Anyone use TeleVue Dioptrx?

[Alan White]

I find I am seeing odd thing on low power EP with my 10" dob, thought my mirror was out, but it's fine.
Compared views against another identical Dob and swapped EP with the other observer and the same 
anomaly shows at low powers, I think I am seeing some coma but it is f4.8, so surprised that I do.

I wear glasses for driving and star spotting, I am a low tech star hopper with a Telrad,
But cannot get on wearing them to observe.

Having had a good read all over the net, I think I am seeing my own astigmatism, which my glasses of course correct.
Its not massive but would require a 1.00 Dioptrx.
Would this be a worthwhile addition for me, it will require a few EP changes, but I am happy to do this.
Because is its more Astigmatism than Coma I am seeing then Dioptrx is a far cheaper alternative to a TV Paracorr.



 

[Scooot]

I use a dioptrx Alan, mines 1.25. I can get away using my 10mm Delos without using it or glasses but it’s necessary on all my others to sharpen up the view. I use both the dioptrx and a paracorr on, as you know, the same scope, and I’d notice the difference without the paracorr, particularly with the 17.3mm eyepiece and above. Dioptrx is cheaper so maybe try one before buying the paracorr, at least you’d be able tell if you think you’d need the paracorr or not.

Edited October 2, 2019 by Scooot

[Paz]

I use a 1.00 Dioptrx for my left eye and I find it makes a big difference especially at larger exit pupils. Under 2mm for me the benefit starts to fade and under 1mm it's hard to detect.

The plus side is that it does work and stars are pin sharp everywhere.

The downside is that it is a bit of hassle swapping it between eyepieces and it is also a bit of a workload keeping it aligned. When it is aligned things snap into sharpness, but it doesn't have to be out by much to become no use. You can't see or feel anything on it to align it in the dark. You have to either light it up to see the alignment and lose some night vision or align it by looking through it. If you are looking at a bright enough star you can do the latter, but if not it is tough.

Unless you are using am alt az set up with a permanently upright eyepiece that keeps your head upright all the time, your attitude to the eyepiece will be a constantly rotating/changing requiring you to realign the Dioptrx.

I often prefer to use my glasses with good quality long eye relief eyepieces because it is less of a workload, but when I have time for longer sessions the Dioptrx is used as the views are simply better.

I took mine on holiday with a 50mm monocular (5mm exit pupil) and it made a big difference to the views, but it was a bit of grief having to hold it in by hand as I couldn't make a contraption to hold it on.

[Alan White]

12 hours ago, Scooot said:

I use a dioptrx Alan, mines 1.25. I can get away using my 10mm Delos without using it or glasses but it’s necessary on all my others to sharpen up the view. I use both the dioptrx and a paracorr on, as you know, the same scope, and I’d notice the difference without the paracorr, particularly with the 17.3mm eyepiece and above. Dioptrx is cheaper so maybe try one before buying the paracorr, at least you’d be able tell if you think you’d need the paracorr or not.

A question please Richard.
When using the 10" seated, does the dioptrx have to be rotated as you move the scope to keep the correction working for you?

[Alan White]

11 hours ago, Paz said:

Unless you are using am alt az set up with a permanently upright eyepiece that keeps your head upright all the time, your attitude to the eyepiece will be a constantly rotating/changing requiring you to realign the Dioptrx.

I will only be using alt az mounted scopes, mainly the 10" OOUK Dob.
Do you find it a nuisance at your 14" Dob at all?

[Carbon Brush]

I considered (a long time back) an eyepiece/adapter that deals with astigmatism. But never bought one.
To me having to keep the EP aligned to your eye may be a bit of bother when the scope moves around the sky.
Then what if (like me) you have different astig in left/right eyes and you swap eyes while viewing?

The solution I opted for was contact lenses.
They sort the differing astigmatism in both eyes and can be used away from the scope.
They are for distance & astig correction, which means cheap reading specs for small fiddly things around the scope.

Following the thread with interest.

David.

 

[Alan White]

2 hours ago, Carbon Brush said:

I considered (a long time back) an eyepiece/adapter that deals with astigmatism. But never bought one.
To me having to keep the EP aligned to your eye may be a bit of bother when the scope moves around the sky.
Then what if (like me) you have different astig in left/right eyes and you swap eyes while viewing?

The solution I opted for was contact lenses.
They sort the differing astigmatism in both eyes and can be used away from the scope.
They are for distance & astig correction, which means cheap reading specs for small fiddly things around the scope.

Following the thread with interest.

David.

 

Now that's a thought.

[djpaul]

I use a televue dioptrx 1.25 on my eyepieces that have an exit pupil of 1.7mm and higher.

Namely my 17mm ethos and 26mm nagler.

I did borrow a 1.50 dioptrx off Kerry from this site ( which reminds me I still need to give it back ) 

I went to my optician and was told I needed 1.25.

I bought one and was so impressed I bought another so I don't have to swap them from eyepiece to eyepiece. 

You have to find the sweet spot when using a dioptrx .but it just takes some getting used to.

I also have a televue 32mm plossl but I use it with glasses on as the eye relief is big enough to get the whole fov in.

[djpaul]

On another note.

If you are considering contact lenses beware of the dangers.

Speak to your optician about the complications of them.

Contacts almost cost me my eyesight a few years ago.

[Paz]

4 hours ago, Alan White said:

I will only be using alt az mounted scopes, mainly the 10" OOUK Dob.
Do you find it a nuisance at your 14" Dob at all?

It does require adjusting but it is slightly less of an issue with the dobsonian as the eyepiece angle doesn't change around as much as it does with scopes that use diagonals. With diagonals I usually rotate the eyepiece to point sideways so that my head/eyes are pointing forwards as naturally as possible and this makes for huge changes in the orientation of my eye to the eyepiece.

p.s. It also swings the orientation of the view all over the place, causing me on many occasions to get confused and  lost when star hopping if I don't have a raci finder!

[Scooot]

13 hours ago, Alan White said:

A question please Richard.
When using the 10" seated, does the dioptrx have to be rotated as you move the scope to keep the correction working for you?

No not really Alan. Once I’ve set it I don’t usually need to alter it, but if I do it’s only a tweak. The dioptrx ring is labelled A to F and I now know where to set it, or roughly so I get it in the correct position quite quickly.
The most annoying thing about it for me is if I’m using a shorter eye relief eyepiece, such as my 13mm ethos I have to have the eye guard down. This means my eye is closer to the lens and in certain circumstances the heat from my eye causes it to mist up. This is where the Delos are a significant advantage because I can use the dioptrx with the eye guard up. 

I can read without my glasses on so using the dioptrx means I can also use the scope without them. Otherwise I’d have to wear glasses to use the scope and keep taking them off to read.

I also have contact lenses but I don’t wear them much & I don’t like wearing them for astronomy. Their prescription isn’t as precise as my specs and they have a habit of spinning in my eye. This alters the astigmatism correction so I have to wait until they settle again.

Edited October 3, 2019 by Scooot

[Louis D]

I have two diopters of cylinder (astigmatism) correction in my observing eye.  I also have presbyopia, so I normally wear bifocals.  The problem is that bifocals prevent viewing the entire field of wide angle eyepieces without a line through it and all at the same focus point.  My solution has been to only buy eyepieces with long enough eye relief to use while wearing eyeglasses.  In addition, I bought a pair of single vision, distance-only eyeglasses with low index plastic lenses to reduce edge chromatism and to show the entire field in focus at once.  Also, they're cheap enough I don't worry about scratching them on eyepieces if I push in too hard on an eyepiece with an exposed metal edge like the 27mm Panoptic while trying to take in the entire field.  They are always perfectly aligned for optimal astigmatism correction because they're attached to my head, not the eyepiece like a Dioptrx.  I can also instantly go from looking at the sky to the eyepiece without having to deal with taking my glasses off.  Being a devoted star hopper, this is very important to me.  As for reading charts, I can always look under my glasses and deal with my astigmatism since my eyes are fixed focus at about 10 inches which is perfect for reading.

Edited October 4, 2019 by Louis D

[Carbon Brush]

On 03/10/2019 at 13:17, djpaul said:

On another note.

If you are considering contact lenses beware of the dangers.

Speak to your optician about the complications of them.

Contacts almost cost me my eyesight a few years ago.

Slightly away from topic.

In the UK contact lenses can only be prescribed by an optician are subject to on going checks. I have always (15 years) found the prescribing opticians to be very good at explaining risks, and warning signs to prevent serious problems.

HTH David

[Alan White]

Having been to my Optician, who is an old friend as well.
I can report back that I am now a broken person, the cost of 2 new pairs of varifocals,
even at mates rates is rather a lot! 
No contacts here.
I have also ordered the correct Dioptrx unit via @FLO earlier today.
I will report back on how I get on.

[djpaul]

Great to hear.

Looking forward to your report 

[Alan White]

Now in post from FLO 😊

[Alan White]

I can report it arrived a few days ago, tonight was first clear (ha ha) evening, 
well the transparency was poor and it was very damp in the atmosphere, but needs must.

I used the OOUK OD150 f5 for a test run and popped in the 27mm Panoptic with the Dioptrx.
Well what can I say, that coma was my Astigmatism at low power, all very much nicer to view and
fainter stars are now visible 

I had a look about, did some general sky surfing, Double cluster was great as were many targets, 
I like the Dioptrx, but the 27mm gives me a balance challenge in the short scope, Hmmm, always something else.

Dioptrx works great, was not needed at 9mm but conditions were mixed so not a full test.
Was it worth it, you bet it was.

[djpaul]

1 hour ago, Alan White said:

I can report it arrived a few days ago, tonight was first clear (ha ha) evening, 
well the transparency was poor and it was very damp in the atmosphere, but needs must.

I used the OOUK OD150 f5 for a test run and popped in the 27mm Panoptic with the Dioptrx.
Well what can I say, that coma was my Astigmatism at low power, all very much nicer to view and
fainter stars are now visible 

I had a look about, did some general sky surfing, Double cluster was great as were many targets, 
I like the Dioptrx, but the 27mm gives me a balance challenge in the short scope, Hmmm, always something else.

Dioptrx works great, was not needed at 9mm but conditions were mixed so not a full test.
Was it worth it, you bet it was.

You managed to turn it to fit your astigmatism with no issues then.

Well done.😁

[Alan White]

8 hours ago, djpaul said:

You managed to turn it to fit your astigmatism with no issues then.

Well done.😁

Oh yes, took a bit of fiddling about, but once I found the spot, wowzer.

[Louis D]

Would you be willing to compare the view through single vision eyeglasses versus the Dioptrx sometime?  I found the biggest problem with eyeglasses was that older pairs have microscratches all over them, so I bought a brand new dedicated astronomy pair to remedy that.  As stars passed over those microscratches, they would suddenly have diffraction spikes, ruining all that work to perfect the eyepiece image with correctors, collimation, and premium eyepieces.

[Alan White]

Sorry Louis but all my glasses are now varifocal, not a single vision pair left.
 

[djpaul]

My problem with wearing glasses is not getting much of the fov with my ethos and nagler eyepieces. 

So for that reason the dioptrx is perfect.

However I can see the whole fov wearing glasses with my 32mm and 25mm televue plossls.

[Louis D]

21 minutes ago, djpaul said:

My problem with wearing glasses is not getting much of the fov with my ethos and nagler eyepieces. 

So for that reason the dioptrx is perfect.

However I can see the whole fov wearing glasses with my 32mm and 25mm televue plossls.

The only eyepieces I have that issue with are my ES-92s.  The left and right edges are fine, but the top and bottom fall outside the corrected area.  However, it's pretty rare that I look up or down rather than left or right.

I can't use the Ethos or non-T4 Naglers with glasses because the eye relief is too short.  It's my understanding that you still need about 15mm of usable eye relief to use the Dioptrx successfully; so, for example, the 16mm Nagler T5 wouldn't be compatible with them.  My other thought is that my long eyelashes would probably grease up the Dioptrx corrector lens on shorter eye relief eyepieces whenever I blink.

[Louis D]

1 hour ago, Alan White said:

Sorry Louis but all my glasses are now varifocal, not a single vision pair left.
 

I bought my single vision distance glasses from EyeBuyDirect after finding a frame of about the same dimensions and style as one I liked from the optometrist's store.  I think I paid under $20 for them, and they are of a surprisingly good quality.  The frame is actually much nicer than my wife's Ray-Ban frames.  You seem to pay for the name in the case of Ray-Ban.  They stay in a case in my astro toolbox along with my miscellaneous astro gear.

Edited October 23, 2019 by Louis D