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Garrett 100mm f5.3 45 BT first light

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#1 beachchairbill

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Posted 19 December 2008 - 09:49 PM

Hi everyone and Happy Holidays,

I understand that many of you have been anxiously awaiting comments on the Garrett BT first light experience. Here are my comments and please understand that I did this at 12pm last night from my 3rd fl apt. kitchen window. At least it was warm, however, there was a very heavy cloud cover and the only thing viewable was the moon.

Did the BT work at night - without question once I removed the lens covers from the BT. - oops. First I used the 20x eyepieces as two set were supplied with the purchase. The first thing that I noted was longer than normal eyecups. So long that you could fold them twice before reaching the end of the exit eye lens. I hope I'm saying this right. After focusing each eyepiece, I was able to experience an image of the moon surface that I had not experienced before and that was exciting. I then changed to the 40x eyepieces and found no chalange removing the first set. On very cold nights I wonder, as it is a very thght fit? At that time, refocus was necessary but not a problem. The image of the moon was still sharp and a little larger. I did find that when the left eyecup was folded down it would pop right back up again. Therefore, I held it down with my finger - new I guess?

Did the Tel Vue Ethos 8mm come to focus - you bet it did and my left eye kept saying let me see, let me see. Under the aforementioned conditions - WOW

Thank the lord that Santa did not come by the moon yet - wish full thinking.

EDZ and Erik please help me with your comments on how I can improve this review for everyone.

Thanks

Beachchairbill

#2 Erik D

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Posted 19 December 2008 - 11:54 PM

BB,

Happy Holidays to you too.

One reason for my keen interest in this model is the ability to reach higher power with standard 1.25 inch EP. (My current high power set for the Miyauchii Saturn III is 54X) I also have an interest in using them as high power twin spotting scopes. The GT 100 is nearly a foot shorter, should be much easier to handle.

I would like to know how is the CA level with TV 8mm/66X in the day time. Is purple fringing acceptable? Annoying? How is the color fidelity? If possible compare the view with a pair of 15X70, 20X80 or 25X100 binoculars. ( for me purple fringing is annoying in my 25X100s in the day time, not acceptable with my 54X100 Miyas)


I believe standard EPs are 23mm/23X and 13mm/41 X. How is the edge performance? Sharp to 66% from center? Useable to 80%? Do you have other EPs you can try in the mono mode to compare?

That's what I can think of right now. I am sure I'll have others to add later...

ERik D

#3 beachchairbill

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Posted 20 December 2008 - 01:30 AM

ERik D,

Thanks for the quick response and I will work on your request over the next several days. Right now we are covered with snow and ice her in Brooklyn, NY with temp to hit only 28 degrees today. I will take my BT to the 57th Street pier and look at the Statue of Liberty as a test. This should give me good results.

Thanks

Beachchairbill - I like BB it sure beats BS (Bill Shea)

#4 Jitou

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Posted 20 December 2008 - 09:22 AM

beachchairbill,

Your first impressions seem very promising. We're eager to hear about the rest whenever you can do more testing. The weather is very bad here too.

Thank you,

Jitou

#5 boydd

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Posted 20 December 2008 - 11:30 AM

BB,

If we all use the company desination for bino models no confusion can occur. BT is Oberwerk, GT is Garrett Optical, BR is Miyauchi. Therefore, BT 100/45 is not a GT 100/45. I am guilty of using GO instead of GT and will correct this.

Regarding visual reviews. You must use the stock EP in a scope known for visual acuity to evaluate the EP. You must use a premium EP with known visual acuity to evaluate the bino. Only then can you evaluate the stock EP and bino together. This is the scientific process. Personally I give the stock EP's away. I use only premium TV EP's because I need the additional dioptrix. I have adopted a dioptrix to my twin arm Sky Window setup and it works well. A lot of work, but no away around this with fixed EP binos. The TV EP's and dioptrix are plug and play.

Anyone who wants to see the BT 120/45 and the GT 100/45 on a twin arm mount is welcome to PM me and set up an appointment. I live in Grafton, West Virginia.

Dave Boyd

#6 milt

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Posted 20 December 2008 - 01:04 PM

I would like to know how is the CA level with TV 8mm/66X in the day time. Is purple fringing acceptable? Annoying?



The nighttime equivalent to what Erik is asking would be to point the bino at Sirius - and this can check for several other things as well.

Purple fringing is actually to be expected in a fast achromat, so I wouldn't worry about it providing that when centered in the field at 66x the white core of Sirius focuses to a tight ball without ambiguity as to what best focus is. In other words you shouldn't have to hunt around for best focus, you should know without a doubt when you're there.

When Sirius is defocused in the field center, look for a round pattern on both sides of focus. If you should see the pattern stretch slightly in one direction on one side of focus and the orthogonal direction on the other side, then there is astigmatism. This could still be a perfectly good objective but with tilt in the system.

Then move Sirius toward the field edge at low power until it gets softer and see if you can refocus to regain a good image. If you can, it is normal field curvature (edge astigmatism is also normal). Then move Sirius off the field entirely in several different directions. The field should turn black, but often does not... Look for any significant ghosts or reflections.

And then just go look at some DSO's and ENJOY! (after reporting back to us....)

#7 beachchairbill

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Posted 20 December 2008 - 07:13 PM

Erik D,

I just returned from my trip in search of answers to your questions. For this test, I went to the 57th Street pier with ice and snow on the ground and a 15 mile an hour wind comming off the water. The tempature was 28 degrees. Boy was it cold. As you requested, I used several eyepieces in mono mode:

TelVue Ethos 8mm - able to focus - no purple at the edges - looked sharp beyond 80%.

Meade Super PlossL - 40mm - nice - no purple at the edges - good above 80%.

Meadde Super Plossl - 32mm - 26mm - no purple at the edges - 80% or better - nice views

Meade Super Plossl - 6.2mm - no purple at edges - very small pin hole to look through - not one of my favorites to look through.

Please understand that the weather conditions during the test period were cloudy, dark, with no sun. I would like to do this test again in full sun and warmer conditions.

BB

#8 Erik D

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Posted 20 December 2008 - 10:08 PM

BB,

Thanks so much for that. You went above and beyond the call...

It was 24 deg F in central NJ this morning. 23 deg at 9 pm. Didn't get much colder after the sun went down. Not sure why I thought you lived in Southern Cal before. ;-))

Your test sounds very encouraging. I would enjoy using 66X100 twin spotting scopes!

Do repeat the test under full sun when you can. I found purple CA most annoying when I am viewing dark objects (tree branch, black vulture, etc) or white fence against bright sky.

I am not surprised about the pin hole effect with your 6.2 mm S Plossl. Assuming the 6.2 mm Meade is 52 deg, you are getting about 0.6 deg Tfov. Must seem tiny compared to looking thru the 8mm Ethos with 100 deg/1.5 deg Tfov.

ERik D

#9 beachchairbill

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Posted 21 December 2008 - 12:06 AM

ERil D,

No problem and if you can think of any additional test, I will be more than happy to give it a shot.

BB

#10 planet-beaver

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Posted 21 December 2008 - 04:23 PM

Thanks BB for your review. Finally someone is taking their time to write something about the new GT 100/45.

#11 boydd

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Posted 21 December 2008 - 07:52 PM

PB,

Few to no reviews on the BR-141/45/90 or the BT 120/45 either. Sometimes you just bite the bullet and do it. There are never enough reviews to statistically point in a definite direction.

Dave Boyd

#12 milt

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Posted 21 December 2008 - 09:13 PM

There are never enough reviews to statistically point in a definite direction



Dave, you make an excellent point, especially with regard to Chinese manufactured optics. In the past they have earned a reputation for somewhat spotty quality control, so the more different examples of a given model that can be reviewed, the more confident the next buyer can be.

As Kenny said in a different thread, when it's a Pentax model (or Nikon or Fujinon, etc etc) one can be reasonably confident - even with limited reviews. Unfortunately you also pay for that confidence... :(

#13 beachchairbill

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Posted 22 December 2008 - 01:21 AM

Hi everyone,

Here is a problem that you have when you purchase a inter changeable Binocular BT. I now have one of the following Meade Super Plossl 40mm, 32mm, 26mm, 20mm, 15mm, 12.4mm, 9.7mm, 6.4mm as well as the TelVue 8mm Ethos. Do I look to add a duplicate to some of the Meades or add an additional 8mm ethos. If I add the Ethos will it change the balance point? Here we go again with bp. Yes, it is my openion that the 8mm ethos will fit side by side, but not sure about the 13mm. Suggestions

BB

#14 Jitou

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Posted 22 December 2008 - 02:03 AM

boydd,

You're absolutely right, other fair reviews of the BT 120/45 are missing. Personally I am hesitating between the BT 100/45, the BT 120/45 (or whatever name they call it in Europe) and the GO 100/45. Thanks to beachchairbill we have a first on the GO latest model.

Jitou

#15 milt

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Posted 22 December 2008 - 01:11 PM

it is my openion that the 8mm ethos will fit side by side, but not sure about the 13mm. Suggestions



This forum has gone 'round and 'round on this over the years. Having owned a 100ED Binoscope and used several different types of eyepieces, my opinion is that doubling up a Nagler is of marginal value and doubling an Ethos is wasted money.

My reason for this is that when I use my Ethos in my telescope, I find that I have to physically pivot my head to explore the field edges. This is something that cannot be done at a bino without losing the exit pupil on the opposite side.

This may be due to my own facial shape, age, etc, and others may be able to see more of the field with their eyes simultaneously aligned to the exit pupils. But for me I just can't see putting that much money into eyepiece pairs - I would rather put it into the BT objectives and use cheaper ep's.

Milt

#16 KennyJ

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Posted 22 December 2008 - 01:55 PM

< My reason for this is that when I use my Ethos in my telescope, I find that I have to physically pivot my head to explore the field edges. This is something that cannot be done at a bino without losing the exit pupil on the opposite side.

This may be due to my own facial shape, age, etc, and others may be able to see more of the field with their eyes simultaneously aligned to the exit pupils. But for me I just can't see putting that much money into eyepiece pairs - I would rather put it into the BT objectives and use cheaper ep's. >

Very interesting points , and very well put too Milt !

Season's Greetings
Kenny

#17 boydd

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Posted 22 December 2008 - 02:12 PM

Milt,

EdZ mentioned a long time ago he had some problems taking in the entire field on the Ethos. I can see the entire field for all 4 Ethos, dioptrix included. 6, 8, and 13 as well in 1.25" binoculars and binoviewers. I am fortunate as I know others cannot.


I cannot use the whole field on double Panoptic 24's with a dioptrix. Though not made for dioptrix, the adapter ring allows for dioptrix use which works well for some folks.

Unless you are not economically challenged, try before you buy. Obviously star parties are great. Skiesunlimited, Pottstown, PA., in eastern PA, has an entire shelf of premium demo lens. Now that gas is down it is worth a trip if you are within driving distance. Excellent observing area within a 20 minute drive. Call ahead to see if your lens of interest is available.

Double up on anything in life with caution!

"Because it works"
Dave Boyd

#18 Erik D

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Posted 22 December 2008 - 02:12 PM

This forum has gone 'round and 'round on this over the years. Having owned a 100ED Binoscope and used several different types of eyepieces, my opinion is that doubling up a Nagler is of marginal value and doubling an Ethos is wasted money.

Milt


Milt,

Thanks for the reality check. Reminds me of comments posted in another thread after seeing photos of a pair of 13 mm Ethos yet again:

Ethos for binoviewer

I may just order a pair of GT 100s one of these days. If I do, I will be sure to try my friends Pentax XWs in them first before investing in a pair of Naglers or Ethos.

Some of us are in the fortunate position to be able to afford premium optics in this economy. Others may be in different financial situations or have other priorities. Spending $900 for my first pair of 25X100 in 2002 was a major purchase decision, at least psychologically. I know others feel the same way about dropping $1K for a pair of GT 100s. We should avoid creating the impression their equipment is lacking if they do not spend $800-$1,200 for another pair of premium EPs right away.

I enjoy EWA Binoculars very much. My current most used astro gear is a pair of 20X80 LWs with 70+ deg FOV and a pair of vintage 7X35s with 11 deg FOV. Cost: $149 and $25. Spending more doesn't always mean more viewing pleasure.


ERik D

#19 beachchairbill

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Posted 29 September 2010 - 11:20 PM

Steve,

Here is another repot that you can read.

BB

#20 medinabrit

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Posted 30 September 2010 - 06:56 AM

Where is the other repot?

#21 SBrian

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Posted 30 September 2010 - 08:07 AM

Thanks for getting back with me regarding the GBTs, I was really close to purchasing the GBT100, but now I’m not so sure.

I just got back into Astronomy and realize how easy and enjoyable it was using binoculars. Last month I started with an old pair of 10x50s and within a week I order a pair of Celestron 15x70s which was a nice step up. But I quickly realized I was lacking the ability to zoom in and out. So the search for a good pair of Binocular Telescopes began and the CN forum has been a good source of information into this new found passion.

BB with your new found wisdom into the BT 100 are there other Binocular Telescope you wished you had purchased over the GBT100?

Again thanks for the help. I'm located in New Hampshire and know how cold it can be during those winter months.

Best regards,
Steve
Bedford New Hamshire.

#22 beachchairbill

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Posted 30 September 2010 - 03:36 PM

Steve,

You would get a better understanding of my many issues with the GBT if you read my thread called Flashlight Games. It's a wonder that these things still work. Funny that you should ask that qusetion. I started off like you, however instead of the 15x70 Cel I purchased the Canon 15x50IS, which is the best purchase I ever made as I use them almost ever night either by themselves or as a help when looking for star cluster before using the GBT.

My next step up was the GBT then the Oberwerk 20x80 which I also had a problem with and had to return it to them for additional repairs and I'm still not happy with them. This might be my next thread Tinkering With My Oberwerk. I then purchased the Orion 5" Telescope and then the Cel 8" Mirror as some one likes to call it.

I originaly started of wanting to purchase the Miyauchi 77, however, they went out of business and second hand ones are hard to find. Still looking.

If I had to do it all over again I would keep the Canon 15x50IS and look to purchase the Canon 10x42IS and give a serious look at the AMP with inerchangeable eps. I would love to own a 10" 12" or 14" Telescope with binoviewer, however, weight is the problem.

I would not purchase the GBT 100 at this time. I would wait for several positive reports first. Many have said that they are not good for viewing plantes and I tend to agree. When I look at Jupiter and it everchanging moons I want to be closer so that I can see more bands etc. The GBT will not
cut it - Stars yes, planets no.

Beachchairbill

#23 Jawaid I. Abbasi

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Posted 30 September 2010 - 04:51 PM

Steve,
wait and read some reviews about 100mm Binoculars. Ask plenty of question without Hesitation as I did before placing an order.

Nothing is perfect but you want something that has the minimum problem within the Budget and APM is the right choice for me but it may not for you. So, extract names that had used or still using 100mm binoculars and send them a private messege.

#24 GlenM

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Posted 30 September 2010 - 04:53 PM

Hi Beachchair,

We both bought the GBT's for widefield viewing :grin:

It looks as though I'm the only one who received a pair that was any good ;)

#25 SBrian

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Posted 30 September 2010 - 07:48 PM

Thanks guys for the help… it sounds like a *BLEEP* shoot! :) I’ve put a call into APM to check for availability of the 100mm. Let’s face it, I just like way they look! I have all ready come to the conclusion that I will need more than one instrument and this is just one tool in the bag of toys. I guess the real question is, are they the best bang for the buck or maybe I should just go with the lower cost 25X100?






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