105mm CFF telescope has arrived!

[Slawomir]

Ahoy Comrades!

Happy days and cloudy nights have arrived to SE Queensland!

A few months ago I decided to upgrade my 4” ED doublet from TS. It served me very well over the past three years, and I have learnt a fair bit about the never-ending journey to perfection in taking pretty astronomical pictures.

After upgrading my mount last year I started wondering whether I would be able to get even better data with premium optics. So after a lot of thinking, reading, thinking, reading…I decided that for the time being I want to stick with a 4” refracting telescope. Then it came down to picking the dream telescope that will be most suitable for my mount and camera and being portable at the same time. Cutting long story short, I contacted CFF telescopes and rather quickly ordered their 105mm f/6 oil spaced refractor.

Catalin from CFF has been extremely helpful, quick in responding and he made everything possible that I was getting what I wanted, including customised carry case, which in itself is a piece of art. He even designed and made custom adaptors needed for my specific camera, so it matches perfectly with CFF’s humongous (to me anyway) field flattener and also with the Riccardi reducer. The flattener offers 44 mm corrected imaging circle at f/6, while the Riccardi speeds the telescope to f/4.5 and the imaging circle is about 40 mm (I need to double check that number). FT true 3” focuser ensures that pretty much all light gathered by the lens is passed onto the field flattener. In one of the photos I placed a 1.25” diffraction grating next to the field flattener. It is a real shame that my current camera’s sensor is so tiny!

As expected, clouds have intensified after the delivery so I am yet to take the telescope out. I will certainly peek through it with my TeleVue eyepiece (yes, I have one eyepiece!) before I attach the camera to the telescope.

The telescope came with optical test report signed by CFF’s optician Pal Gyulai who hand figured the lens. There are a lot of numbers in the optical report that I am yet to understand, but a few numbers caught my eye - RMS wavefront error of 1/62.2 waves, Strehl ratio of 0.990 (both at 550nm) and also RMS surface error of 4.422nm. I think these are outstanding for an f/6 refracting telescope, so I am expecting nice tight stars even with RGB filters.

I will write an update once I have an opportunity to test the telescope visually, at least.

Thank you for reading.

Suavi

P.S. I knew I had to take unpacking photos, otherwise “it did not happen”…;)


P.P.S. Just confirming the fully corrected circle with the Riccardi 0.75 reducer is indeed 40mm

[codemonkey]

Very nice Suavi! You're getting yourself some pretty sweet gear lately; I'm jealous! Looking forward to seeing some nice sharp images.

[Atmos]

Fantastic acquisition Suavi!! Very jealous!

[Slawomir]

Thank you Lee and Colin.

Yes, I think I am good with my astro gear for a while. Now just need to be patient and wait till we move to a new place that will be more conducive for astro-imaging. In the meantime will try to take a few quick snapshots of the night sky and try taking low resolution star spectra. Has anyone got a cloud repellent?

[Atmos]

I do wonder what the polychromatic strehl is! It'll certainly be good but I do wonder how good :) The number itself won't
See any different except to satisfy my morbid curiosity hehe

[Slawomir]

I have no idea Colin, but to my knowledge my new telescope is diffraction limited within the visible spectrum. Refracting telescope at f/6 will certainly have lower than 0.990 Strehl ratio for blue and red light.

On the report I also got multiple Zernike coefficients and all are near zero. For example Z8 is 0.01 and as I understand this coefficient is a measure of spherical aberration. Several other coefficients are in the order of ten thousandths (4 places after decimal place).

I guess we will need to wait for my first image taken with my new babe :-)

As a side note, if my memory serves me well, I remember reading on CloudyNights that CFF makes also planetary series with longer focal lengths, and their f/10 105mm telescope had/has Strehl ratio equal or greater than 0.995 from red to blue. Now, peeking through such telescope on a clear night would be a very special treat :-)

[Slawomir]

While I am waiting for some time off work to test the telescope...images of a beautiful 3.2" FT focuser and dedicated corrector that came with the telescope. It is a rock solid beast of a flattener! I do not expect any vignetting on my ICX814 :lol:

[RickS]

Congrats, Suavi!

[Wavytone]

Wow.. nice scope, if the optic really are that good !

but... get yourself a sharpie pen and blacken those edges - the scattered light from that last element is atrocious.

[Slawomir]

Thank you Rick!

Yes Wavytone, I also hope that the lens will delver, and my expectations are very high since I have been looking for a perfect system.

I'm not worried about reflections in this photo form the inside part of the corrector, as I took the images from the camera's side, with a flash and at an angle that light will not/should not hit it. Similar brighter parts are also present in the Massimo Riccardi reducer that I have, when I take photos in the same way. Anyway everything will be revealed in first test images.

BTW, I would never ever use a pen on a lens, brand new one in particular, as it would void warranty...

EDIT: Weather permitting will have a peek through the new telescope tonight.

[Slawomir]

Being an imaging guy I currently only have hardly used one TeleVue low magnification eyepiece and one even less used TV barlow...nonetheless I was curious how this telescope compares visually with my previous mass produced ones, so taking advantage of clear skies, I had a peek through the new telescope.

First of all, it was not very easy navigating the mount with my laptop while looking through the eyepiece. A hand controller or at least a game pad would make life easier.

But apart from that, it was a true joy just slewing across the sky. Stars were pinpoint and some had natural delicate colour - red, blue, orange points of light. Open star clusters were simply stunning. My low magnification eyepiece hardly challenged the telescope, but these were the sharpest stars I have ever seen. Inside focus and outside focus diffraction patterns looked identical with perfectly centred diffraction rings.

In spite of being purely imaging guy, I am now tempted to look into getting a few nice eyepieces that will complement this beautiful telescope, and I think I may start having an occasional peek through the telescope in between imaging sessions. I think that says something about this telescope.

[Atmos]

I should get out doing visual more often... maybe when the mosquito plague buggers off!
Not wanting to get Ross River Fever :/ I went out before to make sure that my stars were coming out round and I could wave my hand around and feel myself hitting them mid flight :/

Really glad you're enjoying your new scope! I'd LOVE one of the 160/180mm super planetaries :)

[RobF]

Quality rig Sauvi for a guy that cares about quality imaging.
Not sure about this talk of visual though. Be gone evil spirits!! :lol:

[Camelopardalis]

Looks a beauty Suavi :thumbsup: hope you've fitted the camera now as it's still clear :D

[The Mekon]

Suavi,

may I ask did you import the CFF yourself or go through the local distributor. And how long did you wait for delivery?

I'm thinking of a 140mm CFF as my "final one scope for rest of life"

Edit - my questions are a bit dumb, Suavi, careful reading of your posts indicate you ordered direct and probably waited less than 6 months. (That's what Astro-Physics offered in their early days.)

[Slawomir]

Thank you gents!

Colin- we have similar problem with mossies, I do not come outside the house at night without a repellent on. I figured it is better to have some chemicals on my skin than pathogens/parasites in my body :lol:

160/180 mm refractor would be nice for sure...but that means a larger mount would be needed too!

Rob - yes, my partner agrees- no more spendings on astro gear! :lol:

Dunk - I will need to wait for school holidays before I will take the first image with the new telescope - have too much work at this time!

John - I waited just over 3 months. Delivery from Europe took 4 days. I recommend writing directly to Catalin - you will find him very helpful and he will happily answer any questions you might have. Thus you will be able to clarify any points in regards to your dream telescope and with your planning. I nearly went for their 132mm telescope, but decided that 105mm will be more suitable for me at this stage for imaging with my camera.

[SimmoW]

Looks lovely Suavi. Never heard of the company so I must look them up.

So your pics will be even sharper and more impressive in future? :scared2: :scared2:

[Merlin66]

I first came across Catalin Fus way back in 2009. He helped me with some very critical objective prisms....
Lost touch when I moved to Belgium/ Australia but I'm glad to see he is following his dream.

[traveller]

That's a wonderfully crafted scope Suavi, a real keeper.
Love to see some images off that once the moon phases off.
Bo

[Slawomir]

What about a 200mm, hot off the press...http://www.cfftelescopes.eu/images/200mm/IMG_1247%20v2%20-%20web.jpg

Ken, he certainly is following his dream.

Thank you Simon for your very kind feedback - so my next image better has at least some traces of aesthetics :lol:

Yes Bo, I also can't wait to start collecting data for my next image...counting down days to school holidays :)

[The Mekon]

Suavi,

Well I have just done it! Sent the deposit for a 132mm F6.9 tonight.
I must say you are correct, Catalin is a delight to deal with.
Interestingly, the 132mm is listed as a limited edition with 10 being made. I would have thought this meant they made 10 lenses and would assemble the tubes as orders came in. In fact it is the opposite - tubes are all ready waiting for lenses.
Hopefully will have this scope by springtime!

Thanks for your encouragement.
John

[Slawomir]

That's wonderful John. Really happy for you.

Having fine glass hand figured especially for you by a master optician and then skilfully assembled into a mechanically excellent telescope is quite unique IMO, and therefore using such fine equipment adds joy to this passion of ours :thumbsup:

[Slawomir]

A quick update.

Camera adapters unexpectedly arrived today!

Took only 33 days to get here...I was told by the postman these were held up at the airport...honestly we thought these were lost and Catalin kindly offered to make a new set.

Anyway, I am now ready to get back to astrophotography! Happy days! These adapters are very solid and weigh nearly 400 g; luckily the FT can (almost) hold a bucket full of water (have not tested it...) :lol:

The first image is with CFF flattener, the second with Riccardi reducer (sorry about image orientations).

[Atmos]

All looks really nice Suavi!

[RickS]

Glad to hear they arrived, Suavi. Look forward to the first light images :thumbsup:

[Striker]

Looks awesome Suavi

[gregbradley]

That looks like a beautiful scope Suavi. I am not in the market for a scope but if I were I would be tempted by a nice 102mm wide angle scope with a flat field.

If AP contacted me and said they had a 130GTX ready I would go for it.

An FSQ130 sounds nice but no one seems to have posted any images through one that I can find.

An excellent 102 is a fine imaging instrument. Its good to see such a large and solid focuser on a small scope, that's unusual.

What is the corrected imaging circle of this scope? Will it handle a 16803 - 44mm diagonal?

Greg.

[Camelopardalis]

We totally need a drool icon :lol: :thumbsup:

[Slawomir]

Thank you gents!

I am VERY keen to properly test the Riccardi reducer, as well as the flattener. With the Riccardi the scope will be operating at f/4.5, as fast as I would like to go with a refractor and also with 3nm filters.

FT looks very solid and it is certainly a beautiful focuser, but there are a few things I preferred in my Moonlite, specifically I would like motor engagement ring in Boss II to lock in place more firmly, so I knew that the motor is properly engaged. Also, laptop connection with the focuser seems to be occasionally dropping; it never happened with my Moonlite. Already tried connecting it without the hub but the issue remained. It must be either SGP Pro issue or perhaps my laptop is too slow, because it only happens during running an imaging sequence. Again, had no issues like that with my Moonlite and with the same hub, same laptop and with SGP.

Greg, yes, Catalin told me that this telescope has 52 mm illuminated circle (because of machined baffles in the OTA) and 44mm corrected imaging circle at f/6 with their monster flattener. CFF's larger refractors have a larger corrected circle, with their next one up (132mm) having 52 or 55mm corrected imaging circle.

Will report further as soon as I get a chance to properly test the rig.

Suavi

[blink138]

love the pier too suavi, part of the mount or a separate item?
pat

[Slawomir]

The pier- Eagle has been designed specifically for Mach 1. Very sturdy. Got it together with the mount head.

[Slawomir]

Ahoy Comrades!

Last night weather was good so I finally tested the flattener and Riccardi reducer. With the Riccardi at f/4.5 I got a substantial tilt in one of the corners and will need to get a tilt adapter to try rectifying this issue. Elongated stars remained in the same corner as I rotated the focuser, so then I tried just rotating the QSI t-thread adapter and bingo - elongated stars were now in a different corner. Already ordered a tilt adapter to rectify that.

With the flattener at f/6 precise orthogonality is not as much important as at f/4.5, so the stars look acceptable. Nonetheless correcting the orthogonality should help the stars as well, so I will look into that in the following weeks.

As for good news, FT focuser worked flawlessly last night - I suspect previous connection issues were due to interference from cables powering dew heaters. New gear, new challenges...

Managed to get seven 15-minute Ha subs of the headless chicken with the flattener. Image scale is 1.18 arcsec per pixel: http://www.astrobin.com/291983/

Thank you for following this thread :thumbsup:

Suavi

[Striker]

I have been trying to work on the exact same area....looking forward to your results.

[RickS]

Congrats on your first light chicken, Suavi :lol:

[Atmos]

I've had far worse tilt than that Suavi! Looking good though, once you get it all failed in you'll be humming along. I've been imaging at 1.158"/pixel (very similar to yours) and find it worthwhile drizzling a lot of the time. Even if all it does is get you from 2" to 4" FWHM, i find it allows you to process a little harder (albeit several times longer).

[LewisM]

Epic typo there Colin...FAILED IN....LOL

[DJScotty]

That looks nice Suavi.

Nice Bok (bok bok buckaw!) globules! (Someone has to have done that joke before right!)

[gregbradley]

Beautifully sharp Ha image. I agree the tilt is minimal. Bottom right corner?

A little bit of brass shim would correct that. It probably needs to pack out the top left corner looking at the camera from behind it.

Which camera is this again? QSI690? I like the tiny stars.

Greg.

[Slawomir]

Thank you all for your replies and advices. I will try to sort out the tilt soon (hopefully).

I would like to use the telescope with the reducer at f/4.5 for narrowband, and perhaps with the flattener at f/6 for some galaxy chasing one day.

Added a bit of data to the chicken (4hrs 15min in total). It is still undercooked but hopefully will turn out alright when I get enough data. Dozen of flats, bias and a stretch were applied.

http://www.astrobin.com/full/291983/B/?nc=user


It is soooo good to be imaging again! :)
Suavi

EDIT: Sorry, forgot to answer your question Greg. Yes, it is QSI 690. Wouldn't swap if for anything at this stage, maybe with the exception of FLI 16200...

EDIT #2: Just read interesting impressions from a user of a smaller brother of my CFF105mm - looks like CFF is really crafting nice telescopes: https://www.cloudynights.com/topic/552552-cff-92mm-f6/?p=7828234

[Slawomir]

Hi all,

Last night I managed to significantly reduce tilt with the Riccardi reducer. It took 0.1 mm of camera adjustment to correct it. There is some slight curvature still present, but not sure if that can be corrected with playing with the spacing. It might be as well a limitation of the Riccardi, so I think I will leave things as they are. I have learnt that precision is essential with a refractor at f/4.5...

A star field for a reference: http://www.astrobin.com/full/293135/0/

It's imaging time!

Suavi

[LewisM]

There is an as-new 130GTX on the 2nd page of the ice trades...

[Slawomir]

Well, I thought of testing the CFF flattener as well.

Link to a star field: http://www.astrobin.com/full/293190/0/?nc=Slawomir

Now have a dilemma, image with the flattener or with the Riccardi reducer...:question:

[Atmos]

I think your biggest issue is tilt. At F/5 I was finding that anything more than 0.1mm tilt would be noticeable in the corners. With your reducer you're getting more than that AND shooting at F/4.5.

With the flattener you're getting a bit of tilt with quite small pixels which can exaggerate the issue.

[Slawomir]

Thank you Colin for your advice.

I used to think that unlike big sensors, a small CCD like ICX814 is easy for imaging and more forgiving in terms of perfect alignment. Well, tiny pixels highlight any misalignments very well! :lol:

After recent investigations I realised that I may need to move the Riccardi reducer in by about 1-2mm to flatten the field. I agree, there is a tilt with both units and Catalin very kindly offered to make an adjustable adapter that will help me to tune in spacing and tilt. Also, moving the flattener in by 1mm will make the field even flatter.

[Slawomir]

I would like to conclude this thread with the following confession: in the past years I owned several pieces of astro equipment. I still vividly remember excitement of unpacking and using my first telescope. It was Saxon - a 6" f/8 Newtonian on non-motorised EQ3. Had many many memorable nights of stargazing with it from our balcony in Rockdale in Sydney, and also dipped my feet into astrophotography with this telescope. I had a few more telescopes since, but looking through and using the CFF 105 revived that special astro-thrill I had with my first telescope back in the days.

[Slawomir]

Sorry to resurrect this old thread...

Since I have finished collecting data for my latest image of the Prawn, I decided to fine-tune camera's orthogonality (I have a camera tilting unit from Gerd Neumann).

I think I got it pretty close to perfect, perhaps I could move the camera 0.5-1mm further out, but nonetheless I am now very happy with star shapes: http://cdn.astrobin.com/images/thumbs/503b7ece5ecd9ff60944c83f15fa5727.16 536x16536_q100_watermark_watermark_ opacity-15_watermark_position-6_watermark_size-S_watermark_text-Copyright%20Slawomir%20Lipinski.jpg

I had a chance to use this telescope on about 30 sessions since I've got it. Love the mechanics and optics. Machined tube, machined baffles, FTF 3.2" is rock solid and autofocus is very precise, oil-spaced lens cell seems to cool fast. Refocus is needed perhaps every 1.5-2.0 C change if you are after perfect focus. When changing filters, there is hardly any adjustment needed. I think this scope would be a very nice match for KAF16200 for wide fields, one day perhaps.


Suavi

[gregbradley]

Oh wow, that is spot on. I don't think I have ever seen a plot that good. Nice one.

But the proof is in 1x1 binned exposures and checking each corner for star roundness perfection not really CCD Inspector which can sometimes give 2 results for the same image.

16200 would go well with it. Can it handle a 16803 with its 52mm diagonal? 16200 has a 44mm diagonal from memory. .5 to 1mm is a very large correction by the way.

Greg.

[Slawomir]

Thank you Greg. It took a few iterations to get it right. I won't be adjusting the spacing at this stage, but CCD Inspector consistently indicates that my CFF corrector slightly overcorrects field curvature at the current spacing, so that is why I think I may be a tiny bit off the perfect spacing.

Stars are nicely round though to my eye in the recent test image; it would be silly if I complained about current star shapes :lol:

I would be VERY happy to test either KAF 16200 or KAF 16803, just need to find a donor, or perhaps if things go well, I just wait patiently a few years for a Santa to accumulate sufficient funds :)

[Atmos]

That looks very nice Suavi!! That over correction you mention, that may be what it is designed to do. There is always going to be some level of field curvature.

The 16200 has a diagonal closer to 35mm being an APS-H. A full frame is ~43mm.

[Slawomir]

Thank you clarifying that Colin. I have been assured that this scope is fully corrected to 44mm for imaging with my flattener, and with 3.2inch focuser it should do well with larger chips.