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Posts Made By: Robert Howe

December 9, 2008 09:32 AM Forum: TeleVue

field on TV76

Posted By Robert Howe

Hi all

I am trying out a used TV 76. My TV 85 and 102 and Genesis all had perfect point stars across the entire field, so this is the performance that I expect of the 76.

Last night, the 76 showed comets everywhere peripherally, which came to focus--but then the center was out of focus. There was an area (lower left as one sights through the scope) in which no star would focus, they were either wide or double as I focussed in and out.

I used AP and Televue diagonals; EPs included TV 35, 24 and 19 Panoptics; 22, 13 and 9 Naglers; 13 and 8 Ethos. Only the 9 mm Nagler, with the smallest FOV, showed no aberrations; the 8 mm Ethos showed less than any of the others. But the entire FOV of the 9 Nagler would be the central image of the 22 Nagler.

Looking at the moon with a 19 Panoptic, one limb would be clear and the opposite, out of focus.

A star test showed the enlarged image to be considerably out of round. The telescope was well equilibrated when I observed and my TV85 worked perfectly as did a Tak 60.

Any thoughts?

Robert Howe

December 28, 2008 11:23 AM Forum: CCD Imaging and Processing/Solar System

Eclipse Advice sought

Posted By Robert Howe

Hi all

Can anyone advise on the best way to photograph/film a total eclipse of the sun? I plan to bring a small telescope and mount, a digital camera, a video camera. If need be I could add a laptop and a webcam. The photo from 2006 (attached) was taken with a Canon Powershot A95 at 1/1000 second through a Stellarvue 50 mm finderscope. This time I would like to have more sophisticated capabilities. My ideal would be to have dozens of images that could be combined to bring out different levels of exposure, all taken automatically so that I can enjoy the show.

Robert

December 29, 2008 01:30 PM Forum: Digital SLR AstroPhotography

Seeking advice on an eclipse

Posted By Robert Howe

Hi all

Can anyone advise on the best way to photograph/film a total eclipse of the sun? Eclipses are just about the only astronomical thing that I photograph. I plan to bring a small telescope and mount, a digital camera, a video camera. If need be I could add a laptop and a webcam. The photo from 2006 (attached) was taken with a Canon Powershot A95 at 1/1000 second through a Stellarvue 50 mm finderscope.

This time I would like to have more sophisticated capabilities. My ideal would be to have dozens of images that could be combined to bring out different levels of exposure, all taken automatically so that I can enjoy the show.

Robert

February 24, 2009 07:41 PM Forum: Comets

Comet Lulin and what else?

Posted By Robert Howe

I'm almost completely a visual observer but I do like to take photos of things that won't be back, eclipses and comets. Tonight while working on Comet Lulin I found this interloper in one of my frames. AP 130 f/8.35 refractor, AP 900 mount, Canon Eos Rebel, 30 second exposure. Is this a satellite that rotated into a reflecting position during my exposure? What does it mean that the stars that I smeared by touching the shutter button are in the same general shape as the object?

Cheers

Robert Howe

May 25, 2009 09:26 PM Forum: TeleVue

focuser?

Posted By Robert Howe

HI all

I am bringing a TV 85 and TV 76 to photograph the upcoming eclipse; the 85 with a 2x Powermate for the disc, the 76 with a TV 0.8x reducer for the entire corona. I intend to focus both scopes' cameras to infinity the night before using a focussing mask and digital camera.

Would I benefit from upgrading to the TV fine touch focusser? To spend another $400 on this project would annoy me, but I don't want to waste a LOT of work, time, trouble and expense by bringing home out of focus images.

The photo was taken with my 76, focussing by eye through my Canon. Other images that night were not so crisp..

Cheers

Robert

June 13, 2009 03:10 PM Forum: Digital SLR AstroPhotography

Reducing a diagonal

Posted By Robert Howe

Hi ladies and gents,

Preparing to photograph an eclipse at sea, I am trying several combinations of telescopes and cameras. I have a lovely fast refractor that I would like to use for wide field imaging, but the camera only comes into focus if used straight thru with an extender; a 2 inch diagonal is too long by a very slight amount.

For the sake of stability I will have the mount as low as I can; focusing straight through will be difficult even with a solar filter, as I will likely be dazzled by a chance glance of sunlight. Is there any way to shorten the light path of a 2 inch star diagonal? Does anyone sell a shorter 2 inch diagonal?

Cheers

Robert Howe

June 13, 2009 03:13 PM Forum: Refractors

A shorter diagonal?

Posted By Robert Howe

Hi ladies and gents,

Preparing to photograph an eclipse at sea, I am trying several combinations of telescopes and cameras. I have a lovely fast refractor that I would like to use for wide field imaging, but the camera only comes into focus if used straight thru with an extender; a 2 inch diagonal is too long by a very slight amount.

For the sake of stability I will have the mount as low as I can; focusing straight through will be difficult even with a solar filter, as I will likely be dazzled by a chance glance of sunlight. Is there any way to shorten the light path of a 2 inch star diagonal? Does anyone sell a shorter 2 inch diagonal?

Cheers

Robert Howe

June 28, 2009 05:10 AM Forum: Digital SLR AstroPhotography

Camera settings for an eclipse

Posted By Robert Howe

Hi all

For next month's total solar eclipse I will be shooting on a ship. When I did so in 2006, half of my 16 images were in focus. Six of these were faster than 1/800 sec, one was 1/800, one was 1/200. Of my eight which were out of focus, six were slower than 1/800, one was 1/800, one was 1/1250. I used and will be using a remote release. 1/800 seems to be a stop point for shooting on a ship.

My set up for 2006 is shown, this year I will have a Rebel XTi on a Televue 85.

I note that fine eclipse photos (for ex. Denis diCicco's) are often shot at a film speed of ISO 200. Since speed is of the essence here, why not shoot at ISO 1600?

Cheers

Robert Howe

August 5, 2009 03:27 PM Forum: Astro-Physics

nearly-new GTs available

Posted By Robert Howe

In the past month I have seen five Gran Turismos (Gran Turismi?) for sale on Amart, each of them apparently very new, from recent production. Having never observed with one of these telescopes, how does their view compare to a 140 or to the classic 130 f/8.35?

Cheers

Robert

August 12, 2009 04:39 PM Forum: Astro-Physics

Mounting plate incompatability

Posted By Robert Howe

Hi all,

My brain is exploding over a simple mounting plate issue. How does one apply a Losmandy plate to a set of rings with 3.2 inch hole spacing? I have a MakNewt with wonderful rotating rings (photo). The rings are drilled at 3.2 inches and apply perfectly to an AP 900RP (a fifteen inch ribbed mounting plate with keyhole slots), which of course goes perfectly on an AP900 mount.

Now I wish to mount this with 2 AP refractors on said AP900 mount, using a Robin Casady triad bar. I can find no way, other than fabricating a pair of new aluminum block adapters, to get the 3.2 inch spacing converted to the standard AP/ Losmandy 3.5 inch spacing.

Suggestions?

Cheers

RH