david_taurus83

The microlensing is hit and miss. My WO GT71 and Flat6AII seem to control it well. See below. It's there but not in your face. I have another scope and flattener and it's more pronounced on that but I've only seen it on the brightest of stars like Capella, Vega etc. More so on the red and Ha filter.

Most of us use this image as the go to reference when trying to sort out the spacing for for a nice flat field. Has anyone actually had any success in replicating it? For example, you have streaky stars as in the top image, you add a spacer and all of a sudden you are too far away and you get the opposite effect in the bottom image? So you space to somewhere in the middle to get nice round stars?

I have to say I have my doubts about it. Last night I spent 5 hours meticulously adding 0.25mm spacers to my Starwave 102EDR with TS Optics Photoline 3 inch 0.79 flattener. The recommended back space distance for this scope is 56mm. The minimum distance I can produce with the various bits and bobs I have here is 56.1mm. I started off with 56.6mm as I have 2 filters and the sensor window in the light path. I went all the way out to 62mm in 0.25mm steps and almost everytime I was still getting the elongation in the corners like in the top image. Sometimes I would get ok in 2 opposite corners but streaked like the bottom diagram in the other 2. It just seemed to generate any old random effect. It really is enough to drive you insane!!

Of course, at what point did I arrive at my best result? Yes, you've guessed it. At 56.1mm without any extra spacers at all.

Top left

Top right

Bottom right

Bottom left

Centre

This is a stack of 10 x 30s subs, unguided. This is the method I used to evaluate all the possible spacings, to try and achieve an average representation of the stars.

Clearly adding spacers is not beneficial. The only other way is to decrease the distance between flattener and sensor. But looking at the bottom corners it would appear I am already tilted too close.

Should I just leave it the hell alone?

5 hours ago, Viktiste said:

Why not? We're not imaging in rainy weather.

Because its dangerous. It doesnt need to rain. We often image in wet, damp conditions.

They are the correct exposure so no issues there. They are clearly causing you issues though as they have a ring type artifact around them. Any ideas what could have caused this?

Hold down shift and then press connect and it should give you the connection options again.

Check your PA with Sharpcap  carefully. If you carry out an adjustment without pressing next at the right time it can mess the result up. I done it myself a few weeks ago. If you follow the guide carefully, get an excellent result, swing back to home before closing Sharpcap to confirm your still getting a good result. As above, your Dec error is worse than your RA. If you were well aligned Dec wouldnt move much at all. The belt driven EQ6 is a good mount. It will easily guide within 1 arc second.

Personally, I'd uninstall PHD and reinstall again and set up a fresh new profile. At least this can be done during the day.

Have you tried to hardware map your devices? Also, I seem to get less issues if I use the web manager to setup a profile and map the serial ports in there as well.

Does it work on it's own plugged into the laptop?

You dont need a guide scope at all! That combo should be absolutely fine. The only thing extra you'll likely need is an intervalometer for setting long exposures OR a USB cable if you wanted to control via a laptop.

Edit: Just to point out, the longer the focal length used and the more difficult it is to take longer exposures. Your 200mm lens might be the upper end of what you can get away with without guiding. Start off with 30s exposures and see how you get on. If Good balancing and polar alignment are key. If you get no noticable star trails then you can try longer exposures. It's a bit of trial and error getting started.

My main gripe with APT is the histogram will only give you a minimum and maximum ADU value. When shooting flats we look for the mean value so they cant be done manually in APT. You kind of at the mercy of the Flats Aid.

Can you post up a single flat and the master flat generated by DSS?

I also shoot 15 minute subs in narrowband. Get very good results. As Adam has said, shoot some darks and see if they are ok. I use the same settings as you, unity gain, -20 etc. A 900s dark at 50 os should have a median value of around 850 adu. 60 os should be around 950 adu, there or there abouts.

Has it always been like this? Sounds like the same issues I had with my 1600 when I first got it. Image downloads would hang in APT. I blamed my USB hub for ages. Turned out it was my old laptop, Win 7 USB2 only. When I switched to a new Win 10 USB 3 laptop all the issues disappeared.

Hi and welcome to SGL! The Star Adventurer is primarily designed as a portable setup for use with a DSLR and lenses. It can be used with small telescopes as well but might need a very sturdy tripod. You dont need a laptop to use it. It will track the movement of the sky in sidereal rate. I think it also has both lunar and solar rates as well. What kit are you planning to use it with?

I know CCDs are very different to the CMOS type I use but I'd have thought youd have much more signal in the stacks? What do your Ha subs look like?

If one device connects and the other doesn't, you can select the free port and connect to that instead.

What guide scope are you using?

The darks will only take out the amp glow. Try stacking without flats and see what you get?

I thought that type of mount didn't have backlash?

Grabbing another couple of hours on the Iris tonight. Will have 6 hours RGB and an hour L. Hopefully clear next weekend and can concentrate on lots of L. I've already took my flats tonight so as soon as the image plan is finished in half an hour I'm off to bed! Looking forward to sleep!

26 minutes ago, Rattler said:

Yeah I've got Sharpcap. I actually focused using the Bahtinov Aid in APT. I have a Focus Cube so I'm thinking of using N.I.N.A for capture as it has auto focusing.

I never got on with the Bahtinov Aid in APT. Instead I used the Focus Aid and concentrated on the HFR values. If you try it, turn of an stretching of the preview and pick a medium bright star. Zoom in and place the focus aid over the star. Adjust until you get the lowest value. It's essentially the same as focusing through an eyepiece. Try looping for 5 seconds but with a 5 second delay in between so when you adjust the scope has a chance to settle between captures. If you have an autofocuser then APT can di it all for you though you may need to keep an eye on it. I had a 95% success rate with APTs Auto focus routine.

The veil needs dark skies and a low power eyepiece. I'm also bortle 6 and cant see it from home. I first seen it last year under dark skies at a star party. Was using a 200p and 25mm eyepiece with a UHC filter. Was the highlight of the night for me. Was also visible in my 3" frac but didn't pop out as much as with the 8" newt. I have an OIII filter now so hoping to see it again at a couple of upcoming star parties.

Latest is 3.3.4. But the flip is giving me issues. Despite using PHD2, it seems to have reset the guiding calibration even though I have PHD set to auto restore. I dont want it to recalibrate every time it flips. I'm imaging near the zenith!

Are you using the latest version? In the mount tab there is section to tell the mount to flip if a certain angle past meridian. Mine done a flip on queue, but the image plan hung on a download. Had to press stop in the image plan to continue.

I have the Flat6AII on my GT71. Have never ever got perfect flat to the corners. I can confirm however that the quoted distance is very close. I have found that when you are close to optimum, sub millimetre matters. I find it's easier to add spacers than to keep rotating everything. I recently bought some steel shim washers from Spaldings Fasteners. They do M45 and M50 sizes 0.2mm and 0.5mm thick. Have helped me get very very close with a TS flattener on my 102mm Altair.