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Hooked on small scopes

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#276 oldtimer

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Posted 11 October 2018 - 10:25 AM

Just picked up a Meade 70mm F10 model 70 AZ AR from Ebay. This is the somewhat older silver tube version of the Meade 70mm F10 'Infinity ' model being sold today. This is my second one and I'm glad I found it as I should have never given up the first one. At F10 with a tube length of only 29.5" it exceeds the Sidgwick standard and exhibits virtually no CA. It has a nice 5" long dew shield and comes with, 90 degree 1.25" diagonal, 2 1.25"  Meade MA eyepieces (25 and 9mm) and red dot finder. Total cost with free shipping $45.

 

Of course it is Alt-AZ mounted so right out of the box the mount was discarded and the associated tube attachments were removed.  The collimation was a bit off but after removing the one screw that held the cell in place I was able to adjust the collimation and super glue it in place. I now have it mounted up with rings to a beefed up EQ mount with an RA drive. First tlight I viewed Saturn at 140X with a better diagonal and a quality Plossl. and got a perfect sharp image. 

 

Bottom line' Why would any one spend a fortune on a 70mm APO???? 


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#277 rerun

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Posted 11 October 2018 - 11:21 AM

I made my Takahashi FOA60 ready for vacation. It will be the first time I use it out of my backyard. The sky is a bit darker there and I hope for good clear nights.

The smaller case for the scope is new to save same space . It includes the eyepieces Hyperion Zoom 8-24mm , Nagler 11mm , Baader  Morpheus 4,5mm and a Baader Zenithprism 1 1/4 " .A red light lamp and a pencil with sharpener fits in the case too. The case is very small with 47x27x16cm . 

This is my vacation grab and go equipment.

 

Clear skies Markus 

 


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#278 Bomber Bob

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Posted 11 October 2018 - 11:44 AM

Why would any one spend a fortune on a 70mm APO????

 

- Views that are virtually free of false color.

 

- DSO imaging.



#279 Erik Bakker

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Posted 11 October 2018 - 11:46 AM

Very compact travel gear Markus!

 

Hope mount and head do OK for you and are not too small in use under the stars. Especially the head you've chosen.

I've had that a few times, so now tend to pack an extra kilo and a few more centimeters of tripod and head to combine my travels with an enjoyable mount. But sometimes I had to compromise and took a lighter and smaller tripod and head. But luckily, those darker skies will make up for any inconvenience waytogo.gif  


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#280 rerun

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Posted 11 October 2018 - 12:26 PM

Thank you Erik,

 

It is very compact now.

The Videohead works well. Even observing M57 in zenith is possible without problems. I have to save kilos and space more would not fit in my car with the suitcases we need too for our trip

I will see  how the scope will perform under darker sky. 

 

Clear skies Markus 


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#281 Erik Bakker

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Posted 11 October 2018 - 12:32 PM

That's good news about the stability at zenith Markus.

 

Enjoy your vacation and those dark skies!


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#282 bbqediguana

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Posted 11 October 2018 - 06:30 PM

Why would any one spend a fortune on a 70mm APO????

 

- Views that are virtually free of false color.

 

- DSO imaging.

Very true, but I get the spirit of what oldtimer is saying. I also have a 70mm f/10 and it cost me $40. The optics are it are great, CA isn't overly intrusive until you get into "ludicrous" power for this scope (about 120x - 140x). So for $40-$50 we got 75-85% of the performance of a 70mm APO for 10% of the price. That's a pretty good deal.

 

Having said that, would I like a 70mm APO? Absolutely! But would I go out and buy one right now given how well my 70mm achro does? No way! My next APO is going to be a 102 (I already had one previously and proving that my judgement is seriously flawed, I sold it).

 

All of this assumes visual only. I have no idea if these inexpensive achromats would be any good for DSO imaging. Oh, and did I mention that my judgement is flawed? :)


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#283 barbie

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Posted 11 October 2018 - 10:43 PM

Same here. I had considered getting a 70mm apo but the 70mm F10 achro is so well color corrected that it would be pointless to do so.  Besides, with the 70mm F10 it's much easier to attain higher magnifications with simpler eyepieces of longer focal length than with a short focus apo, which I've had in the past and only found useful for widefield DSO work and digiscoping for nature photography.  I hate using a 3mm eyepiece to only get 120x and much prefer using a barlowed 9.7mm eyepiece to attain the highest possible magnification in the 70mm f10 instrument.  As I previously stated, I can use a simpler eyepiece design and not have to worry about other aberrations such as field curvature in the image without having to invest in more complicated, expensive eyepieces.YMMV.


Edited by barbie, 11 October 2018 - 10:45 PM.

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#284 contrailmaker

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Posted 11 October 2018 - 10:58 PM

Of course slow achros can be excellent telescopes too. And evidently the prices are hard to beat. The advantages of faster scopes are their size and their wide FOB capability.  Unfortunately the shorter the focal length, the more complicated (read more expensive) the optics have to be in order to be well corrected.  Well worth the price if you need something that fits in a backpack.

 

CM


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#285 Astrojensen

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Posted 12 October 2018 - 09:56 AM

Same here. I had considered getting a 70mm apo but the 70mm F10 achro is so well color corrected that it would be pointless to do so. 

That, I'm afraid, depends on the eyes that are looking. Some people see chromatic aberration MUCH more readily than others do. Age can play a significant role in this, as older eyes usually see blue much less intense, or at all. One's eyes can also get accustomed to it and uncounsciously filter it out to a rather amazingly large degree. When I have used my 80mm f/15 Vixen achromat for a while, I am hardly aware of any false color at all, but if I set up my 85mm f/19 Zeiss apo or my newtonian next to it and observe with them for a few moments, it becomes immediately obvious that the 80mm achromat does indeed have false color.

 

Thus, what to you might appear as a 70mm f/10 "apo" might to others be nothing more than a decently corrected achromat and certainly not an apo.  

 

 

Clear skies!
Thomas, Denmark


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#286 barbie

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Posted 12 October 2018 - 10:23 AM

First of all, I never said it was an apo.  I DID say it was a well corrected achromat.  Read my post again!!



#287 Sarkikos

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Posted 12 October 2018 - 11:04 AM

The worst thing about long refractors is not the CA, it's the length of the OTA.  

 

Mike


Edited by Sarkikos, 12 October 2018 - 11:04 AM.


#288 bbqediguana

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Posted 12 October 2018 - 11:18 AM

The worst thing about long refractors is not the CA, it's the length of the OTA.

Mike


Very true! That is why I like this 70mm f/10 scope - it is less than 30” in total length including the diagonal.

Edited by bbqediguana, 12 October 2018 - 11:21 AM.


#289 Bomber Bob

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Posted 12 October 2018 - 11:54 AM

The worst thing about long refractors is not the CA, it's the length of the OTA.

 

I hope you don't mean this:

 

Edmund 4 F15 - OTA Complete S99.jpg

 

It's my Favorite of the Collection.


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#290 Astrojensen

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Posted 12 October 2018 - 12:40 PM

First of all, I never said it was an apo.  I DID say it was a well corrected achromat.  Read my post again!!

You didn't say it was an apo, but you said it was so well color corrected, that it was pointless to buy an apo. I just wanted to say that it depends on who you ask. To my eyes, for example, a 70mm f/10 achromat has quite noticeable false color on bright objects like the Moon and the Sun and an apochromat is a visible step up in image quality. 

 

 

Clear skies!
Thomas, Denmark


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#291 desertlens

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Posted 12 October 2018 - 12:44 PM

Bomber Bob, "Dancing with the Stars" or "Born to be Wild"? How's the vibration level on that beauty?


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#292 Astrojensen

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Posted 12 October 2018 - 12:58 PM

The worst thing about long refractors is not the CA, it's the length of the OTA.  

 

Mike

I think it's a bit of an aquired taste. In my experience, the long OTAs also has some advantages. Easy to focus due to the immense depth of focus. Easy to use with binoviewers (if properly designed). Steady images, because the objective is far above the ground and away from the observer's body heat. The advantages quikly add up. I have experience with both short and long focus apochromats (and achromats, but we're talking apos here) and I far prefer the long focus ones, when it comes to lunar/planetary/solar/high magnification observing. But that's just me, of course.   

 

gallery_55742_4772_565770.jpg

 

They sure are bigger and need a much beefier mount, though, so they're not for everyone. Still, I think it's a shame not more has had the opportunity to try one out, because I suspect that a lot of people would very much like the viewing experience, if they had the chance to try one. 

 

 

Clear skies!

Thomas, Denmark


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#293 Bomber Bob

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Posted 12 October 2018 - 01:29 PM

Bomber Bob, "Dancing with the Stars" or "Born to be Wild"? How's the vibration level on that beauty?

I'm an old Hippy, so for me it's the 5th Dimension singing the Aquarius Medley from Hair...


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#294 Mr Onions

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Posted 12 October 2018 - 01:33 PM

Howay The Bruins!

Skylight carton lens 60/1000

This can do some damage on the moon and Jupiter too.

The 10.5mm plossl gives a wonderful 95X which is just right for me.

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  • Skylight.jpg

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#295 Sarkikos

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Posted 12 October 2018 - 02:00 PM

I think it's a bit of an aquired taste. In my experience, the long OTAs also has some advantages. Easy to focus due to the immense depth of focus. Easy to use with binoviewers (if properly designed). Steady images, because the objective is far above the ground and away from the observer's body heat. The advantages quikly add up. I have experience with both short and long focus apochromats (and achromats, but we're talking apos here) and I far prefer the long focus ones, when it comes to lunar/planetary/solar/high magnification observing. But that's just me, of course.   

 

gallery_55742_4772_565770.jpg

 

They sure are bigger and need a much beefier mount, though, so they're not for everyone. Still, I think it's a shame not more has had the opportunity to try one out, because I suspect that a lot of people would very much like the viewing experience, if they had the chance to try one. 

 

 

Clear skies!

Thomas, Denmark

All that scope needs is an extension on the front for a dew/light shield.  Make it longer!

 

:grin:

Mike


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#296 barbie

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Posted 12 October 2018 - 03:22 PM

You didn't say it was an apo, but you said it was so well color corrected, that it was pointless to buy an apo. I just wanted to say that it depends on who you ask. To my eyes, for example, a 70mm f/10 achromat has quite noticeable false color on bright objects like the Moon and the Sun and an apochromat is a visible step up in image quality. 

 

 

Clear skies!
Thomas, Denmark

Well to my eyes, my 70mm F10 achro has very little color, even on the moon and is very well corrected. I've also had fast apos and never cared for them.  The fast apo, on the other hand, will have residual aberrations and still need complicated, more expensive eyepieces to help in correcting those aberrations so for my taste, I'll pick the longer achromat anyday over a fast apo.  So yeah, it's pointless for me to buy a 70mm apo.lol.gif

Also, you may want to read AGAIN my post from yesterday(#283) regarding simpler eyepieces, etc.grin.gif


Edited by barbie, 12 October 2018 - 03:46 PM.


#297 contrailmaker

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Posted 12 October 2018 - 08:11 PM

Well to my eyes, my 70mm F10 achro has very little color, even on the moon and is very well corrected. I've also had fast apos and never cared for them.  The fast apo, on the other hand, will have residual aberrations and still need complicated, more expensive eyepieces to help in correcting those aberrations so for my taste, I'll pick the longer achromat anyday over a fast apo.  So yeah, it's pointless for me to buy a 70mm apo.lol.gif

Also, you may want to read AGAIN my post from yesterday(#283) regarding simpler eyepieces, etc.grin.gif

This falls in the personal preference category. I have owned many achros over the years yet, once I got my first apo that was it. The difference is obvious to me and worth the extra cost. Due to physical space and other reasons all my refractors are short focus apos. The eyepiece requirements are not an issue for me. So, no wrong answer here. Get what works for you best.

 

CM


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#298 Tyson M

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Posted 12 October 2018 - 11:31 PM

I think it's a bit of an acquired taste. In my experience, the long OTAs also has some advantages. Easy to focus due to the immense depth of focus. Easy to use with binoviewers (if properly designed). Steady images, because the objective is far above the ground and away from the observer's body heat. The advantages quickly add up. I have experience with both short and long focus apochromats (and achromats, but we're talking apos here) and I far prefer the long focus ones, when it comes to lunar/planetary/solar/high magnification observing. But that's just me, of course.   

 

Thomas, Denmark

Not just you, me as well. I did try plenty of short compact refractors, which I liked. If grab and go is the ultimate priority then they are your tool to observe with. Afterall, I have a 6" short focus achro because it is large and portable and I love it.

 

If I have a choice and space is not extraordinary limited, I will always prefer a longer frac in smaller sizes. My 80 F7.5 refractor is borderline for what I consider long, and my 102mm F8.8 refractor would be as well. 


Edited by Tyson M, 12 October 2018 - 11:57 PM.


#299 Steve Allison

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Posted 12 October 2018 - 11:47 PM

Short focus Apos look funny. Sure, less space- but less beauty, less grace!



#300 Astrojensen

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Posted 13 October 2018 - 01:43 AM

Well to my eyes, my 70mm F10 achro has very little color, even on the moon and is very well corrected. I've also had fast apos and never cared for them.  The fast apo, on the other hand, will have residual aberrations and still need complicated, more expensive eyepieces to help in correcting those aberrations so for my taste, I'll pick the longer achromat anyday over a fast apo.  So yeah, it's pointless for me to buy a 70mm apo.lol.gif

Also, you may want to read AGAIN my post from yesterday(#283) regarding simpler eyepieces, etc.grin.gif

I do fully agree with everything you say about simpler eyepieces, etc. All I wanted to say was that color correction is a very subjective thing. 

 

And I also agree about *fast* apochromats, but an apochromat doesn't NEED to be f/6, though they're nearly always made this fast today, which is a darn shame. I'm all for the f/10 - f/15 apo. My 85mm Zeiss is f/19. 

 

 

Clear skies!

Thomas, Denmark


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