Lee_P

@symmetalI caught a brief gap in the clouds to test the 57.5mm backfocus. I took three photos as suggested.

0 degrees:

90 degrees:

180 degrees:

Those corner stars are much better than before. I tried a few more pictures after adjusting the flattener tiny amounts in each direction, but to be honest I reckon the shots above are as good as I got. Do you think I should play about some more, or am I being a pixel peeper? It's hard to tell 😅  I've got a light pollution filter, and an L-eXtreme on order, and am dreading putting them in and having to readjust backfocus again!

Following this because I have the same question! FYI my diagonal didn't come with an extra screw either.

Thanks Alan, that's very kind of you of check. Being about 1mm out would fit with your calculation that I should be at 57.5mm rather than 56.8mm. I'm glad to hear that I don't need to mess about with the tilt! I've made the required adjustment on the flattener, just need some clear skies to check. Obviously the forecast is for complete cloud cover for the foreseeable future...

Thanks Alan, you've given me the next steps to try. Now I just need some clear skies..!

Thanks for the reply! It clouded over before I could investigate further. Regarding the calipers, I used them to allow for more precise adjustment of the flattener -- not that it helped..!

I'm not currently using a filter. Is the "2mm protect window" an integral part of the camera? It sounds like 57.5mm is what I should be aiming for. 

One point to note, in my test shots sometimes one corner will seem ok, while others are bad. Could this be an indication of a sensor tilt issue? Or would backspacing explain it?

Thanks again,

-Lee

I've officially reached the hair-tearing stage trying to get round stars to the corners of my frame, so would appreciate some help from the wise folks here!

All my kit is new: WO ZS73, 0.8x flattener / reducer, and ASI2600. The backfocus should be 56.8mm, according to: https://www.firstlightoptics.com/reducersflatteners/william-optics-x08-adjustable-reducer-flattener-for-zs73.html

I've got the image train set up as follows:

* Flattener / reducer set to 1.8mm. I used digital calipers, but it's still hard to know for sure if it's dead on.
* Extender that came with the camera, 16.5mm.
* Extender that came with the camera, 21mm.
* ASI2600 camera -- the sensor is 17.5mm back.

So, that should be the magic 56.8mm.

Here's a test photo. The stars at the top and bottom-left in particular look particularly bad to my eyes.

Here's the original FITS: Backspace.fit

I've tried tweaking the adjustable flattener to modify the distance by tiny increments, but I just can't get all corners to look good. Am I missing something obvious? Any help would be appreciated!

Thanks,

-Lee

Science communication could be an option for you. I did a degree in astronomy but found that sharing my passion with others was more fun than research! I've worked on loads of interesting projects, spent 10 years running the planetarium in Bristol, and now do astronomy writing as a freelancer, mostly for ESA. So it is possible to make a career out of it, although it's a competitive field -- and Covid is really hammering the sector, with science centres slashing budgets and making redundancies

@FLO Do you think the stock issues will mean there's no ZWO 10% off sale this November? (I think there's a sale every year but I could be wrong!)

On 25/09/2020 at 11:07, _Belial said:

Good morning stargazers,

I have a small issue which I'm hoping someone can suggest a solution for with my setup.

I have a HEQ5-Pro and a William Optics Zenithstar 73 II, all good, working fine and finally managed to get some of my first pictures last week and was very please, yey!! However the problem is I cannot get my scope balanced properly on the DEC because I cannot move the telescope far enough forward because the focus rings on the scope hit the body of the HEQ5

Does anyone know of any risers or something that which I can order to lift the scope up and so be able to move it further forward so I can balance it properly at all please?

Thanks in advance

I'm in a similar situation, not being able to balance the ZS73 with a camera attached. The spacers arrived yesterday, which helps with the issue of the focus screw getting in the way, but I'm finding that I still can't move the dovetail very far back because of where the space for the M6 bolts are. Am I missing something obvious..?

1 hour ago, Graham Darke said:

This shot was taken from my caravan in Cumbria where it’s Bortle 3 but I live a Bortle 8/9 Tyne & Wear. Here’s a shot from home with it. The Witch’s Broom. 

That's another great shot, thanks for sharing. Have you ever done imaging with mono +filters, to offer comparisons?

9 minutes ago, Graham Darke said:

Thanks Lee. I’m really impressed with the filter so far. It’s not cheap but for use with a colour camera I think it’s the best out there presently for emission nebulae. 

That's good to know! What's your level of light pollution like? I'm in a city centre and previously used mono + filters which were great, but really I'm after a simpler workflow. I'm hoping that the L-eXtreme could be the answer.

Great picture! I'd be interested to hear your thoughts on the L-eXtreme filter, I'm considering getting one myself.

24 minutes ago, DaveS said:

With the very wide field you will get from camera lenses I wouldn't get too hung up on the "/p figure, afterall you get the same sort of figures from using a DSLR.

That's good, I was beginning to wonder exactly which camera *would* be suitable...

25 minutes ago, DaveS said:

I would be careful about mounting heavy lenses on a camera with no other support, the couplings are designed for putting the camera on a telescope, not the other way round. Pity you're Nikon else This might be an option, though I think you may be able to get a Nikon / Canon adaptor.

Yes, very wise. The only really heavy lens I'd be using is the 70-200 2.8, which has its own foot and tripod attachment, so I guess that would attach to the mount rather than the camera. Assuming there's a simple way to do that. Canon does seem to be much better catered for than Nikon, astro-wise -- and the fact that I'll be mostly using Nikon Z lenses narrows my attachment options further.

Actually, that's a question for anyone in the know: what would I need to attach a Nikon Z lens to a camera like the ASI2600, plus fitting a 2" filter in the image train?

Carole's got me enthused about the lens route! The Samyang 135mm looks great (I spent hours looking through the epic forum thread), but if I could overcome my concerns about using my current lenses -- perhaps not by using particular ones that I might need for a shoot the following day -- then perhaps I could just use my existing collection, inc. 50mm f1.8 and 70-200 f2.8. With that in mind, two questions about lens set-ups, if I may:

* Considering I'd like to use a cooled astrocam, lens, guidescope, red dot finder, ASiair to control it... what's the best way of physically coupling all that kit to my HEQ5? I've seen some 3D printed options (Astro Kraken et al) but they seem bespoke for specific lenses. I'm imagining something something attached to the mount as a base, then this holder to attach camera. Then perhaps the guidescope next to the camera / lens, and the ASisiar at the back. Maybe a tube ring attached to the base plate, going around the lens, allowing for a red dot finder on top... I'm sure minds wiser than mine can suggest something better. Plus I'm not sure how to prevent any kind of sag in the image train if a heavy lens is used...

Edit: maybe something like this? https://www.firstlightoptics.com/dovetails-saddles-clamps/primaluce-lab-side-by-side-240mm-plus-vixen-bar-with-dual-fit-clamps.html

* I don't have a firm grasp on the importance of matching imaging sensor to lens. I was veering toward the ASI 2600, but according to CCD Suitability, that's best for focal lengths around 400mm -- longer than what I'm looking at. So is that camera a no-go with these lenses? Or is it not really critical?

Thanks again to everyone that's helped me so far  

7 hours ago, carastro said:

If you are keen on using lenses but worried about using the workday lens outside at night, why not consider getting a lens for AP. 

I bought myself a Samyang 135mm F2 lens a few months ago after struggling for years to get decent images with a camera lens, and it's every bit as excellent as every-one claims.  Of course it does depend on what camera you put on it and I can't comment on the CMOS cameras as I have only CCD cameras.

Carole 

Yes, that could be an option. Thanks for the suggestion. How do you deal with focussing the lens -- do you have that automated in any way? 

7 hours ago, DaveS said:

If you really want to go OSC and if it must be ZWO for the ASIair then I'd eschew the 294 for the new generation ASI 2600 which has zero amp glow and 16 bit ADC, as well as being a fair bit bigger. I think my preference would be for the QHY version, but of course, it won't work with the ASIair.

I can't answer directly about the various dual and tri band filters as I'm strictly mono, but given your LP, the narrower the better. ZWO do a 54mm filter holder which it might be worth getting, it's available from FLO.

Thanks, that's really useful to know. Regarding the filter holder, they seem to be in-built into the flatteners; is the benefit of the separate filter holder that it allows easy switching? I expect I'd leave the filter in all the time, but maybe it wouldn't pan out that way.

2 hours ago, kens said:

Just to give you food for thought... The most important piece of kit for imaging, especially for DSOs, is the mount. Opinions vary, but I would think that the mount would take up at around half the budget of your kit overall. Looking at your budget , you would appear to be underdone with an EQ5 mount. Many would consider the HEQ5 as a sensible minimum. Most of the frustrations with imaging stem from the mount so if you are after something that is simple and fun you should consider your choice of mount.

Thanks Ken, I realise that I wrote EQ5 whereas I actually have an HEQ5. I'll edit the original post. I bought the mount from SGL's very own Skipper Billy, and it's proved itself to be very reliable and steady as a rock with my previous set-up, which was heavier and had a longer focal-length that what I'm considering next. So it should be a-ok.

Any thoughts from the SGL Hive Mind on my other questions? Would love to hear more opinions! Particularly keen to know informed opinions on the Optolong filters. Thanks!

12 hours ago, Starflyer said:

My first thought would be to put a pier in your garden, attach your mount to it and get polar alignment dialed in. Leave the mount out and just throw a decent cover over it when not in use.

This will cut down on your set up time considerably and allow you to get going quickly. 

Thanks, that's a good idea and is something I'll consider!

Hi SGL folks, I’m hoping to get some thoughts on a future imaging set-up.

I’ve done astro imaging before, with an 80ED, ASI1600 mono plus filters, and an HEQ5. I recently sold most of the kit (but kept the HEQ5), as a new baby has left me precious little free time! I do miss the hobby though, and am contemplating a return – maybe this winter.

I’d be imaging from my garden in the centre of Bristol (i.e. terrible light pollution). My goal is to be able to set everything up with a minimum of fuss (say 20 mins max), and get some decent data to play with over the course of a night. I like nebulae and star clusters – not so fussed about planets. I’d also like any new kit to allow me to produce images as least as good – and hopefully better – than I was taking before. See here for examples. My budget will depend on how well my Covid-impacted work recovers, but I’m aiming for around the £3k mark. I'm not looking to win Astrophotographer of the Year; I want something that's fun and (relatively) simple. I reckon I’ve two big questions that need answering: OTA and camera. (I’ll be using my HEQ5).

OTA
I like short-tube refractors, and I’m leaning towards the William Optics 61 or maybe 73. I find relatively wide angles to be quite forgiving (i.e. easier to take photos with!) and they suit my target preferences.

However, there’s another option… I’m a professional photographer, and so could use my Nikon lenses. In particular, I may be getting the new 70-200 2.8 Z lens in the future. I do balk slightly at the thought of going down the lens rather than ‘scope route though, for a few reasons. I worry that the focal length might be a bit too short; that the lenses aren't made for astro work like telescopes are; automated autofocussing throughout the night is tricky (not keen on DIY options); not sure how I’d physically couple accessories such as a guidescope; and I’d worry about leaving the lens out in my garden all night when I might need it for paid work the next day. With a dedicated telescope I could just keep the camera permanently attached, which would also be easier. Some days I think I'm mad to consider a telescope as I have lenses; but the next day I'll think that a dedicated telescope is obviously the way to go!

Camera
Being in a city centre, using my unmodded Nikon camera is a no-go. I’d like to go cooled CMOS. I like ZWO cameras, plus am thinking of getting the ASIAIR Pro to make everything easier. Now comes a biggy… although I got good use out of my mono CMOS and filters, it was a bit of a faff dealing with all the different filters, matching calibration frames, and then the processing afterwards. I was capable of doing it, but I’d prefer something simpler. Now I’m hearing about filters such as the Optolong L-eXtreme and L-eNhance, and am wondering if one of those coupled with, say an ZWO ASI 294MC-PRO or perhaps an 2600MC-PRO could be a winning combo. Just to stress, I understand that all things being equal, mono plus filters would be better, but ease of use and consequently fun factor are critical here! But would I be able to take better photos than I was previously?

That’s a splurge of my current ideas. Any and all thoughts would be appreciated, and I’m definitely open to being challenged on any assumptions I may have made that you have a different viewpoint on.

Thanks!

-Lee

Thanks for the info -- those lens controllers in particular are the kinds of things I was imagining, and I had no idea they actually existed! Shame they're currently just for Canon.

On 29/07/2020 at 20:09, Sp@ce_d said:

If you've already got some nice lenses why not try them first anyway. You could rig up a motor & belt drive fairly cheaply.. less than investing in a scope.. to see if it suits you.

That's a fair idea, the reason I haven't just tried it yet is that I don't have a suitable camera to use. My inner-city skies rule out my regular camera. What I'll do is let these ideas swim around my head for a while, and then start a new thread about a whole imaging set-up that might fit the bill. 

Thanks everyone for the replies, you're all awesome

Thanks, all good info!

2 hours ago, david_taurus83 said:

What we your plans or intentions and maybe we can give specific advice.

I've previously had an imaging rig -- telescope, mono CMOS, filters, etc. I sold all of that due to a lack of time for the hobby, and am tentatively pondering a return sometime in the future. I reckon I'd go down the cooled CMOS route, and a key question will be: telescope or camera lenses? I'm a photographer and have some nice Nikon lenses. But 'scopes like the WO 61mm seem like camera lenses designed for astrophotography, so may be a better choice. My old rig had an EAF, and I liked how that took care of focussing, and kept everything in focus all night. So this thread is just to figure out if such a thing is possible with camera lenses

2 hours ago, wxsatuser said:

You can easily focus using 10x liveview and a high ISO.

You should be able to see stars and the correct focus is a small window where the stars are sharpest.

Thanks for the info, but what I'm specifically wondering is whether that focus changes over the course of a night's observing. Or, considering camera lenses are often wide-field compared to telescopes, does an image essentially stay in focus all night?

If adjustment is needed, do you need to manually repeat the process you described every hour (for example) to maintain good focus? Or are there automated ways of doing it (such as vlaiv suggested). From your sig I see you use a Samyang lens, so I expect you've got first-hand experience in this!

On 27/07/2020 at 20:22, david_taurus83 said:

APT can control a camera lens if it has autofocus.

Thanks for the info, that's interesting. Presumably APT communicates with the lens via a cable connected to the DSLR camera? So this wouldn't work if using a dedicated astrocam?

Very helpful, thanks for the info!