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Equipment Discussions >> Binoviewers

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Tamiji Homma
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Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: mark8888]
      #4987865 - 12/28/11 12:32 AM

Hi Michael,

The Barlow magnification factor is measured. The published magnification factor such as 1.25x, 1.7x is not absolute The Barlow magnification factor changes when distance between Barlow lens and eyepiece focal plane (where field stop is) changes.

So if you insert extension tube (or AP16T for example) between BARCON and eyepiece, you get higher magnification. The longer distance, the higher magnification you get with Barlow lens in general. There is formula to calculate the factor if you know all the details but it is easier to measure.

When I use 1.25x GPC on MarkV, image is magnified only 1.19x with Delos 10. With 1.7x GPC, I get 1.42x. I simply measure how wide (narrow) you see.

I have a setup (Vixen ED80SF and long ruler on the wall) to measure how many millimeters I see across the field. Say you get 300mm with native eyepiece, then you insert Barlow lens, you get 150mm. You have 2x magnification.

My measurement is also approximate since I am not using a target focused at infinity but I found my measurement reasonably accurate, comparing to drift test (measuring how long it takes for star on/near celestial equator to move from edge to edge of the field).

So now you see what I did, a lot of, hundreds of measurements, I wanted to know what magnification I am getting with particular combination (eyepiece, Barlow lens, extension tube, binoviewer etc) that I use.

In my chart, I used Panoptic 24, Nagler 13T6, and Delos 10.

http://www.televue.com/engine/TV3_page.asp?id=28

Look at this Televue eyepiece specification page, and pay attention to column F. The column F shows where eyepiece field stop is. If the number is same, they are nearly parfocal. They aren't perfectly parfocal but pretty close.

Column F of the three eyepieces shows 0.25 inch. So, the same Barlow factor can apply to all three eyepieces since distance between Barlow lens and eyepiece focal plane is almost same.

Tammy


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #4987914 - 12/28/11 01:55 AM

Hi Tammy,

THANK YOU!! Your explanation really helps a lot... it is amazing that you actually made these calculations by doing actual measurements, hundreds of measurements. When I saw your chart I really thought you had plugged information into some kind of spreadsheet program and those were the results of computer calculations. That's incredible... thank you for sharing the info. with the world, it's really very unique and valuable.

I think I will also eventually do some drift tests, that's a good idea.

I have a follow-up question. As you suggested, I see the column F on the Televue page, and I understand that if 2 eyepieces have the same value, they are nearly parfocal.

Above, you wrote this:
>>When I use 1.25x GPC on MarkV, image is magnified only 1.19x with Delos 10. With 1.7x GPC, I get 1.42x. I simply measure how wide (narrow) you see.

The F value is 0.25 for the Delos. If I want to calulate magnifications for another eyepiece which also has the same value as the Delos (0.25) in column F, for example a 9T6, does that mean that I can use your values of 1.25x GPC=1.19x and 1.7x GPC=1.42x when I do magnification calculations? Because the F value is the same?

Also... the 16T5 has a value of 0.28 in column F. I wonder how I would adjust the calculation to compensate for that. Would the 1.19x and 1.42x be a little higher, a little lower, basically the same?

Anyway thanks so much, this is becoming very understandable... it's amazing how much the actual measurements vary from the stated 1.25 and 1.7. I'm very happy (and I know George is too) to have a chance to accurately know what the mags are...


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: mark8888]
      #4987963 - 12/28/11 05:10 AM

By the way, earlier in this thread in response to George's question:

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

I commented that I was able to get very high magnification on Mars with a good view, close to 400x, but wasn't sure why. So, almost 400x was the max for me, but only on Mars, other objects like Jupiter break up/become dim at much less magnification. As it happens there's an interesting current thread on this topic, other people are having the same experience. Astrojensen gives a great explanation of the phenomenon!

http://www.cloudynights.com/ubbthreads/showflat.php?Cat=0&Board=planets&Number=4985619&fpart=1&PHPSESSID=c4bfb9daccd3963233ae19aad2928a8f

so I thought that as a follow-up I'd post the link here.


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Tamiji Homma
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Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: mark8888]
      #4988884 - 12/28/11 05:47 PM

Quote:

The F value is 0.25 for the Delos. If I want to calulate magnifications for another eyepiece which also has the same value as the Delos (0.25) in column F, for example a 9T6, does that mean that I can use your values of 1.25x GPC=1.19x and 1.7x GPC=1.42x when I do magnification calculations? Because the F value is the same?

Also... the 16T5 has a value of 0.28 in column F. I wonder how I would adjust the calculation to compensate for that. Would the 1.19x and 1.42x be a little higher, a little lower, basically the same?




Hi Michael,

The magnification factor is a function of distance between Barlow lens (GPC) and eyepiece field stop. So I think if F column number is same, they would get the same magnification factor with given GPC/MarkV.

16T5 focal plane is 0.03" closer (inner) than Delos-10, it should get smaller magnification with given GPC/MarkV but it is somewhere margin of error

One measurement that I did with 1.7x GPC/MarkV,
7mm TMB Supermonocentric gets 1.47x
10mm Delos gets 1.42x.

Focal plane of 7mm TMB SM is about 11mm outer than Delos-10 so it gets a little higher magnification. Well, it is not that much, though.

This thread Master Eyepiece Focus Distance Chart has a chart of various eyepiece focal plane distance.

You can go directly to spreadsheet Brandon created.
http://www.cloudynights.com/ubbthreads/download.php?Number=4378893

I found this site about Barlow lens useful.

http://www.astunit.com/tutorials/barlow.htm

Tammy


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #4989137 - 12/28/11 09:02 PM

Thank you very much, I will study all of those links!! And thanks so much for all the clarification of your chart, it's now really clear.
Not only is it vacation time here, but it's been cloudy, so it couldn't be a better time to be posting and reading about all of this.
I'm still amazed at how widely the true information about magnification can vary from the manufacturer's data once you measure it. I don't think I, and maybe a lot of people people reading this, would ever figure out how to make those measurements, so I really feel very lucky that you've shared your data.


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: mark8888]
      #4995812 - 01/01/12 01:57 PM Attachment (40 downloads)

Questions:
1. Should a GPC be used with the BARCON?
2. Do you recommend 8 Ethos for binoviewing?

I've attached the eyepiece and barlow configuration chart for the TEC140.

I am guessing that the magnification for the configuration is:

2.2x? Barcon--AP16T--T2P--QC--MkV--EP.

To calculate this configuration, I used Tammy's measured magnifications for the 2.7x BARCON/1.25xGPC and 3.09x BARCON/1.7xGPC, and divided their respective 1.19x and 1.42x correction factors and got 2.70/1.19 = 2.27 and 3.09/1.42 = 2.18. Since the BARCON placement are all similar, I just averaged the 2 configurations and came up with 2.2x with a 4% margin of error. If so, that's good enough for me.

BTW, for starters, I just ordered a XW3.5, XW5, 13E, and 24 Panoptic pair for binoviewing last night - just before the price increase. I'll try everything then decide whether I'll go with 8, 9, or 10 EPs for binoviewing once the scope arrives in late Spring. Heck, I want to be certain that I am going to like binoviewing in the first place.

I don't have anything yet, but once I get the scope, EPs, mount, diagonal, MarkV, etc., I'll try Tammy's magnification experiment with a tape measure on the wall to see if the above guestimate is correct on the above configuration.
In evaluating all the info furnished by Tammy, it seems that the ratios of exit pupil diameter and barlow magnification for various configurations are directly proportional. In other words 1.19x barlow will reduce the exit pupil diameter of the EP (without barlow) by 1.19x. I am going to try to see if I can calculate the magnification ratios in a different fashion for all the cases by measuring the exit pupil diameters for each case on the TEC140 using an accurate vernier calipers. Here it is:

epd - calculated exit pupil diameter of E.P.
epdb - meausured exit pupil diameter with barlow
barlow mag - barlow mag. factor for particular configuration.

mag = 980/EP.F.L.
epd = 140/mag

Barlow mag = epd (no barlow)/epdb (measured with barlow)

Once again, thank you Tammy and Mark for the great discussion and shared knowledge!
HAPPY NEW YEAR,
George

Edited by 10gauge (01/01/12 02:10 PM)


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #4995887 - 01/01/12 02:47 PM Attachment (49 downloads)

Quote:

Heck, I want to be certain that I am going to like binoviewing in the first place.




I think you'll love it. And the Mark V is amazing. I do 100% of my viewing with the binoviewer. I even do all my (very amateur) afocal photography through the lens of the binoviewer, because I don't want it detached from the scope for even a minute.

It's funny, I also took Tammy's info and expanded it onto charts with other eyepieces. I'll include one chart I got a lot of use out of this week here. Your chart is better and has more information but anyway I think it's convenient. I think our numbers match besides a rounding difference or two.


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Tamiji Homma
Post Laureate
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Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #4995926 - 01/01/12 03:12 PM

Hi George,

Quote:


Questions:
1. Should a GPC be used with the BARCON?





I would recommend to use GPC with MarkV regardless BARCON presence.
Here is old thread to talk about it, Your experience of Baader v Denk II

Quote:

2. Do you recommend 8 Ethos for binoviewing?




It is very hard (or impossible) to take 100 degree AFOV in binoviewer. At least, I can not. So I wouldn't recommend it but I highly recommend it as cyclops mode use

About exit pupil in my chart, it is simply calculated, not measured.
TFOV is also calculated based on measured eyepiece field stop size by this formula:

TFOV (degree) = 57.3 degree * eyepiece_field_stop (mm) / focal_length_of_scope (mm)

57.3 degree ~= 360 degree / (2 * pi)

Exit pupil calculation for TEC 140 f/7 scope.

exit pupil (mm) = aperture (mm) divided by magnification
1mm = 140mm / 140x
2mm = 140mm / 70x

exit pupil (mm) = (focal length of eyepiece in mm) divided by (focal ratio of scope)

2mm = 14mm / 7
1mm = 7mm / 7
0.5mm = 3.5mm / 7

Both formulas are essentially the same thing.

Tammy


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #4996049 - 01/01/12 04:33 PM

Thank you Mark and Tammy! Good link and useful information!

Once I get going, I'll have to try it out myself and see if there's false color or internal reflections with and without the GPC. AND I am going to try the T2 Prism diagonal and the mirror diagonal to see if that makes a difference... If the views are spectacular, I may just screw the whole thing and enjoy my time viewing instead of experimenting.

I think another bino pair besides the 24PO is inevitable. The reason why I was asking about the 8 Ethos was that I was thinking of buying one to use in cyclops mode. Not necessarily for its 100 deg views, I figured since I will have one 8E, why not double up for bino use as well. I figured the 10 Delos might be too close to a 13 Ethos in cyclops mode. I am trying to be a minimalist for EP accumulation - trying to find EPs that will serve cyclops and bino applications, without ending up with redundant F.L... I might just wait for the 8-10mm EP.

On the other magnification spectrum, I wonder if one of the 24 Panoptics will suffice as a wide field cyclops EP?... It might be nice to have a finder EP or a wide field EP. Once I try out the 24PO, I'll see if I need a 31T6 or 35 Panoptic EP for cyclops.

One thing I do have are 4 binoculars. I measured the exit pupil diameters with my calipers and got to within +/- 0.05mm of the published specs.

Yes Tammy, I know your exit pupil diameters are calculated in the previous charts. What I suggesting is instead of measuring the ratios of distances on the wall to get the barlow magnifications, why not physically measure the exit pupil diameters at the EP and take the ratio of the exit pupil diameters to get the relative barlow magnification factor. Two different approaches: Your measurement is taken beyond the objective end, and my measurement would be at the EP end. And hopefully the 2 "ends" will yield similar results.

In any case, this discussion has not only been informative, but has taken the uncertainties and fear out of binoviewers.


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Tamiji Homma
Post Laureate
*****

Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #4996585 - 01/01/12 09:48 PM

Quote:

why not physically measure the exit pupil diameters at the EP and take the ratio of the exit pupil diameters to get the relative barlow magnification factor.




Hi George,

I tried a lot of exit pupil measurements, too. But it works relatively well with multi-millimeter big exit pupil to get reasonable accuracy, something like this one:



I took many shots like above with macro lens and counted pixels in Photoshop to get good accuracy. When you use Barlow lens, exit pupil becomes too small to get good measurement.

It is also becoming cumbersome when you are to measure more than 70 eyepieces, a dozen of Barlow lens, extension tubes, diagonals, 3 different binoviewers etc

I think I spent hundreds of hours(cloudy night/day time of course) over several years to measure various aspect of instruments.

Tammy


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Bowmoreman
Clear enough skies
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Reged: 09/11/06

Loc: Bolton, MA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #4998782 - 01/03/12 07:12 AM

Quote:

Questions:
1. Should a GPC be used with the BARCON?
2. Do you recommend 8 Ethos for binoviewing?

I've attached the eyepiece and barlow configuration chart for the TEC140.

I am guessing that the magnification for the configuration is:

2.2x? Barcon--AP16T--T2P--QC--MkV--EP.

To calculate this configuration, I used Tammy's measured magnifications for the 2.7x BARCON/1.25xGPC and 3.09x BARCON/1.7xGPC, and divided their respective 1.19x and 1.42x correction factors and got 2.70/1.19 = 2.27 and 3.09/1.42 = 2.18. Since the BARCON placement are all similar, I just averaged the 2 configurations and came up with 2.2x with a 4% margin of error. If so, that's good enough for me.

BTW, for starters, I just ordered a XW3.5, XW5, 13E, and 24 Panoptic pair for binoviewing last night - just before the price increase. I'll try everything then decide whether I'll go with 8, 9, or 10 EPs for binoviewing once the scope arrives in late Spring. Heck, I want to be certain that I am going to like binoviewing in the first place.

I don't have anything yet, but once I get the scope, EPs, mount, diagonal, MarkV, etc., I'll try Tammy's magnification experiment with a tape measure on the wall to see if the above guestimate is correct on the above configuration.
In evaluating all the info furnished by Tammy, it seems that the ratios of exit pupil diameter and barlow magnification for various configurations are directly proportional. In other words 1.19x barlow will reduce the exit pupil diameter of the EP (without barlow) by 1.19x. I am going to try to see if I can calculate the magnification ratios in a different fashion for all the cases by measuring the exit pupil diameters for each case on the TEC140 using an accurate vernier calipers. Here it is:

epd - calculated exit pupil diameter of E.P.
epdb - meausured exit pupil diameter with barlow
barlow mag - barlow mag. factor for particular configuration.

mag = 980/EP.F.L.
epd = 140/mag

Barlow mag = epd (no barlow)/epdb (measured with barlow)

Once again, thank you Tammy and Mark for the great discussion and shared knowledge!
HAPPY NEW YEAR,
George




Well, George... I think you will like it a lot...

I just gad my first BV session with my new Tak TOA130 last night, with my Denk IIs super system... And the Pan 24s... It was magical at all three mags, tho seeing was a bit of a factor at highest power.

You are pretty local, if you want to check out the experience sometime, just drop me a PM...


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Bowmoreman]
      #5000064 - 01/03/12 10:01 PM

Tammy wrote:
Quote:

"I took many shots like above with macro lens and counted pixels in Photoshop to get good accuracy. When you use Barlow lens, exit pupil becomes too small to get good measurement.
It is also becoming cumbersome when you are to measure more than 70 eyepieces, a dozen of Barlow lens, extension tubes, diagonals, 3 different binoviewers etc
I think I spent hundreds of hours(cloudy night/day time of course) over several years to measure various aspect of instruments."




Nice photo, Tammy. I think I'd use the exit pupil technique only on low magnification EPs since I'd only be calculating for the barlow magnification factor.

Bowmoreman wrote:
Quote:

"Well, George... I think you will like it a lot...
I just gad my first BV session with my new Tak TOA130 last night, with my Denk IIs super system... And the Pan 24s... It was magical at all three mags, tho seeing was a bit of a factor at highest power.
You are pretty local, if you want to check out the experience sometime, just drop me a PM..."


Thanks, Dave! Great to hear from you Dave. PM sent.

George


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #5013018 - 01/11/12 10:26 PM

Another setback:

It's official, Astro-Physics has no plans of offering the Baader Mark V binoviewer with a T-2 prism diagonal. First they said that the T-2 prism diagonal might arrive in April, 2012. Today I heard that there are no plans of ever offering the Baader T-2 prism diagonal. Why do manufacturers have to tamper with success? They state on their site:

"Mirror Diagonal - The Baader T2 Mirror Diagonal features durable, 99% reflective Maxbright dielectric coatings. Its compact size allows the shortest possible light path. It is also part of the T2 system, allowing a variety of configurations. The mirror diagonal offers the same optical performance as the prism diagonal that was offered prior to December 2011."

Unrelated baloney! They fail to mention that you would need even a longer focus distance than ever before with a mirror vs prism diagonal! It's bad enough that you need extra extenders, now you'll need even more distance. I am so sick of manufacturers tampering with success - first TEC with its focuser, now AP short changing a proven Zeiss design and charging the same!

All the Glasspath correctors were designed and specifically matched for use with the T-2 prism diagonal. They're not redesigning those GPCs for a mirror diagonal. This is not good news any way you cut it. I don't buy the excuse that you can't see the difference in optical quality. Yea if you limit yourself on a f/7+ scope. What if you wanted to use it on a f/4 scope? Besides, anyone spending $2200+ on a binoviewer system (MkV, Barcon, GPCs) - there should be absolutely no compromise parts and no losses in versatility!

1. How much longer is the back focus for a mirror vs prism diagonal?...
2. What will happen to all the barlow magnification factors with a mirror diagonal, instead of a T-2 prism?...
3. Is there anyway of buying a new 2" Baader T-2 prism diagonal?...

Edited by 10gauge (01/11/12 10:35 PM)


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Tamiji Homma
Post Laureate
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Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #5013092 - 01/11/12 11:15 PM

Quote:


1. How much longer is the back focus for a mirror vs prism diagonal?...
2. What will happen to all the barlow magnification factors with a mirror diagonal, instead of a T-2 prism?...
3. Is there anyway of buying a new 2" Baader T-2 prism diagonal?...





Hi George,

No more Baader T-2 Prism Diagonal? That's too bad. I hope it is temporary thing.

The Baader T-2 Mirror Diagonal is about 17mm longer lightpath than prism one. It is shorter than 2" mirror diagonal.

Magnification factor comparing to prism? Tad more, maybe 10% or so when you have BARCON in front of diagonal. I can measure it this weekend.

2" Baader/Zeiss Prism diagonal is very hard to find specially new. I am not sure they are making any more.

Here is side-by-side T-2 Prism and 2" Prism Diagonal, nosepiece removed:


Tammy


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #5013137 - 01/11/12 11:49 PM

Hi Tammy, Thank you for the quick response, great information, and photos! Wow, is the T-2 prism diagonal a 1.25" diameter?... Looks much smaller than the 2" Prism Diagonal. I am wondering, if the the T-2 prism diagonal on the Mark V bino is the same as the "T-2 Prism Star Diagonal" as sold at Alpine Astro?

http://www.alpineastro.com/Star_Diagonals/Star_Diagonals.htm

If so, I may swap the Baader Mirror prism (BP1A), and use the T-2 prism diagonal from Alpine Astro. They're showing availability for Feb 2012. I'll cancel my order for the A-P Maxbright 2" mirror diagonal and use the Baader Mirror Diagonal for cyclops mode.

... Tell me about it, I really hope they bring back the T-2 Prism! I told the lady on the phone that if Roland is taking a poll, put my vote in for the T-2 prism over the Mirror diagonal.

George


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Tamiji Homma
Post Laureate
*****

Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #5013156 - 01/12/12 12:12 AM

Hi George,

http://www.alpineastro.com/Star_Diagonals/Star_Diagonals.htm

That is Baader T-2 Prism Star diagonal. It is the same as Astro Physics sells with MarkV. The clear aperture of the diagonal is 34mm. It is larger than 1.25" eyepiece clear aperture.

Tammy


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10gauge
sage


Reged: 10/31/10

Loc: Boston
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #5013187 - 01/12/12 12:42 AM

Thanks, Tammy. Great, then I'll just buy the T-2 Prism Star Diagonal for my peace of mind as soon as it's available. What a godsend you are!

George


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: 10gauge]
      #5013399 - 01/12/12 07:19 AM

Greetings,

A couple o' things.

> first TEC with its focuser,

I wanted to note that after another few weeks of heavy use, I can say that I've detected no unwanted movement of the focuser. Since you posted about it I've been kind of testing it. I do think it's OK.

Also... seems like a very good decision to make sure you get the prism diagonal. I was looking at the Alpine website link above, and I realized that they actually use exactly the same photo for both the prism and the mirror diagonal!! Check out the 2 pics on the left. So I had a look at mine. I'm embarrassed to admit it, but actually I'm not completely sure it's the prism diagonal and not the mirror diagonal. It looks similar to Tammy's pic above, but as I've never inspected a mirror diagonal, I don't know for sure, especially since the 2 Alpine photos are the same. After all there is a "mirror" effect going on in both diagonals, as both reproduce the image... and I can't see the prism. So I took a bunch of pictures of my diagonal. Rather than wreck this thread with a bunch of diagonal pics, I posted them here:
http://yepfjgnidfgd.blogspot.com/
I was hoping that anyone (Tammy? ) could glance at them and confirm that it's the prism diagonal? They say there's no such thing as a stupid question so I'll try not to feel too stupid about asking this... anyway I hope the pics might be somewhat interesting to anyone considering buying a diagonal...


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Tamiji Homma
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Reged: 02/24/07

Loc: California, USA
Re: Denk II Super System or Baader Mark V For TEC140? new [Re: mark8888]
      #5013765 - 01/12/12 11:40 AM

Hi Michael,

I think you have a Baader T-2 Prism Star Diagonal. With prism diagonal, you should see flat glass surface on both ends. With mirror, you won't see glass, it is a mirror 45 degree diagonal inside.

Here is Baader diagonal family photo

From left to right, star prism, mirror, amici prism, star prism, star prism.





Notice you don't see reflection with the second from left, it is mirror not visible from this angle, inside diagonal housing.

Tammy


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mark8888
Carpal Tunnel


Reged: 09/24/10

Re: Denk II Super System or Baader Mark V For TEC140? new [Re: Tamiji Homma]
      #5013837 - 01/12/12 12:29 PM

OK, great, thank you very much Tammy!!!!!
That sure makes it clear, I do have the prism diagonal.

Love your family photo. My family is young but definitely growing. Just received a pair of 13T6 eyepieces today .

I notice in your photo that on the mirror diagonal and only the mirror diagonal, the hole is really off-center. I also noticed that in some google photos I found of it... but not on the Alpine website. That's what confused me.

I also have the amici prism, but haven't used it yet. It sits on the table and I just kind of consider it. I'm afraid I'll get addicted to seeing everything correctly oriented and use it all the time...

Thanks again!!!!!!!!!!!!!


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