My CFF 105 mm f/6 oil spaced triplet has arrived
Posted 18 September 2013 - 11:00 AM
I won't say "finally" arrived, as the waiting time was was quite short compared to what is the norm for some (the) other oil spaced "artisan-telescopes" (AP and TEC) out there.
By "artisan telescope" I mean a small(ish) manufacturer who designs and grinds their optics.
From the initial discussions about the possibility of a new run of the 102 mm f/6.3 or alternatively introducing a completely new 105 mm f/6, the whole process took about 6 months. Including the designwork of the optics and mechanical parts.
I'm pretty sure many people here have never heard of CFF Telescopes (and by which right I mention CFF in the same sentence as AP and TEC ).
CFF was equally unknown to me, until I started a thread about oil spacing longevity here on this forum last year. Link to that thread here.
Catalin Fus, part owner and mechanical designer at CFF Telescopes, posted a reply which I thought indicated he knew what he was talking about, so naturally I checked out what CFF Telescopes was.
For some time I had been tempted to buy a high quality fast refractor in the 4" class, as a smaller and lighter alternative to my AP 130 EDFGT, which I've frankly found (for mobile observing) relatively demanding lugging- and mounting-wise. I Inquired about the 102 mm f/6.3, but found that the run was sold out. Catalin promised to keep me updated about a possible new run, and when other potential customers showed an interest, Catalin asked us if we would prefer a new run of the 102 mm f/6.3 or a new design in the form of a 105 mm f/6 using FPL53 glass. The 105 mm was universally preferred, and Catalin took my order in February.
So why the CFF 105 mm f/6 and not one of the competitors?
Three main things, really:
Firstly, my personal preference for oil spacing. I like the thermal properties of my AP, and oil spacing seems (to me) like a "safe" design as far as longevity and possible collimation issues are concerned.
Secondly,I liked CFF’s positive attitude and very clear ambition. Everything about CFF (and GPU) I found on the internet was positive, and all our communication gave me a very good impression of the company (as personified by Catalin).
Thirdly, compared to a TEC 110 FL but also to all LZOS-lensed telescopes in the 4” class (APM and Officina Stellare), the price was quite competitive.
According to the CFF website (link here), CFF is a collaboration between Catalin Fus (mechanical design and mecdhanical assembly) and Pal Gyulai (lens designer and optician at CFF, owner of GPU Optical).
Pal is the optician behind GPU, which (while relatively unknown) has a very high reputation for quality optics. I've not been able to find one negative comment on the Internet about either GPU or CFF, so I decided to trust them. There are some old reviews here on CN of older GPU scopes, and they are quite positive, even if no direct side-by-side comparisons with other similar size telescopes were made.
The 105 mm f/6 is a FPL53-based oil spaced triplet.
Being oil spaced, one surface needs to be aspherized, which apparently requires hand figuring.
CFF guarantees a Strehl ratio of 0.96, but claims that the “typical” Stehl of delivered telescopes is around 0.98.
I ordered mine with a 3" Feathertouch 3035 focuser.
White tube colour.
Case with space for OTA with rings and dovetail(s) (no space for additional accessories in the case).
“Standard” 180 mm back-focus distance.
All those are things that Catalin apparently will ask your wishes for, so a significant amount of customization of the package seems to be possible.
After receiving the telescope, what first struck me when opening the parcel was how well it was packaged. Double boxed with styrofoam sheet in between. Then the telescope case, and the OTA further stuffed securely in place by styrofoam "peanuts".
The next thing was the case, which is high quality and rugged. More rugged than the case for my AP, I'd say. Something you can put in the trunk of your car and pack other stuff on top off, which I’d be a bit hesitant to do with the AP case, not because it’s not strong enough, but because the external finish might suffer.
The telescope itself is beautifully made (pictures a bit more professional looking than mine, can be found on the CFF website here. The white OTA (serial #2) shown on the right in the pictures on the website is mine.
The white paint is even and nicely tectured, so that it won't be too slippely when covered with dew.
The black parts (except the Feathertough focuser) are painted, not anodized as on some other scopes such as the AP.
I believe the painting is really powdercoating, so the surface should be very durable.
The finish and mechanical workmanship is absolutely first class.
Next to the AP, I honestly think that the CFF is similarly beautifully made and finished. except perhaps in such "engineering excess" (which I appreciate and admire) as the AP having a machined/turned main tube while the CFF is made in a more "normal" fashion.
Aesthetically, I think a somewhat slimmer dewshield (which has a nicely working click-lock mechanism for locking it in the extended position) might look a tiny bit more "balanced" (compared to the AP, which looks a bit more "trim" in that regard, but that is just a matter of visual tase, I suppose.
Given that the CFF lens cell has push-pull screws for colimation, I can understand why it needs to be “fatter” than the AP lens cell.
However, since the rings and dovetail are what dictate the case width/height, it would not have an impact on tranport size anyway.
I've only had the scope out twice so far, so I don't have much experience with optics yet except that I saw no indication of anything other than very high optical quality. Which is precicely what I expected, given Pal's reputation.
On the second night, I was able to use a 5.2 mm Pentax XL with AP Barcon (a magnification of about 240) with no apparent image beakdown. Ridiculously small exit pupil for me, as I have a number of disturbing floaters. This, of course being the area where “only” 105 mm of aperture shows its limitations. But that is the price of compact size...
I could not detect any colour on the moon limb, and the view was very sharp.
A start test showed no faults that I could detect, given the (decent, but not perfect) seeing.
Here is what Pal wrote about the optics on the CFF Yahoo group link to web page (note to CN moderators: I hope a direct quote is OK, as Yahoo is an open forum?):
“...the optical performance of the new 105mm lens type really made me happy even in the autocollimator. This is an extremely sensitive test, as the light passes the lens twice. For this reason, every optical problem (including false color, which could easily be a problem at F/6 focal ratio) is doubled when a lens is checked in auto-collimation. Additionally, the seeing and transparency is always absolutely perfect in the autocollimator (as it is in a room with serious thermal insulation and the air can be filtered) so, even these small problems that would be easily washed out by seeing problems during an under-the-starry-sky test, they are easily visible in the autocollimator. In practice, even lenses that give only mediocre results in the autocollimation test, perform actually rather well under the starry sky (in the past years, I had the chance to see a really wide spectrum of optical quality levels while repairing/adjusting lenses from some other manufacturers). Now I have to tell you, that these 105mm lenses performed practically perfectly even in this really demanding test, the only "problem" I could detect was the natural spherochromatism, but it is under excellent control, especially taking into account the extremely fast focal ratio. Thanks to the excellent performance of the FPL53 glass (and the ideal mating glasses used, that match the partial dispersions of the FPL53 practically perfectly) I could not detect any focal length differences at different colors, even violet color is under excellent control. So, I think we can conclude that it was a good decision to develop this new lens type! This is nice to know after the amount of money and efforts invested! So, I can only hope that our customers will be similarly happy while using them as we were after testing them! :-)”
With a single eyepiece, the telescope seems to balance roughly in the middle of the tube section visible when the dewshield is retracted, meaning where the rings and dovetail would be when stowed for transport/storage. One notable thing is perhaps that the dovetail needs to be pretty short, maximum about 150 mm (6"), unless riser blocks are used, which might make the dovetail/rings hard to fit into the case.
All in all I'm highly impressed. Both by the telescope itself, and by the whole process from initial contact with Catalin, and all communication we've had along the way.
Time will tell is this telescope turns out to be "Goldilocks" when it comes to ease of transport, mounting, use, and most importantly the views it will provide, but so far it looks very promising.
Pictures to follow in the next posts, even if none of my pictures are as nice as those on CFF's homepage...
Posted 18 September 2013 - 11:06 AM
Posted 18 September 2013 - 11:09 AM
Note that the perspective makes the CFF seem larger than it would have appeared if I'd been smart enough to take the photo from above.
That said, the AP really is very slim for it's aperture...
Posted 18 September 2013 - 11:11 AM
Posted 18 September 2013 - 12:00 PM
Posted 18 September 2013 - 04:27 PM
Interesting choice, sounds very nice.
Posted 18 September 2013 - 05:05 PM
Posted 18 September 2013 - 05:13 PM
Posted 18 September 2013 - 06:32 PM
Looks like a top end scope, it is frighteningly expensive in USD.
so it's around $3500? Pricey but $1,000 less than the TEC for only 5mm less lens. Good to see more alternatives out there.
Posted 18 September 2013 - 06:36 PM
Posted 18 September 2013 - 06:53 PM
Posted 18 September 2013 - 10:58 PM
Thank you for the kind comments.
This will be very short, as I must rush to work (early morning here in my time-zone)...
About the price:
In Europe all prices must be given including the sales tax (23 % in this case). So the tax free export price (which is what should be used to compare the cost to a scope sold on your side of the Atlantic) would be ca $ 3500 for the Feathertouch-equipped model, just like Scott calculated.
Posted 19 September 2013 - 03:55 AM
Posted 19 September 2013 - 03:59 AM
Very nice report and informative photos.
Now it will be hard time for me to wait on my CFF, which I ordered a week ago...
Posted 19 September 2013 - 03:03 PM
It's certainly a beauty!
I have seen some of Catalin's work and I might have to look into a 140 for myself.
Posted 21 September 2013 - 12:53 AM
Onhan se hieno kiikari (kaukoputki) !!!
Interesting choice, sounds very nice.
Kiitos. Vaikuttaa oikein lupaavalta valinnalta...
Thank you. It seems to be a promising choice.
Posted 21 September 2013 - 12:58 AM
How heavy is the OTA with rings included, Patrick?
I don't have suitable scales to check, but the manual and CFF-website claims 5.9 kg with rings.
If the specified weight of a TEC 110 is correct (4.5 kg), it really is an impressive feat. Does the TEC lens cell have collimation provision?
Posted 21 September 2013 - 01:05 AM
That does make it a pretty good value. Is it a hassle to import it?
Well, being in Europe, I have no experience of importing stuff into the USA, but I don't see why it would be a problem. Works well enough the other way around...
I do know several people here on CN have imported Berlebach tripods from Europe, so I guess someone must also have ordered optics from Europe?