Author Topic: new TV Delite 3mm  (Read 105 times)

Tyson Conway

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new TV Delite 3mm
« on: December 29, 2017, 02:13:56 PM »
The new TeleVu Delite 3mm is very tempting. However, I am concerned how it will behave with my Orion 6inch F/5 150mm Newtonian. I worry that the Delite with its 62 degree FOV will exhibit too much coma in my Orion. Would appreciate any comments.



Sean Lee

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Re: new TV Delite 3mm
« Reply #1 on: December 30, 2017, 11:50:21 PM »
With the shorter F/L and modest 62° It may surprise. IME the smaller the FOV (0.25° in this case) the less Coma (from the mirror) is seen.

Mike

Deandre Fulce

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Re: new TV Delite 3mm
« Reply #2 on: January 03, 2018, 03:17:34 PM »
Ditto what Mike said about coma. My concern with any 3mm eyepiece is that my seeing conditions would allow 250x only rarely. I don’t know what else you have in the way of eyepiece focal lengths, but a longer fl Delite might see more use.

Matt Marquez

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Re: new TV Delite 3mm
« Reply #3 on: January 04, 2018, 12:02:25 AM »
Coma should be the least of the problems that focal length might present. If your observing conditions allow those magnitudes then the ep should work great.

ocgisfulctel

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Re: new TV Delite 3mm
« Reply #4 on: January 09, 2018, 11:52:57 PM »
What?

clicpostreta

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Re: new TV Delite 3mm
« Reply #5 on: January 10, 2018, 10:43:00 AM »
Quote
What?

A 3mm eyepiece will yield 250X which is quite a bit for a 6" Telescope. Not unheard of, but not that common either.
What are you main targets?

Mike

trafefupgi

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Re: new TV Delite 3mm
« Reply #6 on: January 26, 2018, 08:36:59 AM »
That 3mm Delite would be one of my most eyepieces in my seeing. Coma won't be much of a problem at that high power. A perfect 6" mirror should do 400x easy.

monsresiwor

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Re: new TV Delite 3mm
« Reply #7 on: January 31, 2018, 02:01:18 AM »
Quote
That 3mm Delite would be one of my most eyepieces in my seeing. Coma won't be much of a problem at that high power. A perfect 6" mirror should do 400x easy.

I doubt that any 6" obstructed scope will go to 400x on a regular basis.
Yes one can get the magnification but I doubt there will be any benefit to the image quality or detail, a highly magnified mushy image would be the likely result.
A 3mm in the OPs scope will give an exit pupil of 0.6mm at 250x and a TF of 0.248º.
At that power seeing will be more of an issue than coma.

prehconbubun

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Re: new TV Delite 3mm
« Reply #8 on: February 02, 2018, 05:58:12 PM »
Quote
Quote

That 3mm Delite would be one of my most eyepieces in my seeing. Coma won't be much of a problem at that high power. A perfect 6" mirror should do 400x easy.

I doubt that any 6" obstructed scope will go to 400x on a regular basis.
Yes one can get the magnification but I doubt there will be any benefit to the image quality or detail, a highly magnified mushy image would be the likely result.
A 3mm in the OPs scope will give an exit pupil of 0.6mm at 250x and a TF of 0.248º.
At that power seeing will be more of an issue than coma.
I do very well at crazy powers and use the max powers 80% of the time on all my scopes on my best nites. For my eyes i can't see detail on jupiter at 250x and below and need a golfball size image. I use 500x plenty with my perfect 8" F/8.5 Cave mirror on the moon and jupiter. And where i live i have the seeing that allows powers over a 1000x in my bigger scopes. For deepsky then 200x and below is best. I only view jupiter and moon and no deepsky. For the OP if he has a super good mirror than a 3mm eyepiece will come in handy for PN nebs and M13 or other brighter globs.

Joe Wellard

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Re: new TV Delite 3mm
« Reply #9 on: February 03, 2018, 07:24:41 AM »
Quote
Quote

Quote

That 3mm Delite would be one of my most eyepieces in my seeing. Coma won't be much of a problem at that high power. A perfect 6" mirror should do 400x easy.

I doubt that any 6" obstructed scope will go to 400x on a regular basis.
Yes one can get the magnification but I doubt there will be any benefit to the image quality or detail, a highly magnified mushy image would be the likely result.
A 3mm in the OPs scope will give an exit pupil of 0.6mm at 250x and a TF of 0.248º.
At that power seeing will be more of an issue than coma.
I do very well at crazy powers and use the max powers 80% of the time on all my scopes on my best nites. For my eyes i can't see detail on jupiter at 250x and below and need a golfball size image. I use 500x plenty with my perfect 8" F/8.5 Cave mirror on the moon and jupiter. And where i live i have the seeing that allows powers over a 1000x in my bigger scopes. For deepsky then 200x and below is best. I only view jupiter and moon and no deepsky. For the OP if he has a super good mirror than a 3mm eyepiece will come in handy for PN nebs and M13 or other brighter globs.
I think that you are the exception to the general experience of the viewing public; and hence should be careful with giving advice based on that experience. Maybe add a caveat to set the picture.

I would give my left whosawhatsit to have your steady seeing! (I average 1.9" here)

Jacob Cota

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Re: new TV Delite 3mm
« Reply #10 on: February 09, 2018, 12:04:46 AM »
I owned a 6" scope for a decade and found 40x, 80x, 120x my most used magnifications.
Targets required those magnifications because of size and magnitude.
On planets, 200x was just about the maximum usable for a variety of reasons--seeing, cooling, optical quality.
On double stars, I did occasionally use a 3.8mm eyepiece (about the shortest I could find back then).
That was only 197x in the 6" f/5.
I think that, had it been available then, I could have used the 3-6mm zoom in that scope.
The 3mm wouldn't have been used much.
I did occasionally sneak a barlow into the mix but I found I didn't see anything at 300-400x that I couldn't also see at 200x.

Just a note on calculation: to see the image of Jupiter as large as a golfball held at arm's length will require >300x
The golfball subtends about 4° at that distance = 14,400". If Jupiter is 40", that's 360x.
I think that's about right.
Of course, I also think Jupiter doesn't have to appear that large to see tremendous detail on the planet.
See how far away a golf ball has to be before you can't see its dimples. It's a lot more than 2 arms lengths.

Stanley Elliott

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Re: new TV Delite 3mm
« Reply #11 on: February 09, 2018, 12:55:19 AM »
I think Chas is talking cueball size at 1000x in his larger scopes, and if I tried 1000x in my scope I would see as much detail on Jupiter as I can see on a cueball.

Eric