hha

The diffraction pattern is due to the combination of the Fraunhofer diffraction of the circular aperture, the the blades of the iris at the f-stop, f, and the slits of the Bathinov pattern. The ...

The number of line pairs across the diameter of the Basinov mask needs to match the intended aperture to be tested.  A 50 mm lens at f/1.8 has an effective aperture diameter of 28mm. This is the ...

30 minutes after I wanted a Bathinov mask I had one in a 52 mm threaded mount.  The same evening I was able to try it out. I have not tried it, but I should.

It is not that hard to make one yourself. It took 30 minutes. after finding the instructions http://www.deepskywatch.com/Articles/make-bahtinov-mask.html . Print the 62 mm pattern on paper and ...

Very nice. At f/2?  From a dark site? It will be interesting to see how the galaxies pop out, once the  you get the lens in focus, At f/2 there is no room for error. Does the lens improve at f/2.8? hha

Nikon 28mm f2.8E. I have used it on my D7200 and my Z6,

I am not sure what you are telling me, since I am not a  collector. For taking star picture this 1957 Topcor 135mm/f3.5 at f/4 is better than my Nikkor 135mm f/3.5 Q at f5.6 from 1975. But my ...

Do you have samples at f/2.5? You left out the photon noise. You increase the signal (2.5/2)^2=1.6, but the noise increases at the square root, so the net gain is only 25%., All of you suggestion ...

Photos further down,

I included photos further down. Apparently this lens was made to fit on the Leica knockoffs produced win Japan.

Thanks. This was a very helpful reference, which show the lens. It was apparently made for a the Leica copies. It appears to be 1956 vintage. Optically (for star pictures) it is much better than ...

mapachebasura If the Nikon Z6 does not allow you to put your lens close enough, nothing will. Get a cheap Leica screw mount to Z6 adapter (Fotasy US $18) , bore out the Leica part and insert you lens.

ffereres: I have taken many star pictures with a Nikkor 10P mmP f/2.5 at f/4, Excellent lens, but i  wanted more star-like patters, not round stars. I have a Nikkor 135 mm f/3.5 Q, but the blue ...

Interesting. Thanks for all the history lessons. Here are two pictures The picture makes it look like the lens has a barrel bulge in the middle. Not true. I got too close Here it is from the front. ...

Thanks for the information. I checked the mount. It is not a detachable adapter from one mount to another but attached with 3 screws to a brass ring which ends in the Leica screw mount.

Sorry, typo. Topcor.

I found this Topor 135mm f/3.5 (chrome barrel) with a Leica screw mount in my collection of old Leica gear. My guess is that the Lens is from the 1970s, At that time TOPOR was a top brand. So I ...

All the previous responses are good. The best one is to start with a photographic lens and a simple sky tracker. Here is what you can get from a Nikon Z6 with a 40 year old Nikkor 105mmP f/2.5 at ...

At iso200 you may get a little digitization noise, at least that is what I get with my D7200 and Z6, so I stay at iso400. I find the Bortle scale not very useful in estimating how much you may gain ...

Very nice result from a backyard.  What iso did you use? Your 130mm f=650 mm system is f/5. How big was the sky background  (histogram level))? From this and f/5 you can estimate how much a good ...