smr

ok thanks. I'm thinking I might just ditch my astrozap dew heater and buy a usb one if I'm going to buy the usb hub, means one less cable going into the dri-box.

Will it leave a mark on the mount then? If ever I wanted to remove it ?

£40 for Startech 7 port on amazon, £55 for the metal version. Is it worth paying the extra for the metal version ? I'd probably just velcro whichever one I get to the mount and leave it attached so I'm wondering if I need the metal one or the plastic version will suffice.

Just now, RayD said:

Most of the better ones like Startech actually don't come with a cable, you use your own, so you can choose what length you need.

Duh yep just realised that !

Ok thanks,

A lot of these USB hubs have very short cables. Do you use an extension USB cable to connect to laptop ? 

5 minutes ago, tooth_dr said:

Go with the 5m cable.

I use a star tech 4 channel hub, metal case, reliable item. An astro hub would be a good investment. I have a V3 Hitec Astro MHP and it controls power and usb, plus focuser and dew heaters. 

Yes an Astrohub would be nice, just looking at some powered usb hubs at the moment. Just trying to figure out how many ports I need...

1x DSLR
1x Guidecam
1x Dew heater band (one is USB)
1x EQMod cable

So a 4 port should do ok. If i get a dedicated astro camera then that replaces the DSLR. Can't think of anyother USB powered things I'd need to connect.

Would it be ok to get a magnetic USB hub if I can, or would it not be a good idea to have something magnetic stuck onto the side of the mount (with the electronics etc. inside)

Thanks for the replies guys. Will order a suitable USB Hub, just need to work out a way of fixing it to the mount then. 

I'm in the process of buying an EQMod cable and I'm wondering if there are any disadvantages of buying a 5m cable over a 2m cable. Is it the shorter the better with these kind of cables ? I wouldn't want one that's 1m though as that's too short.

I think if I bought a 5m cable I'd be able to use it on Holiday at my family's holiday home - mount outside and 5m cable from mount to laptop inside caravan etc. I guess I could just loop up the rest of the cable when I'm at home which isn't needed?

Hi,

I need to tidy up my cables and do some cable management really. What's teh best way of doing this? I need to buy a USB Hub anyway as I've ran out of USB ports on my laptop and have an EQMOD Cable coming in the post. 

Is there a good reliable USB hub to buy to attach to the mount and what's the best way of doing that?

Here's how it looks at the mo

3 minutes ago, steppenwolf said:

 

You will need an external IR reject filter as without one you will get star bloat and other issues! If you do go ahead, I wish you luck and the only advice I can give you is to work in the cleanest air conditions that you can and take it slowly!

Thanks, so if I wanted to add a Ha filter at some point how could I go about that, clip in Ha and an IR in the optical train ?

ok thanks guys, I think I'll give it a miss.

Hi all,

I'm really wondering whether to buy an astro modded DSLR now as I was going to buy a dedicated astro camera but the cheapest if I was going that route would  be the 294MC Pro and that's around £1k, and that's been put on hold for a bit with the current situation.

But I am so frustrated at not being able to image Ha objects that I'm wondering whether to buy a cheap DSLR for £200 and mod it myself. I think I should be ok with that as I can disassemble a laptop completely and put it back together so it's basically not much different to that.

So if I were to buy a Canon 700D for that kind of price, and mod it myself, presumably that just means following one of the many guides on the Internet and removing the IR filter? And that's the mod done? 

Are there any disadvantages to this as I have heard that star bloat can be a problem when a DSLR has been modified ?

I'm not bothered about the autofocus not working as to be frank, I have never used autofocus in two and half years of doing AP.

Any other disadvantages ?

And also if I do go ahead and remove the IR filter do I need to then buy a filter for the DSLR to be able to use it properly for AP ( I think I've read that you need a UV/IR filter or something )

Many thanks for any advice!

Nice image indeed. Apologies for sounding thick but how does using a remote obs work? Do you just slew to the target remotely and set off an imaging run or is there more to it ? Just asking out of curiosity.

I wonder what Bortle scale this is shot from? 

Nice, new one to me.

1 hour ago, symmetal said:

Hi smr,

Having perfect polar alignment does not mean your guiding will necessarily be improved. Perfect PA is not actually necessary if you're guiding and depending on the mount performance can even be detrimental. If you are imaging unguided, then getting PA as close as possible is what you want. If guiding, small PA errors will be corrected by guiding, unless the PA is well out when you will end up getting the image rotating around the guide star during the exposure leading to elongated stars in a circular pattern, increasing the further the distance from the guide star.

For mounts with Dec backlash as most mid price mounts have, it can be beneficial for the Dec PA to be slightly out by a few arcminutes so that the Dec is always guiding in one direction to compensate and so the Dec gears stay meshed. With perfect PA, the Dec axis will end up sitting in the backlash area and Dec corrections may  seem to be ignored until the backlash is taken up, leading to the Dec cycling between fairly large +ve and -ve errors every 10 seconds or more due to the actual corrections being many seconds behind the command corrections.

Dithering in Dec can upset this beneficial constant Dec meshing if it dithers to the other side of the backlash area. The mount can then take a while before the Dec settles down again.

Getting a good guide star is important. I find at times the guiding is good and then half an hour later is all over the place and changing the guide star helps. The sudden changes in RA error you're seeing on your graph is due to the guide star shape changing between successive guide frames due to seeing, and PHD2 trying to correct for this. Getting the right guide exposure and star shape selection is a bit of a balancing act and will probably need changing throughout the session. I find stars below 100 SNR generally give worse guiding while those much higher are often clipped with flat tops. However, I find that clipped stars can sometimes give better guiding than the normally preferable sharp spike star profiles, as their overall profile remains more constant.

It may be worth running PHD2's 'Guiding Assistant' for a few minutes to see if that recommends any changes. It will also measure Dec backlash if you tick the box.

Alan

Thanks very much for that detailed reply Alan. Explained very well.

Just now, gasdoc said:

Thanks everyone,

@smr I use the sigma a lot for my standard DSLR stuff (wildlife etc) so selling not an option

This was an attempt to see if I could get away without the added expense of a bigger refractor ( I am obviously lusting after an Esprit 100 but v difficult to justify to wife 😬 even after playing the "I need the stress relief during COVID" card [I'm nhs]).

 

So I guess I'll try with the SCT tonight, cross fingers, and see how that performs otherwise its penny saving time!

 

BW

 

paul

Good luck.

You've got a sturdy mount that's for sure. But just looking at the shot with the Sigma just looks like it undoes the sturdiness of the Mount. Doesn't look stable to me. 

You might be better off selling the Sigma for AP, there's a heck of a lot of lens elements the light is going through before it hits the sensor. I had the same lens but sold it to buy a refractor and then stuck the guidescope on top of that.

It's 1.20" total now as I'm writing... I thought it would be better given the 'Excellent' PA according to sharpcap. I'm wondering if the az and alt bolts are tight enough when locked but they seemed to be.

Thanks guys. Only about 10 subs in at the moment on M101 as I had a right game trying to get the mount star aligned this evening for some reason. Just went way off when slewing to stars so I had to turn it off a few times until it started working properly.

Obviously took longer in that I was trying something new tonight as well with polar alignment. The graph did look better than this earlier on with a flatter line for both RA and Dec but the stars are round in 180 second subs. I think it's definitely an improvement but I've just got to get better at refining the process.

9 minutes ago, symmetal said:

Yes, as the other Alan says it's very easy to use. The guidescope doesn't even have to have the NCP or Polaris in view though it needs to be reasonably close so that its plate solving and adjustment indicating can work. A wideish FOV is also needed on the guidescope again to enable platesolving. Your Starwave should be fine. You need your Sharpcap display screen next to the scope so you can see the results as you make adjustments. It will select a star (not necessarily Polaris) in your FOV and indicate on the display where the star needs to be moved to by altering the mount alt and azi bolts. That's it. 

Worth the small cost just for this feature alone. 

Alan

Sounds great! And should give me much better guiding than before all going well? 

So if I understand it...

After I've roughly aligned Polaris in the HEQ5 reticule, I park the Mount in home position? 

When it asks me to rotate the RA through 90 degrees do I then lock the RA or just leave it unlocked? 

3 minutes ago, Vixen4eva said:

Its brilliant and very easy to use. The hardest part i find is the adjustments on the mount......the HEQ5 doesn`t have the best ones!!! As long you have a reasonably sensitive guide camera your good to go.... Can`t comment on the Polemaster as i`ve never used one so can`t compare...

Regards

Alan

Thanks very much Alan, you make it sound easy. I'm looking at it overly-complicatedly as usual !

Funnily enough I was looking at my Iris data earlier. I got 3 hours in November. Definitely can see some nice detail and nebulosity but not much of the dust clouds you mention either. I think you'd need 15+ hours under bortle 5/6 to start getting good data on the dusty regions in Cepheus.  I'm dithering whether to get more data on it or shoot a Galaxy instead too. It'll be higher in the sky from 12am onwards, and higher earlier on from May/June. But then again my North facing side of the back garden is much darker than the South, no light pollution to the North so its a nice area of the sky for me.

Hi,

With a few clear skies coming up I thought it would be a good opportunity to try and get better alignment and guiding. I was looking into buying a polemaster, but then stumbled across a post about sharpcap being able to do the same thing, for a tenth of the price (£10 for the pro version per year)... I remember seeing something mentioned about sharpcap a while back, think it was bundled with a product I was looking at and someone mentioned being able to use it for PA.

So, is it relatively easy to set up and use? I understand I need to get reasonably accurate PA first manually, and then I should be able to use Sharpcap with my guiding camera for precise alignment and guiding. 

Hi,

Is the QHY8L still a good Camera by today's standards, one on the market for around £500.

Hi all,

A photograph of the Moon on Sunday night... 85 percent Waxing Gibbous.

Moon by Joel Spencer, on Flickr

Video on it here;

I will be using my DSLR. So just stick to taking single frames?