North Group APOs - Page 8

wasyoungonce (Brendan) · #**141** 07-08-2010, 12:07 AM

Quote:

Originally Posted by DavidU

that's a very good report indeed. It's German.

It does look ok...better than the earlier Meade 127ED report he did (un-known date) half way down this page.

He appears to work for Tuebingen Uni. Looks as if he has tested lots of scopes from RCOS to the ED80.

Interesting..but "I no nothing..." of German!

Would love to find out why he shimmed the optics of the127ED? Lord his pages are hard to navigate!

wasyoungonce (Brendan) · #**142** 07-08-2010, 10:11 AM

Ok for anyone who's interested in the 127ED.

This gent Wolfgang Grzybowski's tested a 127ED scope under the generic name "OMEGON" (at the bottom of the page). He had big troubles with it with: coma; astigmatism; and what appeared as a flare (blue/violet) (I'm reading into that but his pics show this was happening).

To give you an idea of how bad it was..the Strehl was .17!

and the rest of the figures were poor as well.

He inserted new spacers, re-shimmed & adjusted the lenses and ended up with Strehl of .93. Much better.

This looks pretty much as what I was getting in my scope. I was also getting funny shaped stars across the field with coma and flaring.

It appears he liked it after he did the adjustments.

I hope mine (lens cell) comes back as good as this?

edit:

It appears..l ens spacers are available (or suggested) in Europe as a retro fit for these lenses. He also appears to have some commercial interest in this OMEGOM brand as they listed his Optics adjustments "guaranteed performance" from the astroshop.de selling these scopes. Thus he must test and adjust each scope.

JohnH · #**143** 07-08-2010, 11:23 AM

Arghh! Brendan,

I just caught up with this thread - and I feel awful - the advanced focuser made things worse - I am so sorry - quite happy to swap it all back and give you a refund mate.

On another note great that you have gone into this so deeply and good that gilman is responding too.

Re-spacing a triplet lens is not for the faint hearted that is for sure...but I am intested to see how your scope goes after a factory calibration (or replacement), as I read it getting the three lenses just right is a black art - rotating each element independantly and re-testing each time to get a best result - eeek.

John.

wasyoungonce (Brendan) · #**144** 07-08-2010, 11:38 AM

Hi John.

No it's not the focuser. Your offer is thoroughly decent...but the original focuser had off axis issues as well.

I managed to centre/tilt adjust the advanced focuser somewhat to get nice flat field analysis and centred optics..happy with that. Yet the scope still showed coma (actually astigmatism) and chromatic flare.

This German site shows that indeed these issues are due to the lens spacing and adjustments. He appears quite thorough and not superfluous on his words but it does appear he tests scopes for astroshop.de (and vegaoptics.de)... so be careful of commercial relationships and their tests! That said..I'd be happy with an expert backing the scopes I am buying and they appear to be guaranteeing results.

It's indeed a learning curve but I wouldn't have it any other way! The only way to learn is to make mistakes! It makes interesting reading for those who have the scopes.

I'm sending Gilman some info from this site. I don't know Gilman's position in Hioptic/Northgroup..aka is he a technician? So, I don't know if this will be well received nor passed on.

wasyoungonce (Brendan) · #**145** 26-08-2010, 12:19 PM

Update: New lens cell being sent out to me.

Gilman said that my lens tested ok on the optical bench but stated something along the lines that... "yes we know you have trouble with it". It's difficult to tell in translation..and they might not want to say to me "you're an idiot" or "yes there is an issue"?

So, I cannot state what they are thinking wrt to my cell but in short they are sending out a new cell.

Gilman has been very helpful. I cannot fault their assistance or customer care.

I have trolled CN and it appears "only one" other user had a similar issue to me. I got to say, out of hundreds ~ thousands of these being sold around the world (under different names)...that's pretty damn good.

I'll post back when its up and running ...and the damn clouds clear.

Sylvain (Jon) · #**146** 02-09-2010, 02:15 PM

Hey everyone,

I was just wondering if any of you know whether Gilman and North Group are able to supply the 102 apo refractor?
Their alibaba page mentions only the 80mm and 127mm, but I would rather get the 102 as it's less bulky than the 127 but offers more aperture than the 80.

Any feedback would be appreciated!
Cheers

wasyoungonce (Brendan) · #**147** 15-09-2010, 01:05 PM

Received new lens cell from Northgroup yesterday. A big thanks to Gilman on this. They bent over backwards in helping me.

Managed just a little peek at the sky last night before clouds rolled in. The air was quite turbulent so tests are taken as a grain of salt. However it looks very encouraging. Acid test..Venus. Small amount of fringing...60% less than previous. This (fringe) is expected given Venus is so bright at the moment.

Moon shots came up quite good and some focusing tests good as well. Here is a small de-focused test on Beta Centauri..which is a very blue star. The main thing is that fringing is pretty much concentric with the star.

I tried to snap the ptolemy cluster but clouds beat me and I didn't get focus accurately..so maybe next time. There is still some fringing but as I said it's concentric with the stars which is encouraging.

DavidU (Dave) · #**148** 15-09-2010, 04:52 PM

Looking good !

Octane (Humayun) · #**149** 15-09-2010, 06:02 PM

Fabulous news, Brendan.

Can't fault Gilman for service.

He emailed me and was asking what to do with your case. I asked if a replacement lens cell had been sent out and at the time he said he would send one shortly.

H

wasyoungonce (Brendan) · #**150** 15-09-2010, 07:30 PM

Gilman has been just great. It certainly shows their thirst for consumer confidence in their products. As I said there is only one other case of someone else who wasn't that happy with their lens performance (their scope was replaced..an ES product). Of all their scopes sold around the world...that pretty good.

The main difference I saw with this lens is that that any chromatic aberration was concentric with the stars. I wanted to take some snaps of the Ptolemy cluster as it has a high grouping of quite blue stars.

Venus is an acid test for any refractor and I'd expect some fringe on this. I noticed the moon pics showed less fringe.

Hopefully the clouds will clear and I can post more results soon.

DavidU (Dave) · #**151** 15-09-2010, 07:40 PM

It is great of Gilman. It's unusual as I had the money for a 127 but gave up trying to get hold of him.

JethroB76 (Jeff) · #**152** 15-09-2010, 08:36 PM

Quote:

Originally Posted by Octane

Fabulous news, Brendan.

Can't fault Gilman for service.

He emailed me and was asking what to do with your case. I asked if a replacement lens cell had been sent out and at the time he said he would send one shortly.

H

He asked for your advice in dealing with another customer?

Great result btw

Octane (Humayun) · #**153** 15-09-2010, 09:29 PM

Jeff,

Yeah, it's happened a couple of times now.

I've forwarded a lot of people his way, and, so he somehow respects my opinion -- despite me knowing absolutely zilch about optics. It's gold. He's offered to send me out accessories and what not for my help. So sweet, lol.

H

wavelandscott (Scott) · #**154** 15-09-2010, 10:12 PM

Quote:

Originally Posted by wasyoungonce

Gilman has been just great. It certainly shows their thirst for consumer confidence in their products. As I said there is only one other case of someone else who wasn't that happy with their lens performance (their scope was replaced..an ES product). Of all their scopes sold around the world...that pretty good.

Not to detract from the good service and outcome in this instance but do be careful with your generalization and assumptions...not that I know otherwise either but the insertion of "to my knowledge" might be a good addition to your statement.

I'm glad it is all working out and that you are happy (as it seems are others).

JethroB76 (Jeff) · #**155** 15-09-2010, 10:14 PM

Quote:

Originally Posted by Octane

Jeff,

Yeah, it's happened a couple of times now.

I've forwarded a lot of people his way, and, so he somehow respects my opinion -- despite me knowing absolutely zilch about optics. It's gold. He's offered to send me out accessories and what not for my help. So sweet, lol.

H

That's awesome- you scope guru!!

wasyoungonce (Brendan) · #**156** 15-09-2010, 10:16 PM

Hi H...Thanks.....I kinda guessed that they were at a bit of a loss what to do about this all. Thanks for the input.....Gilman thinks highly of you...the class favourite

.

The lens cell is probably most expensive part so replacement is not done frivolously.

I guess they are also not really set up for repair/replacement...so it was new to them as well.

Anyway..when the clouds clear...more play!

wasyoungonce (Brendan) · #**157** 15-09-2010, 10:19 PM

Quote:

Originally Posted by wavelandscott

Not to detract from the good service and outcome in this instance but do be careful with your generalization and assumptions...not that I know otherwise either but the insertion of "to my knowledge" might be a good addition to your statement.

I'm glad it is all working out and that you are happy (as are many others).

Point taken...although it's well known that the unhappy make the most noise...internet noise that is

netwolf · #**158** 15-09-2010, 11:56 PM

I have found Gilman will eventuall respond, sometimes it just takes some time. Unfortunately havent got around to saving enough penies to buy anything yet.