155 EDT vs APQ 150

From several years I am an happy owner of an AP 155 f/9 EDT (1992) that I use mainly for planetary visual observations.
Now I have received an interesting offer to buy a Zeiss APQ 150. I would like to know if, in your opinion, visually I can expect some improvment in performances or if the Zeiss better correction can be only detected in test lab condition.

William Green said:

How could the Zeiss possibly have better correction?

Bill

Better beer? Better wurst?

Zeiss 150APQ is going to be considerably more expensive than the EDT, if you are really interested and can afford it get the APQ but do not sell the EDT until you had a chance to do a side by side comparison, you can always sell the either scopes once you decide.
The last EDT that I recall listed in Amart (#553850) sold for 10K, a pristine APQ will go for 3 to 4 times that amount.
It is my understanding that APQ’s were corrected to be colorless in visual spectrum only, but ultimately you should compare the two.
I have a 1993 EDT, to me this thing is about as color free as a Newtonian.

Vahe

Here is one test of a Zeiss APQ 150/1200. Unfortunately, it was tested at 632.3 nm (red, Helium-Neon laser line)

http://www.soldati.org/soldati.org/APQ_150_1200.html

I suspect there would be no advantage to the APQ, and you'd be giving up 5mm of aperture - admittedly a minor amount - and the cost would likely be substantial.

Another thing to look at is accessories. Can you get a field flattener for the APQ, for instance (if you ever consider photography).

Clear skies, Alan

I have first hand reports of a visual test between a Zeiss APQ 150 and an AP155EDF f7. While incredibly close, the observer comments on the Zeiss having a slightly "whiter" white and a hair better contrast on extreme contrast areas such as brightly lit features at the terminator on the moon and those areas still in darkness. I haven't heard any direct comparisons of the EDT f9 version versus the Zeiss, but I would hazard that the differences would be exceedingly minor and may well be entirely beyond the ability to detect except via interferometric or measured light transmission as a function of wavelength testing.

...now I will be able to answer my own question... I will let you now the result.

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