The Saxon203... some success...

[Aussie Dave]

For those that had read some of my topics on the Saxon 203, this is where I'm at.

I managed to image with the Nikon straight on the end of the focuser tube, no problems there, in fact it's now with just enough outward focus.

I tried some lunar shots this evening after the sun went down, dusk. I seem to be having difficulties getting that sharp focused image, same issues as when I first imaged with it. I wouldn't post images that I'm not happy with but it's some progress, I guess as I'm back imaging with it without barlows and diagonals.

Nikon D3100, ISO100, 1/800 sec. They are over processed with sharpening to try and get rid of the fuzzy exposures.These are far from full sized images, I had to reduce the sizes dramatically.

Single shot, sharpened at max twice in Paint

8 stax in RS6, tweaked wavelets and sharpened in Paint

The only thing I can think of now is that the scope it too heavy for the EQ5 and any wind and/or the camera shutter vibration is affecting all the shots. I take shots with the 10 second timer and at 1/800th of a second I should be getting clearer images than what I am.

One day I may get there with this scope.

[Pete Presland]

Pretty good shots I am sure you will get there in the end.

[Aussie Dave]

Thanks for the kind comment Pete and encouragement. All I can say about those 2 are... they are images...

I'm 70% sure it's shutter vibration, all the shots have a double image which is much lighter. All images have this to varying degrees, some worse than others. So I know it's not optics or the mirror.

I just need to work out where the weak link is, I may need to add another weight to balance it perfectly.

Should I be imaging on live view, would this help?

[xtreemchaos]

i think there both good images Dave, thay show nice detail and colour and tone. well done, have you tried a mosaic yet?.thanks for sharing charl.

[Aussie Dave]

Thanks Charl but I'm not happy with the Saxon for imaging, it's a shocker. I really want to like this scope and keep it for visual and imaging. It's really frustrating. Successful imaging with the Saxon I haven't achieved.

No I haven't tried a mosaic yet but I will eventually get around to it. For now I have too much to test and not enough decent nights to do it all in. Progression is slow.

I'll post a couple of full res shots soon unprocessed.

[Aussie Dave]

This is what I'm dealing with. You can see the double and multiple images best in the bottom right of the moon on the small craters. You will need to view them full size.

double image

From what I can tell, a quadruple image

[xtreemchaos]

yer mate i can see it now, just a thought but is your camara sitting true in the focuser, i got the same result when my camera was off earlier in the year heres a mosaic with the camera not true, from the top to the middle is showing slite doubling....the scope used is a sw 200p.

[happy-kat]

Whilst you know you have double image happening the image itself looks really promising for detail and interest.

Hope you crack the issue soon.

[ngwillym]

Just a few thoughts:-

i) its a 1200mm fl scope and your exposing @ 1/800 - isn't the usual rule of thumb to avoid camera shake to have the exposure shorter than 1/focal length?

ii) multiple images could be the result of mirror slap - anything between two and 4 images (mirror starts to move at beginning of exposure, mirror stops, mirror starts to mover at end of exposure and mirror stops)?

iii) what's the weight of all the kit you have on the EQ5 (assuming its on a EQ5 mount like the ones advertised on amazon?) or is it the dobson version? if the former - then the payload  'limit' for the EQ5 is ~ 9kg and possibly 1/2 that for decent imaging? - even at 1/800 there may be some image drift if the motors are under strain.

[Aussie Dave]

yer mate i can see it now, just a thought but is your camara sitting true in the focuser, i got the same result when my camera was off earlier in the year heres a mosaic with the camera not true, from the top to the middle is showing slite doubling....the scope used is a sw 200p.25-9-15. dayoon.jpg

Yep Charl, looks similar to what I'm getting. Your shot is like my better images with this scope. I haven't had a clear shot yet. Camera sits in the focuser tube correctly, I made sure of that. I'm only getting this problem with this scope.

Whilst you know you have double image happening the image itself looks really promising for detail and interest.

Hope you crack the issue soon.

Thanks Happy-Kat, I'll get there, I think.

Just a few thoughts:-

i) its a 1200mm fl scope and your exposing @ 1/800 - isn't the usual rule of thumb to avoid camera shake to have the exposure shorter than 1/focal length?

ii) multiple images could be the result of mirror slap - anything between two and 4 images (mirror starts to move at beginning of exposure, mirror stops, mirror starts to mover at end of exposure and mirror stops)?

iii) what's the weight of all the kit you have on the EQ5 (assuming its on a EQ5 mount like the ones advertised on amazon?) or is it the dobson version? if the former - then the payload  'limit' for the EQ5 is ~ 9kg and possibly 1/2 that for decent imaging? - even at 1/800 there may be some image drift if the motors are under strain.

ngwillym it's a mixture of issues really with some of them you've mentioned.

fl is 2500mm which I don't think is helping, f/12.5. Mirror slap it could be but It's sold with a one speed Crayford style focuser, I'm not sure it has a moving primary mirror like the usual Cassegrains. Not much info out there on them, the ones I have seen all have the Crayford style focuser back, imaging that night at about 70 degrees. Some info below

http://www.kiwibinoculars.co.nz/shop/saxon-20325-eq5-maksutov-cassegrain/

it states no mirror shift so the primary mirror must be fixed.

The tripod/mount is a Skywatcher EQ5 with no motors, only slow motion knobs. You are correct in what you say though, too much weight for the mount with the scope being just under 14 kg.

When I first bought it I tried imaging with it on my Skywatcher EQ6 Pro with similar results in photos, perhaps not as bad as what Ive shown here in this thread. I don't think the EQ6 Pro is up for the job either.

All I can think of now is giving the SW EQ6 Pro another go, balance it correctly,  bump up to ISO200 and bump up shutter speed slightly each time and compare results. If that doesn't help then I don't know what to do. I'm now thinking pier !??

[happy-kat]

Don't extend the tripod legs keeping them short should help stability but not you crawling on the ground but in the chase for perfection...

[Cornelius Varley]

Is the Saxon 203 the 8" mak ? If so you will need to let it cool down for a long time to allow the optics to reach ambient temperature. Also if the camera has a video mode (I think the N3100 has) it might be better to shoot in video mode rather than a single or a small number of still images and then convert the movie file, using PIPP, into a format that Registax or one of the other stacking programmes can handle.

[ngwillym]

@Dave, sorry - when i was talking about mirror slap - I was referring to the mirror/prism in the camera, not the scope?

[ngwillym]

And another thought- usually planetary/lunar photography is done by taking lots of short exposures (100s or even 1000s) - usually in the form of video rather than individual still frames  and then stacking them - does the Nikon have a video capability?

[Aussie Dave]

Don't extend the tripod legs keeping them short should help stability but not you crawling on the ground but in the chase for perfection...

I've never had any of the legs extended Happy-Kat apart from the wobbly creaky wooden legs on the old Tasco which is part of it's charm. I'm often crouched down near the floor in most of my sessions, which is no good for my neck.

Is the Saxon 203 the 8" mak ? If so you will need to let it cool down for a long time to allow the optics to reach ambient temperature. Also if the camera has a video mode (I think the N3100 has) it might be better to shoot in video mode rather than a single or a small number of still images and then convert the movie file, using PIPP, into a format that Registax or one of the other stacking programmes can handle.

Yeah it's the Mak Pete. In a previous topic about this scope and problem images this was mentioned by other members. The temperature would have only been a few degrees cooler outside. I'm not sure it would result in multiple images, 2's and 4's, don't quote me on that though. I will try video, I've been saying that for a while now. I'll let it cool down for an hour at least next time, longer if the temperature differences are extreme.

@Dave, sorry - when i was talking about mirror slap - I was referring to the mirror/prism in the camera, not the scope?

Nah you're right mate, I was thinking of mirror flop in the scope. It could well be mirror vibration when it flips up and then back down from the top. There would be more vibration from the mirror than the shutter. You may have something there.

And another thought- usually planetary/lunar photography is done by taking lots of short exposures (100s or even 1000s) - usually in the form of video rather than individual still frames  and then stacking them - does the Nikon have a video capability?

Will try video next session.

[Aussie Dave]

So this is the list.

Let the scope cool down and avoid the temptation to image within at least 1 hour, try the EQ6 Pro, tripod legs up, balance it correctly with an extra balance weight, make sure everything is seated correctly and all screws tightened up, tighten the focus lock screw. try video and and also test on live view with the mirror up for single shots, test ISO and shutter speeds.

Strewth...Did I miss anything?

[happy-kat]

I don't get focus issues on Moon with mirror slap so I suspect mount is not rock steady which you already suspect.