Bressers Bargain CaK Scope???

[marktownley]

I've been for some time using a Bresser 127/1200 refractor stopped down to 80mm to give me f15 when imaging in CaK, but noticed this cheeky scope had come out

bresser_messier_102l_1350_1.jpg (347.04 KiB) Viewed 2964 times

https://www.firstlightoptics.com/bresse ... r-ota.html

At just over £300 compared to the just over £400 of the 127/1200 it is even more of a bargain. Stopping it down to 90mm would give f15 so offering a bit more resolution. It will also be a lighter scope. It also comes with the Hexafoc focuser, and while no Feathertouch isn't a slouch either. You can even upgrade the focuser with the 1:8 gear set reduction.

I'm very close to getting one, infact the only thing that is stopping me is that I will get in trouble for buying another large scope to clutter the house.

I think the 100/1350 is quite the bargain!

Mark

[Dennis]

Looks like your new scope Mark. Exchange the smaller for the bigger one if it performs.

[Rob63]

I spotted that one last week but at a FL of 1350 it wouldn't suit my Lunt B1200
Note that it doesn't have dual speed focuser but you can add an 1:8 Gear-set as an extra (costs another £93 though)

[marktownley]

Looks like your new scope Mark. Exchange the smaller for the bigger one if it performs.

I like to have a 'range' for different seeing conditions

[marktownley]

but at a FL of 1350 it wouldn't suit my Lunt B1200

Why?

[Dennis]

I spotted that one last week but at a FL of 1350 it wouldn't suit my Lunt B1200

Mine performs fine with FL of 12m

[Rob63]

but at a FL of 1350 it wouldn't suit my Lunt B1200

Why?

Well, according to Lunt's website "B1200: For telescopes up to 100 mm aperture and 1200 mm focal length"
or is this not accurate? the only difference they mention between the B600, 1200 and 1800 is the suitable focal length

[marktownley]

Well, according to Lunt's website "B1200: For telescopes up to 100 mm aperture and 1200 mm focal length"
or is this not accurate? the only difference they mention between the B600, 1200 and 1800 is the suitable focal length

That's only if you want to image full disk, even then I would debate their numbers. 90mm f15 I would say are imaging closeups rather than full disks.

[EdAstle]

I just bought a 2nd hand Vixen "Super Polaris 80M". fl 910, f/11 ish.
No tripod so it's just an 80M

It was £25 short of this new Bresser.
Impulse purchase. Always wanted an old school Japanese Vixen.

But for 25 notes more I could have got a new "up to date" slightly larger scope like this.
Quandaries quandries!

The solution to your problem Mark re "get in trouble for buying another large scope to clutter the house"
is to buy a 200mm frac and hide inside all the smaller fracs

[Rob63]

Well, according to Lunt's website "B1200: For telescopes up to 100 mm aperture and 1200 mm focal length"
or is this not accurate? the only difference they mention between the B600, 1200 and 1800 is the suitable focal length

That's only if you want to image full disk, even then I would debate their numbers. 90mm f15 I would say are imaging closeups rather than full disks.

Thats good to know Mark, thanks. Looks like it would be ideal
I will let you be the guinea pig for this

[Rob63]

I spotted that one last week but at a FL of 1350 it wouldn't suit my Lunt B1200

Mine performs fine with FL of 12m

12m ?
can you point me to any images Dennis, I'd love to see that setup (I'm guessing it's not a standard refractor )

[Dennis]

I spotted that one last week but at a FL of 1350 it wouldn't suit my Lunt B1200

Mine performs fine with FL of 12m

12m ?
can you point me to any images Dennis, I'd love to see that setup (I'm guessing it's not a standard refractor )

C9.25. Well in fact it was a bit more then 12m i guess..
viewtopic.php?t=42074

I too think that apertures of 80 or 90mm and upwards are not full disk setups anymore. Way too much resolution power.

[TareqPhoto]

Isn't it about the camera also talking about full disk? I mean a camera such as ASI1600 or 183 are larger sensors than all or most planetary cameras in favor of FPS, so if i use 174 or 178 or even 432 [equivalent to P1 Apollo M Max] with 1200-1400mm then maybe with 1600 for example it will be full disk.

I looked at this scope, and also TS Optics 102mm F/11 which is ED and much more expensive, but a vendor just messaged me offered me a triplet 106mm at great price and another scope as ED doublet 96mm, so i will buy both and use 96 for solar stopping it to 70mm maybe or even 60mm, nice price being as a doublet with a reducer and hard case and good shipping all at nice price, so i will pass this 102 or other 102, i could think about using 106 too stopped down if necessary.

[marktownley]

My experience is that doublets (stopped down) perform considerably better than (more expensive) triplets (also stopped down). That increase in the thickness of glass just robs the exposure time when imaging in CaK.

IMHO, one of the important factors with CaK and imaging is correct sampling with the focal ratio and the camera pixel size.

[TareqPhoto]

My experience is that doublets (stopped down) perform considerably better than (more expensive) triplets (also stopped down). That increase in the thickness of glass just robs the exposure time when imaging in CaK.

IMHO, one of the important factors with CaK and imaging is correct sampling with the focal ratio and the camera pixel size.

That is why we have like more than 4 planetary and solar system cameras, 3 mono for now, looking for selling one and replace it with something else newer but same pixel size.

[TareqPhoto]

I can't wait to get my mount i did order yesterday or before yesterday, i have to wait for it, but now i am thinking about another mount of same size or model but designed for solar, which is SolarQuest, this and the one i ordered will definitely keep me imaging more than my AZ-EQ6 so heavy one, will see what i will get, and hopefully i can order the doublet I've got an offer for.

[OlegLviv]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

[TareqPhoto]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

[OlegLviv]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

Yes I have but there is not much aperture, + f13.5 better f10, and wants modification this telescope for Cak

[marktownley]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

It's about the native focal ratio the CaK filter see's Tareq...

[TareqPhoto]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

Yes I have but there is not much aperture, + f13.5 better f10, and wants modification this telescope for Cak

Modification or magnification you mean?

Your 80 is F10, you stop it down and it is about f13.3 then anyway, but not big aperture yes.

[TareqPhoto]

I bought Bresser 102/1350 a few days ago and planed use with Cak b1200....but I see than with 183mm have less vignettive in corner, but with 290mm or 429mm will be better.

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

It's about the native focal ratio the CaK filter see's Tareq...

I kept thinking about it, but after i tested mine i feel it is just not a big deal really, my 80mm stopped down to something like 45mm f9 was more than enough really, and if i want to go with close up i will never look or use anything less than 120mm-150mm aperture for that stopped down, sometimes i feel maybe i buy something like 100mm f15 rather than 150 stopped down to 100mm f15, but i don't know what will be the difference, i once asked about it and i remember you recommended the larger one stopped down than the native.

[OlegLviv]

You have Stellamira 80 ED, you don't need Bresser 102 actually, but congrats anyway.

Yes I have but there is not much aperture, + f13.5 better f10, and wants modification this telescope for Cak

Modification or magnification you mean?

Your 80 is F10, you stop it down and it is about f13.3 then anyway, but not big aperture yes.

Yes yes Modification

[TareqPhoto]

Yes I have but there is not much aperture, + f13.5 better f10, and wants modification this telescope for Cak

Modification or magnification you mean?

Your 80 is F10, you stop it down and it is about f13.3 then anyway, but not big aperture yes.

Yes yes Modification

Ok, i hate you, now i feel i want to buy that scope

[marktownley]

i feel maybe i buy something like 100mm f15 rather than 150 stopped down to 100mm f15, but i don't know what will be the difference, i once asked about it and i remember you recommended the larger one stopped down than the native.

For CaK, it is about eliminating spherical aberration in the scope - stopping it down does this.

[TareqPhoto]

i feel maybe i buy something like 100mm f15 rather than 150 stopped down to 100mm f15, but i don't know what will be the difference, i once asked about it and i remember you recommended the larger one stopped down than the native.

For CaK, it is about eliminating spherical aberration in the scope - stopping it down does this.

You mean it doesn't matter how to get up to F10 or F15 as long it has enough focal ratio to resolve CaK, be it native or stopped down, right?

How do i know if the spherical aberration in the scope is eliminated? I mean if i have a scope with F5 and i stopped it down to F8 is it also spherical aberration eliminated? or it must be like F10 or slower for CaK anyway?

[marktownley]

i feel maybe i buy something like 100mm f15 rather than 150 stopped down to 100mm f15, but i don't know what will be the difference, i once asked about it and i remember you recommended the larger one stopped down than the native.

For CaK, it is about eliminating spherical aberration in the scope - stopping it down does this.

You mean it doesn't matter how to get up to F10 or F15 as long it has enough focal ratio to resolve CaK, be it native or stopped down, right?

How do i know if the spherical aberration in the scope is eliminated? I mean if i have a scope with F5 and i stopped it down to F8 is it also spherical aberration eliminated? or it must be like F10 or slower for CaK anyway?

Stopping down the scope (for CaK) reduces spherical aberration - f15 works fine. Stopping a scope down and native are not the same thing.

If you have an f5 scope and stop it down to f8 it will still be full of spherical aberation. Yes, f10 or slower, f15 is better.

[TareqPhoto]

For CaK, it is about eliminating spherical aberration in the scope - stopping it down does this.

You mean it doesn't matter how to get up to F10 or F15 as long it has enough focal ratio to resolve CaK, be it native or stopped down, right?

How do i know if the spherical aberration in the scope is eliminated? I mean if i have a scope with F5 and i stopped it down to F8 is it also spherical aberration eliminated? or it must be like F10 or slower for CaK anyway?

Stopping down the scope (for CaK) reduces spherical aberration - f15 works fine. Stopping a scope down and native are not the same thing.

If you have an f5 scope and stop it down to f8 it will still be full of spherical aberation. Yes, f10 or slower, f15 is better.

Ok so in another word it is that the much slower the scope the better of it for CaK, now i wish to use my Mak for that because it is f15 native anyway, but i won't spend fortune to find a safety frontal ERF to be used for CaK, although i saw some used reflectors like Newt for that.

Well, i tried hard to buy everything i can and still missing items, so i don't do imaging like one day/time after another per type of solar, either i image all solar types filters at once or none, i stopped so long time and i also will do DSO and planetary, so i will not spend much more time doing only one type of imaging per day/night and then i spend everyday and every night collecting new data/results, i ask a lot about equipment, and when i test one or two and i know it works then i add more to complete it, happy with my last once test CaK and Ha, means i can add more, WL shouldn't be any more difficult, but you said it needs a better scope a bit over a achromat choice.

[marktownley]

now i wish to use my Mak for that because it is f15 native anyway, but i won't spend fortune to find a safety frontal ERF to be used for CaK,

We're talking about refractors here Tareq. Don't use a MaK for CaK.

[OlegLviv]

As for me Refractors best of the best for sun.

[TareqPhoto]

now i wish to use my Mak for that because it is f15 native anyway, but i won't spend fortune to find a safety frontal ERF to be used for CaK,

We're talking about refractors here Tareq. Don't use a MaK for CaK.

In fact i want to use the Mak for anything, if not CaK then Ha, if not Ha then WL, but definitely not a must.

As refractors, and it is about Bresser here, i am still have a plan to get the Bresser 152mm, not sure when and why and how, but hopefully one day i can, it will be my main scope for close ups of the sun.

[TareqPhoto]

As for me Refractors best of the best for sun.

Definitely, i won't risk with reflectors anyway, just wish to give them a chance if possible, but not as a risk.

[TareqPhoto]

My scope 106mm arrived and delivered to me, the vendor made an aperture mask for it down to 70mm, so hopefully i will give it a try and see, just not sure what kind of protection i need if i will use CaK as i don't want to block this band using one of those UV/IR blocking filters, and as long it is 106 stopped down so maybe i can try close ups with it using much smaller sensor cameras.