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Posts Made By: John Biretta

April 25, 2004 04:19 PM Forum: Equipment Talk


Posted By John Biretta

Assuming you want to stay around $1k, a C-9.25 would
be excellent choice, as already suggested.

An 6" Mak-Newt (INTES MN-61) would also be good, but
6" is a little small for deep sky.

I would be a little weary of scopes that are
"coming out" as new products may have
issues / long delays / etc. unless the company has
a really good track record.

July 25, 2004 07:49 AM Forum: Equipment Talk

Re: Eyepiece Eye Relief

Posted By John Biretta

Ortho eyerelief is something like 80% to 100% of the
focal length. So if eyerelief is not for you, try a
4mm ortho....

August 29, 2004 04:32 AM Forum: Equipment Talk

Re: Tele Vue 'Blem' Eyepieces

Posted By John Biretta

I've puchased several NEAF "blems" over the years,
and was not able to detect any flaw except the
punch mark.

I've also seen a number of TV non-blems with obvious
optical flaws -- circular zones, bubbles in glass,
too much scattering in the cement, field stop in
wrong place, etc.

Go figure.

May 20, 2005 02:03 AM Forum: Refractors

Re: vixen 102

Posted By John Biretta

Can you post a picture? Is there any information
printed around the front lens?

June 7, 2005 04:47 PM Forum: CCD Imaging and Processing/Solar System

Jupiter from Sunday night

Posted By John Biretta

I've really enjoyed everyone's images here. I picked-up
a used ToUcam couple weeks ago, and starting to get some
decent images.

When I look at this image enough I think I see faint wisps
and loops everywhere -- lots of fine low-contrast detail
near resolution limit. Contrast intentionally set fairly low.
There are some very weak horizontal lines which I think are
from the ToUcam compression -- still trying to figure out
that one. Need to learn about photoshop.

StarMaster 11" F5.4 ELT
TV 4x PowerMate / extension tubes / wedge prisms / UV-IR cut
ToUcam 740 / K3CCD / Registax
15 FPS 730/1350 frames

- John B.

June 7, 2005 04:54 PM Forum: CCD Imaging and Processing/Solar System

Mars Monday AM

Posted By John Biretta

Second try at Mars. Seeing not so good; sky getting bright.

StarMaster 11" F5.4 ELT
TV 4x PowerMate / extension tubes / wedge prisms / UV-IR cut
ToUcam 740 / K3CCD / Registax
15 FPS 500/1350 frames

June 8, 2005 03:30 PM Forum: CCD Imaging and Processing/Solar System

Re: A recent Jupiter and Mars

Posted By John Biretta

Very nice! What software are you using to process
and stack? - John B.

June 15, 2005 02:31 AM Forum: CCD Imaging and Processing/Solar System

ToUcam question

Posted By John Biretta

If I look at a single frame from an AVI done with
a ToUcam in 640x480 mode, I see this intermitent pattern
of horizonal stripes. I've seen it from several
ToUcams. The pattern is made of alternate rows
being either high or low, with a peak-to-peak
amplitude of about 10%. The pattern is not stable
at one spot on the detector, but just appears
ramdomly throughout the image.

I'm attaching a blow-up of a small section of a
frame illustrating the pattern. This is from a
flat field. This image has been interpolated 400%
larger just so you can see the pattern, so this looks a
little smoother than the raw original image.

Anyone seen this before or have clues on what causes it?
Or how to get rid of it electronically?

June 15, 2005 04:11 AM Forum: CCD Imaging and Processing/Solar System

Re: A not so boring side...

Posted By John Biretta

Very, very nice!

July 27, 2005 10:04 PM Forum: Refractors

Re: Lens servicing

Posted By John Biretta

There is a very active Unitron discussion group at

There should also be three thin aluminum foil
tabs or spacers between the lens elements
at 120 degrees around the periphery of the lens.
Usually they are sticky paper on one side and
aluminum foil on the other side.
If someone has fooled with the lens, they
might be missing. They are fairly important.

Sometimes there will be an alignment mark at the
edge of the lens elements. Sometimes a pencil
line across both, or an arrow.