tooth_dr

Hi David. Thanks for tip. I was in the process of doing just this, rigidly attaching a finderscope to the longer scope. I can leave the oag in situ, and try out the finderscope guiding. Clear skies will be the only hurdle 🤷‍♂️

Thanks guys I’ll get back to you all later when the kids are in bed, it’s the middle ones 6th birthday today. Its a new ZWO OAG from FLO.

I was wondering if I can get some advice/opinions on this. I have just started using a mesu 200 mk2, and initially started with a 500mm newt/finderscope guider and a 120MM. I was getting around 0.4"DEC+RA -> 0.6"RMS total (peak to peak 1.0"RMS). This was 3-4 times better than the 2.23"/px imaging resolution. I set up a 1200mm scope, which is similar in weight to the 500mm scope, in fact uses less weight to balance, but is obviously physically bigger. I'm using a ZWO OAG with this, and a 178MC (binned 2x2). I can barely achieve 1.0"RMS, with larger deviations, giving a peak to peak of 2.5"+RMS (on two separate nights, the second of which - last night - the stars are not round in 3min subs, however in the first night there were round). The scope/camera has an imaging resolution of 0.93"/px. Obviously this isn't an acceptable level of accuracy for the scope/camera combo. So I've never used an OAG before, and I appreciate that it is going to minimise differential flexure, but I'm disappointed in the performance. Where am I going wrong? Could it simply be poor seeing, or is there something else I'm doing wrong? I think all the parameters are correct in PHD2. Does it automatically adjust the graph scale for binned captures, as I'm using 2x2 to get better sensitivity, bringing the pixel size to a still ok 4.8px. Any pointers welcome. Here is a sample sub from last night. I can attach PHD guidelogs from finderscope and OAG if this helps? I focused with a bhatinov mask, and it looked, but as you can see the quality of the sub is poor. I didnt touch anything on the scope (except electronically focused) between the two subs. I've never really paid attention to seeing, because I'm only ever imaging at a short FL, and even bad seeing wouldnt have much effect. Is this just the norm when trying to image at a higher resolution? I would have been better try to get RGB last night, but I guess this is a lack of experience shining through. Best wishes Adam. 180s luminance sub 30/03/20 600s h-alpha sub 29/03/20

Great detail in the dust lane, top work Mick

You can using the wheel to adjust the exposure stops. You don’t have this set to -5? @Johns22

Ive never had any issues with AV mode with telescope attached.

I also used AV mode for flats. It’s works 100%. You could use the +/- dial to fine tune if you wish. But I 1/2000 is too short. Try a few more layers of T-shirt to get it down to 1/50 or there abouts.

Tim Have a look at this thread, might help..

You are allowing all the light to get through using an UV-IR blocking filter, so it will allow Ha Sii and Oiii through, but also every other wavelength from 400-700nm. Ha is not in the IR, it's 656.3nm, which falls within visible light and within the UVIR filter 400-700nm. If you want to take broadband colour images of objects, then get a UVIR filter (or Light Pollution filter depending on your local environment ). I havent used that filter, but it appears to be a strong LP filter. Anyway it will work, but you will lose some data as it will be blocked by the filter. Does that help you any?

Very nice, plenty of detail 👍🏼 Im not sure I’m come across any images of NGC7023 using Ha, can you share a link to some as i would be keen to see them

Hi Nice write up! Can you post the image as well as the video? Thanks! Adam.

I wasn’t suggesting that particular filter, just an example for the type of filtration that would be useful. UV-IR. What scope is it for? Do you want to use it with lenses? How is the DSLR attached to the scope?

I agree. This is one of the best renditions of Pacman I’ve ever seen. Fantastic.

I was thinking of guiding on the comet when it’s clear again and trying to get a decent image. I’ve guided on a comet before but the resulting image wasn’t great. Is it pointless?

I ordered an Atik adapter for my EFW3 yesterday and it sitting at the door when I returned from work today 😎 Thanks!

Very nice. How did you process it?

A simple UV-IR filter - https://www.firstlightoptics.com/uv-ir-filters/astronomik-ir-blocking-filter.html

Hi Gary The 178 has very small pixels, I have one of these myself, non cooled version. It has 2.4um pixels. So at 1000mm focal length on the 200PDS, you will have an image scale of 0.49/px which is very oversampled. It would also present a tiny FOV, but for galaxies, maybe? You'd still need to bin it to get a decent image scale, so at 3x3, you'd be imaging at 1.5"/px, and have a 1032 x 693 resolution.

300s James

I’ll try that now. Thanks.

Thanks Sean. This is a crop to reduce the video size. I am using an Atik 383L+, which is a mono camera with 5.4um pixels. It gives an image scale of 2.23”/px which is ok. I tried stacking on the comet but DSS wouldn’t acknowledge the nucleus so it couldn’t be done.

Looks good Ciaran, nice to see you imaging again. Lots of colour and detail, the OSC is a success! The background has suffered a little from the lack of dithering, but this is only a minor comment! Keep them coming please. Adam

Thanks Graham. In the animation there are 5 frames of red, then 5 green and finally five blue. Green, as you’d expect, is the brightest.

Here is my WIP of the Rosette, data collected on the 12th, 15th and 18th March 2020. Ha 9600s Oiii 7800s Sii 4800s Takahashi Epsilson 180, Atik 383L+, Optolong NB filters, EFW3, 600s subs at -20oC, total integration time 6 hours 10 minutes Thanks for looking. Adam

That’s really excellent. Hurts my neck looking at it though 😎