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GBT 100/90 arrived

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#1 contrailmaker

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Posted 20 March 2010 - 06:35 PM

Well, I know everybody has been waiting to hear about these.

Just received mine earlier today. Mounted them on the Orion versa-go and went on to look them up thoroughly. The main thing everybody wants to know first.

Looking from the eypiece side, three sides of the prism edges are clearly seen. Looking through my 25mm EPs they are also visible. The exit pupil shows only one cut-out at the very top that seems to cover perhaps less than 10% of the disk. Not bad.

I measured the objective lens diameter using the flashlight method and more directly using the measuring tape near the objectives, being carefull not to touch the lenses. Both came to 95mm. Rough measurement here, but definitely smaller than 100mm. So far, so good.

The left eyepiece holder was very hard to open to where the EPs would fit. I did not want to force anything so I just turned it to the stop and the eyepieces fit although very tightly. The problems came when I tried to focus the left side. All eyepieces would come more or less close to focus but the image was very distorted. I have never seen anything like this before on a scope. Same result with all EPs tried including the shipped EPs. Don't know if this is the result of the prisms shaken out of position during transport. Nothing seemed loose and no rattling sounds.

The right side worked flawlessly. Easily coming to sharp focus and no issues with the EP holder. The interpupilary distance adjustment seemed smooth and precise but the images were so disparate that I was only able to do a very rough collimation check. At 24x I could merge one sharp image with the other very blury image. No sense to continue from there.

Looking with a flashlight into the objectives, the inside of the tubes were nice and clean, but the objectives were not. Both had small but clearly visible coating blemishes and both had fingerprints on them.

What a drag. These are going back for replacement. I will give GO the chance to make it right. Stay tuned.

cm

#2 elwaine

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Posted 20 March 2010 - 07:32 PM

CM, did they come with a certificate saying they had passed the 14 point inspection?

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#3 pcad

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Posted 20 March 2010 - 08:09 PM

I had a similar experience with the first Apogee RA88SA I received. The second one wasn't perfect either, but was usable. Sorry to hear that you're having a similar experience.

#4 GlennLeDrew

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Posted 20 March 2010 - 08:33 PM

I'd like to be a fly on the wall in the factory. Just how many corners are the assemblers required to cut in order to move product out the door in the minimal time?

I'm becoming increasingly convinced that while cheap scopes can be had with a reasonable degree of confidence, the chances of a satisfactory outcome scale as the inverse of the square of the number of objectives. (For the mathematically-challenged, two objectives result in a confidence factor 1/4 that for a cyclopean instrument.)

#5 Wes James

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Posted 20 March 2010 - 10:07 PM

Very disappointing report. I'd be very unhappy. Really makes me distrust their 14 point inspection. And I'm very sorry to have to say that. It's just not getting any better, it seems. I will say that I had my 20x110's out tonight, and find them very enjoyable... and everyone who views through them are impressed. It's too bad the same can't be said for their 100mm 45/90* bino's.

#6 beachchairbill

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Posted 20 March 2010 - 10:32 PM

Anyone have a list of the 14 points.

I have number 15 and it's the flashlight test and that's the one that shakes up the purchaser.

Kenny - have you started your inner list yet - eh.

Beachchairbill

#7 Photoner

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Posted 20 March 2010 - 10:33 PM

The 14 points are not listed. My big GO's arrived with a total factory defect [mounting threads so fouled could not mount the unit to a tripod] and had to bounce back for repair (direct replacement was not offered) and then there was the recent post (above) on internal casting defect on another unit so we're up to 16 points needed at least.

Quote the raven

#8 KennyJ

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Posted 21 March 2010 - 03:50 AM

Sandycoastreclinerwill ,

Rest assured I am keeping tabs and remaining inert .

I am a wiser man this morning after breakfasting on these two threads -- and also a wider man -- following my belated birthday meal out last night !

Kenny

#9 Mr. Bill

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Posted 21 March 2010 - 02:21 PM

Interesting the difference in the two reports of the effective aperture measurement using flashlight method. on the GTB100 90s...

This report of 95mm and a previous report of 80mm, certainly well beyond differences in measurement error.

The raytrace analysis that Glen and I discussed on the other thread "Anyone purchase the GTB 100/45 past six months" (and EdZ mentioned prior to that on the same thread) shows severe vignetting that would make the actual number closer to 80mm than 95mm.....

:question:

#10 Mr. Bill

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Posted 21 March 2010 - 02:25 PM

I'd like to be a fly on the wall in the factory. Just how many corners are the assemblers required to cut in order to move product out the door in the minimal time?

I'm becoming increasingly convinced that while cheap scopes can be had with a reasonable degree of confidence, the chances of a satisfactory outcome scale as the inverse of the square of the number of objectives. (For the mathematically-challenged, two objectives result in a confidence factor 1/4 that for a cyclopean instrument.)


Don't forget that binoculars also have many reflective surfaces in the prism group and interbarrel collimation issues....I'd say that increases the chances of problems many fold beyond your estimate.

:cool:

#11 GlenM

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Posted 21 March 2010 - 03:30 PM

I am really disappointed for you. I hope everything can be sorted out to your satisfaction.

#12 Mr. Bill

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Posted 21 March 2010 - 03:39 PM

It would seem to me that all these returns on Garrett's dime for defects would really eat into the profit margin...would'nt it be cheaper and easier to REALLY do the 14 point inspection? The gross defects discussed on this thread and the recent others would easily be detected with the most casual visual inspection.

Makes one wonder whether the collimation check was done.

:tonofbricks:

#13 GlenM

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Posted 21 March 2010 - 03:43 PM

I must say that these problems certainly need looking into for sure.

I feel so disappointed for people who have problems.

#14 beachchairbill

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Posted 21 March 2010 - 07:51 PM

What are the 14 points of inspection? I'm sure we can come up with the points that were not checked.

Beachchairbill

#15 mtb54703

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Posted 21 March 2010 - 09:47 PM

I too currently have a pair of the Garrett Optical 90 Binocular Telescope, at least until tomorrow. I would like to note that they also appear to be the same model sold by Orion Telescopes.

There's a bit of a story itself behind this... the short version is that these 90s were a replacement for a pair of the 45 degree version that I sent back for a collimation check ( I was only successful getting images to merge at low power) and some debris visible in the prism turret. It turns out the debris was actually a chip. I was offered a significant discount or a replacement when the next shipment arrived. Since I opted for the replacement I asked if I could upgrade for the $100 retail price difference - which they allowed me to do.

After months of delay - all of which was totally out of Garrett Optical's control and with which I really didn't mind since it was cold and snowy here in Wisconsin, the 90s arrived 3/17 via FedEx Ground. I have to wonder sometimes what happens behind the scenes when a box is plastered with white on red labels stating "Delicate Instruments - Handle With Care" on the outside. Can't help but think its kind of like walking around with "Kick Me" sign stuck on your back!? But the box appeared in good shape, no better or worse than the average box I typically get delivered from them.

The binos themselves were inside their own storage case, which was supported inside the shipping box by a couple inches of foam all the way around.

Out of the box the binos appeared to cosmetically perfect - no scratches on the paint, lenses were clean. The tubes appeared clean with no debris or casting flaws. For some reason they weren't quite as sexy looking as the 45 degree version - I guess the lines were just not as curvy?!

Of course when you get a replacement something the first thing one does is check to see if its any better than the something being replaced. So I took particular attention to the view down the focusers. There it was, bigger even than last time - a chip in one of the prisms in the right side turret. It was out on the edge and I did need to look quite a bit off axis to see it so it really wasn't in the optical path - but still, it shouldn't be there. One other item to note, when looking down the focusers of the 45's there was some pretty apparent cutoff caused by the edges of the prisms - the 90s appeared to be better in that respect (appearances aren't everything).

That evening after work I mounted them on the tripod - I figured even though I'd already decided this pair was going back, I might as well take them for a test drive while I had them.

The self centering focusers are a vast improvement over the o-rings of the 45s (the new 45s apparently now have a similar focuser). The self centering focusers are still going to present problems with any EPs with the safety/security undercuts. My non-OEM EPs are a pair of Smart Astronomy Extra Flat 19mm EPs - fortunately the barrels can be unscrewed and reversed and they worked find in the new style focusers. I placed the OEM EPs into the binos and pointed them down the street about a 1000 feet to a for sale sign on the neighbors yard. The focuser on the left tube was quite stiff to turn compared to the right. What was really nice was the IPD adjustment, much nicer than grabbing the turrets on the 45s and moving them by hand. This screw adjustment feature for the IPD was one of the reasons I opted to replace the 45s with the 90s since I had liked using the 45s during our clubs public viewing sessions last summer, but constantly moved the binos every time I went to adjust the IPD for the different viewers.

After focusing each EP I opened both eyes and.... hmm.... this can't be... double images - one on top of the other, just slighty. At this point I tried all the tricks I did with the 45's such as reseating each EP, rotating one EP, different EPs. All the results were the same - these binos were not collimated! I ended up loosening the right EP holder, making it just loose enough that I could push on the top edge of the EP and tip its position in the focuser. Pushing the right EP slightly forward did the trick - one single image when looking through both eyes.

Again I was starting to wonder if the collimation issue was really just me. I had emphasized and re-emphasized in emails with Garrett Optical during the wait that I was in no big hurry and wouldn't even mind a further delay if the binos could be check for collimation up to 70x. I brought in a couple other people to look through them. They both thought the view was nice and didn't mention anything about a double image. Then I loosed the EP holder had them push the right EP slightly forward while looking through again - then they said "Wow" that's a lot better! Neither had realized how bad it was on their first look.

I sent an email to Garrett Optical that night calling out the chipped prism and the collimation issue. TOS prevents me from including the reply I received the next day so all I can say is that I was shocked. I sent a reply after thinking about it for a day and telling them them that given issues with collimation and chipped prisms I would just prefer to have a refund. A few hours later I received an email with a pre-paid shipping label. The final out come is TBD.

I didn't get them to FedEx before they closed on Friday so I will have drop them off on Monday. In the meantime I took the opportunity to re-do the flashlight aperture test. I had initially done this on the second night and conferred the results with a few other members on the binoculars forum - they were so.. well.. shocking.

This afternoon I set up my test environment again. I mounted the binos on my large Bogen tripod. I took another tripod and secured a newly purchased Coleman MAX 110 lumen LED flashlight. I printed off (and verified) a paper cm ruler and taped it across the the front the left tube. In front of that I placed a digital camera to record the image of the light cone projected onto the paper. I found that the largest diameter cone projected was with the focuser screwed all the way in/down - so I went with that. I took 2 second exposures with the flashlight at distances of 2cm, 10cm, 20cm, 30 cm and 55cm (the highest I could go) above the EP. The 2cm distance gave the widest diameter cone. The cone dropped off considerably at 10cm and was consistent at all the other distances. I believe the 2cm distance is too close because if you look closely you can see several light cones being projected on the the paper - the smallest cone is consistent with the cones projected with the light source at the 20/30/55cm distances.

Rather than stating the obvious, I'll post the pictures and leave the assessment as an exercise for my fellow forum readers...

It would probably be a really good idea if someone else could validate my testing method as well test a different pair of 90s.

#16 mtb54703

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Posted 21 March 2010 - 09:48 PM

The binos themselves.

The distance from the front of the tubes (dew shields retracted) to the gold ring just in front of the lower prism housing is 12.125". I measured the outside of the edge of the objective to 1.625" from the front edge of the tube (again with the dew shields retracted).

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#17 mtb54703

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Posted 21 March 2010 - 09:49 PM

Down the focusers...

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#18 mtb54703

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Posted 21 March 2010 - 09:50 PM

Almost straight down the right focuser...

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#19 mtb54703

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Posted 21 March 2010 - 09:51 PM

Down one tube...

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#20 mtb54703

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Posted 21 March 2010 - 09:52 PM

From the front...

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#21 mtb54703

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Posted 21 March 2010 - 09:53 PM

Dew shields extended...

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#22 mtb54703

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Posted 21 March 2010 - 09:55 PM

Test setup for the aperture test...

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#23 mtb54703

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Posted 21 March 2010 - 09:56 PM

Ruler validation...

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#24 mtb54703

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Posted 21 March 2010 - 09:56 PM

Light cone with light source 2cm above EP...

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#25 mtb54703

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Posted 21 March 2010 - 09:57 PM

Light cone with light source 10cm above EP...

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