Mak focus backlash - how much is too much?

[Mr niall]

Hello all

i received a skymax 102 for Christmas, I’m having trouble with focusser backlash and I was wondering how much is reasonable for a Mak?

Im getting a full turn and a quarter of the focusser knob before the mirror engages in either direction and I’ll be honest it’s really getting me down. It’s making fine focus almost impossible; if you have a fraction past focus you spend the next ten minutes spinning the knob in the other direction until it engages again - but as it engages without warning you likely as not zoom back past focus and out the other side and have to start again!

Ive had a C90 and a 127 in the past and they were perfect 

many thanks

Niall

[banjaxed]

Hi Niall,

Sounds to me like you have a faulty focuser, you should be able to get it replaced if you have only had it since Christmas.

[Waldemar]

it should be adjustable… no doubt it is, but I don't own one, so can't tell you.

Other people will chime in with more knowledge about this particular scope. Don't dispair!

[Geoff Lister]

20 minutes ago, Mr niall said:

Ive had a C90 and a 127 in the past and they were perfect 

I, too, have both, and the backlash is, at most, a couple of degrees, and only really noticeable when teasing the fine detail in views of Jupiter and Saturn, with magnifications of over 100x.

I think that there is something wrong with your 102. I am not aware of any adjustments of the focus mechanism that would not affect warranty.

Geoff

[JamesF]

I agree.  It can be adjusted, but probably only if you take the OTA apart.  It sounds from the description as though something has come loose inside (or wasn't sufficiently tight in the first place).  I'd get it replaced.

James

[chiltonstar]

I have two maks and it sounds excessive to me - both mine have a little backlash ands a small amount of image shift at high magnifications. I have heard (I have never tried it though) that winding the focus to one extreme and back again can reduce/eliminate focus shift - maybe worth trying, if not back to the supplier I think as it sounds as though something has not been tightened internally.

Chris

[johninderby]

It does sound like something is amiss with it. With a new scope just return it. Did you buy it from FLO or somewhere else? A small amount of backlash is inevitable but should be only minimal.

There is a solution to the problem with backlash of small maks but a 1.25” crayford with adapter would cost more than the mak. 

Edited January 2, 2020 by johninderby

[joe aguiar]

I also agree that way too much play for a full turn or more , something coame off inside maybe.

is there aperson near u that's into this hobby or store?

its not really too hard to open it up and check if rod came out of the hole inside but if your brand new I could see someone not wanted to do that.

if not put up another tread of anyone who knows the hobby well close to u

joejaguar

[johninderby]

The small Skymax maks use a large rubber O ring to seal the back casing which often breaks when you take it apart.

Edited January 2, 2020 by johninderby

[Mr niall]

Thanks for the responses all it’s always great to have people to ask for advice it can be such a lonely hobby sometimes especially when you are confused!

I did indeed by it from FLO but bought it in mid November as a Christmas present (December pay was already accounted for as kids wanted expensive computers and playstations!). I’m kicking myself for not testing it while the returns window was open but that would have been cheating wouldn’t it😉.

But from what I’m reading above it sounds like I may have a warranty claim after all. I was sort of hoping it was one of those things that may be easily fixed but doesn’t sound like I can easily fix it my self. FLO suggested the thing with winding the focusser back and forth too but that didn’t work. I’ll see what they think.

Thanks for the advice.

[banjaxed]

13 minutes ago, Mr niall said:

Thanks for the responses all it’s always great to have people to ask for advice it can be such a lonely hobby sometimes especially when you are confused!

I did indeed by it from FLO but bought it in mid November as a Christmas present (December pay was already accounted for as kids wanted expensive computers and playstations!). I’m kicking myself for not testing it while the returns window was open but that would have been cheating wouldn’t it😉.

But from what I’m reading above it sounds like I may have a warranty claim after all. I was sort of hoping it was one of those things that may be easily fixed but doesn’t sound like I can easily fix it my self. FLO suggested the thing with winding the focusser back and forth too but that didn’t work. I’ll see what they think.

Thanks for the advice.

If my experience with FLO is anything to go by they will make sure you are completely satisfied with your scope whatever it takes.

Edited January 3, 2020 by banjaxed

[johninderby]

FLO does have an extended return time at Xmas to allow for things bought earler for Xmas but that couldn’t be used until Xmas. 

You will have no problems with returning it to them. just contact them and they will organise the collection for you.

Edited January 3, 2020 by johninderby