Eye piece advise for 300p

[Geoff Barnes]

30 minutes ago, Barry-W-Fenner said:

How often do you get to use the 6.5?

Pretty much every outing Barry. It gives 230x so is very useful as a high power EP on a wide variety of targets from solar system to double stars and globulars and even galaxies and many nebulas.

Obviously good seeing is required but I feel 230x is not too much power in a 12 inch f5  Dob for many targets in average or better seeing conditions.

Food for thought. 😁

 

Edited July 31, 2020 by Geoff Barnes

[Don Pensack]

I use the 14mm Morpheus in a 12.5" newtonian, with Paracorr coma corrector, so f/5.75 effective f/ratio.

I use (and require) glasses at this focal length.  I use the eyepiece as a 1.25" at setting A in the Paracorr. That's the setting.

In my setup, the 14 Morpheus provides sharp, pinpoint, stars right up to the field stop and only deteriorates visibly exactly right at the field stop.

The performance really impresses, and the eye relief is nearly perfect for glasses.

That means, of course, that the eye relief is long.  I suspect that just about ALL visual observers who don't use glasses would require the eyeguard extension ring provided.

After all, Baader didn't provide them on the original shipments and got a real dressing down over the unfriendly eye relief for non-glasses wearers.

 

as for adding a Barlow, it's entirely possible the Barlow isn't very good.  If the scope is collimated, and cooled to the ambient temperature, you shouldn't have had much issue with 214x

as long as that magnification is under ~25x/inch of aperture.

 

[Barry-W-Fenner]

1 hour ago, Don Pensack said:

I use the 14mm Morpheus in a 12.5" newtonian, with Paracorr coma corrector, so f/5.75 effective f/ratio.

I use (and require) glasses at this focal length.  I use the eyepiece as a 1.25" at setting A in the Paracorr. That's the setting.

In my setup, the 14 Morpheus provides sharp, pinpoint, stars right up to the field stop and only deteriorates visibly exactly right at the field stop.

The performance really impresses, and the eye relief is nearly perfect for glasses.

That means, of course, that the eye relief is long.  I suspect that just about ALL visual observers who don't use glasses would require the eyeguard extension ring provided.

After all, Baader didn't provide them on the original shipments and got a real dressing down over the unfriendly eye relief for non-glasses wearers.

 

as for adding a Barlow, it's entirely possible the Barlow isn't very good.  If the scope is collimated, and cooled to the ambient temperature, you shouldn't have had much issue with 214x

as long as that magnification is under ~25x/inch of aperture.

 

Hi Don.

Very interesting read as always, thank you.

I have now attached the extension ring and put the eye piece to my eye. This feels much more comfortable than before. I didn't know that Baader added this to the kit because of the complaints of poor eye relief.

To the best of my knowledge the scope Is collimated well.  It was also well cooled last night as it had been out for about two hours before use.  The eye piece gave some great views, maybe the slight deterioration was down to my eye not being comfortable at the eye piece which caused some strain??

Unfortunately I think you and some. Other members are probably correct about my barlow. Its not the most expensive option out there and may not be suited to the Morpheus range. Do you use one with your morphs? If so what do you recommend /use.

 

Thank you

Baz

 

[Louis D]

If you have a coma corrector that also flattens the field, it is possible to see that the 14mm Morpheus has a very slightly curved field in the last 15% of the field.  I also confirmed this in a field flattened ED refractor.  By comparison, the 17mm ES-92 is dead flat to the edge in the same scopes despite being significantly wider.  You can confirm this for yourself by moving a bright star from best focus in the center to the edge and seeing if it needs refocused there.  However, if you don't have a flat field scope, you won't be able to be certain where the field curvature originates from.

The 14mm Morpheus also has slight astigmatism at the edge (unlike the 17mm ES-92).  Again, put a bright star at the edge and rack it through focus from inside to outside of best focus.  If the star changes from a radial to a tangential line (flattened oval) on either side of focus, that's what astigmatism looks like.

It's likely, though, that coma could be what you're seeing a the edge, especially if you're not using a coma corrector in a Newt.  It will make a bright star look like a pointed tear drop with the point aimed at the center.

[JOC]

FWIW I wear specs and never use any of the provided eyecups on any of my EP's I just hover above them at appropriate height to see things nicely.  The only thing I've ever had which I need to use eye cups on, strangely is my new (2nd hand) bins that I got from SGL they are Nikon prostaff P511 10x50 and just will not become useable unless I've wound out the eye cups.

[Alan White]

I suggest that you get your eyes tested Baz, you may have Astigmatism that you are becoming aware of.

And you may be seeing the coma present in your scope, it’s a Newtonian, it has coma.

 

[Guest]

On 18/07/2020 at 09:36, Barry-W-Fenner said:

Thank you Ricochet, I will check all of the above when I set up tonight.

I did some viewing from 10pm to 12am last night, I let the scope cool for a good two hours before use. Stars looked much better than previously. I had a look at a number of targets and they were all very clear in the 8 & 12mm bst,s

I got back out at 4am after a few hours kip to see Mars. It looked amazing with my 5mm & 8mm bst,s a very clear phase with different shade of colour to the planet. The southern ice caps stood out extremely well. They are a very appealing characteristic of Mars to view.

regards

Baz

Did you get you try the 3.2mm BST on Mars yet?

[Guest]

21 hours ago, John said:

You can use the extension piece to move the eye cup a bit further away from the eye lens which might help with eye positioning Barry. Try it and see.

I didn't get on with those "winged" eye cups but some people like them.

The Morpheus is a 1.25" eyepiece. Some folks prefer using these larger eyepieces in a 2 inch fitting because they feel more secure which is why some have a hybrid barrel design.

I would guess that the BST Barlow is the weak link in the optical train compared with the Morpheus optics.

 

 

I have somewhat of a phobia about things being near my eyes, so those wing eyecups would be a no-no for me!  I've gone off the fold up ones, much preferring the twist/screw up variety that the BST's offer.

Edited August 1, 2020 by Guest

[Barry-W-Fenner]

18 hours ago, Louis D said:

If you have a coma corrector that also flattens the field, it is possible to see that the 14mm Morpheus has a very slightly curved field in the last 15% of the field.  I also confirmed this in a field flattened ED refractor.  By comparison, the 17mm ES-92 is dead flat to the edge in the same scopes despite being significantly wider.  You can confirm this for yourself by moving a bright star from best focus in the center to the edge and seeing if it needs refocused there.  However, if you don't have a flat field scope, you won't be able to be certain where the field curvature originates from.

The 14mm Morpheus also has slight astigmatism at the edge (unlike the 17mm ES-92).  Again, put a bright star at the edge and rack it through focus from inside to outside of best focus.  If the star changes from a radial to a tangential line (flattened oval) on either side of focus, that's what astigmatism looks like.

It's likely, though, that coma could be what you're seeing a the edge, especially if you're not using a coma corrector in a Newt.  It will make a bright star look like a pointed tear drop with the point aimed at the center.

Hi Louis

That's spot on what  I am getting. The stars are fine points that turn more tear drop and a have a point at the bottom as they drift to the field edge.  Regarding coma corrector, what would be the best option for a 12" dob?

[Barry-W-Fenner]

12 hours ago, merlin100 said:

I have somewhat of a phobia about things being near my eyes, so those wing eyecups would be a no-no for me!  I've gone off the fold up ones, much preferring the twist/screw up variety that the BST's offer.

Hi Merlin.

Unfortunately I haven't tried the 3.2 on mars yet. Conditions haven't been great.. I hope to soon though!

Regarding the eye Cup on the Morph, it was quite difficult to get a comfortable eye position the 1st time I used it. However with the extension added it is extremely comfortable. Just holding it to my eye it feels so much better. I am really looking forward to trying it out!

Baz

 

Edited August 1, 2020 by Barry-W-Fenner

[Guest]

17 minutes ago, Barry-W-Fenner said:

Hi Merlin.

Unfortunately I haven't tried the 3.2 on mars yet. Conditions haven't been great.. I hope to soon though!

Baz

 

I look forward to reading your thoughts on the 3.2mm on Mars, whether that's with 200P or 300P.

[Barry-W-Fenner]

Just now, merlin100 said:

I look forward to reading your thoughts on the 3.2mm on Mars, whether that's with 200P or 300P.

I am really hoping that both Venus and Mars  will look great with the 3.2, just need favorable seeing conditions now. I'm not asking much am I 😂

[Guest]

Try being up here, we've had nearly constant cloud cover overnight, for the last 6 weeks! ☹️

[Don Pensack]

1 hour ago, Barry-W-Fenner said:

Hi Louis

That's spot on what  I am getting. The stars are fine points that turn more tear drop and a have a point at the bottom as they drift to the field edge.  Regarding coma corrector, what would be the best option for a 12" dob?

I've used a few, and can point out the convenience of use:

TeleVue Paracorr: easiest to use and dial in the correction for any eyepiece

Explore Scientific HRCC: wide range of adjustment, can be used for fine focusing, hard to use if eyepieces focus a distance apart, easy to use if eyepieces are nearly parfocal.

GSO coma corrector: hard to dial in for individual eyepieces, but fairly easy to use if eyepieces are parfocal.  More difficult to optimize than the 2 above.

Baader MPCC: unless you have a pile of spacers on the eyepieces, this one is very difficult to optimize for individual eyepieces.  Not great correction either.

https://www.astrofotoblog.eu/?p=856

 

[Louis D]

5 hours ago, Barry-W-Fenner said:

Hi Louis

That's spot on what  I am getting. The stars are fine points that turn more tear drop and a have a point at the bottom as they drift to the field edge.  Regarding coma corrector, what would be the best option for a 12" dob?

The best option without doubt would be the Paracorr T2 at 495 GBP.  However, if your pockets aren't that deep, the GSO/Revelation CC is quite good for 65 GPB.  I use it in my Dob to good effect.  It does need a 25mm spacer tube between the optical section and the eyepiece holder.  As long as all your eyepieces focus within 5mm of their shoulder, coma will be corrected to within about 95% or better of optimal.  I only had to parfocalize one eyepiece, my 12mm Nagler T4 because it focuses 20mm from its shoulder, so coma was noticeable with it without parfocalization.

I've found it to be plenty good enough that I've never felt the need to upgrade to a Paracorr.  It does need removed for highest power work because it contributes a bit of spherical aberration visible only under those conditions.  It's my understanding the Paracorr T2 does not, so there is that.

The GSO/Revelation requires 11mm of in-focus, which is similar to the Paracorr.  The ES HRCC requires 31mm, IIRC, which is a lot more and beyond what I have available.

[Don Pensack]

This thread points out how to set up the GSO coma corrector:

https://www.cloudynights.com/topic/462985-setting-up-the-gso-coma-corrector/