I'm buying this for an 8" Orion SkyQuest. I'm most interested in using it for pictures of the upcoming eclipse and transit. Can anyone weigh the pros and cons of glass vs film for this purpose? the $50 difference in the full aperture vs off-axis doesn't make much difference to me. On Mon, Apr 23, 2012 at 9:17 AM, <erikhansen@thebluezone.net> wrote:
You are right the off-axis filters are quite a bit less expensive. Thousand Oaks 8" full ap is almost $140 off axis $90.
Here are a couple of pros and cons of an off-axis filter, in my view:
Pros The filter would be smaller so should be less expensive Since it is off axis, there would be no diffraction spikes from the spider, but we are talking the sun, so this is pretty much a non issue.
Cons Smaller aperture so less theoretical resolution Dimmer views, but again we are talking the sun, so this is pretty much a non issue
Personally, I would recommend a full aperture filter. If you are good with your hands, or want to come to an ATM session, you can easily make your own filter cell for a film type filter. If you do opt to come to an ATM session, you can take a look at my DIY solar filter cell for my 8" dob.
Mat
-----Original Message----- From: utah-astronomy-bounces@mailman.xmission.com [mailto:utah-astronomy-bounces@mailman.xmission.com] On Behalf Of
Chrismo
Sent: Monday, April 23, 2012 1:25 AM To: Utah Astronomy Subject: Re: [Utah-astronomy] solar filters
I'm thinking about getting a glass filter for my 8" dob. Should I use an off-axis for this? I don't understand what difference it makes tho. Can anyone shed some light on this? Thanks!
On Sun, Apr 22, 2012 at 10:09 PM, Joe Bauman <josephmbauman@yahoo.com>wrote:
William, I would go with the outside diameter of the sun-ward side of the tube. Don't cut it close by thinking you only need to cover the glass part. Also, you never use a filter over the eyepiece because the concentrated light would break it. The correct filter must keep almost all of the sunlight from entering the tube in the first place. -- Joe
________________________________ From: william baker <baker464b@yahoo.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Sunday, April 22, 2012 10:04 PM Subject: Re: [Utah-astronomy] solar filters
When figuring out which filter to go with, what to you measure on you telescope, the inside diameter, or the outside diameter of the lip of the scope? Just want to make sure I order the correct one the first time.
Bill
________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Saturday, April 21, 2012 12:43 PM Subject: Re: [Utah-astronomy] solar filters
It is where I got my Baeder Solar Filter for my Lumicon 80mm. Nice filter good workmanship.
I have and know others who have. I found them to be reputable and safe.Steve
Date: Sat, 21 Apr 2012 09:32:05 -0700 From: baker464b@yahoo.com To: utah-astronomy@mailman.xmission.com Subject: Re: [Utah-astronomy] solar filters
Have you purchased anything from this company?
________________________________ From: "erikhansen@thebluezone.net" <erikhansen@thebluezone.net> To: Utah-Astronomy@mailman.xmission.com Sent: Saturday, April 21, 2012 9:39 AM Subject: [Utah-astronomy] solar filters
For those wishing to buy solar filter for eclipse, this company has all sizes in-stock and ready to ship.
http://www.astrozap.com/scripts/prodList.asp?idCategory=31
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