body of a 2" EP meets the barrel you wouldn't need to touch anything. But that's not always the case. For instance, I need to screw my ES100 20mm in about 10 mm from that position (so the correct setting is 3-4 mm above the zero point of the scale) until it's in focus. That means the field stop of this eyepiece is 10 mm above the point where the EP's body meets the 2 inches barrel.

This may seem difficult or tedious but remember you only need to do it once. And believe me, once in the correct setting I can't see the slightest hint of coma in any of my eyepieces.

Hope it is clear enough. It's not easy to explain something like this when you're not using your native language.

Great that's very informative, thanks very much for such a detailed response. That does seem easier, I wonder why Televue don't adopt that method.

[bomberbaz]

10 hours ago, John said:

Doesn't the ES one need quite a lot of inwards focuser travel - around 38mm I read somewhere ?

If you have this then it's worth considering.

 

does the CC push the native focal point in or out from the start?

my nikon, which has the nearest focal point has around 20mm of additional inward travel when focused but my radian 5 actually requires you to pull it up it's barrel 5mm. Are any of the below likely to cause issue. i do have a 1.25" ext tube to deal with lack of outward but inward would be a problem.

steve

[Thonolan]

8 hours ago, Scooot said:

Great that's very informative, thanks very much for such a detailed response. That does seem easier, I wonder why Televue don't adopt that method.

 

I don't have a Paracorr but as far as I know you can use it the same way. Insert an eyepiece and use the tuneable top until it's the correct setting. Assuming it's in focus, you don't need to touch the scope's focuser anymore. Whenever you insert another eyepiece you just have to use the tuneable top until the new eyepiece is in focus. That's the correct setting for it. This way you won't need a red light to see the A, B, etc, marks, and won't need to remember the settings for each eyepiece either.

I see on your signature that you have TV eyepieces. Your 26mm Nagler needs setting "F" according to Tele Vue website. If that's the first eyepiece you're going to use that's all you need to know. Turn the tuneable top to F setting, focus, and when you're going to use a different eyepiece you just need to move the tuneable top until this new eyepiece is in focus as well. This is especially useful for non-TV eyepieces as there is no table with optimum settings anywhere for other brands.

[Uplooker]

I have owned a Type 1 TV Paracorr and currently use a Type 2 on my 12" Dob. The biggest difference I would highlight is that the Type 1 only has 1 off screw to lock the tuneable top. I found that this introduced an element of slop in the tuneable top if using a heavy EP. The Type 2 has 2 off locking screws on almost opposing sides. This locks the tuneable top more securely and eliminates the slop.

[Scooot]

1 hour ago, Thonolan said:

 

I don't have a Paracorr but as far as I know you can use it the same way. Insert an eyepiece and use the tuneable top until it's the correct setting. Assuming it's in focus, you don't need to touch the scope's focuser anymore. Whenever you insert another eyepiece you just have to use the tuneable top until the new eyepiece is in focus. That's the correct setting for it. This way you won't need a red light to see the A, B, etc, marks, and won't need to remember the settings for each eyepiece either.

I see on your signature that you have TV eyepieces. Your 26mm Nagler needs setting "F" according to Tele Vue website. If that's the first eyepiece you're going to use that's all you need to know. Turn the tuneable top to F setting, focus, and when you're going to use a different eyepiece you just need to move the tuneable top until this new eyepiece is in focus as well. This is especially useful for non-TV eyepieces as there is no table with optimum settings anywhere for other brands.

Ah, thanks again. Turning the tuneable top to focus and then locking it with the thumb screw is probably a bit stiffer and awkward than turning the helical ring on the ES but I'm going to try that. 

[Thonolan]

8 minutes ago, Scooot said:

Ah, thanks again. Turning the tuneable top to focus and then locking it with the thumb screw is probably a bit stiffer and awkward than turning the helical ring on the ES but I'm going to try that. 

No problem! The helical top of the ES coma corrector is very smooth in action indeed. Feels almost like an oversized 1:10 micro focuser wheel and doesn't need any kind of locking mechanism for any setting.

I learned these coma corrector tricks from Don Pensack (Cloudy Nights forum) who is one of the most experienced observers I know.

[alan potts]

2 hours ago, Uplooker said:

I have owned a Type 1 TV Paracorr and currently use a Type 2 on my 12" Dob. The biggest difference I would highlight is that the Type 1 only has 1 off screw to lock the tuneable top. I found that this introduced an element of slop in the tuneable top if using a heavy EP. The Type 2 has 2 off locking screws on almost opposing sides. This locks the tuneable top more securely and eliminates the slop.

Totally agree Ian, it is much better made altogether but for 400 quid it needs to be. I personally thought the edge sharpness was a bit better too having had the two together.

[alan potts]

2 hours ago, Thonolan said:

 

I don't have a Paracorr but as far as I know you can use it the same way. Insert an eyepiece and use the tuneable top until it's the correct setting. Assuming it's in focus, you don't need to touch the scope's focuser anymore. Whenever you insert another eyepiece you just have to use the tuneable top until the new eyepiece is in focus. That's the correct setting for it. This way you won't need a red light to see the A, B, etc, marks, and won't need to remember the settings for each eyepiece either.

I see on your signature that you have TV eyepieces. Your 26mm Nagler needs setting "F" according to Tele Vue website. If that's the first eyepiece you're going to use that's all you need to know. Turn the tuneable top to F setting, focus, and when you're going to use a different eyepiece you just need to move the tuneable top until this new eyepiece is in focus as well. This is especially useful for non-TV eyepieces as there is no table with optimum settings anywhere for other brands.

Learn something every day, it's logical when you think about it but why didn't I see it, Many Thanks!

[Firas]

On 17/02/2016 at 12:14, alan potts said:

Steve I wrote a review on both last year, it is in Members equipment somewhere, about 6 months or back.

Alan

Hi Alan! Where can i find your review?

Do you think a type 1 Paracorr would be as suitable for imaging with an f5 newtonian as with type 2? I found a second hand type 1 that is much less expansive than type 2. 

Thanks in advance 

/Firas  

[alan potts]

9 hours ago, Firas said:

Hi Alan! Where can i find your review?

Do you think a type 1 Paracorr would be as suitable for imaging with an f5 newtonian as with type 2? I found a second hand type 1 that is much less expansive than type 2. 

Thanks in advance 

/Firas  

It will be deep in the Members equipment section it was a few years ago now but still relevant today, I still have the Mk2 and it is a fine if somewhat expensive piece of kit, but then I find that true of all TeleVue, I have a fair amount of their eyepieces too. As for the imaging question, though I do AP it will be best for you ask on the Imaging section as a question, there are some excellent folk there that will help you. My guess would be as the difference between the Mk1 and Mk 2 concerned mainly only the edges then for AP with anything but a very large full frame sensor you should be fine.

Alan

[Don Pensack]

On 17/02/2016 at 01:28, bomberbaz said:

Just wondering from anyone who has owned both or just who knows the difference between the type I and type II.  

I note from the televue website that the type II has a 1.15 barlow effect to push out the focus but cannot find any info on the type I ref this.

Is the focus push out on the type one and two the same.

which gives the better control on coma. One would assume its the II.

I am not rushng out to buy one (heard this before) but one never knows.

Steve

In essence: the Paracorr 1 corrects a 40mm field width down to f/5 and is close to that at f/4.8.

The Paracorr 2 was developed for faster scopes and corrects a 40mm field completely down to f/3.5.

The Paracorr 1 had a range of 12.7mm, and some of today's eyepieces were outside the range of travel (notably 31mm Nagler and 21mm and 17mm Ethos).

The Paracorr 2 has a range of 17.8mm, and accommodates the modern eyepieces with very high focal planes.

The Paracorr 1 has 4 lenses, the Paracorr 2 has 5.

Both units have the 1.15x magnification primarily to avoid having to in-focus the eyepiece + Paracorr combination too far.  A good example is that the Paracorrs require about 14mm of in-travel compared

to the eyepieces alone, while the Explore Scientific HRCC requires 32mm of in-travel.

Where imaging is concerned, the tunable top is removed and the 2.4" adapter is added to either Paracorr.  Achieving focus will be the same with each.

At f/5, in imaging, you will not really see a difference between the two Paracorrs if set up properly.

Visually, you will see a difference, and most notably with the 3 eyepieces I mention and a few others from other companies.