power mate or no

[poider]

G'day all, I now have the skywatcher ED100 evostar doublet.
The highest useful magnification is X200.
I could achieve this with a single 4.5mm eyepiece or a 9mm eyepiece with a 2x powermate, or an 18mm eyepiece with a 4 times powermate.
Apart from the convenience of having the power mate for other eyepieces, is there a combination that would be better than the rest?
I tend to think that the less glass the better so my logic says the 4mm would be the clearest option, More for observing but maybe some astro photography as well, I have had some success with the 900mm focal length (1350mm) with the 1.5 crop sensor Nikon D7200 photographing the orion nebula https://flic.kr/p/2hMRmL5
What you recommend.
Peter

[Outcast]

Hi Peter,

I have a 2.5x powermate which I used to use a lot with my first refractor when I only had a few eyepieces.

I used it a large number of times with a Meade 6.7mm UWA EP on my 80mm triplet to view Saturn & for some lunar viewing at high magnification.

Whilst subject to viewing conditions, I found the views in general to be quite exquisite. It allowed me to push my 80mm pretty hard magnification wise with what eyepieces I owned at the time.

I've subsequently used a 2x barlow, not even close viewing quality wise...

These days, and a number of years (& credit card bills) later, I have a largish collection of eyepieces so, I tend not to use it so much.

I am however planning to use it in my imaging train, particularly for planetary imaging.. haven't done so yet so can't comment directly on how good or bad it will be but, from what I have read, it should do a damn good job...

So, if you are looking to minimise expenditure on eyepieces, I would say go for it.. if you're looking for it's usefulness in AP, from what I have read, I'd again so go for it...

Keep an eye out in the classifieds, they come up every so often, (2x, 2.5x, 4x & 5x powermates) at pretty reasonable prices. Just be aware, the 2.5 & 5x are 1.25" only.

Cheers

[Startrek]

Peter
I’ve used the full set of TV Powermates for about 3 years now both in visual astronomy and Planetary imaging
They compliment my TV eye pieces and perform extremely well in my 12” Goto dob for lunar and planetary observing
For planetary imaging I use mostly the 4 x and 5 x in my 6” and 8” newts with TV T ring adapters and my DSLR
For Lunar imaging in the 6” and 8” I use the complete set
I have used 2x and 2.5x Barlow’s for visual but the Powermates are so much better in terms of

[Merlin66]

Are we talking visual or photography???
For solar imaging 99% of the time On the ED80 use the x2.5 PM or the Baader x2.25 Hyperion Barlow. The Meade/ ES x3 telecentric also works well.

(I just wish they made a x3.5 version of the PM or telecentric)

For visual, although I have many (!!!!) Barlow’s and PM’s I seldom use them.
A good Plossl or ortho will work well for the higher magnifications.
I have an ol’ 4.8mm Nagler which is very good, but not used as much as my 6mm Monocentric.

Just my 2c.

[Wilso]

Hi,
I found the 3 element shorty type Barlow to be the best one I’ve tried so far, not quite parfocal with the eyepiece . (For visual)
Ken try using a 1” extension between the powermate or extender to get closer to the magnification your after.

[Merlin66]

Darren,
Varying the back focus distance doesn’t change the magnification when using a telecentric design.
Sure it works for a Barlow......

[Wilso]

My mistake Ken your 100% correct, I should have remembered that from when I bought my extender :thumbsup:
“ the negative doublet is followed by a positive doublet that turns the exiting rays back to parallel - ie, telecentric. Because the rays are parallel, the distance between the EP and the amplifier elements is [broadly] irrelevant as the image amplification was done internally, between the TA lens elements.”

[poider]

https://flic.kr/p/2hMRmL5
With the ED100 evostar and the Skywatcher star adventurer and the Nikon D7200