StuartT

Brill! Thanks for this Kev. Very reassuring. Only had thick cloud so far of course! 🤣

That looks exactly the same as mine (I suspect they are all made by the same manufacturer). If so, you can set any interval you like. It's just that it measures the interval from the start of the exposure, not the end of it. This means you add the exposure time to the interval you want. Example. You want to take a total of 40 exposures of 30 sec each, with 5 sec between them. So enter your LONG as 30s then enter your INTVL as 35sec then enter your N as 40.

I just bought a pair of these and I wondered if any of you had experience of them? I've not had a clear night yet, but I tried them on a distant skyline object during the day and was a little alarmed at the degree of chromatic aberration. Are they uncorrected perhaps? I guess that might explain why they weren't very expensive (£100)

Thanks. This is encouraging as I have a Tokina wide angle on order. So fingers crossed! the video is remarkable! Who’d have thought it was that easy. Just tried it on my 18-55 though and it didn’t just pop out like his did. I didn’t like to pull too hard and risk breaking my lens!

thanks. Although I see that he didn't actually report back, so maybe he didn't 'cut a bit off' I must admit I can't imagine how that would even be possible! Some non-Canon lenses may not have that protrusion, I guess?

I did buy it new, yes. Although now I look at the website again, it does say at the bottom that it is not for EF-S mounts. I really need to read things properly!! So I very much doubt they would refund it. However, I would still be able to use it on the telescope with a T-adapter, so all is not lost. It just means I can't use it for wide sky photos, trails etc.

whaaaaat??? oh no! 😥

I just got a Skywatcher CLS filter for my Canon. But when it's fitted, the lens won't go on (as there is now insufficient space for the lens to protrude inside the camera)! I thought these things were supposed to be able to work with lenses? At least according to this video

Right. I understand now. I was thinking of field rotation between exposures, but missing the important effect of field rotation within each exposure. I can see why that would be a problem. Thanks!

Thanks both. In fact, I was just using Stellarium to identify fun things to look at, then getting it to move the telescope to roughly the right place, then manually fine tuning position w the hand controller. I guess I was just wondering if there was some way to tell Stellarium what fine adjustments I'd made (and hence 'correct' it's understanding of the scope's true position)

Thanks for this. I'll check that thread out

Hi. You're sure more expert than me! Yes, I am aware of the dual problems of long focal length and AltAz mount. I guess I just wanted to see what might be possible, even within those limits. Hence why I restricted myself to 30s exposures. So far I have been mostly looking at the sun and the moon (where those issues aren't really a problem). But if I decide I really want DSOs I shall buy some new toys. Question though - since Deep Sky Stacker is able to deal with translation (during registration) why would field rotation be a problem for it? Can't it also rotate images as necessary? ooh! Definitely an improvement! Thanks so much for taking the time to do this 😊

Ok it gave me two options to save the 32 bit FITS file (integer and rational). So I exported both integer.FTS rational.FTS Thanks again

Thanks. I wasn't sure how many frames to shoot, so this is helpful. I realise a f/10 isn't great for deep sky, but it's what I have 😉 Afraid I don't have the LX90 on a wedge, just the regular old altaz fork. No guiding (I'm not clever enough). That's why I stuck to relatively short exposures. Umm.. I'll have to look all that stuff up! 🤣 Yes, the image is heavily cropped. By oversampling, do you mean I am shooting at too high a resolution? I guess with my current setup, I can't really go any longer that 30 sec exposures. What do you want me to post? The light frames? Or the text files that DSS generates?

yes, that's correct. It's a bit silly to design it that way, but it's fine once you get used to it. Oddly enough, the intervalometer in Canon EOS Utility works the same way! 😕

no. You've misunderstood.

I think you misunderstood. I didn't mention anything about 5 minute exposures. I was explaining that on some intervalometers if you want 5 seconds between exposures you enter it as 1m5s (rather than 5s). I'm saying the same as fwm891 You can do exactly the same job with it, the only difference is how you enter the value of the interval. It's pretty straightforward.

Last night I tried my first serious attempt at creating an image of a DSO (as it was very good seeing). I selected M51 and using a Canon EOS750D at the prime focus of my SCT I shot; 46 lights, RAW, 30 sec at ISO6400 16 darks, RAW, 30 sec at ISO6400 16 bias, RAW, RAW, 1/4000 sec at ISO6400 Then I combined them in Deep Sky Stacker. It was set to a threshold which found between 100 and 250 stars and the stacking was with Kappa-Sigma clipping. This is the result after stretching. A little underwhelming. Any tips? (I didn't shoot flats as I can't figure out how to do that without an iPad!)

On my intervalometer (Viltrox MC-C1) the interval timer starts from the beginning of the exposure, not the end of it. So your interval needs to be a few seconds longer than the exposure time (to allow the image to be written to the card). If you are shooting RAW the files are bigger and so take a little longer to be written. So if your exposure time is 1 minute, you should set your interval to, say, 1m 5s. Or maybe to be super safe, 1m 10s

great. Thanks so much both of you. Personal recommendations are worth their weight in gold.

ok, I think tonight's is better. 250 x 5 second exposures at 7 sec intervals combined using Startrails. 17mm lens, f/3.5 ISO 3200

I've got Stellarium steering my telescope, but it's a little out. I'm currently taking subs of M51, but I had to manually adjust the scope a little from where Stellarium put it. (you can see from the capture that it's a little to the east of where it thinks it is) 1. is there a way to tell Stellarium to make a little adjustment to its alignment? 2. can I adjust the scope slew from within Stellarium? (as it's a bit tedious going out and tweaking the hand controller, taking a photo to see where it is, going out to tweak again etc etc etc)

ooh.. might have to buy myself one of those. I haven't bought any gear for days! 🤣

I have a problem with the autofocus on my Canon EF-S 17-55mm f/2.8 IS USM Any suggestions as to a good UK repairer? Thanks

no, I do mean 16 minutes. Otherwise, there would not be much trailing. Even 16 min is only 4 degrees of rotation. The reason I don't have more stars is that I was at f/11 anf ISO100. (I live in town 😥