119 replies to this topic

[YAOG]

Don't like the clamshell clamps, not just because they look ugly to me, but because they only use 1 bolt. So an attractive expensive OTA is IMO inadequately secured in an unattractive fixing - put heavy accessories on the OTA, the single bolt and single tube holder has more load to bear. 

 

The photos above with 2 tube rings, I consider minimum safety. My own 2 Taks, I use 3 rings on a Losmandy D bar, which is also easier to slide in its clamp than loosening rings bolts and moving the OTA on its own.

 

The GEM in DD's vlog is cool. And I am a book & atlas fan, Burnhams still rocks!

Putting appearance aside your fear of using a single bolt fastener for the clamshell is poorly informed. I don't recall the size of the fastener in the clamshell but even a very small M4 fastener of the cheapest class 4.6 material will need at least 58,000 PSI before yielding, not failing! I'm pretty sure Takahashi would use at least an M6 class 10.8 fastener for appearance and ease of handling, the fastener cost difference is trivial. 

 

In fact it is not possible to load the tube holder with enough weight to even minimally begin to stress a tiny M4 fastener let alone the likely much larger size Tak actually uses in their clamshells. 

 

Functionally the single fastener tubeholder adjustment when used on a Takahashi mount as designed, is much easier to use when balancing the optical tube in the tubeholder. If a Takahashi clamshell is used on a Losmandy dovetail IMO it's easier to slide the dovetail to achieve fine balance which is why I closely balance the optical tube in the rings and use longer dovetails. 

 

Chip

[Daniel Mounsey]

In my opinion, the clam ring is a brilliant mechanical design. I've used all the clam rings since day one with Taks and they've been wonderful, safe and very practical to use in the field. 

[RAKing]

Putting appearance aside your fear of using a single bolt fastener for the clamshell is poorly informed. I don't recall the size of the fastener in the clamshell but even a very small M4 fastener of the cheapest class 4.6 material will need at least 58,000 PSI before yielding, not failing! I'm pretty sure Takahashi would use at least an M6 class 10.8 fastener for appearance and ease of handling, the fastener cost difference is trivial. 

 

In fact it is not possible to load the tube holder with enough weight to even minimally begin to stress a tiny M4 fastener let alone the likely much larger size Tak actually uses in their clamshells. 

 

Functionally the single fastener tubeholder adjustment when used on a Takahashi mount as designed, is much easier to use when balancing the optical tube in the tubeholder. If a Takahashi clamshell is used on a Losmandy dovetail IMO it's easier to slide the dovetail to achieve fine balance which is why I closely balance the optical tube in the rings and use longer dovetails. 

 

Chip

 

Agreed.  IIRC, the bolts on my Tak clamshells were M8 -  which is more than enough strength for our needs.  I have always tried to explain to people that a single 1/4x20 bolt has plenty of grip and sheer strength for our static loads.  So even if they wanted to do pull ups with their OTA, the bolts would hold.

 

The Tak clamshells work quite well, but I just happen to prefer a pair of scope rings so I can easily mount a handle on top.  Using three rings to hold your scope is a waste of money, IMHO.

 

Cheers,

 

Ron

[Ihtegla Sar]

Agreed. People used to use 1/4 inch bolts for rock climbing. Now they have mostly upgraded to 3/8 inch for an added margin of safety, since there have been case of a 1/4 inch bolt shearing when someone took a particularly large fall on one. But I have climbed on 1/4 inch bolts before and trsted them by putting my weight on them. The stresses involved with a 170 pound climber bouncing their weight on a quarter inch bolt are incredibly higher than any telescope that can be easily lifted by one person. I wouldn't worry at all about a 1/4 inch bolt failing in normal operation of a telescope steel is incredibly strong.

My only concern about attaching a scope with a single bolt is that it might work its way loose. But the Tak clamshell attaches to the dovetail with two bolts and if the single clamshell bolt were to come a little loose, the telescope would start to slip in the mount, but that little slippage would let you would know something was amiss long before there was any risk of the scope falling. It's a really well made and secure clamshell.

[Steve Allison]

Interesting post about rock climbing hardware.

 

By the way, bolts for connecting rod caps in gasoline engines, which aren't very big, can withstand forces of 220,000 pounds per square inch or more.

[25585]

Maybe I'm in the minority, but I love the Tak clamshell. I use it mostly for visual. I have used the new Tak clamshell GT-40 for AP aswell, works great.

 

I watched the whole 45 min plus video of Daniel Mounsey on Youtube about the Tak FC-100 and EM-11. And he mentioned that as the Tak clamshell, as it has one bolt, it's much easier to adjust the ota position when observing instead of adjusting two bolts. I think that's a great point.

Too much risk. Like a car with one brake only working. 

[25585]

Agreed. People used to use 1/4 inch bolts for rock climbing. Now they have mostly upgraded to 3/8 inch for an added margin of safety, since there have been case of a 1/4 inch bolt shearing when someone took a particularly large fall on one. But I have climbed on 1/4 inch bolts before and trsted them by putting my weight on them. The stresses involved with a 170 pound climber bouncing their weight on a quarter inch bolt are incredibly higher than any telescope that can be easily lifted by one person. I wouldn't worry at all about a 1/4 inch bolt failing in normal operation of a telescope steel is incredibly strong.

My only concern about attaching a scope with a single bolt is that it might work its way loose. But the Tak clamshell attaches to the dovetail with two bolts and if the single clamshell bolt were to come a little loose, the telescope would start to slip in the mount, but that little slippage would let you would know something was amiss long before there was any risk of the scope falling. It's a really well made and secure clamshell.

Bolded, is where my concern is. I am a belt & braces guy. The more at risk, the more securing down I like. Then I can use with peace of mind.

 

But I use Tele Vue clamshells on my 3 TV fracs. The TV design has a captured non-opening shell top, but has a loosening bolt to allow enough slack for an OTA to be moved. And it looks attractive, unlike Takahashi's plumber's part.

 

But it is me & my money & my taste, a personal preference.

Edited by 25585, 09 July 2019 - 09:41 AM.

[John Huntley]

Rather than talk about clamps vs rings (I'm a fan of the clamp as well by the way) I think the new Tak FC100DZ might have some bearing on this thread comparing the merits of the DL, DF and DC

 

F/8.2 with a sliding dew sheild. Very nice indeed

[YAOG]

Rather than talk about clamps vs rings (I'm a fan of the clamp as well by the way) I think the new Tak FC100DZ might have some bearing on this thread comparing the merits of the DL, DF and DC

 

F/8.2 with a sliding dew sheild. Very nice indeed

Yes, this is a new item, so new JH finally posted something incorrect, the new DZ is actually f/8! JK JH!

[YAOG]

If you look at the curves and spot diagrams for the new Takahashi FC100DZ there is a distinct CA correction advantage for imaging. But interestingly spot sizes still look smaller for the longer f/9 DL when used with the same .66x flattener. 

 

But apropos to the subject header if you look at the charts for the faster f/7.4 DC/DF vs. the f/9 DL for visual use the DL looks better but the f/8 DZ edges out the DL. For imagers it seems the new FC100DZ should be a noticeable step up, at least on paper. How this works out in the real world remains to be seen but IMO nobody is going to buy a DF or DL with the DZ's price being only about $100 bump. 

 

 

Chip

Edited by YAOG, 09 July 2019 - 12:50 PM.

[John Huntley]

Yes, this is a new item, so new JH finally posted something incorrect, the new DZ is actually f/8! JK JH!

Oops !!! - quite right F/8 !!!

 

I agree re: the spot sizes when the .66x FR is employed - those are impressive.

[YAOG]

Bolded, is where my concern is. I am a belt & braces guy. The more at risk, the more securing down I like. Then I can use with peace of mind.

 

But I use Tele Vue clamshells on my 3 TV fracs. The TV design has a captured non-opening shell top, but has a loosening bolt to allow enough slack for an OTA to be moved. And it looks attractive, unlike Takahashi's plumber's part.

 

But it is me & my money & my taste, a personal preference.

Indeed it is your money regardless of how irrational or biased your preference is. A single fastener is a single fastener, there is no magic hand that is going to mysteriously loosen the locking knob when you're not looking. Unless you believe in the Easter Bunny or that Elvis is still alive this is not going to happen without operator intervention. 

 

Chip

Edited by YAOG, 09 July 2019 - 12:29 PM.

[YAOG]

Oops !!! - quite right F/8 !!!

 

I agree re: the spot sizes when the .66x FR is employed - those are impressive.

I might finally have to buy a Takahashi at retail, I missed out on the original issue DLs but maybe it was so I could buy one of these DZs?

 

Chip

[Ihtegla Sar]

There are also "lawyer lips" on the Tak clam shell, so even after the knob is unscrewed enough to rattle, the clam shell won't open until you loosen it a couple more turns and pull it up and over the lips, so there is really no danger of a scope falling out of the clam shell.  I only point this out for others who may read this and wonder about the security of the Tak clam shell.  Not trying to convince anyone to change their personal preference.  The clam shell does have a unique appearance.  Personally I find it quite fetching and the Tak blue looks nice with my white LX70 mount.  But beauty is in the eye of the beholder and everyone has different taste.  

Edited by Ihtegla Sar, 09 July 2019 - 12:11 PM.

[rerun]

Yes Steve Itotaly agree I like the TAK clam shell, too. For moving my FC100DF inside the clamp shell I just unscrew the knobs a few turns and it is easy and safe to move my scope, say on a german mount when I switch to another area in the sky. I only have to turn one knob there for I like the Tak clam shell very much.

 

Clear skies Markus 

[25585]

Indeed it is your money regardless of how irrational or biased your preference is. A single fastener is a single fastener, there is no magic hand that is going to mysteriously loosen the locking knob when you're not looking. Unless you believe in the Easter Bunny or that Elvis is still alive this is not going to happen without operator intervention. 

 

Chip

I tried the Tak clamp on my DL. With a heavy diagonal and eyepiece (AP Maxbright and Meade SWA 40mm 5000). 

 

An advantage of rings is that being 2 or more different fixings, they can be spaced out along an OTA for weight distribution, as a user deems necessary. Remember Tak gear is lightweight generally, so their single clamshell will be less strained using just Tak stuff.

 

 A DC is the lightest FC100. Takahashi may keep it for that reason. The DF and DL focuser will be put on the DZ I expect.

[Ihtegla Sar]

I have used the Tak clam shell with the ES 12mm 92 and liked the narrower grip of the clam shell vs spaced out tube rings because it let me slide the OTA further forward to achieve better balance with a heavy eyepiece, given the light weight of the doublet at the far end of the OTA.

[barbie]

I too prefer the clamshell for easier balancing.

[YAOG]

I tried the Tak clamp on my DL. With a heavy diagonal and eyepiece (AP Maxbright and Meade SWA 40mm 5000). 

 

An advantage of rings is that being 2 or more different fixings, they can be spaced out along an OTA for weight distribution, as a user deems necessary. Remember Tak gear is lightweight generally, so their single clamshell will be less strained using just Tak stuff.

 

 A DC is the lightest FC100. Takahashi may keep it for that reason. The DF and DL focuser will be put on the DZ I expect.

I'm sure the Maxbright and 2" grenade eyepiece balanced just fine with the DL's tube pushed forward a bit further in the clamshell like it does for everyone else.

 

Again with the mystical "strain" mumbo jumbo. The longer heavier Takahashi FC100DL specific clamshell could probably hold up a small car. No amount accessories you can stuff into the focuser or hang off the tube would cause the clamshell to fail before the optical tube collapsed. 

 

Where do these mysterious forces that can loosen clamping knobs and break clamshells come from? What hidden conspiracy is lurking in the shadows waiting to jump out and break your equipment?

 

Has anybody else seen these secret powers at work? Oompa Loompas? Little green men? I'm just saying, sounds nuts to me. 

 

Chip

[jay.i]

Does anyone other than me move the dovetail in the saddle instead of moving the scope in the rings/clamshell in order to balance the scope? I literally never move the scope in the rings, I use the dovetail for that... and most times I don't even need to move it, as my setups are back heavy, so I use moderate tension and the scope doesn't move when I swap eyepieces, yet I can move the scope as necessary without much force. I see no reason why you should move the scope inside the rings/clamshell.

[waso29]

pick your poison, or wait for $2850 fc100dz

Attached Thumbnails

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[Heywood]

pick your poison, or wait for $2850 fc100dz

 

Which website is that?  It looks like Anacortes, but I don't see such prices on the Anacortes website.

 

Oh, I see now.  Your pic is from two years ago.

 

Why post that pic now????

Edited by Heywood, 09 July 2019 - 06:11 PM.

[Tyson M]

I checked too, the prices are outdated from what appears to be Anacortes.

[John Huntley]

Does anyone other than me move the dovetail in the saddle instead of moving the scope in the rings/clamshell in order to balance the scope? I literally never move the scope in the rings, I use the dovetail for that... and most times I don't even need to move it, as my setups are back heavy, so I use moderate tension and the scope doesn't move when I swap eyepieces, yet I can move the scope as necessary without much force. I see no reason why you should move the scope inside the rings/clamshell.

Thats how I do it. Most of the eyepieces that I use with my Tak weigh approximately the same though so I usually just need to add a dab of alt axis tension while I change eyepieces and then go straight on without needing to shift the scope fore or aft.

[waso29]

Which website is that?  It looks like Anacortes, but I don't see such prices on the Anacortes website.

 

Oh, I see now.  Your pic is from two years ago.

 

Why post that pic now????

the listed prices (before the 20% off sale) are still valid:

2230

2440

2680