Orion Q70 2", 32mm, 70 AFOV on 203x1000 - F5 fast reflector.

[N3ptune]

Hello this is an attempt to gather simple relevant information about an economic 2 inches eyepiece to be used on a fast telescope. Some have said to me, there will be coma at the edges, some said the piece is going to do a good job for the price.

So we had an agreement at my local shop to test it, because they too believe the quality/piece is good but they were not sure about the results with a fast F5 scope. I now have it for 10 days to make some tests and decide if I keep it or return it to get something else. (But what?)

This is the piece and this is the telescope.


TEST #1

PROS:
- My first reaction when pointing towards Cignus was "wow" because of the field of view, 70 is great. The eye relief is comfortable also.
- The piece is not too big or heavy like 82 degrees ES, Luminos, etc.
- The price.
- The 32 mm is a great size considering my 25mm, the power gap between the 2 is perfect for me, that hit the spot. 
- The DSO on the center of the piece, great and powerful view.

OBSERVATIONS:
- 32 mm seems close to the maximum usable size on my scope. In my light polluted region, it's obvious that the background it brighter then with the 25mm. But I didn't feel that was a bad thing.
- I was able to find the Dumbell nebula easily, the view was interesting and satisfying.
- Same thing for the Ring nebula.
- For the Hercule Great Cluster, I could see more length in diameter then with any of my others EP (25mm, 18mm, 4.7mm) great view honestly, I was impressed, the piece is powerful to reveal more of the cluster.
- The object which is centered, the piece is paying for itself.

CONS:
- There is coma on really bright stars, it's possible to adjust the focuser on the center part and it's ok.
- To watch a large star field like in Cygnus, the coma is there, if the stars are dim, there is not too much coma.
- It's possible to adjust the middle part of the FOV to improve the coma situation, but then the center is no more perfect.
- The eye cup is quite rigid and I need my 2 hands to retract it. (No big deal)
- The eye cup is useless for me, so it needs to be retracted all the time.
- The first lens is quite recessed. (No big deal but it's not a quality feature to my taste and compare to a ES model.

CONCLUSION:
- I think, right now, this piece is 3.5 stars out of 5 because the star field, especially with bright stars suffers from coma. Because of that the entire 70 degrees is not really usable.

The Coma situation might not be that bad either considering this sketch:

- The Q70 is far superior to my old LET 28mm. I think 28mm is too close to 25mm.
- +-66% of the area is kind of not usable.. i was hoping less coma and blur then that, that's why the piece is 3.5 stars instead of 4 stars out of 5.But 33.5% with no coma on a 32mm also gives a lot to see.



My question right now is: Do I feel it's good enough for me?

--> There is a little fight inside my mind, It's usable, the size is super, the DSO's are beautiful in the center but the bright stars are affected by coma, the star fields are also corrupted, and the 66.4%, is thick and a lot of area... 

On my next test, I want to look at a large open cluster with many bright stars, then, ill be fixed.

[John]

Excellent review - I'm really impressed that you have tried to quantify what you have seen

I suspect the abberation you are seeing is as much astigmatism (which is eyepiece generated) as coma (which is generated by the scope).

There might be some field curvature and / or pincushion distortion contributing to the results as well.

I have tried more expensive eyepieces than the Q70 32 which showed lots of astigmatism if the outer 50% of the field of view when used in my F/6.5 refractor so the Q70 is not doing that badly in an F/5 scope considering it's price.

 

[N3ptune]

Thanks John,

Yes it's a beginner attempt.

Tonight, (if the sky continue to be clear like it is right now) I will try the eyepiece again to study the various effects you talk about, astigmatism from the piece and coma from the scope.. I will try to draw a sketch with the aberration, to get a better idea.

[Louis D]

7 hours ago, John said:

I suspect the abberation you are seeing is as much astigmatism (which is eyepiece generated) as coma (which is generated by the scope).

It's pretty easy to distinguish astigmatism from coma.  Just put a bright star out toward the edge and focus through best focus from near to far and vice-versa and watch the shape of the star change.  If it is sort of line shaped on one side of best focus and line shaped again on the other side, but in the perpendicular direction to the first, it's astigmatism.  Coma always spreads out in a fan shape away from the center regardless of the side of focus.

[N3ptune]

TEST #2.

And I am back from a memorable short 1.5 hour observation, the Milky Way was visible, there was no moon and this one was extremely memorable for me. (;

My goal was to use extensively the new 2 inches Q70 eyepiece and that's exactly what I did, that's the only eyepiece I used. Now I understand why experimented amateurs likes 2 inches wide FOV that much.

6.4 exit pupil is astonishing! it's really great. 

I had to see it to believe it, but now I understand how 6.4 exit pupil use almost the entire 203mm aperture of my telescope. It was like if I had another better telescope capable of seeing much more faint objects, much more stars.

-------------------

My journey took place between Cephus, Lacerta and Cygnus close to the galactic equator, between Alderamin, NGC 7082 and C16 a star field a paradise and exactly what was required to test the 2 inches, with many open clusters, wow!



I have seen so many stars!!!! I just can't believe it and how rich this place was.

TEST:
- First, the instrument took it's time to acclimate with the environment.
- So has my eyes to get a proper dark adaptation.

PROS:
- The focus margin on the Q70 is really large, It took me some time to find the sweet spot. After that was found, the eyepiece came from ok to great! literally. After 15 minutes of observation with proper adjustment, the eyepiece paid for itself entirely with joy. (15 minutes only, it's not a joke)
- I noticed the 66.4% distortion is actually way less then that, not the half of that area but close and the stars in the middle of the FOV were fine, even the bright ones like in M39
- With the 6.4 exit pupil, the telescope was seriously delivering close to the maximum of it's light gathering capacity to my eye. I could see a lot really faint stars, that's the memorable part.

The voyage to that star region was worth more in joy then the price of the eyepiece itself (((:

Considering that, the second test went incredibly well, the piece I gave 3.5 out of 5 yesterday now I feel it's a strong 4 out of 5 (To my personal satisfaction and considering the price) because it's now slightly better then expected. The star fields were more then fine, the DSO's are nice also.

The Q70 can be used on my F5 scope, I will keep the eyepiece.

[Stu]

Nice review N3ptune, I'm glad the Q70 worked out for you

[John]

9 hours ago, Louis D said:

It's pretty easy to distinguish astigmatism from coma.  Just put a bright star out toward the edge and focus through best focus from near to far and vice-versa and watch the shape of the star change.  If it is sort of line shaped on one side of best focus and line shaped again on the other side, but in the perpendicular direction to the first, it's astigmatism.  Coma always spreads out in a fan shape away from the center regardless of the side of focus.

I know but often with lower cost wide angle eyepieces used in a reasonably fast newtonian what you see is often a mixture of the two aberrations, which can make diagonsis more complicated especially if you are new to testing optics.

I've found this guide to aberrations useful over the years - I'm sure you know it

http://umich.edu/~lowbrows/reflections/2007/dscobel.27.html

[Louis D]

9 hours ago, N3ptune said:

The voyage to that star region was worth more in joy then the price of the eyepiece itself (((:

I'm glad you're starting to discover the joy of amateur astronomy.

The sheer joy of cruising the heavens to see what's out there that you haven't discovered yet has become my favorite way to view lately.  For instance, in my AT-72ED at 11x with my 40mm Meade 5000 SWA, it becomes clear that the belt stars of Orion are surrounded by a very nice and large open cluster, Collinder 70.  It is just about impossible to distinguish it from the background sky even at 25x because you're basically looking through it.  Yes, I may be pushing the exit pupil a bit at 6.7mm, but the cluster doesn't stand out as well in my 30mm ES-82 (14x, 5mm e.p.), either, because it is a bit too spread out in that AFOV.  Same goes for my 15x70 binoculars.  It is apparent in my 8x42 binoculars, but not as many stars show up due to the smaller aperture and lower power, so it doesn't have quite the wow factor as it does in the AT-72ED.

Keep up the star cruising and let us know what you discover.

[N3ptune]

Stu
Thanks, I am glad of the outcome because my money was ready to go get the ES 34mm, I already accepted the new spending. But It turns out, there will be no need of a ES, not required right not.

John
Didn't make a sketch with the coma and astigmatism yesterday, because the situation improved, I just enjoyed the scene instead.

From the images in your link (without reading the text) and there is:

Coma: yes
Astigmatism: Definitely yes close to the edge.
Distortion: I didn't watch any large body to see about that
Field curvature: I can't tell yet.
Lateral color: no

But the color of the stars is different from my Xcel LX eyepieces. I prefer the color from the celestrons, they are more vivid, the yellow is stronger, blue is stronger. On the Q70, the white and blue stars appear to have a light hue of green?!

The green coating could do that maybe?

Louis D

I was not aware of the collinder 70 large open cluster, I knew the belt is a really interesting place, I can't wait to look at it again with my 32mm (: We need to wait for it to return.

The discovery of the joy is non stop, an infinite free spectacle. It will last my entire lifetime.

[N3ptune]

2017-09-24 - Update 13 months later.

The Q70 gave me great services for many months with it's wide field views. I inserted it inside the focuser at least 150 times (more) to look at many things (minimum) and paid 139CAD total for it, It paid for itself many time.  I had great views of the Veil nebula using a narrow passband filter has well has the North America Nebula, but I decided to sell it last week, it was replaced with a ES 34mm 68d grenade

At the end of the day, I could not live anymore with the aberration it has, especially the astigmatism (has I was warned from the beginning)  The outer part and middle part of the FOV could not reach the focus at the same time, this became a serious annoyance over time.

Can I still say it's a good eyepiece today? for large nebulae with a filter it's good, but to look at dense star fields, with a bit more experience, It's not cutting it, It can't even be compared with the ES 34mm in term of quality and correction.

This was still a great journey with the Q70 involving strong memories too.

 

[Louis D]

On 9/24/2017 at 14:01, N3ptune said:

2017-09-24 - Update 13 months later.

The Q70 gave me great services for many months with it's wide field views. I inserted it inside the focuser at least 150 times (more) to look at many things (minimum) and paid 139CAD total for it, It paid for itself many time.  I had great views of the Veil nebula using a narrow passband filter has well has the North America Nebula, but I decided to sell it last week, it was replaced with a ES 34mm 68d grenade

At the end of the day, I could not live anymore with the aberration it has, especially the astigmatism (has I was warned from the beginning)  The outer part and middle part of the FOV could not reach the focus at the same time, this became a serious annoyance over time.

Can I still say it's a good eyepiece today? for large nebulae with a filter it's good, but to look at dense star fields, with a bit more experience, It's not cutting it, It can't even be compared with the ES 34mm in term of quality and correction.

This was still a great journey with the Q70 involving strong memories too.

 

Ah, the financial woes associated with advancing observing skills.  After a while longer, you'll realize you're seeing coma from the scope in the outer field and you'll want it gone as well.  Another hit to the wallet.

[N3ptune]

13 hours ago, Louis D said:

Ah, the financial woes associated with advancing observing skills.  After a while longer, you'll realize you're seeing coma from the scope in the outer field and you'll want it gone as well.  Another hit to the wallet.

heheh that's possible, the Coma is still there with the ES, it could be better with a coma corrector eventually.

[Dave In Vermont]

If you find a really good coma-corrector out there at a really good price-point - please do let me know? You know where I'll likely be...

Coma is often a cause of consternation - especially as we get more experience in observing the stars. I have the same eyepiece for got from Orion-USA, but from a different outfit and branded as 'SWA'- this being for 'Super-Wide-Angle.' I like them and have used them in my ST80 and Maksutov - which is F/12. Oddly enough, these work better for me than in the F/5 ST80 than the F/12 Maksutov. It's about as low-magnification as these Maksutov-Cassegrains can handle without becomming a giant kidney-bean visually. But certainly worth the low-price.

Until Later,

Dave

[N3ptune]

Hello Dave,

I never saw any good deal on a coma corrector yet... I'll wait for the breaking point with my current eyepiece before I start thinking about buying a coma corrector seriously. I resolved the astigmatism problem, this should buy me some time, a few months at least. (A few years would be great)

A few years before buying the next thing! (;

But the ST80 should not induce any coma, I think.

 

 

[Louis D]

I ended up buying a used OPT (GSO) CC for about $75.  I then had to invest another $25 in a 15mm or 20mm spacer ring (I can't remember which) to get the spacing correct for most of my eyepieces and some rubber O-rings to parfocalize a few of my outlier eyepieces.  Luckily, most of my collection either focuses at the shoulder or within 5mm of it, which is within the correction margin for this CC.  The edges still aren't perfect, but now I have to really go looking for it instead of it distracting me from the on-axis view.  All told, I'd say the $100 was worth it when using wide field eyepieces.  It also comes in handy to allow for prime focus photography with a DSLR on my Dob.  Otherwise, I need to use a barlow to reach focus.

[N3ptune]

11 hours ago, Louis D said:

I ended up buying a used OPT (GSO) CC for about $75.  I then had to invest another $25 in a 15mm or 20mm spacer ring (I can't remember which) to get the spacing correct for most of my eyepieces and some rubber O-rings to parfocalize a few of my outlier eyepieces.  Luckily, most of my collection either focuses at the shoulder or within 5mm of it, which is within the correction margin for this CC.  The edges still aren't perfect, but now I have to really go looking for it instead of it distracting me from the on-axis view.  All told, I'd say the $100 was worth it when using wide field eyepieces.  It also comes in handy to allow for prime focus photography with a DSLR on my Dob.  Otherwise, I need to use a barlow to reach focus.

Wow it,s really inexpensive but they say it's good F4 and slower, my telescope is F5. I wonder how it can be, the Skywatcher coma corrector will cost around 450CAD  same thing with the Baader version.  The difference is huge.

[Louis D]

2 hours ago, N3ptune said:

Wow it,s really inexpensive but they say it's good F4 and slower, my telescope is F5. I wonder how it can be, the Skywatcher coma corrector will cost around 450CAD  same thing with the Baader version.  The difference is huge.

Perhaps they are low volume items or use special glass types or are designed to mate especially well with that OTA or give exceptional photographic results.  The human eye is a lot more forgiving than imaging sensors.

[N3ptune]

Ill wait for the need to raise first, to a point where i can't tolerate any coma no more.  At least I know the OTA exists, which is good.

[Dave In Vermont]

Well as far am I'm concerned - the proverbial jury is still out until someone (or 'ones') conducts a side-by-side test on these. I'll be most interested to hear the results.

Dave