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I'm struggling to find any clip in filters for my nikon d5100. Light polution filter required really but interested in any recommendations from your good selves for Milky Way or DSO imaging.
Do any of you know where I could get any, second hand or otherwise?
A few months back, i bought my first mono camera, an Atik 383l+ from Martin @Xsubmariner off here. I hadn't had a chance to give it a whirl until last night.
I thought about getting the 80ED out, but i've been wanting to do some widefield stuff for a while, so i attached an old Tamron 135mm F2.8 vintage M42 lens i picked up last year for next to nothing. The lens needs to be stopped down to F5.6 (perhaps less, i haven't tested though) to produce acceptable stars in broadband, but i was hoping it could be used more wide open for Narrowband. I used step-down rings screwed on to the end of the lens hood to bring the aperture down to 37mm, which is about F3.65 (i did briefly try it wide open in Ha, and it wasn't that bad tbh, but i could still make out some comet-shaped stars in a few places so i opted to stop it down a bit to play it safe). I have a TS Optics filter drawer in the optical train, so i can still swap out filters without too much fuss. I still have about 3-4mm of extra backfocus space to spare, but i can already find focus as it is, so i'm not sure if it's that important that i haven't fully used it all up.
Focusing was tough. I was focusing using a Bahtinov mask on Deneb, and i had to use 10s subs (subframes) at 2x2 bin to get bright enough spikes for Bahtinov Grabber to pick up to the spikes ok. Even then, it was showing the focus error moving about quite a bit, even without me touching the focus ring. In the end i just got it as close as i could and went with it.
Conditions were not great. Some clear spells, but there was a lot of cloud passing through. I figures it would be good enough for a test session. The Phd guide graph looked horrific, and was somewhere in the 1-2" range (image scale is 8.4" so not a big deal hopefully). I bodged together a couple of old dovetails to add enough weight to counter-balance the 5Kg counterweight. It just about does. It's not perfect by any means, but hopefully sufficient for this purpose.
I would ideally like to shoot 1200s subs, but couldn't last night due to the constant clouds (Phd lost the guide star countless times). I was about to give up, but persisted and aimed for 600s subs. Glad i did, as i ended up with 6 useable subs, even if a couple were affected by some thin cloud.
Did a quick stack in APP and a 10 min process in PS, just to get a rough idea of what i can expect from this. I used Flats and a couple of Darks just to do a rough calibration. Didn't do any gradient reduction, was in too much of a hurry after packing up last night. Overall i'm fairly pleased with how it performed. I'm obviously not aiming for Samyang 135mm F2 levels of performance here, but for purely NB bi-colour mosaics i think it can do a job.
I've included a picture of the rig below as well, in case anyone's interested.
6 x 600s (1 Hr)
Atik 383l+ 2" Baader Ha 7nm
Tamron Adaptall2 135mm F2.8 (@F3.65)
as well today the sun is shining brightly here. I set up the Lunt to have a look at it, at first just for observing. However, somehow I cannot resist and have to do a sketch This time I've chosen reddish pastels on grey paper to better catch the color of the view in the eyepiece.
Telescope: Lunt LS50THaB600PT
Eyepiece: Celestron X-cel 10mm
Date & Time: May 15th, 2020 / 1400-1430 CEST
Location: home terrace, Dusseldorf region, Germany
Technique: red and orange Koh-i-Noor pastels and pastel pens on grey Canson Mi-Teintes pastel paper
Size: 24 x 32 cm
Clear (and sunny) skies!
I finished observations of the Mizar A spectroscopic binary.
Calibration for the Hα line made on water lines contained in the Earth's atmosphere.
I used LowSpec spectrograph with 1800 grooves/mm reflective holographic grating, APM APO 107/700, QHY163M camera and HEQ5 mount with guiding.
It turned out that the Earth's movement practically compensated for the radial velocity of the Mizar A system.
Based on the analysis, I received the result:
vr = -8.8 km/s
in fact the system is approaching at a radial velocity of -6.3 km/s.
I also determined the phase plot of radial velocities based on my measurements for the Na (together for both lines) and separately for Hα line:
Error is based on half my spectral resolution (0.2 Å/pix corresponds to rv = 10 km/s). Each measurement corresponds to the stack a few images.
The most important purpose of observing this binary system was to record the historical Ca II line (often called as CaK, 3933.66 Å).
The distances in the violet part of the spectrum are almost 2x smaller than the corresponding shifts for the Hα line. This line initiated the discovery of spectroscopically binary systems, and Mizar A was the first discovered system of this type.
These were the spectroscopic observations in the 19th century:
I've made several observations of this line in the last two weeks:
Animation showing the changes in the CaK line based on my observations:
Not only the Ca II is split, but the surrounding lines also, shown below in a wider environment:
Balmer hydrogen lines are becoming more dense as Balmer's gap approaches (3646 Å).
Observation result of the Hα line:
And animation showing the changes in this line:
The Na I doublet was much more difficult to observe, because stars with A spectral type contain very faint lines of this metal:
Animation showing the changes in the sodium doublet:
We received the sodium quartet