Mr Thingy

Does anyone know if the fitting is the same between Canon EF, EF-S and EF-M lenses? I'm trying to figure out if the adaptors for fitting Canon lenses to CMOS cameras will work for the EF-M lenses. e.g this: https://www.firstlightoptics.com/adapters/skywatcher-dslr-m48-ring-adapter.html The EF-M lenses are cheaper and are for the smaller format, which seems like it would suit my ASI 183 sensor. TIA

Many thanks. That's helpful.

Hello SGL-ers! Looking for some advice from you kind, knowledgeable people. My HEQ5 is taking an eternity to arrive (1/4 of a year so far) and I'm not convinced it will even arrive in Dec so I'm exploring options that will allow me to take some snaps in the meantime. I was considering buying a camera lens for some static-mount, wide angle imaging, to attach to my ZWO ASI 183 GT. I can then use guided/unguided when the HEQ5 arrives. I was thinking about a lens with a FL of about 35 to 50 mm. My first question is whether it is suitable to get a lens for the smaller sensor size (e.g Canon APS-C)? My CMOS camera has a diagonal of about only 16 mm, so it seemed that with a standard lens for full frame (35 mm), my sensor would only capture half of the image. My second question is how best to attach to my mount. Can you get a bracket to attach to the lens (maybe a mounting ring from a scope would work)? Last question: is there any notable difference between Canon or Nikon lenses? Is one better suited to AP than the other. I was looking at this (and the 35 mm equivalent): https://www.intro2020.co.uk/Catalogue/ProductDetail/samyang-50mm-f1-2-csc-canon-m?productID=caaea451-50fb-4d26-8ed6-f4718d906c5d&catalogueLevelItemID=376dc0a0-f0a7-422d-a66b-27282b4cce5b All other comments and recommendations welcome; come earn yourself some of the reputation points I know you love! TIA -Thingy-

I bought an adaptor and a bunch of extenders and now everything works perfectly (I also learned a wee bit more theory on telescopes and focus) 😀 Thanks for all the great advice!

Thoroughly exciting item received today. So exciting that I will share with you all. The sad part is that it's going to sit idle until my HEQ5 finally turns up (ordered mid-Aug) 😪. Dear China, please make and ship my HEQ5 ASAP. Tyvm. -Thingy-

FLO will love me this year. This hobby is expensive!

Awesome. Thanks a lot.

That helps immensely. Thanks for your explanation. I knew I'd have some silly questions sooner or later! If I'm not using an FF, do you know how much extension I need to achieve focus? Is that still 130mm?

Thanks. I think I'm missing a key bit of theory here as I'm still confused. I thought that it would simple be a case of finding the distance behind the scope where the image is in focus. What is the 130mm position then? Is it the point where the image is the correct size for the sensor? Then how do you set a focus position? Maybe there is a website that explains this? Cheers

Thanks @alacant Do I understand that with the TS flattener I would still need extenders to reach the 130mm back focus? What would you use for that?

Everywhere is sold of field flatteners at the moment. Looks like my mount won't be the last thing I'm waiting for before I can start imaging 😓. Anyway, thanks for all be the great help. Have yourself some rep points for your troubles 😄

Do you have to remove the bracket for the 2” nosepieces to find the thread? I tried earlier but it wouldn't budge and I didn't want to force it. Cheers

Unless I'm missing something the 72ED doesn't seem to have a screw thread at the end of the focuser. I assumed there would be.

Which generic flattener/reducer do you use? I notice that FLO have a 40-60 working day wait on the dedicated reducer for the 72ED. My HEQ5 had the same estimate when I ordered in mid-August and that's not here yet, so it's not looking good for the reducer 😓.

Ah! Ok, good to know. Thank you. In that case I will be needing a focal reducer. No sense in buying umpteen extenders for temporary use. Any idea how the focal reducer attaches to the scope? There seems to be no thread on the scope.

I thought I was missing something obvious but it looks like just a bit of tinkering is needed. Thanks to all.

Pretty sure this is a stupid question but I have to be asked as I can't figure this out myself 🤔 I have a SW Evostar 72ED and a Guidestar 50ED that will be the guidescope. I don't want to attach the 50ED using the finderscope shoe as I foresee a scenario involving gravity, the floor and some expensive gear, so I want to mount directly onto the top of 72ED. However, I can't see how this should be done, so I'm looking for tips. The ED has a dovetail - do I need to replace with a different plate? Thanks in advance kind people of greater brain power than my own 😉

Thanks. It's helpful to know that I need 55mm of backspace. The extenders from the camera are only 28mm combined and I lost half of that slotting into the 2" hole. I need to figure out a means to screw the m48 extenders directly to the scope without inserting in the 2" slot. I suspect more money is needed to find s solution. This sport is a money pit (as if I didn't realise that already!)

I have various extenders and adaptors but I don't seem to have enough to achieve focus with the 72ED and my ZWO ASI183 GT. Can any owners of a SW Evostar 72ED advise what extenders and adaptors you use to achieve focus? Please note that I don't yet have a field flattener fitted - I will get one fairly soon but for now I need a solution without one. I was also hoping that there would be a screw thread for secure fitting between scope and camera but the 72ED only seems to have a 2" fitting for diagonals, etc. Thanks for any advice you can provide.

Excellent idea. 😀

I've no doubt they will replace it; and surely with something more appealing. I too am not a big fan of sycamore, but the shame is that it's old - at least 50 years I would guess - and any replacement will take a long time to reach the same canopy size and leaf density, not to mention the same CO2 intake. Though I won't miss the tonne of leaves that somehow seems to land in my garden rather than theirs each autumn.

I have a slightly different quandry, but still related to the topic of nature. My neighbour has asked if we have objections to removal of a massive sycamore tree from their garden. I have mixed feelings as this thing blocks my NE view but it's also a great habitat for bird and insect life. Such a massive tree can't easily be replaced, of course. Since objects tend to rotate into view from the NE anyway, the tree isn't much of an embuggerment for me when observing. It's ultimately their choice, though I could in theory contest during the planning application, but I think I will just tell them that it would be a big shame to remove it and let them make the choice. Hoping they make a sensible decision.

Ha yes! I know the feeling. I just ordered the EAF, so now my rig will be fully automated 😀. I can now cross one more thing off my shopping list. My wife will be so pleased.

Ah yes, the flattener. That's on my ever-growing shopping list of astro gear. I also plan to get an EAF to attach onto this.

Thank you. I plan to play with it at the weekend and figure out if I need any extra extenders for my camera.