Advice on a little telescope for the Star Adventurer

[Astro Buer]

Hi all! 

I'm looking for any recommendations for a good little refractor as a companion for my Star Adventurer for astrophotography. 

Little (in weight) being the operative word given the 5kg payload capacity of the mount! 

Currently I am shooting with an Sony A7S and guiding with an Orion Starshoot and Orion 50mm guide scope. So there's a little bit of weight on there already. 

Looking at refractors with a focal length of 400-600mm which are proven performers for imaging. 

So far contenders are:
Stellarvue 80mm ED
TS-Optics ED 70mm f/6
William Optics Gran Turismo 71 APO Refractor

Any advice/images of rigs/example images/etc would be greatly appreciated! 

Thanks in advance :-) 

 

[Guest]

Good evening! If i could give to you my answer, then have a look to this little but sharp and portable (2kg only) F4.9 with built in corrector or also called flat field APO.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p7085_TS-Optics-Imaging-Star71---71-mm-f-4-9--Flat-Field-APO.html

 

 

Good luck, Martin

[Scooot]

Don't know what your budget is but the star adventurer easily carries my tak fs60CB. Its also ok when I add the extender which converts it from an f5.9 to f10.

[AdamT]

A little under 400mm but have you considered a WO ZS61.

[Astro Buer]

1 hour ago, artem said:

Good evening! If i could give to you my answer, then have a look to this little but sharp and portable (2kg only) F4.9 with built in corrector or also called flat field APO.

https://www.teleskop-express.de/shop/product_info.php/language/en/info/p7085_TS-Optics-Imaging-Star71---71-mm-f-4-9--Flat-Field-APO.html

 

 

Good luck, Martin

Thanks for this Martin! I like the fact it is '..a 100% photo telescope' and no extra accessories needed, it is at the top end of my budget though! but thank you, a strong contender if I can afford it  

 

Thank you for your reply! 

[Astro Buer]

1 hour ago, Scooot said:

Don't know what your budget is but the star adventurer easily carries my tak fs60CB. Its also ok when I add the extender which converts it from an f5.9 to f10.

This looks great also, I do like the idea of being able to extend and still use with the SW, even at the loss of aperture... sorry for my naivety but would you recommend using the field flattener also? are field flatteners a 'must' for imaging? and if so, can this be used in conjunction with the extender? 

Thanks so much for your reply, it means a lot to a beginner like me! 

[Astro Buer]

1 hour ago, AdamT said:

A little under 400mm but have you considered a WO ZS61.

Thanks for your reply AdamT! what a lovely compact little setup (I'm a bit of a sucker for the WO product line I'll admit) are there any accessories you would recommend with this scope? 

Looks fantastic though, as all the replies have been so far. 

Thanks so much  

[Scooot]

31 minutes ago, Astro Buer said:

This looks great also, I do like the idea of being able to extend and still use with the SW, even at the loss of aperture... sorry for my naivety but would you recommend using the field flattener also? are field flatteners a 'must' for imaging? and if so, can this be used in conjunction with the extender? 

Thanks so much for your reply, it means a lot to a beginner like me! 

I don't think you lose aperture when extending but maybe I'm mistaken? The extender inserts into the OTA and increases the focal length from 355mm to 600mm. I do use the tak field flattener but I'm not an experienced imager so not qualified to advise I'm afraid. I also use it with the extender although I must confess I'm not sure whether I should or not. Most of my imaging has been of the moon wth it. I bought it from Ian King who I'm sure would give good advice if you were interested. Its a very versatile setup, I've been considering on and off getting the 76mm objective upgrade at some point as well. So it can be converted to a 76mm refractor although I'm not sure the Sky Adventurer would be able to handle that.

On the negative side I have read comments that the blue signal is not quite right, or maybe as good as it should be, for deep Sky imaging. I think it was Olly that pointed this out.

Edited October 9, 2017 by Scooot

[Adam J]

I know someone who uses this scope to great effect on the Star Adventurer:

http://www.365astronomy.com/TS-INED-APO-70-420mm-Carbon-Fiber-Tube-2-Micro-Crayford-Focuser.html

I think that a ZS61 is also a great choice though at a little shorter focal length.

[Guest]

10 hours ago, Astro Buer said:

Thanks for this Martin! I like the fact it is '..a 100% photo telescope' and no extra accessories needed, it is at the top end of my budget though! but thank you, a strong contender if I can afford it  

 

Thank you for your reply! 

Hello Astro Buer, I actually have this small piece of biest  and it is a light machine F4.9, beside many others factors but one main reason did make me buy this APO!  the fact that you must not play around with millimeter adapters to find or reach the perfect focus "a 5 element flat field APO", all you need to do is attach your CCD & EOS or NIKON to the APO and focus with a BAHTINOV MASK until you have the perfect star and you are done.. the Focuser can handle heavy CCD also " I use SBIG ST10XME + FW " is a heavy piece of CCD but also use a CANON 600D-a..

Cheers

Martin

 

[Astro Buer]

10 hours ago, Scooot said:

I don't think you lose aperture when extending but maybe I'm mistaken? The extender inserts into the OTA and increases the focal length from 355mm to 600mm. I do use the tak field flattener but I'm not an experienced imager so not qualified to advise I'm afraid. I also use it with the extender although I must confess I'm not sure whether I should or not. Most of my imaging has been of the moon wth it. I bought it from Ian King who I'm sure would give good advice if you were interested. Its a very versatile setup, I've been considering on and off getting the 76mm objective upgrade at some point as well. So it can be converted to a 76mm refractor although I'm not sure the Sky Adventurer would be able to handle that.

On the negative side I have read comments that the blue signal is not quite right, or maybe as good as it should be, for deep Sky imaging. I think it was Olly that pointed this out.

Sorry, I think I'm getting my terminology mixed up regarding apertures! (Thinking in DSLR world!) Thanks for your honest review  definitely given me food for thought. 

[Astro Buer]

8 hours ago, Adam J said:

I know someone who uses this scope to great effect on the Star Adventurer:

http://www.365astronomy.com/TS-INED-APO-70-420mm-Carbon-Fiber-Tube-2-Micro-Crayford-Focuser.html

I think that a ZS61 is also a great choice though at a little shorter focal length.

Thanks Adam J! At 3.4kg I thought that might be tipping the scales a little with the guidecam on there as well. But maybe I'm being a little too cautious as to not overload the mount... but as it's been a success for your friend that's encouraging for me. 

Looks like a lovely little scope at a good price! Thanks for your advice! I really appreciate it  

[Astro Buer]

20 minutes ago, artem said:

Hello Astro Buer, I actually have this small piece of biest  and it is a light machine F4.9, beside many others factors but one main reason did make me buy this APO!  the fact that you must not play around with millimeter adapters to find or reach the perfect focus "a 5 element flat field APO", all you need to do is attach your CCD & EOS or NIKON to the APO and focus with a BAHTINOV MASK until you have the perfect star and you are done.. the Focuser can handle heavy CCD also " I use SBIG ST10XME + FW " is a heavy piece of CCD but also use a CANON 600D-a..

Cheers

Martin

 

Thanks for the advice Martin! And yes, good to know about the focussing... anything to make life easier given that AP is a fairly steep learning curve! 

Thanks again!  

[Adam J]

7 hours ago, Astro Buer said:

Thanks Adam J! At 3.4kg I thought that might be tipping the scales a little with the guidecam on there as well. But maybe I'm being a little too cautious as to not overload the mount... but as it's been a success for your friend that's encouraging for me. 

Looks like a lovely little scope at a good price! Thanks for your advice! I really appreciate it  

huum thats odd I see it listed as only 2.1kg for the OTA only? I have never been too sure about guiding on a star adventurer to be honest I am not sure how well guiding will work in RA only. My friend does not guide his setup so I cant comment on how well it copes once you add the weight of a guide camera. He uses a 1100D so its fine for 2 min subs with the camera / flatter / OTA.  Maybe with one of those 30mm QHY guide scope packages???

[AdamT]

20 hours ago, Astro Buer said:

Thanks for your reply AdamT! what a lovely compact little setup (I'm a bit of a sucker for the WO product line I'll admit) are there any accessories you would recommend with this scope? 

Looks fantastic though, as all the replies have been so far. 

Thanks so much  

I would recommend getting the flat 61 with a full frame or APS-c. I also had to get an M48 DLSR adaptor as the spacing is critical, You may need an additional spacer if you sony is mirrorless. Its a great little scope not sure id want to go any longer on the SA, but i haven't guided on it yet and if i was going to do it i may as well get the AZ-EQ6 out, saying that i have seen a few people getting good results using 400mm lenses and guiding the RA to limit the PEC.

Also worth mentioning that you can screw a 2" light pollution filter in the flattener and its got a nice built in rotator, everything screws together so no compression rings with is also a nice touch. 

[Astro Buer]

6 hours ago, Adam J said:

huum thats odd I see it listed as only 2.1kg for the OTA only? I have never been too sure about guiding on a star adventurer to be honest I am not sure how well guiding will work in RA only. My friend does not guide his setup so I cant comment on how well it copes once you add the weight of a guide camera. He uses a 1100D so its fine for 2 min subs with the camera / flatter / OTA.  Maybe with one of those 30mm QHY guide scope packages???

Yes, my bad. I was looking at the weight at the very top of the listing which makes it a little confusing...! I don't expect hubble-esque results with the Star Adventurer and guiding! but I feel it is going to be a good way to at learn, and the guiding equipment can be used on better scopes and mounts should I upgrade in the future. 

Thanks for your help! 

Baby steps  

[Astro Buer]

3 hours ago, AdamT said:

I would recommend getting the flat 61 with a full frame or APS-c. I also had to get an M48 DLSR adaptor as the spacing is critical, You may need an additional spacer if you sony is mirrorless. Its a great little scope not sure id want to go any longer on the SA, but i haven't guided on it yet and if i was going to do it i may as well get the AZ-EQ6 out, saying that i have seen a few people getting good results using 400mm lenses and guiding the RA to limit the PEC.

Also worth mentioning that you can screw a 2" light pollution filter in the flattener and its got a nice built in rotator, everything screws together so no compression rings with is also a nice touch. 

I have to say I am leaning towards the WO ZS61. Good optics and a good focal length for a modest mount like the Star Adventurer. You're right I would need a few adaptors to connect my A7S to the flattener. An M48 to T2, then an E Mount to T2 adaptor as well if my research is correct? 

http://www.365astronomy.com/Adapter-from-M48-2-inch-filter-thread-to-T2-Low-Profile.html

and

http://www.365astronomy.com/365Astronomy-T-Ring-SONY-Alpha-E-Mount-Nex-T2-Lens-Adapter-Ring.html

I already have an Astronomik CLS filter clipped into my A7S, so hoping this will do the trick.

I am so close to pulling the trigger on this...

Thanks for all your advice. The SGL community is awesome  

[Adam J]

21 minutes ago, Astro Buer said:

I have to say I am leaning towards the WO ZS61. Good optics and a good focal length for a modest mount like the Star Adventurer. You're right I would need a few adaptors to connect my A7S to the flattener. An M48 to T2, then an E Mount to T2 adaptor as well if my research is correct? 

http://www.365astronomy.com/Adapter-from-M48-2-inch-filter-thread-to-T2-Low-Profile.html

and

http://www.365astronomy.com/365Astronomy-T-Ring-SONY-Alpha-E-Mount-Nex-T2-Lens-Adapter-Ring.html

I already have an Astronomik CLS filter clipped into my A7S, so hoping this will do the trick.

I am so close to pulling the trigger on this...

Thanks for all your advice. The SGL community is awesome  

The ZS61 has better optics than the TS scope i posted so if you are not bothered by the shorter focal length then go for the WO ZS61 I would do. I only noted the other scope due to you wanting over 400mm of focal length. The main difference is that the ZS61 uses FPL-53 glass so the color correction will be much better.

[Astro Buer]

2 minutes ago, Adam J said:

The ZS61 has better optics than the TS scope i posted so if you are not bothered by the shorter focal length then go for the WO ZS61 I would do. I only noted the other scope due to you wanting over 400mm of focal length. The main difference is that the ZS61 uses FPL-53 glass so the color correction will be much better.

Yes, well I had a thought earlier today that I can put my cameras in APS-C mode which when using the WO ZS61 would give me a focal length of 540mm, should I want to experiment with that... albeit at a loss of resolution. But I also have an A7R 1 and 2 (un-modded) which have much larger sensors and if I can shoot using a lower ISO (if I can get the tracking working well for longer subs) will still give me a decent resolution image to work with.

It's all just a learning curve for me, and if I can get good success by using shorter focal lengths before potentially moving on to more advanced setups and longer focal lengths, then that is a good thing for my confidence  

[ollypenrice]

I would look at it this way: the mount has a maximum payload and a maximum tracking accuracy. Both, not just one, have to be respected. Payload is obviously easy - you just weigh what you are putting on the mount. Accuracy is more difficult. The unit that matters is resolution measured in arcseconds per pixel. This value is derived from focal length and pixel size, so focal length alone is not a useful term. (Long focal length with big pixels equals short focal length with small pixels in terms of resolution, stating it simply.)

I think that the best information will come from published images in which the user states what camera, at what focal length, was being used. To turn this into arcseconds per pixel you can use a number of online calculators such as this one: http://www.12dstring.me.uk/fovcalc.php

Olly

[Adam J]

Changing to a crop frame mode from full frame will not increase your focal length, it will only reduce your field of view, the focal length stays the same. However using it in APS-C mode is probably a good idea anyway as the ZS61 is not going to fully illuminate and give you a flat frame over a full frame sensor.

The resolution will stay the same as that is governed by focal length and the pixel size, always think about arcseconds / pixel and take a look at the BBC Sky at night Field of View Calculator. The large pixels of the A7S are probably not the best match for such a short focal length and may make the stars look a little square? But to be honest its still a great camera for astro work.

[ollypenrice]

21 minutes ago, Astro Buer said:

Yes, well I had a thought earlier today that I can put my cameras in APS-C mode which when using the WO ZS61 would give me a focal length of 540mm,

The idea that focal length and chip size are related is an error imported from the daytime camera world via something called 'crop factor.' I would ignore all this completely. It is utterly meaningless. Keep it nice and simple in astrophotography and you won't go wrong. You have a focal length, determined by your scope's optics. This is a simple and non-negotiable fact. You have a chip size of x by y, also non negotiable. Then you have your pixel size, which (allied to you focal length) specifies your resolution in arcseconds per pixel. Your chip size simply speciifies how much sky you cover. It has absolutely no effect whatever on your resolution. (That derives from focal length and pixel size. The number of pixels you have is also irrelevant.)

Olly

Edit: Crossed with Adam J but we are saying the same things.

Edited October 10, 2017 by ollypenrice

[fireballxl5]

shout out for the versatility of the light-weight Tak FS60CB system - some images for your consideration at 252mm (reducer @ f4.2), 366mm (flattener @ f6.1) and 610mm (1.7x extender with flattener ~f10). Admittedly used on an AstroTrac rather than the SA...any excuse to post some of my photos 

HTH, Andy

 

Antares & Rho Oph @ F4.2

NA and Pelican @ F6.1

M20 @ F10

Sun & Moon @ F10

Edited October 10, 2017 by fireballxl5
added focal ratio info for clarity

[Scooot]

My only solar image with the little tak fs60. Here's my mercury transit with the 1.7 extender at f10 using my canon 450 on the star adventurer.

 

 

Edited October 10, 2017 by Scooot

[Astro Buer]

1 hour ago, Adam J said:

Changing to a crop frame mode from full frame will not increase your focal length, it will only reduce your field of view, the focal length stays the same. However using it in APS-C mode is probably a good idea anyway as the ZS61 is not going to fully illuminate and give you a flat frame over a full frame sensor.

The resolution will stay the same as that is governed by focal length and the pixel size, always think about arcseconds / pixel and take a look at the BBC Sky at night Field of View Calculator. The large pixels of the A7S are probably not the best match for such a short focal length and may make the stars look a little square? But to be honest its still a great camera for astro work.

Thank you, that's a great insight and I obviously have a lot of reading to do!