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FC100D under suburban skies.

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#1 Kevin McCarthy

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Posted 25 April 2019 - 12:54 PM

So I have had my FC100D for just over two years. I scrimped and saved and finally I became the owner of a quality refractor. I sold a lot if equipment and went back to bare bones keeping the very minimum to get by with. I wisely kept my old powermate 2.5 and bought a 9mm delite. The views have been so good I am often heard laughing in the back garden in the night. I kept an old vixen 7mm LV and a not so old 17mm Hyperion.

I am in a position were I can pick up a couple of quality eyepieces. I wear glasses, cant imagine anything more than 68 degrees FOV would work for me and live under suburbans skies.

Moon, planets and open clusters typical stuff. I need a finder eyepiece no matter how good the finder scope is I cant get on with getting on my knees and twisting my kneck. I do enjoy star hopping but a 17mm hyperion and suburban skies can make it tricky.

In my mind I have HP MP LP and finder EP's or on my spreadsheet at least but am interested in your choices without debating mine.

Thanks in advance.

Edited by Kevin McCarthy, 25 April 2019 - 12:58 PM.

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#2 Starman1

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Posted 25 April 2019 - 01:28 PM

Kevin,

My own 102mm f/7 apo is Hoya FCD-1 glass, so a bit below the correction of yours.

Yet, when in focus, there is no visible chromatic aberration, even at 238x.

I, too, am surprised at how good the star images can be.  I keep both the focuser and the lens assembly collimated, and, luckily, I did not have

to center any of the 3 objective elements.

 

As for eyepieces, I can only relate my own considerations:

I needed long eye relief, not because I need it, but because this scope sees a lot of outreach.

I wanted eyepieces completely free from astigmatism.

I wanted eyepieces with good contrast and as close to zero scattered light as I could find.

Due to the short focal length, I could get an acceptably wide field with 1.25" eyepieces.  A 24mm Panoptic yields 2.17° which, while nowhere near as wide as

is possible, yields an exit pupil small enough I don't need to wear glasses or use a DioptRx, and is wide enough for nearly any target I would look at in the 4".

 

So, the 24mm 68° TeleVue Panoptic was my choice for low power.  I cannot complain about sharpness or correction or eye relief, though it violates my rule about eye relief.

Typically, I don't go this low (30x) in magnification because of the targets chosen, but it works.  A 22mm Nagler would yield a wider field and longer eye relief, and I might go there

eventually.

As for the rest of the focal lengths, I have a complete set of TeleVue Delites, which I find exemplary for correction, contrast, and spot size.

I chose them because I wanted this scope to be as sharp as possible for its aperture.

I have found their equals in sharpness in some narrower field eyepieces, though not their equals in edge of field correction.  And, after years with 100-120° eyepieces,

I find 62° about as narrow as I care to go.  It still seems narrow, but the fields are wide enough with the short focal length scope.  If the focal length of the scope were longer,

I might have opted for 70° or more.

 

Having the complete set, I would argue that one does not need the full set of Delites to provide adequate magnification choices.

I will probably pare my set down to:

24mm, 15mm, 9 or 11mm, 7mm, 5mm, 4mm, 3mm.

The 18.2mm Delite is used a lot, though, so it seems difficult to part with that one.  And the 13mm seems to spend a lot of time in the focuser as well, so another one to keep?

Aw, I just have to face it--I like having the whole set, because each plays a rôle in the framing of particular targets.

 

Now, if keeping it economy, there are some very nice inexpensive long eye relief eyepieces out there (22mm Olivon 70 comes to mind--it works really well in the apo), and if you don't mind the price of the Delites but want wider fields, the Baader Morpheus comes to mind, or the APM UltraFlatField.  I recommend an eyepiece to yield ~50x and another to yield ~100x.  Other than that, your choice.

I suggest downloading the Eyepieces Buyers Guide at the top of the eyepieces forum and then whittling it down to your possibles and then getting feedback on these forums.



#3 Ihtegla Sar

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Posted 25 April 2019 - 01:34 PM

Congratulations on your purchase!  Which "D" did you get?  I just recently got a FC100DL.  I am just getting back into astronomy after a 25 year hiatus and like you I am mostly looking at the moon, planets, a few double stars and bright open clusters from a heavily light polluted area on my deck.  I can give you my experiences but I have only had the Tak for about a month so I don't have a lot of experience.  Also, I wear glasses for extreme nearsightedness but I was blessed with no astigmatism, so I don't wear glasses when viewing -- so eye relief isn't an issue for me.

 

I will start by saying if you can get it out to a dark sky then a 24mm Panoptic is phenomenal to just scan across the sky and stop to view open clusters, and also as a finder eyepiece.  The ES 14mm 82 degree was also nice.  I wasn't able to go much higher than that in magnification because things started getting a bit too dim for my tastes for deep sky objects with the 4 inch aperture -- I am used to a C-8 -- and I was not able to resolve any individual stars in M13 or M3 in the FC100DL.  But the Beehive and M67 open clusters were very nice to look at in both the 24mm pan and the ES 14mm.  I tried my old 30mm Celestron Ultima and my 28 mm RKE in the dark skies but the 24 pan seemed to have a lot more pop to it.  Everything just looked a bit cleaner and sharper than those lesser eyepieces.  Usually I cannot tell much difference between eyepieces of similar focal lengths but the 24 Pan did stand out for me in the dark sky.  I haven't really spent too much time with it in the City through.  I have a hard time getting excited about viewing washed out deep sky objects in the City after having viewed them at a dark sky, and I can get to a dark sky pretty easily on weekends if I want to do a whole night of observing.  But for weeknights, the Tak is fantastic to  drag out on the deck to look at the Moon or planets for an hour when I have time and weather permits.

 

For the City, I have been mostly looking at the Moon and Jupiter and a few double stars -- things that light pollution doesn't interfere with. Mostly I using ES 4.7 and 6.7 82 degree, an ES 9mm 100 degree, a Delite 7mm and a Delos 4.5 mm in town.  Other than the 24 mm Pan really standing out in a dark sky, I honestly cannot tell you which of those eyepieces are "better" or what the differences are (besides the obvious magnification and FOV differences). 

 

Most of the time I am so impressed with the view through the Tak that it doesn't matter what eyepiece I am using, it always looks like the "best" eyepiece on the planet, as long as I am not trying to magnify it too much for the seeing -- then it gets soupy but its not the fault of the telescope or eyepiece.  


Edited by Ihtegla Sar, 25 April 2019 - 01:39 PM.


#4 Kevin McCarthy

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Posted 25 April 2019 - 03:03 PM

Don.

 

Thanks for your comments.

"A 24mm Panoptic yields 2.17°...and is wide enough for nearly any target I would look at in the 4..."

   the 24mm Pan. keeps popping up but I dont think I can live woth the eye relief though the 27mm might suit me more but I wounder if the mag. is getting to low for my skies..

 

"I have a complete set of TeleVue Delites, which I find exemplary for correction, contrast, and spot size..."

   I really like the delite I have. I coundlt do that, too many options and I end procrastinating.

 

 

The 18.2mm Delite is used a lot, though, so it seems difficult to part with that one.  And the 13mm seems to spend a lot of time in the focuser as well, so another one to keep?

    I dont know if I would pick up two so close in focal length so I will split the difference with you and say 15mm !

 

regards Kevin.



#5 Kevin McCarthy

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Posted 25 April 2019 - 03:23 PM

Steve.

 

Thanks its been an exciting time since reciving it.

 

I am looking for a much more stable and portable tripod as well its something that frustrated me last year when mars spent the summer behind the trees. It made me realise that if i could get my scope in the car and drive up the road I could get a great view of the souther horizon. So I expect to be a bit more mobile this summer. I made my current mount from wood and ten years old. It tall and the legs are fixed it does have to move far.

 

24mm Pan is mentioned again!  Making the most of the moon and planets in a telescope with sharp optics is so rewarding in a light polluted area. Its great when you come in and feel good with what you have seen. It why I had to get a good refactor.

 

How does the ES6.7 compare to the delite 7mm on the moon?

 

Regards Kevin.


Edited by Kevin McCarthy, 25 April 2019 - 03:24 PM.


#6 Ihtegla Sar

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Posted 25 April 2019 - 03:58 PM

For mounts, I am really enjoying the Meade LX70 I just got. Its much better than the CG-4 I had been using. Although an alti-azimuth would be more portable.

I know what you mean by trees blocking the planet. My deck offers a view of the sky to the south and south west but south east is blocked so I have to either go out in the yard or up the street or wait until after 3:30 am for Jupiter to swing past the trees.

As far as ES 6.7 vs Delite 7, I think the ES compares well for the price, especially the sale price I purchased it for, and I like the fit and finish of ES eyepieces and the fact they are waterproof. However, the Delite is deliteful and I have to give it a slight edge over the ES, especially on the moon. If I had to pick one eyepiece from my set as my only eyepiece to view the moon or Jupiter, it would be the Delite 7mm. I probably would have bought more of that series if it hadn't been for the ES sale and I will probably add to my Delite collection over time. But I paid $150 for the ES and $250 for the Delite, so thats 66% more money, and I would say the Delite is only maybe 10-20% more deliteful than the ES. And I have never really tried either with my glasses so have no opinion on the differences in eye relief, but the Delite does have a sliding barrel that lets you set the eye relief for best head placement. The ES doesn't have that feature.

#7 Starman1

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Posted 25 April 2019 - 04:04 PM

The ES 6.7mm 82° is a decent eyepiece.

Eye relief is tight at 14mm (claimed) but it feels tighter than that.

 

Ernest's Russian analysis (I cleaned up the translation):

"At f/4:  A good image of a star on axis is less than 6' of arc. At the 70% zone (70% from the center to the edge) the image of the star is increased to 10 arc-minutes due to astigmatism and field curvature. At the edge of the field of view (one and a half degrees from the field stop), the aberration spot has a size of 13-14 arc-minutes The main aberration is astigmatism with a slight increase in chromaticism. Moderate positive rectilinear distortion (pincushion).
At f/10: Field aberrations are slightly smaller: 6-7 arc-minutes at the 70% zone and 10 arc-minutes at the edge."

Observing at the exit pupil is comfortable enough for observations without glasses. With daytime observations, “kidney bean vignetting” is rather unpleasantly annoying."

 

So, in summary:

Not super sharp on axis, but probably pretty good by f/6 or so, but a bit blurred at f/4. [5' of arc would appear point-like at low power, but perhaps not at high power.]

Not perfect at f/10 at the edge, though better than most, but the center 70% of the field is nice and sharp.

Not good for daylight viewing due to aberration of the exit pupil.

He measures 13mm eye relief from the rubber eyecup. 

A pretty good result for the price.

Here is the link:  http://astro-talks.r...topic.php?t=535


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#8 havasman

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Posted 25 April 2019 - 04:47 PM

I've owned 30, 18, 6.7 and 4.7mm ES82's and the 6.7 was the lowest performing of the group by a good bit in my scopes. The other 3 were very good. All those have shorter eye relief than most folks with ER sensitivity are comfortable with.

 

The ES62 26mm has gotten some high praise from experienced observers here in the forums and has longer ER. It might be a useful alternative to the 24Pan/ES68 24mm which I also was going to recommend. I think we all want you to have a better widefield option. But you know your habits and location best.



#9 Kevin McCarthy

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Posted 25 April 2019 - 05:02 PM

As far as ES 6.7 vs Delite 7... But I paid $150 for the ES and $250 for the Delite, so thats 66% more money, and I would say the Delite is only maybe 10-20% more deliteful than the ES. ...


Value for money is always a big consideration.

#10 Kevin McCarthy

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Posted 25 April 2019 - 05:06 PM

Starman1.

That last 30% bothers me in the Hyperion as well. So I am all for avoiding it this time around.

Kevin

#11 Kevin McCarthy

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Posted 25 April 2019 - 05:11 PM

Havasman.

Yeap, I know my location but not naglars and panoptics and the like. I have over the years used slightly smaller focal lengths than some what with the light pollution but want for a bigger but sharper FOV etc.

Kevin.

#12 AxelB

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Posted 25 April 2019 - 05:27 PM

After completing my ES82 collection, I’m now in the process of replacing the focal length I like less. This year I ordered an ES92 17 to replace the 18mm. Next year I’ll probably upgrade the 6.7mm. It’s not bad but I would appreciate more eyerelief and a less finicky eye placement. The 7mm Delite is a possible option for me, not sure yet because 62 degree is a bit narrow. I mostly use it for planetary with a tracking mount so it may be ok 80% of the time.

Edited by AxelB, 25 April 2019 - 05:40 PM.


#13 Mr. Mike

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Posted 25 April 2019 - 05:53 PM

Can I suggest the 6.5 Baader Morpheus?  Lots of eye relief, super comfortable, priced about right and the contrast/sharpness are excellent.  Prolly be a great fit for someone with glasses!  Oh, and it has a very usable 76 degree AFOV which IMO is perfect for just about any target! 


Edited by Mr. Mike, 25 April 2019 - 05:54 PM.

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#14 Ihtegla Sar

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Posted 25 April 2019 - 06:15 PM

After completing my ES82 collection, I’m now in the process of replacing the focal length I like less. This year I ordered an ES92 17 to replace the 18mm. Next year I’ll probably upgrade the 6.7mm. It’s not bad but I would appreciate more eyerelief and a less finicky eye placement. The 7mm Delite is a possible option for me, not sure yet because 62 degree is a bit narrow. I mostly use it for planetary with a tracking mount so it may be ok 80% of the time.


Good point about a tracking mount. All of my above praise for the 7mm Delite is with an equatorial mount. Not sure how much I would like it with an alti-azimuth mount. I have a dob but mostly use it with wide field 2 inch eyepieces and only put the Delite in to star test on Polaris.

#15 AxelB

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Posted 25 April 2019 - 08:06 PM

Not mentioned yet but on my watch list: Pentax xw7.

#16 rhcrooks

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Posted 25 April 2019 - 08:59 PM

I have a 100DF. I mounted a Rigel Viewfinder on the Dew Shield and that's my finder - mounting it forward allows you to not have to get so low and crick your neck. Allows me to get close enough to use a 16mm Nagler or 24 Pan to secondary find, and then from there it's usually the 11 T6 or 6.7 ES or Nagler 3-6mm.

 

If you have the DL version then the FOV is narrower...  but at f/7.4  these eyepieces + a Rigel forward-mounted may be all you need. I should mention that I have an affinity for ER of about 10-15mm.


Edited by rhcrooks, 25 April 2019 - 09:01 PM.


#17 Kevin McCarthy

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Posted 26 April 2019 - 01:21 AM

Axel B.

The FOV is less of a concern for me with planetary as my mount tracks. But on the moon getting the the right magnification with the most useful (plus a bit for effect) FOV is something I am keen on. When I use a 9mm delite in the powermate 2.5 I realise the FOV is taking a lot of fun out of viewing the moon. This is probably one situation were my inability to take in the entire FOV has benifits of emersion.Thanks for making remember this I forgot about it and it important for me on the moon.

Kevin

Edited by Kevin McCarthy, 26 April 2019 - 01:23 AM.


#18 Kevin McCarthy

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Posted 27 April 2019 - 07:10 AM

Thanks for your input.

 

Whilst the middle of the table is still open to change. I seem to have settled on a APM 30mm 70deg as my finder EP. compared to the typical 32-34's its a bit less mag. (good for suburban skies) but good true FOV. reviews say it sharp to the edge (my scope is sharp so my EP need to be too right)  good for glasses 22mm also a fair bit cheaper for an EP that might not get used a lot.

 

Kevin.


Edited by Kevin McCarthy, 27 April 2019 - 07:54 AM.

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#19 Starman1

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Posted 27 April 2019 - 10:28 AM

Kevin,

You meant a bit MORE magnification.  Otherwise, you are right on about suburban skies and magnification.


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#20 Kevin McCarthy

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Posted 28 April 2019 - 05:03 PM

Yes yes. A bit more magnification a bit less sky glow.

Realising I wont be able to get by with some of the panoptic shortish eye relife and if I like the sharp 70degree view of this APM then I think I will swap the 18mm delite for the 17mm Delos in my list and then delites 5mm and 3mm. I know there are some nice 3 and 4 mm planetary eyepieces about and with a small exit pupil have noticed little difference with or without glasses. So this might be something to check out.

Thanks all for your comments. I feel I have made two good alterations to my list with the APM and the Ethos.

Regards Kevin

Edited by Kevin McCarthy, 28 April 2019 - 05:04 PM.

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#21 Tyson M

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Posted 28 April 2019 - 07:45 PM

A nice scope like a Tak deserves the best!

 

I love the 17.3 Delos, one of my favorite eyepieces of all time.  The 18.2 Delite is supposed to be up there as well though.

 

You can't go wrong here with whatever direction you choose.  The Delos in the sub 10mm range are 1.1 lbs and longer, so I preferred the Delites with balacing smaller scopes.

 

A 100mm scope can handle the Delos though.



#22 Kevin McCarthy

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Posted 29 April 2019 - 03:26 AM

Tyson.

That's what I have been thinking.
I became aware of a high frequency vibration when using a 9mm delite with a 2.5 powermate in my mount. When I turned the RA drive off the image sharpened noticeably. So things get more critical at high power and below the 17mm ethos I have decided to stick with delites lighter smaller. I have taken my EQ5 of my home made wooden mount its been good for ten years with an WO80FD but its just not stiff enough fir the FC100D at high power and am ordering a Berlebach UNI28. This will hopefully cure the vibrations and portability.

This tripod is the next step after the APM. I have the summer to work through my plans.

Kevin
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