parallaxerr

Clear as a bell but gusty here. 80 subs on M31 in the bag, this time at ISO 3200. Having learnt a little more about reading histograms etc, looks like the blue channel is being clipped at any lower ISO on the fuzzies, probably due to the semi-apo filter. Found out I do still have a slight alt limit in that the intervalometer plug connected to my Nikon contacts the mount, it bends out of the way but does offer some resistance so I've now re-targeted. 90° plug on order & M33 subs underway.

Loving No.4 Ken

Like the sound of that Ken, especially the user defined areas. More functions than I realised. Dear Santa......

How does the starsense cope with an alt limitation? Despite getting good alignments, I've been fancying one for the plate solving, but I thought I may get a mount conflict if it's free to slew where it wants.

Made a few changes to my set up last night as a result of the discussion above. The WO OTA has an L bracket attached which has a vixen dovetail form. It's neat but doesn't allow me much adjustment. I dug out a 7" dovetail and eventually found some bolts to fit as the two required are different threads!!! One bolt goes through the dovetail and attaches to the L bracket photo tripod adapter which is 1/4-20UNC and the other goes through the dovetail and L bracket and screws into the OTA, think its a UNF thread. I had to remove the plastic trim around the dovetail clamp as the focus knobs inerfered, but now I have full freedom to slide the scope fore and aft. The result is that I'm now balanced slightly objective heavy. Hopefully this means the Alt gear is always under load and driving the scope up instead of allowing it up, as it was when tail heavy, if you see what I mean? Also, I now have no Alt restriction The clutch was also a tad loose. Whilst there was some friction between the plates, there was barely any torque on the nut so that's been tweaked up. Hopefully less binned subs next session.

I found this made my goto accuracy worse. For some reason, after syncing to a nearby star, the goto to the target object was not repeatable, neither was returning to the sync object? Auto two star works best for me, then straight to target, take one sub, adjust framing then start collecting. I reported a judder in the alt axis to FLO just recently. Martin was quite explicit about using 13+ volts for a supply. Ensuring I have at least 12V reduces the effect but it still happens occasionally, so these mounts are obviously voltage sensitive. I guess you have little option with the Evo internal battery though. Can you use external power too? Good shout Nige, I did the very same about month ago after a re-grease to the main gear. Last night was by far the coldest I've imaged in so maybe a little contraction in the clutch let things slip. I just grabbed the OTA and it moved in Alt, not easily but readily so you may be on to something. My star trails were straight up, which agrees with this theory - where's that spanner...

Interesting because my setup is already very tail heavy. So much so, I was thinking of getting an ADM dovetail bar to move it forward a little.

Fortunately the wetness was dew not rain, so no harm done. Here's the result of last nights attempt, second go at M42. This time I gathered more subs, although only an extra 30mins or so despite being out for an extra 2hrs. I had some serious PE (I think - major star trailing on Alt axis for 4-5 frames each time) every 10mins or so, so lots of subs got binned. Also had about 15-20° field rotation at a guess, so lots of cropping was required. WO ZS66SD unguided on Nexstar SE 6/8 Alt/Az, Nikon D3200 w/Baader Semi-Apo filter. 198x30s subs, 50 dark, 50 flat, 50 dark flat.

Well that was dumb! Put the scope out a few hours ago to cool, not that a 66mm frac needs much cooling time. Did my alignment, hibernated the mount and turned everything off, including dew heat, awaiting the rise of M42. Went back out to get started and everything's dripping wet, no drama. BUT, took the dew cap off and the objective was totally fogged over. Had to put an extra dew band on along with the normal one and put my hand warmer in the dew shield with cap back on for 20mins or so to clear the objective, not sure if that will cause imaging issues?

Well the weather didn't exactly play ball tonight but I got my experiment done and I'm really happy with the result. Had a window of about 1.5hrs to image and grabbed 59m30s of decent subs. M42. WO ZS66SD, Baader MPCC & semi-apo filter and ISO800. 119 x30s subs, 50 dark, 50 flat, 50 dark flat. Bashed this though startools as fast as I could - Autodev, wipe, autodev, crop, bin 50%, colour, de-noise. That's it, left most settings as standard then upped the brightness and contrast a touch in GIMP. There's a slight green to the stars, probably from the filter buy boy do I prefer an apo, bye bye CA! It's obvious I need more subs with the smaller scope but that's fine, I'll keep adding to them now. Much better FOV too, think my mind's made up on which scope I'll be sticking to imaging with and keeping the ST120 for DSO visual (if I ever look through it again!). Only downside is a touch of coma top corners which the ST120 didn't suffer with, maybe there's a little tilt in the WO focuser? P.S. Calibrated my monitor today, hopefully I'm now seeing the same images as you guys, the gamma was waaaaay off!

Thanks Neil, looks good. Guys, whad'ya think. I should be using the ZS66 not the ST120 right? If I've got a doublet apo on hand why not use it. The ST120 probably grabs more photons in one go but surely not having CA in the first place is preferable. Am I going to lose out with the smaller scope? The pixel resolution comes in at 2.04" with my camera so I'm unlikely to see any square stars but is 66mm "enough"?

Yes, the running man fell foul to field rotation unfortunately, so had to be cropped out. The ZS66 should capture it and now I'm starting to get some idea of what I'm doing I may experiment with rotating the camera!

This explains the Baader series best Ian... http://www.baader-planetarium.uk.com/en/pdf/baader_contrast_filters_US_ATT_review_0414.pdf

Reprocessed with flats & dark flats which have got rid of the amp glow or gradient or whatever it was and left the colours a little more "natural". I stretched this image further and applied less noise reduction but the background has still come out pretty dark just using as simple ST workflow. The final conversion to TIFF then JPEG appears to adjust contrast slightly too. I really don't like the CA. I tried the fringe killer filter but didn't get on with it. My next attempt (hopefully tomorrow night) will be with the ZS66 AND the semi-apo filter to cut back moon & sky-glow. I'll see how the histograms look through the different setup but hope to try ISO800.

I was using less leg extension with the ZS66 but wanted the ST120 a bit higher, there's still a good bit to go, I never go full extension. Doesn't seem to have made any difference though to be honest, the most vibration prone part of the whole SE setup is the single fork arm.

Not at all Nige, you've highlighted the gradient I was masking with contrast which obviously took away some fine detail. Just reprocessing with flats & dark flats, gradients gone...

Same here but I don't have the blinky option. I have a feeling I was nowhere near saturating the sensor at ISO400 which is why I didn't capture some of the higher end of the range, i.e. fainter stars.

I think this is where I made a mistake. I set the ISO low to quieten the background but lost detail, at ISO800 I should capture more data and be able to get nice backgrounds through ST. Agreed, although my monitor at home is a 32" LCD TV so I think it needs tweaking. The image looks best here on my work PC, more natural, but looks saturated on my tablet/phone.

I think you're right. There was very little noise in the subs to start with and Startools has tried to reduce it further, so this is a litle too dark. Looks like I'll be trying ISO800 next tiime despite all the theory and specification of my sensor suggesting it's not a good ISO to use, it goes to show that the final image is what counts!

OK, I wasn't going to post this just yet but I have a question - in comparison to other M42's I've seen, there seems to be quite a lot less stars in mine. Probably a result of setting ISO to 400, but I really do like the dark background. What do you think? Stars vs noise? Note: this is far from fully processed. I threw this together at 2am so there's no flats or dark flats, just 101x30s light frames and x50 darks. The image has 4 noise hot spots towards the corners which I think is amp glow, I tamed it by over adjusting contrast and colour. Also it appears my computer monitor colour needs calibrating as this image looks far less vivid on the PC than on my other devices! Also to note, this was taken with the Baader semi-apo filter. It made processing infinitely easier without the sky glow - subs were captured between 20°-30° Alt! After Autodev in ST, the image was washed out a lime green colour instead of red/brown but the wipe tool handled it much better, less noise probably helped. A little disappointed with the CA still.

Yup, I put mine straight into hibernate when the clouds came in. Woke it up again 2hrs later no problem Got over 100 subs on M42, darks in progress now, then it's bed time. Good job I have a half day in work tomorrow!