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Help on next scope

Astrophotography Refractor
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#1 SwimmingFish849

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Posted 19 September 2021 - 04:36 PM

Hi
I'm struggling to decide on my next scope.
I know I want to stick to a refractor and I think a triplet but I keep going back and forth between all different options

I currently have a CEM26 mount, ASI 533mc Pro, 120mm-mini for guiding and I've been using the redcat 51 up to now with the l-extreme 2" filter

Can anyone recommend a next scope? By what I can tell on various forums is people rate the 80mm refractors but I'm open to suggestions

I've been mainly doing DSO astrophotography but might want to dabble a little in galaxies too

Thanks :)

#2 blazek

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Posted 19 September 2021 - 05:44 PM

Well, as you know, your choice is defined by the payload of your mount. CEM26 is excellent light/travel mount , but large® refractors would be challenge for such small mount. So, you are right , around 80-90mm would be a good match. Even though , 100mm refractors are around 7kg , well within your mount specs, when you add camera, guider and guiding camera , eventually autofocuser, you'll be on upper side of reasonable weight for your mount. 100 mm refractors are also long (with dew shield) , so the 100mm setup will be quite wind sensitive. All in all , 80mm is safe and reasonable thinking.

Which one exactly , will be determined by the budget . As always , quality comes with the price (vice versa not always the case) .

There are many good scopes with 80-90mm aperture.  There are many good Chinese scopes (like Sharpstar) sold under various brand names at lower price , There are excellent scopes like WO or Skywatcher Esprit. with some middle prices and there are 

Takahashi, TEC, APM LZOS, which are top performers with related price points. If you ask whether radical price differences are justified by image quality differences, you'll perhaps get many different answers out which none will be neither 100% right nor 100% wrong... 

If I would be buying small refractor it would be Esprit 80.  Anyway the starting point is Triplet with FPL 53 glass .. 

 

For hunting (smaller) galaxies , small refractor is perhaps not the first choice , but is not hopeless either. 

 

Good luck with your choice and clear sky 


Edited by blazek, 19 September 2021 - 05:47 PM.

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#3 bobzeq25

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Posted 19 September 2021 - 05:59 PM

No, budget, eh?  This would be good.  $2395 w/matched flattener.

 

https://www.stellarv...0t-3sv-deposit/

 

480mm, you don't want to go much longer with that mount.  OK for big galaxies and galaxy groups.

 

More moderately priced 80 w/high quality glass and focuser.  About $1000.  You'll want a flattener, about $200.

 

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

 

https://www.teleskop...connection.html


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#4 teashea

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Posted 19 September 2021 - 08:01 PM

Hi
I'm struggling to decide on my next scope.
I know I want to stick to a refractor and I think a triplet but I keep going back and forth between all different options

I currently have a CEM26 mount, ASI 533mc Pro, 120mm-mini for guiding and I've been using the redcat 51 up to now with the l-extreme 2" filter

Can anyone recommend a next scope? By what I can tell on various forums is people rate the 80mm refractors but I'm open to suggestions

I've been mainly doing DSO astrophotography but might want to dabble a little in galaxies too

Thanks smile.gif

The mount is as important as the telescope.  You need a new mount if you are going to get a larger telescope.


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#5 drd715

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Posted 19 September 2021 - 09:23 PM

Consider the size (arc seconds) of the objects you are interested in. Match the sensor size to the framing size to determine your best focal length range. Several online calculators can do this.

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#6 bobzeq25

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Posted 20 September 2021 - 12:06 AM

Consider the size (arc seconds) of the objects you are interested in. Match the sensor size to the framing size to determine your best focal length range. Several online calculators can do this.

Sent from my SM-N950U using Tapatalk

And a small galaxy will show that you need a long focal length scope.  Which is incompatible with his CEM26 mount.

 

This is a system.  A lot of bad advice 0n CN happens when people look at just one aspect of things, and leave out critical factors.



#7 SwimmingFish849

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Posted 20 September 2021 - 03:42 AM

Thanks all for the replies.
A larger mount is in my wish list but I really wanted to get more use out of this mount before replacing it if I can

I'll have a look at some of the 80mm options suggested and see if these would work for me for a while before upgrading the mount :)

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#8 ayadai

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Posted 20 September 2021 - 03:57 AM

You may also wish to check out the Orion ED80T CF. ~US$1K, 90 days same as cash, in stock, carbon fiber 480mm f6.0 triplet with FPL-53 glass in a hard case. There's alot there to like. Note, however, that you'll need a set of US$30 rings for astrophotography (Agenaastro.com rings are identical to stock Orion and fit perfectly). I'm enjoying the heck out of mine on the rare nights it's clear. Incredibly sharp, zero CA, rigid, and very good build quality.


Edited by ayadai, 20 September 2021 - 03:57 AM.


#9 bulletdodger

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Posted 20 September 2021 - 07:51 AM

My advice would be to get a good quality ED doublet with good color correction for visual, much lighter and you could have a better weight to aperature ratio.

Good Luck in your hunt!

#10 Sacred Heart

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Posted 20 September 2021 - 09:22 AM

Hi
I'm struggling to decide on my next scope.
I know I want to stick to a refractor and I think a triplet but I keep going back and forth between all different options

I currently have a CEM26 mount, ASI 533mc Pro, 120mm-mini for guiding and I've been using the redcat 51 up to now with the l-extreme 2" filter

Can anyone recommend a next scope? By what I can tell on various forums is people rate the 80mm refractors but I'm open to suggestions

I've been mainly doing DSO astrophotography but might want to dabble a little in galaxies too

Thanks smile.gif

 

 

Thanks all for the replies.
A larger mount is in my wish list but I really wanted to get more use out of this mount before replacing it if I can

I'll have a look at some of the 80mm options suggested and see if these would work for me for a while before upgrading the mount smile.gif

Sent from my IN2023 using Tapatalk

If you are wanting another scope and it may require a bigger mount,  why not wait, take the money you have saved for the next refractor and apply it to your next mount??   You will get the mount quicker and the mount will open up choices for the next scope.    Besides, can you put a barlow on the Redcat and shoot galaxies and all the rest??

   Just asking,   Joe



#11 SilverLitz

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Posted 20 September 2021 - 09:58 AM

There will be many targets that fit an 80mm class scope, which I would agree is about the limit for your mount.  I expect a good ~80mm APO would end up being more used than the RedCat, which is a very large target scope.  No matter where you end up, you will want a scope in the 400-500mm FL range.  I think it is wise to build up from the shorter FL scope side, before going for big glass/mirrors and required bigger mount.

 

Bob's recommendation of the SVX080T packaged with FF, is probably about the best choice.  The Esprit 80 would be another good choice, though its image circle is only ~33mm, which is not a factor until sensor get bigger than APS-C, and its does not have mounting rings, but a fixed foot.  I have an Esprit 100, and love it, but it is too heavy for your mount.  Between SVX and Esprit, I would choose SVX and pay the difference, as they are hand made in the USA to a higher standard.


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#12 SwimmingFish849

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Posted 20 September 2021 - 10:01 AM

If you are wanting another scope and it may require a bigger mount, why not wait, take the money you have saved for the next refractor and apply it to your next mount?? You will get the mount quicker and the mount will open up choices for the next scope. Besides, can you put a barlow on the Redcat and shoot galaxies and all the rest??
Just asking, Joe

I don't think a barlow would work on the redcat, or so I have read anyway!

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#13 MrRoberts

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Posted 20 September 2021 - 10:04 AM

My 80mm Esprit is a great fit with my CEM25,s for vis and ap. Anything larger (100mm'ish) you will need more mount (CEM40'ish/equivalent).

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#14 gzljh96

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Posted 20 September 2021 - 03:36 PM

Hijacking thread, but may I ask how heavy the CEM26 mount is with counterweight and the tripod? I have been eyeing a light travel mount like the RST-135 or the Astrotrac 360, but those are far too expensive for me... for now.

 

Back to OP's question. An 80mm-class APO seems appropriate for your mount. If you have the money, why not consider a flourite doublet, like a Takahashi FC-76D? With the dedicated reducer it sits at 417mm/F5.5. Or the Borg 72FL/90FL which are both incredibly light for their weight class.

 

Also, if you liked the RedCat, why not go for the Redder Cat --- the upcoming RedCat 71mm/350 F4.9, featuring the same Petzval design but this time with an internal focuser --- the OTA stays the same length when it focus, apparently. No need for reducers and flatteners.

 

If the Japanese dealer Tomita (article linked above) is telling the truth, the RedCat 71 has either entered production or is very close to it. Apparently they have reserved a few early units from WO, and they are taking reservations for JPY 198k, which is about USD 1,980, per piece. Well, they were taking reservations, since they sold out their reserved units already. Give it a few months and I believe you can start ordering those in the West as well.



#15 SwimmingFish849

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Posted 20 September 2021 - 03:54 PM

Hijacking thread, but may I ask how heavy the CEM26 mount is with counterweight and the tripod? I have been eyeing a light travel mount like the RST-135 or the Astrotrac 360, but those are far too expensive for me... for now.

Back to OP's question. An 80mm-class APO seems appropriate for your mount. If you have the money, why not consider a flourite doublet, like a Takahashi FC-76D? With the dedicated reducer it sits at 417mm/F5.5. Or the Borg 72FL/90FL which are both incredibly light for their weight class.

Also, if you liked the RedCat, why not go for the Redder Cat --- the upcoming RedCat 71mm/350 F4.9, featuring the same Petzval design but this time with an internal focuser --- the OTA stays the same length when it focus, apparently. No need for reducers and flatteners.

If the Japanese dealer Tomita (article linked above) is telling the truth, the RedCat 71 has either entered production or is very close to it. Apparently they have reserved a few early units from WO, and they are taking reservations for JPY 198k, which is about USD 1,980, per piece. Well, they were taking reservations, since they sold out their reserved units already. Give it a few months and I believe you can start ordering those in the West as well.

I did wonder if that new redcat would ever come out, it looks like it could be a helical focuser again though so no auto focusing which I wouldn't mind getting into.

I think I'm a little lost on what focal length would be a good length to go to after the 250mm on the redcat

I'm happy with the cem26, it came in a handy metal case for the main unit which is easy to carry and I ordered a bag for the stand which makes it easy to carry.
Having it all put together I can still carry it in and out without the scope and accessories attached, it doesn't fit through the door very easily though! If I was to make a guess put together it's probably around 15kg

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#16 gzljh96

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Posted 20 September 2021 - 04:12 PM

I did wonder if that new redcat would ever come out, it looks like it could be a helical focuser again though so no auto focusing which I wouldn't mind getting into.

I think I'm a little lost on what focal length would be a good length to go to after the 250mm on the redcat

I'm happy with the cem26, it came in a handy metal case for the main unit which is easy to carry and I ordered a bag for the stand which makes it easy to carry.
Having it all put together I can still carry it in and out without the scope and accessories attached, it doesn't fit through the door very easily though! If I was to make a guess put together it's probably around 15kg

Sent from my IN2023 using Tapatalk

Thanks for the reply. My issue is that I don't have a car; so everytime I want to go to stargazing I will need to travel by train for at least a part of my journey. 

 

So I read that the mount head is 4.5kg and the counterweight should be 2-3kg. Then the tripod is 7-8kg? Gosh. I think all of that can barely fit in my suitcase if I try. Still, it seems that saving for the Astrotrac or the RST isn't a bad choice here... but **** those are twice and four times as expensive as the CEM respectively.



#17 bobzeq25

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Posted 20 September 2021 - 04:27 PM

I think I'm a little lost on what focal length would be a good length to go to after the 250mm on the redcat

 

With that mount I recommend 480 (common, as in 80mm F6).  Big enough change to be meaningful, small enough to not overwhelm the mount.

 

 


Edited by bobzeq25, 20 September 2021 - 04:30 PM.

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#18 bobzeq25

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Posted 20 September 2021 - 04:31 PM

Thanks for the reply. My issue is that I don't have a car; so everytime I want to go to stargazing I will need to travel by train for at least a part of my journey. 

 

So I read that the mount head is 4.5kg and the counterweight should be 2-3kg. Then the tripod is 7-8kg? Gosh. I think all of that can barely fit in my suitcase if I try. Still, it seems that saving for the Astrotrac or the RST isn't a bad choice here... but **** those are twice and four times as expensive as the CEM respectively.

I use a camera tracker in that situation.  The usual suspects, Staradventurer and iOptron Skyguider, are about $500.

 

I'd use them with a telephoto lens, or a Redcat 51/250, max.

 

More than that will cost you money for a mount.  No surprise, that.



#19 gzljh96

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Posted 20 September 2021 - 05:45 PM

I use a camera tracker in that situation.  The usual suspects, Staradventurer and iOptron Skyguider, are about $500.

 

I'd use them with a telephoto lens, or a Redcat 51/250, max.

 

More than that will cost you money for a mount.  No surprise, that.

I have a RedCat 51/250 and a Fornax Lightrack II. I am hoping to use an alt-az mount as the counterbalance kit because Fornax's kit is too expensive, but I tested it on a ballhead and I am convinced it can do 2min exposures unguided if I nail the polar alignment, even without counterweight.

 

Issue is, I suddenly find myself in possession of a Borg 90FL and many hundred pounds less in my bank account (soon) ;) For now I am only planning to use it visually on an alt-az mount, but I do intend to eventually use it for AP. The Borg 90FL weights about 2kg on its own, and with rings and everything probably approaches 2.5-3kg, with a focal length of either 540mm (with the Borg multi-flattener) or 400mm (with the much more expensive Borg flattener-reducer). The Fornax can probably manage 400mm unguided if I really nail the polar alignment, but 540mm might be too much of a stretch for it. 

 

So you are exactly right that I would need a more expensive mount to satisfy my needs; the issue is simply how much more expensive. Both the RST and the Astrotrac 360 will probably handle both scopes just fine, but the former will probably have enough capacity for whatever scope I can carry, like a C8 or something. 


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#20 teashea

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Posted 20 September 2021 - 09:43 PM

If you want to use the same mount, they you could purchase a higher quality small telescope.



#21 Domerman

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Posted 20 September 2021 - 09:59 PM

Good luck finding a scope at this point.

#22 ayadai

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Posted 20 September 2021 - 10:43 PM

Good luck finding a scope at this point.

 

 

Orion ED80T CF. ~US$1K, 90 days same as cash, in stock, carbon fiber 480mm f6.0 triplet with FPL-53 glass in a hard case.

Just sayin'...


Edited by ayadai, 20 September 2021 - 10:43 PM.


#23 Domerman

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Posted 20 September 2021 - 10:55 PM

That scope is way overpriced.

#24 ayadai

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Posted 20 September 2021 - 11:00 PM

That scope is way overpriced.

Comparative examples, please?
 



#25 AZ49

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Posted 24 September 2021 - 07:51 PM

I’ve had the pleasure of owning an SVX102T and now the SVX80T FT

 

Both are just superb. I went with the 80 for portability. I have it mounted on a SW AZGTI and absolutely love it. One hand on the mount and the other on the door. 
 

Here is a pic of it on my porch while viewing Saturn and Jupiter. I live in Bortle 5 skies and this scope does not disappoint. However, I had the chance to go to darker skies a couple weeks ago and I was just floored. I could not believe what I could see and in such detail. The sharpness and contrast were just breathtaking. 
 

I feel that the 80 showed me more in dark skies than my old 12” Meade showed in my backyard. 
 

 

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