Borderline Bob

Don't know what it is but I think images of the bubble nebula are fascinating and this one is stunning.

They say beauty is in the eye of the beholder and I think this is a beautiful image.

QHY5111462C Camera and Expansion kit but we need to keep it quiet.

2 hours ago, The Lazy Astronomer said:

I can't make a personal recommendation (I haven't done any planetary for a couple of years now), but the 462mc seems quite popular. ZWO have recently released a whole new bunch of cameras though, so not sure what the general consensus is these days. You could drop a message in the planetary imaging section for some solid advice. 

Thank you, will probably go with the ZWO ASI462MC  as seen quite a few youtubes reviews and its just in the price range I am not that unhappy with.

21 minutes ago, symmetal said:

As you're using a filter drawer with the flattener, then the easiest way to maintain the spacing is to put a clear glass filter in the filter drawer when you don't want a specific filter. This avoids you having to remove a spacer to compensate. A UV/IR cut filter also called a luminance filter is commonly used as a 'clear' filter as it has the benefit of blocking out of focus IR wavelengths from the sensor.

Alan

Thanks Alan sounds an ideal solution.

17 minutes ago, Cosmic Geoff said:

The ASI120MM will work, but the results will be mono (OK for the Moon).  

I used an ASI224MC for a couple of years.

I now use an ASI462MC which works well. It has a smaller pixel size than some other cameras (+less need for a Barlow).  There are probably even newer cameras worth considering.  You will need a UV/IR cut filter for this camera, and you may as well buy an IR-band pass filter as well for IR imaging.  You will also need an ADC (atmosphere dispersion corrector) for best results.

I use an alt-azimuth fork mounted SCT. 

That's great, thanks Geoff

1 hour ago, The Lazy Astronomer said:

No wedge required for solar system imaging, and no worries about anything limiting exposure time either - you will want to be using very short exposures (in the 10's of milliseconds or lower).

You don't want a focal reducer either; depending on which camera you buy, you may want the opposite to a focal reducer - a barlow or powermate - to increase the f ratio. You'll see different values given for this, but I use:

target f ratio = pixel size (um) × 5

The 8" should provide some good results once you get it all up and running though - it'll be worth it!

Thats great, thank you. Any recommendations as to the camera, I do have a ZWO ASI 120MM Mini USB 2.0 Mono Camera that I use as a guide camera in another ota but I am not really a fan of it and would like something a bit better. 

28 minutes ago, symmetal said:

Back focus spacing is only important if using a field flattener or coma corrector in your imaging train, as an exact distance is required between the flattener/corrector and the image plane for them to work correctly. Adding a filter between the flattener/corrector and the camera will increase this critical distance due to refraction through the filter so an extra mm or so spacing is necessary. You;re right that if the filter is removed then the extra mm spacer would need to be removed.

Getting the spacing right is more critical with larger size sensors. With smaller sensors the spacing distance is not so critical and the change when adding a filter is likely not worth worrying about.

If not using a flattener/corrector them there is no critical back spacing requirement, so as long as you can focus the image then your're fine. Adding a filter will move the focus point back a small amount but your standard focus knob will take care of that for you. 🙂

Alan 

Thanks Alan, yep there is a field flattener in the mix.

About a year ago I bought a Meade LX90 8" ACF for the Perfumed Ayatollah, she though hasn't really been interested so I thought could use it for solar system/planetary imaging, is this realistic. I don't really want to change the fork arms for the wedge setup and realise I would be limited to length of subs etc and truth be told I don't want to spend a fortune. Was hoping perhaps in the purchase stakes I would need obviously the camera, some spacers and a focal reducer. Any thoughts would be great.

Thanks in advance.

New to AP and a bit confused (what's new), if I put a filter drawer in the train I understand I would need to add (generally) 1mm to the train for back focus purposes when inserting a filter, do I then if not using a filter in the drawer remove the 1mm spacer. However as I'm typing this I do feel a Homer Simpson "d'oh" moment is imminent.

Thanks in advance.

5 minutes ago, CraigT82 said:

Get sharpcap pro and run a sensor analysis and then the smart histogram tool, will give you good info on what’s best for your particular sensor

Ironically the license has not long expired on Sharpcap, I did initially connect to Sharpcap but was only getting a white screen and thought I had problems with backfocus. The OTA is a SW Esprit 80ED and it seems their is an "old version" of the field flattener and "newer" version and each has a different spacer size.

13 minutes ago, symmetal said:

You want to set the camera gain to where the HCG (High Conversion Gain) mode is enabled. This ensures lower read noise with little loss in dynamic range as shown in the graphs. It's also around unity gain which is recommended when starting out. There's debate as to what the gain setting is where HCG mode is enabled with quotes of 117, 120 and 121. From the graph it's a bit hard to tell but the difference between the gain values is minimal so gain 121 to be safe as scotty38 suggests.

It's easy to find out though, if you wish, by just taking a bias or a short exposure dark image, ie. exposure with the camera front cap on, at different gain settings. Look at the image statistics readout in your capture software and check the SD (Standard Deviation) value which corresponds to the noise in the image. As the bottom graph indicates the read noise drops significantly at the gain setting (and above) where HCG is enabled. The SD of the image will also drop significantly at this point.

I assume wbr is white balance. This isn't used in astro cameras as you want to record the raw data from the camera before any manipulation. Any colour adjustments are done later during stacking and processing.

Optimum exposure depends on your level of light pollution and 'speed' of your scope. For an f5 or f6 scope in moderate light pollution around 3 mins is a reasonable starting point. If dark skies with low light pollution around 6 mins. For an f2 scope around 1 min exposure. It's all to do with exposing until the noise from your sky background is significantly higher than the camera read noise, around 5 times larger is a commonly used figure. If you want more details on how this is determined and why feel free to ask, but the exposure examples given are fine for starting out.

Leave the camera offset at the default value. It's generally set a bit higher than it need be, but that's not a problem. It's when it's set too low and you get black clipping in your image, that it's bad. 🙂 

Alan 

Thankyou both.

I mentioned white balance because when I first connected to ASIAIR + I was just getting a white screen and initially thought my backfocus was out but putting my hand over OTA and I saw an image and had to muck about with the gain/exposure and to a small degree wbr and wbb in the ASIAIR before I got any picture. I give a gain of 121 a go and do a lot more test shots.

Thanks again.

Just starting out setting up with ZWO ASI 294MC-PRO connecting via ASIAIR plus, setting up during the day to make sure focus, gain etc. Does anyone have any recommended starting out settings as to to gain wbr, exposure etc.

Thanks in advance

Replying to my own post:

If you don't want to go with the mucking about with tube rings then fitting a longer dovetail works (and cheaper), I went with the 11" ADM https://www.firstlightoptics.com/adm-vixen-type-v-series/adm-vixen-style-universal-dovetail-bars.html

I recently removed the foot on the Esprit 80, there is a thread on here that I followed:

Also I didn't need a spanner or ratchet on the nuts inside the ota, just pushed down on the nuts with a finger (that may work for you). My intentions was to replace with rings and initially went with  Sky-Watcher Tube Mounting Rings Mounting Rings Size: 101 mm. These fitted fine but was told by FLO that "the cast alloy Skywatcher rings then they are not really suitable for bolting other accessories on top.

The alloy is very soft and the 1/4" threads on the top of the ring easily strips."

They (FLO) recommended https://www.firstlightoptics.com/tube-rings/stellalyra-101mm-tube-rings-for-sky-watcher-esprit-80-evostar-80100-ed-startravel-102-and-evostar-102.html with this vixen saddle https://www.firstlightoptics.com/adm-replacement-saddles/adm-vixen-style-saddle.html ADM Tapped (sadly still out of stock)

You would still need riser blocks though

Stunning

The perfumed Ayatollah wanted wifi in her cabin and she installed one of these https://www.amazon.co.uk/dp/B077HTZ4TT/ref=redir_mobile_desktop?_encoding=UTF8&aaxitk=7404319f47bf9c063099725aab1bf69b&content-id=amzn1.sym.e4f48e2a-4f4e-495a-a95b-34f114e19c84%3Aamzn1.sym.e4f48e2a-4f4e-495a-a95b-34f114e19c84&hsa_cr_id=8120727250702&pd_rd_plhdr=t&pd_rd_r=b56d7cac-7a52-4a98-a2af-a69644eebd60&pd_rd_w=Ip2wF&pd_rd_wg=2wYY9&qid=1656503728&ref_=sbx_be_s_sparkle_mcd_asin_0_img&sr=1-1-fd947bf3-57d2-4cc9-939d-2805f92cef28 it works really well.

PS Cabin is about 30m from the house

HI Everyone,

New here and to Astronomy (oldish to life), I have a SW Esprit 80ed with a SW Evoguide 50ED as guide scope. I really dislike the vixen dovetail foot on the scope and want to replace it with tube rings? FLO has suggested these for the tube rings https://www.firstlightoptics.com/tube-rings/stellalyra-101mm-tube-rings-for-sky-watcher-esprit-80-evostar-80100-ed-startravel-102-and-evostar-102.html, the problem is though that the lugs on the "boatwheel" interfere with mounting the guidescope and the ota. Could someone suggest a workaround as I don't know enough about what is available and even what they maybe called as very new to the hobby.

Many thanks

PS First picture in this thread shows the "lugs" on the "boatwheel".