Bresser Messier NT150L f8 Newtonian

[alacant]

Hi. Well done. You'll love it I'm sure.

You seem to have a different beast. Ours has an aluminium tube, we don't see spikes around the stars and the focuser doesn't protrude, even with a dslr.
To prevent tube flex, we spread the tube rings on a long Losmandy plate and fixed a rigid rail to tie the top of the rings. Or you could use an oag. A few bits and bobs. HTH and good luck.
  

Edited August 27 by alacant

[900SL]

3 hours ago, Astronomist said:

I fitted the secondary holder on my Bresser  with a thin steel washer to stop the screws digging into the aluminium secondary holder, very easy to precisely set the rotation now. I don't know if there happens to be a washer the right size for the smaller holder on the 6", I got lucky and found the right size on aliexpress. 

It looks like the top diffaction spike in the vega image is two spikes, is one of the vanes twisted or otherwise deformed?

BTW my 10" has the same huge flares from the primary clips (see below), I assume Bresser's clips overlap the mirror more than other manufacturers?

There should be a trophy for 'tip of the day'. I hereby virtually award it to you. 

Secondary now 'washered' and rotates like a charm.

[ONIKKINEN]

6 hours ago, Astronomist said:

fitted the secondary holder on my Bresser  with a thin steel washer to stop the screws digging into the aluminium secondary holder, very easy to precisely set the rotation now

Thanks, i actually needed something like this for my new 10" that TS screwed up the spider orientation with. Tip of the century!

@900SL Did you have a mirror fan already? The slightly comatic looking stars look suspiciously like they were affected by thermal plumes inside the tube. Your tube is very long, so i think there is greater chance of the slight temperature difference causing this as the light path through the turbulent air is quite long.

 

You can just velro a fan to the bottom of the tube over the hole in the center. Noctua fans are good quality and low vibration, you can pick them at Verkkokauppa (just pick a 12V model and wire it yourself to a DC 12V supply). Velcro strips you'll find from Biltema.

* And also, get an OAG. Much better with a newtonian and more resistant to tube wobbles or other stability woes.

Edited August 27 by ONIKKINEN
*

[900SL]

21 hours ago, alacant said:

Hi. Well done. You'll love it I'm sure.

You seem to have a different beast. Ours has an aluminium tube, we don't see spikes around the stars and the focuser doesn't protrude, even with a dslr.
To prevent tube flex, we spread the tube rings on a long Losmandy plate and fixed a rigid rail to tie the top of the rings. Or you could use an oag. A few bits and bobs. HTH and good luck.
  

Yes, you appear to have a different scope

Looks like Bressers supplier has changed a few things. I found this post, the owner had the same issue reaching focus with a DSLR attached directly to the M42 thread on the focuser.

 

I will try moving the secondary up a touch. The height of the adapter probably doesn't help (Bresser use a 2" to 1.25" to m42 arrangement, nearly 30mm in depth. And using a 533 will reduce the backfocus

 

 

 

[900SL]

16 hours ago, ONIKKINEN said:

Thanks, i actually needed something like this for my new 10" that TS screwed up the spider orientation with. Tip of the century!

@900SL Did you have a mirror fan already? The slightly comatic looking stars look suspiciously like they were affected by thermal plumes inside the tube. Your tube is very long, so i think there is greater chance of the slight temperature difference causing this as the light path through the turbulent air is quite long.

 

You can just velro a fan to the bottom of the tube over the hole in the center. Noctua fans are good quality and low vibration, you can pick them at Verkkokauppa (just pick a 12V model and wire it yourself to a DC 12V supply). Velcro strips you'll find from Biltema.

* And also, get an OAG. Much better with a newtonian and more resistant to tube wobbles or other stability woes.

Kiitos Oskari. I'm browsing Verkkokauppa right now for a 12V fan. Bought a replacement fan for the 533 OSC from them previously (original had the vibration issue) 

 

OAG.. I was trying to avoid dumping more cash into this, but hey, Newtonians...  (I like tinkering so I could get to like a (good) newtonian)

[alacant]

35 minutes ago, 900SL said:

using a 533

Yes, should be much easier. You'll have  an extra ~40mm.
The other trick is to use a low profile t-adapter on your dslr with a m48 extension tube to form a nosepiece. This will get you an extra 10mm:

  

Edited August 28 by alacant

[900SL]

I might see if I can find an m70 something to m42 adapter,  for direct connection. 

[900SL]

33 minutes ago, alacant said:

Yes, should be much easier. You'll have  an extra ~40mm.
The other trick is to use a low profile t-adapter on your dslr with a m48 extension tube to form a nosepiece. This will get you an extra 10mm:

  

That's a good idea, means I can be sure of getting focus.