SharpStar FAQ

SharpStar2 precision focusing tool for astrophotography by Lonely Speck

All information on this page applies to both SharpStar2 and the original SharpStar design, unless otherwise noted.


Where can I order?

SharpStar is currently only available via the Lonely Speck website.

Order SharpStar2 (our latest design) here. The original SharpStar design has been discontinued but you can find more information about it here.


How do I use the SharpStar?

Check out our short video tutorial about using the SharpStar2 in the field:

The SharpStar2 is shown in the video above. The original SharpStar works the same way.

You can also download a copy of our Quick Start Guide (included with every order).


Why is my SharpStar2 not working? Why is it covered with paper?

If you can’t see any stars (or anything at all) through the SharpStar2, you might still have the factory paper backing applied. Your StarpStar2 may arrive with a layer of paper that protects the SharpStar during the laser manufacturing process and helps protect the surface of the SharpStar during shipping.

sharpstar2-bahtinov-astrophotography-focusing-mask-1 copy

To remove this layer, use your fingernail to gently separate the paper from the SharpStar2 at a corner, then slowly peel the paper away. Gently remove any remnants in a similar fashion. When the paper is completely removed the SharpStar2 should appear clear and transparent, like glass.


I’m having trouble seeing the diffraction spikes in my images.

In order to get the best results from the SharpStar2, there are a few things that may help:

  • Keep the SharpStar2 centered on the filter holder. Depending on the lens, the SharpStar2 may be sensitive to centering. If the SharpStar2 is off center, not all of the diffraction spikes may be visible. Shorter lenses (wide angle lenses) are the most sensitive to centering.
  • Always center a bright target star (or planet) in the frame. The closer the star is to the center of the frame, the better the results.
  • Dark skies make the best results. If the moon is full, contrast in the sky can be diminished and the SharpStar2 may not produce as pronounced of diffraction spikes.
  • If you’re still having trouble, please feel free to contact us.


Which lenses is the SharpStar compatible with?

SharpStar2 Compatibility

SharpStar2 was designed to work on most DSLR and mirrorless system camera lenses.  As with most wide field astrophotography, SharpStar2 will usually show the best results from relatively large-aperture, or “fast” lenses. The shorter the lens, the smaller the diffraction pattern and the more careful you’ll need to be to center your target star in the viewfinder.

See our SharpStar2 lens compatibility chart below:


In general, the lower the f/number and/or longer the focal length of the lens, the better (e.g. it won’t work well on a 10mm f/3.5 but will work well on a 12mm f/2).

Please note that the focal lengths and f/numbers marked on this chart are the ‘true’ focal lengths and f/numbers. Use the numbers marked directly on your lens, NOT the 35mm equivalent. That means that you should NOT multiply focal length by your camera’s crop-factor before checking the chart.

To demonstrate why higher f/numbers aren’t as good, check out the examples below of the diffraction spikes made with the SharpStar2 on a 16mm lens at different f/number settings:

SharpStar2: Example Diffraction Spikes with 16mm Lenssharpstar-f-number-example

As the f/number increases, the size and visibility of the diffraction spike pattern diminishes. The central spike at f/5.6 is still barely visible, bit it’s a little too difficult to see for us to recommend as a focusing aid. Use the SharpStar2 at lower f/numbers for the best results.

Which filter holder(s) do you recommend?

To mount a SharpStar you will need:

  • a square filter holder system compatible with your lens
  • adapter ring compatible with your filter holder system and your lens filter thread diameter

To determine which size filter holder system and which adapter ring you will need, you will need to know your lens’s filter thread diameter. The filter thread diameter is usually marked in millimeters on the front of your lens with a diameter (⌀) symbol like this:


In this example, the lens shown has a filter diameter of 49mm. Depending on your lens’s filter diameter size, we recommend the following systems. In general, pick the system size that’s larger than the thread diameter of your lens and also purchase an adapter ring that matches your lens’s thread diameter.


Will the SharpStar fit a fixed hood lens like the Nikon 14-24mm/2.8 or the Rokinon 14mm/2.8?

A new 150mm size is now available for specific fixed hood lenses. Please see our order page for more information.


Do you ship outside the USA?

Yes, orders for the SharpStar2 can be shipped internationally. Shipping fees vary by country.

Our international orders are shipped via USPS First Class Mail. Shipping speeds vary and may take 2-3 weeks to arrive. Tracking may or may not be available depending on the destination. As the buyer, you are responsible for any import taxes (VAT, etc.), duties, and customs fees that your country may impose at the time of receipt of the shipment. All international shipments are marked on the customs form as “Merchandise” with an accurate description of the value and contents (e.g. “Photographic Filter”) and labeled with the proper six digit HS tariff code for photographic filters: 900220. Please check with your local postal service for status updates on your order once it has left the USA.

For further questions, just ask in the comments below or contact me directly. -Ian

195 Replies to “SharpStar FAQ”

  1. To whom it may concern,

    I bought the following items on your website two months back, for my mother’s birthday present.

    Line Items:
    1x SharpStar2 by Lonely Speck for $64.00 each
    1x Premium Filter Case by Lonely Speck for $12.00 each
    85mm filter case

    The order number is (#103098694).

    Today (March 21, 2019), I opened the box and tried to put the ordered Sharpstart 2 filter (85mm) into my Cokin filter holder; but the size of filter didn’t match well with my own filter case (which has to be well fitted). So, I measured the size of the filter produced by your company and found out that the size of filter is smaller than the specification indicated in your website. It shows 83 mm length.

    I look forward to hearing from you soon.

    Patrick Kim

    1. Hi Patrick, our SharpStar2s are made to a measurement of 84mm +/- 0.5mm which allows for universal fit in Cokin P, 84mm and 85mm filter holders. They are marked 85mm because that is the most common industry moniker for this type of filter. If your filter does in fact not fit in your Cokin P holder, please email me at [email protected] and we can set up a replacement promptly.

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