Any Tak users have the TCA-4 Eyepiece Projection Adapter ?

[Omaroo (Chris Malikoff)]

I'm just wanting to know if any Takahashi users have the TCA-4 EP projection adapter. Sounds like a nice unit - where you can encase a 1.25" EP into the unit and then include the unit holding the EP within the optical train - and still be able to adjust its magnification by up to 30% before the T-ring. I like the idea because the focal length of the FS60-C is fairly short (355mm), so being able to use a good quality (Nagler) EP to magnify the image prior to the DSLR would have to be a nice thing to do.

About it:

Consists of three parts for eyepiece projection photography with Takahashi refractors only. The normal 1.25" Takahashi eyepiece holder is unscrewed from the telescope drawtube and replaced by a special compression ring 1.25" eyepiece holder from the TCA-4. A 1.25" eyepiece is inserted into the compression ring (0.965" eyepieces can be used by adding optional 0.965" adapter #TCA9AD) and locked in place by tightening the ring. The TCA-4 body slips over the eyepiece and is in turn locked into place on the compression ring by thumbscrews. An optional T-ring attaches to the telescoping inner tube of TCA-4. The inner tube can be moved in and out of the TCA-4 body to allow the projection distance to be varied from 100mm to 130mm. The projection distance is locked in by thumbscrews on the TCA-4 body. The orientation of the camera can be changed from horizontal to vertical by loosening the thumbscrews at the front of the TCA-4 body, rotating the body to the desired angle, and retightening the thumbscrews. The variable projection distance design allows you to change the magnification to vary the size of the image by 30% without the need to change to a different focal length eyepiece. Needs optional T-ring.

[Dennis]

Hi Chris

Hmm, it looks like I may have the Vixen equivalent – see attached file.

Cheers

Dennis

[Dennis]

The biggest limitation is the tube that houses the eyepiece – this limits the size of eyepiece that you can use, in terms of its outside diameter.

Ironically, my Tak LE 5mm and 7.5mm eyepiece barrels are too large to fit inside the Vixen tube! It holds the Vixen 10mm Plossl nicely.

Cheers

Dennis

[Omaroo (Chris Malikoff)]

Thanks Dennis

How is the image (photographic) quality given a good quality EP? I'd love to fit my 5mm Nagler Type 6, but somehow think that the barrel is going to be way too large by what you're saying. I have a few decent Plossls that might do the trick through.

[Dennis]

Hi Chris

It is difficult to answer that question, as I only ever used the set up for 35mm film photography of Jupiter and the Moon and the results were less than pleasing due to the lack of mirror lock up on my 35mm SLR, the lack of sensitivity of film and only grabbing single exposures – this was in the days before webcam imaging and the stacking 1000’s of frames to “beat” the seeing. I think that Don Parker in the US made use of the eyepiece projection technique to produce some stunning photos of Mars and Jupiter in the days of 35mm film.

I did try the rig out using the Meade LPI a few years ago, and I recollect being satisfied that the limitations were more from the LPI and the seeing conditions rather than the eyepiece + eyepiece projection unit.

All my ToUcam and DMK work has been done using TeleVue x2.5 and x5 PowerMates, so I have not used the Vixen 43mm eyepiece projection adapter for those ccds.

In terms of ease of set up, I find it is much easier to use a Barlow (a single component) rather than inserting an eyepiece into the adapter tube, assembling the body and then attaching the camera and unit to the ‘scope. A minor point, but certainly worth noting as there are a lot of screws to fiddle with, to hold the eyepiece and rotate the assembly to the optimum position.

I guess that if you can pick up a unit at reasonable cost (hah – yeah, Tak gear!) it might be worth experimenting just to see what results you can obtain using the variable projection capability of the unit, but my main recommendation would be to use PowerMates if the Barlow configuration is feasible with your set up.

I think that the current thinking tends to favour Barlows for hi-res Lunar and Planetary work, and so far that has proven so successful for me, I have not been inclined to even experiment with the Vixen Unit.

Cheers

Dennis

[Omaroo (Chris Malikoff)]

Thanks for the considered answer Dennis - I appreciate it

I guess that, being only 355mm in focal length, I'm not going to use the Tak for planetary - except for the moon maybe. I was wanting to get a narrower FOV than that which I get with the DSLR alone attached to the f/6 flattener - primarily for objects such as B33 and M42, 47Tuc, Eta C and Omege C. I think that this system would be ideal. Being variable, and then being able to choose from a plethora of EP's, I reckon that the range of magnifications you'd get would be almost infinite - within the practical scope of the optics.

I hate to admit it, but I've never known or even investigated whether you can attach a DSLR camera T-ring/adapter to a 1.25" barlow system. Can you?

[Dennis]

Technically it appears feasible, although I haven’t tried it. The TeleVue 1 ¼” PowerMates have the capability to attach a T Ring – see attached screen-print from BinTel website.

I find that with any system outside of the ubiquitous Meade and Celestron 3rd party accessory market, it is often quite difficult to determine if a photographic configuration will work, or not, until after one has made the purchase!

Cheers

Dennis

[gbeal]

Like Den The Man, I too assumed the eyepiece would have to be a "certain" size, to fit internally.
I have and use occasionally, a similar sort of eyepiece projection unit for the Zeiss, and the Zeiss orthos fit inside, just. You would want to ensure that the adaptor actually fitted the eyepieces you have, or intend, and I seriously doubt the Naglers would fit.
Same place for this accessory as where the scope came from?

[Omaroo (Chris Malikoff)]

Originally Posted by gbeal

Same place for this accessory as where the scope came from?

Yes Gary