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Posts Made By: James DellaPenna

June 25, 2004 08:23 PM Forum: Equipment Talk

orion shorty with pental xl 7mm

Posted By James DellaPenna

Ralph,

I don't know the focal length of a Burgess 127. If it's an f/10 1200mm you are already at 171x using just the 7mm XL. This puts you near the "practical" limit of power for planetary objects. The Shorty is going to double that to 343x which might be O.K. on star clusters or galaxies under exceptional viewing conditions. On the other hand, if the scope is an f/5 or f/6 it may work O.K.

June 27, 2004 08:27 PM Forum: Refractors

Achromat Question

Posted By James DellaPenna

Ed,

I own a Meade AR-6 and have also looked through a TV-101 and TV-102 owned by other people. I think it is fair to say the extra 2" aperture does provide more resolution but it can not provide the degree of clarity seen in any true APO. The principle culprit is the color abberation effect, even when using a minus violet filter. No matter how many ways you cut it a portion of your light is going to be out of focus.

The other issue is lack of consistency in Synta refractor quality. With APO's you pretty much know what you are going to get. With achromats it's a crap shoot.

I enjoy my achromat very much and tend to use it often during club public viewing events to avoid the cool-down problems inherent with my SCT.

Ed, If you already have the FS-102 I personally do not think a 6" achromat is going to impress you much. You will probably notice the disadvantages before you note the extra resolution.

June 30, 2004 07:13 PM Forum: Mounts

Celestron CG-5 Go-To opinions

Posted By James DellaPenna

I too would like to hear feedback on this mount. I have heard of one particular problem described as "runaway slewing" but no details from anyone who actually experienced it. This may only be pertinent to some of the original models, since worked out with updates.

July 1, 2004 08:39 PM Forum: Equipment Talk

Time for all of us to do our part in supporting AstroMart

Posted By James DellaPenna

I would like to second Mike's comments. It is interesting to note that some of the many "atta boys" that Herb gets for the Astromart site come from folks who offer no financial support. If everyone who has not offered support would just do so for 1 month/year or 1 quarter/year it would go a long way towards maintaining this fantastic site.

July 18, 2004 04:59 PM Forum: Eyepieces

Re: 5mm and smaller

Posted By James DellaPenna

Pentax has the same 20mm eye relief as Radians plus an adjustable eyecup that is smooth vs. click-stop. Lens opening is wide and similar to Radians. I am referring to the XL's and their newer XW replacement.

July 19, 2004 07:32 PM Forum: Equipment Talk

Is C92.5 dovetail for CG-5 compatible to Skyview P

Posted By James DellaPenna

Andre,

Yes, the dovetail is compatible. The C9.25 OTA is at the upper weight limit of both the CG-5 and Sky View Pro mounts. The mounts are about equal and great for visual use but limited to short exposure photography.

July 27, 2004 08:30 AM Forum: Equipment Talk

Re: Eyepiece Eye Relief

Posted By James DellaPenna

The Pentax XL's and XW's also have the eyecups that screw out to just the right position for perfect viewing.

July 28, 2004 08:24 PM Forum: Celestron

Televue 2" Everbrite Star Diagnol and C-9.25SGT

Posted By James DellaPenna

Malcom,

Most SCT's will accept any brand of 2" diagonal. This is accomplished by removing the 1.25" visual back and replacing it with a 2" visual back. I use the one made by Astro-Physics because it has a brass compression ring that tightens all the way around the EP instead of just at one or two points. This visual back also includes a 1.25" adaptor for 1.25" EP's. Some 2" visual backs do not include this adaptor or charge extra for it.

August 6, 2004 12:11 AM Forum: Equipment Talk

Skyview Pro and LXD55 - same counterweight?

Posted By James DellaPenna

Robert,

Orion, Meade, and Celestron counterweights are interchangeable.

August 9, 2004 01:33 AM Forum: Beginning Astronomy?

Viewing conditions

Posted By James DellaPenna

Harry,

I'm inclined to say no, but what type scope, size, brand, eyepieces, and powers are you referring to? There are a lot of variables in play. Mediocre optics really needs to be defined before we can help you with your question.

One important point I will make is that "good enough" seeing in this case implies exceptional seeing. This is a rare occurance for most of us.