Short Focal Length Plossls?

[Guest]

The 4.5 inch reflector that I use came with some cheaper MA EP. I recently got a 15mm Plossl for it.  Would upgrading the 9mm MA to a similar sized Plossl be of any benefit?  It also came with a cheap 2X Barlow, I guess updating that for something better would certainly help?

[Alan64]

A 9mm Plossl should be allright.  Anything below that will have a tiny eye-lens and tight eye-relief.

I have a Vixen NPL 6mm Plossl.  I have to hold my eyeball right up to the lens, to where it almost touches same, and in order to see the full field-of-view.  It can be uncomfortable to use, but the views are outstanding...

It's a keeper and a half.

[Alan64]

Which telescope do you have exactly, the make and model?  I have a 4.5" Newtonian myself, a Meade.

[John]

Using a barlow lens with a medium focal length plossl actually improves the eye relief a bit so is worth considering as an alternative to short focal lengths in that design.

 

[Guest]

1 hour ago, Alan64 said:

Which telescope do you have exactly, the make and model?  I have a 4.5" Newtonian myself, a Meade.

It's a Meade Newtonian too.  A 20 year old 114-900 EQ-1B.

[Guest]

56 minutes ago, John said:

Using a barlow lens with a medium focal length plossl actually improves the eye relief a bit so is worth considering as an alternative to short focal lengths in that design.

 

I've got a Meade 4000 15mm Plossl. Would a decent 2X Barlow improve things?  The OEM one is plastic!

Edited February 13, 2020 by Guest

[joe aguiar]

Now I norm dont want to use anything less then a 10 (9 is close) with ep that have small lens or eye relief 

There are good ep like the radian that are not too expensive if u find used ones,that you can use a 3 4 or 5mm and it has large lens and eye field.

But if u only want plossls or super plossls then a with Barlow may get the high power that want.

 

joejaguar 

 

Edited February 14, 2020 by joe aguiar

[Alan64]

13 hours ago, merlin100 said:

I've got a Meade 4000 15mm Plossl. Would a decent 2X Barlow improve things?  The OEM one is plastic!

Yes, I have the same 114/900...

Let's take the 900mm focal-length of our telescopes and see what we get.  The planets become interesting at 150x and up, up close...

900mm ÷ 150x = a 6mm eyepiece.  The telescope is certainly capable of reaching even higher powers, up to 200x, and beyond even whilst observing the Moon's craters, and within those, the craterlets; not to metion the walls of the craters as they slope upward.

You can get a 2x-barlow, and combine that with a 12mm eyepiece, and for a simulated 6mm.  A 9mm can be combined with the barlow, and for a simulated 4.5mm(200x).

In order to aid in the hunt, a 32mm Plossl is also recommended, and for your lowest power and widest view of the sky.  Once you spot something or other, you simply pop in the shorter eyepieces and get closer and closer still.

 

[John]

14 hours ago, merlin100 said:

... Would a decent 2X Barlow improve things?  The OEM one is plastic!

Yes. The image you see is only as good as the weakest element in the optical train.