Loading ...
Sorry, an error occurred while loading the content.

Re: Advice on TMB 100 F8

Expand Messages
  • Mark Rieck
    If you seek the same optical quality without giving up aperture or speed, the 105/650 is super sweet too. I d try your existing TV reducer flattener first
    Message 1 of 7 , Jan 29, 2009
    • 0 Attachment
      If you seek the same optical quality without giving up aperture or
      speed, the 105/650 is super sweet too. I'd try your existing TV
      reducer flattener first however, to see what you think of those
      results.

      Mark

      --- In tmboptical@yahoogroups.com, "madpc" <madpc@...> wrote:
      >
      > Hi All,
      >
      > Until recently I had been using an Excellent William Optics FLT-98
      When a
      > TMB 100 F8 come up on offer for a swap so I did this.
      > This is the Model reviewed by David Novoselsky on Cloudy nights: -
      > http://www.cloudynights.com/item.php?item_id=462
      >
      > This was reputed to be one of the best 4" APO's ever made.
      >
      > I have recently taken the following pictures with it: -
      > http://www.madpc.co.uk/TMB-100/Copernicus-06-01-09.jpg
      >
      > http://www.madpc.co.uk/TMB-100/M42-19-12-2008b.jpg
      >
      > http://www.madpc.co.uk/TMB-100/Moon-06-01-2009.jpg
      >
      > The Scope delivers a dark background with great contrast so much of
      what the
      > review says is true.
      > This one has the violet coating.
      > Another good point is I don't need a reducer / flattener for my 40D
      as the
      > stars are sharp to the edge.
      > The bit I do miss about the FLT-98 is its faster at F6.3 (Near F5.5
      with the
      > TV reducer flattener) So this seems to allows more light gathering
      powers
      > for 5-6 min exposure.
      > To get the same amount of data of the 40'd sensor with the TMB
      means 8 to 10
      > min exposures.
      > This is all well and good if my skies would allow such long
      exposures
      > regularly.
      > In reality they don't.
      > In some ways I regret letting the FLT 98 go but in other I do not.
      > I suppose the question is do I let the TMB go and get another FLT
      98 or do I
      > persevere with the TMB...
      > I'm sure it has loads to offer.
      > Oh I'm getting a modified Canon 1000D so this might help??
      >
      > Regards,
      >
      > --
      > Paul Gordon
      > paul.gordon4@...
      > http://www.madpc.co.uk
      >
    • dthorman1@aol.com
      Hi Paul, My Dad has a TMB 100/800 Classic I am quite impressed with though he doesn t use it for imaging. I don t have any experience with an FLT 98 but even
      Message 2 of 7 , Jan 29, 2009
      • 0 Attachment
        Hi Paul,
        My Dad has a TMB 100/800 Classic I am quite impressed with though he
        doesn't use it for imaging. I don't have any experience with an FLT 98 but even
        then I am inclined to advise on keeping the TMB. As you said, it has been
        often stated to be one of the best 4" apos ever made if not THE best. Buuuut if
        you don't use it much for visual you might be better served with a faster
        scope. But then again you could use a focal reducer on the TMB. I personally
        don't care much for really short F refractors but the majority of use mine have
        seen has been visual. A lot of EPs start showing signs of lateral color with
        the shorter focus apo refractors. And the shorter you go the worse it gets.
        Put a 41 Panoptic in an F6 and look at the moon off axis and you'll see what
        I mean. Looks like someone took a tricolor image and didn't merge it
        correctly. Even my F7s do this with that EP. And as you have found, the longer F
        creates a longer radius of field curvature eliminating the need for a flattener.
        Well, almost. You do have a little corner stretch there in your M42/Running
        Man shot but it's not as much as I expected. Truly hardly noticeable. My F7 6"
        and 30D produce more corner stretch than that without the flattener and I
        would have to think that it has a longer radius of curvature. Nice shot BTW.
        Did you crop it?
        A modded DSLR might reduce your exposure times by letting more of the
        red H, N and S emisions through but not having modded my Canon I'm not sure.
        Just curious, why do you want to downgrade from the 20D to a Rebel? I'm
        assuming that you use a Canon TC (timer controller)? Are you aware that it won't
        plug into a Rebel without modifying the plug? Of course the cost of modding the
        plug plus the camera might still be less than a 40D.
        Anyway, I hope this helps you alleviate any buyers (traders) remorse
        about the TMB.

        CS,
        David
        **************From Wall Street to Main Street and everywhere in between, stay
        up-to-date with the latest news. (http://aol.com?ncid=emlcntaolcom00000023)


        [Non-text portions of this message have been removed]
      • Jerry Brown
        Paul, These are beautiful images. I would keep it, maybe invest in a FR. I nearly obtained one of these recently (the deal fell through) and was concerned
        Message 3 of 7 , Feb 1 9:32 AM
        • 0 Attachment
          Paul,
          These are beautiful images. I would keep it, maybe invest in a FR.

          I nearly obtained one of these recently (the deal fell through) and
          was concerned about the same issue. I ran across a paper by Craig
          Stark discussing F ratio and exposure time. He contends that as long
          as the image collected is above the noise floor, the f ratio is not
          important when it comes to image quality. The relationship between f
          number and exposure time was driven by nonlinearity in film. Aperture
          vs exposure time is the more appropriate thing to trade.

          http://www.stark-labs.com/blog/files/tag-ramblings.php

          I would not push someone elses research, except I have a great deal
          of respect for Craig Stark's opinion

          I hope it helps,

          Jerry


          --- In tmboptical@yahoogroups.com, "madpc" <madpc@...> wrote:
          >
          > Hi All,
          >
          > Until recently I had been using an Excellent William Optics FLT-98
          When a
          > TMB 100 F8 come up on offer for a swap so I did this.
          > This is the Model reviewed by David Novoselsky on Cloudy nights: -
          > http://www.cloudynights.com/item.php?item_id=462
          >
          > This was reputed to be one of the best 4" APO's ever made.
          >
          > I have recently taken the following pictures with it: -
          > http://www.madpc.co.uk/TMB-100/Copernicus-06-01-09.jpg
          >
          > http://www.madpc.co.uk/TMB-100/M42-19-12-2008b.jpg
          >
          > http://www.madpc.co.uk/TMB-100/Moon-06-01-2009.jpg
          >
          > The Scope delivers a dark background with great contrast so much of
          what the
          > review says is true.
          > This one has the violet coating.
          > Another good point is I don't need a reducer / flattener for my 40D
          as the
          > stars are sharp to the edge.
          > The bit I do miss about the FLT-98 is its faster at F6.3 (Near F5.5
          with the
          > TV reducer flattener) So this seems to allows more light gathering
          powers
          > for 5-6 min exposure.
          > To get the same amount of data of the 40'd sensor with the TMB
          means 8 to 10
          > min exposures.
          > This is all well and good if my skies would allow such long
          exposures
          > regularly.
          > In reality they don't.
          > In some ways I regret letting the FLT 98 go but in other I do not.
          > I suppose the question is do I let the TMB go and get another FLT
          98 or do I
          > persevere with the TMB...
          > I'm sure it has loads to offer.
          > Oh I'm getting a modified Canon 1000D so this might help??
          >
          > Regards,
          >
          > --
          > Paul Gordon
          > paul.gordon4@...
          > http://www.madpc.co.uk
          >
        • madpc
          HI David, No the image was not cropped.. I didn t downgrade as such I brought the 1000D as it performance was similar to the 40D for Imaging (I didn t want to
          Message 4 of 7 , Feb 15 3:07 PM
          • 0 Attachment
            HI David,



            No the image was not cropped.. I didn't downgrade as such I brought the
            1000D as it performance was similar to the

            40D for Imaging (I didn't want to modify my 40D but keep it for daytime
            photography.



            I don't use the Canon TC with the Camera for Astro photography just a laptop
            and live view.



            Regards,

            --

            Paul Gordon

            madpc@...



            From: tmboptical@yahoogroups.com [mailto:tmboptical@yahoogroups.com] On
            Behalf Of dthorman1@...
            Sent: 30 January 2009 07:33
            To: tmboptical@yahoogroups.com
            Subject: Re: [tmboptical] Advice on TMB 100 F8



            Hi Paul,
            My Dad has a TMB 100/800 Classic I am quite impressed with though he
            doesn't use it for imaging. I don't have any experience with an FLT 98 but
            even
            then I am inclined to advise on keeping the TMB. As you said, it has been
            often stated to be one of the best 4" apos ever made if not THE best. Buuuut
            if
            you don't use it much for visual you might be better served with a faster
            scope. But then again you could use a focal reducer on the TMB. I personally

            don't care much for really short F refractors but the majority of use mine
            have
            seen has been visual. A lot of EPs start showing signs of lateral color with

            the shorter focus apo refractors. And the shorter you go the worse it gets.
            Put a 41 Panoptic in an F6 and look at the moon off axis and you'll see what

            I mean. Looks like someone took a tricolor image and didn't merge it
            correctly. Even my F7s do this with that EP. And as you have found, the
            longer F
            creates a longer radius of field curvature eliminating the need for a
            flattener.
            Well, almost. You do have a little corner stretch there in your M42/Running
            Man shot but it's not as much as I expected. Truly hardly noticeable. My F7
            6"
            and 30D produce more corner stretch than that without the flattener and I
            would have to think that it has a longer radius of curvature. Nice shot BTW.

            Did you crop it?
            A modded DSLR might reduce your exposure times by letting more of the
            red H, N and S emisions through but not having modded my Canon I'm not sure.

            Just curious, why do you want to downgrade from the 20D to a Rebel? I'm
            assuming that you use a Canon TC (timer controller)? Are you aware that it
            won't
            plug into a Rebel without modifying the plug? Of course the cost of modding
            the
            plug plus the camera might still be less than a 40D.
            Anyway, I hope this helps you alleviate any buyers (traders) remorse
            about the TMB.

            CS,
            David
            **************From Wall Street to Main Street and everywhere in between,
            stay
            up-to-date with the latest news. (http://aol.com?ncid=emlcntaolcom00000023)

            [Non-text portions of this message have been removed]





            [Non-text portions of this message have been removed]
          Your message has been successfully submitted and would be delivered to recipients shortly.