hha

Your D5600a has the extended red response. This probably explains why M57 with your D5600a has a little reddish cast compared to the more blue with my stock D7200. Cheers, hha

Hi: Mario. Thanks for the screenshot. I rotated and scaled it to approximately match my image. Yes. M57 is resolved with your Sigma 105mm at f/2. Very impressive. cropped from 4000x6000 D7200, ...

Mario: Nice lens and lots of stars. Two days ago I took images of the Lyrae constellation with a 135mm lens, but I posted only a small crop (at full resolution with a D7200) of the Vega and ...

When stopped down a little, all lenses show a diffraction pattern (sun star) around bright stars. For some lenses the pattern is ugly, for other it can have an artistically pleasing effect. Shown ...

Thanks for the picture. It appears to cover a 3 degree area. To analyze your "No CA" comment I did some manipulations in PS. On the left is a picture of eps10/20 Lyrae cropped from your picture ...

Maybe a 200 or 300 mm lens would be a good starter for clusters and some of the bigger galaxies.  The longer and bigger lenses on your list require a lot of experience and $$$. hha

David: Interesting writeup. I have accidentally taken and processed series of defocused images. All but the faintest stars  tend to have magenta or cyan haloes, depending on  which side the focus ...

Yes, this 50 year old lens Nikkor 200mm Q f/4 lens, used at f/4. It has only four elements, and was corrected for only two colors, i.e. achromat. The challenge I proposed to the readers is to take ...

Tristimulus: Notice I said "colorful stars" not "star colors". Since we are not doing any science with these pictures, a little color thrown in, even if an artifact of the lens, does not hurt. You ...

I got tired of looking at colorful pictures of emission nebulae, so here is a colorful star pictyre. On the left is a  300x600 crop centered on  eps01/eps02 Lyrae, taken with a 50 year old Nikkor ...

The Earth rotates 360 degree in 24 hours = 15 degree/hour = 15 arcsec/sec.

Obviously, if your polar alignment is not perfect, you will get trails. How long a trail will you accept in your 1 minute exposure? How are you going to process the data afterwards? Here is my ...

Very nice result  of M13. What caused you to limit the exposure to 120 sec per shot? hha

For a 24 Mp camera the rule of 500 is way to slow. The first picture, which shows the moon emerging from the hillside at about 12 degree elevation, was taken from a fixed tripod with the 200mm ...

For those who got clouded out Nikkor 200mmQ f5.6 iso200 10 sec StarTracker. Enjoy. hha

I am routinely getting 4 hours (240 shots at 1 minute each) from a 2280 mAhr ENEL 15C battery with my Z6 and be down to one bar on the battery meter,  You can scale it from there. A 5000 mAhr 7V ...

This time I centered on NGC4649 and missed the Markarian chain. I did a quick slice across the the SN and NGC4649. The SN as of 4/30/2022 22:00 PDST  is 2.5 times brighter than the nucleus! Cheers hha

Andresch: A 400 mm should work, obviously not as good as your 6"/f5. (f=750mm).  On Saturday night  I took 4 hours (240x1minute) of images of the Virgo Cluster with my Nikkor 180mm ED f2.8 at f/4 , ...

Very impressive picture. I tried from my backyard (Bortke 7) with a 180mm f/2.8 ED, but the sky was too hazy. In the 1990's there was a group at  the UC Berkley Astronomy department, which hunted ...

Excellent for a first attempt, with darks, lights and flats in 50 x 4 = 200 seconds. A Bortle 2 sky helps. You used a Sony 85mm f/1.8 lens. In 4 seconds you will get 60" of sky rotation. Barely ...