215 replies to this topic

[markmanner]

Today my wife and I improved the insulation again so that the tape is no longer visible.

 But at the moment it seems to be working so well.

 Furthermore, the counterweight rod is still neatly modified.

 The fan also gets a filter housing and a 90 degree viewfinder is attached.

Great news. As an owner of a 12" mak, I know the challenges of getting it tuned up, but it is worth it! It is hard to believe how much a difference reflectix and collimation make.  Also, having a sturdy mount (and back to put it on it).

Best,
Mark

[StefanBemmerl]

Hello! I'll answer all of them in one text... I can't remove the rope guard, it weighs 5 kg and would have to be completely rebalanced every time. My new problem is that I have a remote observatory and have often put different telescopes on the mount to take photos. However, you can't just take this heavy monster down again, let's see how I solve it... My wife and I had to take it down again because it was 180 degrees upside down and it went towards the ground in the home position. When we turned it we heard a rattling and after checking it with the Ocal it was properly misaligned when we took it down. What also worries me a lot - it can easily wobble. As if the rail was no longer completely tight. But this is screwed on from the inside of the tube with normal small cross screws, I don't like that at all, you can't get to it! Otherwise I'm waiting for clear skies again and a Televue 55mm and Televue 18.2 Delite. As a next test I would like to try which binary stars can be separated using this. Of course I will report again, of course only if requested. Kind regards, Steve

[markmanner]

Hello! I'll answer all of them in one text... I can't remove the rope guard, it weighs 5 kg and would have to be completely rebalanced every time. My new problem is that I have a remote observatory and have often put different telescopes on the mount to take photos. However, you can't just take this heavy monster down again, let's see how I solve it... My wife and I had to take it down again because it was 180 degrees upside down and it went towards the ground in the home position. When we turned it we heard a rattling and after checking it with the Ocal it was properly misaligned when we took it down. What also worries me a lot - it can easily wobble. As if the rail was no longer completely tight. But this is screwed on from the inside of the tube with normal small cross screws, I don't like that at all, you can't get to it! Otherwise I'm waiting for clear skies again and a Televue 55mm and Televue 18.2 Delite. As a next test I would like to try which binary stars can be separated using this. Of course I will report again, of course only if requested. Kind regards, Steve

Hi Steve, my somewhat monster sized 12" mak has rings attached to a D dovetail, which seems to be appropriate for that sized scope. Is your mak mounted on an attached dovetail? Is that the rail you mention is a bit loose?  My 7" Intes Alter M715 has a mounting plate screwed into the OTA, but that seems ok for that size telescope. 

[StefanBemmerl]

Hello, that's right, here too a mounting plate is screwed on from the inside, see picture, these screws no longer seem to be completely tight. When I look inside I can see that only normal small cross screws were used here. That's certainly how it was done, but they're no longer completely secure and you can easily wobble them. How are you ever supposed to get there?...

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[markmanner]

Hello, that's right, here too a mounting plate is screwed on from the inside, see picture, these screws no longer seem to be completely tight. When I look inside I can see that only normal small cross screws were used here. That's certainly how it was done, but they're no longer completely secure and you can easily wobble them. How are you ever supposed to get there?...

Hi, the only way is to remove the meniscus cell assembly or rear primary mirror cell. I've done that with my 12" TEC mak-cass, but it does require some work. My worry would be that even if you can access those screws, that they won't tighten properly.  Would you consider buying some rings? That would certainly be more stable and allow for rotation of the OTA if you want to, and attach a top plate, etc.  Have fun!

[NevelP]

With my Intes MK91, I was surprised how easy it was to remove the meniscus, install flocking material in the tube and then reinstall the meniscus. It only took unscrewing a few clamping bolts and then lifting the meniscus out, after marking with small stickers the original position it was in. I’m not sure if that’s the same with the 1212” from IM, but it’s worth a look.

As markmanner said, I would also consider using tube rings, although a firmly tightened dovetail directly on the tube should also work (doesn’t a C14 have such a thing as well?). But there must be sufficient bolts that hold really firm as well.

[markmanner]

With my Intes MK91, I was surprised how easy it was to remove the meniscus, install flocking material in the tube and then reinstall the meniscus. It only took unscrewing a few clamping bolts and then lifting the meniscus out, after marking with small stickers the original position it was in. I’m not sure if that’s the same with the 1212” from IM, but it’s worth a look.

As markmanner said, I would also consider using tube rings, although a firmly tightened dovetail directly on the tube should also work (doesn’t a C14 have such a thing as well?). But there must be sufficient bolts that hold really firm as well.

Hi, the C14s have a dovetail on the bottom, but it is attached at the front and rear cells, not the tube itself.  The AP 10" mak-cass first run have dovetails attached to the tube. That Mak is considerably lighter than the 12" Intes though, and the attachments are really robust. Pic attached.

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[thebonz]

Adding rings will make it much easier to mount but will also add some weight and also push out the center of gravity requiring more counterweight to balance the system. As mentioned earlier, the eq8 is already near its limits

[luxo II]

Adding rings will make it much easier to mount but will also add some weight and also push out the center of gravity requiring more counterweight to balance the system. As mentioned earlier, the eq8 is already near its limits

Not so sure about that.

 

Mark - I would expect a dovetail bar that long will twist visibly under the weight of your 12" - the one under my 10" did, when mounted like that.

 

I'm pretty sure Stefans one is an Intes (not an Intes-Micro) with the machined aluminium tube (yes they did turn them !) and the textured paint, exactly like my MK66 and the MK91 I had (now with Alex - which was built by Intes, though labelled as Santel).  

 

On both the MK66 and MK91 the Russians simply tapped the holes in the aluminium and secured a base plate using a half dozen bolts - there were no nuts on the inside. To that, attach a dovetail of your choice.

 

I would describe it as flimsy - while it is OK to mount a 6" like that (my MK66) IMHO you could see in the MK91 that the OTA distorts in some positions around the sky.

 

I would expect Stefans is the same.

 

The best arrangement I've seen - bar none - are the rings Matthias Wirth made for my 10". They are quite light (unlike the hideous cast monsters from Parallax) and the OTA sits quite snug on the dovetail under - there is no height penalty.

 

The other thing is the dovetail. Originally I had a long Losmandy dovetail with the rings as far apart as possible. With the dec axis horizontal, looking along the dovetail the ends were visibly twisting, which was a bit of a surprise.

 

Subsequently I replaced that with shorter dovetails very close to the length of the dovetail clamp on my mount, the point being that these transfer the load from the rings to the jaws of the clamp without any length in between that can twist.  And guess what - the cone error vanished and the whole assembly is very rigid. 

 

In Stefans position I'd suggest measuring the diameter of the OTA carefully, add 2-3mm to be sure (you can fill that with felt anyway) and then ask Markus to get in touch with Matthias Wirth and ask if he could make a set of rings like the ones he supplied for my 10".

 

Stefan if you want to go this route I'll provide details of the purchase from APM so Markus will know exactly which scope this is, and make sure you ask for 6mm drilled and tapped holes spaced to suit the dovetail.

 

The dovetail I use is https://www.sidereal...dovetail-200mm/... and the hole spacings for the rings were 55mm.

 

Lastly the rings make it very easy to piggyback another scope (eg small refractor) for wide field imaging.

Edited by luxo II, 20 February 2024 - 08:48 PM.

[markmanner]

"Mark - I would expect a dovetail bar that long will twist visibly under the weight of your 12" - the one under my 10" did, when mounted like that."

 

Luxo, that is the 10" AP mak, not the 12" TEC. There are rings on the 12".  The AP10" definitely doesn't twist on that dovetail. It weighs 33 lbs, a few more with the Dew cap and instruments, less than 1/2 of the TEC 12". 

Edited by markmanner, 20 February 2024 - 08:56 PM.

[luxo II]

Mine weighs about the same - 15kg and the bar was a Losmandy one - even more massive than yours, IMHO.

 

When its on the mount one night, with the dec axis horizontal and the scope horizontal (ie point north and zero degrees elevation) then look carefully along the length of the dovetail comparing the ends vs the clamp.

 

You might be surprised at what you see.

 

Stefans scope is more like 30+ kg, and its centre of gravity is further from the dovetail.

Edited by luxo II, 20 February 2024 - 09:03 PM.

[markmanner]

Mine weighs about the same - 15kgmand the bar was a Losmandy one - even more massive than yours, IMHO.

 

Look along the length of the dovetail comparing the ends vs the clamp. You might be surprised.

No doubt I'm capable of a lot of different surprises, but the rigidity of that particular scope isn't likely to be one of them .

[StefanBemmerl]

The ring thing would of course be a great solution. But my Intes with OAZ and rail already weighs 45 kg! The EQ8 is absolutely at its limit.

[NevelP]

Stefan if you want to go this route I'll provide details of the purchase from APM so Markus will know exactly which scope this is, and make sure you ask for 6mm drilled and tapped holes spaced to suit the dovetail.

Luxo, would you share those details with me also via PM? My MK91 has no rings, only a dovetail attached to the tube with just a few screws. I had not thought about the possibility of bending the tube.

[NevelP]

The ring thing would of course be a great solution. But my Intes with OAZ and rail already weighs 45 kg! The EQ8 is absolutely at its limit.

The observatory in Passau from your country sells its AP1200 at the moment for a fraction of its worth. That mount would be better for your scope. 

[R Botero]

Indeed, for a 12" telescope, particularly a long focal length Mak you need a bigger mount and rings. I had an EQ8 once for my 10" f/20 TEC and it was not stable enough, even for visual only.
Roberto

[luxo II]

That’s interesting Roberto, I was wondering about an EQ8 for mine before I bought the CQ350, which does OK for a portable setup.

But yes I’d love an AP mount …

Edited by luxo II, 21 February 2024 - 04:32 AM.

[Kitfox]

Stephan, contact Markus before you pull the cell or meniscus off; I would bet he has done one or the other on this precious scope and can give you guidance.

 

I agree on the EQ 8, although on your solid pier it may be up to the task for visual.  I love my AP 1200; one of these would be great.

 

My 7" STF has rings, I would not like anything attached solely to a small area of the tube, unless the tube is heavy and turned or the dovetail is attached directly to  substantial internal baffles.

Edited by Kitfox, 21 February 2024 - 05:32 PM.

[StefanBemmerl]

Good morning from the Bavarian Forest. I think that the way the rail is designed is ok, it was certainly made that way by people who had an idea. The previous owner also had it on there and also on an EQ8. But as mentioned, the screws are probably no longer completely tight, I'll take a closer look at it again at the weekend. I would never remove the lens because I would be too afraid of something breaking. What I also noticed is that the three adjustment screws are almost loose. Should I tighten them and then adjust them again? The EQ8 is certainly not ideal for this but it is still possible. What I would like to do would be to replace the dew cap (it weighs 5 kg!) with a 3D printed one. However, because of the balance, I would have to push the telescope much further forward and here I no longer have any space and in certain positions I already hit the wall. I'll take a closer look at it again and now I'm really looking forward to another observation!

[luxo II]

Stefan if you're referring to the screws retaining  the corrector in its cell, or those for adjusting the secondary, they are not supposed to be tight, just finger-firm, that's all.

 

If you consider removing the corrector, remember tis is 40mm thick and its a massive heavy piece of glass. Make sure you have a work area prepared such that it cannot go far if the unthinkable happens, and it has something soft and clean to land on (a pile of towels), 

 

Likewise the primary alignment screws should only be finger firm, not tight.

 

If you are worried any might work those the usual trick is to apply a dab of nail polish with a Q-tip over the head. It is sufficient, yet easily scraped off later.

Edited by luxo II, 22 February 2024 - 02:28 AM.

[StefanBemmerl]

Thanks Luxo for the info! Do you mean a kind of screw lock so that the adjustment screws no longer move? Yes, you can easily turn these by hand, it's good to know that it fits that way.

[R Botero]

Stefan

 

The screws around the corrector (around the OTA) should be tight.  If any part of your scope is moving freely, it needs to be tightened.  Finger tight for optics, tighter for mechanical elements.  You have one very big telescope - APM should be on the phone to you telling you what to expect.

 

Removing the corrector is not that difficult.  You just need to be careful and have (a clean) space to work on.  I take off the corrector from my 10" TEC regularly for cleaning and have taken the scope apart at least once:

 

https://www.cloudyni...ing/?p=12799445

 

 

Test if you need the dew shield now that you have added insulation.  If dew does start to form, get that 3D printed one.  If not, you can live without it - as I do here in London which will be as humid if not more than the Bavarian Forest.

 

Roberto

Edited by R Botero, 22 February 2024 - 04:16 AM.

[StefanBemmerl]

Hi Roberto, uh that looks like open heart surgery - a cleaning probably wouldn't go amiss for me either, but probably not absolutely necessary. I probably wouldn't dare. I think that without a dew cap the lens will fog up. I think I'll actually print one because this one is definitely lighter and I'll make it shorter otherwise I'll hit my wall. I also don't think these panels in the dew cap really have any proven use...

[luxo II]

Stefan it is imho important to give the glass - and the inside of the OTA - a gentle wash every couple of years to make sure they do not grow fungus, especially if you have a humid climate. I flush the outer surface of the corrector of my 10” about twice a year with distilled water mainly to take the dust off, but also remove any spores, and also put it out in full sun on a hot day as UV kills the spores. 

 

Fungus doesn’t matter on a scope easily replaced (Celestron) but it does with these scopes.

 

NB I’ve just come from a star party where a local fellow has a C8 barely a year old and it already has two patches of fungus on the corrector the size of a fingernail. It had been stored with no real thought in a damp location.

 

The russian coatings were good and can last several decades if not neglected. 

Edited by luxo II, 22 February 2024 - 07:16 AM.

[StefanBemmerl]

I think mine has never been cleaned. It is about 15 years old. I recently noticed that there was fog on the inside, which went away quickly when I turned on the fan. I'm currently attaching the dust filter to the fan. Does it perhaps make sense to leave the fan running permanently to keep the interior dry and ventilated? I also have a central ventilation system in my house; in winter we usually only have humidity well below 30 percent and we even have a humidifier in the house. Maybe the principle works similarly then no fungi should form and of course with a pollen filter to avoid dust inside?