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12-31-2014, 04:30 PM   #16
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QuoteOriginally posted by Obin Robinson Quote
Dollar for dollar you're going to be able to gather more light more accurately with a good telescope. You can purchase some telescope focusers which have software designed to change focus with temperature and camera lenses do not. On top of that you can find extremely fast or long focal ratio telescopes which would be prohibitively expensive as camera lenses. You can also cool down a telescope and control tube currents in order to limit distortions caused by heat waves and air currents.


The plus side of a camera lens for wide field astrophotography is that the setup time is quicker than with a telescope. The downside is that the camera lens is not as versatile for stellar photography as a real astrograph.


By the way I should mention I own eight telescopes and built my own 4.5" astrograph just for taking pictures of satellites.

obin
Any pictures you can share of your astrograph?

12-31-2014, 05:00 PM   #17
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QuoteOriginally posted by soycory Quote
Any pictures you can share of your astrograph?
Sure!


Here's an old photo and info taken from another forum because right now most of my gear is in storage. We will be moving in a few months.





Here's the rundown of what you see in this photo:
From the ground up here is the entire system.
First the mount:
1) threaded leveling feet (amazon.com)
2) 1/4x20 threaded rods (Lowes)
3) Meade Starfinder EQ pier (local seller)
4) pier to EQ head adapter which I custom made for this pier (metal was from Metal Remnants, Inc)
5) bubble level (Home Depot)
6) Meade LXD-55 equatorial head which I disassembled, polished, tuned, and reassembled to higher than factory specifications (online classifieds)
7) solid aluminum Vixen dovetail (scopestuff.com)
8) 7" OTA rings (agenaastro.com)

The astrograph from back to front:
1) 7" aluminum irrigation pipe rolled on both ends (Hastings Aluminum)
2) Gelid Silent 9 computer fan (Gelidsolutions.com)
3) foam mat and Velcro (Hobby Lobby)
4) urethane mirror cell (Meridian Telescopes)
5) 4.5" primary mirror (Vixen)
6) tube flocking mat (scopestuff.com)
7) 1" secondary mirror from an Edmund Scientific telescope (online classifieds)
8) GSO dual speed crayford focuser (agenaastro.com)
9) foam OTA front cover and Velcro (Hobby Lobby)



Here's a quickie of Saturn taken with this astrograph. I used my Imaging Source CCD to take this photo:



obin
12-31-2014, 08:43 PM   #18
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Join Date: Feb 2009
Location: Kentucky
Posts: 91
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QuoteOriginally posted by Obin Robinson Quote
Sure!


Here's an old photo and info taken from another forum because right now most of my gear is in storage. We will be moving in a few months.





Here's the rundown of what you see in this photo:
From the ground up here is the entire system.
First the mount:
1) threaded leveling feet (amazon.com)
2) 1/4x20 threaded rods (Lowes)
3) Meade Starfinder EQ pier (local seller)
4) pier to EQ head adapter which I custom made for this pier (metal was from Metal Remnants, Inc)
5) bubble level (Home Depot)
6) Meade LXD-55 equatorial head which I disassembled, polished, tuned, and reassembled to higher than factory specifications (online classifieds)
7) solid aluminum Vixen dovetail (scopestuff.com)
8) 7" OTA rings (agenaastro.com)

The astrograph from back to front:
1) 7" aluminum irrigation pipe rolled on both ends (Hastings Aluminum)
2) Gelid Silent 9 computer fan (Gelidsolutions.com)
3) foam mat and Velcro (Hobby Lobby)
4) urethane mirror cell (Meridian Telescopes)
5) 4.5" primary mirror (Vixen)
6) tube flocking mat (scopestuff.com)
7) 1" secondary mirror from an Edmund Scientific telescope (online classifieds)
8) GSO dual speed crayford focuser (agenaastro.com)
9) foam OTA front cover and Velcro (Hobby Lobby)



Here's a quickie of Saturn taken with this astrograph. I used my Imaging Source CCD to take this photo:



obin
So... I would have called that a telescope 😦. I guess I don't understand. The picture of saturn is awesome.
01-01-2015, 01:02 AM   #19
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QuoteOriginally posted by soycory Quote
So... I would have called that a telescope ��. I guess I don't understand. The picture of saturn is awesome.


Thanks! An astrograph is basically a telescope designed for astrophotography. It has to do with certain design parameters geared towards imaging and not towards visual usage. My 4.5" astrograph had a large secondary mirror and the mirrors were placed with imaging in mind. My astrograph was designed to illuminate an APS-C sized sensor without vignetting. The instrument is an f/7.9 and was designed for imaging bright objects such as planets as well as artificial satellites.


obin

01-01-2015, 01:06 AM   #20
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Location: South Bend (Notre Dame), Indiana
Posts: 1,942
QuoteOriginally posted by soycory Quote
Is this the same "T" mount as for Tamron lenses?

It's a 42mm screw mount that isn't the same thing as m42 - different thread pitch. You can read details here: T-mount - Wikipedia, the free encyclopedia
01-01-2015, 04:42 AM   #21
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Posts: 179
QuoteOriginally posted by marcusBMG Quote
mmmm .. what scope are you using?
Apologies, New Year happened!

My scope is a Skywatcher Equinox ED80 (3" aperture, focal length 500mm for f ratio 6.25)
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