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TAL 150P

chrisgtl

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chrisgtl

chrisgtl

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Hi all,

I have been wanting to get into Astronomy for a while now and recently moved house which allows me to eventually buy a telescope. We now have a large rear garden with concrete path area for a scope to sit.

I have been offered a second hand Tal 150P for £240 - firstly is this a fair price for a 2nd hand Tal 150P? It comes with additional telrad finder and premium collimator. Only two EP's are supplied, a 7.5mm and 25mm - is this suitable or would I also need the barlow lens as supplied with a brand new 150P?

Sorry for all the newbie questions, I see lots of people on here have a Tal 150P so thought you would be able to tell me the facts..

Cheers all,

Chris

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chrisgtl

chrisgtl

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Nice scope, sounds good if it comes with the mount?

Yes comes with the pier mount.

The EPs will get you going but you could certainly do with a 15 or 12mm, not keen on Barlows myself.

The EPs will get you going but you could certainly do with a 15 or 12mm, not keen on Barlows myself.

OK, which EP's would you suggest so I can get an idea of additional costs.

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Astro Imp

Astro Imp

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As far as EPs go you might like to read this very imformative thread:- http://stargazerslou...least-you-need/

I am aware that this does not address your question of cost but gives a good idea of a basic starting point. The amount you spend on EPs depends what you find acceptable in the way of sharpness, contrast, fov etc. You can spend from several pounds to several hundreds of pounds per EP, that is a choice only you can make.

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AndyH

AndyH

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Pics are here

http://db.tt/kFpcb3yn

http://db.tt/xpvWY1pe

http://db.tt/kbhuDGmf

Sent from my Nexus 4 using Tapatalk 2

Ahha. Yes, good. That's the new version. Looks to be in great condition.

I don't see the excellent 8x50 finder. The telrad is a great piece of kit, but the big Tal finder is a cracker. Many folks(other than me) reckon it's one of the best straight through types on the market. Would be nice to have both the Telrad AND the optical finder included ;)

Andy.

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chrisgtl

chrisgtl

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Oh good! He said it comes with all the OEM equipment plus the premier cheshire collimator and telrad finder.

I've bought it and pick it up Fri/Sat.

I have some serious reading to do!

Sent from my Nexus 4 using Tapatalk 2

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AndyH

AndyH

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Excellent news !!

Hopefully Nicnac(and other Tal 150P owners) will see this thread and can help you with any questions.

If you can't wait, here's the user manual that comes with the scope. The mount that your scope is on is called the MT-1. So look for info regarding that one in the manual rather than the MT-3S .

:smiley:

Andy

TAL1,1M,2,150P,150P8 english service manual.pdf

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chrisgtl

chrisgtl

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Just been to pick the telescope up. Everything looks good apart from the primary mirror which looks spotted with dust/dirt. One of the OTA caps is broken and has a hole from where it is cracked, not too bad but he used this one to cover the EP end which means dirt from his shed has settled onto the primary mirror. Shame he didn't use the broken cap for the bottom end instead!

Sent from my Nexus 4 using Tapatalk 2

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Marki

Marki

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Hi Chris

Lots of advice on cleaning mirrors on the forum, so go carefully. Don't' do anything until you have had the scope out under the stars first. You'd really be surprised at how much dirt and dust can get on the mirror before it starts to significantly degrade the views!

All the best - I've read so much about how good these scopes are!

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AndyH

AndyH

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Hi.

Unless the mirror is really rank rotten dirty, then for now, I'd concur with the above advice and leave it as is.

If you feel you need to clean it then bear in mind you can remove the primary mirror cell very easily. It's held in place with 3 screws on the tube. Put a mark or sticker on the tube and cell so that when you put it back on the tube, the collimation might not be far off, if it's moved any. With the cell n mirror off the tube, use a 'bulb blower' to get rid of loose dust/dirt. That may be enough to shift some of the dust/dirt, without resorting to a full mirror clean.

For future reference, I find the following method of mirror cleaning, works perfectly for my Tal mirrors.

Andy.

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chrisgtl

chrisgtl

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Funny you should link me to that video as that is the one I used to clean the primary. The only difference I did was drag the cotton wool over the mirror while it was submerged under water so the weight of the wet cotton wool didn't apply any force to the mirror.

Used deionised water to rinse the mirror thoroughly after soaking the mirror about 5 times, cleaning the plastic bowl and changing the water between each soak.

Primary looks so different now!

On my first viewing with dirty mirror I could just about make out the cloud bands of Jupiter. The second night with clean mirror I could see much better detail on Jupiter. So quite happy I spent all that time cleaning and collimating it. I had a nightmare using the collimator for the first time, spent about 4 hours trying to get it spot on, with plenty cooling off periods between each attempt.

I think it is done now, all the circles seem central now, its confusing to determine when the reflections are playing tricks on the brain so used the paper in the OTA trick and also used the brown card to backdrop the secondary.

One thing that I don't understand with my MT-1 stand is the two locking nuts are up against each other and because of the cog like ends they lock into each other. Surely this can't be right? Also the counter balance weights get very close to the little angle adjustment when the telescope is angled towards the horizon.

I was expecting Jupiter to be bigger using the 7.5mm plossl but maybe I was expecting a little too much from a 6" reflector.

If I'm using a 7.5mm EP with my TAL 150P does this mean the magnification is x100? I have been reading about realistic magnification that is usable and seem to think I came across people saying x150 is the limits for good viewing of non-deep space objects?

How long should a telescope be outside cooling down before I start using it? I left it half hour but maybe this wasn't enough?

The scope did indeed come with the original finder so will give that a go sometime. The telrad was good once I calibrated it against Jupiter b

however the glass/plastic window kept fogging up outside.

Sorry for all the questions, thanks for the help all.

Sent from my Nexus 4 using Tapatalk 2

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chrisgtl

chrisgtl

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The 3rd image is about what I got through my 7.5mm EP for reference. I was hoping I would see a similar image through my EP to the 1st image on the link.

Sent from my Nexus 4 using Tapatalk 2

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AndyH

AndyH

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Funny you should link me to that video as that is the one I used to clean the primary. The only difference I did was drag the cotton wool over the mirror while it was submerged under water so the weight of the wet cotton wool didn't apply any force to the mirror.

Totally agree. I haven't cleaned a mirror in an age, but yes, I use that technique too. Better erring on the side of caution.

Used deionised water to rinse the mirror thoroughly after soaking the mirror about 5 times, cleaning the plastic bowl and changing the water between each soak.

Primary looks so different now!

On my first viewing with dirty mirror I could just about make out the cloud bands of Jupiter. The second night with clean mirror I could see much better detail on Jupiter. So quite happy I spent all that time cleaning and collimating it. I had a nightmare using the collimator for the first time, spent about 4 hours trying to get it spot on, with plenty cooling off periods between each attempt.

I think it is done now, all the circles seem central now, its confusing to determine when the reflections are playing tricks on the brain so used the paper in the OTA trick and also used the brown card to backdrop the secondary.

You might already know this, so apologies if you do ! When you use at least 150x on a bright star(pole star might be bright enough), once focused, turn the focuser handwheels, so the focuser tube moves in towards the scope tube, thereby unfocusing the star slightly(this is called infocus). Inspect the unfocused star rings/disc. It should show the dark spot, which is the secondary shadow and rings. They should be concentric and not off to one side. Do the same in the outfocus position. If you think it needs a tweek, loosen the Tal Primary mirror cell's central locking thumbscrew, then start tweeking one or more of the three collimation thumbscrews. Once you're happy, gently tighten the locking screw. Good thing about the 150P, due to it's short length, is you should be able to keep an eye on the eyepiece whilst doing this.

One thing that I don't understand with my MT-1 stand is the two locking nuts are up against each other and because of the cog like ends they lock into each other. Surely this can't be right? Also the counter balance weights get very close to the little angle adjustment when the telescope is angled towards the horizon.

Ahha ! You've noticed the lock knob knocking thing too ;) This is defo a design flaw in an otherwise excellent mount. In my opinion, one knob should be shorter than the other. It's really only relevant when the scope is being used with a Newt scope on top. With a newt on top, the two large slo-mo wheels need to be both at the same side, for easy access. Not so, when a refractor is on it.

Here's what to do. Don't fully tighten up both RA & DEC lock knobs. The idea is to tighten them enough so the scope doesn't slip, but not so tight so the scope can't be moved by hand. In effect you are using the scope similar to the way dobsonian owners use theirs. So, you should be using these lock knobs as tensioners, if you see what I mean. You should be able to tension both axis/both knobs, in such a way, that they should 'miss' each other as they pass.

Mmm. You've lost me regarding the counter weight query? Could you explain more? Ta.

I was expecting Jupiter to be bigger using the 7.5mm plossl but maybe I was expecting a little too much from a 6" reflector.

If I'm using a 7.5mm EP with my TAL 150P does this mean the magnification is x100? I have been reading about realistic magnification that is usable and seem to think I came across people saying x150 is the limits for good viewing of non-deep space objects?

Yup, that's the mag that'll give. Jupe at 100x WILL be a small disc. I usually use at least 150x, more, perhaps up to 200x, if the atmosphere is steady(twinkling stars high up in the sky, away from the horizon, is a bad sign for planetary/moon viewing). If you have a range of eyepieces etc, you can choose the magnification to suit the target and conditions. Every night could be different !

How long should a telescope be outside cooling down before I start using it? I left it half hour but maybe this wasn't enough?

Depends the difference in temps, inside to outside. A tell tale sign that the mirrors haven't cooled enough, is when you unfocus a star at high power, you can hardly see the rings inside the disc. It's all wavy, like a heat haze rising from a road.

The scope did indeed come with the original finder so will give that a go sometime. The telrad was good once I calibrated it against Jupiter b

however the glass/plastic window kept fogging up outside.

Hopefully a telrad user can help you. I don't have one.

Sorry for all the questions, thanks for the help all.

Nae problemo. Happy to help out.

Sent from my Nexus 4 using Tapatalk 2

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chrisgtl

chrisgtl

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Can I patent protect the term, 'lock knob knocking thing' ?

Staggering use of the english language........ :icon_redface:

My lock knob knocking is rubbing against my other knob.......I'm getting advice from my GP.

Sent from my Nexus 4 using Tapatalk 2

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