168 replies to this topic

[a__l]

Had the same issue with my Fujinon 25mm F/0.85. Fully screwed in, infinite was abouy halfway through the lens’ focus range. Ended up wrapping some sewing thread around the bottom of the threads to “tune” it to infinite, about a millimeter. Works great now.

I suspect the infinite point is out a bit to account for the waterproofing O ring on the ENVIS lens. Mine seems to be spaced out a bit when seated properly on my Mod3c. So many be that it?

I write a little about something else. Narrow lens adjustment range. When make adapter it is necessary to maintain a distance to the sensor.

As for mod3. My NV uses a different body. This is Katod Inc. Distance to sensor ~ 10.5 mm, hole diameter 28 mm min. The battery compartment is upside down. With this body, I have more free choice. For example, 2 inch nose for paracorr through M42 with an open hole of 28 mm (photo).

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Edited by a__l, 18 June 2020 - 04:28 AM.

[a__l]

Tevidon for afocal use. The most difficult part is the teflon ring. I made 5 rings. The latter was made, as expected. The ring is bronze, 2 attempts. Big and thin. It is difficult to make a thread.

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Edited by a__l, 19 June 2020 - 05:21 AM.

[a__l]

Today gave the stars. Tested Tevidon in 1x mode. Works good. Visibly vignetting, approximately 10% of the edge. Corrected on the edge better than the complete Katod lens.
In afocal mode. Tevidon alas ... The lens is deeply recessed. Large  cut off (for N31). The complete Katod lens (similar to Envis, photo) works well in afocal mode. But he has a problem, there is no thread to fasten to the adapter. To use afocal mode I will think ....

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Edited by a__l, 19 June 2020 - 08:47 AM.

[a__l]

Actually, the fastest idea came to my mind. Use the sacrificial adapter 2-> 1.25 "
Outside, cut M50x0.75 thread under a bronze ring (photo above on N31). Cut 0.5 mm inside the adapter. Cut off excess length. Everything else is perfect.

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[a__l]

Afocal use. Lens Katod. Now everything should work

 

Katod Features

F/1.25

Field of view 40 degrees
Weight 80 g

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Edited by a__l, 22 June 2020 - 12:55 AM.

[a__l]

The rings came from China. Photo Zeiss Jena DDR Tevidon 25mm f/1.4 complete with H-alfa filter. Good lens

 

My NV build project is completed. I did everything I planned for observant NV.
For my 3 dobs 2" prime focus with and without paracorr (28 mm hole), Powermate-2x, it is possible to quickly switch to the visual use of eyepieces-filters, afocal with Nagler-31 (I have no other eyepieces of a larger focal length) with and without paracorr, 2 lenses 25 mm Tevidon and 75 mm Fujinon with 2" filters (H-alfa and 685nm or without them). It took ~ 3.5 months. Now only observations.

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Edited by a__l, 27 June 2020 - 04:43 AM.

[a__l]

Today gave the stars.
Alas, the process is not over. The inner diameter of the glare shield (57 mm) was small for Tevidon. I counted it for the Fujinon-CF75HA-1. Vignetting edge. We must buy another with a significantly larger diameter.

[GeezerGazer]

...or, reduce the length of the existing shield!  If you are at dark skies, you should not need the shield at all.  A shield is really only needed for a direct light source in the direction you point your NVD.  I found in tests that a short light shield is all that's needed most of the time.  I am surrounded at home with streetlights.  One light shield I made extended only about 1cm in front of my Envis lens and was sufficient to come within about 5° of a street-light without effect.  Here is a link to read about my tests and see images of results: 

https://www.cloudyni...e#entry10119001

 

Edit:  I see you already visited that thread this year.  BTW, your machine work is inspiring! 

Very nice indeed.  

Edited by GeezerGazer, 05 July 2020 - 02:12 AM.

[a__l]

Today came another package with Aliexpress.
I want to specify. Rise (UK) ring 35.5-37 mm good connection with the lens. Therefore, if you find a Zeiss Jena DDR Tevidon 25mm f/1.4 with c-mount, you should have no problems with this lens.

Edited by a__l, 05 July 2020 - 03:57 AM.

[a__l]

This diameter is sufficient.

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[sixela]

I, too, would like to applaud Eddgie's post regarding vignetting.  Some time ago I acquired a Cosmicar 25mm f/1.4 lens to use with my Collins I³ image intensifier.  I first attached it to my NVD Micro in place of the ENVIS lens.  While both lenses have the same diameter opening for the back element, the Cosmicar does not protrude into the body of the device as the ENVIS does.  Consequently the view of the night sky was highly vignetted.

[Digging this up from the grave]

That's bizarre -- I'm currently using a Cosmicar 25mm f/1.4 for 1" sensors with very little vignetting on my OVNI-M in the first 16mm (there is indeed hard vignetting of the last millimeter, but frankly having 38° AFOV rather than 40° does not bother me). It does sit closer to the sensor by 2mm to have infinity focus where it is supposed to (I have to focus in the middle of the range). That makes me think you have the 2/3" sensor one.

[AllStarez]

[Digging this up from the grave]

That's bizarre -- I'm currently using a Cosmicar 25mm f/1.4 for 1" sensors with very little vignetting on my OVNI-M in the first 16mm (there is indeed hard vignetting of the last millimeter, but frankly having 38° AFOV rather than 40° does not bother me). It does sit closer to the sensor by 2mm to have infinity focus where it is supposed to (I have to focus in the middle of the range). That makes me think you have the 2/3" sensor one.

Hi Sixela

please could you post a picture of your lens ?

[sixela]

This one:
https://www.benl.eba...tm/275052188671

[Yes, it has no filter threads, so you have to jury rig it to get filters on top of it]

Probably the same as:
https://www.benl.eba...tm/175295881536

It's got a fairly wide flat lens at the back, going almost all the way to the C-mount inside, recessed roughly 4mm; you need to insert some flocking next to it to hide the shiny C-mount barrel. I've seen others with a much more narrow back lens and they vignetted HARD.

Edited by sixela, 02 September 2022 - 05:55 AM.

[AllStarez]

Thanks 

I did try a few 25 mm lenses with no success, I’ll give a try on that one

[sixela]

The last mm of the 9mm sensor radius or so is vignetted iirc, but I don’t find that too bothersome.

Edited by sixela, 02 September 2022 - 04:39 PM.

[a__l]

When it comes to using an afocal lens with TV67. I tested several good lenses for this, spending a decent amount of time on this.
Zeiss Tevidon, Nikon Nikkor and PVS-14.
And I came to the conclusion that the latter is the best. It should be noted that there are several such lenses from different manufacturers. They are of different quality. My latest from Fujinon. A very successful lens.

[yemingxp]

When it comes to using an afocal lens with TV67. I tested several good lenses for this, spending a decent amount of time on this.
Zeiss Tevidon, Nikon Nikkor and PVS-14.
And I came to the conclusion that the latter is the best. It should be noted that there are several such lenses from different manufacturers. They are of different quality. My latest from Fujinon. A very successful lens.

May you sir show us the specific model of the fujinon one? Thanks.

[a__l]

Housing and lens coating shown here (here it looks like a photo of Carson):

https://www.cloudyni...ale/?p=12342383

My lens has an earlier marking (Fujinon).

Ps. If you look closely they are all different. For example Fujinon (Carson) has one row of stripes. There are two dot marks on the ring on the back.

 

With two adapters shown here:

https://www.cloudyni...ale/?p=12343803

 

(#69 post, CN engine crashes?)

Edited by a__l, 21 December 2022 - 07:06 AM.

[sixela]

May you sir show us the specific model of the fujinon one? Thanks.

Really easy -- it has onely one knurled ring at the top and very typical blue coatings.

 

The "fun" thing is that many sites are actually selling different ones with a picture of that one on the web page.

 

E.g. https://www.agmgloba...e-lens-assembly shows a Fujinon -- but what you're getting most definitely comes from Optronics Engineering in Israël (although the quality of the coatings has improved somewhat).

Edited by sixela, 21 December 2022 - 09:44 AM.