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Handmade refractor objectives

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3 replies to this topic

#1 Tavi F.

Tavi F.

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Posted 20 September 2021 - 02:13 PM

Hello,

 

A few notes about my achromatic objectives domain:
- all will be Clark type (echiconvex crown);
- all will use dense flints, from the N-SF range on the Schott diagrame. This means that the residual coma will be minimal to basicly fully corected.

PS: - the lenses (these and the future ones) are not coated. /PS

 

1. The first objective I have to prezent here is from the 100mm useful aperture:
- D=100mm
- Db=107mm (the total lens diameter);
- F=1200mm (focal length).
- 522nm-C colour correction, that means photographicly, it has been design to be a great one using a deep yellow filter. And visually, just one colour (blue) hallo, around bright objects, the so called „planetary correction”, but a very pale, not harmfull blue. In my oppinion, this is a better colour correction for achromats.
With any doubt, it is a difraction limited objective. You can see the double pass (autocolimation) test below.

 

51496164402_f3befd734e_h.jpg

 

Because the flint lens stil have a crack on the edge from the original lens regrounded now by me, I cutted off some money from the price I would ask for a similar objective made from raw glass. But this crack have no effect on its functionality, it is not even in the useful aparture. The crown glass is perfectly intact.

  

Price (for the lenses and the ring): 150 euro + shipping.

This is just a small price for the optical excellence!
More info in pm. Thanks.


Edited by Tavi F., 20 September 2021 - 05:06 PM.

  • zjc26138, Rollo, ngc7319_20 and 1 other like this

#2 Tavi F.

Tavi F.

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Posted 20 September 2021 - 05:07 PM

Update: The objective is reserved to someone from India.

 

PS: About the coatings. I have made for my self another doublet objective (D78mm, F1200mm) back in 2013. It is also uncoated, with no gost images. I would suggest not to coat the lenses. The coating process implies some risks and I don't want to get involved in this. The quality of the images does not relay on the coatings.


Edited by Tavi F., 21 September 2021 - 12:06 PM.


#3 Tavi F.

Tavi F.

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Posted 01 October 2021 - 11:40 AM

Update: The objective was sold. It is going to India.

 

I would like to keep the topic open, to add here some other announcements for similar products, over the years.
Thanks!



#4 Tavi F.

Tavi F.

    Vendor (refractor optics)

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Posted 13 October 2021 - 01:38 PM

At the following link is an update related to this subject as well:

 

https://www.cloudyni...ale/?p=11426646




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