Explore Scientific ED127 (1 Viewer)

I've had a Canon 100-400mm f/4.5-5.6 for almost 2 years now. I love this lens; it's corner-to-corner sharp when correctly collimated, and the zoom, USM, IS, and ability to take teleconverters make it quite versatile. When stopped down to f/6.3 at full tele, it can take stacked 2x and 1.4x teleconverters and still be sharp. (Note that my copy of this lens is actually 103.7-389mm, not 100-400mm.)

But I wanted more aperture. With teleconverters on, the 100-400mm becomes too slow to get low ISOs and fast shutter speeds on moving subjects; also it doesn't quite have enough diffraction-limited resolving power to take full advantage of good seeing (low atmospheric thermal distortion) when photographing distant subjects such as nests and aeries.

The supertelephoto lenses are far too expensive. The only remaining choice was a telescope. I eliminated reflectors as a choice long ago, because although cheaper for the same aperture, they give donut-shaped bokeh and are either too slow (e.g. f/10 catadioptrics) or are hard to use for daytime eyepiece viewing and straight-through sighting. That left apochromatic refractors as the only choice.

Finally I took the plunge and decided on the Explore Scientific 127mm f/7.5 triplet. It's very heavy, but has comparable aperture to a Canon 600mm f/4 for high-power use (the 600mm is actually just 585mm, and needs to be stopped down to f/4.5 or f/5 for good sharpness especially with stacked teleconverters); I was sick of 500 and 600mm f/4 envy, so I wanted a telescope that could match one at least in useful aperture and resolving power, if not autofocus, image stabilization and ease of portability.

The ES127 is 952.5mm f/7.5 and weighs 17.8 pounds without a camera or eyepiece attached (but with dew shield / hood). It's an effort to carry it around, but it can be done and I have been doing it.

Sharpness is excellent. There's a touch of violet-fringe CA that can only be seen against very sharp contrasts (and becomes more apparent with teleconverters attached). At 952mm it can often crop all but the smallest birds, so I bought the Televue 0.8x Reducer/Flattener for 800-1000mm telescopes (RFL-4087). This works quite well, and turns the scope into a 756mm f/6. I have often put a 2x teleconverter on my 100-400mm for tripod use, which makes that lens effectively 775mm — so this is a focal length that's already familiar to me (albeit with the ability to zoom out to 207mm, which I don't have on the telescope).

The ED127's dual-speed (7.7:1) Crayford focuser is a joy to use. It's the best manual focusing experience I've ever had. However one big problem I've been having with the ED127 is getting extension tubes and other 2" components to tighten parallel to the focal plane; the ED127's focuser has its brass ring in a nonstandard position. I've given my thumb a callus from repeated tightening of thumbscrews! I've managed to reduce the problem quite a bit by using a 2" Parfocalizing Ring.

Despite being designed for astronomy, the ES127 performs great at close focusing! I tried stacking extension tubes to test out its capabilities. I haven't yet taken this scope far from home, and I've only had it for 2 weeks so far; I've been using much of that time to test the technical capabilities of the scope and figuring out how best to use it. So I don't yet have a lot of shots that I feel are perfect for showing off the scope. However, here is a photograph of a juvenile House Sparrow on my balcony, at about 5.4 meters distance; I used the RFL-4087 and Canon 40D for this shot.

To show both overall image quality and fine pixel detail, I'm posting three different crops. The first one is only cropped horizontally, not vertically. The second is a 66.7% crop, and the third is a 100% crop.


Has anyone else used a 120+ mm refractor for bird photography?

I'm interested in replacing the dew shield with a lightweight hood, perhaps Kydex as one person recommended in a review of the ED127, but I'm not sure how to go about this and would appreciate advice. I would also appreciate advice on how best to build or procure an aperture limiter, for stopping down a refractor (to get more depth of field and less chromatic aberration).

I can't help but think that the f/5.95 with ES127 + RFL-4087 is probably enough for a xxD / xxxD body to give reliable focus confirmation. Unfortunately it would be necessary either to hack together some electronics to trick the camera into doing this, or to hack the firmware to accomplish the same thing.

The lack of electronics in the EOS bayonet adapter results in some odd behavior by my 450D and 40D. Both cameras show incorrect Live View exposure preview. The 40D's problem is much worse. The 450D can be cured by attaching it to a real EF or EF-S lens after being turned on (and turning off auto power down so this doesn't have to be done repeatedly) before moving it onto the telescope. However this doesn't fix the problem on the 40D, and the 40D's exposure preview offset is not even constant. The other problem is that trying to shoot a picture with an EF teleconverter attached to the scope results in an error message, unless I tape the contacts on the closest teleconverter. Has anyone else had these problems?

Hi David,

Thanks for your great report on the 127mm scope.

Should be able to help with a few points.

I think any teleconverter that has electronic contacts has to be taped up to stop the error problems. I use a Kenko Pro 1.4X and they have the same problem. I leave tape on mine all the time as I only use it on my scope. I keep a couple of spare bits of tape stuck to the bottom of the camera just in case I need them.

You can buy the focus confirm chips on ebay and these can be glued into the adapter that mates to the camera. That should give you focus confirmation at f5.95 and possibly f7.5 too.

For the aperture limiter you could find a plastic lid of the right diameter that was a snug fit in the front of the dew shield. Cut a hole in it and spray it matt black. My Skywatcher is supplied with one that has a 50mm hole in the front of it plus I've made an insert to fit in the hole to take it to 25mm. It gives a big increase to depth of field and alters the bokeh totally. It can be handy at very close ranges as you get a much more useful depth of field. Depth of field becomes very shallow at close range as you can see in your sparrow photo.

With regards to the violet CA, the scope uses Hoya FCD1 ED in the third correcting element and this is the equivalent of FPL-51. This glass is known to produce a little CA but this only really shows up in photography and probably isn't even detectable in visual use. The other two elements are usually selected to be a good match for the third ED element.

Since I've had my Skywatcher 600mm 80ED I've not been tempted to go bigger. Main reason is it's light enough to be portable and I've carried it around for 4 hours some days and most of that was walking, just setting the scope down to take a photo and then walking again. With a bigger heavier scope I'd probably have to make some sort of backpack that the scope could strap into. Photos with my Skywatcher Pro 80ED are colour free so I'd probably go for the Skywatcher Pro 120ED if I were to get another. It uses the same glass so I'd know what to expect. My 600mm with a Kenko 1.4X (840mm) is usually enough and I have a 2.3X barlow for when I need to go longer.

I get the same problem with my 450D in Liveview, the image is very dark. I rarely use Liveview but I'll remember your tip about putting a lens on first.

The dew shield should be easy to remove, are their any little screws or anything to loosen off. Then you could look at the design and see about making a different one. Once it's removed you should see some small screws in the lens cell and these can be adjusted to alter the collimation. Only look into doing this if you think the glass has moved. You can get special eyepieces to check the collimation.

Look forward to more photos.

Paul.

Hi Paul!

Thanks for the tip about focus confirmation chips. I see two items currently on ebay, "Nikon to Canon EOS Adapter with Focus AF Confirmation" and "For M42 to Canon EOS Adapter with Focus AF Confirmation". It's unclear to me whether the chip can be detached from either of these and glued to the 2" to Canon EOS adapter I'm using on the scope. Have you used something like this yourself? I wonder if it would fix the dark Live View problem.

The dew shield is pretty easy to remove, but my main issue is that I don't know how to work with Kydex. I'm not sure how to go about shaping it; if I wrap it around the dew shield, it'll have slightly too large a diameter.

In all the reviews I've read comparing the Skywatcher 120ED or Orion EON 120 ED against the Explore Scientific ED127, the two were reported to have equal levels of chromatic aberration, but the ED127 was reported to have slightly better image quality. These were visual reviews, so I figured that if there was any noticeable visual difference, it would be a larger difference photographically. That and the build quality, and user collimation, is why I chose the ES ED127.

Regarding stopping down the aperture... I'd really like to stop it down flush with the lens, instead of at the end of the dew shield; I think that would do a better job of reducing CA and improving sharpness. OTOH, doing it at the end of the dew shield would be much easier, and would probably result in softer background bokeh (which would be good) — is this what you have experienced? Wide open, the ED127 gives soft foreground bokeh but hard background bokeh. The fg bokeh has bluish fringing while the bg bokeh has yellow fringing.

My dream is to rig an iris diaphragm flush against the lens, with a lightweight hood hanging off the end of it.


Some more photos...

1. Red-throated Loon in partial molt into breeding plumage; pure prime focus, 53.6% resized crop
2. Common Raven nest with two chicks, one sleeping, one awake (one had already left the nest); 2x teleconverter used, no crop; to see into nest at this good angle, I was about 410 feet away
3. Common Raven nest with parent visiting and one chick begging; 2x teleconverter used, no crop
4. fledgling Common Raven, fresh out of the nest; pure prime focus, 66.7% resized crop (had to use more noise reduction than I would've liked, to get it under the 400 kB limit)
5. juvenile Great Blue Heron with fish; RFL-4087 used, 50% resized crop

1. 100% crop from the Great Blue Heron photo in previous post (not too much detail on the heron due to motion blur, but the fish is sharp)
2. Peregrine Falcon; pure prime focus, no crop
3. Photo #2, 66.7% resized crop
4. Sanderling in (almost?) full breeding plumage... these were very hard to focus at such close range and narrow depth of field, as they move so fast! Pure prime focus, 50% resized crop.

I'm starting to realize that the RFL-4087 might be significantly degrading sharpness... photos still have an overall sharp look, but there seems to be not enough detail that any would be lost in a 66.7% resize. Haven't gotten around to doing a formal test of that yet.

On ebay, type in 'Canon af confirm chip' and you should get plenty of results for just the chip on its own.

Focal reducers and field flatteners tend to work best when they are designed specifically to match to the scope. The universal ones do an ok job but they will vary in image quality depending on the scopes aperture, the shape of the glass, its focal length and all the other variables.

That iris diaphragm looks sweet, something like that on the scope would be handy.

All your images are turning out nicely.

I'll post up some barlow/teleconverter edge sharpness images in the other thread later today or maybe tomorrow.

Paul.

Paul Corfield said:

On ebay, type in 'Canon af confirm chip' and you should get plenty of results for just the chip on its own.

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Thanks! That turns up a ton of results. Some of them are apparently even programmable, which is unbelievably awesome.

I'm very curious as to how this chip will affect other aspects of operation. My expectation is that it will get rid of the dark Live View bug, and the error message when using an un-taped-pin teleconverter... but you have both of those problems, so is that because you don't use an AF confirm chip?



Tonight I made myself an artificial star by poking a pinprick hole in aluminum foil and wrapping it around a "full spectrum" fluorescent light bulb, and collimated my ED127. I managed to fix the annoyingly asymmetrical violet fringe: (attached photo — left=before, right=after)

Interestingly, every time I put my hand near the objective lens (to adjust a collimation screw), and went back to look at the Live View, the defocused artificial star had very visible heat waves in front if it — from the heat of my hands!

I wish I knew what wavelength range the fringe is chiefly comprised of. Then I could buy an appropriate 2" diameter longpass filter and remove most of the fringe without having to stop down the aperture. (I expect the resulting yellow cast would be easy enough to compensate for in most cases with white balance. Though in some cases a bird might have pretty violet coloring, in which case the filter would ruin it.)

During this experiment I also compared the RFL-4087 against pure prime focus on the artificial star, and the RFL-4087 came up very favorably; it's sharper than pure prime focus. So probably my RFL-4087 shots today were soft because of bad seeing, not problems with my equipment. I kept the RFL-4087 on the whole time, so there's nothing to compare against. (I used a tripod+bipod setup for ultra steady shooting, and bracketed my manual focus, so bad seeing is the only thing left.)


Edit: I've done some tests photographing a book cover (filling the frame) with different lenses: Canon 100mm Macro; Canon 100-400mm @ 400mm — plain, with Canon 1.4x II, and with Canon 2x II; ED127 + RFL-4087; and ED127 prime. In each case, I did the full progression starting from wide open and stopping down (except on the ED127 of course).

I've verified that the ED127 + RFL-4087 combo is very sharp, and remarkably free of chromatic aberration (I can't see any extra CA in the edges/corners at all). It makes me see how much chromatic aberration the Canon teleconverters have on the edges... the ED127 + RFL-4087 is optically in every way superior to the 100-400mm @ 400mm + Canon 2x II, and has much more magnification at close range (but very similar magnification at infinity), because the 100-400mm decreases its focal length as you focus closer.

The RFL-4087 doing a very good job of correcting flatness, too. At the same subject distance (of a flat subject), the ED127 + RFL-4087 is sharper on the edges than the ED127 prime, even if cropped down to match the ED127 prime photo.

I'd love to see what the ED127 + RFL-4087 looks like on a full-frame DSLR!

In case anyone is interested, here're some of the comparison shots I did a few days ago.

The 100mm USM Macro is one of Canon's sharpest lens, and is the sharpest lens I own, so I used that as my baseline.

Unfortunately in this test run I did not match the image area as perfectly as I'd like, and I also did not match the lighting perfectly (the sun moved as I progressed through this test), and didn't match the axis perfectly either, so I'll probably repeat the test another time, probably at night with artificial lighting.

1. Canon 100mm USM Macro at f/5.6, 98.90 mm focal length at infinity (unmeasured at subject distance used in this test)
2. Explore Scientific 127mm triplet + Televue RFL-4087 0.8x Reducer/Flattener, 756 mm focal length at infinity; distance to subject, 289 inches
3. Explore Scientific 127mm triplet at prime focus, 952.5 mm focal length at infinity; distance to subject, 355 inches (this photo not shown here; uploaded at full resolution, linked below)

The width of the area of the book cover used for this test is about 7¼ inches.

The differences I notice between the two lenses are:

1. Slightly more softness in the telescope; not enough to hide fine detail
2. Diffuse softness in the blue channel in the telescope (probably from uncorrected spectral violet)
3. Slight vignetting from ED127 + RFL-4087
4. Very, very slight barrel distortion (on the order of 1 pixel at the edges) from the RFL-4087

Also, the ED127 at prime focus shows significant softness towards the edges, which the RFL-4087 apparently corrects nicely.

<<Download full res photos here>> (use Download button)

Photos are sharpened equally.

The fact that it holds up that well vs. the venerable 100mm USM Macro is a testament to the sharpness of this scope. Bet it does wonders on the lunar surface too. Thank you for the test.

I think I've found a way to make Live View work properly without having to put a lens on the camera first. On my Canon 450D I found that switching from 'M' to 'Av' gave a bright image in Live View. Do the focusing and then switch back to 'M' to set the shutter speed and take the photo.

Paul.

Fowl Mouth said:

The fact that it holds up that well vs. the venerable 100mm USM Macro is a testament to the sharpness of this scope. Bet it does wonders on the lunar surface too. Thank you for the test.

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You're welcome... and I'll bet it does! But I've had a bunch of cloudy nights in a row.

Paul Corfield said:

I think I've found a way to make Live View work properly without having to put a lens on the camera first. On my Canon 450D I found that switching from 'M' to 'Av' gave a bright image in Live View. Do the focusing and then switch back to 'M' to set the shutter speed and take the photo.

Click to expand...

That works on the 40D too, and in fact on the 40D you can also turn off the custom function "Live View exposure simulation" and not even have to switch between 'M' and 'A'.

But I like to adjust my exposure in 'M' mode using Live View as a guide (without having to take test shots)... and sometimes I like to take shots in Live View.



A correction (since I can no longer edit the post):

David Ellsworth said:

Also, the ED127 at prime focus shows significant softness towards the edges, which the RFL-4087 apparently corrects nicely.

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Actually I notice that the lower-left edges/corner are asymmetrically softened in the prime shot, however, the lower-right and upper-right are sharper. I blame this partially on my failure to match the camera axis between lenses and maybe will get to the bottom of it when I repeat the test.

Compared against Canon 600mm f/4

This afternoon a fellow photographer let me use his Canon 600mm f/4 to take some test shots, so I could compare it in image quality against my Explore Scientific ED127. In case you want to skip the rest — the ED127 won! In terms of fine detail sharpness, they seemed to be equally good, but the ED127 had less overall haze (resulting in better contrast). However, this test was done in the late afternoon, with yellowish sunlight. With light containing more violet the ED127 might not fare as well.


I put a Canon 1.4x II teleconverter on the 600mm, and put my Televue RFL-4087 on the ED127. This brought them to very close focal lengths — 952.5mm*0.793 = 755mm for the ED127, and 580mm*1.393=808mm for the Canon 600mm. (Yes, this Canon 600mm is actually 580mm, not 600mm. Whereas the ED127 really is 952.5mm.)

With the 600mm stopped down to f/4.5, for an effective f/6.3 with the teleconverter, it had 580mm/4.5 = 129mm effective aperture. This brought it very close to the ED127's aperture of 127mm.

I took 10 shots with the ED127 and 18 shots with the Canon 600mm, so I could select the frames with the best "seeing". (As I used a distant subject for testing, imperfect atmospheric conditions had an effect.)

The ED127 won; it had more overall contrast (this may just be due to the ED127 having a longer default hood, and/or the 600mm having more dust build-up on the front element, but may also have to do with the ED127 having fewer elements). Fine contrast may be better on the ED127, but I'm less sure of this as I may have gotten lucky seeing with the ED127 (despite taking multiple shots). If the 600mm wins in violet focus, this test might not show it due to the yellowish late-afternoon sunlight (the sun was about 14.5 degrees in altitude); as far as I can tell given this test's results, the ED127 either wins or breaks even in terms of blue channel focus. This was a quick test, and atmospheric conditions were imperfect, and I didn't painstakingly ensure that focus was exactly the same between the two lenses, so I wouldn't take it as absolutely conclusive — but I'm pretty sure a more controlled test would give the same result.

Of course, the Canon 600mm is capable of being used as a 580mm lens, while the ED127 can only be reduced to 755mm (unless there's a good 0.6x reducer that I'm unaware of). And obviously the 600mm has autofocus and image stabilization, and is lighter in weight. OTOH, manual focus is much easier on the ED127 with its dual-speed Crayford focuser. But the 600mm can focus as close as 5.5 meters without extension tubes, and while I haven't measured the ED127's close focus yet, the lens equation says it should be about 9 meters (with 11 cm of backfocus).

I did not have a flat subject, so I could not quickly compare field flatness between the two lenses. I did not want to take too much time using this photographer's lens as, although the bird activity was at a lull, action could have happened at any time (and did happen, 8 minutes after I completed the test).

If anyone wants to see the test shots, I'll post them on request.

Incidentally, I expect that with the ED127 vs the Canon 800mm f/5.6, the latter would win. I'm curious as to whether the Sigmonster 300-800mm f/5.6 would win as well.


As for the bird photos taken during this session, they were flight shots, and none of the really interesting ones came out in focus. (Plenty came out in focus, just not the most interesting/well-composed/close ones.) But I must say, I like the narrow depth of field this lens (telescope) gives.

David, this is a highly useful comparo, even if it wasn't "overly" scientific. Casual but well thought out tests often give the most honest real world results, IMO. Either you need to stop bragging about this scope, or I need to stop visiting this forum...you're making me want one. FWIW, I'd love to see some results of similar shots from each setup, but no hurry.

Fowl Mouth said:

David, this is a highly useful comparo, even if it wasn't "overly" scientific. Casual but well thought out tests often give the most honest real world results, IMO. Either you need to stop bragging about this scope, or I need to stop visiting this forum...you're making me want one.

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Glad you found this interesting. I think a really useful comparison would be ES ED127 versus Skywatcher 120ED or Orion EON 120ED. Not too far apart in price or aperture, but one is much lighter in weight! It's a shame the 120ED isn't user-collimatable, but perhaps a doublet doesn't need collimation as much as a triplet. I wish my camera lenses were user-collimatable, even the wide zoom.

Fowl Mouth said:

FWIW, I'd love to see some results of similar shots from each setup, but no hurry.

Click to expand...

<<full-resolution comparison photos added here>> (use Download button)

Processed identically, except that the 600mm photo was given +0.15 extra EV compensation in the RAW conversion to match the exposure of the ED127 shot, and the 600mm photo was sharpened with strength 321, radius 0.3 while the ED127 shot was sharpened with strength 300, radius 0.3 (an attempt to compensate for the extra magnification in the 600mm shot).

Really, this test was far too casual... I focused the 600mm+1.4x using autofocus, then took 3 shots at f/6.3... then I readjusted the focus, thinking manual focus with Live View was bound to give an improvement. It turns out the readjusted focus was worse. So with 10 shots, the ED127 had more of a chance to get good seeing. However, haze was not affected by seeing; only fine detail was affected.

I used to post on a bird photography website that was mostly frequented by users with big Canon lenses. They were always amazed at how my 600mm Skywatcher 80ED was more than a match for their mega buck Canon 600mm lenses.

Paul.

David Ellsworth said:

Glad you found this interesting. I think a really useful comparison would be ES ED127 versus Skywatcher 120ED or Orion EON 120ED. Not too far apart in price or aperture, but one is much lighter in weight! It's a shame the 120ED isn't user-collimatable, but perhaps a doublet doesn't need collimation as much as a triplet. I wish my camera lenses were user-collimatable, even the wide zoom.

Click to expand...

The Skywatcher/Orion/Celestron Synta made scopes are collimated at the factory and I think due to the construction, there's nothing that can move after that. I've dropped mine twice onto hard ground, once it fell off the tripod where I didn't clip the plate in properly and the other time the tripod blew over. Collimation hasn't been affected.

I saw a comparison the other day between the Orion 120ED and the 127ED clones and they gave the 120ED the edge in the overall result, that was probably because image quality was pretty much identical put price difference would give the 120ED the edge. For a doublet the FPL-53 Synta scopes are amazing performers for the price. It's only when you start getting into Takahashi territory that you start to see a difference.

Paul.

Admittedly, the Eon 120 has been an item of interest to me lately, and i would be lying if I said the price wasn't a factor.

Thanks for the image posts, David. There's no notable IQ difference between the ES-127+TV vs. the 600+1.4, IMO. I can see where the two are focused on slightly different shingles (?), but where they are focused they appear equally as sharp to my eyes. That is to say "wow" for the ES. Although I'd love autofocus, it's much harder to just throw the 600 1:4 on a GEM and slide a 3-6 Nagler Zoom into the back end. This idea is getting more tempting. I see this as a perfect match for an Oly E-30, with its built in Stabilization and 2x crop factor...

Paul Corfield said:

The Skywatcher/Orion/Celestron Synta made scopes are collimated at the factory and I think due to the construction, there's nothing that can move after that. I've dropped mine twice onto hard ground, once it fell off the tripod where I didn't clip the plate in properly and the other time the tripod blew over. Collimation hasn't been affected.

Click to expand...

That's impressive. Though it's probably much easier to collimate an 80mm lens (permanently) than a 120mm lens.

You must have been scared, though! I've dropped lenses more often than I'd like to admit... they rarely come out of it the same as they were before.

Paul Corfield said:

I saw a comparison the other day between the Orion 120ED and the 127ED clones and they gave the 120ED the edge in the overall result, that was probably because image quality was pretty much identical put price difference would give the 120ED the edge. For a doublet the FPL-53 Synta scopes are amazing performers for the price. It's only when you start getting into Takahashi territory that you start to see a difference.

Click to expand...

Could you please point me to that 120ED vs ED127 comparison? I would like lighter weight, if I didn't lose anything in image quality or near-focus ability. The ES ED127's focuser has 109mm of travel; I'm not sure about the 120EDs'.

The only budget 127mm APOs are the Explore Scientific and Meade, right? Has it been established whether these are clones or have significant differences? None of the web sites I've found of places that sell the Meade even have the correct photo (they show a photo of a much shorter scope).

Fowl Mouth said:

Thanks for the image posts, David. There's no notable IQ difference between the ES-127+TV vs. the 600+1.4, IMO.

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There is a significant difference; it's in the amount of stray light (flat greyness) added to the entire photo, by diffusion of light. This is for the same reason that if you shine a laser through glass, you see a dot on the air/glass interfaces (and a line going through the glass, much darker than the dots). The 600+1.4 has more of this, making it slightly worse than the ES-127+TV. You can easily subtract the greyness during raw conversion or postprocessing, however it has the effect of increasing noise. I can even see more noise in the 600+1.4 photo, in the shady areas.

Fowl Mouth said:

I can see where the two are focused on slightly different shingles (?), but where they are focused they appear equally as sharp to my eyes.

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That's mostly atmospheric distortion, which changes moment to moment. If I had taken 10 or more shots with the 600+1.4, I probably would've gotten a luckier one with lower distortion.

I think the 600+1.4 has better field flatness, but it's hard to tell with a non-flat subject and imperfect atmospheric conditions.

Fowl Mouth said:

That is to say "wow" for the ES. Although I'd love autofocus, it's much harder to just throw the 600 1:4 on a GEM and slide a 3-6 Nagler Zoom into the back end.

Click to expand...

I made an erecting eyepiece for my 100-400mm a while back. I pirated the roof prism from an 8x32 Kenko monocular, the front element group from an Orion 9mm Expanse eyepiece (which was about 16-17mm), carved a hole into a Canon rear cap, and glued the three parts together (after adjusting the eyepiece to proper focal plane by sliding it through the hole in the rear cap).

It was pretty nice to be able to have a 25x70 monocular in a pinch without having to carry anything extra. I also had a chance to try my eyepiece on a Canon 500mm f/4, and it looked good on that, too.

Unfortunately I dropped the eyepiece next to a lake and the prism rolled in. That prism was exactly the perfect size and its mounting worked for me... I have no idea how to get one again without buying a whole monocular.

The eyepiece wasn't perfect; it didn't present a flat field. It was also focused precisely on the rear surface of the prism, which meant I had to keep the prism immaculate; any dust would be focused sharply in the field of view. But, it was nice and bright and contrasty, and sharp in a pretty good region around the center.

There aren't many (or any?) good eyepieces available that don't require the focal plane to be deep inside them, and the roof prism I used left very little path length free to the eyepiece.

So yes — it's really nice to have something that can take any eyepiece and any prism or diagonal you want! (well, any, as long as it fits a 2" or 1.25" tube)

From what I read it's the fact that it's a triplet that collimation is needed.

A review here of the ES127 against the 120ED

This review here compares the Orion 120ED against the Astro Tech 127EDT which is a similar scope to the ES127. The Astro Tech, Meade, Maxvision and others use the FPL51 apo triplet made by Kunming Optical. The Explore Scientific uses Hoya's version of FPL51 which they brand as FCD1 but the characteristics for both are the same according to owners.

This scope here in the UK is the Maxvision, a clone 127ED

Another name it went by was the North Group 127ED but not sure if that one is still made.

Paul.

Thanks for this information, Paul.

Paul Corfield said:

A review here of the ES127 against the 120ED

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I read the same review. There are two sentences... "Maybe the extra 7mm of aperture, but though both scopes easily showed the shadow of the rings on the disk of the planet, the ES scope made me feel it was more 3 dimensional." And, "Optically it was much harder to find a clear cut winner, but again, an edge to the ES 127." It's a visual review; I figured that for imaging, this smaller perceived visual difference would translate into a larger difference in image quality.

Paul Corfield said:

This review here compares the Orion 120ED against the Astro Tech 127EDT which is a similar scope to the ES127. The Astro Tech, Meade, Maxvision and others use the FPL51 apo triplet made by Kunming Optical. The Explore Scientific uses Hoya's version of FPL51 which they brand as FCD1 but the characteristics for both are the same according to owners.

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I seem to remember maybe reading this review, but it's another visual review and it's about a different 127 triplet, so maybe at the time I didn't give it much pertinence. However, now I see that it might indeed be pertinent... Kunming Optical appears to be the manufacturer even of the Explore Scientific triplet. On the other hand, I have the impression that Explore Scientific has better quality control.

Paul Corfield said:

This scope here in the UK is the Maxvision, a clone 127ED

Another name it went by was the North Group 127ED but not sure if that one is still made.

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Wow, that indeed looks exactly like the Explore Scientific. And it costs less. But maybe that lower cost is a result of less quality control.


I think that there just can't be any substitute for a direct comparison under otherwise identical conditions, with the same camera. But I'm now at the 29 day mark, so no returning the ES-127 anymore... maybe I can find somebody in my neighborhood who owns a 120ED...

When I decided on the ES-127, I thought I could handle the weight, but it's really hard to carry this thing comfortably for long distances (and I go birding mainly on foot). But maybe I can partially solve that problem by using a home-made hood instead of the supplied dew shield.

David Ellsworth said:

There is a significant difference; it's in the amount of stray light (flat greyness) added to the entire photo, by diffusion of light. This is for the same reason that if you shine a laser through glass, you see a dot on the air/glass interfaces (and a line going through the glass, much darker than the dots). The 600+1.4 has more of this, making it slightly worse than the ES-127+TV. You can easily subtract the greyness during raw conversion or postprocessing, however it has the effect of increasing noise. I can even see more noise in the 600+1.4 photo, in the shady areas.

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I should step back with my statement, since your point has validity. I was honestly only looking at the comparison of sharpness and CA control, both of which look awesome. The "greyness" is something I understand as a product of more elements in the 600, equaling increased scatter, even if the Canon does use superb glass. Looking back at the images I see the obvious difference.



On a side note, regarding Kunming Optical, they are one of the leaders in quality products coming out of China these days. I have a Garret Optical 15x85 HD WP made by Kunming. Awesome binoculars in every way, especially for the price.