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Posts Made By: Michael Lalk

January 1, 2008 08:30 AM Forum: Zeiss

Happy New Year 2008!

Posted By Michael Lalk

Dear Astromart members (and of course Zeiss lovers...)!

I wish you all a very Happy New Year 2008 with much health and success.

May the sky be always clear for us!

All the best,
Michael Lalk

December 30, 2008 02:46 PM Forum: Zeiss

Re: zeiss apq production quantities

Posted By Michael Lalk

Hi David,

that is somehow difficult to estimate: there are some APQ's which are newer (after 1995; lenses still from Zeiss) and the APQ from the original production line by Zeiss. My numbers are rough, so please do not stick me to much to them:

APQ 80/500 (only "Funktionsmuster"; functional samples): I know 2 of them
APQ 100/640: around 150
APQ 100/1000: around 250
APQ 130/1000: around 250
APQ 150/1200: around 100

I owned 2x100/640, 2x100/1000 and 2x130/1000. All of them were great. I sticked to an "older" (around 1992) 100/1000 (uncoated lens!).

Best regards and a happy new year!
Michael



August 28, 2002 08:29 AM Forum: Takahashi

Places to buy in UK/Europe?

Posted By Michael Lalk

You can also look at http://www.takahashi.de

There you will find the German main dealer

Michael

October 26, 2002 12:29 PM Forum: Zeiss

Prism Diagonals for APQs

Posted By Michael Lalk

Ben,

Zeiss designed their telescope lenses including a 40mm glass path; somewhat like a tradition. This means for best color correction you will need such a piece of glass. Normaly one will use a prism diagonal. But you can also use a block of glass with the length of 40mm.
In my own observations with an APQ 100/640 I found that it really makes a difference if you use a mirror or a prism (prism diagonal bought from Thomas Baader, Germany).
Around brighter objects you will see color. But also with an AS 100/1000 (which was the main 100mm amateur refractor in former East Germany) you will see that the color correction of this semi apochromatic lens will be much worse when in connection with the prism.

Best Regards,

Michael Lalk
Greifswald, Germany

October 26, 2002 12:34 PM Forum: Zeiss

Prism Diagonals for APQs

Posted By Michael Lalk

..forgot somethig:

"...much worse when *not* in connection with the prism.

Sorry,
Michael

April 28, 2003 10:50 AM Forum: Zeiss

Eyepieces and scopes

Posted By Michael Lalk

Hello Paul,

I have compared the 0.96" and the 1.25" Abbe-Orthos using my Telementor and an APQ100/640
and APQ130/1000 - I must say that the 1.25" version is superior over the older Abbe's.

At first the coatings are much better. I bought my 0.96" Abbe together with the Telementor
in 1984 at the Zeiss store in (East)Berlin. The O-6 had an older MgF2 coating. So the
reflections are much higher than looking at a 1.25" Abbe. Of course - over 10 years of
optical development! But also the glasses are different in the newer Abbe's. Zeiss used some
high index lanthanum glasses and I think the internal light scatter is much lower in these
eyepieces.

The 1.25" Abbe where designed for the new line of APQ refractors. And at these telescopes
they show high quality pictures.

I used a Pentax SMC O-6 and tryed to find differencies to an older O-6 from Zeiss and the
newer A-6. I personaly think that the Pentax and the 1.25" Abbe are closed together. I never
used a binoviewer; perhaps the pictures are different here. But again: both were better
than the older 0.96" O-6.

The name Abbe orthoscopics you gan use for any Orthos around. The design goes back to Ernst
Abbe, one of the founders of Zeiss. In honor to Ernst Abbe Zeiss put the Name "A-#" at the
barrel of the eyepiece.

The prices: I think the eyepieces sometimes are to expensive. I would not pay nearly 800 EUR
for the eyepieces or the barlow. If you can get a Pentax SMC ortho take it! The results are
equal I personaly think.

And the telescopes: I think one must see the effort Zeiss made to develop the ultimate
planet refractor when they designed the APQ. Of course you can have the same color (or
better; why not!!!) correction using high quality glasses like the FPL's and FK like for instance
Roland Christen is doing it with his top refractors (you can check in the glass catalogues
from Ohara and Schott that the optical parameters are very close to CaF2).
I think it is also some kind of beauty to use a telescope which is hand figured to give
the optimun performance for the observer; and Zeiss did it using CaF2 in a triplett.
Then you see how difficult it is to meet the high standarts of Zeiss you can imagine what high
class instrument you hold in your hands if you own an APQ. I would say the "value" is at least
equal to the top line tripletts from Astro-Physics! Again; I would not pay 11.000 USD for an
APQ130 or 7000 for an APQ100. But if you find one for the price the people are asking for their
AP refractors - take it!!! If you find one. I think people are using their APQ's as a kind
of lifetime telescope (so I am doing it).

Hopefully you do not missunderstand me - I started my astronomy "life" with Zeiss instruments.
So perhaps it is also a kind of patriotism...

Best regards from Germany,
Michael


January 24, 2004 01:09 PM Forum: Zeiss

Performance of AS100

Posted By Michael Lalk

Evan,

the AS 100/1000 is a doublet designed by August Sonnefeld at Zeiss during the 30'ies. It is a semiapochromatic objective based on a classic Fraunhofer (doublet with airspaced lenses). It consists of an outer crown and an inner flint element. Both are resistant to the normal air polutions. Until the early 80'ies Zeiss produced uncoated lenses. The newer AS objectives are coated.

It would not be "fair" to compare the AS to an FS objective by Takahashi. The FS is a fluoride doublet with a much better color correction. In fact the construction is very similar to the AS. It is als an airspaced doublet. But I think it is based of the design by Steinheil rather then Fraunhofer.

The AS lenses are extremely well corrected semiapochromates but they can not defeat a well corrected apochromatic objective. If you look for the "absolute" color-free picture it is not the right choice. But if you seek for a piece of fine optical design and finishing (and of course a collectible item) go for it!

Michael

May 16, 2005 11:09 AM Forum: Zeiss

Moderator

Posted By Michael Lalk

Dear Kevin and Walter,

and of course Dear all Zeiss lovers.

I would like to introduce myself a little bit to the forum.

I am 32 years old and work as an assitant professor for Bioorganic and Natural Products Chemistry at the University of Greifswald.

Beside my research on species inside the ocean I love to observe the sky; contrasts attract each other.

I started with astronomy in 1985 when my father traveled with me to the big Zeiss store in Berlin (former East Germany). They had everything one can dream of: AS100/1000's on Ib mounts; Telementors; Telemators and two Meniscas 180/1800. Of course nearly noone in the former GDR could buy such telescopes - but dream of them. And see them in a store; that is no longer possible cwy .

I found a small parcel under my christmas tree that year with the C50/540 objective and two Huygens eyepieces and together my father and me built my first telescope which I still own and use.

Through the years a Telementor, an APQ100/640, an APQ130/1000 and last weekend an ED80/840 "PRESTO" came to me and with these telescopes also my affinity and love to Zeiss telescopes and accessories. And of course I became interessted in the history of development of astronomical equipment at Zeiss. In 1996 I could privatly visit the Zeiss factory in Jena and see how the put together all pieces of astronomical equipment for the amateur; it's a pity...

I hope I can bring my addiction to Zeiss to many astronomers on Astromart and will do my best to be a scout in this forum. If I can help I will do my best.

Herb was so kind to give a second job to me :-) - if you have any German questions please have a look at that forum!

Best,
Michael

June 22, 2005 12:12 PM Forum: Zeiss

Zeiss/Starlight Crayford focuser

Posted By Michael Lalk

Hello Alan,

this looks like an integral part of the Zeiss design - very well made and nice idea, design and finish!

The Zeiss helical focuser is sometimes not the best. Especially at low temperatures it becomes stiff. And the focuser travel is to much for a binoviewer - nobody wants to shorten an original Zeiss tube...

I think this would be a great focuser for my APQ100/640!

Kind regards,
Michael




March 6, 2011 09:56 AM Forum: Astro-Physics

mount upgrades

Posted By Michael Lalk

Tom,

as far as I know: not really.

The gears seem to be different. But perhaps there is a solution I do not know.

Best, Michael