More EP's or a Powermate for high power range..?

[Fozzie]

morning all,

I've had musings recently that I've a gap in my EP collection in the 5mm to 11mm range (excluding the 8mm plossl) mainly for the following reasons..

My main observing tool recently is the F11 1120mm frac.

My 4.7mm ES82 gives nearly 240x which is useable, but not too often, or sharp enough for my 100% enjoyment.

The next step up is my 8mm TV plossl, I don't mind using this with the eye relief but it's it too tight for everyone else who's attempted to look through it.. This gives me 140x

My next EP is the 9mm xcel lx.. Which is nice but it has quality issues with internal debris from the lens tube darkening getting in the way.. Spoiling the view somewhat.

So I've been thinking about adding in the 6-9mm range, adding a bit more comfort to the view... I have been thinking about the vixen slv or wo spl but again these just jump from 6mm to 9mm and above, no 7mm or 8mm...

Then I thought about a powermate with my existing range... Which would be 11,15,20mm TV plossls and es82 11, 14 & 18mm .. All of these halved with a 2" 2x Powermate would cover everything I'd need..

So the question is based on the vixen slv price.. Two or maybe 3 EP's that could be £200 - £250 or a power mater to give me a range..

Oh I do have a revelation 2.5 Barlow but I've never really got on with it to be honest, find the image too dark and the movement of the eye relief at the lower power end can cause me some issues... This is why I'm checking on the Powermate as ive never used one so would like to know what people think..

Thanks in advance!

Fozzie

[swamp thing]

Hi fozzie

The "darkening" you speak of us due to the extra magnification, not the barlow lens. As we increase mag the exit pupil shrinks and less light is allowed through. This darkening happens with or without barlow lenses, it is unavoidable.

Good Barlows add nothing but power, the extra lenses make such a minute difference that to the human eye its imperceivable.

I use the 2" x2 Powermate and it's quite simply superb. However it is heavy. If you only intend Barlowing 1.25" eyepieces I would get the 1.25" Powermate.....it's cheaper too As only your 18mm is 2" it does seem a bit if a waste getting the 2" version. You could be adding balance issues too with the big 2" beastie.

[alan potts]

It is really a personal thing, myself I only used the Powermate to make stacks of glass that I needed to use in the neighbours garden to use. I really only ever used it with the 8mm Ethos and very good it was to. So I would say add eyepieces but that is coming from the mouth of someone that has too many. The Powermates are superb pieces of equipment and are a great addition to anyone's eyepiece case.

You must consider the points that Swamp Thing has made about balance it is not the sort of thing that would float away in a breeze.

Alan

[estwing]

Best thing in my EP case..

[Fozzie]

Thanks for the thoughts Steve, Alan, yeah I'd assumed the 2" was a chunk of weight, the thought of this over the 1.25" was more future proofing than anything but your right in respect even if I do get a couple of other 2" eps there probably going to be 24-30mm so I fear the it would be redundant in those as I've some nice EP's lower down the order already.

Obviously I've used the Barlow I have with my other EP's and for example of the darkening I mentioned... Last time I compared the 20mm TVP and 9mm excel lx I found the 9mm brighter at a slightly higher mag... Almost as if the use of a Barlow lost some of the through light.. I wonder if this is due to exit pupil size or eye relief?

Hence why the question I'd rather a bright image than a subdued one.. But I'd read that the Powermate is unnoticeable in use..

[swamp thing]

It is certainly unnoticeable in use, of that there's little doubt.

One of the reasons I Powermate is because of the prohibitive cost of owning an extensive Nagler collection. I simply cannot afford a range of premium glass. The Powermate allows one to extend ones eyepiece collection at a relatively cheaper rate.

I've also found that by using wide field eyepieces one simply doesn't need so many eyepieces either. I use one or two eyepieces and the Powermate in my 10" scope, that's all. In my 20" I only use three plus the Powermate.

You may find that the addition of a Powermate frees you up to sell many eyepieces. This is always a benefit.

I belive Cal (estwing) uses only two eyepieces and a Powermate in his 18" Dob. 13 & 21mm Ethoi and TBH you really don't need much more (maybe an 8mm Eh Cal )

This is of coarse how we do it. Alan and others are different, neither is right or wrong. Try a Powermate you may find you love it.....or you may prefer individual eyepieces both is fun

[estwing]

It was Shane who built my telescope that advised me to just try the 21E 13E + powermate combo = Joy!....314x on m13 is superb...perhaps an 8E but really 2 ep's is all that's needed,for me.

[GavStar]

Yes I agree that it's personal preference. I prefer having eyepieces of the right mm rather than using barlows so that theres not too much stuff coming out of the diagonal.

Gavin

[Fozzie]

I've made a decision I'm going to give the powermate a go....

[Pete Presland]

the Powermate is fantastic piece of equipment visual and imaging, mine gets used virtually everytime i am outside, day or night!

[Moonshane]

One issue for me and the reason I sold mine was how far it sticks out. It bugged me and I smacked my head on it a good few times. Not good for me or the focuser.

[Fozzie]

Mmmmmm go on, I'm not adverse to changing my mind...!?

[Dude_with_the_tube]

for your frac,and as your aim is high powers,what means only 1.25" Ep`s will be used,i would go for a Televue 1.25"  2x barlow. Its small,optically perfect and will suit your needs in all aspects. And will cost you only 60 -80 quid.

your mentioned "darkening" happens because its just too much power used.Other alternative is to pick up a bunch or orthoscopics if you are happy to sacrifice FOV and you have no issues with relatively tight eye reliefs.I would not go down the 2" powermate route as that is just one big lump sticking out of focuser and you really dont use 2" eps on it anyway.

[NickK]

I have the TV 2x 2" and 5x 1.25" powermates - both have their uses in the right situation. I've even stacked both together to give 10x.. and at 6700mm fl (f/64) even the sun with white light gets so dim it's difficult to see the detail. At this level of power - the earths atmosphere really starts being turbulent. Running at f/32 with the 5x giving 3350mm is good for planets but I think the 4x would have been a little better for flexibility.

Visual really requires as much light as possible.. the light per unit area of sky doesn't change but the light units that hit your eyes does as you change magnification. The total light is spread over more area in your eye - resulting in less light per rod/cone. The result is your eye gets less light per sensory rod/cone and it appears dimmer.. so adding more aperture is the required to add more light again.

The 2" form factor is heavy as others have noted - the 1.25" is far more portable and fits just as well for visual. The main thing is extending is better with a 2" than a 1.25" due to the rigidity of the connection but does add additional weight and will affect a previously setup balance. I use both for visual and imaging hence rigidity is needed and once fitted I'll stay with the 2x.

In the end it's about usability. What you'll use and maximising when you can use it. I use the 2x most with imaging and the eyepieces (I only have 3 EPs from the most used 10mm=67x, the 26mm 2"=25x (great for star hopping) and the 5mm=134x) and the 5x only gets used with planets/moon and solar when the turbulence is ok. However with DSOs often I'm back to just the 10mm due to light levels..