Best 3 EP's for a 300mm F5 dob

[ausastronomer (John Bambury)]

Originally Posted by davidpretorius

I am thinking:
UO orthos: 4mm & 5mm
Series 500: 6.5mm
Radian / Pentax: 7mm
Radian: 11mm
Series 500: 12.5mm
Series 500: 25mm
Panoptic 27mm
Andrews ultra wide 30mm
Panoptic 35mm

and a 2.4x barlow

David,

Before I answer you more fully can you tell me what the 2.4X barlow you have is ?

The only "good" quality 2.4X barlow that I am aware of is the 1.25" 2.4X Dakin barlow made by Vernonscope in the USA. Vernonscope are also the manufacturers of the Brandon eyepieces which are supplied standard with the "famed" Questar telescopes.

Any Optical "System" is only as good as its weakest link. If the barlow is poor the whole system will be poor

$5 telescope + $5 eyepiece + $5 barlow = $5 optical system
$5,000 telescope + $500 eyepiece + $300 barlow = as good as it gets $5,800 system
$5,000 telescope + $500 eyepiece +$5 barlow = $5 optical system

Hence you would be wasting your time using premium eyepieces with a 2nd rate barlow. If your barlow is a Dakin it will be fine, if its not there may be some issues using it with high quality eyepieces.

CS-John B

[ausastronomer (John Bambury)]

Originally Posted by janoskiss

Silly Bintel sods! That's the description and specs for the 9mm eyepiece. A 2" 32mm EP weighing 69 grams?

Steve,

Good call, I didnt even look at the weight of the thing

CS-John B

[davidpretorius]

I am thinking:
UO orthos: 4mm & 5mm
Series 500: 6.5mm
Radian / Pentax: 7mm
Radian: 11mm
Series 500: 12.5mm
Series 500: 25mm
Panoptic 27mm
Andrews ultra wide 30mm
Panoptic 35mm

and a 2.4x barlow

the bolded ones are the ones i am thinking of purchasing. The non bolded ones are what i have already. I would not be using them with this barlow. It is a cheap one.

I was going to go 2.5x powermate with the 7 and 11, but have ditched that and thinking 4 and 5 planetary eps. either uo's or vixens etc.

ie please disregard 2.4x barlow in calculations. It is iceman's old one! It is nice with the series 500, but i do not intend it to be giving me the range.

thanks john for your help

[Starkler (Geoff)]

Dave how often do you reckon you could get to use a 4mm ?
I would go a 5 and a 6 (we have the same scopes), with the 6 getting 80% of the use on planets.

[davidpretorius]

geoff,

weather ie clouds aside, i believe i am blessed with better than average seeing conditions here in tasmania. 6 stars in the trap over the last two month is the norm. (ie more than 50%)

i have been using the 12.5mm and 2.4x barlow (=5mm) alot on mars and saturn with pleasing results.

i have a 5mm lv to try of asimovs.

plus i am reluctant to discard the 6.5mm series 500 immediately. it is still an ok eyepiece.

yes eventually, a 4,5,6 in good planetary eps, 7, 11 (or 9,12) in a radian or pentax and then a great low power is my thinking.

on about 25% of the occassions, i have used the 6.5mm and the 2.4 barlow (less than 3mm) with satisfactory results.

This is my thinking and testing the 5mm vixen will soon help my final decision.
seeing is king, so if i am lucky with it here, i would like to make the most of it

Originally Posted by Starkler

Dave how often do you reckon you could get to use a 4mm ?
I would go a 5 and a 6 (we have the same scopes), with the 6 getting 80% of the use on planets.

[Stu]

Originally Posted by ausastronomer

Stu/Dobman,

You need to understand the difference between Apparent Field of View (AFOV) and True or Actual Field of View (TFOV).
CS-John B

Sorry to back track a bit but I haven't learnt how to use the "subscribe to thread" thing yet so I miss some replies...

John, I am very aware of the difference between AFOV and TFOV (which I just call FOV) and spend much of the night during the calculations in my head...
But what I was trying to say is that if I get (for example) a Nagler and a Panoptic with the same FL side by side (in my scope...one after the other), if I can see the field stop in the Nagler it gets me a bit because I feel ripped off.

If I struggle to see the field stop in a panoptic and can see it in a Nagler then I don't know how the Nagler could ever win my heart because the panoptic has other very slight benifits. Also I have found that some Naglers I can see the field stop and others I can't.

I think that Geoff solved the problem. Some of the longer focal length Naglers I am getting to close to (the lens). The field stop becomes much easier to see at that point and the image is not as good. I have to learn to step back a bit and then I might appreciate the disappearing field stop...

[janoskiss (Steve H)]

Stu, I think you have kind of answered your own question. When you cannot see the field stop in an eyepiece, it does not have enough eye relief.

You should be able to see the field stop in a good eyepiece, unless it is approaching close to 180 degree apparent field of view (not likely to happen within our lifetime). If you cannot see the field stop, i.e., the full field, you are missing out on some of the view, which defeats the purpose of having an eyepiece capable of presenting the full field. Am I making any sense?

[davidpretorius]

ok, just been comparing asi's vixen lv 5mm and it has a lovely field stop. I now know what one looks like. The 6.5mm series 500 is very unclear in its field stop.

great eye relief. colour abberations were similiar on mars as the series 500 around the edges. little fireflies occassionally ie reflections were a little distracting.

nice eyepiece. is it worth the $250, not sure????

by the way, mirror cooled to ambient, seeing at around 7/10. 6 stars in the trap. average detail on mars

[janoskiss (Steve H)]

Originally Posted by davidpretorius

colour abberations were similiar on mars as the series 500 around the edges. little fireflies occassionally ie reflections were a little distracting.

nice eyepiece. is it worth the $250, not sure????

Does not sound like it, esp. if it's a narrow AFOV EP.

[ausastronomer (John Bambury)]

Originally Posted by davidpretorius

nice eyepiece. is it worth the $250, not sure????

David,

IMO No its not. (Sorry john) These eyepieces are clearly inferior to their big brothers the Vixen LVW. They are a very good eyepiece, don't get me wrong here, but I think their are clearly better eyepieces available for less money.

I will send you a detailed reply to your earlier posts tomorrow. I will send it from work if I get a chance. My apologies as I did say I would do it today, but I was flat tack at work all day and its now quite late and I have to work early in the AM.

CS-John B

[davidpretorius]

Originally Posted by ausastronomer

My apologies as I did say I would do it today, but I was flat tack at work all day and its now quite late and I have to work early in the AM.

CS-John B

there is no need for you to apologise.

I am having fun learning. I was able to hold the vixen up to my eye and swirl it around like a wine buff noting the colour of the wine.

had no idea what i was doing, but i sure looked like i did.

I like the series 500, but it is nice to start comparing field stop etc, contrast

[asimov (John)]

Where did you pull that price from Dave?? An LV 5mm is down to $170-$180 I thought..

No need to apologise to me either John-B ....I just happen to be one of many around the world that own one of the LV line. At the time that I bought that EP I was truly uninformed & I was willing to buy anything rather than continue to use .965" EPs for visual use If I wasn't on a continuous budget I would have ended up with the most expensive EP rather than an vixen LV

Dave, try that EP on the trap & saturn etc before coming to a conclusion. I think that EP was the only one I have that could split antares. To solve the internal reflections on mars I used a contrast booster with it....But then I was getting some reflections from the filter itself! (Can't win!!)

[davidpretorius]

Originally Posted by asimov

Where did you pull that price from Dave?? An LV 5mm is down to $170-$180 I thought..

Dave, try that EP on the trap & saturn etc before coming to a conclusion. I think that EP was the only one I have that could split antares. To solve the internal reflections on mars I used a contrast booster with it....But then I was getting some reflections from the filter itself! (Can't win!!)

Asi, Latest AOS ad in the AS&T. it says from $250 and the LW's fro $385 i think.

No conclusions yet, just passing thoughts as i go along.

It is the best eyepice i have looked thru for any length of time. There was a few at star camp, but not a solid hour of observing like last night.

As i was explaining to my brother, it may well be a case of "Gee this grange hermitage tastes not better than cask wine!"

I have to ask myself with such little experience, do i really know what i am looking for in trying to compare ep's

This vixen was lovely with the field stop, very distinct at the edge and so the planet had a better contrast because of the fixed area of viewing. There was no fading off to the edge that the 6.5mm series 500 suffers from.

On axis and off axis, i have trouble comparing sharpness or contrast between the two. The trap looked better with this one.

I have a lot more experimenting to do. And i tell you what, i didn't touch the toucam at all last night, i was having far too much fun observing!!!

No one should get me wrong about the LV, am i having fun using, you bet, would i buy one, not sure yet!

[ausastronomer (John Bambury)]

Originally Posted by davidpretorius

gee you know your eyepieces. thanks!!!

Would you recommend the same for a f5 10" dob?

Hi David,

Finally !!!!!!!!! I got some time to answer this

I own the same scope as you and have used lots of different eyepieces in it so I can at least give you my thoughts on it. If I had to rate any one eyepiece as truly outstanding in my scope and my absolute favourite it would be the 10mm Pentax XW. If I was only ever allowed to use 1 eyepiece I could live happily with the 10mm Pentax. Remember however, that eyepieces are a very subjective thing and what suits one persons' observing style and preferences may not suit everyone. For instance I am not overly impressed by the enormous FOV phobia, that rows a lot of peoples' boats. I would prefer to accept a smaller FOV and have a smaller exit pupil which gives better contrast with my ageing eyes. There are only a few selected objects that you need a large FOV to observe, maybe 5 in the entire sky, over 1.5 degrees that aren't better suited in Binoculars. I prefer to have improved contrast on the 000's of other targets, than be able to fit those extra 5 targets in.

No I wouldn't quite recommend the same thing for the 10"/F5 scope as I did for the 12"/F5, due to its slightly shorter focal length but certainly pretty close and those options would work fine if you chose them.

Originally Posted by davidpretorius

Would you suggest a 35mm panoptic over a 27mm panoptic?

In my case definately not !!!! My maximum pupil dilation is about 6.0mm under dark skies consequently the 7mm exit pupil of the 35mm Pan causes a slightly washed out background and a loss of contrast. In the 10"/F5 scope the 27mm Panoptic gives 46X, a TFOV of 1.5° with a 5.4mm exit pupil which suits me perfectly, it provides excellent contrast and is very sharp to the EOF. I actually think the 27mm Panoptic is a fraction sharper than the 35mm Panoptic but they are both excellent. I recommended the 35mm Pan for the 12" scope due to its longer focal length. In the 12" scope the 27mm Panoptic gives 56X and a TFOV of 1.2°, consequently if the skies are dark I think the 35mm Panoptic is a better choice in that scope. If the skies are light polluted at all I would also recommend the 27mm Panoptic in the 12" scope as well.

If you have really dark skies (> Mag 6) have a pupil dilation over 7mm or very close to it and appreciate the larger FOV the 35mm Panoptic may be a better choice for you, but otherwise I would run with the 27mm Panoptic.

Originally Posted by davidpretorius

I have been thinking a 7mm radian or pentax, and a 11mm radian or pentax, based upon the number of times i have successfully used my combinations of the series 500 6.5mm and 12.5mm and the barlow.

Of all my eyepieces the 3 that get used the most (and by a good margin) are the 27mm TV Panoptic and the 10mm and 7mm Pentax XW's. My 10mm Pentax XW is easily my most used eyepiece as it creates the desired 2mm exit pupil which is ideal for most DSO observation. The 7mm Pentax XW also does exceptionally well for higher power viewing of DSO's and for medium power viewing of moon/planets and double stars. The 10mm gives 125X and the 7mm gives 180X.

Other options would be to go with 2 of 3 from say the 12mm, 10mm and 8mm TV Radians, or 2 of 4 from the 13mm,11mm,9mm and 7mm T6 Naglers. Having used them all, I rate the 10mm and 7mm Pentax XW's as marginally superior to the TV offerings as they are sharper on axis and have higher light transmission, I also find them the most comfortable to use with their 20mm of eye-relief and screw up/down eyecup. However, they are all outstanding eyepieces and you wouldn't go wrong with any of them. The Vixen LVW's are another excellent premium eyepiece option.

You need to think about what focal lengths may suit you the best and buy the eyepiece type that come in the right focal lengths to suit your needs, they are all very good but be aware of the eye-relief issues.

Some people would think there is too large a gap from the 27mm Panoptic to the 10mm Pentax XW. I also own the 20mm and 14mm Pentax XW's and rarely use them, invariably I go straight from the 27mm Panoptic to the 10mm Pentax XW. I think you need more eyepieces at the high power end than you do at the low/medium power end, others may not agree.

Originally Posted by davidpretorius

I do like your thoughts on a dedicated planetary ep instead of a powermate.

If you went with the eyepieces I have suggested thus far:

27mm TV Panoptic
10mm Pentax XW
7mm Pentax XW

I would add the 5mm and 6mm UO HD orthos as specialist planetary eyepieces and I think you would then have most options covered.

I agree with Geoff's comments concerning the 4mm volcano top ortho. I just don't think you would get to use it often enough and eye-relief is very tight, a lot tighter than the 5mm UO HD ortho in relative terms.

Originally Posted by davidpretorius

Plus i am reluctant to discard the 6.5mm series 500 immediately. it is still an ok eyepiece.

When you look through a Pentax XW or a UO HD ortho you will "see the light". About 20% more in fact than your seeing through that series 500 plossl

Originally Posted by davidpretorius

This is my thinking and testing the 5mm vixen will soon help my final decision.

The Vixen LV are a very good eyepiece and images are sharp. However I find the images a little dimmer and light transmission to be inferior to a high grade orthoscopic or plossl

CS-John B

[asimov (John)]

G'day John. http://myastroshop.com.au/ They did have the LV 5mm on site but it seems to have been taken off just recently.

After knowing what I know now, I'd have to say the pentax XW gets my vote (theres too many good reviews on it to ignore) although I've never used one! (hope to one day)

[asimov (John)]

BTW I paid $300 for that LV 5mm 2.5 years ago.... but that's the way the cookie crumbles! Not sure why but mars brings out the worst in that particular eyepiece.

[davidpretorius]

Mike, i have just voted for the first time on a thread. Can i also vote on the contributor???

John, i can't thank you enough for your efforts. This is an excellent summary on eyepieces that i have simply copied onto my computer to work through next to Bird's notes on processing! I wil have to digest it and go and do more research and of course trials, but I fell very confident that i am on the right track!

I will shut up now before i make an idiot out of myself!

thanks again!

[ausastronomer (John Bambury)]

Originally Posted by ausastronomer

The Vixen LV are a very good eyepiece and images are sharp. However I find the images a little dimmer and light transmission to be inferior to a high grade orthoscopic or plossl.

David,

I just followed the link that John posted to Steve Massey's website. The 6mm is $165 !!! Where did you get $250 from ?

At $165-00 you gotta think long and hard about them !!! They are marginally inferior in terms of light transmission to a high grade orthoscopic or plossl but the upside is the extra eye-relief and that is very important to some people. They have 20mm of eye-relief in each focal length and are very comfortable to use.

$165-00 is a good price and if you like them go for them. At $250-00 each they weren't such a good buy

CS-John B

[davidpretorius]

this months as&t ad for AOS i think.

it says "from $250" for lv and "from $385" for lw

i will check again.

when i was comparing last night, i had $100 to $200 in my mind from a quality point of view. I have looked (drooled) over the different suppliers of ep's in AS&T and the vixen have caught my eye every time along with TV's etc.

When I saw "from $250" i fell over and thought, "no way, not that good"

I will check DEC AS&T again tonight.

It is very pleasing to look through. Beautifully made and the view is nice. Mars still had chromatic abberations on the edges as it trundled across the fov. I really want to try the UO HD against this vixen. Saturn and jupiter need to be looked at as well!

[asimov (John)]

TV plossl is a good option as well. Chromatic abberations!? Don't remember seeing that in that EP.