22 replies to this topic

[Ittaku]

Spent an hour collimating again, have blisters on my finger this morning since my scope has the metal topped Bob's knobs collimation screws unique for the M16" which don't pop off (no other screws are exactly the right size so don't bother telling me replace them with hex screws.)

 

Good seeing 7/10.

 

Shown at 140%, moon brighter than captured.

 

 

 

IR642 bandpass shown at capture size

 

 

 

IR850 longpass shown at 65% scale

[MarMax]

Is there a wing-nut style screw that would work with the 16"?

 

This is what I use on the C11 and it's much better than the Bob's knobs (blisters on the fingers) style.

 

[dcaponeii]

Is there a wing-nut style screw that would work with the 16"?

 

This is what I use on the C11 and it's much better than the Bob's knobs (blisters on the fingers) style.

 

C11_CollimationScrew.jpg

He TOLD you NOT to tell him about getting different screws!!!  hehehe

 

Con - The effort was worth it.  Next time wear gloves.
 

[Ittaku]

Is there a wing-nut style screw that would work with the 16"?

 

This is what I use on the C11 and it's much better than the Bob's knobs (blisters on the fingers) style.

There might be, however I've been through the process of purchasing what is meant to be exactly the right size for this scope, only to have one screw come loose whilst tightening it on multiple occasions. When one screw comes loose on this scope, I have to remove the corrector plate; not fun in the dark during precious imaging time to then have to collimate completely from scratch as well.

[MarMax]

You must have the older three screw style.

 

I saw your post asking about the thread specification. Did you find out the specs?

 

Even though comparing the C11 to your 16 is like comparing a 10M boat to a 20M boat, I had to ask because I feel your pain.

 

[dcaponeii]

There might be, however I've been through the process of purchasing what is meant to be exactly the right size for this scope, only to have one screw come loose whilst tightening it on multiple occasions. When one screw comes loose on this scope, I have to remove the corrector plate; not fun in the dark during precious imaging time to then have to collimate completely from scratch as well.

Is it that the threads on the secondary holder are partly stripped letting the screw loosen again if you tighten too much?  I've had that happen to me with stainless fittings and can be worse with aluminum cause it's lower strength.  One of the female threads in the holder gets crossed and you'll be tightening the screw and then all of a sudden the screw can cross thread and essentially jump back half a thread and is loose again.

[Kokatha man]

I'd like to see you raise the black-point slightly and compensate with the middle slider in levels to get rid of that annoying abrupt background change around Saturn's periphery Con but apart from that a very nice outcome..!   

 

A nice, solid Cassini Division all round the planet's front, which is isn't too easy to get these days...

[Ittaku]

I'd like to see you raise the black-point slightly and compensate with the middle slider in levels to get rid of that annoying abrupt background change around Saturn's periphery Con but apart from that a very nice outcome..!

A nice, solid Cassini Division all round the planet's front, which is isn't too easy to get these days...

Thanks. I don't adjust black point or gamma at all. Won't adjusting the black point increase the contrast more, or am I misunderstanding what you're suggesting?

[Ittaku]

Is it that the threads on the secondary holder are partly stripped letting the screw loosen again if you tighten too much? I've had that happen to me with stainless fittings and can be worse with aluminum cause it's lower strength. One of the female threads in the holder gets crossed and you'll be tightening the screw and then all of a sudden the screw can cross thread and essentially jump back half a thread and is loose again.

No, it was simply 1mm too short, with perhaps just the last bit stripped?

Edited by Ittaku, 22 September 2023 - 08:56 PM.

[Ittaku]

You must have the older three screw style.

I saw your post asking about the thread specification. Did you find out the specs?


Even though comparing the C11 to your 16 is like comparing a 10M boat to a 20M boat, I had to ask because I feel your pain.

Yes of course, it's a 30 year old scope. I did find the specs and ordered screws for it, only to find they're marginally shorter than Bob's, by perhaps 1mm.

[Kokatha man]

Thanks. I don't adjust black point or gamma at all. Won't adjusting the black point increase the contrast more, or am I misunderstanding what you're suggesting?

For some reason CN won't let me post the gif I made for you Con...it is only 121kb and 1188w x 671h so I have no idea why not except that CN sometimes acts strangely...will post later if it sorts itself out!

 

Tried reducing it to 80% of first full-size gif but still  no dice.....very strange because I can upload any other images...try applying levels of 0-1.09-255 and toggle the preview box on and off - you should see that gradient disappear but the planet's brightness etc will not change. (your contrast comment)

[MarMax]

Yes of course, it's a 30 year old scope. I did find the specs and ordered screws for it, only to find they're marginally shorter than Bob's, by perhaps 1mm.

If you want to try a wing-nut type screw just lmk the specs and I'll get them from McMaster-Carr and ship them to you. They have just about everything you can imagine.

[Ittaku]

If you want to try a wing-nut type screw just lmk the specs and I'll get them from McMaster-Carr and ship them to you. They have just about everything you can imagine.

Thanks for the offer. This is the issue - I ordered exactly according to the specs I could find, only to find the screws were fractionally shorter than Bob's knobs' ones. I don't know how to account for the "fudge factor" since I measured them with the micrometer to confirm.

[Ittaku]

For some reason CN won't let me post the gif I made for you Con...it is only 121kb and 1188w x 671h so I have no idea why not except that CN sometimes acts strangely...will post later if it sorts itself out!

 

Tried reducing it to 80% of first full-size gif but still  no dice.....very strange because I can upload any other images...try applying levels of 0-1.09-255 and toggle the preview box on and off - you should see that gradient disappear but the planet's brightness etc will not change. (your contrast comment)

You mean make the black not quite black? Like this? output levels 1-255

 

 

Or bring down black like this? Input levels 1-255

 

 

Or something else? I'm having trouble seeing any difference.

[MarMax]

Thanks for the offer. This is the issue - I ordered exactly according to the specs I could find, only to find the screws were fractionally shorter than Bob's knobs' ones. I don't know how to account for the "fudge factor" since I measured them with the micrometer to confirm.

Hardware is always a bit tricky, especially when every 0.5mm matters. I like having a washer on the wing-nut screw so I ordered the screws longer and added washers to get my desired length. Looking at the picture in the Astronomics link it should not matter if you had some washers for fine adjustment. And MC has a bazillion different washers so you can get any size and thickness imaginable.

 

The other thing I did with my wing-nut screws is carefully grind the ends smooth and put a slight chamfer on the edge. This way the ends don't dig into the aluminum secondary backing and are smooth when tightening and loosening. It's a bit more work but next time you have the scope apart you could helicoil the threads and then you dont have to worry about stripping ever again. It sounds like you have quite a bit of wear on those threads already. And since I have no idea what your secondary internals look like, my comments may be completely off.

[Ittaku]

Hardware is always a bit tricky, especially when every 0.5mm matters. I like having a washer on the wing-nut screw so I ordered the screws longer and added washers to get my desired length. Looking at the picture in the Astronomics link it should not matter if you had some washers for fine adjustment. And MC has a bazillion different washers so you can get any size and thickness imaginable.

 

The other thing I did with my wing-nut screws is carefully grind the ends smooth and put a slight chamfer on the edge. This way the ends don't dig into the aluminum secondary backing and are smooth when tightening and loosening. It's a bit more work but next time you have the scope apart you could helicoil the threads and then you dont have to worry about stripping ever again. It sounds like you have quite a bit of wear on those threads already. And since I have no idea what your secondary internals look like, my comments may be completely off.

I have zero hardware expertise, and what you describe sounds very elegant but uh beyond me. I'm all thumbs with craftsmanship work. I have a feeling that me dicking with it right now will only cause me further pain. Definitely a job for someone experienced to do instead, should I ever be forced to unwillingly take the corrector plate & secondary off again. Thanks.

Edited by Ittaku, 22 September 2023 - 11:02 PM.

[Ittaku]

And just to round things off for anyone still interested in collimation screw discussion, this is why the 1" long screws I bought kept slipping. My fault entirely I know. Anyway I'm not pulling apart the scope ever again if I can help it. You can also see the nice robust - yet finger shredding - sold metal head on Bob's.

 

Edited by Ittaku, 23 September 2023 - 12:38 AM.

[Ittaku]

He TOLD you NOT to tell him about getting different screws!!!  hehehe

 

Con - The effort was worth it.  Next time wear gloves.
 

Thanks a lot. Funnily enough I've destroyed a pair of gloves on these already.

[Kokatha man]

Apologies, I meant "14 - 1.09 - 255" 

[Ittaku]

Okay let's try again, I hope I've understood your instructions, I'm adjusting "output levels" in The Gimp since I don't have/use PS. Before and after:

 

[Space Cowboy]

Super Saturns. Well worth the blisters!

[Kokatha man]

Okay let's try again, I hope I've understood your instructions, I'm adjusting "output levels" in The Gimp since I don't have/use PS. Before and after:

 

Yep, that's it Con...still a bit of lighter "fuzz" on the upper right just off the disk but better imo. Gets rid of that ghostly circular feature just above and out from the L. ansa also.

 

On the matter of getting fingers sore from knurled collimating screws, take a leaf from my approach, perhaps with different materials because I used some large diameter shrink-wrap insulation from Jaycar - but this requires removing a screw to apply heat for shrinking it onto the knurled head.

 

You could also get a short length of some soft rubber tubing from Clarke Rubber or whoever in the appropriate diameter and stretch it onto the knurled knob - no more pain or soreness then...you can see how rough I made my home-made ones but they feel dandy to adjust. Not that this helped this morning - the defocused star was just a sparkling mess.

 

First pikky shows how rough my serrating was for the new ones shown next to the smaller, old version.

 

 

Second pikky with the "gentle on your fingers" covering. 

 

[Ittaku]

Thanks Darryl. I definitely see what you're talking about there. I do think the c ring is less well defined as a result of cleaning it up like that though. I'm looking into potential solutions to the finger ripping screws now so what you've shown is great food for thought.