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Do you need a 17.4mm if you have a 14mm?

JOC

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DHEB

DHEB

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Personally, I believe it is not a big difference in native magnification, but these eyepieces will possibly deliver different viewing experiences if barlowed, for example. Very good question in any case, I will be watching for answers.

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Sunshine

Sunshine

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I have found that with my Mak on planetary going from a 9 to a 7 was the difference between  a good and not so good image. Just that 2 mm difference,seems to have crossed the line for a particular nights seeing conditions.

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JOC

JOC

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1 minute ago, Sunshine said:

9 to a 7

I also find that the jumps seem larger as the EPmm get smaller and have noticed a similar effect.  On the other hand if the difference isn't worth having then why do manufacturers make both sizes within the same set of EP's?  Is it just to get more cash from folks that want a whole box of the same colour (not that I'm considering doing this of course ?)

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DHEB

DHEB

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4 minutes ago, Sunshine said:

I have found that with my Mak on planetary going from a 9 to a 7 was the difference between  a good and not so good image. Just that 2 mm difference,seems to have crossed the line for a particular nights seeing conditions.

Yes, it is a well known phenomenon that going up in magnification darkens the background, therefore by increasing the contrast, some objects become more easily visible.

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michael.h.f.wilkinson

michael.h.f.wilkinson

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I have a 12mm Nagler, 14mm Delos, and 17 mm, 22mm Nagler for mid-range magnification DSO hunting. The 12 mm doesn't get used as much as the 14, but I use 14, 17, and 22mm frequently use all three. Subtle changes in exit pupil can help a lot in pulling out detail on different DSOs

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Louis D

Louis D

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1 hour ago, Alan White said:

Or are you allowing the equipment-want monster to take charge?

It took a few re-readings, but I think a well placed hyphen helps to clarify your comment.

I started out with a 14mm Pentax XL in the mid-power position and was happy and content for years.  Then my wallet fattened as I hit mid-career and my "want monster" took over.  I added 12mm and 17mm NT4s and was again content for a few years.  Then the ES-92s came out and I knew I needed them, so I got them.  I then swapped out the XL for a 14mm Morpheus.  Again, because I wanted to try something different.  Each shows the same view slightly differently which can make for an enjoyable evening playing with my toys in the quiet of my backyard without any distractions.

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Louis D

Louis D

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17 minutes ago, Ricochet said:

I use 1.4x steps as the basis for my DSO eyepieces, which makes the step down from 14mm a 20mm eyepiece. However, so far I've been happy with a gap at 20 and jump straight from 14 to 28. 

For years, I used 2.7x jumps.  38mm, 14mm, and 5.2mm were my three eyepieces for years, and I was quite content.  Now I have 50 eyepieces and am probably less contented than I was then.

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Louis D

Louis D

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1 minute ago, JOC said:

LOL, luckily I 'got it' the moment I read it.  The 17mm is a beautiful object!.............

You never did say which 17mm eyepiece you were interested in getting.  Your title had 17.4mm, but I can't find an eyepiece of that focal length.  There is the 17.3mm Delos which is closest.

Your comment said 17.5mm which could be either the Baader Morpheus or Nikon NAV-SW.

As I said above, I have the 17mm NT4 and ES-92 along with the AstroTech AF70 as shown below.  I haven't ever tried the Delos, Morpheus or NAV-SW because the TV and ES seemed good enough at that focal length.  If I needed a 1.25" option, I just removed the 2" skirt from the AF70.

556015058_17mmEyepieces1.thumb.jpg.2cf61115172b160c6c31eb957d4c7913.jpg

1018497556_17mmEyepieces3.thumb.jpg.9b2c481a6bca299dc1091db9bf0e3955.jpg

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Alan White

Alan White

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15 minutes ago, JOC said:

LOL, luckily I 'got it' the moment I read it.  The 17.4mm is a beautiful object!.............

I am glad you did JOC.
It is something that festers in so many of us, me included, to want rather than need something.
The Astro Want Monster or 'AWM' is a terrible beast to resist at times.
Just look in my dining room and you can see the devastation it brings.......ooops don't read that bit Mrs W!

You wait until the AWM drives scopes as well as eyepieces, then you are in trouble.......don't read that either Mrs W!

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bomberbaz

bomberbaz

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I go from 26-17-12.5 then reach for the powermate. When using the powermate I end up screwing the EIC focal barlows to the eyepieces. 17 becomes 14 and 12.5 become 10.

As mentioned above I also prefer to have a tighter group for high powered viewing (8.5-7-6.25-5) 

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cloudsweeper

cloudsweeper

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Get it - there's something lovely about these things.  I got another new one just yesterday.  Probably got more than I truly need, but it can be nice to have small increments at your disposal.

But being more practical, the exit pupils for the FLs given are both between 2 and 3mm, so that's another reason why they might not both be necessary.  The changes in exit pupil values are more pronounced at longer FLs, with fast 'scopes.  High exit pupil figures give a brighter background sky and thus poor contrast.

Doug.

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fwm891

fwm891

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Interesting this thread. I have a 2" 30mm 70° that came with the Dob to which I've added a 24, 20 and 14mm plus a 2x barlow. Giving me: 30, 24, 20, 14, 12, 10 and 7mm - I'm hoping I can live with that range (for a while anyway!)

Francis

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Moonshane

Moonshane

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I think it depends on the scopes you have. In my 120 equinox at 900mm focal length the difference would be 51x and 64x so not worth it. In my 16" dob at 1840mm it would be 105x and 131x so maybe but still not really worth it. If you had a 12" sct at say 3000mm it would be 172x and 214x. This could be important depending on seeing.

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