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Denk II Super System or Baader Mark V For TEC140?

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#1 10gauge

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Posted 15 December 2011 - 08:43 PM

I am looking for a top notch binoviewer with no color aberrations, no false color, and no lossy optics whatsoever! I am trying to decide between the Denk II Super System with PowerxSwitch and the Baader Mark V binoviewer for a TEC140. The back focus is 170mm on the TEC140. I keep hearing in threads that the Denk II PowerxSwitch has a little color aberration compared to the Baader Mark V.

I just found out that A-P is out of the Baader T-2 prism diagonal in the Baader Mark V kit, so they'll be shipping the Baader Mark V with a mirror dielectric diagonal. They won't get the prism diagonal for another 5 months. Isn't the mirror diagonal bad for color aberration when compared with a prism diagonal?...

What are people using with 5-6in premium refractors like the TEC140?...

Thanks,
George

#2 BWAZ

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Posted 15 December 2011 - 08:57 PM

Where did you get the info the Mark V now comes with a mirror diag instead of the Zeiss T-2 one?

As for the choice, I'm somewhat biased since I've been using my Mark V for the last three years and am still being impressed by its superb optical quality. I've used the Denk II as well, and greatly appreciated its convenient powerswitch system while the Mark V lacks. But the versatility of the T-2 system partially offset the inconvenience of changing barlow/glasspath for different magnification factor. In the end, I still prefer the optical quality offered by Mark V and have learned to "ignore" the Powerswitch offered by Denk. ;)

BTW, someone in the forum has succeeded combining the Powerswtich and the Mark V in the past and I believe that's a great idea to have the best from both. You may wanna look for that.

#3 10gauge

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Posted 15 December 2011 - 10:00 PM

Thanks BWAZ, I called A-P today to inquire about the Baader Mark V. Rep said that Roland Christen tested the bino with the Baader mirror diagonal, and he reported no issues with color. But, I still think that a prism will provide the ideal color correction.

I know, the PowerxSwitch is so convenient, but I am with you on the optical quality. I'll have to search for the mating of the Baader Mark V and PowerxSwitch - that's brilliant! Besides, I am still waiting to have my scope built - by the time it's done in the Spring, A-P will have the prism diagonal back in stock... I'll have to wait to get the Mark V. In the meantime, save money for an Atlas mount, and be on the look out for EP sales...

#4 Tamiji Homma

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Posted 15 December 2011 - 10:23 PM

Hi George,

I have both Baader T-2 mirror and prism diagonals that I use with MarkV. It is extremely hard to see the difference between those diagonals with slow scope (f/7+). IMHO, only benefit of prism diagonal is shorter lightpath so that it increases a chance to come to focus to infinity than system with mirror diagonal. It is sometimes that a few millimeters make difference :)

I use mirror diagonal when I use MarkV with faster scope (f/5.5), though.

Regarding DenkII v.s. MarkV, if you need just one setup, go for MarkV. I observe with multiple scopes often so I have several binoviewer setups, MarkV, DenkII, and Bino Vue.

They are all good. I find my eyes are the weakest element of the optical chain.

CN fellow Sergio (CrazyCuban) posted PowerSwitch and Mark integration here.

http://www.cloudynig...hp?item_id=2521

If you have enough backfocus, you can use Denk R1 diagonal with PowerSwitch along with 2" nosepiece + MarkV. You can have someone make custom adapter like Sergio did, you have more options to explore.

I have Starlight Instruments made T-2 adapter for DenkII so that I can enjoy T-2 modular parts with DenkII, too.

Here is a photo, from left to right, DenkII, MarkV, and Bino Vue with T-2 Prism diagonal attached.

Posted Image

Tammy

#5 johnnyha

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Posted 15 December 2011 - 11:02 PM

If the replacement diagonal is the 2" AP Maxbright and you don't have one already then that is a really good trade-off. I love the T-2 prism but I often have to use a mirror diagonal anyway since I like to connect the Mark V binos to my 2" 2X Powermate with a T-ring connector.

#6 mgwhittle

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Posted 15 December 2011 - 11:41 PM

Hi George,

I have both Baader T-2 mirror and prism diagonals that I use with MarkV. It is extremely hard to see the difference between those diagonals with slow scope (f/7+). IMHO, only benefit of prism diagonal is shorter lightpath so that it increases a chance to come to focus to infinity than system with mirror diagonal. It is sometimes that a few millimeters make difference :)

I use mirror diagonal when I use MarkV with faster scope (f/5.5), though.

Regarding DenkII v.s. MarkV, if you need just one setup, go for MarkV. I observe with multiple scopes often so I have several binoviewer setups, MarkV, DenkII, and Bino Vue.

They are all good. I find my eyes are the weakest element of the optical chain.

CN fellow Sergio (CrazyCuban) posted PowerSwitch and Mark integration here.

http://www.cloudynig...hp?item_id=2521

If you have enough backfocus, you can use Denk R1 diagonal with PowerSwitch along with 2" nosepiece + MarkV. You can have someone make custom adapter like Sergio did, you have more options to explore.

I have Starlight Instruments made T-2 adapter for DenkII so that I can enjoy T-2 modular parts with DenkII, too.

Here is a photo, from left to right, DenkII, MarkV, and Bino Vue with T-2 Prism diagonal attached.

Posted Image

Tammy


Tammy,

Does the TV Bino View attach directly to the T-2 or is there some kind of adapter ring?

Thanks!

Mark

#7 Tamiji Homma

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Posted 16 December 2011 - 12:37 AM

Hi Mark,

If you remove Bino Vue 1.25" nosepiece, bottom of Bino Vue is T-thread female ring. You can directly attach (screw) Bino Vue on top of Baader T-2 diagonal.

Here is photo Bino Vue is detached from T-2 Prism Star Diagonal.

Posted Image

Tammy

#8 mgwhittle

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Posted 16 December 2011 - 12:57 AM

Thanks Tammy, I'm trying to narrow down a system and this information helps. I do like the T-2 system and want the bino viewer I get to integrate in it like you have done.

Mark

#9 suburbanskies

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Posted 16 December 2011 - 10:42 AM

Isn't the mirror diagonal bad for color aberration when compared with a prism?


A technical note if you're interested...by their very nature, prisms add color error. Mirrors do not. A 1.25x color corrector is included with the AP/Baader MarkV to correct for the color error caused by the prisms inside the binoviewer and probably the T2 prism diagonal, too. You might be correct, in the following way: using a mirror may result in color aberration if the 1.25x corrector overcorrects for color in the absence of the T2 prism.

In any case, this isn't of practical importance according to what you heard. :) AP has tested the Mark V with the mirror diagonal and found no practical effect. I'm sure Roland's eyes are much better than many of his customers!

Mark

#10 10gauge

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Posted 17 December 2011 - 11:14 AM

Thanks Tammy for the informative pics and descriptions. According to Yuri, the f/7 TEC140 has 170mm of back focus. If a mirror diagonal can be used without color aberration in a f/7 scope, is that with or without the 1.25X corrector in place?...

I was planning to get the A-P Maxbright mirror diagonal. I wonder if that can be used with the Baader Mark V?...

I am not sure how much distance is required for the Mark V to come into focus, however, I also like the idea of having a shorter light path of a prism diagonal because I am not a fan of having the focuser in an over-extended position with a bino + 2EPs attached.

As far as Binos go, it seems the Baader Mark V is the way to go, plus it does give 2mm extra aperture with the borderline EPs having larger field stop diameters. However, the lack of practical magnification switching is a huge detriment when compared with the Denk II Super System.

Thanks for the Frankenbino link. Short of buying a Denk PowerxSwitch, I am not exactly sure what are the requirements for the custom ring to mate the Mark V and the PowerxSwitch. I may have to contact Sergio. I wonder if the Mark V + PowerxSwitch binocombo vignettes at its widest position?...

Thanks everyone!
George

#11 Paul G

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Posted 17 December 2011 - 12:24 PM

I was planning to get the A-P Maxbright mirror diagonal. I wonder if that can be used with the Baader Mark V?....


That combination works fine in my refractors.

As far as Binos go, it seems the Baader Mark V is the way to go, plus it does give 2mm extra aperture with the borderline EPs having larger field stop diameters. However, the lack of practical magnification switching is a huge detriment when compared with the Denk II Super System.


I just change eyepieces when I want to change magnification, occasionally use the short section of the AP Barcon. In the magazine review of the denk system, didn't the powerswitch introduce some optical aberrations?

#12 Tamiji Homma

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Posted 17 December 2011 - 12:59 PM

Hi George,

If TEC 140 has only 170mm backfocus, it won't come to focus to infinity with AP MaxBright + AP16T + Baader Quick Changer + 1.25x GPC + MarkV unfortunately.

I have TMB 130SS f/7, whose backfocus is about 249mm.

Here is how much left on FT3545 focuser with different configuration when it comes to focus to infinity.

5mm: AP MaxBright -> AP16T -> Baader Quick Changer + 1.25x GPC + MarkV + Nikon NAV SW 14
69.5mm: Baader T2 Prism Star Diagonal + Baader Quick Changer + 1.25x GPC + MarkV + Nikon NAV SW 14.

System with Baader T2 Prism Star diagonal is about 64.5mm shorter lightpath than one with AP MaxBright.

When you go high power, you would probably use Barlow lens (ex: AP BARCON). If you place BARCON in front of diagonal, you should be able to come to focus with AP MaxBright. Actually, I would recommend the configuration (AP BARCON) when you go high power rather than short focal length eyepiece.

Tammy

#13 10gauge

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Posted 17 December 2011 - 01:23 PM

Thanks, Gus. Since I am going to have the Maxbright 2" mirror diagonal, I am glad that it will work with the Mark V. When A-P gets the Mark V back in stock with the Baader prism diagonal in April 2012, I'll have 2 types of diagonals to fool around with too!

Yes, I remember on a few threads that there was some color aberration with the Denk II PowerxSwitch. You're right, for the cost of buying a PowerxSwitch, one can simply double up on current EPs. There seems to be all kinds of variations as to before/middle/after placement of the Barcon to achieve a myriad of magnifications.

Thanks!

#14 10gauge

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Posted 17 December 2011 - 02:40 PM

Thank you Tammy for the heads up! The info about the TEC140 back focus was from the TEC forum dated ~2003-2004. It might be outdated in the sense that TEC may have changed the spec with their later generations and new TEC focuser after all the chatter at the time. TEC doesn't use the FT3545 focuser anymore, they've come up with a new beefier "TEC focuser" which has 3.2" travel (1/4" less than the FT). I better find out what the deal is with TEC's back focus. If I remember from a photo on CN, I think mark8888 uses a Baader Mark V bino on the new TEC140.

64.5mm difference in back focus between prism/diagonal is huge! What are the back focus requirements for the configurations:

1. Maxbright -> AP16T -> Baader Quick Changer ->1.25x GPC -> Mark V -> EP
2. T2 Prism -> Baader Quick Changer -> 1.25x GPC -> Mark V -> EP
3. Barcon -> T2 Prism -> Baader Quick Changer -> Mark V -> EP


Here's a clip from Astro-Physics site:
Backfocus (In-travel) Requirements

Backfocus (also referred to as in-travel) is the difference between where the light focuses and the back of the focuser needs to be. The back focus requirements will vary depending upon your configuration. Please note that this viewer may not reach focus with some instruments, including some earlier models of our refractors. Determine the back focus of your instrument by measuring the distance from the 2" opening of your scope to the focus point.

Binoviewer with 1.25x Compensator, 2" Nosepiece and Convertible Barlow - needs 0.6" in-travel
Binoviewer with 1.25x Compensator, Mirror or Prism Diagonal and Convertible Barlow - needs 1.8" in-travel
Binoviewer with 1.25x Compensator and 2" Nosepiece - needs 3.5" in-travel
Binoviewer with 1.25x Compensator and Mirror or Prism Diagonal - needs 4.5" in-travel

Binoviewer with 1.70x Compensator, 2" Nosepiece and Convertible Barlow - needs 0.7" out-travel
Binoviewer with 1.70x Compensator, Mirror or Prism Diagonal and Convertible Barlow - needs 0.55 " in-travel
Binoviewer with 1.70x Compensator and 2" Nosepiece - needs 2.25" in-travel
Binoviewer with 1.70x Compensator and Mirror or Prism Diagonal - needs 3.25" in-travel

If you do not use the 1.25x compensator, the backfocus is increased by 1.25x in all configurations
Binoviewer with 2" Nosepiece and Convertible Barlow - needs 0.9" in-travel
Binoviewer with Mirror or Prism Diagonal and Convertible Barlow - needs 2.25" in-travel
Binoviewer with 2" Nosepiece - needs 4.4" in-travel
Binoviewer with Mirror or Prism Diagonal - needs 5.6" in-travel.


According to the A-P chart, I can't use the Baader Mark V with any of the combinations that exceed 3.2" in-travel?... That's a majority of the better scenarios with the least amount of glass in the path!


BTW, how is your TMB130SS working out for you?... Any chromatic aberration, false color?... After seeing a considerable amount of CA visible on an ES127, I knew I'd want a better scope with less aberration and that's when I started to look at the TMB130SS and TEC140 scopes. Heck, even my Canon L lenses drive me crazy with CA... I wish I knew about the $700 discount on the TMB130SS at Astronomics earlier this year. Oh well, both still seem the best values at their respective class: 5in and 5.5in.

Thanks,
George

#15 Tamiji Homma

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Posted 17 December 2011 - 07:53 PM

Hi George,

I would redirect you to old thread to discuss various backfocus measurement thread Link.

Regarding TMB 130SS f/7 optical performance, I don't have any complain :)
The color correction is as good as TSA102S f/8 or TMB 152 f/7.9 to my eye(s) using binoviewer.

Tammy

#16 crazyqban

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Posted 17 December 2011 - 08:48 PM

Hi George, to use the Denk PowerSwitch with the Mark V I had Ashley fron Precise Parts make a connector that would allow both systems to work together. It is a simple adapter and if you are interested he could make one for you. He is a fellow member of the Southern Cross Astronomical Society so if you are interested I could take mine to his shop and he would be able to make one just like it. However, after using the Frankenbino for a while, I noticed that the images were slightly dimmer when compared to the images using the Baader 1.7X Newtonian Glasspath Compensator. The downside to the 1.7X GPC is that the magnification is rather high for my liking. This sent me on a quest to find an adapter that would provide the same wide filed as the Denk PowerSwitch but with the same optical quality of the Baader 1.7X GPC. Enter the Siebert Optics 2OCA13. With this adapter I have comparable optical quality to the Baader 1.7X GPC and a slightly less magnification factor of the Denk Powerswitch system. So far I am very happy with this etup. I thought that I would miss the PowerSwitch but that has not really happened. I did, however, acquire a few more pairs of eyepieces. Before I was only using a pair of 24 Panoptics and 16 T5 Naglers and now I have those plus 7, 9, 11 & 13 T6 Naglers. I would like to try pairs of 8mm & 12mm Delos when they become available. If I like them, I might just replace the T6s with those.

#17 crazyqban

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Posted 17 December 2011 - 08:49 PM

PS, Frankenbino is still alive and well. My friend is using my PowerSwitch and the custom adapter with his Mark Vs.

#18 10gauge

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Posted 19 December 2011 - 10:44 PM

Hello Tammy, thank you for the link as it explains a lot about the various scenarios with the Barcon and OCS in relation to the back focus. I am not sure if the back focus on the TEC140 is still 170mm as that info was from an old thread dated 2003-2004. I still haven't heard anything from the TEC site. I was initially confused by the "back focus" is measured: Whether it starts from the collet where the diagonal attaches or from the focuser/OTA attachement?... Your diagrams in the link are excellent and your knowledge is keen and thorough!

Sergio, thank you for relaying the information about Ashley from Precise Parts and the use of the Siebert Optics 2OCA13. Well, if you want the Delos, order them before January 1st as Televue is increasing their prices...

Thanks again for the great advice!
George

#19 mark8888

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Posted 20 December 2011 - 12:59 AM

Before I was only using a pair of 24 Panoptics and 16 T5 Naglers and now I have those plus 7, 9, 11 & 13 T6 Naglers. I would like to try pairs of 8mm & 12mm Delos when they become available. If I like them, I might just replace the T6s with those.


I'm also using the 24pans and 16T5, and I have the 10 Delos and the 9T6. I use them all with the Mark V binoviewer... I definitely find myself using the 10 Delos more than the 9T6 (though the 9T6 has its own advantages). So I would agree with you... bring on more Delos lengths!!

George I can tell you based on my experience that the Mark V and the TEC 140 work very well together. As per Tammy's very helpful suggestion I bought the 2" extension tube EXTTLR from Astro-Physics to enable the scope to come to focus at some higher magnifications (while using a barlow or higher mag GPC's).

#20 10gauge

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Posted 20 December 2011 - 11:16 PM

Thanks Mark, I am glad you chimed in - I was going to send you a PM. I couldn't pin it down, but something seemed intuitively wrong with such a short back focus distance of 170mm on the TEC140. Thank you (and Tammy) for suggesting the 2" extension tube. I mapped out the possible magnifications of your EP, GPC, and Barlows combinations.

..................Mag.....w/1.25X.....w/1.7X.....w/Barcon
24 Panoptic...41X........51X...........69X..........81X
16T5............61X........76X..........104X........122X
10 Delos.......98X.......123X..........167X........196X
9T6............109X.......136X.........185X.........218X

With your experience:
- In which of these scenarios do you need the 2" extension tube?...
- Does the GPC reduce the focus distance by its correction factor?...
- What's the maximum magnification before the image breaks up or is too dim?...

Thank you!
George

#21 mark8888

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Posted 21 December 2011 - 09:48 AM

Thanks Mark, I am glad you chimed in - I was going to send you a PM. I couldn't pin it down, but something seemed intuitively wrong with such a short back focus distance of 170mm on the TEC140. Thank you (and Tammy) for suggesting the 2" extension tube. I mapped out the possible magnifications of your EP, GPC, and Barlows combinations.

..................Mag.....w/1.25X.....w/1.7X.....w/Barcon
24 Panoptic...41X........51X...........69X..........81X
16T5............61X........76X..........104X........122X
10 Delos.......98X.......123X..........167X........196X
9T6............109X.......136X.........185X.........218X

With your experience:
- In which of these scenarios do you need the 2" extension tube?...
- Does the GPC reduce the focus distance by its correction factor?...
- What's the maximum magnification before the image breaks up or is too dim?...

Thank you!
George


Greetings.

>>- In which of these scenarios do you need the 2" extension tube?...

Well... all the eyepieces listed are parfocal or very close to parfocal, so the same answers apply to all of them. Conveniently.
I've found that with the 1.25x GPC or the 1.7x GPC, they don't need the extension tube.
With the BARCON barlow, they do.

>>- Does the GPC reduce the focus distance by its correction factor?...

Not sure how to precisely answer this... I'm sure someone else would. Anyway, with a higher correction factor, the focuser needs to be extended more. With the 1.7x GPC the focuser needs to be extended about 65mm (well, it reads "65" on the focuser, anyway...) to come to focus.

>>- What's the maximum magnification before the image breaks up or is too dim?...

I use the binoviewer 100% of the time... so monoviewing answers might be very different from my experience. I'm always using a GPC, whether or not I'm also using a barlow... hmmm...

According the the AP website, the BARCON gives you:
2.4x before the Baader Planetarium Binocular Viewer (threaded directly into the prism diagonal)
3.2x before the Baader Planetarium Binocular Viewer used with the extension

What I'm wondering is, if I'm using the configuration of diagonal-AP16T-BARCON... so the AP16T is threaded into the diagonal, the barcon is threaded into the AP16T, and both the AP16T and BARCON are nestled inside the 2 inch extension tube... is that 3.2x, or something in between 2.4x and 3.2x? Not sure what AP is referring to by "the extension". Hmm...

Well lets go with the 2.4x, I've definitely used that configuration with success.

OK, so I can say with certainty that I've been able, with good seeing, to get a nice sharp image of Jupiter coming in and out of view at 294x (10mm Delos, 1.25X GPC + BARCON threaded directly into the diagonal) on more than one occasion. For pretty brief moments.

I was able to see Mars at something closer to 400x clearly on one night of very good seeing. So, that was the highest magnification I've been able to sucessfully use, and only on Mars.

I'm not using a driven mount, so maybe if I were the answer would be different. But I'm gonna say 250-300x, with the Mark V, can be OK with good/very seeing, but any higher than that and it almost always starts to break down. The moon starts to look washed out, Jupiter gets blurry.

I like Jupiter a lot, with good seeing, using the 16T5, 1.25 corrector, and the BARCON... which gives 183x. That seems to be a great combination for me, and the seeing usually supports it eventually, so it's not just really brief moments of clarity but it can be more extended. I'd love to compare a 16mm Delos to the 16T5. The eye relief in the 16T5 is pretty brutal, but I seem to always be using it. A lot of people mention that the 16T5 is exceptionally "sharp", I wonder if I'm experiencing that, and a 16mm Delos wouldn't match it?

Anyway, this has been my experience. Like you I'd also be interested to hear about other peoples experiences with the TEC 140 and Mark V binoviewer, with the same or similar eyepieces/magnifications, to see if they are similar are radically different from mine! I'm no pro so the more answers you get the better...



#22 10gauge

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Posted 22 December 2011 - 12:06 AM

Thank you, Mark, for sharing your experience with the Mark V and the Tec140! :waytogo:
Fantastic response to an otherwise tricky subject of binoviewers. I wasn't sure if I'd be able to reach focus with certain EPs, GPC, barcon combinations. It's interesting to see that you can use the GPC AND Barcon in the light chain, as opposed to just using a GPC OR a Barcon. It does give you more options. I am not sure about using a 2 GPCs in the chain as it may "over-correct" the color.

The Barcon includes the ADA202 1.75" Extension. Do you use it?... Would I still need the EXTTLR 3.6" Extension?...

When I get everything, I'd like to chart ALL the possible configurations in order of increasing magnification in the total chain:

Focuser--ADA202/EXTTLR--Barcon--AP16T--T2--Quick Changer--1.25X--MarkV--EP

Otherwise it can be overwhelming to decide which way to go in the dark...

Which would be better having the 2.6X GPC or a Barcon in 2.4X configuration?... It seems redundant at such a close magnification range. I may not buy the 2.6X GPC. However, In place of the Barcon, I am also wondering if the 2.6X GPC can reach focus without the extender?...

Wow, you can get 250-300X under good seeing in a bino? I'll be very content 180-200X on Jupiter! I am thinking of the following EP for bino use:
24 Panoptic, XW10 or Delos 10 - both seem to have generous eye relief. I am definitely getting the Ethos 13... I am tempted to bino it since it has a desirable exit pupil on the TEC140... I'll wait to see first how everything comes together and get an idea of how things actually will look with a few EPs to start...

BTW, I've never owned a telescope. Hopefully, that will change next spring. I am starting from scratch: GoTo and alt-az mount, scope, EPs, accessories, etc. This is a huge purchase for me with a proportionately large learning curve. That's why I am trying to resolve any questions before I get the TEC140.
When I joined CN one year ago, I didn't know sh-- from shampoo about telescopes. Most of the time has been spent trying to ask the right questions and develop a sense of intuition. I am fast learner, but the CN community has been a great mentor! :bow: I can't wait to actually own a TEC140 and start gaining field experience instead conceptualizing everything in the abstract....

Thanks again,
George

#23 Tamiji Homma

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Posted 22 December 2011 - 11:13 AM

Hi George,

I attached Barlow factor measurement log that I've been doing for several years, various Barlow lens, lens placement, binoviewer, eyepiece combination.

They are all measured with refractor.

You may find it useful.

Tammy

Attached Files



#24 mark8888

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Posted 22 December 2011 - 12:12 PM

Wow Tammy that is such an amazing and useful chart!

Lots of interesting stuff to respond to, George... will do when I get a chance! I actually have the 2.6x GPC so when I can I'll play around with it for a while and see what's up. I've used it, but not much. I'm pretty sure it did require the extender but not sure... will confirm...

#25 10gauge

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Posted 22 December 2011 - 11:29 PM

Bravo Tammy! :bow: Thank you very much! You are a true ambassador to this hobby. This is the kind of chart I was talking about yesterday. Your attention to detail is extraordinary and thorough. This is a tremendous benefit to visualize accessories, magnification, and all possible configurations with various refractors.

Thanks Mark on the 2.6X GPC. I guess after a certain magnification, the extender is necessary to account for the increase in focal length. I think I might get by with just the 1.25XG GPC and Barcon in the beginning. I'll test it first after I get the scope. I might get a second bino pair, like a XW10 or Delos-10, after I try out all the possibilities with the 24 Panoptic... I am still debating whether to get the 24 or 19 Panoptic?... I might just plug both into Tammy's chart for the intended configuration and go from there...

Mark and Tammy, thanks for the help and advice.
Best wishes for the upcoming holidays and New Year!

George






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