Zoom Help (1 Viewer)

Purchased a PF-65ED recently with a XW 14 EP. Would still like to have a zoom though with 60X if possible just for ID purposes in certain situations. The Pentax XF zoom is becoming difficult to find. Can anybody suggest an EP that I could use and not have to modify?

Is a modification needed for the WO zoom?
Also how about the Orion zooms? will they work fine? Adorama sells the Orion 7.5 - 22.5mm Premium for $279.

Thanks. I read through a bunch of posts and just got more confused so my apologies that this has already been covered.

Unlike the XF 8.5mm and 12mm eyepieces, the XF zoom is not that good so you are not missing out by not getting it. Frankly, the PF-65ED does not perform so well above ~45x anyway. Your best bet might be the Vixen 8-24mm zoom.

BK646:

I agree with RJM. I have a PF-65. I first tried the WO Zoom (7.5 to 22.5 mm). I was disappointed with the eyerelief above 30x. Also, although the modification to the scope body is limited to removing the factory compression washer and substituting a smaller home-maded compression washer; it's a pain in the lower posterior to change lenses. I purchased on sale ($150) a Vixen Click Stop Zoom 8-24 mm. No modifications required.

In regard to maximum usable magnification, my Pentax does a very good job with a Vixen NLV, 9 mm EP yielding 43.3x. But, I found that it was very difficult to focus with a Tele Vue Radian 8 mm EP as the depth of field is so narrow. Someone used the expression that "safe cracker's fingers" are required with higher magnification. The Pentax XF zoom does not have a good reputation for spotting scope use, although it's considered to be a decent astronomy zoom. The Vixen zoom with the PF-65 will deliver 16.3-49x; optically it's equal to the WO zoom, no better, no worse. You need an alpha 65 to get good quality 60x or go to an 80 mm scope. Either way it's both bigger, bulkier and a lot more bucks. Good luck.

By the way, I just ordered an Orion Shorty-Plus 2x Barlow. I hope to use it for looking at the moon and perhaps a planet or two. This Barlow is strongly recommended in The Backyard Astronomer. For some reason it no longer appears to be widely available?

berarclawthedonut

Hey BearClaw,

Could you post the results of using the Barlow lens? Interesting little piece that is relatively cheap. Might have to purchase one.

BK646:

Received it yesterday it's been raining (forever) here in Portland. However, I have been able to determine that the 1.25" section that slips into the Pentax PF-65 body is about 3/32" too long to fit all the way inside the body. This caused me to suspect that I would not be able to focus to infinity. Unfortunately, this was easily verified with both my Vixen 8-24mm Zoom and my Vixen NLV 9mm. Both focus to a maximum of about 80 yards. Not much good for looking at the Moon, much less planets. Some EP's will work in the little Pentax scope and some will not. I guess it's the same with Barlows.

With the zoom at all magnifications the barlow produced a very sharp image, although it did get rather dim between 16 and 12 mm. With the barlow in place the zoom was 32.5-97.5x, just could not focus beyond 80 +/- yards. It was also very sharp in the 9 mm (87x).

I'll give Adorama a call tomorrow and touch base with them to see if they know of any magic that might allow it to work. Regrettably, it will probably have to go back.

bearclawthedonut

bearclawthedonut said:

BK646:

Received it yesterday it's been raining (forever) here in Portland. However, I have been able to determine that the 1.25" section that slips into the Pentax PF-65 body is about 3/32" too long to fit all the way inside the body. This caused me to suspect that I would not be able to focus to infinity. Unfortunately, this was easily verified with both my Vixen 8-24mm Zoom and my Vixen NLV 9mm. Both focus to a maximum of about 80 yards. Not much good for looking at the Moon, much less planets. Some EP's will work in the little Pentax scope and some will not. I guess it's the same with Barlows.

With the zoom at all magnifications the barlow produced a very sharp image, although it did get rather dim between 16 and 12 mm. With the barlow in place the zoom was 32.5-97.5x, just could not focus beyond 80 +/- yards. It was also very sharp in the 9 mm (87x).

I'll give Adorama a call tomorrow and touch base with them to see if they know of any magic that might allow it to work. Regrettably, it will probably have to go back.

bearclawthedonut

Click to expand...

If it is at all possible, screw the barlow element off the tube and screw directly into eyepiece. This may just work for you. I have successfully used this method to get 'difficult' eyepieces to focus at infinity.

Rmel66.

The three Barlow elements are mounted/located in the 1.25" tube. The slightly larger diameter "body" above the 1.25" tube is just a cylinder to receive the EP 1.25" tube. The total length of this Barlow is 2.75", pretty compact. So, I see no way for this barlow to work in my PF-65. Too bad as the image quality was very high. As I previously mentioned The Backyard Astronomer strongly recommended this 3 element Barlow. This Barlow is made to be used with telescopes. My little Pentax is hardly a telescope.

bearclawthedonut