... and then that moment when you realise you need a filter draw in the light train ... ;-)
@GalacticHunter
3 жыл бұрын
Haha I actually just bought a filter drawer recently just for this reason.. ☠️
@ojinerd
3 жыл бұрын
This is my problem right this second!! backfocus!!
@GarnettLeary
3 жыл бұрын
SvBony makes a really good variable extension in both M42 and M48 thread with a locking ring. Absolutely love it. Best part it’s reasonably priced.
@Neanderthal75
2 жыл бұрын
Bingo. I'm about to buy the M42 size, since I already have the M48. it saves so much headache and frustration.
@christianvulpescu1398
3 жыл бұрын
In addition to the described problems, the 67 mm is a recommendation. Some optics (e.g. field flatners) can derrive from the recommendation slightly. Then the fun begins.
@johnadastra1754
3 жыл бұрын
An electronic digital caliper greatly helps with this process. You can get a 6 inch or 150 mm type for $20-30 bucks or so. Most adapters don't exactly reach the advertised length once you thread them together so a double check is always needed. Plus a digital tool can be zeroed at the backfocus of you camera, e.g. starting at 17 mm, so you automatically subtract that distance when adding extensions or accessories. Thanks much for the tips on full frame sensors. It appears we will all have to change out from M42 threads eventually as the cams keep getting bigger and more affordable.
@zaphus
3 жыл бұрын
I'm literally about to walk outside and try to figure out backfocus with a reducer for the first time, perfect timing!
@CVB_1111
Жыл бұрын
Thanks.
@Chamsdlr
3 жыл бұрын
Nice Video. Helped me a lot
@GalacticHunter
3 жыл бұрын
Awesome, thanks!
@simonwalsh6804
3 жыл бұрын
Wow. I have the mono version of that camera and have been struggling with elongated stars at the peripheries. Based on the image, I have also been too far. This camera is really unforgiving with respect to back focus. Great camera, but needs work! Great video Antoine!
@LogansChristmasLights
3 жыл бұрын
Great video. I've just had to order several different adapters to get correct back focus for two different setups and it certainly takes a while to get the math correct along with working out whether the adapters need to male to male, female to male etc. It gave me a headache :)
@Safestassets
3 жыл бұрын
About time somebody made a video on this!
@Neanderthal75
2 жыл бұрын
I have an adjustable extension tube (M48) I got from amazon. So I don't have to deal with spacer rings and whatnot. Just unscrew it until I get the correct distance. At night, if my star image telling me I'm too close or too far, I can just twist in/out until it looks good. It saves so much time and headache than dealing with different sizes of spacers and extensions.
@anavarrocoquimbo
11 ай бұрын
When you showed the far back focus at 3.28, i saw a rainbow. Is that a sign of bad back focus? I'm having troubles with a sharpstar 0.95x coma corrector, and a quarter of a rainbow, appeared in one corner of the frame. Filters affects significantly on back focus? Lpro and uv/ir cut gave me that, when off it disappeared. Thanks in advance
@wwaqashussain
3 жыл бұрын
First like from Pakistan :)
@stellaquintero5258
2 жыл бұрын
Thank you!
@paulwilson8367
Жыл бұрын
You don't mention the thickness of whatever filter you are using. The formula says thickness of the filter x 1/3 has to be added. My L-Pro for example is 2mm thick, x 1/3 is .66mm that must be factored in. I HATE back focus calculations. NINA now shows you if you are too close or too far.
@Dances_With_Skies
2 жыл бұрын
I have a question which I can’t seem to find a clear answer to. If I don’t have a field flattener, is back focus accomplished simply by turning the focus knobs and moving the tube in and out or do you still have to set the back focus first when the tube is fully racked in or something like that?
@lazy3521
Жыл бұрын
No back-focus is how far your camera sensor is from your lens, your focus would move the lens with it, hence why you need back-focus separately
@figzastro-photography
2 жыл бұрын
Do you know what the back focus would be for a radian raptor and ZWO ASI 533MC?
@kamylko
Жыл бұрын
Very nice video! I have a question: I am using ZWO6200MC which has M54 hole, than is has M48 spacers included. I have reducer with M48 hole, so everything works perfect! BUT... It causes a lot of vignetting. When I don't include one of the spacers, then I can still get a sharp image with a less of vignetting, but stars near the vignette are not pinpoint anymore. Also when I connect camera without reducer, I get almost none of the vignetting. At least during the day when I tested it I couldn't see any. Should I ditch the reducer and enjoy FF sensor? Or is there a way to solve my problem? Also I use FRA500 and Askar reducer dedicated for that camera. Thank you very much for your advice :)
@NielssBohr
4 ай бұрын
with the OAG?
@an35tares
2 жыл бұрын
Hi ! I have a newton celestron (model 32062, f/5, 200/1000mm). I followed the recommendation of zwo for my camera 294 mc pro for back focus. However I'm unable to get the focus with the 55 mm recommendation (Camera, 11mm, drawer filter, 16.5 mm, baader). I must remove 16,5 mm ring to get the focus. My baader doesn't work correctly ! Do you have a solution to resolve this issue ? Thanks
@luisestebangonzalezvarela8904
3 жыл бұрын
Hi, the adapter to the camera, its an adapter m54 to m48?
@ranjitgovindaraj
3 жыл бұрын
Super helpful👌🏼 I just installed an EFW and manual filter wheel and had to get back focus right on my main and portable setups... Lots of spacer😠 I hate back focus... Do you also take into account the back focus when adding filters ? Like I read there’s a 1/3 thickness rule... Let’s say a filter thickness is 1.8mm so the back focus to be added is 1.8/3 = 0.6 mm... And that needs to be added to the total bacfocus... Is this necessary?
@GalacticHunter
3 жыл бұрын
Yes that rule is correct, but I usually just give it a quick try without changing the backfocus and remove a spacer ring if I see it is needed
@whatmattersmost6725
3 жыл бұрын
Thank you but those ext tubes are not M54 but M48 and M42 are the most 2 common size for ZWO and QHY. Great work as HATE the Back Focus issues and don't forget is say a Flattener/Reducer says it's 55mm of back focus, it may not be 55mm, maybe 54mm or 56mm! It's a try and see to get it correct.
@paths1111
3 жыл бұрын
Actually they are M69 extensions because he is threading to a Stellarvue large field flattener. The QHY camera angle adjuster ring is M54 threaded - the first piece is a M54 to M69 adapter followed by Stellarvue M69 extension rings. I have a similar setup, but my drawtube is fitted with an M54 endcap, so I go M54 extensions all the way.
@calvinfarrow1720
3 жыл бұрын
I wound up cutting down an adapter. After buying several spacer rings
@Steve_The_Ignorant_Astronomer
3 жыл бұрын
Here is what I do not understand. I have a Explorer Scientific ED-80 and it came with 2 extension tubes and I am using a ASI 294mc pro . When I put it on the scope I could not get the back focus so I had to add another tube. SO are they figured into the back focus equation ? My camera came with 2 rings and spacers but I dont know what to do with them since I am using the extension tubes, but I have elongated stars at the edges
@GalacticHunter
3 жыл бұрын
Usually back focus is calculated between the camera sensor and the reducer/field flattener, so those extension tubes would count indeed.
@Steve_The_Ignorant_Astronomer
3 жыл бұрын
@@GalacticHunter Yea I dont have a flattner yet and I use I think 3 extensions camera is way back, was hoping for neaf this past year but that never happened thx for getting back
@Steve_The_Ignorant_Astronomer
3 жыл бұрын
@@GalacticHunter Oh and Have a goos xmas
@KnyghtErrant
3 жыл бұрын
@@Steve_The_Ignorant_Astronomer If you don't have a field flattener yet, that's likely the primary reason you are seeing elongated stars.
@goatsuukerhill
3 жыл бұрын
No, it sounded to me you said the “piftiner” connected to the back focus spacers. What is a piftiner?
@KnyghtErrant
3 жыл бұрын
Field flattener
@goatsuukerhill
3 жыл бұрын
@@KnyghtErrant ah, thank you
@mahed82
3 жыл бұрын
Can i use my old celestron Motorize EQ mount to get longest exposure with a DSLR ?
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