To Paracorr or Not to Paracorr...

[estwing]

simonfromsussex wins at 3.4...I waited for so long for a paracorr 2 to come up second-hand,just didn't happen so I bought mine on offer at the hertsy festival along with the 21 ethos...cheap weekend!!.very happy with mine indeed as I am with my whole set-up....content calv!

[Paul73]

So we now have the question. Paracorr 1 or 2???

Sorry to complicate things. But with the eyewatering price difference between used Mk1 and New Mk2. Under what circumstances Is it worth the extra?

Paul

[estwing]

paracorr mk1 was designed before the ethos.... paracorr 2 was designed to accommodate said range..

[Paul73]

So the Mk 1 will do the same job as the Mk 2 if you stear clear of the 100°+ exotic eyepieces?

Paul

[John]

So the Mk 1 will do the same job as the Mk 2 if you stear clear of the 100°+ exotic eyepieces?

Paul

Trouble is, once you have looked through an Ethos with a really large aperture dob, you don't want to steer clear of them !

[Paul73]

Trouble is, once you have looked through an Ethos with a really large aperture dob, you don't want to steer clear of them !

I've enjoyed 16" + Ethos. And, yes, I do want them very badly indeed. But I choose not to indulge....

Poverty can be an excellent substitute for will power.

Every time I get the urge. I buy a new eyepiece to restore my will power.

Paul

[John]

.....Poverty can be an excellent substitute for will power.

Thats very true

[alan potts]

paracorr mk1 was designed before the ethos.... paracorr 2 was designed to accommodate said range..

Many thanks Calvin, you have done it now   I have to get one or get rid of all my Ethos's and Delos as it will not account for those , I will have to sell my other kidney .

Alan

[estwing]

There are more eyepieces than organs I'm afraid Alan!

[alan potts]

Every time I get the urge. I buy a new eyepiece to restore my will power.

Paul

Paul,

I have plenty of will power, it's won't power that escapes me.  I am sure you will be happy with a Mk 1 Paracorr, I am and I have tried it in the my Dob with a few ethos eyepieces and it seemed fine. The price difference is significant as PC MK 2 is very rare S/H, a closer inspection is required of the edges before I blow another 400 quid.

I think also something that works in the favour of a little edge softness in a Dob is the stars are not still like in my driven scopes, that way I don't really study them in the same way, more noticeable at higher power of course.

[YKSE]

I've enjoyed 16" + Ethos. And, yes, I do want them very badly indeed. But I choose not to indulge....

Poverty can be an excellent substitute for will power.

Every time I get the urge. I buy a new eyepiece to restore my will power.

Paul

I'd like to think that responsibility and knowledge can be of some help to will power too

[Stu]

I'd like to think that responsibility and knowledge can be of some help to will power too

Let me think about that for a moment..........

.....err, sorry, doesn't seem to work for me!! [emoji6]

[stepping beyond]

I've got a f4.7 dob and a f3.9 newtonian and the Paracorr type 2 is a compliment to both reflectors. I view with Z100'S and Nagler 3-6mm zoom and in the wider eps you see the tale. The Paracorr is more than just a coma corrector and it's use is versatile 4x , much better than the original. 4 years of awesomeness and made my  scopes and quality eps much better than if I didn't own one. I've had plenty of opprotunities to sell it off but, I stick with the quality and versatility in this ocular. It doesn't fit in everyones ep kit but, it's a keeper in mine and had light years of use.

[niallk]

So after saving for several months, I took the plunge! Usual excellent service from TS. There might even be a chance to test in a gap in the clouds this evening...

Have had a look at balance (no counter balance at all added yet, but can do), and it seems OK with a Pan24+PM2.5x ... almost the same weight as a 10mm Ethos - a possible target to save up for next

Thanks for all the feedback on this thread.

[estwing]

Looks like you took my advice!...congrats it will clean up the views tremendously...re the 10mm ethos...go for the 8mm it's the second best ethos.I wasn't convinced until swampthing to me about how it performs in big dobs...simply stunning

[John]

That looks superb - the whole setup just oozes quality

[Don Pensack]

Once you see what it does to star images, you won't want to live without it.

Personally, I think it is essential to f/6 and even desirable to f/8, though that does depend on the apparent field of your eyepieces.

The wider the apparent field, the more essential is coma correction, since more of it is revealed.

Take any focal length of eyepiece, and the wider the apparent field, the farther out into coma land the field extends.

On an f/4.5 dob, only the central 0.46mm of field is coma free (coma is smaller than the Airy Disc).

Even a 2.5mm Nagler has a field stop 3.4mm wide, over 7x as wide as the coma free zone.

[Piero]

Just read a page which explains coma very clearly on CN, with comments from Don and other members: 

http://www.cloudynights.com/topic/484401-formula-for-coma-free-zone/

Really interesting subject to me. Thanks very much!

Quite funny that 1. after buying top notch optics to limit aberrations as much as possible, and 2. after driving to dark places to get the best skies, one faces coma in fast telescopes! 

I have to say that I agree with estwing.. if a gentleman / lady buys excellent and expensive equipment (e.g. fast telescope + ultra wide eyepieces), saving on a coma corrector makes little sense to me, as it is quality what this person is looking for. Of course it is up to each of us to establish the f-ratio threshold defining whether a parrcorr is required. 

Trying before buying seems the best way, although it seems that trying this tool leads to a straight purchase!

Have clear sky Niallk and enjoy your next observations! 

Looking forward to reading your future reports!

Piero

[Uplooker]

So the Mk 1 will do the same job as the Mk 2 if you stear clear of the 100°+ exotic eyepieces?

Paul

Just to add my tuppence to this debate, I started off with a Paracorr Mk1 on my SW 300PDS, which is f4.9. I was very happy with the views and improvement / elimination of coma. I was however disappointed with the slop that existed because of the single screw on the tuneable top, when a heavy EP was used i.e. Nagler 26mm. Others have mentioned the improvements in the Mk2 as being more towards being able to use wider field EPs. That may well be true, but I found the biggest improvement was from the addition of a second screw, on the opposing side of the tuneable top, from the other securing screw. YMMV

Well done on the new addition nialk, you will enjoy it and the improved views. I have found that as time rolls on your memory becomes very short / selective when you spent large amounts of money

[Paul73]

Good point Ian. You would have thought that TV would have spotted / fixed that straight away. Particularly as they were, at the time, manufacturing the world's heaviest production eyepiece!!

Paul

[Moonshane]

I have the later type one which has two additional 'button bolts' on the opposite side to the tensioner thumb.

Really makes a difference to the issue Ian mentions - although I think that issue affects mostly the lighter eyepieces so less than you'd think?

Whilst I use the paracorr almost all the time, if I do find that I'd like just a  little more true field, I just take it out and use without the correction - not the end of the world. I really like the ease of use - the sips system must be even better in this respect.

[estwing]

Just read a page which explains coma very clearly on CN, with comments from Don and other members:

http://www.cloudynights.com/topic/484401-formula-for-coma-free-zone/

Really interesting subject to me. Thanks very much!

Quite funny that 1. after buying top notch optics to limit aberrations as much as possible, and 2. after driving to dark places to get the best skies, one faces coma in fast telescopes!

I have to say that I agree with estwing.. if a gentleman / lady buys excellent and expensive equipment (e.g. fast telescope + ultra wide eyepieces), saving on a coma corrector makes little sense to me, as it is quality what this person is looking for. Of course it is up to each of us to establish the f-ratio threshold defining whether a parrcorr is required.

Trying before buying seems the best way, although it seems that trying this tool leads to a straight purchase!

Have clear sky Niallk and enjoy your next observations!

Looking forward to reading your future reports!

Piero

...I have a fan!

[Moonshane]

yeah, Calv it really helps with cooling.   

[niallk]

Thanks for all the interesting comments, explanations and advice guys - always appreciated!

Opening the box I was impressed and taken aback at the physical size … note I've only got 1.25” eps (so far!). You know, one of the first things I checked was for any play with the tunable top set - just as you guys mentioned re the original model. It seems very solid to me.

Amazingly, there was a gap in the clouds the night after it arrived, and I put the scope out to cool for over 2hrs, with the fan on. When kids were finally asleep & chores done, I went out - the scope had a good crust of frost. I even suspected that the primary looked a bit hazy when collimating. I started looking at the Pleiades with the Pan24 and 13T6 with and without the Paracorr, and positioned stars at the field stop. Stars looked tighter with a flatter field - looked to be cleaning up the views!

However, unfortunately things didn't really go to plan: neighbour's floodlight kept being turned on, ruining me having a look a a few galaxies as I'd hoped. Then after my dark adaption returned somewhat, I swung over to M81/82. The views just weren't right, so I had a peek, and sheesh - the secondary was badly dewed. I think I need to adjust the factory settings on my Astrosystems dew heater in the secondary holder - but I think it was a challenging night with dropping temps and humid air. It was getting late with work in the morning so I packed up.

Will try again next opportunity - must get up early for Jupiter & Venus and to try for Catalina, and hopefully get some better seeing - been plagued by not great conditions for most of this year tbh. I seem to generally find Polaris in the bottom 3 ratings in the Pickering scale per Damian Peach’s animations:

http://www.damianpeach.com/pickering.htm

The weather and jetstream Forecast doesn't look great for the next few days… but hopefully get some nights over the Xmas period, even though the moon will be full.

Re an 8mm Ethos - yeah with the Paracorr, it would give approx 245x similar to my 7mm Nagler. The 7T6 has sees lots more use in my 15” than my 250px - on planets, moon and planetary nebs. It's a great ep. I also tend to binoview at ~240x with my pair of 15mm plossls for planets.

The reason I've been considering a 10mm is to back off on mag a bit given seeing has been relatively poor for so long - towards 200x with wider afov. A 10mm/8mm Ethos/Delos or 9mm Nagler are all candidates… lots of time to consider options better while waiting for the astro savings pot to recover

[estwing]

glad you like the new toy....the dew didn't drop till 12ish last night in Snowdonia,lucky really...clear skies mate.