Pier 4

Sigma Art 105mm f/2 Ultra-Widefield Lens

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Sigma 105mm F/1.4 ART lens stopped down to F/2, when combined with the ZWO ASI-071MCC OSC APSC sensor this has a crop factor of 1.5 which gives an effective focal length of 157mm.

We could use this lens wide open but stopped it down because of potential filter bleed issues as well as it tightens up the corners a small amount, it’s an exceptionally well corrected lens that will deliver stunning detail that requires ridiculously short exposures.

Pier 4 runs totaly unguided, we have only fitted a guide camera to cover murphy's law :)

CMOS Camera

Just in case you have never used CMOS and have been using CCD like the rest of us for the last million years then let me tell you it requires a different approach, you can forget long subs as the are not needed and at most times detrimental to your image quality. Allowing for CMOS’s sensitivity, higher dynamic range and super low read noise broadband imaging typically 30/60s  and 120s is more than ample enough for narrowband, you just needs a lot more of them of course.

For your convenience and ease of use we have taken the time to calculate this setup for filter weightings which if followed will help you to maximise your imaging time. For more information on this visit out FAQ's page.

The ZWO ASI-2600MC Pro Colour CMOS is one of Sony's new generation zero ampglow sensors, so no need to worry on that count :)

This camera is set to Unity Gain as our default, if you have any special gain and offset requirements for CMOS imaging please discuss and we will do our best to accommodate you.


Sigma 105mm f/1.4 @ f/2


ZWO ASI-2600MC Pro Colour


Astro Physics AP900

  • Telescope

    Sigma 105mm f/1.4 @ f/2

  • Camera

    ZWO ASI-2600MC Pro Colour

  • Mount

    Astro Physics AP900

Equipment List

Sigma 105mm F/1.4 Art Lens Stopped down to F/2
Astro Physics AP900 GTo3
ZWO ASI-2600MC Pro Colour CMOS 1x1 Binned
Filter Wheel
Guide Camera
ZWO ASI-120 Mini - 1x1 Binned (Back-up not used)
ZWO Mini Guide Scope
Astromechanic Lens Focusing System
Power Control
HitecAstro MHP V4

Sony IMX571

CMOS Sensor


  • 12.82° x 8.57°

  • 7.39 "/px @ 1x1 Binning

  • 105mm Focal Length

  • F/2

  • 20º Imaging Horizon Limits

  • Recommended sub lengths

Broadband Imaging



  • Imaging subjects with brighter cores will of course require shorter sub lengths for HDR, your personal experience will be needed to gauge this yourself.

  • Please remember this is only a guide above, we are just trying to help you have the best experience possible remote imaging with Roboscopes.

  • Although we have taken Bias frames we do not recommend using them with CMOS sensors.

  • Roboscopes supply the site and control the equipment but you choose everything else from filters, object/co-ordinates to sub lengths. So you need to exercise due diligence and experience when booking because if you fill the booking form out with incorrect details then you will get precisely that.

  • It is not Roboscopes responsibility to check your detailed requirements after you have booked. Basically garbage in garbage out!!

  • Filter weights

Get accurate star colours with recommended colour balance







Calibration Files

The following calibration files are available as standard with this system. Other darks are available upon request.

  • 10s Darks

  • 30s Darks

  • 60s Darks

  • 120s Darks

  • 150s Darks

  • Bias Frames

  • Flat Frames

Field of view examples

Image courtesy of Roboscopes member Mark Large
Rho Ophiuci taken with Pier 4

Image courtesy of Roboscopes member Mark Large

Image courtesy of Roboscopes member Simon Downing
NGC-7000 Widefield Pier 4

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802 Kingsbury Road
B24 9PS
United Kingdom

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