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Doubt between Meade ACF 8 or 10 inches without ACF

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#1 Eudson

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Posted 24 June 2013 - 10:51 PM

HI, I'm from Brazil and early this forum today, I have a doubt between buying an STC Meade ACF 8 inch or 10 inch without ACF, which is best?

I'm in doubt between:

http://www.bhphotovi..._LX90_ACF_8_...

http://www.bhphotovi..._10_SCHMIDT_...

thank you

#2 Schaden

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Posted 25 June 2013 - 07:57 AM

I was interested in the LX80 but after it came out, I read many think a 10" SCT is undermounted on it. That said, I'd rather have more aperture than ACF optics.

#3 Eddgie

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Posted 25 June 2013 - 08:11 AM

If you enjoy 82 degree and 100 degree AFOV eyepeices, then I think the there may be more benefit in the ACF, but if you are content with 68 degree AFOV eyepeices, I think that more aperture is better and would go for the 10"

For the larger SCTs, seeing often does as much to damage the appearance as the scopes themselves, and when you use the 82/100 degree eyepeices, you get a lot of magnificaiton, which is (to me) the main reason that SCTs have an (undeserved) reputation for soft images. To much magnfication for nights of even moderatly good seeing will show bloated stars. It isn't the design of the scope that does this... It is simply using enough magnification to show the stars with enough angular size to show them as being aberrated.

I would go larger and stick with Panoptic and similar 68 degree eyepeices. You will be rewarded with sharper stars all the time.

#4 Eudson

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Posted 25 June 2013 - 09:30 PM

Thanks for the help, it was very useful, I'm thinking of putting a extra money to buy a 10 inch LX90 ACF, but I like the LX80 mount more than that of the LX90, prefer an equatorial mount, but do not know which one works better.

#5 Starhawk

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Posted 26 June 2013 - 12:23 AM

You need to read up on the LX80.

LX 80 hopes for problem resolution.

#6 *skyguy*

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Posted 26 June 2013 - 01:12 PM

Thanks for the help, it was very useful, I'm thinking of putting a extra money to buy a 10 inch LX90 ACF, but I like the LX80 mount more than that of the LX90, prefer an equatorial mount, but do not know which one works better.


The ACF optics were designed mainly for astrophotography and there is very little to gain when used for visual work over the standard SCT optics. The LX90 is basically a visual mount and not really suited for astrophotography ... you really need to go with the LX200 mount or better. Placing ACF optics on a LX90 mount is pointless ... and don't forget the $400 ... or so ... you'll need to spend for a wedge for deep-sky imaging.

Personally, the 10" non-ACF SCT on the LX-80 mount would make a nice visual setup and the money saved on not needing a wedge could go toward purchasing a small ED refractor for imaging on the LX80 mount.

Good Luck on your selection ... there are many, many possibilities to choose from!

#7 Eudson

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Posted 26 June 2013 - 02:10 PM

I still have no desire in astrophotography, my goal now is great detail on visual observation, mainly deep sky, the ACF optics will give me a wealth of details much more than the standard SCT visual observation? thank you

#8 Eudson

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Posted 26 June 2013 - 02:22 PM

Hi skyguy, thanks for the tip to buy a refractor, which would you recommend me?

#9 Starhawk

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Posted 26 June 2013 - 02:43 PM

Look over on the refractor forum- ask there and include info on how you plan to use it and your approximate budget.

-Rich

#10 Rick Woods

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Posted 26 June 2013 - 02:51 PM

If you enjoy 82 degree and 100 degree AFOV eyepeices, then I think the there may be more benefit in the ACF, but if you are content with 68 degree AFOV eyepeices, I think that more aperture is better and would go for the 10"

For the larger SCTs, seeing often does as much to damage the appearance as the scopes themselves, and when you use the 82/100 degree eyepeices, you get a lot of magnificaiton, which is (to me) the main reason that SCTs have an (undeserved) reputation for soft images. To much magnfication for nights of even moderatly good seeing will show bloated stars. It isn't the design of the scope that does this... It is simply using enough magnification to show the stars with enough angular size to show them as being aberrated.

I would go larger and stick with Panoptic and similar 68 degree eyepeices. You will be rewarded with sharper stars all the time.


I'm not sure that's absolutely necessary. I have a 14" f/10 SCT, non-ACF. I use 82* eyepieces, and have very, very little in the way of edge distortion. Also, I recently acquired an ES100 20mm eyepiece, and the edge correction seems very good in the 14" as well. I'm sure you're correct to a degree; but I think you may be overstating the issue. 82* and 100* eyepieces work extremely well in standard SCTs (at least, in mine).

I do agree that a given eyepiece gives a much higher magnification in an SCT than in a Newt, which contributes to the idea of soft images.

#11 Eudson

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Posted 26 June 2013 - 04:43 PM

I wonder what problems the LX 80 has shown, I noticed several complaints from members of the NC, but did not report what problems, thank you

#12 Eddgie

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Posted 27 June 2013 - 08:28 AM

I think you may be overstating the issue. 82* and 100* eyepieces work extremely well in standard SCTs (at least, in mine).



It is an individual call. I find the level of aberration with a 31mm Nagler in my C14 to be far more than I can tolerate, but I have no visual accommodation.

Even the 22mm Nagler showed to much aberration from the C14 scope to me than a 27mm Panoptic (similar size true field).

So, very individual. I personally am much happeier using 68 degree eyepecies in the C14 and C5.

By comparision, the EdgeHD 8" is flawless using Naglers.Side by side, it is very easy to see the difference in edge performance. In the EdgeHD 8" with the 31mm Nagler, stars are as sharp at the edge of the field as at the center.

As is my 6" APO.

Once you have spent some time with telescopes that deliver truly outstanding edge of field performance (the place were telescopes differ in performance far more than at the center... Central obstruction argument is silly compared to edge of field aberrations of different designs) you become much less tolerant of it.


Ask more people that have moved from a standard SCT to an EdgeHD and I think you may find that I am not alone in this opinion
.

But it is my own opinion, which like yours, is based own each individuals own preferences and tolerances.

You're happy, I'm happy.

We can't know what will make the OP happy though.

I would go with more aperture though. Which eyepeieces he uses to me are far less important that what aperture he settles on. You can easily change eyepeices (if he dislikes Naglers, he can put in Panoptics), but you can't add more aperture to the scope.

#13 Eddgie

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Posted 27 June 2013 - 08:32 AM

the ACF optics will give me a wealth of details much more than the standard SCT visual observation?


No, the ACF optics won't show any more detail than the standard SCT will.

The difference is only to be found at how they behave near the edge of a wide field of view. Stars near the outside of a wide field at low powers will not appear quite as sharp as the center in the standard scope as they will in the ACF.

At the center of the field, the larger aperture will show more detail, but the difference between 8" and 10" is not large. The biggest difference will be that you will get a bit fainter stars in the larger scope, and at the same power, deep sky objects will appear a bit larger.

Otherwise, the ACF optics only make the outside of the field a bit better. Stars will appear as small round spots rather than comatic flares.

#14 Eudson

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Posted 27 June 2013 - 07:49 PM

have a SCT has always been my dream and now I'm about to get, I'm sorry so many questions but do not want to disappoint with the purchase, I am very happy to have been so well received by the staff of CN, thank you all! I use a Meade SCT from a friend who does not know which model to be so old then send a photo for you to identify the model, I can only buy a telescope up to U.S. $ 2,150.00, in your opinion what would be best for me?

http://www.bhphotovi...advancd_vx_8...

http://www.bhphotovi..._10_SCHMIDT_...

http://www.bhphotovi..._LX90_SC_10_...

#15 Eudson

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Posted 27 June 2013 - 10:44 PM

I have no Televue eyepieces are very expensive, everything comes to Brazil with value 3 times more expensive than the value in the U.S., I use the simpler eyepieces ploosl, I know that one day I can have an ethos or nagler TYPE6. The best eyepieces I have is a Meade 16mm SWA Televue 7mm nagler old, and a Meade 32mm plools, I hope to have good results with these eyepieces

#16 Starhawk

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Posted 27 June 2013 - 11:38 PM

The top one of your three is an Edge HD telescope. That's the best OTA you've listed so far. Flat field, good glass. You'll keep it for life. The VX mounts seem to be alright- but you'll keep the OTA when you outgrow it.

-Rich






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