First Light with new ASI585MC Pro.: Page 17

First Light with new ASI585MC Pro.

w7ay

Kevin_A Yes, I might just get one or two of those adjusters as this shimming business is getting to be a pain!

Won't work with camera lenses of course -- those adapters don't even have 1mm spare backfocus, much less 18mm :-).

But for the large scopes, they are a godsend.

BTW, I still couldn't test out the ASI678MM for guiding. The camera went all the way (by surface transportation) from southern California to Texas before they discovered it was travelling the wrong way. It then went back to southern California (!), and then to southern Oregon. It is finally at the main post office in Portland, and I may or may not get it tomorrow, it sometimes takes more than a day to move the 5 miles from there to my post office (if you are not aware, the US Postal System is run and staffed by idiots). But, there are no clear skies in sight until perhaps next Wednesday. I want to see if I can push the RST135e consistently to 0.25" by going near-IR guiding :-) :-). Right now, I can get it to be consistently below 0.4"; hovering around 0.35" most of the time.

Chen

Kevin_A

w7ay with Nikon lenses the is 46.5mm of backfocus so minus 17.5mm gives me 29mm to work with. I would have to use a M48 Rokinon adapter replacement ring. On my 533 and 183 cameras I could screw in a 1.25” filter into the front face of the camera. I would not need the Nikon filter adapter then… so I would have 29mm to fill. So… the askar is 18mm and that leaves me needing a 11mm spacer. Oh darn, that adapter is M54…. Drat!

w7ay

Kevin_A Oh darn, that adapter is M54…. Drat!

The Blue Fireball (Agena house brand; why these guys all hide their house branding is mysterious. Like supermakets and Home Depot (Ryobi) with their house brands) M54 adapters are what you want. I have a couple of their 4mm-9mm sets and some long ones, like 10mm, 15mm, 20mm, etc.

https://agenaastro.com/blue-fireball-m54-thread-spacer-set-3.html
https://agenaastro.com/blue-fireball-m54x0-75-spacer-ring-with-10mm-extension.html
https://agenaastro.com/blue-fireball-m54x0-75-spacer-ring-with-20mm-extension.html

For a house brand, they are surprisingly good (does not bind like the junk you get from ZWO). IMHO, just a half step below PreciseParts (also never freeze up on me). The good stuff like the Takahashi adapters are tight but don't bind.

No 2" filter threads in the Blue Fireball spacers. I think they want the clear opening (about 50mm) to be as wide as they could make it to reduce vignetting instead.

I also like the Blue Fireball shims (much finer steps than Baaders, and wide)

https://agenaastro.com/blue-fireball-9-pc-fine-tuning-spacer-ring-set-for-m54-threads-0-1-to-1-0-mm-s-set9.html

They have M42 and M48 sets too, but I have sometime ago standardize on M54. Eventually, as sensors become larger, we will all be using M68 :-).

Another thing Blue Fireball is good for is their metal M42, M48 and M54 endcaps. Both male and female. Pretty much as good (and a bit more refined, IMHO) than the Baader metal endcaps, and much cheaper in the Americas.

You won't be able to find Blue Fireball (including their pretty good camera angle adjuster) in the frozen north, since it is an Agena thing.

Chen

w7ay

Kevin_A

OK, I removed all the plastic parts at the back of the Samyang 135, and got to this, mostly metal, and couldn't remove further (even removed the 0.9mm hex with a spring). Everything appears to be bolted on tightly, but I don't know by what. Any idea how do I get to the iris from here?

I can see the iris, just couldn't get to it. (By the way, where exactly does that little ball that creates the aperture click stops go? By the time I have everything on my mat, the ball was just sitting there :-). Not that it matters since my plan is not to even use the aperture iris, and I have been using my leses wide open, with an externall aperture mask anyway.

Chen

w7ay

Kevin_A

Ah, I see two hex (I think) grub screws. But my 0.9mm hex wrench is too small, and a 1.3mm wrench does not work either. I need to order some assorted small hex wrenches.

Do you have the prcise size for those two screws, and are they wa=hat are kwwping me from reaching the iris?

Chen

Kevin_A

w7ay I think you will need to use the lens spanner down by the glass. I think the ball will be part of the parts you took off.

Kevin_A

w7ay I have 0.9, 1.0, 1.5mm hex wrenches but I do not know what sizes they are as most of the parts on mine were tiny Philips screws.

Kevin_A

w7ay a picture is worth a thousand words! Haha

w7ay

Kevin_A

OK., these are the two grub screw that I found... do I need to remove them? Seems to have some Loctite or something smeared over them.

I did find my set of small German metric wrenches... 2, 1.5, 1.3, 0.9, 0.7.. 1.3mm appears to be the right one. But with the Loctite, it means they don't want you to fool with them?

I think the ball will be part of the parts you took off.

Yeah, I found the ball, but which hole is it supposed to go into? :-)

I think you will need to use the lens spanner down by the glass.

Hmm, that won't allow me to remove the iris and replace with a milled part, though, does it? I need to be able to remove the iris completely.

Interstingly, there is an aperture stop somewhere that is fully circular, when you open the lens up completely to f/2.

Chen

w7ay

Kevin_A

Wow, how may turns with a lens spanner does it take to remove the glass anyway? I am at some 10 turns and the things is still in there.

The Neewer protractor type lens spanner is great, by the way.

Chen

Kevin_A

w7ay I would check that they do not use some imperial sizes along with metric… heck they might even use some weird screws too. Try an imperial size allen key when in doubt.

Kevin_A

w7ay maybe you have to remove a lens group before you get to the iris assembly.

w7ay

Kevin_A Try an imperial size allen key when in doubt.

Heck, I don't have many imperial wrenches anymore. 1/16", 1/4", 3/8". I have just one plastic box (about 1/4 cubic ft) of imperial bolts for 5/16", 1/4" and 3/8", while the same size box is barely large enough to hold my different M6 bolts. Between button heads and socket heads, and different lengths, you really need to stock up with M4 and M6 nowadays.

Chen

w7ay

Kevin_A maybe you have to remove a lens group before you get to the iris assembly.

I thought you had gotten to remove the iris completely? Do you remember what you had to remove?

The glass elements are still in there. Time for lunch. This thing can wait for a different day when I am in better mood. Go work on the Sigma 40 base plate first.

Chen

Kevin_A

w7ay I never got to my iris as mine has electronics and that adds another layer of complexity. Some of the Samyang/Rokinons have to have the outer barrels removed before you get to the isis, so the red ring and barrels may need to be removed first. So many variations. Look on YouTube under Rokinon disassembly as some require the outer barrel to get at an inner sleeve and some you just keep pulling out lens sets.

Kevin_A

w7ay check on YouTube as I think you might have to remove the focus barrel to remove the rear barrel.

w7ay

Kevin_A I never got to my iris as mine has electronics and that adds another layer of complexity.

Ouch, I thought you said you got to the iris.

OK, this project is definitely in the backburner now; perhaps buried for good. I will try to put things back to as normal as I can, and see if I can still get a working lens, without the aperture click stops (still have no idea where that ball goes into).

I don't like redneck engineering; working with no documentation. Life is too short for that.

Started to work on the Sigma 40 already. I am just going to modify the base plate of the Rokinon, seen here with a 1:1 printout and the Sigma to measure where to move some of the holes, and to figure out if I have the right belts in my stockpile. Perhaps send the design out before the next workweek for the web machine shop to work on it.

Speaking of belts, it really helps using 10mm belts instead of the 6mm astro hobbyists seem to like to use. Everything feels more solid. Well, that extra bearing to hold the EAF shaft definitely does not hurt either.

That Blue Fireball CAA that you see in the photo above, really helps in this case, belt or no belt. That tripod ring does not allow the lens to be rotated.

I am still trying to get used to the Nikon's left-handed bayonet! I keep tightening the bayonet when trying to remove the lens, and wonder why the bayonet does not even budge :-) :-).

I am still on the look out for the Sigma 40 with an EF mount. I don't think a new one exists on this planet anymore.

Chen

w7ay

Kevin_A

Ah, the ball goes into the spring, that I orignally thought was a 0.9mm hex grub screw.

Reversing the disassemby process now :-).

Chen

Kevin_A

w7ay there is a dedicated detent for the ball.

Kevin_A

w7ay yes, the reverse bayonet still on Nikon lenses still confuses me everytime… still!

Kevin_A

w7ay

https://youtu.be/pn02mk_M8Es?si=R0M-4Cgw14tOJoPs

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