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Refractor on order- cancel and go bigger or get a second different scope?

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#26 xonefs

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Posted 05 October 2020 - 08:05 PM

I would suggest actually buying a very good 70-80mm APO, and skip the 102mm, and later get the 130-140mm after you come up to speed.  As I mentioned earlier, I think the 102mm is a tweener and will not be used for AP in the long run.

Yet you have two in your signature?



#27 mmalik

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Posted 05 October 2020 - 08:20 PM

This is purely for astrophotography, and I would like to eventually be able to get some high resolution shots zoomed in on DSOs that fill the frame to the edges with nebulosity so idk if a refractor will get me there.

What is your AP background? Starter/intermediate/expert? Have you done long or short FL imaging thus far? Regards



#28 SilverLitz

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Posted 05 October 2020 - 10:40 PM

Yet you have two in your signature?

Yes, that is why I recommend skipping 100mm class, UNLESS it is Esprit 100 or Tak FSQ106.

 

Esprit 100 is much faster at f/5.5 native, and I mainly shoot it at 413mm FL w/ 0.75x FR/FF.  So the Esprit 100 is basically a faster, higher resolving 80mm in practicality.   It is a very useful scope for AP.  

 

The ES ED102CF was my 1st scope, and after a couple of months it was clear that it was not a good scope for AP.  Its focuser was very substandard, getting out of collimation very easily causing strange star shapes, its FCD1 glass had bad CA, and the FL did not fit many targets.  So I was looking at higher quality 80mm scopes to replace it.  I looked at Stellarvue SVX080T-3SV, but they were unavailable and then SV raised their prices and had problems getting the 0.74x FR/FF to work.  Then I got a good opportunity to get the Esprit for only $100-200 more, so I bought the Esprit.



#29 xonefs

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Posted 05 October 2020 - 10:57 PM

Ok. I'm just having a hard time understanding why an 80mm or shorter focal length 100 would be so much more useful than 100mm. We're talking about ~400mm vs 500mm reduced and f4.4 vs f5. 

 

Differences in camera sensor size can make a bigger difference in image scale/field of view and higher QE cameras can make a bigger difference in time for data acquisition than the minor difference in f ratio. I already have an imx455 based camera and plan to get a 2600mm whenever it is released. Even at aps-c sized I wouldn't want to go any shorter on focal length as it's just wasted space on most of the sensor for most targets. 


Edited by xonefs, 05 October 2020 - 11:05 PM.


#30 Tom Masterson

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Posted 05 October 2020 - 11:05 PM

"svx 130t which is a real dream scope, and wouldn't leave me with doubts if I should have gone bigger."

 

There's your answer right there.

 

Back in the mid 1980s I was trying to decide between a 5" or 6" AP Triplet. Figured the 5" would be great but always dreamed of owning a 6". Went with the 6" and it's still my dream scope.

 

Get your dream scope.


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#31 xonefs

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Posted 05 October 2020 - 11:13 PM

I've decided I'm just going to stick with the 102 for now, I've ended up spending a lot more money on other stuff to go with it already- more since I made this thread. I'll just have to have a new dream scope and pair it with a SVX 140 or 150 one day.


Edited by xonefs, 05 October 2020 - 11:14 PM.

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#32 bobzeq25

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Posted 05 October 2020 - 11:17 PM

Yet you have two in your signature?

It's all about learning.  The big scope gets in your way, the small scope facilitates learning.

 

I also have multiple refractors, 70, 100, 130.  I bought the 130 after I had 3 years of experience.  There's a large difference between the best setup for an experienced imager and the best to learn on.

 

One analogy is a Formula One car.  They go very fast around the track.  And you'd be crazy to try to start a racing career with one.

 

Bottom line.  You made a good decision.


Edited by bobzeq25, 05 October 2020 - 11:19 PM.


#33 SonnyE

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Posted 05 October 2020 - 11:29 PM

I've been doing my best with my ED80T CF since I started.

But now I'd like to have something bigger, and Piggy-back the two telescopes.

 

So I think you made a good decision. Do your best and learn with the 102, then later on if you want something bigger, go for it.

By then, maybe you will have seen and experienced what a bigger aperture offers through friends. 

Or decide you are perfectly happy with the 102.... cool.gif



#34 Ralph Paonessa

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Posted 05 October 2020 - 11:51 PM

IP is not about dream scopes, it's about dream mounts ...

Jon, that's brilliant! (I'm going to remember that quote.)

 

I've decided I'm just going to stick with the 102 for now, I've ended up spending a lot more money on other stuff to go with it already- more since I made this thread. I'll just have to have a new dream scope and pair it with a SVX 140 or 150 one day.

"Spend 70% of your astrophotography budget on the mount."  (--advice I received)

 

That was good advice, and I think you'll be perfectly happy with 102mm (or 80mm; or 130mm). The advice in various places above to start with a short focal length scope is also good. When I first got started reading and dreaming about astrophotography, my desire was for a 14" SCT so I could go after all those wonderful little galaxies. I am soooo glad I did not fall down that rabbit hole. (In fact, I bought an Orion Atlas mount, and my first "refractor" was a Canon EF 200mm f/2.8 lens for well over a year. A great way to learn.)

 

I've since graduated to a 106mm refractor. The focal length (which determines the field of view, along with your chip size) is sometimes too long ... and sometimes too short ... and often just perfect! The trick is to learn which targets are framed nicely with your system, and don't get hung up on the ones that aren't; you can always get a different scope/FOV down the line.

 

Ralph

 

P.S. That 130mm would have been a great scope, but the extra focal length would have made your intro to AP more difficult.



#35 rexowner

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Posted 06 October 2020 - 12:44 AM

FWIW, IMO the 102 is a good choice.

 

I was going through a similar decision.  Also considered larger scopes, and decided

to keep with the more compact scope. 

 

NP-127is - not heavy for the scope itself.

 

It wasn't the scope that's the issue, it was the mount. 

 

The 102 should work out great.  If your needs change, it's a great scope, and you can

go from there.



#36 Suavi

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Posted 06 October 2020 - 03:08 AM

I've decided I'm just going to stick with the 102 for now, I've ended up spending a lot more money on other stuff to go with it already- more since I made this thread. I'll just have to have a new dream scope and pair it with a SVX 140 or 150 one day.

Cmgratulations! I'm sure you will have fun with astrophotography and a 4" will provide with years of fun for sure. Looking forward to seeing your images waytogo.gif



#37 Jon Isaacs

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Posted 06 October 2020 - 05:51 AM

IMO, one of the costlier things you can do in this hobby is to underbuy a scope.  Some might argue and thats fine.  But, if you really want a 130mm scope then get it.  Dont buy a 102mm scope because you know whats going to happen after a few sessions. wink.gif.

 

Now, we are all human and have budgets so dont go crazy if it wont work.  But if you have the resources and are comfortable with the larger purchase then do it NOW.

 

There are a number of things that might happen.  Here's two:

 

- Gosh I wish I can purchased the larger scope.

 

- Man, this thing is great, it's a perfect size, has excellent optics, gives great views, it's "grab and go", I am sure glad I didn't buy the larger scope.

 

Jon



#38 jouster

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Posted 06 October 2020 - 06:53 AM

Another factor is where you'll be imaging. Moving up from a 102 to a 130 doesn't sound like much--it's just another ~30mm, right? When my 130 arrived I was surprised by how much bigger and heavier it was than my 102. Not a big deal when it's lying on the living room floor after the unboxing video but certainly a factor in a dark field at 2:00am with a soaking tube. Unless you have a permanent site I'd have recommended the 102, so I think you made the right choice.



#39 SilverLitz

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Posted 06 October 2020 - 07:50 PM

It all comes down to FoV and image scale, both are determined by scope FL and camera's sensor size and pixel size.  Determine what targets you want to shoot and the best scope FL for the target depends on the sensor size.  If it is a small target vs. your sensor's FoV, then image scale comes into play to give the resolution needed for tight crops.

 

Check out this spreadsheet that I created with many targets and the optimal FL depending on the camera (I have several popular camera sizes in different columns) and the amount of FoV margin around the tightest dimension (I typically use 20% margin).

 

The spreadsheet also estimates the best time of year for the targets and their meridian altitude.

 

Attached File  Astro Targets.xlsx   24.5KB   15 downloads

 

From this you can get an idea regarding good FL and camera sizes.  You will find that you will want multiple scopes/cameras to shoot all the targets you want.  For me, I use my Esprit 100 at 413mm for the majority of medium targets, EdgeHD 925 at f/7 for the small targets, and camera lenses for the very big targets (Canon EF300mm f/2.8L, 200mm f/2.8L, Samyang 135mm f/2).  My current camera is the ASI183mm-Pro, which is great for the Esprit and camera lenses, but I plan on getting an ASI2600 mono (not out yet) for my EdgeHD, as it needs larger pixels than the 183.


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#40 John Fitzgerald

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Posted 06 October 2020 - 08:05 PM

IMO, one of the costlier things you can do in this hobby is to underbuy a scope.  Some might argue and thats fine.  But, if you really want a 130mm scope then get it.  Dont buy a 102mm scope because you know whats going to happen after a few sessions. wink.gif.

 

Now, we are all human and have budgets so dont go crazy if it wont work.  But if you have the resources and are comfortable with the larger purchase then do it NOW.

If your mount will handle it, and you can swing it, go with a 150mm class.  You won't regret, once you use it.



#41 xonefs

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Posted 06 October 2020 - 09:20 PM

It all comes down to FoV and image scale, both are determined by scope FL and camera's sensor size and pixel size. Determine what targets you want to shoot and the best scope FL for the target depends on the sensor size. If it is a small target vs. your sensor's FoV, then image scale comes into play to give the resolution needed for tight crops.

Check out this spreadsheet that I created with many targets and the optimal FL depending on the camera (I have several popular camera sizes in different columns) and the amount of FoV margin around the tightest dimension (I typically use 20% margin).

The spreadsheet also estimates the best time of year for the targets and their meridian altitude.

Astro Targets.xlsx

From this you can get an idea regarding good FL and camera sizes. You will find that you will want multiple scopes/cameras to shoot all the targets you want. For me, I use my Esprit 100 at 413mm for the majority of medium targets, EdgeHD 925 at f/7 for the small targets, and camera lenses for the very big targets (Canon EF300mm f/2.8L, 200mm f/2.8L, Samyang 135mm f/2). My current camera is the ASI183mm-Pro, which is great for the Esprit and camera lenses, but I plan on getting an ASI2600 mono (not out yet) for my EdgeHD, as it needs larger pixels than the 183.


This is useful- but yeah that only comfirms what I’m saying- that I could easily go longer focal length than the 102 for optimum framing of medium targets on my sensor.

I have a sony a7riv which is basically a zwo 6200mc, and I also plan to get a 2600mm when it comes out.

I have a redcat already for very wide.

#42 Tom Masterson

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Posted 06 October 2020 - 10:45 PM

I've decided I'm just going to stick with the 102 for now, I've ended up spending a lot more money on other stuff to go with it already- more since I made this thread. I'll just have to have a new dream scope and pair it with a SVX 140 or 150 one day.

Darn, I had so much fun trying to spend someone else's money. Kinda like the kid up on the cliff above the local swimming hole urging his frightened friend to "Go ahead, Jump!" 



#43 xonefs

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Posted 07 October 2020 - 12:04 AM

Darn, I had so much fun trying to spend someone else's money. Kinda like the kid up on the cliff above the local swimming hole urging his frightened friend to "Go ahead, Jump!" 

I'm sure I'll want more soon. I need to draw the line somewhere for now but this dopamine rush of consumerism won't last forever and I'll need the next hit.

 

I picked the worst hobby to get into now. I usually go for expensive hobbies- but there's limits on them and I always feel like the best stuff is almost all kind of in reach for several thousand or maybe 10k. Astronomy has no end in sight or feeling like you can reach top and you can literally spend a million dollars on a home observatory.  


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#44 John Fitzgerald

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Posted 07 October 2020 - 08:23 AM

It's no worse than bass tournament fishing or 1/4 scale rc airplane hobbies.


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#45 xonefs

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Posted 16 October 2020 - 01:55 PM

This thing looks impressive....

 

VRCu02w.jpg

 

gJDgMqd.jpg

 

Ypk5ZUP.jpg

 

uTJQICz.jpg


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#46 HydrogenAlpha

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Posted 18 October 2020 - 09:11 AM

I personally don't find using a 5" scope any different from using a small refractor. I still run the same default settings on autoguiding and perform drift alignment as I would on both a large and small scope. 

 

The only difference is the former requires a larger mount than the latter. But this is more a matter of affordability vs the need to build up a technical skill. 




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