Re: dob tube length vis a vis CMOS imagers
Mike, ? I should have said, the focal length of the primary mirror stays the same.? Adding a focal reducer changes the effective f/ratio of the system.? My 17.5” ServoCAT equipped TeleKIT is f/4.8.? With the use of a focal reducer, the system acts at f/3. ? Yours truly, ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ?
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From: [email protected] <[email protected]> On Behalf Of Jack Huerkamp via groups.io
Sent: Monday, May 13, 2024 9:45 AM
To: [email protected]
Subject: Re: [ServoCAT] dob tube length vis a vis CMOS imagers? Mike, ? When a focal reducer is used with a camera or an eyepiece, the effect is moving the focal plane inward toward the secondary.? All shortening the truss poles does is push the focal plane further out the focuser.? The focal length of the system stays the same.? This can result in part of the light cone from the primary not being captured by the secondary.? As some have mentioned, a larger secondary may be needed to more fully illuminate the FOV when the truss poles are shortened. ? Yours truly, ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ? ? Can you shorten the tube length?? The purpose of the truss system is to hold the secondary mirror at the correct focal length away from the primary mirror.? Seems to me if the focal length is 1524mm (60 inches), that it has to stay at that length.? Am i missing something?
? On Mon, May 13, 2024 at 9:03?AM K9RX - Gary via <amateurK9RX=[email protected]> wrote: Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: dob tube length vis a vis CMOS imagers
Mike, ? When a focal reducer is used with a camera or an eyepiece, the effect is moving the focal plane inward toward the secondary.? All shortening the truss poles does is push the focal plane further out the focuser.? The focal length of the system stays the same.? This can result in part of the light cone from the primary not being captured by the secondary.? As some have mentioned, a larger secondary may be needed to more fully illuminate the FOV when the truss poles are shortened. ? Yours truly, ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ?
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From: [email protected] <[email protected]> On Behalf Of Michael Dreis via groups.io
Sent: Monday, May 13, 2024 9:06 AM
To: [email protected]
Subject: Re: [ServoCAT] dob tube length vis a vis CMOS imagers? Can you shorten the tube length?? The purpose of the truss system is to hold the secondary mirror at the correct focal length away from the primary mirror.? Seems to me if the focal length is 1524mm (60 inches), that it has to stay at that length.? Am i missing something?
? On Mon, May 13, 2024 at 9:03?AM K9RX - Gary via <amateurK9RX=[email protected]> wrote: Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: dob tube length vis a vis CMOS imagers
Gary, Night before last Blackeye galaxy with 100 seconds (10 stacks of 10 second exposure) from my UC18 and DS10cTEC.? Just a little post processing to add the text and remove my background gradient. 
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Re: dob tube length vis a vis CMOS imagers
Gary, My black and white "EAA" images with "almost" no post processing. 
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Re: dob tube length vis a vis CMOS imagers
Mike,
The backfocus of the camera requires you to have some extra focus travel to bring the camera sensor to the focal plane.? My UC18 telescope has plenty of focus travel and have range to spare when I place cameras into my focuser with 17.5mm of backfocus.
Richard
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Re: dob tube length vis a vis CMOS imagers
Gary,
When Dave K. recommended Mallincam cameras for his Obsession customers I took the bait.
The Mallincam DS series of cameras only have a backfocus of 17.5mm.? This means no modification was required to my UC18 trusses.?
I own the DS287m, the DS287c and the DS10cTEC cameras.
When I install a Mallincam DS series camera into my Feather Touch focuser I still have 3/4" of focus travel remaining.
For EAA I recommend a very sensitive camera for instant gratification.? I recommend the most sensitive camera from Mallincam--the DS287 series of cameras.? The black and white camera DS287m is the most sensitive.??
The first time you point your telescope and camera at M42 or M51 your jaw will drop at the instant image you will see.
I imaged M42 before I purchased my ServoCAT and just pointed my telescope in front of the nebula and configured my DS287m to take a photo every 6 seconds as the nebula drifted across my field of view.? My exposure was set to 100 mS.? Then I stitched the images together for a wonderful larger image.
For big time EAA parties, I mirror my laptop onto my big screen TV in my living room.
Richard
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Re: dob tube length vis a vis CMOS imagers
Gary,
Can you shorten the tube length?? The purpose of the truss system is to hold the secondary mirror at the correct focal length away from the primary mirror.? Seems to me if the focal length is 1524mm (60 inches), that it has to stay at that length.? Am i missing something?
On Mon, May 13, 2024 at 9:03?AM K9RX - Gary via <amateurK9RX= [email protected]> wrote: Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: dob tube length vis a vis CMOS imagers
Hi Gary, again lol. Now that I read you have an F5 mirror you may not need to shorten your truss tube unless as Jack said you use a focal reducer. My scope is an F3.3 so It was built with an adjustment built in.
Mickey
On Monday, May 13, 2024 at 09:03:22 AM EDT, K9RX - Gary <amateurk9rx@...> wrote:
Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
|
Re: dob tube length vis a vis CMOS imagers
On Monday, May 13, 2024 at 09:44:47 AM EDT, Jack Huerkamp <mallincamusa@...> wrote:
Gary, I currently use the DS10cTec but I am considering the DS26 28.3 diagonal IMX571 sensor. Hi Jack. ? When I first started using MallinCam cameras on my 17.5” TeleKit, I had to shorten the truss poles 1” to allow the scope to focus when using a focal reducer on the camera.? Without the focal reducer, I would have achieved focus but with the small CCD camera sensors in the cameras at that time, the FOV at f/4.8 would have been extremely small.? With the focal reducer, I was running close to f/3.? Current MallinCam cameras have sensors ranging up to 28.3mm measured diagonally, but the camera I would suggest would be the DS10cTEC.? It is a 10.7MP camera with 4.63 micron pixels, no amp glow and the sensor is 21.8mm measured diagonally.? I have several customers using this camera on their obsession telescopes and have reached out to them to see if they would get with you. ? I would have sent you some images with my scope, but I have not been using it now that I have a permanent observatory with a 16” RC in it.? Lugging out the 17.5” and setting it up to observe in SE Louisiana is not as easy as it was 20 years ago when I got the ServoCAT for it. ? Yours truly, ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ?
From: [email protected] <[email protected]> On Behalf Of K9RX - Gary via groups.io
Sent: Monday, May 13, 2024 8:03 AM
To: [email protected]
Subject: [ServoCAT] dob tube length vis a vis CMOS imagers ? Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: dob tube length vis a vis CMOS imagers
Hi Gary. I own a Meade LightBridge 12" F5 (as you probably recall), mostly for visual, but recently trying to turn it into an EAA platform - that's why I was asking about the ASIAir. I had no backfocus issues with a ZWO ASI1600MC/C and Baader MPCC/filters/etc. so far. I don?t have any deep space image to show you, but here some planetay images I was able to gather in some sessions in the past - focus should be the same both planetary and deep space.
HTH. Sincerely,
Ricardo.
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Re: dob tube length vis a vis CMOS imagers
Gary, ? When I first started using MallinCam cameras on my 17.5” TeleKit, I had to shorten the truss poles 1” to allow the scope to focus when using a focal reducer on the camera.? Without the focal reducer, I would have achieved focus but with the small CCD camera sensors in the cameras at that time, the FOV at f/4.8 would have been extremely small.? With the focal reducer, I was running close to f/3.? Current MallinCam cameras have sensors ranging up to 28.3mm measured diagonally, but the camera I would suggest would be the DS10cTEC.? It is a 10.7MP camera with 4.63 micron pixels, no amp glow and the sensor is 21.8mm measured diagonally.? I have several customers using this camera on their obsession telescopes and have reached out to them to see if they would get with you. ? I would have sent you some images with my scope, but I have not been using it now that I have a permanent observatory with a 16” RC in it.? Lugging out the 17.5” and setting it up to observe in SE Louisiana is not as easy as it was 20 years ago when I got the ServoCAT for it. ? Yours truly, ? Jack ? Jack Huerkamp Jack's Astro Accessories, LLC 38388 Pine Street Pearl River, LA 70452-5192 985-445-5063 mallincamusa@...
30.37N? 89.76W ? All of us get lost in the darkness.
Dreamers learn to steer by the stars. ………………………………….Neil Peart ? ? ?
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From: [email protected] <[email protected]> On Behalf Of K9RX - Gary via groups.io
Sent: Monday, May 13, 2024 8:03 AM
To: [email protected]
Subject: [ServoCAT] dob tube length vis a vis CMOS imagers? Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: dob tube length vis a vis CMOS imagers
Hi Gary, If I remember correctly I did not need to shorten my truss poles initially when I was using my camera only (asi294MCPro) and cona corrector. It was only after I wanted to try using a nexus focal reducer that I needed more back focus. I’m using an 18” f4.3 dob that has a low profile feather touch mounted to the astrosystems filter slider. I had a falcon rotator that I had wanted to add into the image train but it needed so much more back focus when added. It would have made the truss poles extremely tight where they mount to the upper cage due to even more shortening so I sold it. One thing you also should check is to see if a larger secondary mirror will help provide a more fully illuminated image circle. I upgraded my secondary from a 3.5” to a 4” and I did notice images improved a fair amount.
Mike
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On May 13, 2024, at 9:03?AM, K9RX - Gary via groups.io <amateurK9RX@...> wrote:
?Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
|
dob tube length vis a vis CMOS imagers
Hello all... so - there are a few guys on here that have done imaging using their Obsession or similar dob. I'm curious what I should expect to have to do with the truss tube length. I have heard, anecdotally, that the length has to be shortened, that there isn't enough 'range' in a typical system/focuser to accommodate a normal CCD system. Anyone have an idea what to expect??
Also I'm thinking of the ZWO 533 as a starter... I want to stay away from amp glow. Note I'm not looking for outstanding images that require hours of post-processing. Just looking to do EAA work for outreach but want a decent enough camera that I can do some longer term (short exposure, lots of stacking) imaging. Thoughts here as well would be welcome.?
Gary Myers
12" F5 Obsession
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Re: HELP! MY MESSAGE HAS BEEN LOCKED!!
Steve,?
My apologies - I should have announced it. I did it. It was indeed just that discussions of ASIAir are for the moment premature. There's a lot of effort that would have to happen before it's germane. You're more than welcome to start a new thread on the "Smart ServoCAT" topic.?
Gary
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Re: HELP! MY MESSAGE HAS BEEN LOCKED!!
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Re: HELP! MY MESSAGE HAS BEEN LOCKED!!
Steve, in other forums some threads are locked to prevent further comments, once the original question was sufficiently answered [at moderator's judge) and to avoid confusions
It seems this is would be the case, as so far Gary confirmed there's no way ServoCAT can talk to ASIAir, and there's work going on in that regard. If that's the case there'd be nothing wrong with your (or any) comments, just standard procedure
Just my best guess. Sincerely,
Ricardo
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HELP! MY MESSAGE HAS BEEN LOCKED!!
Hi All. I just found out that my message has been locked. Probably something I did???
Anyway, I tried to find out how to unlock it, but to no avail.
Can anyone help?? ?Please!
Steve
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Sounds great. Hope you can finally get outside soon. Steve?
On Fri, May 10, 2024 at 9:28?AM K9RX - Gary via <amateurK9RX= [email protected]> wrote: Its been some time since I had the 12" set up... it's now sitting in our "smallish" living room... as a test for it - while waiting for a clear night. When I get up in the morning I'll find a galaxy rising in the east (AN MODE IDENTIFY) - GOTO it - turn on AutoLOCK ... it just brings a smile on my face when I look at the AN readout sitting at 0.00 0.00 for hours on end. It goes to 0.01 occasionally ... but the average is right at 0.00! On this scope, using 20000 count (S1, smaller body) encoders, that is just a hair over 1 arcmin!
For those that haven't used the latest firmware - and haven't used AutoLOCK... just a heads up. It really works extremely well.?
Gary Myers
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Its been some time since I had the 12" set up... it's now sitting in our "smallish" living room... as a test for it - while waiting for a clear night. When I get up in the morning I'll find a galaxy rising in the east (AN MODE IDENTIFY) - GOTO it - turn on AutoLOCK ... it just brings a smile on my face when I look at the AN readout sitting at 0.00 0.00 for hours on end. It goes to 0.01 occasionally ... but the average is right at 0.00! On this scope, using 20000 count (S1, smaller body) encoders, that is just a hair over 1 arcmin!
For those that haven't used the latest firmware - and haven't used AutoLOCK... just a heads up. It really works extremely well.?
Gary Myers
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Raphael, I'm guessing - looking at the picture - it is about 2.6" in length ... which would be 66mm. Whichever is closest to the number you see for the length.?
g.
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Jack Huerkamp
Mike