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8mm or 10mm Delos?

TwoPi

By TwoPi
in Discussions - Eyepieces

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TwoPi

TwoPi

Posted
Posted

Hello again.

One last piece of procrastination before I put my hand in my wallet... :rolleyes2:

As a recap, I'm planning to replace my stock SkyWatcher 10mm plossl with a Delos.

Following my earlier thread I was all ready to go with the 10mm Delos (and the 3-6mm Nagler zoom for lunar/planetary work!) when it occurred to me to calculate the field of view in my scope - it will come to 0.61°, vs 0.43° for the SW 10mm (FYI, 10mm EPs = 120x magnification with my scope).

Thinking back to my views through the SW eyepiece, I've always been reasonably happy that globular clusters and the like comfortably fit and so I thought I'd take a quick look at the 8mm Delos. This comes in with a FOV of 0.47° and 150x magnification in my scope, so still a (slightly) larger FOV than my SW 10mm but with an increase in magnification.

I assume objects won't be quite as bright in the 8mm eyepiece (but then again, the contrast will be slightly higher) - so is there anything else to consider or given I'm happy with a FOV of <0.5°, should I actually replace my 10mm SW with an 8mm Delos rather than a 10mm Delos?

Thanks as ever for your thoughts!

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alan potts

alan potts

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Posted

Believe it or not that was what i was going to say.

I would go for the 8mm for the extra magnification, it would make a very good globular cluster eyepiece, I feel X120 is just a little low for this. It would also make a better power for  planets. I have a few scopes and X120 is a power that I don't use very much, I tend to go from X60-80 up to about X160 on most of my scopes. It really comes down to what you look at the most.

I have just done a fairly long head to head with the 24mm and 26mm eyepieces I have, this gives around X120 in one of my scopes and a bit less in another, I was using the Moon as a few members  wanted me to include this in some of my write-ups, I have to say I did not like this power on the Moon but of course this is only my preference not law.

BTW, I don't know how large your scope is but I don't feel that an extra X30 will make so much difference in brightness, it does not in my scopes

Alan

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Pig

Pig

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Posted

Hiya,

Due to the rather large focal length of my scope (2350mm) there is quite a difference between the 2 eyepieces. On my brothers scope (1500mm FL) its not so different but still quite noticeable.

As Alan stated above it rather depends on what you want to use it for, if its for the Moon/planets I would go for the 8mm, if it is for the stars or both stars & planets I would go for the 10mm.

You are in a premium position whichever one you decide to buy  :smiley:

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Qualia

Qualia

Posted
Posted

Ay, TwoPi. Ask a question at SGL and you're going to get more possible suggestions than a philosophers' round table :grin:.

In the 10" f/5, I use a 10mm Delos which gives 125x - 2mm exit pupil and 0.57º TFOV. I've found this to be a comfortable magnification to do 90% of my general deep celestial viewing and sketching, on objects such as globulars, galaxies, nebulae, tight clusters etc. At this magnification, the EP also has a decent TFOV to frame the Moon perfectly which is a joy in itself. If the given DSOs are not playing game, or atmospheric conditions are a biit rough, I'll drop down to 90x. But if I feel that a given DSO will be able to take more magnification in the 10" (and not all of them will) I'll just up the power but only in small steps of about 10% to 15%. Sadly, I cannot afford, nor lug about a full set of Delos eyepieces, so I use BGOs for this task.

At 156x, I'm not generally beginning to observe and tweak details from DSOs but more framing planets such as Jupiter or Saturn. Again, I've found that 90% of my observing and sketching on these gas giants is being done either at 178x or 208x. And this follows true for the Moon as well. Sometimes I'll kick the power up to 250x, drop down to 150x but its a rare occassion that I'll begin sketching or significantly viewing at these powers.

Moonshane once gave me some very sound advice which has served me well. When I was running into the same dilemma, he suggested that I get my some plossls of the magnification I was thinking about and practice with them for a good number of nights. That way, I'd get a feel of the general sky conditions in my area, how the given scope and eye performed on the given objects I was wishing to observe. Once a decission had been made the plossls could be kept for a light-weight set of grab and go EPs or if of decent quality (such as TVPs) could always be sold on with very little, if any, lose (especially if bought 2nd hand).

Hope I haven't caused too much of a headache :smiley:

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TwoPi

TwoPi

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Thanks as ever, plenty to think about. I'm going to have one last play in Stellarium to see what the 8mm will give me on various objects and then suspect I will go for this option.

I think I'll probably be satisfied with my 16mm (75x) going straight to 8mm (150x).

If not, there's always a 12mm for Christmas! (shoot me now) :)

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michael.h.f.wilkinson

michael.h.f.wilkinson

Posted
Posted

Thanks as ever, plenty to think about. I'm going to have one last play in Stellarium to see what the 8mm will give me on various objects and then suspect I will go for this option.

I think I'll probably be satisfied with my 16mm (75x) going straight to 8mm (150x).

If not, there's always a 12mm for Christmas! (shoot me now) :)

And the 10, and the 14 :evil6:

;)

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John

John

Posted
Posted

I'm a bit late to this but my inclination would be towards the 8mm too I think. 

Why is it that such expensive eyepieces are also so addictive ? 

I'm sure many of us have been through the phase of having pretty decent eyepieces, thinking that just adding one Tele Vue to "round the set off" is a good idea and then finding, within a few months that the eyepiece case is lined with black and green and the bank balance is somewhat lower   :undecided:

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Pig

Pig

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Posted

I'm a bit late to this but my inclination would be towards the 8mm too I think. 

Why is it that such expensive eyepieces are also so addictive ? 

I'm sure many of us have been through the phase of having pretty decent eyepieces, thinking that just adding one Tele Vue to "round the set off" is a good idea and then finding, within a few months that the eyepiece case is lined with black and green and the bank balance is somewhat lower   :undecided:

I couldn't agree more :laugh:

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jetstream

jetstream

Posted
Posted

2pi do you have a chance to try some of these & other eyepieces out first?I mean you can't go wrong with a Delos,but using a few different eyepieces may influence your decision as to which ones...My 8mm Delos is fantastic in my 90mm,but I tend to like lower mag/wider field for a lot of my observing & then "hone in" on certain objects at higher power.Can't wait to here the decision(s).You are gonna be happy! :smiley:

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Bart

Bart

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Posted

I'm a bit late to this but my inclination would be towards the 8mm too I think.

Why is it that such expensive eyepieces are also so addictive ?

I'm sure many of us have been through the phase of having pretty decent eyepieces, thinking that just adding one Tele Vue to "round the set off" is a good idea and then finding, within a few months that the eyepiece case is lined with black and green and the bank balance is somewhat lower :undecided:

Somewhat??? Master of the understatement, John :):)

Barry

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Naemeth

Naemeth

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Posted

Yes, I can't help thinking this is the start of a slippery slope / mountain side / cliff... ;)

It is indeed. I'll honestly be surprised if, a year from now, you don't have the 8mm, 10mm, 12mm, 14mm and 17.3mm ;).

I'll be surprised if I don't too ;).

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bingevader

bingevader

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Posted

In fear of being shot down in green flames, had you considered the ES 8.8mm and 11mm EPs?

They're 82o and you could get both for the price of the Delos!

Unless you're imminently upgrading your 'scope to something bigger and faster, they'd be a good deal more than adequate in a Skyliner.

Runs and hides....

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swamp thing

swamp thing

Posted
Posted

In fear of being shot down in green flames, had you considered the ES 8.8mm and 11mm EPs?

They're 82o and you could get both for the price of the Delos!

Unless you're imminently upgrading your 'scope to something bigger and faster, they'd be a good deal more than adequate in a Skyliner.

Runs and hides....

At f/6 I reckon your right. Unless panning a fast scope I'd save a few bob too. :)
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