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#1 h00etn

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Posted 29 February 2020 - 02:01 AM

Hello,

 

Newbie here! Well, almost a newbie - planning for what scope to get to start imaging. I am doing my homework and have some experience with visual but want a refractor since I would like to have no to minimal maintenance. I want the carbon since I I read that I will have less focusing issues during the night so I am in for that.

 

I think I am going for the:
Explore Scientific Apochromatic refractor AP 102/714 ED FCD-100 CF Hexafoc OTA

 

but I also know that the wider the FOV the easier it will be so I am also considering the:
Orion Apochromatic refractor AP 80/480 ED Carbon OTA

 

Both are fairly slow, F7 vs F6 but with good guiding that should not be a problem. Both are apochromatic, the ES have the FCD-100 glass while the Orion has the FPL-53 glass.

 

Now, this is the way I am thinking, buying the ES and a 0.7 reducer so that I can get both the wider FOV and when I want a smaller FOV I'll shoot without the reducer.

 

Would you say that it is more difficult to use the 102/714 with a 0.7 reducer than to use the 80/480. Will it be much more difficult to use the 102/714? Any other relevant considerations?

 

Thanks in advance for your knowledge and kind regards,

 

Eric



#2 sg6

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Posted 29 February 2020 - 02:44 AM

Not sure why carbon over a standard aluminium. Half the reason for asking is that carbon hasn't swept aluminium away so I assume that it has little or no advantage. If it were better then it would be more prevelant. Whereas it seems more of a novelty.

 

Main rather odd concern is a flattener for an ES. They seem rare and also a little underwhelming on performance. There are assorted posts asking where to get a flattener for an ES either get one at all or get one one that works. Actually think that ES pulled one of their flatteners+/-reducers as they were so poor.

 

You are going to need a big mount for a 102 f/7 triplet. Especially as there will likely be assorted items added over time - there always are. Get scope weight then look for something that will throw 4x the scope weight around. 4x not 2x as everyone adds stuff, and any stuff has a weight.

 

From limited experience I would go for a Williams Optics scope. For the rather simple reason they seem to have an idea what they are doing in the AP arena. Unfortunately they seem to cost more.

 

An example is I bought one of their adjustable flatteners. All I need to do is get the separation in the right area and then adjust it via the screw thread and lock it. Immensely easy.

 

Will repeat the AP Mantra that "The mount is everything". It is the stable (hopefully) base that everything sits on and it can be the single item that remains over a number of years.


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#3 BQ Octantis

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Posted 29 February 2020 - 02:44 AM

If you're starting out with an f/6-f/7 APO, it means you've already invested heavily in a high-quality equatorial mount designed for AP with a 30-40 lb load capacity…right?

 

I'd personally go for the faster, shorter, lighter Orion, but either would make an excellent DSO scope for an OSC or DSLR camera.

 

BQ



#4 h00etn

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Posted 29 February 2020 - 03:27 AM

If you're starting out with an f/6-f/7 APO, it means you've already invested heavily in a high-quality equatorial mount designed for AP with a 30-40 lb load capacity…right?

 

I'd personally go for the faster, shorter, lighter Orion, but either would make an excellent DSO scope for an OSC or DSLR camera.

 

BQ

Yes, I have the EQ6-R Pro. Supposedly it can take 20 kg. Hoping this will be enough, even with a guidescope, two ZWO's (mini for guiding and ASI294MC Pro for imaging and the ASIAir Pro...



#5 h00etn

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Posted 29 February 2020 - 03:35 AM

Not sure why carbon over a standard aluminium. Half the reason for asking is that carbon hasn't swept aluminium away so I assume that it has little or no advantage. If it were better then it would be more prevelant. Whereas it seems more of a novelty.

 

Main rather odd concern is a flattener for an ES. They seem rare and also a little underwhelming on performance. There are assorted posts asking where to get a flattener for an ES either get one at all or get one one that works. Actually think that ES pulled one of their flatteners+/-reducers as they were so poor.

 

You are going to need a big mount for a 102 f/7 triplet. Especially as there will likely be assorted items added over time - there always are. Get scope weight then look for something that will throw 4x the scope weight around. 4x not 2x as everyone adds stuff, and any stuff has a weight.

 

From limited experience I would go for a Williams Optics scope. For the rather simple reason they seem to have an idea what they are doing in the AP arena. Unfortunately they seem to cost more.

 

An example is I bought one of their adjustable flatteners. All I need to do is get the separation in the right area and then adjust it via the screw thread and lock it. Immensely easy.

 

Will repeat the AP Mantra that "The mount is everything". It is the stable (hopefully) base that everything sits on and it can be the single item that remains over a number of years.

I am not sure, but I have read that the carbon stops the scope from contracting, hence no need for refocusing during the night as it gets cooler outside.

 

Interesting and valuable information about the flattener issue, thank you. I will have to look more indepth on that.

 

Also heard good things about the WO, but the one I find (and that are not +3k) are only doublets....

 

Yes, I am hoping that my EQ6-R Pro will do, even with guding scpe, two cameras (ASI) and the ASIAir Pro.



#6 Kevin Ross

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Posted 29 February 2020 - 03:43 AM

Yes, that mount will do fine. Good choice.


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#7 BQ Octantis

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Posted 29 February 2020 - 03:43 AM

Yes, I have the EQ6-R Pro. Supposedly it can take 20 kg. Hoping this will be enough, even with a guidescope, two ZWO's (mini for guiding and ASI294MC Pro for imaging and the ASIAir Pro...

The EQ6-R Pro seems like an adequate mount for the setup. Just remember that the recommended load limit for AP is half the weight rating.

 

BQ


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#8 WadeH237

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Posted 29 February 2020 - 06:22 AM

I am not sure, but I have read that the carbon stops the scope from contracting, hence no need for refocusing during the night as it gets cooler outside.

Temperature doesn't just affect the tube.  It also affects the optics, but in the opposite way.

 

Have you noticed that none of the high end refractors use carbon fiber?  I have read that manufacturers like Astro-Physics, TEC, etc. use metal tubes because they are more temperature stable than carbon fiber.

 

I believe that one of the engineering reasons to use carbon fiber is for less weight and more rigidity.  That's why you tend to see it used for truss tube poles.


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#9 OhmEye

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Posted 29 February 2020 - 07:31 AM

I am not sure, but I have read that the carbon stops the scope from contracting, hence no need for refocusing during the night as it gets cooler outside.

 

Interesting and valuable information about the flattener issue, thank you. I will have to look more indepth on that.

 

Also heard good things about the WO, but the one I find (and that are not +3k) are only doublets....

 

Yes, I am hoping that my EQ6-R Pro will do, even with guding scpe, two cameras (ASI) and the ASIAir Pro.

CF does not really affect performance in any significant way at this size, other than slightly less weight. Temperature changing focus has as much or more to do with the refraction index of the glass optics changing with temperature than the material the tube is made of.

 

You will want a field flattener regardless of whether or not it is a reducer.

 

The WO have nice extra touches on build quality but in my opinion are mostly cosmetic. I recommend a triplet instead, and FPL53 objective, or at least FCD100 unless cost puts that out of reach.

 

The ES scopes are very popular for giving good results for the cost, but my take is they are on the budget end for build quality also. The 2.5 hex focuser is replaced by some people for not having repeatable backlash and poor results with electronic focusers. Opinions vary, but my take is there is concensus that the FCD100 versions produce nice results but there may be focuser challenges to overcome.

 

I'm a fan of the TS-Optics Photoline triplets. They have better FPL53 glass than the FCD100 at lower cost and have better build quality and good focusers. The caveat is they must be ordered from Germany, which for me was no issue at all and I had as good or better service/shipping than I have from US companies.


Edited by OhmEye, 29 February 2020 - 09:55 PM.

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#10 h00etn

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Posted 29 February 2020 - 09:27 AM

CF does not really affect performance in any significant way at this size, other than slightly less weight. Temperature changing focus has as much or more to do with the refraction index of the glass optics changing with temperature than the material the tube is made of.

 

You will want a field flattener regardless of whether or not it is a reducer.

 

The WO have nice extra touches on build quality but in my opinion are mostly cosmetic. I recommend a triplet instead, and FPL52 objective, or at least FCD100 unless cost puts that out of reach.

 

The ES scopes are very popular for giving good results for the cost, but my take is they are on the budget end for build quality also. The 2.5 hex focuser is replaced by some people for not having repeatable backlash and poor results with electronic focusers. Opinions vary, but my take is there is concensus that the FCD100 versions produce nice results but there may be focuser challenges to overcome.

 

I'm a fan of the TS-Optics Photoline triplets. They have better FPL53 glass than the FCD100 at lower cost and have better build quality and good focusers. The caveat is they must be ordered from Germany, which for me was no issue at all and I had as good or better service/shipping than I have from US companies.

I haven't looked onto the TS Optics yet, but now I found this 'TS Optics Apochromatic refractor AP 102/520 6-Element-Flatfield Imaging Star OTA', pretty fast for a refractor. Or perhaps the slower 'TS Optics Apochromatic refractor AP 102/715 Photoline OTA'. But I can't find information about the glass, if they have the FPL-53 or not. What do you think about them? 


Edited by h00etn, 29 February 2020 - 09:28 AM.


#11 OldManSky

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Posted 29 February 2020 - 10:32 AM

I am not sure, but I have read that the carbon stops the scope from contracting, hence no need for refocusing during the night as it gets cooler outside.

 

Interesting and valuable information about the flattener issue, thank you. I will have to look more indepth on that.

 

Also heard good things about the WO, but the one I find (and that are not +3k) are only doublets....

 

Yes, I am hoping that my EQ6-R Pro will do, even with guding scpe, two cameras (ASI) and the ASIAir Pro.

The WO GT71 is an FPL53 triplet at f/5.9, And is $828 new. The adjustable reducer/flattener for it is $198, and gives you f/4.7. Results are excellent. If you want to go a little bigger, the GT81 triplet is $1198.

Neither is close to $3k.



#12 OhmEye

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Posted 29 February 2020 - 11:39 AM

I haven't looked onto the TS Optics yet, but now I found this 'TS Optics Apochromatic refractor AP 102/520 6-Element-Flatfield Imaging Star OTA', pretty fast for a refractor. Or perhaps the slower 'TS Optics Apochromatic refractor AP 102/715 Photoline OTA'. But I can't find information about the glass, if they have the FPL-53 or not. What do you think about them? 

The specs are pretty well given, and they both have FPL53.

https://www.teleskop...o-Teleskop.html

https://www.teleskop...PA-Focuser.html

 

I think the Photoline are one of the better deals in the hobby, but you do need to add a flattener or flattener/reducer. I don't have any experience with other models they have but I have no reason to believe they are different in build quality. My choice was to go with a 130mm Photoline and use a 0.79x reducer for 735mm FL at F5.5. Right now I have the reducer swapped out for a 1.0x flattener for galaxy season for 914mm F/7

 

Anyway, I just wanted to make you aware of them. I don't have any other agenda. smile.gif


Edited by OhmEye, 29 February 2020 - 11:40 AM.


#13 nimitz69

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Posted 29 February 2020 - 11:57 AM

i have the WO GT81 and their adjustable .8 reducer/FF on an EQ6R-pro -  unless someone is giving me a Tak + Mach 1 I’m keeping it ...dalek12.gif

 

scope & mount combined are under $3k


Edited by nimitz69, 29 February 2020 - 11:58 AM.

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#14 Stelios

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Posted 29 February 2020 - 12:38 PM

If you are thinking of $2K scopes, then get a Stellarvue SVX80T and call it a day. You will not find better.

 

Some points for you to ponder:

 

1) Carbon Fiber is a negative in refractors. The optics changes but the tube stays rigid, magnifying distortions as the atmosphere cools and making it harder to stabilize. 

 

2) The focuser the refractor comes with is VERY important. Mediocre focusers will have to be replaced sooner or later, at significant cost. You will want, sooner or later, to add auto-focus. Also a large (3" in the Stellarvue) focuser allows you to cover a full-frame sensor when you eventually get one.

 

3) The way the scope attaches to the mount is very important. Solid rings and a Losmandy dovetail are the way to go (the mounting on the Orion you showed is pathetic). The riser blocks of the Stellarvue are great for being able to use big cameras, filter wheels and/or focuser motors without any risk of equipment hitting the mount as the meridian is approached. 

 

4) The SVX comes with (no extra charge) a dedicated flattener. Performance of the flattener is *extremely* important--with a poor one, you will constantly need to crop.

 

5) The *only* disadvantage of a 480mm scope is that it has limited reach for small targets such as smaller galaxies and planetary nebulae. But no one scope does it all, and an 80mm F/6 refractor is a perfect place to start imaging and will remain useful well into your old age. 

 

6) The difference between FCD-100 and FPL-53 won't mean anything in real life. Both can make excellent optics for astrophotography. 

 

If the SVX is too pricey for you, then go for the TS Optics scopes, paying attention to focuser and rings.


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#15 WadeH237

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Posted 29 February 2020 - 03:06 PM

If you are thinking of $2K scopes, then get a Stellarvue SVX80T and call it a day. You will not find better.

This is a good suggestion.

 

I have the Stellarvue SV80ST.  It came with a test report of .98 Strehl and I've been really happy with it.  It doesn't have the dedicated flattener, but I bought both the Stellarvue flattener and reducer/flattener at the same time that I bought the scope, so I can run at either 480mm or 384mm focal length.



#16 h00etn

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Posted 04 March 2020 - 07:09 AM

Thanks for all suggestions. However I am not seeing any suppliers here in Europe for Stellarvue refractors. I think I will settle for the ES APO 102/714 CF ED.




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