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Baader Mark V diagonal

Started by MAURITS , Mar 12 2013 09:41 AM
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30 replies to this topic

#1 MAURITS

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Posted 12 March 2013 - 09:41 AM

I saw on the Baader website that there are 3 different diagonals for the Mark V. :confused:


* T2 MaxBright diagonal mirror - dual T2 connection - 99% reflectivity (2456100 #1A) 35mm free aperture


* Zeiss Jena 90° diagonal prism - 2x T2 connection (2456095 #1B) 35mm free aperture


* Baader 90° Amici Prism - 2x T2 connection (2456130 #2) (most expensive) 31mm of free aperture


What is than the best diagonal for refractor use in combination with the Mark V?

Do I need all the 3 different Glass path correctors (1.25x, 1.7x, 2.6x)?

Thanks! :waytogo:

#2 Mark9473

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Posted 12 March 2013 - 10:19 AM

What back focus do you have on your telescope, Maurits, and do you also want to view at low power without a GPC? If you don't mind using a GPC then the optical length of the prism won't matter much.

#3 MAURITS

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Posted 12 March 2013 - 11:30 AM

Mark, the back focus of the TOA 150B is 214 mm.
Than, do I need all the 3 GPC's?

#4 Eddgie

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Posted 12 March 2013 - 11:56 AM

There is one more choice... This is the Baader standard Prism T2-01C

This prism has a clear aperure of 32mm, but that is larger than needed for even the biggest 1.25" eyepieces,

It has a light path that I think is only 38mm.

I own one and the performance seems to be quite excellent even though it does not have a Zeiss prism. Easily the best prism diagonal I have ever owned.

If you use this with a Baader Mark V, the total amount of back focus required should only be about 160mm or 170mm meaning you should be able to reach focus without a GPC.

Depending on the scope, you might like to have a high powered GPC for planets, but my take on that is that it may be easier just to use a Barcon rather than swap out GPCs in the field.

But with over 200mm of back focus, you can get away with pretty much any of the diagnals you listed and still reach focus without a GPC.

#5 MAURITS

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Posted 12 March 2013 - 01:27 PM

Thanks Mark!
Eddgie thanks for the great input!

#6 tomcody

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Posted 12 March 2013 - 01:30 PM

I would recommend either the 1A (mirror) or 1B (prism) for best visual results.
The difference is that the mirror is brighter but may show some light scatter around planets & bright objects, the prism will not show that scatter (the planets seem to float in a darker background) but is not as bright an image. With 4" & 5" scopes, I prefer the mirror, with your 6" it probably doesn't matter.
As for the GPC's Astro-Physics recommends using one to narrow the light path and sharpen the view unless you are using a barlow (which does the same thing), so I suggest you get the 1.25 GPC just for the quality of view as you will not need it to reach focus with the TOA150.
One more thing, be sure to use a 2" nose piece for a secure connection to the scope (the 1.25" noses pieces are hard to clamp tight enough with all that weight on them).
Rex

#7 MAURITS

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Posted 12 March 2013 - 01:46 PM

Thanks Rex for the explanation!

#8 MAURITS

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Posted 13 March 2013 - 02:00 AM

Suppose I use the Mark V with the pan 24mm EP's, and I still make use of the 3 GPC's, do I have than more power on the EP's with for example the 2.6 GPC than without it, or do have I something els.....? :o

#9 Mark9473

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Posted 13 March 2013 - 03:05 AM

You can consider the 2.6x GPC as a 2.6x barlow. Note that the 1.7x GPC has been found to be more like a 1.45x. For the exact magnification you could do drift timing with and without the GPC in place.

#10 Eddgie

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Posted 13 March 2013 - 08:30 AM

As Mark said, the GPC works the way a Barlow does so when it is in place, it will give you about 2.5X more power.

So in essence, this will make your 24mm eyepeices into 9.6mm eyepeices.

The problems with this is that well, it will make your 24mm eyepeices into 9.6mm eyepeices.

What happens though if want 24mm eyepeices? Well, now you have to remove the GPC. The GPC is a little lens in a thin housing that fits between the binoviwer and the diagonal.

If you now want to convert, you have to remove the binoviwer from the diagonal, and remove the GPC, then put it back together. And now you have a very small, delicate lens to tend to in the dark.

Hey, not saying that you can't do it.

But a Barcon is easier.

Also this.... The only time a GPC is beneficial (if it is not needed to reach focus) is when you are using very short focal lenght eyepeices. Once you need magnification greater than you can get with maybe 10mm eyepeices, even very small mis-alignments in the prisms of the bino can cause people to have trouble merging the image.

In many cases though, the alignment of binos is good enought that this isn't a problem until even shorter focal lenghts.

Point is, If you have carefully measured back focus and are sure you don't need a GPC to reach focus I would advise that you simply don't get one until after you have tried them without the GPC.

Changing eyepeices is quicker and easier than changing a GPC, and changing a barlow is quicker than changing a Barcon if you are screwing it into the nose of the bino or diagonal.

Are you buying everything ala carte? I thought when you bought the AP setup it included one or more GPCs.

#11 MAURITS

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Posted 13 March 2013 - 11:46 AM

Thanks again Mark, Eddgie!

I make a good choice for the best diagonal!
Here in Europe is it the Mark V without the 1.25x GPC, only the bino body with fast coupler and 360° rotation and the T-2 quick changer! :(

#12 Eddgie

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Posted 13 March 2013 - 12:45 PM

Then I would wait before you spend more money on it. Try it. See if you like it.

And if you don't need a GPC to reach focus, and you can reach planetry powers using 10mm or longer focal lenght eyepieces, then maybe you won't need a GPC or a Barcon.

But I think if the primary reason you need magnification is for planets so that merging is not an issue, it might be better to just get a Barcon.

The reason I belive the Barcon is a better choice is that the GPC is a very specialized, single use optical component.

The Barcon can be used for any application where a Barlow can be used and maintains a more constant magnification factor based on where it is placed compared to barlow lenses.

It's compliacated though, so do your homework.

#13 MAURITS

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Posted 14 March 2013 - 04:33 AM

Can I do something with the Baader Maxbright 2" diagonal (BA2406210) in combination with the bino Baader Mark V?

Are there disadvantages on a 2" diagonal in combination with the Mark V?


#14 Hesiod

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Posted 14 March 2013 - 06:18 AM

Are there disadvantages on a 2" diagonal in combination with the Mark V

as long as it works, no. But IMHO there are no advantages over the 1.25" Zeiss (or mirror).
Besides, I own both the "standard" prism and the Zeiss, and the latter is only *very* slightly brighter than the first.

As for the GPCs,I currently use a couple of them (1,7 and 2,6) instead of changing the EPs, altough I use the binos whit 1,25" nose, so it is safer switching between them in the dark (in fact I change the whole nose).

But as Eddgie has pointed out, these items are not versatile and if the TOA has not enough BF to use the bino without any of them and with the extra cm the nose cost you, then my advise may not be practical

#15 tomcody

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Posted 14 March 2013 - 09:06 AM

Maurtis,
The 2" diagonal should work fine as long as your scope has enough infocus. There are only two disadvantages in using it
1. if you want to use the binos on scopes with less available infocus. The T2 diagonals are better for that.
2. If that is your only diagonal, I like to remove the binos and insert a diagonal to quickly switch from mono to bino ( taking the diagonal apart and re-configuring it would not make me happy , I like having dedicated diagonals for each purpose).
Rex

#16 MAURITS

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Posted 15 March 2013 - 11:29 AM

Thanks all for the great reply! :D

#17 MAURITS

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Posted 16 March 2013 - 09:09 AM

What can I do with this: BA2456305

Baader 2" glass path corrector 1.8x for refractors etc.
180,00 EUR

Is there a difference between this above and the 3 "stand alone" GPC's (85€ each individual)? :confused:

Just out of curiosity: I have the Takahashi Extender ED 1.5x, can I use it with the mark V instead of the Baader 2" glass path corrector 1.8x for refractors? :confused:

#18 Mark9473

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Posted 16 March 2013 - 10:49 AM

Definitely try the Takahashi first, since you already have it. Baader says that "The binoviewer's long glass path causes colour fringes a normal Barlow lens cannot correct for." but in practice I find that my AP Barcon gives a very high quality image.

#19 MAURITS

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Posted 17 March 2013 - 08:34 AM

What do you prefer for the MARK V: a pair "panoptic" 24mm or a pair "ethos" 13mm or both or something els? ;)

#20 johnnyha

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Posted 17 March 2013 - 12:41 PM

Pan 24s. 13 Ethoi are very heavy, expensive, create an extremely long moment arm, and many people have reported regretting the purchase (oops!! my binoviewer just flipped over from the weight and the eyepieces fell out on the concrete!!). But hey, whatever floats yer boat! :grin:

Good luck! Don't be afraid to try quality orthos, they are magic in a good binoviewer and I HIGHLY recommend them. The ergonomics and ease of use are bloody fantastic. The FOV seems much wider than in mono mode.

#21 MAURITS

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Posted 17 March 2013 - 02:45 PM

Thanks Johnny for your answer!

#22 Aquarist

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Posted 17 March 2013 - 06:41 PM

Pan 24s.


I definitely agree!

Good luck! Don't be afraid to try quality orthos, they are magic in a good binoviewer and I HIGHLY recommend them. The ergonomics and ease of use are bloody fantastic. The FOV seems much wider than in mono mode.


Any specific ones you would recommend?

#23 johnnyha

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Posted 17 March 2013 - 06:52 PM

I would recommend the ZAO-IIs of course. But more realistically :grin:, I have had excellent results with Brandons, UO Orthos aka KK Circle T Orthos, and TV Plossls. There have been numerous threads on the subject just search for "planetary" in Binoviewers or Eyepieces forums. Agena Astro is supposed to have the Kasai HC Orthos in soon which are the same as the old UO HD's aka Baader Genuine Ortho's.

#24 MAURITS

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Posted 25 March 2013 - 06:19 AM

Why sell AP now along with the Mark V setup, the Baader T2 MaxBright diagonal mirror #1A in place of the earlier Zeiss Jena diagonal prisma #1B (was offered prior to December 2011)? Marketing or something else?

#25 tomcody

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Posted 25 March 2013 - 09:23 AM

Why sell AP now along with the Mark V setup, the Baader T2 MaxBright diagonal mirror #1A in place of the earlier Zeiss Jena diagonal prisma #1B (was offered prior to December 2011)? Marketing or something else?

This question has been discussed many times on many forums! There is no definitive answer, I have two possible reasons that I will offer up:
1. As Roland's eyes get older (like mine) he , like me, might now prefer the slightly brighter view of the mirror.
2. Mrs Astro-Physics might have noted that they had an excess stock of mirrors and suggested that before buying any more prisms ( if they are like many companies, they would order once a year and place a big order to get a better volume price), they bundle the mirrors with the binos to reduce stock.
Either answer is as good as the other. You decide, or make up your own reason. :lol:
Rex
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