teoria_del_big_bang

I only seem to have screws as small as M2.5 that I can find at the moment (I am sure there are about somewhere, if I ever find I would send some with pleasure) but I would be tempted to try a M2 screw, maybe as Neil says off ebay (might have to get 5 of them but should be cheap. Go for stainless, I would think that at this size they will all be full threaded even if not stated as such. Steve

That actually look like it could be metric, I would guess M2 x 10 mm. If you look at the diameter of the threads it looks to be bang on 2mm. I blew one pic up in paint and turned the thread round 90 degrees against the ruler. The pitch best I can see if I blow the photo up is 0.4 mm which is M2. These are readily available and I probably have some if you want me to post one to try. That just leaves the spring (if it is an m2)

Yes I suspect as Alan it will be imperial so either UNC (Unified National coarse) or if a fine thread may be UNF (Unified National fine). If you can find the diameter of the threads accurately as there are a number of screws this size with very little difference in diameter that narrows it down tremendously. If UNC or UNF then dimensions are in inch but if you can give in mm then we can convert. You will ideally need a pair of calipers or micrometers. Then knowing the diameter we need the tpi or threads per inch, or in 25.4 mm. My immediate suspicion is it is either UNC #4-40 (40 threads per inch) or UNF #4-48(48 threads per inch) but that is just going on the 2.5 to 3 mm diameter suggested by Alan. Steve

I have just bought a set of Baader 36 mm unmounted filters (LRGBC & NB). I have also found the following information on the Baader website. Always put the more reflective side towards the telescope side. On these filters were the position matters. This arrow indicates which face of the filter should be directed towards the sky (telescope-sided). All cell-mounted filters are already oriented in a way that the most appropriate filter face is facing the sky when the filter would be mounted directly on the front end of the nosepiece of a camera. If you mount your filter the other way, any reflected light would have a short to the camera sensor, resulting in a higher risk of getting some kind of back-reflections inside the camera field. Many sensors have highly reflective areas near the light sensitive area. But: this is true only for instruments without optical elements near the focal plane. If you have a coma corrector, field flattener, focal reducer, focal extender (to a lower degree due to concave surface), or in extreme cases a whole lens group for more complex field corrections a few centimeters in front of the filter it could be useful to flip the filter against the rule from above (thus having the arrow pointing away from the telescope). Cause in such cases the likelihood of reflections from the sensor could be better then fort and reflections from such glass-surfaces. If in doubt, it helps to make some test images from a star field with bright stars, using the filter in both ways for comparison. I do have a flattener but just thought I would check whether others have found the above to be true or not. Also I bought the full set of LRGBC filters my reasoning being that as I have a light pollution filter in the flattener which is applied which ever filter is selected I thought for Luminance I would be better using the clear filter. I can only fit 7 filters so need to either fit the clear or L filter, so am I right to use the clear one, or does it not really ,matter? Steve

Really nice clear images 🙂 Steve

That is pretty amazing. Your dedication (or madness) is to be commended 👏 Steve

I think it was well worth it. Sent mine to this place. Had it back in the week and not expensive. https://www.cheapastrophotography.com/ Steve

Thanks for sharing that with us. Brilliant write up 🙂 That must be about the most modern looking observatory I have seen. Steve

Thanks Magnus for sharing your holiday with us 🙂 , great write up. Just remind me again what that blue stuff behind the clouds is ? Steve

Very interesting. Probably was the Speakeasy as that was a very popular haunt for these bands. The time is spot on as they would have been then New Yardbirds then and late 1968 they would have had their first tour. Being sacked for trying to sign Bowie and King Crimson 😱, big mistake on Mercury's behalf eh what. Steve

Now there's a name I have not heard of for quite a few years 🙂 Was it a good concert? Looks a nice camera you plan to get. Steve

What filters are they (make and bandwidth), are you talking the usual Ha, OIII & SII? I am not sure all makes are the same but my Baader and some unbranded ones the OIII looks Green when you look through it at a light source Ha and SII both are Reddish / Magenta but would say the Ha is more towards the red and the SII more towards Magenta but that is very unscientific and not very helpful. As they are unmounted are the edges at all different colours that you can match to pictures on FLO or similar as Michael suggests? Steve

I have taken this week off work originally with the idea of going to lakes for a couple of nights, maybe taking some of my gear, but we did not book anything and so with the weather as it is decided just to stay at home. Plan B was to stay at home do some building work in garden with a bit of stargazing at night with the knowledge I did not have to get up in morning. But it is not going to be plan B either. Plan C might be the pub 🙂 So I have sympathy and hope where ever you have gone it does brighten up as some stage. Steve

I must admit I thought it was when I first looked but then so many in France are of a similar design so was not certain. Oh I am so jelous now. The photo alone was amazing and now knowing where it is it must have been a wonderful holiday 🙂 Steve

I decided to go for the Baader Ultra NB filters and managed to get Ha and OIII from Ian King but cant seem to get a SII for love nor money at present so will have to wait for that one. I have gone for the 36 mm and ordered the LRGB set from FLO. So hopefully may have a full set before the longer clearer nights come (if they come). 🙂 Thanks to all for the advice and help. Steve

I think I am settled on getting 36 mm filters. For the same reasons as you have mentioned. Also the mention of the Baader Ultra NB filters mad me think again. They are a fair bit more expensive than the original Baaders, still cheaper than the astrodons but may be a good compromise, especially as you are not the first to mention the halo issue. So my issues are solved eh, not quite. Next issue is getting hold of some. They seem to be pretty short on supply at the moment, especially in anythng other than 1.25". FLO had an estimate of 40 to 60 days delivery but an email to them has revealed they really cannot give an eta at all (or rather Baader cannot). God if somebody had told me a few years ago before I got into this that I would be willing to pay well in exsess of £200 for a bit of coloured glass not much bigger than a coin I think I would have choked. But these bits of glass can make all the difference. Steve

I too told him I had bought 2nd hand as well and asked for a quote to give it a service so I may still get a bill which I am more than happy to pay of course. But yes absolutely brilliant service, which is not seen that often these days 🙂 Steve

Thanks for the advice. I eventually got round to doing it and Terry got right back to me and believes it could be due to my wheel beng a very early version that does not like 64 bit windows and has offered to reprogram it if I send the unit back. Such great service, this is a second hand unit, well old. Steve

will see if I can find it again and let you know. It was easily solved by sealing the edges with either tape or carefully applying paint (only to edges mind obviously). This may be unfounded or I may have misread something as I was not really considering unmounted at the time so did not look too closely. Steve

@upahill Thanks for the reply, I just had to laugh when I saw caffeine in your equipment but agree how important this is on a night. I assume as it is listed after the Baader items it must be filter coffee you are using 🤣 Steve

I agree 1.25" or 31mm would be fine for my current setup it. The cost difference does not worry me too much as it is not massive (about £475 for 1.25", £615 for 36 mm unmounted, £700 for 2") so to future proof them I would pay the extra. But yes you do make a good point about whether I will ever get a bigger sensor and as I am shortly to retire to splash out probably £2000+ in the future does seem unlikely. I guess especially for NB the Astrodons must be worth it as they are so much more expensive people would only do so if that were true. I guess for now I would have to either forget NB for a year or so or use my current astronomik ones and save or just decide my pockets are not that deep and to get the Baader ones. I have read also that the unmounted ones can cause issues with reflections if not sealed around the edges - any thoughts on this. Steve

Thanks for that, I had sort of come to the decision to go with Baader. My next issue is whether to go the 36 mm unmounted or 2" mounted. I know with this ccd I should be okay with 1 1/4" but to ensure vignetting is definitely kept to a minimum wanted to go a bit bigger. 36 mm would be fine and more over lets me use a 7 position wheel so that I can have all filters permanently mounted. 2" maybe overkill but means I have some decent filters that would last me and would cater for any future needs(I doubt I will ever justify the cost of Astrodons), but that means using a 5 position wheel and changing between LRGB and NB but this is a minor thing and not really an issue just need to decide if I would be better off with 2" or whether 36mm would suffice. Steve

Okay so another novice question. If I have a LP filter permanently in the imaging train, specifically the IDAS P2, when taking luminance does it matter if I use a proper luminance filter or just the clear filter. A clear filter would then just rely on the LP filter to block IR but keep everything more in focus and retain the back focus from the flattener. Would using the L filter as well as the LP filter block more light or not? Steve

Its the WO Flat73 (not the newer 73A with adjustable spacing). I have actually just found this thread started by @fwm891 which shows the filter on the front end of my flattener. So that answers one of my questions. However, do I leave this filter in if using NB fiters. I am guessing although not required it will not have a massive effect either way.

Hi John, I too am very new to the ASI1600. My LRGB filters are as close to sensor as possible, but they are not ZWO filters and the couple of times I have had chance to use them this summer I have had some vignetting using 1.25" filters (Astronomik I think they are) so wondered if the ZWO ones would be better, or maybe go to 36 mm or 2" filters but this could get expensive with NB as well. But I have read that some people also add a LP filter in addition to the LRGB which obviously then has to go elsewhere than the filter wheel. So my thoughts are at present is to fit it in front of the flattener to avoid affecting the back focus of the flattener. Steve