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Newbie advice please

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  • tonyrieko
    Hi I’m Tony in Australia. I just bought a Mallincam DS2.3Plus for video ‘live’ viewing; it’s very impressive. I now want to get a guide camera and
    Message 1 of 8 , May 6, 2017


      Hi I’m Tony in Australia. I just bought a Mallincam DS2.3Plus for video ‘live’ viewing; it’s very impressive. I now want to get a guide camera and I’d like some advice please. I have a William Optics FLT98 refractor on an EQ6-R goto mount; it has a 50mm f/4 guidescope.

      What would be a good basic guide camera for not a large investment?

      But I’m also wondering if I should just get a CCD which could also do imaging [and I can use the Mallincam as a guide camera]. This means a larger investment; I know but my budget is quite low - $500-$1000.

      I’m going crazy trying to differentiate all the stuff on offer.

      Do you recommend CCD over CMOS and cooled over uncooled. I assume the answer is yes to these two. So is there anything available in my budget range or is that just unrealistic?

      Any advice will be appreciated – but I am a total newbie in the world of CCDs so please simplify any technical parts.

      Thanks a lot

      Tony


    • Steven Claver Leiden
      Tony, Your Mallincam DS2.3Plus is a guide camera as well as a video camera for both visual and astrophotography. I’m pretty sure it even has an interface
      Message 2 of 8 , May 7, 2017

        Tony,

         

        Your Mallincam DS2.3Plus is a guide camera as well as a video camera for both visual and astrophotography. I’m pretty sure it even has an interface with PHD2.

        I have the same camera, but actually have not tried the guiding capability. It would seem appropriate to at least find out how good the Mallincam can work for you.

         

        Steve

         

        From: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com]
        Sent: Sunday, May 7, 2017 1:55 AM
        To: ccd-newastro@yahoogroups.com
        Subject: [ccd-newastro] Newbie advice please

         

         

         

        Hi I’m Tony in Australia. I just bought a Mallincam DS2.3Plus for video ‘live’ viewing; it’s very impressive. I now want to get a guide camera and I’d like some advice please. I have a William Optics FLT98 refractor on an EQ6-R goto mount; it has a 50mm f/4 guidescope.

        What would be a good basic guide camera for not a large investment?

        But I’m also wondering if I should just get a CCD which could also do imaging [and I can use the Mallincam as a guide camera]. This means a larger investment; I know but my budget is quite low - $500-$1000.

        I’m going crazy trying to differentiate all the stuff on offer.

        Do you recommend CCD over CMOS and cooled over uncooled. I assume the answer is yes to these two. So is there anything available in my budget range or is that just unrealistic?

        Any advice will be appreciated – but I am a total newbie in the world of CCDs so please simplify any technical parts.

        Thanks a lot

        Tony

         

      • Steve C. Mitchell, Sr., O.D.
        Hey Tony, If you use your Mallincam video camera, you don’t need a guide camera. The video rate is plenty fast enough not to need any guiding. You should be
        Message 3 of 8 , May 7, 2017

          Hey Tony,

          If you use your Mallincam video camera, you don’t need a guide camera. The video rate is plenty fast enough not to need any guiding. You should be able to get some nice planetary and lunar images with it and probably a few bright deep space objects. If you want to take deep space images you’ll need to get a CCD, then you’d need a guide setup because you want to take images of several minutes to get the best results. You could then use the Mallincam as the guide camera. As far as a cooled CCD camera, I haven’t looked lately, but there are probably several options available at many online distributors.

          If I were you, I’d play with what you have first and get the hang of it with the video camera and learn to get the most out of it before moving on up the ladder. The learning curve is long and steep, but I think it’s a fun trip in itself.

          Steve

           

          From: ccd-newastro@yahoogroups.com [mailto:ccd-newastro@yahoogroups.com]
          Sent: Sunday, May 07, 2017 12:55 AM
          To: ccd-newastro@yahoogroups.com
          Subject: [ccd-newastro] Newbie advice please

           

           

           

          Hi I’m Tony in Australia. I just bought a Mallincam DS2.3Plus for video ‘live’ viewing; it’s very impressive. I now want to get a guide camera and I’d like some advice please. I have a William Optics FLT98 refractor on an EQ6-R goto mount; it has a 50mm f/4 guidescope.

          What would be a good basic guide camera for not a large investment?

          But I’m also wondering if I should just get a CCD which could also do imaging [and I can use the Mallincam as a guide camera]. This means a larger investment; I know but my budget is quite low - $500-$1000.

          I’m going crazy trying to differentiate all the stuff on offer.

          Do you recommend CCD over CMOS and cooled over uncooled. I assume the answer is yes to these two. So is there anything available in my budget range or is that just unrealistic?

          Any advice will be appreciated – but I am a total newbie in the world of CCDs so please simplify any technical parts.

          Thanks a lot

          Tony

           

        • phils67
          Do you own a DSLR? if you do, then you could use it for imaging and use your Mallincam as a guide camera. It s my belief that current DSLRs are good enough
          Message 4 of 8 , May 8, 2017
            Do you own a DSLR? if you do, then you could use it for imaging and use your Mallincam as a guide camera. It's my belief that current DSLRs are good enough that you need to get into the world of cooled monochrome astro cameras ($$$) with filters ($$$$)  to get significant improvements over what the DSLR is capable of doing. There's no argument that a specialized camera will give better results but the question you need to ask is "are the potential better results justified by the investment I'll need to make in time and money."

            A few caveats though:
            1. DSO imaging with longer exposures requires a much more capable mount that visual or planetary imaging.
            2. You'll need to guide for longer exposures which usually means a separate guide scope or an off-axis guider.
            3. Polar alignment is critical for longer exposures. You should be less than 30 arcsec off in your polar alignment, This is achieved using PHD2, plate solving, a Polemaster, or visual / photographic drift alignment.

            Your mount is more than adequate for long exposure imaging with your scope. If you can attach the Mallincam to the finder then you'll have a guide scope. You'll need a planetarium program (ie CdC), the ASCOM platform, and EQMOD to handle pointing your scope. PHD2 for guiding, with pulse guide to eliminate the extra ST4 guide cable works very well with these mounts. You can use the hand controler set to "PC Direct" mode or Shoestring Astronomy's EQDIR box to convert a standard serial signal to the TTL signals required by the mount. An alternative to these is to get a USB to serial adapter that outputs TTL signal levels (0,+5V) instead of the standard serial (+12, -12 or +5, -5) voltages. If you use a USB to serial adapter, ones made with the FTDI chipset work best with EQMOD.

            You'll need an astro imaging program to control the camera. For DSLRs, there's BYEOS or BYN for Canon or Nikon cameras respectively. Images Plus Camera Control is another option for these that also supports any astro camera with an ASCOM interface. SGP and Maxim DL are two other commercial programs (there are more) and there's a number of downloadable packages that will run both DSLRs and astro cameras.

            Welcome to the wonderful world of imaging.

            Phil
          • waddington50
            Hi Phil. FWIW, I don t agree with your comment about polar alignment, I think a goal of 30 arc-sec is excessive, especially for a beginner. Polar
            Message 5 of 8 , May 8, 2017
              Hi Phil.  FWIW, I don't agree with your comment about polar alignment, I think a goal of 30 arc-sec is excessive, especially for a beginner.  Polar misalignment generally has two effects: 1) a steady drift in declination, and 2) field rotation as you move closer to the pole.  The steady drift is handled well by any competent guiding software and certainly by PHD2.  The importance of the field rotation depends on the size of your photographic field of view, the image scale, and how close to the pole you're imaging.  There are a number of good online calculators that will tell you how much rotation you'll get at any particular setup and pointing position.  In many cases, some amount of polar misalignment actually improves guiding with mounts that have significant Dec backlash, which many do.  Speaking from personal experience, I've had a permanent set-up for many years and have never bothered to tune the polar alignment below a few arc-minutes - and I've never seen any field rotation while imaging at 0.6 arc-sec/px.  I'm only mentioning this because there seem to be a lot of people who spend far too much time doing polar alignment and far too little time imaging. <g>  In any case, the numbers don't lie, the field rotation calculators will tell the story.

              Just my 2-cents worth.
              Bruce
            • Ron Wodaski
              There’s another factor that plays a role. The further you are off the pole, the greater the noise contribution in guiding. This gets worse with longer focal
              Message 6 of 8 , May 8, 2017
                There’s another factor that plays a role. The further you are off the pole, the greater the noise contribution in guiding. This gets worse with longer focal lengths, and better with a high quality mount (though there can be some small contributions specific to high-qlaity mounts that become noticeable at long focal lengths due to idiosyncrasies in the design). 

                Based on my personal experience with a wide range of mount quality and focal length, I have found that most of the time, a more accurate polar alignment helps improve guiding because of this noise problem. Basically, the smaller the adjustment, the less likely you are to bounce around. if the noise in the mount itself swamps this, then it’s just a matter of luck whether the noise from a larger polar guiding error matters or not. 

                I’ve never run into a situation where a large polar offset effectively loaded the mount to prevent backlash problems. Generally, I consider backlash a critical fix issue. :) But I understand the concept, and at shorter focal lengths it’s possible that it’s effective. I just would always rather minimize the backlash, even if that means buying a new mount (a strategy I employed early on, but not everyone will do without food in order to get a better mount…it can be taxing). <joke!>

                I think getting polar alignment < 2’ works for a lot of situations. Modeling software and the noise inherent in guiding and seeing may make it hard to get below that level in a meaningful way. But if you, then do so. The statistics are always in your favor if you do. :) 

                As for field rotation, that’s a much more deterministic item. You can either adjust your exposure time as needed, or you can optimize for minimal field rotation to get longer exposures if they are justified (they only matter in really dark skies).  I’ve had sites where 45 minutes was a reasonable exposure time; I’ve imaged at sites where anything over 1 minute was not justified by the sky brightness. <shrug> Bottom line should be simple: if you have rotation, fix it either with shorter exposures or a better polar alignment. 

                But if you have guiding problems, polar alignment is just one variable. OPTIMIZE THAT VARIABLE FOR YOUR SETUP, and also spend some time on other variables (differential flex for external guiders, mirror shift, seeing conditions, sky darkness (yeah, some of these involve “image somewhere else,” it’s always on our minds…)

                Ron Wodaski
                rwodaski@...



                On May 8, 2017, at 9:00 PM, bw_msg01@... [ccd-newastro] <ccd-newastro@yahoogroups.com> wrote:

                Hi Phil.  FWIW, I don't agree with your comment about polar alignment, I think a goal of 30 arc-sec is excessive, especially for a beginner.  Polar misalignment generally has two effects: 1) a steady drift in declination, and 2) field rotation as you move closer to the pole.  The steady drift is handled well by any competent guiding software and certainly by PHD2.  The importance of the field rotation depends on the size of your photographic field of view, the image scale, and how close to the pole you're imaging.  There are a number of good online calculators that will tell you how much rotation you'll get at any particular setup and pointing position.  In many cases, some amount of polar misalignment actually improves guiding with mounts that have significant Dec backlash, which many do.  Speaking from personal experience, I've had a permanent set-up for many years and have never bothered to tune the polar alignment below a few arc-minutes - and I've never seen any field rotation while imaging at 0.6 arc-sec/px.  I'm only mentioning this because there seem to be a lot of people who spend far too much time doing polar alignment and far too little time imaging. <g>  In any case, the numbers don't lie, the field rotation calculators will tell the story.

                Just my 2-cents worth. 
                Bruce


              • Ron Wodaski
                BTW: I had a deep conversation about mounts with Bruce, and I think I can safely say he knows his stuff. I noted that I had not had much experience, for
                Message 7 of 8 , May 9, 2017
                  BTW: I had a deep conversation about mounts with Bruce, and I think I can safely say he knows his stuff. I noted that I had not had much experience, for example, with using a large polar offset to help deal with a mount with backlash issues. Bruce has some good ideas about how to solve those kinds of problems creatively. 

                  So I will walk back my response somewhat, and defer to Bruce’s suggestions about that (and some of the other things he mentioned). I still prefer the idea of too much mount, but that can get expensive fast. The idea of getting most out of what you have is a good on. :)

                  Ron Wodaski
                  rwodaski@...



                  On May 8, 2017, at 9:12 PM, Ron Wodaski rwodaski@... [ccd-newastro] <ccd-newastro@yahoogroups.com> wrote:

                  There’s another factor that plays a role. The further you are off the pole, the greater the noise contribution in guiding. This gets worse with longer focal lengths, and better with a high quality mount (though there can be some small contributions specific to high-qlaity mounts that become noticeable at long focal lengths due to idiosyncrasies in the design). 


                  Based on my personal experience with a wide range of mount quality and focal length, I have found that most of the time, a more accurate polar alignment helps improve guiding because of this noise problem. Basically, the smaller the adjustment, the less likely you are to bounce around. if the noise in the mount itself swamps this, then it’s just a matter of luck whether the noise from a larger polar guiding error matters or not. 

                  I’ve never run into a situation where a large polar offset effectively loaded the mount to prevent backlash problems. Generally, I consider backlash a critical fix issue. :) But I understand the concept, and at shorter focal lengths it’s possible that it’s effective. I just would always rather minimize the backlash, even if that means buying a new mount (a strategy I employed early on, but not everyone will do without food in order to get a better mount…it can be taxing). <joke!>

                  I think getting polar alignment < 2’ works for a lot of situations. Modeling software and the noise inherent in guiding and seeing may make it hard to get below that level in a meaningful way. But if you, then do so. The statistics are always in your favor if you do. :) 

                  As for field rotation, that’s a much more deterministic item. You can either adjust your exposure time as needed, or you can optimize for minimal field rotation to get longer exposures if they are justified (they only matter in really dark skies).  I’ve had sites where 45 minutes was a reasonable exposure time; I’ve imaged at sites where anything over 1 minute was not justified by the sky brightness. <shrug> Bottom line should be simple: if you have rotation, fix it either with shorter exposures or a better polar alignment. 

                  But if you have guiding problems, polar alignment is just one variable. OPTIMIZE THAT VARIABLE FOR YOUR SETUP, and also spend some time on other variables (differential flex for external guiders, mirror shift, seeing conditions, sky darkness (yeah, some of these involve “image somewhere else,” it’s always on our minds…)

                  Ron Wodaski
                  rwodaski@...



                  On May 8, 2017, at 9:00 PM, bw_msg01@... [ccd-newastro] <ccd-newastro@yahoogroups.com> wrote:

                  Hi Phil.  FWIW, I don't agree with your comment about polar alignment, I think a goal of 30 arc-sec is excessive, especially for a beginner.  Polar misalignment generally has two effects: 1) a steady drift in declination, and 2) field rotation as you move closer to the pole.  The steady drift is handled well by any competent guiding software and certainly by PHD2.  The importance of the field rotation depends on the size of your photographic field of view, the image scale, and how close to the pole you're imaging.  There are a number of good online calculators that will tell you how much rotation you'll get at any particular setup and pointing position.  In many cases, some amount of polar misalignment actually improves guiding with mounts that have significant Dec backlash, which many do.  Speaking from personal experience, I've had a permanent set-up for many years and have never bothered to tune the polar alignment below a few arc-minutes - and I've never seen any field rotation while imaging at 0.6 arc-sec/px.  I'm only mentioning this because there seem to be a lot of people who spend far too much time doing polar alignment and far too little time imaging. <g>  In any case, the numbers don't lie, the field rotation calculators will tell the story.

                  Just my 2-cents worth. 
                  Bruce




                • stan_ccd
                  ... polar alignment, I think a goal of 30 arc-sec is excessive ... A good argument can be made for deliberately offsetting from the pole so as to have a
                  Message 8 of 8 , May 9, 2017
                    "... polar alignment, I think a goal of 30 arc-sec is excessive ..."

                    A good argument can be made for deliberately offsetting from the pole so as to have a consistent direction of DEC drift.  That consistency essentially eliminates the effect of DEC gear lash (slop) because the worm is always turning in the same direction. A "too good" polar alignment results in DEC corrections going both ways, causing the gear lash to manifest frequently resulting in delayed response and over-shooting, both of which degrade tracking.

                    Of course, it's a different story if you have a top notch mount with very little gear lash (or none in the case of direct drive mounts).  Or very well tuned ant-lash circuitry.

                    Stan
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