Adam J

I sense sarcasm in that statement.

I can only respond by saying that the size of sensor required is a function of your focal length and the size of the object you are imaging not just the size of the sensor. For example during galaxy season I can drop a fare amount of FOV and still image my target and some more even on a relatively long focal length scope saving a large amount of storage space. At the opposite end of that equation I have the ASKAR 180 and most targets will fit on the 533 sensor at that focal length on my mobile rig. I could also use a hyperstar at F2 without vignetting 1.25inch filters of worrying about my image corners. Adam

Mono, I dont even have to stop and think about it. It wont be perfect but it will have much less CA than in an OSC. Adam

So looks like we will very likely be getting a mono version of the ASI533MC Pro in the not to distant future as a mono IMX533 sensor has now appeared in SONY's CMOS sensor catalogue. https://www.sony-semicon.co.jp/products/common/pdf/IMX533CLK_Flyer_ver10.pdf https://www.sony-semicon.co.jp/e/products/IS/industry/product.html I predicted its release over a year back in this thread and nailed it totally as the end of 2021 when people told me there was no use case for such a sensor. Apart from being a little smug about being proven right I am also very happy about this as I was hoping for this sensor as when it turns up in an astronomy camera I will be making a purchase for use in my second rig. # Adam

SO I CALLED IT! Its the end of 2021 and just take a look at what SONY has released! https://www.sony-semicon.co.jp/products/common/pdf/IMX533CLK_Flyer_ver10.pdf https://www.sony-semicon.co.jp/e/products/IS/industry/product.html A MONO version of the IMX533 sensor, just as I promissed you all back in November 2020. EVERYTHING IS NOT GOING OSC..... #Smug Adam

Yes that's the ideal. But not always possible. I did find my pva method to work well, it's not load bearing after all. I make mine 40cm X 40cm though so a much larger contact area.

So a crack at the join at the base, this happened to me you need to add PVA to the mix and a layer at the join, especially the case with rebar I find as concrete shrinks as it sets and if a piece of rebar is going though it then it can actually pull itself up on the rebar and leave a tiny gap at the join. Differential shrinkage between two layers spanned by the rebar that is no going to move itself.

If you can get an image in daylight then its not likely to be the camera. Even out of focus if you are seeing the image dim as you move your hand over the front of the scope then the camera is working. After that the only remaining thing it can be is that you are not reaching focus. You could try manually pulling the camera backwards from the end of the eyepiece holder on the diagonal but in the end its most likely you dont have sufficient outward travel.

Do you have a diagonal that you would normally use with your scope? If so the diagonal increases the light path and effectively extends the focus travel outwards like an extension tube would, try putting the camera into the diagonal and attached to the scope and see if you can reach focus then. If that is the case you may want to get a 1.25 inch extension tube so that you can image without the diagonal. Adam

I like the in your face version.

Throw up a guide graph so we.can take a look?

No it's not pointless it still reduces guiding errors in the final drive to have a larger spur gear. But I suspect that the guiding resolution is the same.

1.25 inch too.

It's dust close to the camera, probably inside the DSLR on the front filter.

I would disagree, the RA spur gear on the 35 is larger 180 teeth than on any of the EQ5 variants 144 teeth, larger spur usually translates into more accurate tracking as small errors in the gears will give a smaller angular movement on a larger diameter gear than a smaller one. Also guiding resolution is higher. The only way to get better is to go with the HEQ5 pro. What I would say is that I have owned a few Skywatcher mounts and have never got one that did not need tuning out of the box. I mentioned the 130pds. But really if he is imaging with less than a Heq5 I would try to keep focal length under 460mm it 80mm F6 refractor. I only mention the 130pds as he wants to do visual to but that's a hard requirement on a budget mount.

Try actually getting hold of one of those though.

130pds on a eqm-35 is imaging is more important than visual.

Ok so the fist issue is that your backlash setting is way too low. The second issue is that your initial step size needs increasing by at least a factor of 3x (maybe even more) what you are using here. The final issue is that you are using a linear fit to solve the focus position and I would recommend hyperbolic only. Adam

Cant see the image on my PC, maybe try posting it as a JPG. Got some experience in this area if you can.

Any chance of a closer look at the optical report?

I think it matters more who you purchase from as opposed to which one you buy. I have seen fantastic examples of both scopes and also optically questionable examples. Personally I would go with the GT81 but only because I dont like the little foot thing on the Esprit 80. Tube rings are the way to go. It you could stretch to the esprit 100 then I would recommend that without hesitation. Also have you looked at the stellamira 90? It seems great value at that price which is very similar to the scopes you are looking at and guarantees 0.95 stehl ratio. Which while not the be all and end all. It is better than the other two which promise nothing beyond diffraction limited performance (but normally deliver much better). Adam

I think that you have to make some compromises if you want a truely compact travel imaging setup. My solution is the ASKAR FMA180 and yeah its not perfect in terms of CA / poly strel (not sure what other aberrations you mean) but it can be corrected in processing with the use of a L3 UVIR filter too unless you really pixel peep. The reality is that with triplet refactors below F6 you will always have to trade between poly strel and CA and you will not get a perfect result. You need to go to a more optically complex design to get better performance below F6 and it gets harder as aperture gets bigger. I have a friend with a WO GT71 that delivers good results, perhaps combined with a 1.0x corrector as opposed to a reducer this will give you the performance you are looking for? https://www.firstlightoptics.com/william-optics/william-optics-gt-71-ii-2019-checked-tuned.html In the end no budget if going to defy the laws of physics, you cant have it all. The only other thing that comes to mind is a TV-76, FLO have an ex demo avaliable? Combine with a 0.8x reducer. https://www.firstlightoptics.com/offers/offer_tele-vue-76mm-f6-3-apo-refractor_187502.html Although i would still go with the GT-71 if it was me. Adam

Would this not require that the Lum exposure length is identical to the RGB filter exposures? If not I guess you need to add some sort of scaling factor as L will not = RGB. Not sure if I am the norm but I tend to use shorter exposures for L than RGB. Adam

The physics of mono Vs OSC has not changed. Both have gotten better equally. It's just OSC has now improved to the point when people are willing to settle for the results, nothing wrong with that I may get one on that basis at some point. But if I want to get the very best image I can it's going to be using a mono camera.

For astronomy more so than anything else I would simply say if it's not broken don't fix it.