Short EP's

[Stardaze]

I'm a little on the fence regarding an EP in the 6-7mm bracket. I'm building up my EP's slowly and consider the short end more for planetary use, so hoping to add at some point next month in readiness for Saturn/Jupiter, come July. 

I'm still a noob for the most part, but do like to 'future proof' these things best I can, so.... to that end, should I just plough straight in and buy something like a Delite? I was going to buy the OVL nirvana 4 & 7, which won't break the bank, but thinking long term... This will be for use in a 10" dob. 

Edited May 18, 2020 by Stardaze

[Ricochet]

Short term I would get something cheapish like a 7mm Nirvana or X-Cel LX, and/or barlow the longer focal lengths you already have. 

Long term I would find a binoviewer and barlow/gpc combination that will come to focus in your scope. Once you have that you can calculate the actual magnification the system is providing and figure out the focal lengths you will need with that. 

[Stardaze]

23 minutes ago, Ricochet said:

Short term I would get something cheapish like a 7mm Nirvana or X-Cel LX, and/or barlow the longer focal lengths you already have. 

Long term I would find a binoviewer and barlow/gpc combination that will come to focus in your scope. Once you have that you can calculate the actual magnification the system is providing and figure out the focal lengths you will need with that. 

That's a really sensible idea, thanks. Is this a relatively common practice for planetary viewing?

[Ricochet]

57 minutes ago, Stardaze said:

That's a really sensible idea, thanks. Is this a relatively common practice for planetary viewing?

It is quite common but not universal. Some people don't get on with binoviewers, some love them, but you won't know which camp you fall in to until you try it. Binoviewing for DSO viewing is quite uncommon as the combinations required for focus tend to limit FoV and exit pupil. 

[Stardaze]

Have been reading too many reviews, as you do! I'm going to build a full complement for now across the spectrum with a mix of ES 82's (11, 24) and the Nirvana's (16, 7, 4). I think at some stage, knowing me, I'll want to dabble with a TV to compare. The Delos 12 and/or a Nagler 22 look to be good starters for ten. One thing that reviews do seem to pick up on is the darker background of the Naglers. It could be that my EP's are showing a lot of light pollution but this is something I've noted quite a bit. 

[Stardaze]

@John away from the 100 degree £600 TV Ep's, what are your personal views on some of the £3-400 TV's? A panoptic 35 would provide a similar FOV as the ES 24 (82) but the 16/17 area seems to be quite divided. Many people seem to deviate towards 11/12, which I need to use and review. It's all hypothetical and no rush, but good to hears others thoughts/mistakes/regrets😀

[John]

1 hour ago, Stardaze said:

@John away from the 100 degree £600 TV Ep's, what are your personal views on some of the £3-400 TV's? A panoptic 35 would provide a similar FOV as the ES 24 (82) but the 16/17 area seems to be quite divided. Many people seem to deviate towards 11/12, which I need to use and review. It's all hypothetical and no rush, but good to hears others thoughts/mistakes/regrets😀

In that price bracket I currently own the 24mm Panoptic, the 17.3mm and 14mm Delos and the 2-4mm Nagler zoom. I'm very happy with these and don't see any need to change them in the foreseeable future.

In between those focal lengths I use Pentax XW's which are less expensive but, to my eye, just as nice as the Delos.

I've yet to use a TV Delite though, and those get really good feedback. The Baader Morpheus likewise and they quite cost quite bit less than the Delos and the XW's.

 

 

[Stardaze]

1 hour ago, John said:

In that price bracket I currently own the 24mm Panoptic, the 17.3mm and 14mm Delos and the 2-4mm Nagler zoom. I'm very happy with these and don't see any need to change them in the foreseeable future.

In between those focal lengths I use Pentax XW's which are less expensive but, to my eye, just as nice as the Delos.

I've yet to use a TV Delite though, and those get really good feedback. The Baader Morpheus likewise and they quite cost quite bit less than the Delos and the XW's.

 

 

How do you find the Panoptic? Is an EP collection something of the norm 😆

[JTEC]

I’d concur with John on the mid-price 🤣 Televues.  I have the Delos in 8 and 10 and have used a friends 6 and 17.3.  I’ve tried lots of eyepieces over the years and concluded that, for a middling afov eyepiece, the Deloses are about as good as you’ll get. I’ve now built in the Pentax XWs to cover the 5 and 7 f lengths. There are differences in feel and handling between the two ranges but I spent some hours staring at globulars the other night looking for meaningful differences - could I see more with one or the other, was either one sharper, giving better contrast, etc - and concluded that they were both pretty much as good as each other. Which is to say excellent.  If I’d started out with the Pentaxes, I’d probably be building a set round them, rather than the other way round.

[John]

16 minutes ago, Stardaze said:

How do you find the Panoptic? Is an EP collection something of the norm 😆

The 24 Panoptic is very compact compared with the Delos's (Deloi ?). Smaller eye lens and not quite so immersive. It's focal point is around 8mm further out than the 17.3 and 14mm Deloi and the Pentax XW's so I might start using a par-focal ring on the Panoptic to equal that up a bit. It's not a show stopping issue though.

The other Delos focal lengths (12mm downwards) are the same as the Panoptic - Tele Vue's focal point "B".

 

 

[Stardaze]

24 minutes ago, JTEC said:

I’d concur with John on the mid-price 🤣 Televues.  I have the Delos in 8 and 10 and have used a friends 6 and 17.3.  I’ve tried lots of eyepieces over the years and concluded that, for a middling afov eyepiece, the Deloses are about as good as you’ll get. I’ve now built in the Pentax XWs to cover the 5 and 7 f lengths. There are differences in feel and handling between the two ranges but I spent some hours staring at globulars the other night looking for meaningful differences - could I see more with one or the other, was either one sharper, giving better contrast, etc - and concluded that they were both pretty much as good as each other. Which is to say excellent.  If I’d started out with the Pentaxes, I’d probably be building a set round them, rather than the other way round.

 

17 minutes ago, John said:

The 24 Panoptic is very compact compared with the Delos's (Deloi ?). Smaller eye lens and not quite so immersive. It's focal point is around 8mm further out than the 17.3 and 14mm Deloi and the Pentax XW's so I might start using a par-focal ring on the Panoptic to equal that up a bit. It's not a show stopping issue though.

The other Delos focal lengths (12mm downwards) are the same as the Panoptic - Tele Vue's focal point "B".

 

 

There's a little too much choice in the TV ranges. Subtle differences between each range too doesn't help, huh 😂 I have time to do some research as to where I'll, no doubt, dip my toe first.

[Ricochet]

4 hours ago, Stardaze said:

A panoptic 35

Was it the 8" f6 or 10" f5 you bought? A 35mm eyepiece would give an exit pupil of either 5.8mm or 7mm, which will likely give you a washed out background under light polluted skies. 

[Stardaze]

22 minutes ago, Ricochet said:

Was it the 8" f6 or 10" f5 you bought? A 35mm eyepiece would give an exit pupil of either 5.8mm or 7mm, which will likely give you a washed out background under light polluted skies. 

10” f5. The calc I saw was nearer 6 but could be wrong. Understand 7 is the limitation in general but I do hlstill have very good vision so would like to think I’m the upper end?

[Stardaze]

@Richochet you are right, it is 7mm for the 35mm. 👍

[Ricochet]

27 minutes ago, Stardaze said:

10” f5. The calc I saw was nearer 6 but could be wrong. Understand 7 is the limitation in general but I do hlstill have very good vision so would like to think I’m the upper end?

It's nothing to do with your vision compared to someone else's . The brightness of extended objects increases with exit pupil so the bigger the exit pupil, the brighter the sky background. This results in a loss of contrast between stars and the background sky. You've got a 24mm, so you can see the brightness of the sky in that. A 35mm will have a sky brightness roughly double that of the 24mm, which due to the way your eye works will appear as one "step" brighter so you can use that gauge whether you think a 35mm will be too bright. Your 11mm is roughly a quarter as bright as the 24mm, so two steps darker to your eye. 

[John]

10 minutes ago, Ricochet said:

It's nothing to do with your vision compared to someone else's . The brightness of extended objects increases with exit pupil so the bigger the exit pupil, the brighter the sky background. This results in a loss of contrast between stars and the background sky. You've got a 24mm, so you can see the brightness of the sky in that. A 35mm will have a sky brightness roughly double that of the 24mm, which due to the way your eye works will appear as one "step" brighter so you can use that gauge whether you think a 35mm will be too bright. Your 11mm is roughly a quarter as bright as the 24mm, so two steps darker to your eye. 

As above. This is the reason that my Ethos 21mm gets more use than my Nagler 31mm when I'm using my F/5.3 12 inch dobsonian.

 

[Stardaze]

15 minutes ago, Ricochet said:

It's nothing to do with your vision compared to someone else's . The brightness of extended objects increases with exit pupil so the bigger the exit pupil, the brighter the sky background. This results in a loss of contrast between stars and the background sky. You've got a 24mm, so you can see the brightness of the sky in that. A 35mm will have a sky brightness roughly double that of the 24mm, which due to the way your eye works will appear as one "step" brighter so you can use that gauge whether you think a 35mm will be too bright. Your 11mm is roughly a quarter as bright as the 24mm, so two steps darker to your eye. 

That makes sense, thanks.

[Stardaze]

8 minutes ago, John said:

As above. This is the reason that my Ethos 21mm gets more use than my Nagler 31mm when I'm using my F/5.3 12 inch dobsonian.

 

That’s the balance you need to find then. Could be a costly exercise 😂 

[John]

Just now, Stardaze said:

That’s the balance you need to find then. Could be a costly exercise 😂 

There are less expensive alternatives than those in fairness.

 

[JTEC]

2 hours ago, Stardaze said:

 

There's a little too much choice in the TV ranges. Subtle differences between each range too doesn't help, huh 😂 I have time to do some research as to where I'll, no doubt, dip my toe first.

... it’s another way of saying that we’re spoilt for choice 😊.  In terms of optical quality, they’re both, to my eye in my 140mm f7 apo, excellent.  The differences are in form factor, handling preference, comfort, type of eye-guard, etc, I think, not in how well they deliver optically. These are personal things and you need to get a look at some to see whether they matter to you. Personally, I don’t find them important and am happy to mix ranges to get things covered the way I want. Another not trivial consideration is that the Pentaxes are a lot less expensive than the Delos. 

 

[Stardaze]

59 minutes ago, John said:

There are less expensive alternatives than those in fairness.

 

I’ll spend some time working with what I have this year, to suss where the upgrade (s) would be beneficial. For me, the 40-70x is probably where I spend most of my time. 

Edited May 19, 2020 by Stardaze

[Louis D]

5 hours ago, JTEC said:

Another not trivial consideration is that the Pentaxes are a lot less expensive than the Delos.

Right now, only $53 difference in the states, so not that big of a deal.  The XWs only recently dropped in price here.  There used to be little to choose between them on price.  Tele Vue does put their stuff on sale once in a while here bringing the two closer.

[JTEC]

Yes, significant difference over here at this time though, Louis:  £336 Delos  £249 Pentax XW. Adds up if you commit to a set.