Here is the detailed presentation about the prime-focus astrophoto performances of our 102mm f/7 triplet SD apochromat objective lens unit (optional item of BINOKIT - OBJ102SD-Triplet.)

JPY138,000/pc (JPY151,800/pc incl. 10% Consumption Tax)


This 102mm f/7 triplet SD apochromat objective lens unit (mentioning "new objective lens" hereafter) was originally developed mainly for visual use, but it can yield very high performance for prime-focus astrophoto use, too. Our contracted astrophotographer has tested this new objective lens practically, and he gave us a detailed report with several photos proving the excellent performance, as well as the tips for the useful combination with BORG components. Shown as below.

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About a focal reducer

A focal reducer is essential for astrophotos with this new objective lens. This time BORG focal reducer 0.72xDGQ [7872] was used, as it's a current model and used by many BORG owners. As a result, it's the very best match with our new objective lens. And, as it becomes f/5 (f.l. 514mm), it's also quite recommendable as an upgrading option from BORG 90FL or 71FL

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Full-frame image

The full-frame image with new objective lens + BORG 0.72xDGQ focal reducer. Click to enlarge (to actual pixels.) Check both central and edge star images.

Objective lens: BINOTECHNO's 102mm f/7 triplet SD apochromat objective lens unit
Focal reducer: BORG focal reducer 0.72xDGQ [7872]
Camera: Canon full-frame size digital camera
Explosure: 5min.
Image processing: only Dirk correction, Level correction, and Digital development (no Flat correction and no Sharp processing)

Astrophotographer's comment: It's quite possible to take excellent full-frame astrophotos with this combination. Highly recommended for present BORG users. Precisely examining the image, the stars at the left corner are a bit deformed, but it's caused with various factors and the extent of the deformation is very little that is never found up to A4-sized print. Also the edge darkness is a little prominent and the bright star images at the very edge are cracked just a bit. Still, the edge darkness itself can be compensated by flat frame processing, so it's not a serious problem at all.

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Example image

Another spectacular image with the same combination (with a different camera.) Click to enlarge (to actual pixels.)

Objective lens: BINOTECHNO's 102mm f/7 triplet SD apochromat objective lens unit
Focal reducer: BORG focal reducer 0.72xDGQ [7872]
Camera: Four Thirds Cooled camera
Filter: SVBONY LRGB filter(No Light Pollution Reduction filter used)
Explosure: L=5min.x63, R=5min.x18, G=5min.x18, B=5min.x21 (Total 10hours)

Astrophotographer's comment: Very best match with BORG Focal Reducer 0.72xDGQ. This new objective lens is really wonderful as original BORG objective lenses.

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Combination Examples with BORG Components

The combination of BORG components when the above photos taken is following (from the rear end of the objective lens):

80dia. L135mmtube [7138]

M77.6 to M68.8AD [7801]

Helicoid M [7835]

M57 Rotary device DX [7352]
If not used, M57/60 Extension Tube SS [7601] or other equivalent extension tube is necessary instead.

BORG focal reducer 0.72xDGQ [7872]
Remove Spacer S (as it's only for 90FL.) Also attach Spacer L when Filter BOXn is not used.

Filter BOXn [7519]

M57 to M49.8ADSS [7923]
This is necessary to reduce the backfocus when 0.72xDGQ is used with the new objective lens.

Camera Mounting Ring (for each brand)
Camera Mounting Holder M [7000]is not necessary.

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