Various eyepiece review with PF-100ED (1 Viewer)

The thought has occured to me, that's why I started the post out with "Just for grins".

In reality, the only things worth seeing with the 2.3 lanthanum are the stars and planets that it was made to see. Don't have to worry about any depth of field with those subjects.

Maybe I'll try the 2.3mm on some subject really far away terrestrially. That would help eliminate the depth of field problem. However, atmospheric attenuation and distortion would come into play big time.

*EDIT* I found the following sign that is more on a single focal plane. Distance to it is about 150 yards. Picture taken with Lanthanum 2.3mm using no camera zoom. Sign is about the size of the "For Rent" or "For Sale" signs that are standard in the US. Notice how the fine print is readable even at this range and magnification.

Also included a picture of the coupling on an utility pole located 75 yards away.

The most useful target for us to evaluate the scope's optics from your photos would be a standard resolution chart like the USAF 1951 Resolution Test Pattern, available in various forms at www.edmundoptics.com. No problems with DOF and it could be placed close enough to avoid air turbulance.

I'll be shooting some targets at 300 yards this Memorial Day weekend so I will take a few pictures using the 2.3mm lanthanum. The flat paper targets and the straight grid lines should allow a better focus for the 2.3 lanthanums.

Hopefully my Siebert OCA will be here by then so I can include some shots from the binoviewer.

Now let's see some birds, or bird.

Had a real cooperative bird today along with some decent light. Here are two pics I took using the Pentax SMC zoom.

Can
Finally got the chance to try the 32mm Plossl with my PF65ED today on some real birds. I've gone for the Baader 6030 adapter to connect my Casio P600 to the scope. Even with the excellent eye relief on the lens, the camera still has to be zoomed to max optical zoom (4 x) to eliminate vignetting. So it's never going to be an ideal set up. What is a plus is the remote that comes with the Casio, so handshake is not an issue and no faffing around with remote releases.

Attached is the best of the bunch, which I'm pleased with. Focussing seems to be the critical issue, with very little depth of field to play with.

John

John Fleet said:

Can


Attached is the best of the bunch, which I'm pleased with. Focussing seems to be the critical issue, with very little depth of field to play with.

John

Click to expand...

Looks like a great photo to me.
Brian.

That's a darn fine photo. Puts most of mine to shame...LOL Looks like the digiscoping adapter makes a big difference in bringing out the finest detail. After my wife saw your picture, I finally got approval to buy one...thanks!

When you say you still get vignetting, are you referring to the dark areas around the circle of the image, like the no camera zoom pictures I took with my narrower field eyepieces? If yes, that you need to try a long eyerelief, super widefield eyepiece next.

Well, I just got back from the gun range. I took a bunch of pictures with the Orion Stratus 5mm, Orion Lanthanum 2.3mm, GSO Superview 10mm, and my new Siebert Ultra 24mm.

My OCA from Siebert Optics did come in at last. Unfortunately, one of the lenses was wrong so I had to send it back to Siebert for retrofitting. Thus no binoviewer report with the Pentax.

I shot the 300 yards range at the gun range. The weather condition was patchy clouds with occasional rain and occasional sun. When the sun came out, I experienced some bad mirage. When the clouds covered the sun, the mirage lessened greatly. Wind was blowing the whole time and my cheap eBay tripod that held my Pentax shook so I wasn't able to get perfect photos.

That said, when the mirage was gone, I could see my ragged bullet holes on the paper at 300 yards and on other people's targets at 400 yards. I could even see the bullet holes that fell onto the white target paper. They may not be readily apparent on my enclosed pictures due to wind shake (and picture down sampling).

Overall, I am very pleased though I'll be buying a new tripod, LOL. I could see where my shots was being placed and didn't have to walk or drive down range like the other fellows to see how I was doing.

And pictures taken with the Siebert Ultra 24mm...


You will notice that the GSO Superview had a sharp image in the center but fuzzier images out towards the edge. It appears the F/6.3 of the Pentax 100ED is too fast for this eyepiece. On the other 3 $100+ eyepieces, we do not see this effect.

On another note, I did get to test my binoviewer with my eBay Maksutov scope. It came to focus on the slow F/13.3 optical system of that scope. Although the scope itself lacks the contrast of the Pentax (no where close), the effect was still delightful. I can only imagine the joy of using it on the Pentax.

Soon...soon...

Siebert 24mm Ultra

One of the most unusual eyepiece in Harry Siebert's eyepiece offerings is the Siebert 24mm Ultra.

What makes it different from other eyepieces is that it offers a wide field of view (65 degrees), long eyerelief (20mm), and a flat field by using only 3 lenses.

Those who are familiar with eyepieces know that on the surface, having such a combination of features seems to be mutually exclusive. Other 3 lens eyepiece designs such as the Kellner or Edmund RKE have narrow fields of 35 to 45 degrees. Typically, most of today's eyepieces use 5, 6, or 7 lenses to provide the three features in the same eyepiece. However, using so many lenses has its own drawbacks, namely the loss of light and contrast.

In a test done by Cloudy Nights (http://www.cloudynights.com/documents/planetaryeyepieces.pdf), the three to four element eyepieces ruled the field over the fancier, more expensive eyepieces (such as the Televue Panoptic and Pentax) when it came to unveiling the fine details of planets.

Recently I was in the market for an eyepiece that would provide the lowest magnification and the widest field of view on my Pentax 100ED. Such an eyepiece would be useful for digiscoping because I wouldn't need to use as much camera zoom and it would result in fast shutter speeds due to its large exit pupil. Doing some research on Cloudy Nights, Televue's website, and Harry Siebert's website, I found that for the 1.25 inch eyepieces, 24mm was the lowest power one can go and still have a field of view in the mid 60's and higher. Beyond 24mm, one starts to trade field of view for a lower magnification due to the limitation of the 1.25 inch barrel size.

The two widest field 24mm eyepieces are the Televue Panoptic 24mm and the Siebert 24mm Ultra. On the Siebert website, some comparisons were made between the Siebert 24mm and the Panoptic 24mm (http://www.siebertoptics.com/SiebertOptics-eyepiececomparisons.html#24mm compare). The Siebert 24mm seems to compare well with the Pano at F6 or above which is where the Pentax spotters are. Reading Siebert's findings and knowing the result of the Cloudy Night review, I decided to go with the Siebert Ultra.

First, I called up Harry and asked him what his secret sauce was out of curiosity. I asked Harry if he used fancy glass elements made of lanthanum or flourite to achieve the same features of the Panoptic with half the glass. Harry laughed and told me that wasn't the case. He achieved the features through the clever design trick of moving the chromatic aberration to the edge. I could tell from the tone of Harry's voice that he was proud of his 24mm Ultra eyepieces.

From the five attached pictures below, one can see that the Ultra 24mm provides wide, sharp, and flat views. And if one looks closely at the image edge, one can also see the chromatic aberration that Harry Siebert intentionally moved to achieve the three features using only 3 lenses.

40mm Plossl

I went out to the gun ranges again to try out my universal digiscoping adapter. The eyepiece I used on it was the 40mm Plossl and the Pentax SMC zoom (24mm to 8mm version).

The 40mm Plossl, as usual, took wonderful pictures. I think it is the most goof proof digiscoping eyepiece around. I also took pictures through my SMC zoom. The zoom provides good images and great color but it has a big drawback. When I change the magnification on the zoom, the eyerelief changes and I need to readjust the position of my camera on the digiscoping adapter. A great annoyance. Zoom my Fuji F10, however, does not require a readjustment of the camera's position.

Below I am posting three pictures. One is of the targets shot through the SMC zoom at 24mm. The second is of the targets through the 40mm plossl with no camera zoom. The third is of the targets through the 40mm plossl with 3x camera zoom.

The photos turn out to be quite revealing. If you compare the two no camera zoom photos of the SMC at 24mm and the 40mm plossl, you will see apparent field of views appear to be identical. However, the 40mm plossl has a much larger true field of view, just look at the great area you can see with the plossl.

Now in the third picture, I camera zoomed to the max of 3x. Notice how the magnification is now close to double (47x) that of the Pentax at 24mm (26x) but the true field of view or the area is the same (look at the edges along the wooden rail). Thus the 40mm plossl allows you to see more and find objects more easily.

While I was downloading the pictures from my camera to computer, the thought occurred to me that the 40mm plossl may be able too allow the user to digiscope birds in flight. Its wide true field allows the digiscoper to find and track the birds more easily. Its largest exit pupil (about 6.25mm on the 100ED and 6.67mm on the 65ED) would facilitate very high shutter speeds. Finally, the great depth of field would allow the picture of the bird in flight to be more easily taken in 3D space.

The pictures should be take with no camera zoom in order not to reduce the true field of view. Just make sure the camera is set to the highest resolution so that there will still be alot of pixels to cut out of the unvignetted area.

Can Popper said:

After my wife saw your picture, I finally got approval to buy one...thanks!

When you say you still get vignetting, are you referring to the dark areas around the circle of the image, like the no camera zoom pictures I took with my narrower field eyepieces? If yes, that you need to try a long eyerelief, super widefield eyepiece next.

Click to expand...

Can
Sorry, I think that I missed this post! Yes, vignetting = dark circular area around the image. What lens would you suggest that I try next? This lens malarky is starting to get expensive! I've not got an Astro 8 - 24 zoom which is no use for digiscoping, the orginal cheapo 15mm also not enouth eye relief, a 12.5 mm ED, and now the 32 mm Celstron Plossl bought on your advice, which si the one used for the Bullfinch photo. If I'm going to shell out again, I need (ideally) more depth of field, poss more eye relief and maybe less magnification.....

John

John Fleet said:

Can
Sorry, I think that I missed this post! Yes, vignetting = dark circular area around the image. What lens would you suggest that I try next? This lens malarky is starting to get expensive! I've not got an Astro 8 - 24 zoom which is no use for digiscoping, the orginal cheapo 15mm also not enouth eye relief, a 12.5 mm ED, and now the 32 mm Celstron Plossl bought on your advice, which si the one used for the Bullfinch photo. If I'm going to shell out again, I need (ideally) more depth of field, poss more eye relief and maybe less magnification.....

John

Click to expand...

Hi John,
I'm glad you asked because I was looking for the exact same thing. The ideal eyepiece that you and I were looking for must have:
1. Long eyerelief
2. Lowest power
3. Widest Field of View
Unfortunately the above three starts trading each other off at around 20mm.

Thus, the best candidates I've found are the:
1. Pentax XW 20mm - 70 degree FOV
2. Orion Stratus 21mm - 68 degree FOV
3. Vixen Superwide Lanthanum 22mm - 65 degree FOV
4. Siebert Ultra 24mm (reviewed above-it was my choice) - 65 degree FOV
5. Televue Panoptic 24mm* - 68 degree FOV but only 15 mm eyerelief
6. Orion Epic 25mm - 55 degree FOV (only inexpensive eyepiece out of the bunch)
7. Siebert Ultra 28mm - 60 degree FOV

All seven will work well with the Pentax and have good to awesome optics; also they all have eyerelief of at least 20mm (except the Panoptic). With the exception of the Epic, the rest belong to the highest end ($$$).

So out of this list, you are faced with a choice. Do you want a wider field and thus use less camera zoom to eliminate vignetting? If yes, go for eyepieces on the top of the list. Or do you want better depth of field and slightly more use of camera zoom to eliminate vignetting? If yes, then go for the bottom of the list. Maybe you want the combination of both, then the middle of the list would be best.

Choices...Choices...

*EDIT* I'm attaching some fine pictures of birds I took with the Siebert Ultra 24mm. Notice in the 2 birds picture how the wide field could accomodate both birds with good depth of field.

Thank you for your advice on 32 GTO plossl with a pentax 100ED

I just purchase a Pentax 100 ED. As I do not believe in the compromising quality of zoom pieces, I bought the scope with a pentax eyepiece W14 (42X magnification) which is superb! But I enjoy as equally the 32 mm GTO Plossl I purchased fo $30 from Hands-on optics. The latter will likely stay on all the time for general birding and I will shift to the much more expensive Pentax eyepiece when I will need more scrutiny on some distant bird!
Thank you again!