StellaLyra Photo/Visual Coma Corrector (f4)

[kev100]

Hi,

I (finally) got one of these as a birthday present, for use with my 250PX.  It came in a nice, black cloth covered box, with foam inserts, and at 359 grammes feels solid and value for money in the hand. I'd read a Stargazers Lounge post about them, and one person mentioned that the eyepiece retaining screws are flimsy pot metal, so I compared the weights with the screws from my RevelationAstro 2in eyepiece adapter and, sure enough, there was a noticeable weight difference (2 grammes versus 3 grames), so I swapped them over. This is interesting as both items are made by the same company (GSO).

Popping the caps off to take a look at the lens inside left me horrified at what I thought was a scratch. This turned out to be a bit of plastic swarf from the end caps (my dust blower took care of it). Curiously, though, there was quite a lot ...

In use, it's a direct replacement for the aforementioned eyepiece adapter. Eyepieces come to focus easily, and don't need to extend any further from the focuser (I have heard some people say they needed to use a spacer ring to achieve focus, but in my 10-inch dob - f4.7 - there was no need). Maybe that's a photo thing ...

How well does it work? Well, on the two sessions I've had with it so far it worked really well. Actually very well. The field of view with my 20mm 100-degree Myriad was impressively flat, and stars were pinpoint sharp almost to the very edge. Likewise with my 68-degree, 16mm MaxVision. Even the dense star-filled Milky Way between Sadr and Albireo didn't suffer from coma, and the Double and Owl clusters were stunning. Without the CC the views of this area always appeared as if seen on the surface of a bubble, but not now ... flat as a pancake.

Recommended.

[Mr Spock]

I'm using one in my 8" f4. Without it coma is horrific, even with a 13mm eyepiece. With it it corrects to the point where my 30mm UFF is sharp to the edge. 

[kev100]

Wish I'd got it ages ago 😔

[Captain Scarlet]

@Nicola Fletcher might be interested in this. It looks like a cost-effective way of discovering whether you get benefit from a CC without blowing £500 for a Paracorr2. Its specs look remarkably similar to the PC2 actually.

Magnus

[Nicola Fletcher]

46 minutes ago, Captain Scarlet said:

@Nicola Fletcher might be interested in this. It looks like a cost-effective way of discovering whether you get benefit from a CC without blowing £500 for a Paracorr2. Its specs look remarkably similar to the PC2 actually.

Magnus

Thanks Magnus, really good idea. I don’t want to splash out on a Paracorr unless I really think I’ll need it. 

[Louis D]

On 13/10/2023 at 14:10, kev100 said:

Eyepieces come to focus easily, and don't need to extend any further from the focuser (I have heard some people say they needed to use a spacer ring to achieve focus, but in my 10-inch dob - f4.7 - there was no need). Maybe that's a photo thing ..

I needed to add a 25mm spacer ring between the optics section and the eyepiece holder to achieve the best coma correction for eyepieces focusing at the shoulder, which is most of my collection.  This then required 11.3mm more in-focus with the CC in place than without.  Without the extra spacing, stars were still a bit comatic in the last 15% of ultrawide field eyepieces.

Edited November 13, 2023 by Louis D

[kev100]

On 13/11/2023 at 00:26, Louis D said:

I needed to add a 25mm spacer ring between the optics section and the eyepiece holder to achieve the best coma correction for eyepieces focusing at the shoulder, which is most of my collection.  This then required 11.3mm more in-focus with the CC in place than without.  Without the extra spacing, stars were still a bit comatic in the last 15% of ultrawide field eyepieces.

Which brand/type of eyepieces are you using?

[Mr Spock]

On 13/11/2023 at 00:26, Louis D said:

I needed to add a 25mm spacer ring between the optics section and the eyepiece holder to achieve the best coma correction for eyepieces focusing at the shoulder, which is most of my collection.  This then required 11.3mm more in-focus with the CC in place than without.  Without the extra spacing, stars were still a bit comatic in the last 15% of ultrawide field eyepieces.

I'm not seeing that with a 30mm UFF. What scope are you using?

[Louis D]

Pentax XLs, XWs, ES-92s, 30mm UFF, ES-82, etc.

[kev100]

On 17/11/2023 at 14:34, Louis D said:

Pentax XLs, XWs, ES-92s, 30mm UFF, ES-82, etc.

Nice set of EPs you've got there.  Can't think why you need the spacer, though. I don't with mine, even the 20mm Myriad. 

[Mr Spock]

On 17/11/2023 at 14:34, Louis D said:

Pentax XLs, XWs, ES-92s, 30mm UFF, ES-82, etc.

 

On 17/11/2023 at 14:07, Mr Spock said:

What scope are you using?