26 replies to this topic

[Astrohoven]

I'm considering buying a small 6 inch Newtonian for imaging. I'm confused between 2 options :

 

TS Photon 6 inch F4:

 

https://www.teleskop...tall-Tubus.html

 

GSO 6 inch F4:

 

https://agenaastro.c...lector-ota.html

 

Any advice on which one might be slightly better or are they relatively the same? and can i find better options for the same price range?

 

Cheers!

 

Anthony

[Viktorious]

No knowledge of the 6" specifically. But asked teleskop-express about this for the 10" that I just bought, where they have their Photon and the white GSO (just as in your links). The answer I got was that they are the same, mirror-wise at least (since TS uses GSO mirrors). They just said that the white GSO was older stock that they still had and the black Photons are the newer stock. 

 

For me I went GSO only because something weird happened with the shipping cost when I put the Photon in the cart (95€ instead of 29€).

[JAS62]

My take is the scopes are identical.  Both are likely GSO.  I have a 6" Apertura F/4 newt which is another re-branded GSO.  It works just fine and your AVX will handle it nicely.

[Astrohoven]

My take is the scopes are identical.  Both are likely GSO.  I have a 6" Apertura F/4 newt which is another re-branded GSO.  It works just fine and your AVX will handle it nicely.

Thanks you! after some research I found out that TS uses same optics as GSO but mechanically the tubes are different. Apparently the TS secondary mirror is larger 70mm as opposed to GSO's 62.5mm and the spider vanes are thinner 0.5mm to GSO's 0.8mm in addition to other small differences. 

[OldManSky]

It looks like the TS focuser is slightly different also, which may be better (the GSO version is a "standard" Crayford, and it's sometimes difficult to get the tension enough to hold a camera-laden imaging train yet still be able to easily focus either manually or with a focus motor -- if you make the tension light enough to focus easily, the focuser will slip with the heavy camera load).

 

Other mechanical issues, it's hard to say if there's any difference.  My experience is that the very thin steel tube flexes considerably, and the scope doesn't hold collimation because of that as you move to different positions across the sky.  All versions of this scope have an open back-end (I guess to help mirror cooling) that leaks light, so if you have any light source (including LEDs from equipment) that's visible to the back of the scope, it leaks into images.

 

The optics on mine (a TPO version from OPT, but it's essentially a stock-rebranded GSO) are pretty darn good, but the mechanicals are problematic.  I have mine sitting in a case for now, because without reworking the mechanicals to better hold collimation, prevent light leaks, make the focuser better...imaging with it was very frustrating.  If the TS mechanicals are improved over the stock version, they may have solved some of those issues.

[Astrohoven]

It looks like the TS focuser is slightly different also, which may be better (the GSO version is a "standard" Crayford, and it's sometimes difficult to get the tension enough to hold a camera-laden imaging train yet still be able to easily focus either manually or with a focus motor -- if you make the tension light enough to focus easily, the focuser will slip with the heavy camera load).

 

Other mechanical issues, it's hard to say if there's any difference.  My experience is that the very thin steel tube flexes considerably, and the scope doesn't hold collimation because of that as you move to different positions across the sky.  All versions of this scope have an open back-end (I guess to help mirror cooling) that leaks light, so if you have any light source (including LEDs from equipment) that's visible to the back of the scope, it leaks into images.

 

The optics on mine (a TPO version from OPT, but it's essentially a stock-rebranded GSO) are pretty darn good, but the mechanicals are problematic.  I have mine sitting in a case for now, because without reworking the mechanicals to better hold collimation, prevent light leaks, make the focuser better...imaging with it was very frustrating.  If the TS mechanicals are improved over the stock version, they may have solved some of those issues.

That's interesting thanks. I'm not too worried about light leaks, i can always diy a cap for the hole in the back and use it when imaging. However I am worried about holding collimation, that didn't cross my mind. I will do some more research but in any case I'm sure it would still hold collimation and do a better job than my current celestron 8 inch newt in a relatively low price.

[RJF-Astro]

The f/5 version will be a lot easier in this regard. Collimation of f/5 or slower scopes is a lot less demanding. So you lose some speed, but it might be worth it.

[xiando]

IFFF you're interested in high quality mirrors and a bit better packaging/features for a 6" newt than the average GSO 6", you *might have a gander at Orion UK, especially if you're local(ish) to the UK.

[Astrohoven]

IFFF you're interested in high quality mirrors and a bit better packaging/features for a 6" newt than the average GSO 6", you *might have a gander at Orion UK, especially if you're local(ish) to the UK.

oh I'll check Orion. I had the impression that TS and GSO mirrors might be a bit higher quality than Orion's.

[xiando]

oh I'll check Orion. I had the impression that TS and GSO mirrors might be a bit higher quality than Orion's.

to be clear Orion UK, not "Orion" 

 

At least on paper... 

[Astrohoven]

After some more research, I'm getting even more worried about switching to f4. The TS has very thin spider vanes and I'm worried it might not hold collimation even throughout one session; not to mention how sensitive it would be to collimation, spacing and coma. 

 

Any recommendations from experience would be much appreciated.

[calypsob]

The thing I dont like about these is how thin the tubes are and how the mirror cell rests on cork pads. The cell slides around and easily looses collimation. I had to shim and silicone glue my cell into place. Honestly I suggest you look at a 6” f6 and a sharpstar reducing coma corrector. It wont be the fastest setup but the stars will be easy to dial in. Also be sure to pick up a good collimation setup.

[xiando]

After some more research, I'm getting even more worried about switching to f4. The TS has very thin spider vanes and I'm worried it might not hold collimation even throughout one session; not to mention how sensitive it would be to collimation, spacing and coma. 

 

Any recommendations from experience would be much appreciated.

FWIW, my GSO F4 holds collimation over an evening. 

 

The spider is only holding up a small secondary mirror and its carrier.

 

If anything was to worry about, imo,  it'd be the focuser holding a "heavy" optical chain while the optical chain is hanging at a ~90 degree angle to the ground, but again, I haven't had any real issues there either.

 

Still, if I was to do it all over again, and with what I know now, I'd probably want the ability to choose better mirrors and the ability to choose a slightly smaller secondary to reduce the central obstruction at purchase. And a fan might be nice too.

Edited by xiando, 04 June 2020 - 08:27 PM.

[Astrohoven]

I think after all your comments, it's better if I wait till I have a higher budget and get something better. I'm already extremely frustrated with my current f5 newt. so I can't imagine the frustration I'd get if I invest money in a new scope that turns out not to be such an improvement. 

Edited by Astrohoven, 05 June 2020 - 04:31 AM.

[Viktorious]

Sounds like an idea. I haven't tried myself but from what I've gathered in reading, the UNC line by TS-Optics should be good for a 6". The optics is tested and the carbon tube built by the Germans. The ONTC even better but they start at 8".

[Astrohoven]

Sounds like an idea. I haven't tried myself but from what I've gathered in reading, the UNC line by TS-Optics should be good for a 6". The optics is tested and the carbon tube built by the Germans. The ONTC even better but they start at 8".

Exactly what I'm thinking about. I'll wait for a couple of months and get the UNC. the ONTC is way too expensive for me. I've been checking images taken by the UNC and it svery impressive. Time to research its cons now.

[Viktorious]

Time to research its cons now.

Do report back what you find! I'm also thinking about adding the 6" f/4 UNC as a wide field/grab n go in the future. 

[Astrohoven]

Do report back what you find! I'm also thinking about adding the 6" f/4 UNC as a wide field/grab n go in the future. 

will do. i just noticed ur using the GSO f4 newt which is probably close to the Photon series? is it causing you issues?

[Viktorious]

will do. i just noticed ur using the GSO f4 newt which is probably close to the Photon series? is it causing you issues?

It's only a few weeks old and have only had it out twice, so no proper experience with it. But so far I love it, hence why I'm considering the 6" as wide field instead of a refractor as was the plan before.

 

Understandably it arrived with the main mirror slightly out of collimation. Collimating was a breeze though and has been kept since (I check on Polaris every time I set up).

The focuser feels solid so far, but the heaviest load has only been an ES68 24 mm with a phone attached with a Celestron NeXYZ adapter totaling at 820 g.

Only aberration I've noticed so far is coma (a given at f/4). My coma corrector was delayed and will arrive in two weeks.

 

After you wrote about the spider veins I had to double check mine and it does seem like they are 0.8 mm instead of the 0.5 mm the Photon has. They feel solid though and since the big 88 mm secondary was aligned at delivery I'm not complaining! 

Edited by Viktorious, 05 June 2020 - 07:40 AM.

[RJF-Astro]

I have a 6" f/4 UNC on order, so no experience yet. It takes around 2-3 months if you order one. Something to keep in mind when saving up, although you do pay up in front.

[JAS62]

As mentioned, I have the Apertura 6" F/4.  A re-branded GSO.  I collimate it every time before a session.  It never too far off.  The optics are pretty good.  The mirror produces a lot of coma.  A coma corrector is necessary equipment.  It will not make the images perfect, but it helps quite a bit.  The issues with the focuser is valid.  Mine supports a DSLR with the corrector and various extenders.  The friction tensioner in the focuser needs to be messed with to work correctly.  This is something I check when mounting the camera.  If you lock the focuser after focusing there's no issue.  For the price is paid I feel I'm getting a lot out of the scope.  Here's a couple of recent sessions and a shot of my rig:

 

 

 

Clear skies!

Edited by JAS62, 05 June 2020 - 11:18 AM.

[Astrohoven]

I have a 6" f/4 UNC on order, so no experience yet. It takes around 2-3 months if you order one. Something to keep in mind when saving up, although you do pay up in front.

Yes i was i ncontact with Ben from TS. I think it will be worth the wait.

[Astrohoven]

 

As mentioned, I have the Apertura 6" F/4.  A re-branded GSO.  I collimate it every time before a session.  It never too far off.  The optics are pretty good.  The mirror produces a lot of coma.  A coma corrector is necessary equipment.  It will not make the images perfect, but it helps quite a bit.  The issues with the focuser is valid.  Mine supports a DSLR with the corrector and various extenders.  The friction tensioner in the focuser needs to be messed with to work correctly.  This is something I check when mounting the camera.  If you lock the focuser after focusing there's no issue.  For the price is paid I feel I'm getting a lot out of the scope.  Here's a couple of recent sessions and a shot of my rig:

 

 

 

 

 

 

Clear skies!

 

That's too much coma for my taste. Which CC are you using?

[JAS62]

That's too much coma for my taste. Which CC are you using?

I am using the TPO corrector.  Nothing too fancy.  I probably could get more of the coma eliminated if I use a higher end corrector.  Didn't want to pay more for the corrector than I did for the scope.    

 

I am not sure your going to get a low-coma F/4 newt.  At least not at this price point.  But I see the UNC looks to be a higher end unit.  Hopefully it will not need too much correction.

Edited by JAS62, 05 June 2020 - 11:57 AM.

[Viktorious]

Joe those are lovely images!