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What ~600mm focal length scope for imaging

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#1 hoa101

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Posted 25 February 2013 - 10:04 AM

This post could easily go in the mount or CCD imaging categories as well, so hopefully this is the right spot for it.

Anyway, I'm interested in acquiring a scope with a focal length of around 600mm for imaging. Probably 90-100mm because 80mm becomes too slow. The AT90EDT looks awesome except that it is heavy. With my current imaging gear that would be fine. My guidescope and SSAG only weighs 1.3 lb and the Canon is slightly over 1 lb.

I plan to get a CCD and filter wheel at some point in the distant future. I am worried that the Sirius won't handle the weight of a larger imaging train with such a heavy scope.

On the other hand I have heard that people image on a Sirius with a C8 SCT, which is about the same weight...

Does anyone have any advice or real-world experience that might help my decision? There are some other, lighter scopes out there as well, but the AT90 is a really good deal price-wise.

Thanks!

#2 terry59

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Posted 25 February 2013 - 10:27 AM

My Sirius images well with about 22 lbs total gear. What CCD camera and filters? That wll make a difference not only on the mount but the focuser as well. I would recommend a threaded setup instead of compression so maybe take a look at the Stellarvue options.

#3 hoa101

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Posted 25 February 2013 - 10:42 AM

I was thinking 5 lb minimum for CCD, filter wheel, and field flattener, because who knows what I'll end up with in the end. Almost 4 lb heavier than my current DSLR by itself.

I have heard on CN that the 90EDT can support 6-8 lb. Hopefully that is accurate, otherwise that would alter the decision somewhat.

#4 mmalik

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Posted 25 February 2013 - 10:56 AM

How about 530mm f/5 astrograph like this....

Some CCD consideration here.... Thx

#5 hoa101

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Posted 25 February 2013 - 11:04 AM

Yes, I know, that scope is amazing. And with the reducer/extender is basically three scopes in one. I think anyone on these forums would agree it is the holy grail of imaging refractors. However, it is almost certainly too pricey, especially considering the investment I'll have to make when I buy CCD and filters someday.

How about 530mm f/5 astrograph like this....

Some CCD consideration here.... Thx



#6 Fogboundturtle

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Posted 25 February 2013 - 11:06 AM

How about 530mm f/5 astrograph like this....

Some CCD consideration here.... Thx


how about the new Esprit 80m Triplet + Flattener ? it will be an F5 scope and the price is 999$. Should be available next month

#7 hoa101

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Posted 25 February 2013 - 11:57 AM

Very cool-looking scope, especially at f/5. However, it's basically the same focal length as my AT65EDQ.

how about the new Esprit 80m Triplet + Flattener ? it will be an F5 scope and the price is 999$. Should be available next month



#8 Fogboundturtle

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Posted 25 February 2013 - 12:11 PM

Very cool-looking scope, especially at f/5. However, it's basically the same focal length as my AT65EDQ.

how about the new Esprit 80m Triplet + Flattener ? it will be an F5 scope and the price is 999$. Should be available next month


80mm @ F5 > 65mm @ F6.5

#9 snommisbor

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Posted 25 February 2013 - 12:13 PM

Best buy out there is a TV-101 or an NP-101 from TeleVue. Pretty much in the league of a FSQ106 and can be had for around 1500 for the TV101 and around 2000-2500 for a NP101 if you are patient sometimes under 2K. Remember yo are saving the cost of a FF with that scope.

#10 hoa101

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Posted 25 February 2013 - 01:02 PM

I want to point out that the title of my thread was "~600mm focal length scope..."

I really appreciate the help, but I'd like to stay on topic if possible. Thank you!

The televue scopes are definitely a consideration. I heard there was some sort of controversy about the TV-101. What was up with that?

Very cool-looking scope, especially at f/5. However, it's basically the same focal length as my AT65EDQ.

how about the new Esprit 80m Triplet + Flattener ? it will be an F5 scope and the price is 999$. Should be available next month


80mm @ F5 > 65mm @ F6.5



#11 Thomas Karpf

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Posted 25 February 2013 - 01:18 PM

While not exhaustive, here are a few refractors with focal lengths between 550 and 650mm. The list is sorted by price.

Orion ED80
StellarVue SV80ED-1
StellarVue SVR-80ED
StellarVue SV-80ED Deluxe
William Optics Megrez 90
Vixen ED86S
Astronomy Technologies AT90EDT
StellarVue SVR-90T Raptor
Televue TV-85
William Optics FLT-98 DDG
StellarVue SV-90TBV
StellarVue SV-90TF

#12 Fogboundturtle

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Posted 25 February 2013 - 03:52 PM

I want to point out that the title of my thread was "~600mm focal length scope..."

I really appreciate the help, but I'd like to stay on topic if possible. Thank you!

The televue scopes are definitely a consideration. I heard there was some sort of controversy about the TV-101. What was up with that?

Very cool-looking scope, especially at f/5. However, it's basically the same focal length as my AT65EDQ.

how about the new Esprit 80m Triplet + Flattener ? it will be an F5 scope and the price is 999$. Should be available next month


80mm @ F5 > 65mm @ F6.5


You might want to consider than the 100ED version (550mm)?

http://ca.skywatcher...ail.php?sid=419

#13 ghataa

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Posted 25 February 2013 - 08:17 PM

SV 90mm carbon fiber raptor. FL 630 mm f6.8

#14 MrGrytt

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Posted 25 February 2013 - 09:30 PM

I have no idea what your price limit might be but it almost sounds like you're describing the TEC 110FL with a focal length of 616mm @ f/5.6. There is a dedicated field flattener for it that can be purchased.

Harvey

#15 Skyshooter

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Posted 25 February 2013 - 10:37 PM

+1 on the Stellarvue SVR90T. It's 630mm FL at F/7. I use an inexpensive astro tech 2" ATFF flattener. Some example images here: www.flicker.com/photos/stargzr2011/

#16 microstar

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Posted 25 February 2013 - 11:07 PM

+1 on the Stellarvue SVR90T. It's 630mm FL at F/7. I use an inexpensive astro tech 2" ATFF flattener. Some example images here: www.flicker.com/photos/stargzr2011/


+2
I have one of these as well. Light weight with CF tube. Great optics. Nice image scale.
...Keith

#17 orlyandico

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Posted 26 February 2013 - 12:16 AM

My 2c.. try to get one which already has a Feathertouch focuser. At some point you will grow tired of the stock focuser (unless it's the Tak 106) and a Feathertouch retrofit is $400.

I believe most of the SV scopes already have the Feathertouch or the new 2.5" SV rack and pinion. I don't know how good the SV R&P is. I have the AT90EDT with the 2.7" R&P and... while it is strong enough to lift a lot of camera and it doesn't slip, it does have some focus shift when reversing direction. In other words, it ain't a Feathertouch.

But seeing as I got my AT90 (used) for 2X the price of a Feathertouch, I'm not really complaining..

#18 hoa101

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Posted 26 February 2013 - 08:50 AM

I'm still worried about the weight of the AT90EDT on my mount. My AT65 with dovetail, spacer, SSAG/finder scope, camera, etc. weighs in at slightly less than 10 lb. The AT90 is 8 lb heavier, which is getting up there if I plan to also replace the camera with CCD/filters someday.

The TMB92SS looks pretty good at f5.5 - comes with the feathertouch as well. I may hold off though on this though, since it seems I won't be satisfied with a scope that is less than ~$2k. The Raptor is nice for sure, but a touch slower than I would prefer.

#19 bouffetout

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Posted 26 February 2013 - 09:27 AM

Stellarvue SVR90T I think the carbon fiber is still on sale at $1500.

#20 Jason B

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Posted 26 February 2013 - 09:28 AM

I don't think the AT90EDT would be a bad match for your mount. Just make sure everything is balanced. I imaged with my AT111 on a AS-GT with a small guidescope until I had the finder without any issues. I think you would be ok.

Balance will be critical but I don't see a problem with the AT90/Sirius set up, IMHO, of course.

#21 Skyshooter

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Posted 26 February 2013 - 10:48 AM

As I understand it the SVR90T that is on sale has the Stellarvue SV25 2.5" R&P focuser. I've read a little on these and they seem to be much better than the old crayfords that came as standard equipment on these scopes years ago. I agree about the FT focuser as that is what I have on mine. The scope on sale with the SV25 wouldn't be too bad though. The only downside is that the SV25 has no easy robo focus option that I know of. Other than that reports are positive on the SV25.

Cheers,
Ed

#22 microstar

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Posted 26 February 2013 - 12:53 PM

The only downside is that the SV25 has no easy robo focus option that I know of. Other than that reports are positive on the SV25.

Cheers,
Ed


I ordered the Rigel Systems USB-nStep and stepper motor. It's an absolute positioning focuser motor the has an ASCOM driver for autofocus. Leon of Rigel Systems assured me that he has a model that works with the SV25, but I haven't received it yet so can't confirm. I did have someone on the MainSequenceSoftware Yahoo group confirm that the nStep will do autofocus with Sequence Generator Pro.
...Keith

#23 Gray

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Posted 26 February 2013 - 04:30 PM

I recommend the iOptron Versa 108mm ED scope. Focal length is 660 mm at F/6.1. I ordered it a few weeks ago and have had it out about seven times. It is an awesome scope. I haven't had time to start my review yet, but I can tell all that color correction is superb visually. I will hook my Cannon up for the review. It's a bit pricey but I chose it over the SV110 for several reasons. Astronomics provided me with an excellent 0.8x FF/Reducer for F/6 scopes that seems to be a perfect match for this scope.

#24 hoa101

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Posted 27 February 2013 - 09:12 AM

I'd wonder about the viability of the focuser for imaging and how much vignetting you get with the reducer. I'd be really interested to see high-res crops of the corners when you try it with your DSLR.

I did read that it is FPL-51 glass though. Maybe a little bit of color compared to the -53 scopes.

I recommend the iOptron Versa 108mm ED scope. Focal length is 660 mm at F/6.1. I ordered it a few weeks ago and have had it out about seven times. It is an awesome scope. I haven't had time to start my review yet, but I can tell all that color correction is superb visually. I will hook my Cannon up for the review. It's a bit pricey but I chose it over the SV110 for several reasons. Astronomics provided me with an excellent 0.8x FF/Reducer for F/6 scopes that seems to be a perfect match for this scope.


In any case I keep coming back around in my head to the TMB92SS. The focal length is a little shorter, but it is fast and comes with the really nice feathertouch focuser.

#25 Gray

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Posted 27 February 2013 - 10:49 AM

I wasn't planning on using the reducer with a dslr, just my ccd, but thats an option. I haven't imaged with my cannon since the ccd came. It's a capable camera though. It's been my experience that no matter what anyone else says, usually if you already have it in your head what you want then that is what you will most likely get and if you don't you would most likely regret later, especially if you have problems. I was looking at the 92 as well, but I'm not willing to wait for that one. It's a FINE looking scope. The quality of my Versa is better than any-other scope I own or have owned. It must have a great matching element because the FPL-51 glass is not a flaw. Thanks for the suggestion of using the reducer in my review. That's a great idea; reviewing both new products at once. Clear Skies to you and good luck with your purchases :)






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