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Economical refractor

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#1 ppfilbert

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Posted 08 January 2013 - 10:06 PM

Well My OLD C8 is close to dead. images through it are awful even after collimnation. Im buying a 300MM APO camera lens for piggyback but i want a New Refractor. Sadly i know very little about refractors, all i have ever had is an SCT, but many imagers tell me i NEED a refractor. thing is there are SOOO many types models Doublets, triplets ACHRO APO ED ect, jeesh.

So heres where im at i might be able to swing 1000$, but likely 700$ or so, prefer less honestly. im imaging with my camera so clarity is needed. i only need an OTA, i have a good CG5-gt. so As CN has always been good on advice , i REALLY could use some advice and Intel on what i might think of buying. an ES 102 Achro is 399$ but is it worth it, or good enough. or do i need to step up to a 899# triplet APO.

Thanks in advanc efor any intel or help.

#2 dlpville

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Posted 08 January 2013 - 10:45 PM

The issue with using an achro is that chromatic aberration rears it's ugly head as a noticeable difference in image size depending on wavelength; this is what causes the color fringing in achros. The objective size of an apo isn't a deal killer, because you can shoot more exposures and stack them.
Best advice I've seen is go ahead and find an apo that fits your budget, even used ones will give you results that you'll be proud to display.

#3 ppfilbert

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Posted 09 January 2013 - 11:16 AM

ok looking about i find the Sky-watcher pro 100MM apo for 749$. perfect in my range. But how would it be Unguided on a CG5-gt?this is a HUGE amount of Money for me, i pretty much get the chance to spen like this Once a year (income tax) and this will be all my money available. i just dont want to make a mistake

#4 terry59

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Posted 09 January 2013 - 11:25 AM

A good choice would be either the Orion ED80 or the Skywatcher version. FPL-53 glass and a proven AP scope. You'd need a field flattener and the Orion version works well with it. For versatility, the Orion 0.8x reducer works too and gives 480mm at f/6.

#5 rflinn68

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Posted 09 January 2013 - 12:25 PM

I really like my AT65EDQ. It cost $599 brand new and has a built-in field flattener. I think everyone is sold out of them again but I see them a lot used for even less money. It is a 420mm focal length scope at f/6.5 and has the FPL-53 element. Lots of good photos out there that were taken with this scope. It even comes with a dovetail and some really nice mounting rings.

#6 rflinn68

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Posted 09 January 2013 - 12:28 PM

This looks like a really good deal as well!

#7 ppfilbert

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Posted 09 January 2013 - 01:02 PM

It indeed does, sadly im in Prep stage, Funds become available when Income tax come back, bout feb 14. so got a month. you honestly think im better off going Used rather than New, im Just very nervous about buying used unseen even from here, though i have a much better feel here. i know i can prolly get about 1.5 times the scope used, just scares me

#8 ppfilbert

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Posted 09 January 2013 - 02:14 PM

welll another friend telling me I need to Stay with a faster scope. recocmending the ES 80MM ED triplet. Anyone have the scope can share images they have captiured?

#9 watcher

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Posted 09 January 2013 - 04:59 PM

Not into imaging myself, but faster is not necessarily the best. I know that good results depend on your imaging equipment and preferred targets, as well as local sky and light conditions.

I love refractors, but a scope for imaging is another thing. Imagers can tell you better how fast a scope you might like if they know your equipment and other factors, but if you don't really need a short 80 or even 60mm scope, you might be a lot better off with an 6 or 8" Astro-Tech imaging Newt or maybe a 6" Rithey-Chretien. If it's a better match for your criteria, it could save you some bucks. If your heart tells you refractor, regardless of everything else, or if a fast refractor really is the best fit, I would suggest looking for a used TMB 80SS, or better yet, a 92SS with a Feathertouch.

#10 dhaval

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Posted 09 January 2013 - 06:11 PM

If you are truly going to get a refractor, I would say, go get the AT90EDT. It is a solid refractor for imaging with an amazing focuser - will easily hold a ton of load without flinching. I have not imaged with some of the 80mm scopes, other than the ES80ED APO, but can vouch for the image quality of the ES80APO after a focuser upgrade. I would also look very closely at the AT65EDQ given that it comes with a flattener - I am not sure about its focuser though, so an upgrade maybe required.

Things to keep in mind if you are buying a refractor -
1) Buy a well color corrected refractor
2) Ensure you get a decent focuser on the scope - either as part of the scope (TMB92SS, AT90EDT) or upgrade the stock focuser to either a Moonlite or FT
3) For imaging, you don't need a whole lot of aperture, 3in to 4in will do nicely, however, ensure the scope is sufficiently "fast" - F7 or lower, otherwise, you will have to find a reducer for your scope
4) Lastly, you will need a flattener, unless you buy refractors with 4 lens design

As you try and narrow down the field, what you will find is that you will very quickly go over budget. If money is your single limiting criteria, then I would say, go with a large aperture, significantly faster reflector - an AT10in imaging newtonian will be perfect!

Let us know how things work out.

Dhaval

#11 ppfilbert

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Posted 09 January 2013 - 06:35 PM

the AT90EDT is great , but its about 300$ out of my price range. i really need to keep it under 1000$, would prefer under 800, but i can swing it if necessary. as for ad-ons those would all be down the line a few months to lil more. perhaps if i find a Good Qua used one i might pop, but outside of 1K i just cant play :(

#12 dhaval

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Posted 09 January 2013 - 06:59 PM

Post a wanted ad - given that you are still a month or so away from making the actual purchase, you might get lucky! I sold mine a few months ago for $900 and that included the rings and mounting plate.

Dhaval

#13 desertrefugee

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Posted 09 January 2013 - 10:57 PM

I guess I'd ask what's wrong with the C8? I know this is the refractor forum, but a C8 - which you already have - working at C6.3 makes a pretty formidable imaging tool.

Dead seems so...final.

#14 rflinn68

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Posted 10 January 2013 - 11:03 AM

A C8 is definitely not for a beginner in astrophotography. I own an AT8IN f/4 astrograph, an AT65EDQ, and a C8 with f/6.3 focal reducer. Focal length is too long on the C8 for a beginner. AT8IN is too heavy for imaging on a CG5. The AT65EDQ on a CG5 is IMO the best beginner set up one can buy. The focuser on the AT65EDQ is great for a factory focuser. I see no need at all to upgrade. The wife and I are beginners and just bought our autoguider and the frustration level imaging with the AT65EDQ has all but disappeared. This is our first stacked and processed image we ever took. Once we master the 65mm/CG5 combo then we will drag out the AT8IN and CGEM DX again. For some really good pictures to see what this little 65mm is capable of go to Astronomics website and check out some of the images they have posted. This is 80 minutes worth of 4 minute exposures (20X240sec) taken with an unmodified T3 camera at ISO 800.

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#15 rflinn68

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Posted 10 January 2013 - 11:22 AM

Also here are some comparisons between the AT65EDQ and the ES80. The AT65 is $200 cheaper than the ES80. The AT65 has premium FPL-53 optics while the ES80 uses a FPL-51 equivalent. The AT65 is a quadruplet with a built-in field flattener while the ES80 is a triplet and will require a field flattener that will add even more to the price difference. The AT65EDQ also has a very nice focuser that is rotatable, a very nice feature to have on a imaging scope.

#16 terry59

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Posted 10 January 2013 - 11:35 AM

Also here are some comparisons between the AT65EDQ and the ES80. The AT65 is $200 cheaper than the ES80. The AT65 has premium FPL-53 optics while the ES80 uses a FPL-51 equivalent. The AT65 is a quadruplet with a built-in field flattener while the ES80 is a triplet and will require a field flattener that will add even more to the price difference. The AT65EDQ also has a very nice focuser that is rotatable, a very nice feature to have on a imaging scope.


The AT65EDQ also has a high incidence of problems with pinched optics. I seem to remember that you were fortunate and didn't have that problem but many do.

#17 rflinn68

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Posted 10 January 2013 - 11:48 AM

Also here are some comparisons between the AT65EDQ and the ES80. The AT65 is $200 cheaper than the ES80. The AT65 has premium FPL-53 optics while the ES80 uses a FPL-51 equivalent. The AT65 is a quadruplet with a built-in field flattener while the ES80 is a triplet and will require a field flattener that will add even more to the price difference. The AT65EDQ also has a very nice focuser that is rotatable, a very nice feature to have on a imaging scope.


The AT65EDQ also has a high incidence of problems with pinched optics. I seem to remember that you were fortunate and didn't have that problem but many do.


I havent heard of that problem

#18 terry59

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Posted 10 January 2013 - 11:56 AM

Also here are some comparisons between the AT65EDQ and the ES80. The AT65 is $200 cheaper than the ES80. The AT65 has premium FPL-53 optics while the ES80 uses a FPL-51 equivalent. The AT65 is a quadruplet with a built-in field flattener while the ES80 is a triplet and will require a field flattener that will add even more to the price difference. The AT65EDQ also has a very nice focuser that is rotatable, a very nice feature to have on a imaging scope.


The AT65EDQ also has a high incidence of problems with pinched optics. I seem to remember that you were fortunate and didn't have that problem but many do.


I havent heard of that problem


http://www.cloudynig...5001067/page...

#19 rflinn68

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Posted 10 January 2013 - 12:13 PM

Interesting. That seems to be from the batch before these last ones were released and they seem to have that lined out now. Some really good reviews in those links as well. I havent heard a single bad thing about the newest ones that were just released and they've already sold them all. I'm sure Astronomics took care of all their customers problems. They've always took care of me when I've had an issue with some equipment.

#20 Astronomics

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Posted 10 January 2013 - 12:39 PM

There has not been a high incidence with pinched optics. There was around 10 out of 1000 that have had the problem. The pinching came from the retaining ring on the flattener being overly tight. The issue is the "problem" can only be discovered under temperature changes. In house where the temp is above 68 degrees everything is fine. Only as the temperature drops and the temp is cold will the pinching occur. By simply loosening the retaining ring around the flattener to finger tight the issue goes away. So the problem is really a non issue that is impossible to find unless the circumstance align themselves just right.

#21 jrbarnett

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Posted 10 January 2013 - 01:29 PM

What about an Astro-Tech AT72ED ($379) with one of these ($119):

https://www.astronom...ractors_p200...

Regards,

Jim

#22 SteveG

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Posted 10 January 2013 - 01:51 PM

That's a great Pleiades pic, BTW!

#23 rflinn68

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Posted 10 January 2013 - 02:09 PM

Thanks SteveG.....Jim, I also considered that scope before purchasing the AT65EDQ. By the time I bought mounting rings and a dovetail (that comes with the AT65EDQ) I'd have just as much money in the scope. Might as well get the scope with the better optics. For imaging the 7mm difference doesnt matter and overall the AT65 is the better buy. The 72ED does come with a case but I made one for my 65 using the nice factory foam that comes with the scope.

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#24 ppfilbert

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Posted 10 January 2013 - 04:51 PM

ok the AT65EDQ looks amazing, and at 420MM F6.5 wide field woukld be amazing. what limitations would i have , obviously it wouldnt be a good planetary scope, but what kind of deep sky imaging could be done? like M81? or is that not possible? trying to see where i would have range of, i love wide field, and if necessary i might be able to have the C8 rebuilt.
the reason i say its dead is a few things. 1 ) screws have fallen out of the internal and im not the trye to take it apart (until i have a backup) also the internal mirror has issues think its warped, als scratches, the focuser is not workign right. also its an original modle C8 off a nexstar 8 (not Se nothing, just nexstar8) so its 11 years old and has had serious abuse before i even got it, i have tried to do it right but its hits its life.

thanks for all the input thus far. lastly is there Much a difference in resolving power with the Es80Trip and the AT65EDQ im just nervous about steppping down to much. its already a huge step down form the Bazooka i have to a 80MM.

#25 rflinn68

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Posted 10 January 2013 - 05:27 PM

You could probably image M81 AND M82 in the same field. I'm gonna try it when they come back around. Click here to check out a few pictures. You can also search the web for more. There are tons of astrophotos out there that were taken with this scope.






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