Celestron Regal F-ED65 (1 Viewer)

[henry link]

Steve,

I didn't realize the Edmund printing quality had gotten so bad. I use a Edmund glass slide mostly now (which is perfect through Group 7), but my old Edmund card and chart from 20 years ago are good through about Group 2, so I've never had to use such long distances. I have a 100' set-up marked in my backyard and 10m indoors.

Frank,

I think you'll find all this is fun once you get into it. Besides, these are essential skills if you want to test telescopes.

There is a star-test thread with some photos on the Nikon Subforum now. I made some very poor star-test photos of two Kowa 883's here:

http://birdforum.net/showthread.php?t=125302

Henry

 

[kristoffer]

Thanks Henry! I find these tests very interesting, I like scientifical methods where results can be produces in the same way, quite fast. I will test my swaro scope, I hope it is of poor quality. I really think the image quality is great, but if it can be improved even more i´m the first to be happy :t: (and you will see my scope on the classifieds )

Kristoffer,

Doing a star test is easy. Interpretation is the hard part. There is plenty of information available if you Google "telescope star-test" or something similar. For a quick evaluation of a spotting scope in daylight a reflection of sunlight in a small round shiny object at least 20-30m distant is good enough. As I mentioned before the trim on cars in sunlight has many little star point reflections of the sun. 60x is low for a star test, but enough to reveal the usual problems in birding scopes: astigmatism, pinched optics, coma, poorly made roof prisms and excessive spherical aberration. Often more than one problem is present. Here's a site with a few examples to get you started:

http://www.spacealberta.com/equipment/refractor/startest.htm



Henry

 

[mooreorless]

Hi Henry, I couldn't find online at Edmund Optics the Resolving Power Chart that I bought, but I have a spring 2009 catalog and it has this chart in it. It says maximum resolution is group 3 element 1 and I just looked at it with magnifying glass and these are not useful at all, just blobs. Group 0 down to about 5 is ok and I have used group 1 down to 3 in the past. This chart only costs $18.95 but is a very big target[36"x24"] and is a pain to mount, I used to have it mounted to a piece of plywood. My lens testing kit test charts are good down to group 1 element 6 and it is good. The Edmund glass slide one you are talking about goes for $117. If I remember right Ron[Surveyor] has the the USAF Pattern Wheel Target he uses for his "set up". It goes down to group 7 element 6.
I don't think anybody has talked of moving the charts further out to see how far you can see the smallest element after finding it.
Regards,Steve

 

[FrankD]

Steve,

I found the less ideal of the two samples you sent...but it is still usable. I also did a little google search and found that $117 glass slide that Henry uses. It is a bit out of the range that I am willing to spend.

That $18.95 looks good. I will probably go that route.

Now I just need to find a green laser......

 

[mooreorless]

Frank,

That $18.95 chart is what I cut out that piece you have. A new one might be better, I did notice that this chart will degrade some over time. I left it under my carport for a few days and noticed the humidity degraded it some. Frank if I had one of the better glass charts I would lend it to you. I will no doubt buy one some day, maybe Ebay.
Regards,Steve

 

[FrankD]

I will no doubt buy one some day, maybe Ebay.
Regards,Steve

...already checked....and Amazon too.



I did however find a relatively inexpensive green laser pointer that should be here in time for not only the Regal 80 but also the other scope claiming a Fluorite objective, the Kruger Caldera.

 

[kristoffer]

You said something about this scope might be an equal to the open roof china bins, now I look forward to some testing

I will no doubt buy one some day, maybe Ebay.
Regards,Steve

...already checked....and Amazon too.



I did however find a relatively inexpensive green laser pointer that should be here in time for not only the Regal 80 but also the other scope claiming a Fluorite objective, the Kruger Caldera.

 

[FrankD]

kristoffer,

I have not changed my mind about that statement. The performance level of the scope for the price really is impressive. The optical characteristics that leave an impression and do not need to be measured certainly are obvious with this scope. I would eventually like to find a fixed power semi-wide angle eyepiece that produces the same image quality as the zoom but without the partial obstruction. The Baader Hyperion had slightly less than the Pentax XW but it was still visible in the image. I have a feeling I am going to have consider something between 55-60 degrees in order for it to be eliminated from the image all together.

 

[UTCbirder]

Frank, just a quick question; when you mentioned the hyperion above, did you mean the 21mm? i seem to recall that was the hype you recently purchased, mentioned in another thread. i have a 17 and 13 mm, and was hoping to use those and perhaps due to the larger mag get an unobstructed fov.

just couldnt stand it any longer, and ordered the last 65 that opt had in stock! i never really warmed up to the pentax 65 all that much optically, but the wt and ergos of the scope is first class. i still have all the cartons, plastic, inserts etc so i should be able to get a decent price for the rig.

i decided on the 65 hoping that it won't be too heavy or unwieldly carrying it short to moderate distances in our local patches. for travel i still prefer the little nikon 50.

the 80 was 72oz, which is heavier that the Nikon 82, and that scope becomes a load over the shoulder after awhile. the 65 it looks like is about the same wt as the Nikon at 61oz or so- maybe a bit more than i will want to tote very far but we shall see.

i have the orion edge on ep, 16mm, which is a sweet, dinky piece of glass. nicely made and very sharp over it's 60 degree apov. i'm no expert, to be sure, but one thing that sorta bugs me about this ocular is it seems to have the focal plane at or near the field lens, so that every speck of dust or lint is microscoped into sharp relief at the eyelens end. ugh. i had a dealer tell me "all these modified plossls have the same problem", and if i dont keep the thing scrupulously clean, you can really see it. otherwise it's something i had to learn to ignore. there are some clones of this ep at slightly cheaper prices too, i think. i do plan on trying this one in the 65 Regal scope though for sure.

thanks for your reviews of this spotter, celestron should give you a "bird dog" fee on these scopes!

kind regards to all,
UTC

 

[Can Popper]

You can pm me your address Frank and I can send you a number of narrower field eyepieces to try out. I got a big box full of various eyepieces from Burgess/TMB's to Vixens to Orion/William Optics Planetaries to Edmund RKE's and more. You can mail them back to me when you are done.

 

[FrankD]

Wow CP I am speechless. That is quite an offer. Thank you. I will take you up on it!

UTC,

Yes, it was the 21 mm Hyperion. I had three issues with it specifically. I did see just a bit of the prism edge with it. Noticeably less than the Pentax XW but it was still there. I could probably learn to live with it though.

Two, there were two specs of dirt in it that became annoying when I was scanning large areas of the sky.

Three, it just barely reaches focus for me at infinity. I like to have a little play beyond infinity so this was just mildly annoying.

Please do let us know what you think of the 65. As far as I have been able to discern I am the only one who has genuine experience with it that is posting on the forums.

..as for Celestron hookin' me up...I would have been happy with one of ther 55 degree eyepieces at/around 20 mm.

 

[Can Popper]

I got a plossl 25mm (55 degrees) and Edmund RKE 21mm (45 degrees). I'll be sure to include those.

When I get the address, I'll also send you the following:

Edmund RKE 28mm (45 degrees) - one of my favorite refractor viewing eyepieces
Smart Astronomy Wide 15mm (70 degrees)
Edmund RKE 15mm (45 degrees)
Smart Astronomy Planetary 12.5mm (55 degrees) - also known as the William Optics planetary
Burgess TMB Planetary 9mm (60 degrees)
Vixen NLV Lanthanum 6mm (45 degrees)

Those should more or less test the heck out of your Celestron. The two 15 degree eyepieces, one 45 degrees and the other 70 degrees, should make a really good contrasting pair.

 

[FrankD]

Green Laser test

Henry,

Let me know if this picture is good enough for evaluation. Judging by your earlier comments since I can see the "trail" in both elements then there isn't any Fluorite used in the objective design...yes?

Thanks.

 

[mayoayo]

No,Frank,There is no Fluorite....I was sure that Fluorite is a fancy name for their marketing.As I mentioned before the use of Crystalline Fluorite(as the mineral),can be read as a big Quality control statement in itself,Only reserved to the best
corrected Systems and the fines collimation,Since its relative fragility makes it harder to make lenses out of it,besides of the costly price of the material itself...
I really would like to take a look at the regal,though ,to experience the views.Besides the Extra weight and the inability to properly take advantage of Wide angle Eyepieces,this seems to be a nice ED scope.

 

[FrankD]

Manuel,

I think you are correct in your summary. I have to wonder though if they are then using the FPL-53 mentioned earlier. If it has similar performance to Fluorite then it would explain the performance for the price.

It is funny though...I tested the diminuitive Kruger Optical "Columbia" Malheur 60 mm scope with the laser as well. There was a very thin "trail" in one objective element and next to no trail in the other. I could just barely see it. I will have to take a pic and posted it in the other thread.

 

[henry link]

Good photo, Frank. Yes, it's glass, not Fluorite. As for the Kruger scope, if you see any trail at all, even a very dim one, it's glass.

Henry

 

[FrankD]

Thank you Henry. I assumed as much about the Kruger as well.

For what it is worth though I now have a really cool, green laser pointer to help show my two young boys the night sky. I am sure you know how difficult it can be at times to point out a specific star or other celestial object to a novice....not to mention a child.

So thanks.



Now, I have alot of information to report. I just spent the last hour or so in some wonderfully hot, humid conditions with all of the new eyepieces that I received from Can Popper. I also finally did the requested resolution tests. I have the measurements....now I just need to go back and plug them into the formula.

I am going to just post my observations of the various eyepieces here in this post. I will then try to do the math on the resolution measurements and post that afterwards.

Can Popper sent me 8 eyepieces. I specifically did not look at the field of view specs before making my observations. Here you go:

Edmund Scientific 15 mm
- focuses at Infinity
- low levels of apparent CA
- low levels of noticeable edge distortion
- good apparent sharpness and contrast
- No edge of field cutoff because of the prism

Edmund Scientific 21.5 mm

- focuses at Infinity
- low levels of apparent CA but some noticeable around the edge
- more noticeable field curvature than the 15 mm
- good apparent sharpness and contrast
- a similar 5-10% image cutoff at the bottom of the field of view

Edmunds Scientific 28 mm

- focuses at Infinity
- low levels of apparent CA though some is present around the edges
- less field curvature than the 21 mm and better subsequent edge sharpness
- good apparent sharpness and contrast
- 5% edge cutoff on bottom and left side
- Longest eye relief of any eyepiece I have looked through. Amazing!

Orion 25 mm Plossl

- focuses at Infinity
- Some CA evident around the edges of the image
- low levels of edge distortion
- decent apparent sharpness and constrast
- no image cutoff

SWA 15 mm

- focuses at Infinity
- most noticeable edge distortion
- most CA throughout the field
- 2-3% edge cutoff at the bottom
- good apparent sharpnes
- ok contrast

Burgess 9 mm

- focuses at Infinity
- low levels of edge distortion
- "ok" apparent sharpness and contrast
- some noticeable CA around the edges
- does not lock down in the lock down collar

Smart Astronomy 12.5 mm

- focuses at Infinity
- excellent edge sharpness
- some CA in outer 10-15% of the image
- very good apparent sharpness and contrast
- my favorite of the group

Vixen NLV 6 mm

- focuses at Infinity
- good apparent sharpness and contrast
- good edge sharpness
- slightly more field curvature than Smart Astronomy
- moderate CA in outer 1/3rd of the image
- image still very usable at high magnification (80x) in this scope

All for now. Give me a bit to do the rest of the math.

 

[FrankD]

Ok, you guys can walk me through this or point out what is wrong with my methodology. I set up the USAF resolution target in my backyard exactly 75 feet away from the spot I intended to test. I tested the Celestron 80 mm F-ED at 20x and 80x. I took pictures of the target through the scope with my digital camera. The picture quality is worse than what I see with my eyes but I felt they might serve as a reference/discussion point.

At 20x I was able to resolve group 1, element 1 clearly. I was not able to see the splits between the lines as clearly in group 1, element 2 as clearly so I would assume group 1, element 1 is my limit at 20x at this distance. That group has a measurement value of 2.0 on the chart. There are 900 inches in 75 feet so 900 x 2.0 = 1800. 1800 into 8121 = 4.51 arc seconds.

At 60x I was able to resolve group 1, element 4 clearly. I was not able to do the same with group 1, element 5 so I would assume group 1, element 4 is my limit of resolution for my eyes and this particular scope at 60x. That group has a measurement of 2.83 on the chart. 900 inches times 2.83 = 2547. 2547 divided into 8121 equals 3.188 arc seconds of resolution.

Fill me in on whether or not I did this correctly and/or if there is some error with my setup or measurements.

Thanks.

 

[henry link]

Frank,

Nothing wrong with your math. The 20x result is probably your eyesight acuity. I would measure about that same with any decent scope at 20x (20 x 4.51= 90.2 arcsec, my acuity on a average day).

The 60x result is poor, so something is wrong in the set up (unsteady air?) or the scope. My experience with the USAF target is that optically "perfect" scopes allow me to see resolution equal to about 115/D where D is the aperture in millimeters, so a perfect 80mm scope would show resolution of about 1.44 arcsec. It would be difficult for me to see that at 60x with my acuity (60 x 1.44 = 86.4 arcsec), but I would probably see resolution between 1.5 and 1.6 at 60x if it's there to see. 3.118 arcsec is so poor (250/D) that something must be wrong somewhere. Try your 80x eyepiece and see what that does and make sure there is no hot pavement between the scope and the target (grass is best) and no hot sunlight falling on the scope.

I notice what might be astigmatism in the 60x photo. The horizontal lines of Group 0 appear better resolved than the vertical lines. Curiously the 0 Group vertical lines look better if I zoom into the 20x photo. Do you see that through the eyepiece?

Henry

 

[mooreorless]

Frank, That chart is the better of the two I sent you, it has Gurley of Troy NY on it and is usable down to group 1 element 6. I agree with Henry that something is wrong here. Even if you could see group 1 element 6 at that distance the reading would still only be 2.5 arcsec
Regards,Steve