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What's wrong with a Crayford Focusers?

Rogering1

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FarSide

FarSide

Posted
Posted

I agree with Olly in every respect. I think Crayford sales continue to rise because they are the mainstream of focusers, and rightly so, they are cheap and easily replaceable. But many of us here spend money on our gear, and once we have the telescope bug we buy much more expensive things other than focusers which seem to stray from the mind because their weaknesses are mostly unrecognizable to the 'once-a-weeker'. Personally i think that if you are willing to buy auto-focusers, DSLRs, EQ6 mounts and other expensive bits of kit, then you should consider buying an upgraded focuser that at the end of the day will aid you in just the same way as all of the other bits of expensive kit that we buy.

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JohnC

JohnC

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Very happy with all the crayfords that i have owned.

The one that had slippage once was a moonlite, but this was adjusted and proved ok.

I have only had a dslr mounted so not a great load.

For visual use i really like them.

I saw a feathertouch out at the dark site recently and must admit they are a beautiful piece of kit and in an altogether different league.

If i could afford them they would be my chioce.

However i feel that the crayford fits well in my budget and have no regrets.

Olly is in a different position having to provide a first class service to his clients.

this i think more than justifies the investment and is very much a necessity.

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alan potts

alan potts

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Posted

In my books Crayford focusers are fine, but dont buy a cheap one. I did and I have since bought a Baader which is many times better. The TS site in Germany have many on their books that look great but are not. I have two of their GSO type focusers on different scopes and in my opinion they both need replacing. I can compare these with the one on my APM and they are not in the same street. I guess the price tags would be miles apart too.

Alan

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ollypenrice

ollypenrice

Posted
Posted

Ooooh no it hasn't (said in best pantomime voice) :icon_jokercolor:

Sales of Crayford focusers continue to rise.

Crayford, Helical and R&P focusers have their pros and cons but ultimately it is the build quality (price!) that determines performance. Your Feathertouch is one of the most expensive focusers on the market. The majority of members would find it difficult to justify the expense and in most instances it would be quite unnecessary. Consider also that at the low-mid price end of the market the Crayford design produces a better product than R&P. A cheap R&P is horrible! And if I am not mistaken the 80 & 115 Altair telescopes you have been endorsing are fitted with Crayford focusers. I assume you are pleased with them.

I agree most of the Crayford focusers supplied with low-mid price telescopes are not good for astrophotography so I understand why you and anyone else imaging with heavy equipment invest in an expensive R&P but the majority of astro-photographers are quite happy using mid-price Crayfords.

If you do find a range of mid-price R&P focusers that perform well please send details because there is probably a gap in the market.

Oh, and you are most definitely 'not' a lunatic :grin:

Steve

Steve, you, are wrong on two counts. I AM a lunatic and I don't endorse AA scopes, I review them!!! :grin: (Seriously, have you ever seen me endorse the fast imaging Newt? I thought it was dire.) To quote from my latest review in Astronomy Now, 'I am not a Crayford enthusiast, but...' I suppose that on SGL I lose my objectivity and banter amongst friends. I would far rather see tha blessed thngs disappear. I really don't trust them. Any thoughts on my lock strip idea? I'm not an engineer. Sure, Moonlite and Steeltrack sales are rising because the standard Crayfords are not fit for purpose. That is not right, though, is it? A new product should work. So, fair enough, I am knocking bad Crayfords over good ones. I accept that.

If focusers are going to be cheap, should they be Crayford or R and P? I'm going to vote for notchy but reliable R and P. Others may disagree. Here is my prediction; cheap scopes will appear with R and P instead of Crayfords over the next 8 years. Watch me lose this one!!! No worries, I'm old enough to take a hit to my pride...

I have a huge respect for your posts. I hope you know that.

Olly

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Peter Drew

Peter Drew

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My "high tec" solution to the problem of weak Crayford action or slippage due to the weight of accessories, in my case a PST body as a mod, is to attach a couple of rubber bands between the moving part of the drawtube to a fixed part of the OTA. This holds the focus action in a relatively weightless situation which is easily controlled by the focus wheel. Cheap and simple. :smiley:

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The Sailor

The Sailor

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Right, since I did not get a reply to my question I decided I had nothing to lose if I am going to replace the Crayford so I took it off the OTA. What a suprise, no wonder I had slippage, the only screws which were nice and tight were the ones attaching it to the OTA, the six screws holding the focusing mech were loose thus negating any tightening of the main bolt. Taking the whole lot apart I found a lot wrong, cleaned up as necessary, reassembled and I now have a nice steady movement of both the main and slow mo, reattached to the OTA I will check with some solar work what I have achieved :).

Jim

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Steve Ward

Steve Ward

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I rest my case....... :evil: ........ :p

While you're about it , have you cleaned up the "flat" on the drawtube ?

They are machined with a slight concave so the roller only touches at the edges , if you carefully hone this flat it will make the world of difference.

Steve.

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The Sailor

The Sailor

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Just done a test, at the moment the camera is attached with a 2" diagonal, a 2" Barlow and a 1.5" adapter, all is looking good, both main and slow mo are working well, no slippage. This is the first time since i bought the telescope that I have had a good focus without resorting to tightening screws, maybe just maybe I have saved myself a few hundred £'s, time to spend it on some eyepieces :).

Jim

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ollypenrice

ollypenrice

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Posted

My "high tec" solution to the problem of weak Crayford action or slippage due to the weight of accessories, in my case a PST body as a mod, is to attach a couple of rubber bands between the moving part of the drawtube to a fixed part of the OTA. This holds the focus action in a relatively weightless situation which is easily controlled by the focus wheel. Cheap and simple. :smiley:

You know, Peter, I had wondered about this myself and hesitated on the grounds of being silly, but it is not silly at all! Now where can I find some elastic? Surely Monique doesn't need all those pairs of...

Olly

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syd_malicious

syd_malicious

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Talk about sweeping statements......the £75 Newtonian the local camera shop is bad so all Newtonians are bad. You probably don't agree with this and yet this thread is doing exactly that about Crayford's.

Surely there are good Crayford's, bad Crayford's and Crayford style focusers etc etc. A blanket statement that Crayford's are bad is far too simplistic. Granted, bad Cryford's are very bad but I have an Optec TCF which has never slipped and hauls many pounds of gear without an issue. It is expensive but, as ever, you get what you pay for.

I am about to upgrade to an even more expensive Crayford that is rated to carry very large loads and I have no doubt that it will.

A quote from a hight end manufacturer "Be aware that all [so-called] Crayford focusers, are not really Crayford focusers. Deceptive advertising by many dealers, trying to take advantage of the Crayford's reputation, offer Crayford-type, Crayford-like or Crayford-style focusers that have very little to do with the true Crayford design. NO radial ball bearings, NO zero-flexure, NO fluid motion, NO ultra-tactile sensitive control, NONE of the above functions that made the Crayford the finest precision focuser on Planet Earth. These non-Crayford focusers typically use plastic pads to simulate Crayford bearings and other inferior construction techniques that diminish the Crayford name. Only a focuser that uses precision radial ball bearings (not slot-car bearings) can [rightfully] be called a Crayford focuser"

Perhaps OTT but it makes a point.

There, reverse rant over.

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Sp@ce_d

Sp@ce_d

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Just done a test, at the moment the camera is attached with a 2" diagonal, a 2" Barlow and a 1.5" adapter, all is looking good, both main and slow mo are working well, no slippage. This is the first time since i bought the telescope that I have had a good focus without resorting to tightening screws, maybe just maybe I have saved myself a few hundred £'s, time to spend it on some eyepieces :).

Jim

I might be tempting fate here but I never had a problem with my 80ED holding the reducer/flattener & the DSLR. Whats more since I added the SW auto focusser it holds focus very well even in between sessions. Now on the other hand my recently accuired ZS66 feels a lot smoother & slick but does seem to need some attention to slipage with the DSLR attached.

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sologuitarist61

sologuitarist61

Posted
Posted

I know the object of the thread was not to come up with a solution, but the question remains, what to you do?

I have a scope with rack and pinion and no matter how I adjust the focuser, it slips. I have another where the same type of focuser works fine, but for me the question is what do I do with the first ? I either use the R&P that I know doesn't work well, I get a decent Crayford, or what .........? There seem to be no other options available.

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ollypenrice

ollypenrice

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For reason or reasons unknown, R and Ps are presently very expensive. I think this will change. In your case I would buy a Steeltrack or Moonlite. Yes, I don't like Crayfords but at present this is probably your best bet.

I just want to bang away at getting some decently priced R ad Ps on the market - but if they are not there we can't buy them.

Olly

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FLO

FLO

Posted
Posted

Ahh......didn't anyone notice my post earlier in this thread about a new £190.00 rack and pinion focuser from APM ?

I did...

We had a visit from APM about a month ago (we considered becoming a stockist) so had the opportunity to examine a couple of their telescopes (the 80/480 and 107/700) fitted with APM R&P focusers. The focuser is as you would expect from an R&P at it's price - not as smooth as their Crayford but with greater load bearing capacity. APM also supply their telescopes with Feathertouch focusers if requested. We didn't become a stockist because their/our business models are not complimentary but APM can be purchased through Astronomia and the Widescreen Centre. They both have showrooms so if you pay them a visit you might be able to assess one yourself.

HTH,

Steve

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John

John

Posted
Posted

The concave surface issue has been there from the start with those Skywatcher crayfords. What baffles me is why a company like Synta (who manufacture Skywatcher) can't machine a short, flat surface on the bottom of a tube :icon_confused:

Having a really flat surface there seems to me to be a critical part of the crayford design - if you can't achieve that then perhaps its best not to try and make the things !

Having said that, the Orion Optics crayford suffers from the same issue ...... :rolleyes2:

This seems to highlight one reason for unwanted slippage (he does ramble on a bit but means well :) ) ..

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