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Dall-Kirkham mirror sets for sale

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38 replies to this topic

#1 Tavi F.

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Posted 04 November 2017 - 03:12 PM

Hello,
The first two DK mirror sets that I have for sale are of 135mm aperture, the so called type 1. The rest of the main parameters being described below:
- D=135mm - useful diameter;
- Fech=3600mm - the system focal length (F/26.7);
- h=489.3mm - the separation between the mirrors;
- e=175mm - back focus;
- d2=28mm - secondary diameter (20.7% linear central obstruction).

All these mirrors are handmade and diffraction limited. In my estimation of ~L/8 wavefront (at the eyepiece) and a Strehl Ratio at least 0.94. They gives excellent images. In this presentation I will show you the Ronchi star test for each set. Outside focus, with 0.1mm wire screen.

 

rssr9h.jpg

 

281d99i.jpg

 

Price for one set = 150 euro (+shipping and PayPal fee)

 

More information in PM.

Thanks!


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#2 Tavi F.

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Posted 01 December 2017 - 09:04 AM

A super offer applied to the already small price, available only this month.

 

Effective price for one set of mirrors = 120 euro.



#3 Ovidiu Catalin

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Posted 23 December 2017 - 06:26 AM

Great optical performance Tavi good job, i love your DK set good luck on your next series of mirros and have a nice sale.


Edited by Ovidiu Catalin, 23 December 2017 - 06:29 AM.


#4 Tavi F.

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Posted 19 April 2018 - 04:59 AM

The lowest price for these sets is 100 euro/set. For unlimited time.



#5 Tavi F.

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Posted 04 May 2018 - 11:28 AM

In our astro community, on a local amateur forum, there was an "aperture fever" among the observers of the sky. And that attitude was stimulated by some commercial interests from another mirror maker (with his entourage), which have been lucky enough to get in the possession of more advanced manufacturing devices... to make larger, more profitable mirrors. A long the way, that mirror maker have stated that the telescopes smaller than 150mm in aperture have no use in planetary observation!! Which is, at least, a unfortunate statement.
That "aperture fever" might be world wide. So, for this reason, I mounted in my telescope one of these Cassegrain mirror sets, of 135mm aperture and 3600mm focal length. In fact, the f.l. is more towards 3800mm, because the larger extension induced by the focuser. To see exactly and judge for yourself how much details are in these mirrors. The telescope is closed and the mirrors well preserved.

 

2lc69p0.jpg

 

For the moment, here is one capture of the Moon, close-up of course (170 frames stacked):

26967534977_b1c17408a8_o.jpg

 

For the photo recording, I am using a Canon 550D. More to come.



#6 Tavi F.

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Posted 09 May 2018 - 02:04 AM

More pictures from the 25th last month:

 

41016967275_1bfa842bbe_o.jpg

 

27116584287_1a8bed2402_o.jpg



#7 Tavi F.

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Posted 31 May 2018 - 02:11 AM

Jupiter from the night of 28th to 29th May. 1000 frames. Altitude: 28 and 30 degrees. Seeing: just above average.
Not quite bad, ha? I would say it probably worth to build a compact and light Cassegrain telescope with these mirrors.

 

42417924312_c07dd35b27_o.jpg


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#8 Tavi F.

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Posted 05 June 2018 - 09:49 AM

And another capture on good seeing. 1100 frames stacked.

 

40762388740_8f76b4d966_o.jpg


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#9 GlenM

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Posted 05 June 2018 - 04:03 PM

Absolutely stunning images. Very much a pleasure to look at.

 

Glen.



#10 Tavi F.

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Posted 10 June 2018 - 07:33 AM

Thanks, Glen!

 

80 euro effective price for one set. 150 euro for both sets. The lowest price you can look for!

 

Here is another image from the end of May, with the transit of Europe. 1000 frames stacked. The seeing conditions were average or just above, but the details are quite nicely.

 

41775195424_a1f876045e_o.jpg



#11 GlenM

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Posted 10 June 2018 - 08:42 AM

Another very good image, thank you.

 

Glen.



#12 Tavi F.

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Posted 16 July 2018 - 04:48 AM

Hello,

A few more lately images.

 

1. Jupiter towards the end of the season:

 

- 2018-07-03:
41456155570_b9f959ff4d_o.jpg

 

- 2018-07-11:
42479199545_d8fe715ccd_o.jpg

 

2. Venus, 2018-07-05:

42425824515_38ff682c25_o.jpg

 

3. Mars

 

- 2018-07-04:
43239173771_a0cce29c6a_o.jpg

 

- 2018-07-12:
43376993532_ece79c2055_o.jpg

 

All of this was possible thanks in part to my trusty ADC wedge disc, shown in the following threat: https://www.cloudyni...-adc/?p=8541924

 

I still have to process an image of Saturn. And with that, in hope of a clean-up in time for the great opposition of dusty Mars, I will consider the promotion of these mirrors to be complete. Thanks.


Edited by Tavi F., 16 July 2018 - 04:50 AM.


#13 netwolf

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Posted 16 July 2018 - 04:54 AM

Tavi I am interested sent you a PM. 



#14 GlenM

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Posted 16 July 2018 - 08:02 AM

Stunning,just stunning Tavi.

 

Glen.



#15 Tavi F.

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Posted 19 July 2018 - 02:45 PM

And as I said in the previous post, here is one more image with Saturn from July 12th, 24 degrees altitude:

 

28611888837_8a07a94890_o.jpg

 

Capture taken with that ADC disc of personal use (2 degrees), of course, and it wasn't needed any touch of RGB alignment in post-processing. All being done from optical correction.


Edited by Tavi F., 19 July 2018 - 02:46 PM.


#16 Tavi F.

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Posted 21 July 2018 - 02:29 AM

Update: One set of mirrors was sold. One is still available. Thanks!



#17 Tavi F.

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Posted 05 August 2018 - 03:20 PM

Update: -  A new set of DK mirrors comes in (the "M5" primary mirror). It is also of 135mm aperture at the same parameters as the first two sets, but at even better optical quality. The effective price for this set is 130 euro (fixed price), which is still cheap for his quality.

 

- The "M2" set from the first series remains at 80 euro, effective price.

 

- Apart from these, I still have two sets of uncoated mirrors for the moment. I will send them for coating as the selling progresses. These are also at the M5 quality and will be at the same price, 130 euro.

 

- I will attached the star test for the current "M5" set in a week or two, when I will install these new mirrors on the testing telescope (just for the star test).

Thanks.

 

10wsg9z.jpg

 

 



#18 Tavi F.

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Posted 08 August 2018 - 01:45 PM

And with this image from 5th August, the promotion of the DK D135mm mirror sets is complete.

The general seeing was at most at average level, the planet actually jumping wildly in the field. But the turbulence was of that type which had been allowing fractions of seconds with good focused images.

Just 1300 frames stacked. 19 degrees altitude for Mars in my location.

 

43025591765_6907c0718d_o.jpg

 

Thanks.



#19 Tavi F.

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Posted 14 August 2018 - 02:36 AM

Hello again,

 

This is the stat test for the M5 mirror set. 130 euro effective price for this set, as I said before.

 

11k9so7.jpg



#20 Tavi F.

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Posted 18 August 2018 - 03:22 PM

Update: The M2 set was sold and the M5 set is reserved to someone from India.

 

Most probably, next month I will send another set of this type of DK mirrors for coating, from the last two available.

 

Thanks.



#21 Tavi F.

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Posted 22 August 2018 - 05:06 AM

Rectification of the previous post: The M5 set is up for grabs, if someone wants to buy it sooner than "mid September to mid October". An excellent performer at a low price, for easy portable Cassegrain telescope.

 

Thanks.



#22 Tavi F.

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Posted 16 October 2018 - 04:36 PM

Hello, here is an update:

 

The M5 set from the D=135mm series was sold. More to come in the next days.

 

A new set of DK mirrors is available, the first one of the new series. The parameters of the system are:

- D=170mm (useful aperture);
- d=36mm, the diameter of the secondary;
- Fech=4400mm, effective focal length;
- h= 650mm the mirrors separation;
- e=190mm the back focus.

 

2zi9644.jpg

 

This is a great telescope for planetary work. The lowest selling price for the mirrors set is 250 euro (+shipping and PayPal fee).

And here is an image of Mars, taken on October 10th, with these mirrors mounted on the testing scope + an ADC disc + DSLR Canon 550D. 14".4 angular size of Mars, being at 24 degrees altitude. 2200 frames stacked.

 

30391428397_8812158e99_o.jpg

 

Thanks.



#23 Tavi F.

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Posted 21 October 2018 - 07:15 AM

Update on the last two DK mirror sets of 135mm aperture type. These are excellent performers, with a Strehl Ratio of list 0.95 at the eyepiece in my estimation, which correspond, of course, to the diffraction limited criterion. 

The price for one set is back to the original: 150 euro (+shipping & PayPal fee). And it will be the lowest selling price. I still think the mirrors are quite cheap; they could easily go to 200 euro or above from other manufacturers.

 

wk4kte.jpg

 

nnl9us.jpg

 

And an image of tiny Mars (13".8) taken at the end of that testing evening:

 

45442547581_e9267f88c1_o.jpg



#24 Tavi F.

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Posted 04 November 2018 - 01:31 PM

Update: You can find more images taken through the larger DK mirrors in discussion, the D170mm ones, in the following topic:

https://www.cloudyni...pe-d170mm-f259/

 

I was making three sets, but for the moment I have just one primary finished. The other two still require some work to put on them the final aspheric shape... but probably I will resume the work on them next year, towards the summer.


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#25 Tavi F.

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Posted 06 December 2018 - 09:25 AM

Hello,

 

Update: The larger set of mirrors (D170mm) was sold to someone in my home country. Hopefully, I will have another one of this type available by June 2019.

 

The other two exposed here (of 135mm aperture) are still available.


Edited by Tavi F., 06 December 2018 - 09:27 AM.



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